WO2012017613A1 - Surface light-source apparatus and liquid crystal display apparatus - Google Patents

Surface light-source apparatus and liquid crystal display apparatus Download PDF

Info

Publication number
WO2012017613A1
WO2012017613A1 PCT/JP2011/004150 JP2011004150W WO2012017613A1 WO 2012017613 A1 WO2012017613 A1 WO 2012017613A1 JP 2011004150 W JP2011004150 W JP 2011004150W WO 2012017613 A1 WO2012017613 A1 WO 2012017613A1
Authority
WO
WIPO (PCT)
Prior art keywords
light
guide plate
light source
light guide
illumination
Prior art date
Application number
PCT/JP2011/004150
Other languages
French (fr)
Japanese (ja)
Inventor
令奈 西谷
染谷　潤
栄二 新倉
小島　邦子
Original Assignee
三菱電機株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 三菱電機株式会社 filed Critical 三菱電機株式会社
Priority to JP2012527577A priority Critical patent/JPWO2012017613A1/en
Priority to TW100127168A priority patent/TW201222098A/en
Publication of WO2012017613A1 publication Critical patent/WO2012017613A1/en

Links

Images

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0033—Means for improving the coupling-out of light from the light guide
    • G02B6/0035—Means for improving the coupling-out of light from the light guide provided on the surface of the light guide or in the bulk of it
    • G02B6/0036—2-D arrangement of prisms, protrusions, indentations or roughened surfaces
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0033—Means for improving the coupling-out of light from the light guide
    • G02B6/005—Means for improving the coupling-out of light from the light guide provided by one optical element, or plurality thereof, placed on the light output side of the light guide
    • G02B6/0055—Reflecting element, sheet or layer
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0033—Means for improving the coupling-out of light from the light guide
    • G02B6/0058—Means for improving the coupling-out of light from the light guide varying in density, size, shape or depth along the light guide
    • G02B6/0061—Means for improving the coupling-out of light from the light guide varying in density, size, shape or depth along the light guide to provide homogeneous light output intensity
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0075—Arrangements of multiple light guides
    • G02B6/0076—Stacked arrangements of multiple light guides of the same or different cross-sectional area

Definitions

  • the present invention relates to a surface light source device that converts a plurality of light beams emitted from a plurality of light sources into planar illumination light, and a liquid crystal display device that includes the surface light source device as a backlight unit.
  • the liquid crystal display element included in the liquid crystal display device does not emit light by itself, it is necessary to provide a backlight device on the back of the liquid crystal display element as a light source (surface light source device) for illuminating the liquid crystal display device.
  • a cold cathode fluorescent lamp hereinafter referred to as CCFL (Cold Cathode Fluorescent)
  • CCFL Cold Cathode Fluorescent
  • LEDs Light Emitting Diodes
  • an LED In an element generally called an LED, a monochromatic LED that obtains monochromatic light such as red, green, or blue by direct light emission of the LED, or a yellow phosphor provided in the package by monochromatic blue light by direct light emission of the LED is excited.
  • white LEDs that obtain white light.
  • the light emitted from the direct light emitting LED has high monochromaticity and high color purity.
  • the color reproduction area can be expanded and a liquid crystal display providing a vivid image An apparatus can be provided.
  • White LEDs have high luminous efficiency, and low power consumption can be expected by adopting them as light sources for backlight devices.
  • the brightness of the LED can be controlled in the range of 0% to 100% by current control, the power consumption is greatly reduced by changing the light quantity of the LED according to the brightness of the image, In addition, the contrast of dynamic images can be improved.
  • the backlight device includes a plurality of conventional light sources arranged on the back surface of a liquid crystal display element to generate a planar light source.
  • the light source is placed near the edge of the light guide plate, and using this light guide plate, linear light emitted from multiple light sources is converted into planar light, so-called side light method or edge light method is widely adopted Has been.
  • an LED that has a large light emission output per unit light emitting area and can reduce the number of light sources with respect to necessary luminance is adopted. It is effective.
  • Such a problem can be improved, for example, by adopting a configuration in which a large number of point light sources are arranged in a line at a narrow interval so as to be close to a linear light source. Since the backlight device of the liquid crystal display device that requires distribution requires a large number of point light sources, there are problems in terms of power consumption, ease of assembly, and cost.
  • Patent Document 1 a through hole parallel to the light incident surface of the light guide plate is formed in the light guide plate.
  • a light diffusing structure that effectively diffuses incident light is realized by this through hole.
  • This light diffusion structure diffuses the light emitted from each of the point light sources in the arrangement direction of the point light sources.
  • the light emitted from the point light source enters the light guide plate from the side surface of the light guide plate, refracts, and is guided to the surface of the light guide plate.
  • the present invention has been made in view of the above problems, and an object thereof is to provide a surface light source device and a liquid crystal display device in which unevenness of in-plane luminance distribution is suppressed with a simple and small configuration.
  • a surface light source device includes a plurality of first light sources that respectively emit a plurality of first light beams, a light incident end surface on which the plurality of first light beams are incident, and a plurality of first light sources.
  • a first light guide plate having a front surface on which one optical element is formed, and a reflective member disposed to face the back surface of the first light guide plate, wherein the plurality of first optical elements are:
  • the plurality of first light beams incident on the light incident end surface are internally reflected in the direction of the reflecting member to generate planar light, and the reflecting member is emitted from the back surface of the first light guide plate.
  • the planar light is reflected in the direction of the first light guide plate, and the first light guide plate transmits the planar light incident from the reflection member and emits the first illumination light from the front surface. Is.
  • a liquid crystal display device includes a surface light source device according to the first aspect and a liquid crystal that generates image light by spatially modulating the intensity of the planar light emitted from the surface light source device.
  • a display element includes a liquid crystal that generates image light by spatially modulating the intensity of the planar light emitted from the surface light source device.
  • a surface light source device and a liquid crystal display device that have a small configuration and suppress uneven luminance distribution due to directivity of light emitted from the first light source.
  • FIG. 1 shows typically the structure of the liquid crystal display device of Embodiment 1 which concerns on this invention. It is the schematic of the planar light source of the liquid crystal display device of Embodiment 1 which concerns on this invention.
  • 2 is a schematic cross-sectional view of a micro optical element formed on the front surface of the light guide plate of Embodiment 1.
  • FIG. 3 is a perspective view schematically showing an example of the structure of the optical sheet of Embodiment 1.
  • FIG. It is a figure which shows typically the structure of the liquid crystal display device of Embodiment 2 which concerns on this invention. It is the schematic of the planar light source of the liquid crystal display device of Embodiment 2 which concerns on this invention.
  • FIG. 6 is a diagram illustrating a schematic configuration of a planar light source of a liquid crystal display device according to Embodiment 3.
  • FIG. It is a figure which shows schematic structure of the other planar light source of the liquid crystal display device of Embodiment 3.
  • FIG. It is a figure which shows schematic structure of the other planar light source of the liquid crystal display device of Embodiment 3.
  • FIG. It is a conceptual diagram explaining that the light ray radiate
  • FIG. 1 is a configuration diagram schematically showing a configuration of a liquid crystal display device 101 which is a transmissive display device according to the first embodiment of the present invention.
  • FIG. 2 is a diagram schematically showing a planar light source 200 constituting the backlight unit 5 ⁇ / b> A of the liquid crystal display device 101.
  • the short side direction of the liquid crystal optical element 10 is defined as the Y-axis direction
  • the long side direction is defined as the X-axis direction
  • the direction perpendicular to the XY plane (display surface) is defined as the Z-axis direction.
  • the direction on the display surface 10f side of the liquid crystal display element 10 is the + Z-axis direction, and the opposite direction is the ⁇ Z-axis direction. Further, the upward direction of the liquid crystal display device 101 is defined as the + Y axis direction, and the opposite direction is defined as the ⁇ Y axis direction. The right direction toward the display surface 10f of the liquid crystal display device 101 is the + X axis direction, and the left direction is the ⁇ X axis direction.
  • a liquid crystal display device 101 includes a transmissive liquid crystal display element 10, an optical sheet 11 that is a first optical sheet, an optical sheet 12 that is a second optical sheet, and a surface light source device.
  • the constituent elements 10, 11, 12, 5A are stacked and arranged in the Z-axis direction.
  • the liquid crystal display element 10 has a display surface 10f parallel to an XY plane including an X axis and a Y axis perpendicular to the Z axis. Note that the X axis and the Y axis are orthogonal to each other.
  • the liquid crystal display device 101 further includes a liquid crystal display element driving unit (not shown) that drives the liquid crystal display element 10 and a light source driving unit (not shown) that drives the light source groups 20Ga and 20Gb included in the backlight unit 5A. .
  • the operations of the liquid crystal display element driving unit and the light source driving unit are controlled by a control unit (not shown).
  • the control unit performs image processing on a video signal supplied from a signal source (not shown) to generate a control signal, and supplies the control signal to the liquid crystal display element driving unit and the light source driving unit.
  • the light source driving unit drives the light source groups 20Ga and 20Gb according to a control signal from the control unit to emit light from the light source groups 20Ga and 20Gb.
  • the light source group 20Ga includes a plurality of light sources 20,..., 20 arranged in a line along the Y-axis direction as shown in FIG. 2, and the light source group 20Gb is also arranged in a line along the Y-axis direction. It consists of a plurality of light sources 20,.
  • the backlight unit 5A is composed of light source groups 20Ga and 20Gb, a light guide plate 21, and a light diffusion reflection sheet 26.
  • the light source groups 20Ga and 20Gb are arranged to face the light incident end faces 21ea and 21eb provided on both end faces in the X-axis direction of the light guide plate 21, respectively.
  • the light beams ILa and ILb emitted from the light source groups 20Ga and 20Gb are incident toward the central direction from the light incident end surfaces 21ea and 21eb on the both end surfaces of the light guide plate 21.
  • the light diffusion reflection sheet 26 is disposed so as to face the surface 21 b (surface on the ⁇ Z axis direction side) opposite to the liquid crystal display element 10 of the light guide plate 21 and to be parallel to the light guide plate 21.
  • the light source groups 20Ga and 20Gb have a configuration in which light sources 20,..., 20 such as a plurality of LEDs that emit white light are arranged in the Y-axis direction at regular intervals.
  • the light guide plate 21 is arranged in parallel to the display surface 10f of the liquid crystal display element 10, and has fine optical elements 21d, ..., 21d on the surface of the light guide plate 21 on the liquid crystal display element 10 side.
  • Light diffusion refers to a phenomenon in which light traveling on a medium strikes molecules in the medium, causing a shift in the traveling direction, and traveling in a wider range than the original traveling direction or specular reflection direction. .
  • the phenomenon spreading by its own divergence angle is also called light diffusion.
  • the light guide plate 21 emits white light beams ILa and ILb emitted from the light source groups 20Ga and 20Gb to the ⁇ Z axis direction by the refractive action of the micro optical elements 21d,..., 21d formed on the surface of the light guide plate 21 in the + Z axis direction. Are converted into planar illumination lights BLa and BLb.
  • the illumination lights BLa and BLb are emitted from the light guide plate 21 as the first planar light toward the light diffusion reflection sheet 26 disposed on the ⁇ Z axis direction side of the light guide plate 21.
  • the fine optical elements 21d,..., 21d are optical elements that generate illumination lights BLa and BLb by converting the traveling directions of the light beams ILa and ILb into the ⁇ Z-axis direction by refraction.
  • the illumination lights BLa and BLb emitted toward the light diffusive reflection sheet 26 are diffused by the light diffusive reflection sheet 26 and reflected toward the + Z-axis direction.
  • the light diffusing and reflecting sheet 26 for example, a light diffusing and reflecting sheet based on a resin such as polyethylene terephthalate or a light diffusing and reflecting sheet obtained by depositing metal on the surface of a substrate having a fine uneven shape is used. Can do.
  • White illumination light passes through the light guide plate 21, the optical sheet 12, and the optical sheet 11, and is emitted from the backlight unit 5A toward the back surface 10b of the liquid crystal display element 10.
  • the optical sheet 11 has an action of directing the traveling direction of the illumination lights BLa and BLb emitted from the backlight unit 5A in the normal direction to the screen of the liquid crystal display device 101.
  • the optical sheet 12 suppresses optical influences such as fine illumination unevenness.
  • the liquid crystal display element 10 has a liquid crystal layer (not shown) parallel to the XY plane orthogonal to the Z-axis direction.
  • the display surface 10f of the liquid crystal display element 10 has a rectangular shape, and the X-axis direction and the Y-axis direction shown in FIG. 1 are directions along two mutually orthogonal sides of the display surface 10f.
  • the liquid crystal display element driving unit can change the light transmittance of the liquid crystal layer in units of pixels or sub-pixels according to a control signal supplied from the control unit.
  • Each pixel is further composed of three or four sub-pixels, and each of the sub-pixels is either red, green or blue light only, or any of these colors, for example, four colors including yellow.
  • a color image can be generated by controlling the transmittance of each sub-pixel.
  • the liquid crystal display element 10 can generate image light by spatially modulating the intensity of the illumination lights BLa and BLb incident from the backlight unit 5A, and can emit the image light from the display surface 10f.
  • the light guide plate 21 is a plate-like member formed of a transparent member, for example, having a thickness of 4 mm.
  • microscopic optical elements 21 d,..., 21 d having a hemispherical convex shape (hereinafter referred to as a convex lens shape) are formed on the surface (front surface) of the light guide plate 21 on the liquid crystal display element 10 side. Is formed.
  • the fine optical elements 21d,..., 21d emit light rays ILa and ILb propagating in the light guide plate 21 from the back surface 21b on the opposite side to the liquid crystal display element 10 in the ⁇ Z-axis direction. The light is converted into BLa and BLb.
  • the light beams ILa and ILb incident from the light incident end faces 21ea and 21eb of the light guide plate 21 travel in the X-axis direction while being repeatedly reflected in the light guide plate 21 by total reflection at the interface between the light guide plate 21 and the air layer.
  • the light beams ILa and ILb there are light beams that do not satisfy the total reflection condition at the interface between the back surface 21b of the light guide plate 21 and the air layer.
  • the light beam is emitted from the back surface 21 b of the light guide plate 21 toward the light diffusion reflection sheet 26.
  • the fine optical elements 21d,..., 21d provided on the surface of the light guide plate 21 are formed in the XY plane, and the arrangement density (that is, the number per unit area and the size thereof) of the fine optical elements 21d,. Etc.) vary spatially.
  • the in-plane luminance distribution of the illumination lights BLa and BLb emitted from the light guide plate 21 can be controlled.
  • FIG. 2 as the light beams ILa and ILb travel in the traveling direction (X-axis direction in FIG. 2) from the light incident end faces 21 ea and 21 eb of the light guide plate 21 toward the center of the light guide plate 21.
  • the in-plane luminance distribution is a distribution indicating the level of luminance with respect to a position expressed in two dimensions on an arbitrary plane.
  • the in-plane luminance distribution of the backlight unit 5A is the illumination light related to the position on the surface of the light guide plate 21 (surface facing the liquid crystal display element 10) expressed in two dimensions (XY plane). This is a distribution indicating the level of brightness of BLa and BLb.
  • the illumination lights BLa and BLb are emitted from the surface of the light guide plate 21 to illuminate the back surface 10b of the liquid crystal display element 10.
  • the arrangement density of the micro optical elements 21d,..., 21d is continuously from sparse to dense from the vicinity of the light incident end faces 21ea and 21eb in the light guide plate 21 toward the vicinity of the center position in the X-axis direction. Take a changing configuration.
  • the shape of the micro optical element 21d for example, as shown in FIG. 3, a convex lens shape having a curvature of about 0.15 mm and a maximum height Hmax of about 0.005 mm can be adopted.
  • the refractive index of the micro optical element 21d may be about 1.49.
  • the material of the light guide plate 21 and the fine optical element 21d can be acrylic resin, but is not limited to this material. As long as the material has good light transmittance and excellent moldability, other resin materials such as polycarbonate resin or glass material may be used instead of acrylic resin.
  • the fine optical element 21d has a convex lens shape, but the present invention is not limited to this.
  • Other shapes may be adopted as long as the LED light that travels in the light guide plate 21 in the X-axis direction is refracted in the Z-axis direction and emitted toward the light diffusion reflection sheet 26.
  • the convex lens shape has an advantage that it can be refracted with a transparent structure and is easy to manufacture because it is a simpler shape than the structure of a prism or the like. Further, even when the light guide plate 21 is enlarged, it can be manufactured by printing, so that it is possible to easily cope with the enlargement of the light guide plate 21.
  • the laser beam can be refracted in the Z-axis direction even with a random uneven shape such as sandblasting.
  • the convex shape can be easily designed, and thus a surface that achieves a uniform luminance distribution. There is an advantage that the design of the light source 200 is easy.
  • the light source group 20Ga, 20Gb includes light sources 20,..., 20 such as LEDs that emit white light having a very wide wavelength band from 420 nm to 700 nm.
  • the color filter of the liquid crystal display element 10 cuts out the light of three colors of red, green and blue, and adjusts the color mixture ratio of the three colors of light. Display is performed. For example, when four color filters in which yellow is added to red, green, and blue, light of four colors can be cut out, and color can be adjusted by adjusting the color mixture ratio of the four colors of light. Display is performed.
  • the light emitted from the light source groups 20Ga and 20Gb has directivity, and is an angle of a substantially Lambertian distribution with the full width at half maximum being 120 degrees centered on the normal direction of the light emitting surface of the light source groups 20Ga and 20Gb.
  • the Lambert distribution is a distribution in which the intensity at the angle center is maximized and the intensity decreases with a cosine function as the angle increases.
  • the light beams ILa and ILb respectively emitted from the light source groups 20Ga and 20Gb travel in the X-axis direction while being totally reflected by the inner surface of the light guide plate 21.
  • the light totally reflected from the inner surface by the fine optical element 21d provided on the surface of the light guide plate 21 becomes illumination lights BLa and BLb.
  • the illumination lights BLa and BLb are emitted in the ⁇ Z-axis direction from the back surface 21b of the light guide plate 21 toward the light diffusion reflection sheet 26.
  • the illumination lights BLa and BLb are diffused and reflected by the light diffusion reflection sheet 26 to become illumination lights BLa and BLb directed in the + Z-axis direction, pass through the light guide plate 21 and exit from the surface of the light guide plate 21.
  • the illumination lights BLa and BLb traveling in the + Z-axis direction are emitted from the surface of the light guide plate 21, they are further diffused by the refractive action of the micro optical element 21d.
  • the light beams ILa and ILb emitted from the light source groups 20Ga and 20Gb propagate an optical distance corresponding to at least twice the thickness of the light guide plate 21 before being emitted from the surface of the light guide plate 21. Therefore, before the light beams ILa and ILb are emitted from the surface of the light guide plate 21, it is possible to ensure an optical distance for diffusing with the divergence angle of the light guide plate 21 while suppressing the size of the backlight unit 5A.
  • the light beams ILa and ILb are converted into illumination lights BLa and BLb which are planar lights by the optical action of the micro optical element 21d.
  • the illumination lights BLa and BLb are diffused and reflected by the light diffusion reflection sheet 26 in the optical path from the surface of the light guide plate 21 until it is emitted. Due to this light diffusion action, the illumination lights BLa and BLb are diffused in the XY plane, and are emitted from the surface of the light guide plate 21 after being spatially overlapped in the arrangement direction (Y-axis direction) of the light sources 20.
  • the illumination lights BLa and BLb are emitted from the surface of the light guide plate 21, they are further diffused by the refractive action of the micro optical elements 21d,. Due to these light diffusion actions, the in-plane luminance distribution of the illumination lights BLa and BLb emitted from the backlight unit 5A is uniform in the arrangement direction (Y-axis direction) of the light sources 20,..., 20 constituting the light source groups 20Ga, 20Gb. It becomes. For the same reason, it is possible to obtain excellent uniformity in luminance distribution at positions other than the vicinity of the light incident end of the light guide plate 21.
  • the structure for obtaining the light diffusing action is provided along the normal direction of the image display surface 10f, that is, the direction perpendicular to the surface of the display surface 10f. Further, an optical path for efficiently diffusing light in the thickness direction of the backlight unit 5A is efficiently provided by using the thickness of the light guide plate 21 and the light reflection optical path. For this reason, the backlight unit 5A does not increase in size in the in-plane direction of the display surface 10f of the liquid crystal display element 10 (in-plane direction of the XY plane), and the width of the bezel that is the cabinet portion surrounding the image display portion is increased. A thin design is possible, and it is possible to suppress uneven brightness distribution of the illumination lights BLa and BLb emitted from the backlight unit 5A.
  • the backlight unit 5A generates illumination lights BLa and BLb having a uniform luminance distribution in the X-axis direction by the optical action of the micro optical elements 21d,. For this reason, the backlight unit 5A can suppress luminance distribution unevenness in both the Y-axis direction, which is the arrangement direction of the light sources 20, ..., 20 and the X-axis direction perpendicular to the Y-axis direction. That is, it is not necessary to provide two types of optical elements, and the number of optical coupling portions between the optical elements can be reduced. As a result, the loss of light at the coupling portion between the optical elements is suppressed, the light use efficiency is improved, and the number of parts is reduced and the assemblability is improved.
  • the surface light source device is configured by one backlight unit 5A.
  • the light intensity of the light beams ILa and ILb propagating in the light guide plate 21, that is, the light power density is guided.
  • the uniformity of the luminance distribution is realized by changing the arrangement density of the micro optical elements 21d, ..., 21d provided on the surface of the optical plate 21.
  • the arrangement density of the micro optical elements 21d, ..., 21d is sparse, and the vicinity of the center position in the X-axis direction where the light power density is small.
  • the arrangement density of the micro optical elements 21d,..., 21d continuously changes from sparse to dense along the X-axis direction so that the arrangement density of the micro optical elements 21d,.
  • the luminance distribution in the X-axis direction of the illumination lights BLa and BLb emitted from the back surface 21b of the light guide plate 21 becomes uniform.
  • Such illumination lights BLa and BLb are diffused and reflected by the light diffusion reflection sheet 26 and travel toward the liquid crystal display element 10. Therefore, the illumination lights BLa and BLb that are reflected by the light diffusion reflection sheet 26 and then pass through the light guide plate 21 and are emitted from the backlight unit 5A toward the liquid crystal display element 10 have uniform luminance even in the X-axis direction. Have a distribution.
  • FIG. 4 is a perspective view schematically showing an example of the optical structure of the optical sheet 11.
  • the surface of the optical sheet 11 has a structure in which a plurality of convex portions 11p,..., 11p are regularly arranged in the X-axis direction along a plane parallel to the display surface 10f. ing.
  • Each convex part 11p has a triangular prism shape in cross section, the apex angle part of the convex part 11p protrudes toward the liquid crystal display element 10, and the ridge line forming the apex part extends in the Y-axis direction.
  • the interval between the adjacent convex portions 11p, 11p is constant.
  • the liquid crystal display device 101 reduces the light beams ILa and ILb emitted from the light source groups 20Ga and 20Gb in which the plurality of point light sources 20,. It can be converted into uniform illumination lights BLa and BLb by a simple light diffusion structure in terms of the number of points.
  • the light diffusion structure is provided along the normal direction (Z-axis direction) of the image display plane (XY plane) of the liquid crystal display device 101, It is not necessary to arrange the light diffusion structure so as to be adjacent in the Y-axis direction. Thereby, the ratio of the area of the backlight unit 5A to the area of the image display plane can be reduced. That is, it is possible to realize the liquid crystal display device 101 in which the width of the bezel that is the cabinet portion surrounding the image display portion is narrowed while providing an image with good image quality. Further, since the light propagation part is designed with the thickness of the light guide plate 21, the liquid crystal display device 101 can be thinned.
  • the liquid crystal display device 101 capable of displaying a clear image can be provided.
  • the luminance distribution unevenness can be suppressed by reducing the number of light sources as compared with the prior art, and the effect of reducing power consumption by reducing the number of light sources can also be obtained.
  • the light source 20,..., 20 such as a plurality of LEDs that emit white light having a very wide wavelength band from 420 nm to 700 nm is one-dimensionally arranged in the light source of the backlight unit 5A.
  • the light source groups 20Ga and 20Gb are employed, the present invention is not limited to this.
  • a light source group is used in which three types of LED light sources each emitting single-color light of red, green, and blue are periodically arranged in a one-dimensional direction so that the distance between the LED light sources of the same color is constant. Also good.
  • a light source group in which four-color LED light sources, for example, a yellow LED light source is added to the above three types of LED light sources in a one-dimensional direction is employed. May be.
  • the backlight unit 5A of the liquid crystal display device 101 of the present embodiment it is possible to efficiently uniformize the light from the plurality of light sources 20,. Therefore, it is possible to suppress luminance distribution unevenness and color unevenness.
  • the liquid crystal display element 10 of the liquid crystal display device 101 includes a color filter therein, and transmits only light of a part of the wavelength of white light emitted from the backlight unit 5A by the color filter. For example, when displaying in three colors, color expression is performed by extracting display colors of red, green, and blue.
  • the liquid crystal display device 101 can achieve both high light utilization efficiency and a wide color reproduction range.
  • LEDs are employed as the light sources 20 of the light source groups 20Ga and 20Gb of the backlight unit 5A
  • the present invention is not limited to this.
  • a high effect can be obtained by applying a light source unit in which a plurality of light sources emitting light having a small light emitting area and high directivity, such as LEDs, are arranged at intervals, as a side light type light source.
  • the luminance distribution is uniform by optimizing the divergence angle of the emitted light of the laser light source, the arrangement interval of the laser light sources, and the thickness of the light guide plate 21 The effect of making can be obtained.
  • the laser light source has higher monochromaticity than LED and can emit a high-purity color
  • adopting the laser light source as the light source 20,..., 20 for the backlight unit 5A provides a color reproduction range.
  • An extremely wide liquid crystal display device can be provided.
  • the light output with respect to the light emitting area can be increased, the number of light sources can be reduced, which is effective when the sidelight type or edge light type backlight unit 5A is used in a large screen display device. It is.
  • the light guide plate 21 receives the light beams ILa and ILb that are incident from the light incident end faces 21ea and 21eb and propagate through the light guide plate 21, and propagate in the ⁇ Z-axis direction by reflection or refraction. It has an optical action to convert to BLb. Further, since the light guide plate 21 provided in the backlight unit 5A and the micro optical elements 21d,..., 21d provided on the light guide plate 21 are all made of a transparent member, the light guide plate 21 is composed of the light diffusion reflection sheet 26. From the illumination light BLa and BLb reflected in the + Z-axis direction. Thus, by forming the light guide plate 21 with a transparent member, it is possible to suppress the loss of light of the backlight unit 5A and obtain high light utilization efficiency.
  • a configuration is adopted in which light is incident from the two end faces 21ea and 21eb facing the X-axis direction of the light guide plate 21, but the present invention is not limited to this.
  • a configuration in which light is incident only from one end face or light is incident from all four end faces may be employed.
  • the relationship between the position in the light guide plate 21 of light propagating in the light guide plate 21 and the light power density differs depending on the light source arrangement method, it is necessary to optimize the arrangement density of the micro optical elements 21d for each condition. There is.
  • FIG. FIG. 5 is a configuration diagram schematically showing a configuration of a liquid crystal display device 102 which is a transmission type display device according to the second embodiment of the present invention.
  • FIG. 6 is a schematic diagram of a planar light source 300 constituting the backlight unit 5B of the liquid crystal display device 102.
  • the backlight unit 5A of the liquid crystal display device 101 of the first embodiment includes white LEDs as the light source groups 20Ga and 20Gb
  • the backlight unit 5B of the liquid crystal display device 102 of the second embodiment includes the light source 30Ga
  • As light sources constituting 30 Gb a single color LED 30 a that emits blue light and a single color LED 30 b that emits red light are provided.
  • a phosphor sheet 38 in which a phosphor 37 that emits green light is applied to the light diffusion reflection sheet 36 is provided.
  • Components similar to those of the liquid crystal display device 101 described in Embodiment 1 are denoted by the same reference numerals, and description thereof is omitted.
  • the liquid crystal display device 102 includes a transmissive liquid crystal display element 10, an optical sheet 11 that is a first optical sheet, an optical sheet 12 that is a second optical sheet, and a surface light source device.
  • the constituent elements 10, 11, 12, 5B are stacked and arranged in the Z-axis direction.
  • the backlight unit 5B includes a light source group 30Ga, 30Gb, a light guide plate 31, and a phosphor sheet 38 in which a phosphor 37 that emits green light is applied to a light diffusion reflection sheet 36.
  • the phosphor sheet 38 is composed of a light diffuse reflection sheet 36 and a phosphor 37. Moreover, since the phosphor sheet 38 emits green light itself, it also functions as a second planar light source.
  • the light source groups 30Ga and 30Gb are arranged to face the light incident end faces 31ea and 31eb provided on both end faces in the X-axis direction of the light guide plate 31, respectively.
  • the light beams ILc and ILd emitted from the light source groups 30Ga and 30Gb are Light enters the light guide plate 31 from the light incident end surfaces 31ea and 31eb of the light guide plate 31 and propagates toward the center of the light guide plate 31.
  • the phosphor sheet 38 faces the surface 31 b of the light guide plate 31 opposite to the liquid crystal display element 10 and is arranged so as to be parallel to the light guide plate 31.
  • the light source groups 30Ga and 30Gb as shown in FIG.
  • LEDs 30a that emit blue monochromatic light and LEDs 30b that emit red monochromatic light are alternately arranged in the Y-axis direction at regular intervals.
  • the light guide plate 31 is arranged in parallel to the display surface 10f of the liquid crystal display element 10, and has fine optical elements 31d, ..., 31d on the surface (front surface) which is the surface on the liquid crystal display element 10 side.
  • FIG. 6 is a diagram showing a configuration when the planar light source 300 constituting the backlight unit 5B is viewed from the + Z-axis direction.
  • the light sources 30a, 30b,..., 30a, 30b constituting the light source groups 30Ga, 30Gb are arranged at equal intervals in the Y-axis direction so as to face the two light incident end surfaces 31ea, 31eb in the X-axis direction of the light guide plate 31. Yes.
  • the light source groups 30Ga and 30Gb are composed of a light source 30a and a light source 30b.
  • the light source 30a emits a blue light beam BL
  • the light source 30b emits a red light beam RL.
  • the light beam BL and the light beam RL are combined into light beams ILc and ILd.
  • Fine optical elements 31d,..., 31d are formed on the entire surface of the light guide plate 31 on the surface side in the + Z-axis direction. Since the micro optical element 31d exhibits the same optical action as the micro optical element 21d of the first embodiment, the light beams ILc and ILd emitted from the light source groups 30Ga and 30Gb are spread over the entire + Z-axis direction side of the light guide plate 31. , Converted into planar illumination lights BLc and BLd emitted in the ⁇ Z-axis direction.
  • the fine optical elements 31d,..., 31d are optical elements that change the traveling direction of the light beams ILc, ILd by reflection or refraction.
  • the light source groups 30Ga and 30Gb and the light guide plate 31 function as the first planar light source 300.
  • the fine optical elements 31d,..., 31d have a convex lens shape like the fine optical elements 21d,..., 21d formed on the light guide plate 21, and the X-axis of the light guide plate 31 from the two light incident end faces 31ea, 31eb. Arranged from sparse to dense toward the center of the direction. Thereby, the illumination lights BLc and BLd form planar light.
  • the light guide plate 31 has the same structure as the light guide plate 21 provided in the liquid crystal display device 101 of the first embodiment. Therefore, the light guide plate 31 acts similarly on the light beams ILc and ILd emitted from the light source groups 30Ga and 30Gb. Light rays ILc and ILd emitted from the light source groups 30Ga and 30Gb propagate through the light guide plate 31. At that time, the red light and the blue light are mixed, and the light beams ILc and ILd are mixed light beams.
  • the light beams ILc and ILd are converted into illumination lights BLc and BLd directed in the ⁇ Z-axis direction by the micro optical elements 31d,..., 31d formed on the surface of the light guide plate 31 in the + Z-axis direction.
  • the illumination lights BLc and BLd are first planar light in which the blue light beam BL and the red light beam RL are mixed.
  • the illumination lights BLc and BLd are emitted toward the phosphor sheet 38 from the back surface 31b of the light guide plate 31 in the ⁇ Z-axis direction.
  • Illumination light FL is emitted.
  • the green illumination light FL is second planar light.
  • the excitation light is light used for exciting the phosphor 37.
  • the illumination lights BLc and BLd are diffused by the surface of the phosphor 37 arranged on the + Z axis direction side of the phosphor sheet 38 or the light diffusion reflection sheet 36 arranged on the ⁇ Z axis direction side of the phosphor sheet 38. And reflected.
  • the reflected illumination lights BLc and BLd are mixed light of the blue light beam BL and the red light beam RL that are not used for exciting the phosphor 37, and the first planar light (illumination light BLc and BLd). Is emitted from the phosphor sheet 38 in the + Z-axis direction.
  • the first planar light (illumination light BLc, BLd) composed of the blue light beam BL and the red light beam RL is emitted from the phosphor 37 of the phosphor sheet 38. It is mixed with light (illumination light FL), becomes white illumination light, and is emitted in the + Z-axis direction.
  • illumination light FL emitted from the phosphor 37 of the phosphor sheet 38
  • the light beam emitted in the ⁇ Z-axis direction is diffused and reflected by the light diffusion reflection sheet 36 in the + Z-axis direction.
  • the light diffusion reflection sheet 36 for example, a light diffusion reflection sheet based on a resin such as polyethylene terephthalate or a light diffusion reflection sheet in which a metal is deposited on the surface of a substrate having a fine uneven shape is used. Can do.
  • the illumination lights FL, BLc, and BLd pass through the light guide plate 31, the optical sheet 12, and the optical sheet 11 and are emitted toward the back surface 10 b of the liquid crystal display element 10.
  • the blue and red light beams ILc and ILd emitted from the light source groups 30Ga and 30Gb may not be sufficiently mixed in the vicinity of the light incident end faces 31ea and 31eb.
  • the blue and red light beams ILc and ILd are converted into planar illumination lights BLc and BLd traveling in the ⁇ Z-axis direction by the micro optical elements 31d,. .
  • the illumination lights BLc and BLd emitted from the back surface 31b of the light guide plate 31 are diffused and reflected by the surface of the phosphor 37 of the phosphor sheet 38 or the reflection surface of the light diffusion reflection sheet 36, and again reflected on the light guide plate 31. Come back.
  • the illumination lights BLc and BLd propagate back and forth along an optical path parallel to the normal direction of the image display surface 10f of the liquid crystal display element 10, and are diffused by the phosphor sheet 38 in the optical path. Is a planar illumination light having a uniform in-plane luminance distribution.
  • the illumination light FL has an in-plane luminance distribution even when non-uniform blue light is incident on the phosphor 37.
  • the light is emitted from the phosphor 37 as uniform green planar light.
  • the first planar light composed of blue and red (illumination light BLc, BLd) and the green second planar light (illumination light FL) are mixed with each other, and the in-plane luminance distribution is uniform. It becomes white third planar light (illumination light ML) and illuminates the liquid crystal display element 10. Therefore, the liquid crystal display device 102 of this embodiment can provide a good image with reduced luminance distribution with a simple and small configuration.
  • the light source of the present embodiment employs LEDs 30a and 30b that directly emit red light and blue light with high luminous efficiency, while green light is obtained by exciting the phosphor with the blue light source 30a. .
  • LEDs 30a and 30b that directly emit red light and blue light with high luminous efficiency, while green light is obtained by exciting the phosphor with the blue light source 30a.
  • the illumination lights BLc and BLd emitted from the back surface 31b of the light guide plate 31 enter the phosphor 37, and then are reflected by the light diffusion reflection sheet 38 to be guided through the phosphor 37. Proceed toward the light plate 31. That is, the illumination lights BLc and BLd pass through the phosphor 37 twice. For this reason, the quantity which the fluorescent substance 37 light-emits with respect to the light quantity of the illumination lights BLc and BLd which injected into the fluorescent substance 37 can be increased.
  • the traveling direction of the light emitted by the phosphor 37 toward the ⁇ Z axis direction is efficiently changed to the liquid crystal display element 10 side.
  • the intensity of the green light emitted from the phosphor sheet 38 is the thickness of the phosphor 37 in the Z-axis direction or the minute optical element 31d in the XY plane relative to the intensity of the illumination lights ILc and ILd. ,..., 31d are adjusted in spatial density.
  • the phosphor has a characteristic that the luminous efficiency decreases as the temperature rises.
  • the phosphor 37 can be arranged at a position away from the light source groups 30Ga and 30Gb, the phosphor 37 is separated from the light source groups 30Ga and 30Gb serving as heat sources. It can be made less susceptible to the heat radiated.
  • the illumination lights BLc and BLd that excite the phosphor 37 are emitted toward the phosphor 37 as planar light, the power density of the illumination lights BLc and BLd that are excitation light incident on the phosphor 37 is set. Can be reduced.
  • the amount of illumination light BLc, BLd that hits the phosphor 37 per unit area can be reduced.
  • the fall of the luminous efficiency of the fluorescent substance 37 can also be suppressed by suppressing the temperature rise of the fluorescent substance 37.
  • the first planar light (illumination light BLc, BLd), which is a mixture of blue and red light, and the green second planar light (illumination light FL) emitted by the phosphor 37 are mixed and white.
  • the light source groups 30Ga and 30Gb include, for example, a light source 30a that emits a blue light beam BL having a peak near 450 nm and a light source 30b that emits a red light beam RL having a peak near 620 nm.
  • a part of the blue light beam BL emitted from the light source 30 a is absorbed by the phosphor 37, converted into light having a wavelength near, for example, 530 nm, and emitted from the phosphor 37.
  • the liquid crystal display device 102 of the present embodiment has a small amount of light emitted from the light source groups 30Ga and 30Gb in which the plurality of point light sources 30a, 30b,..., 30a, 30b are arranged on a straight line.
  • the light diffusion structure having a simple configuration with the number of parts can be used to convert the light into a uniform luminance distribution. Further, since the light diffusion structure is provided along the normal direction (Z-axis direction) of the image display plane (XY plane) of the liquid crystal display device 102, It is not necessary to arrange the light diffusion structure so as to be adjacent in the Y-axis direction. Thereby, the ratio of the area of the backlight unit 5B to the area of the image display plane 10f can be reduced.
  • the liquid crystal display device 102 in which the width of the bezel that is the cabinet portion surrounding the image display portion is narrowed while providing an image with good image quality. Further, since the light propagation part is designed with the thickness of the light guide plate 31, the liquid crystal display device 102 can be thinned. Furthermore, as light sources constituting the light source groups 30Ga and 30Gb, red and blue LEDs 30a and 30b having excellent monochromaticity and luminous efficiency, and a phosphor 37 that emits green light using the blue light as excitation light are provided. Therefore, it is possible to provide the liquid crystal display device 102 that achieves low power consumption while having a wide color reproduction range.
  • the light sources 30a and 30b of the backlight unit 5B of the present embodiment both employ LEDs, but the present invention is not limited to this.
  • a laser light source even when a laser light source is employed, a high effect can be obtained with respect to the uniformity of the in-plane luminance distribution, and the adoption of a laser light source with superior monochromaticity can be achieved. It is possible to further expand the color reproduction range.
  • the light source group 30Ga, 30Gb is composed of a single color LED and a red LED that emit ultraviolet light having an ultraviolet wavelength band, instead of the light sources 30a, 30b, and absorbs the ultraviolet light to change from blue to green. It is good also as a structure which employ
  • FIG. 7 is a configuration diagram schematically showing a configuration of a liquid crystal display device 103 which is a transmissive image display device according to the third embodiment of the present invention.
  • FIG. 8 is a diagram showing a schematic configuration of the first planar light source 301 constituting the backlight unit 5C of the liquid crystal display device 103.
  • FIG. 9 is a diagram showing a schematic configuration of another planar light source 400a constituting the backlight unit 5C
  • FIG. 10 shows a schematic configuration of still another planar light source 400b constituting the backlight unit 5C.
  • the liquid crystal display device 102 of the second embodiment includes the backlight unit 5B that emits white planar light (illumination light ML), whereas the liquid crystal display device 103 of the third embodiment has a blue-green color.
  • the backlight unit 5C includes a planar light source 301 that emits planar light and a planar light sources 400a and 400b that emit red planar light. 7 and 8, the same reference numerals are given to the same components as those of the liquid crystal display devices 101 and 102 described in the first and second embodiments, and the description thereof is omitted.
  • the liquid crystal display device 103 includes a transmissive liquid crystal display element 10, an optical sheet 11 that is a first optical sheet, an optical sheet 12 that is a second optical sheet, and a backlight unit. 5C, and these components 10, 11, 12, and 5C are stacked in the Z-axis direction.
  • the liquid crystal display device 103 further includes a liquid crystal display element driving unit (not shown) that drives the liquid crystal display element 10 and a light source driving unit (not shown) that drives the light source groups 32Ga, 32Gb, 40Ga, and 40Gb included in the backlight unit 5C.
  • a liquid crystal display element driving unit (not shown) that drives the liquid crystal display element 10
  • a light source driving unit (not shown) that drives the light source groups 32Ga, 32Gb, 40Ga, and 40Gb included in the backlight unit 5C.
  • the operations of the liquid crystal display element driving unit and the light source driving unit are controlled by a control unit (not shown).
  • the control unit performs image processing on a video signal supplied from a signal source (not shown) to generate a control signal, and supplies the control signal to the liquid crystal display element driving unit and the light source driving unit.
  • the light source driving unit drives the light source groups 32Ga, 32Gb, 40Ga, and 40Gb in accordance with control signals from the control unit, and emits light from these light source groups 32Ga, 32Gb, 40Ga, and 40Gb, respectively.
  • the backlight unit 5C includes light source groups 32Ga and 32Gb that emit blue light, a light guide plate 31, and a phosphor sheet 38 in which a phosphor 37 that emits green light is applied to a light diffusion reflection sheet 36.
  • the backlight unit 5C includes light source groups 40Ga and 40Gb that emit red light, and two light guide plates 41 and 42 that generate red planar light.
  • the light source groups 32Ga and 32Gb are arranged to face the light incident end faces 31ea and 31eb provided on both end faces in the X-axis direction of the light guide plate 31, respectively.
  • 32Gb consists of only the blue LED light sources 30a, ..., 30a.
  • Light rays emitted from the light source groups 32Ga and 32Gb are incident on the inside of the light guide plate 31 from the light incident end surfaces 31ea and 31eb on both end surfaces of the light guide plate 31, and propagate toward the center of the light guide plate 31.
  • the micro optical elements 31d,..., 31d convert light propagating through the light guide plate 31 into planar illumination light that travels in the ⁇ Z-axis direction over the entire surface of the light guide plate 31.
  • Part of the illumination light excites the phosphor 37 to generate green planar illumination light, and the other part of the illumination light is reflected in the direction of the light guide plate 31 by the light diffusion reflection sheet 36.
  • the light guide plate 31 transmits the light incident from the phosphor sheet 38. As a result, blue-green illumination light is emitted from the front surface of the light guide plate 31.
  • the blue light beams emitted from the light source groups 32Ga and 32Gb are illuminated toward the ⁇ Z axis direction by the micro optical elements 31d,..., 31d formed on the surface of the light guide plate 31 in the + Z axis direction. Converted to light. This illumination light is emitted from the back surface 31 b of the light guide plate 31 toward the phosphor sheet 38.
  • Part of the blue illumination light emitted toward the phosphor sheet 38 is used as excitation light for the phosphor 37 constituting the phosphor sheet 38, so that green illumination light is emitted from the phosphor sheet 38. .
  • This green illumination light is the second planar light.
  • the blue illumination light that was not used for excitation of the phosphor sheet 38 was arranged on the surface of the phosphor 37 arranged on the + Z axis direction side of the phosphor sheet 38 or on the ⁇ Z axis direction side of the phosphor sheet 38.
  • the light is reflected by the light diffusion reflection sheet 36 and is emitted from the phosphor sheet 38 as first planar light.
  • the blue illumination light (first planar light) and the green illumination light (second planar light) emitted from the phosphor 37 of the phosphor sheet 38 are mixed with each other to produce a blue-green illumination.
  • Light is emitted in the + Z-axis direction.
  • the planar light emitted from the phosphor 37 of the phosphor sheet 38 the light emitted in the ⁇ Z-axis direction is diffused and reflected by the light diffusion reflection sheet 36 in the + Z-axis direction.
  • excitation light is light used for excitation of a fluorescent substance.
  • the light diffusion reflection sheet 36 for example, a light diffusion reflection sheet based on a resin such as polyethylene terephthalate or a light diffusion reflection sheet in which a metal is deposited on the surface of a substrate having a fine uneven shape is used. Can do.
  • the blue-green illumination light radiated from the phosphor sheet 38 passes through the light guide plate 31 and is mixed with the red illumination lights DLa and DLb by the light guide plates 41 and 42 to form white illumination light.
  • the white illumination light passes through the optical sheet 12 and the optical sheet 11 and illuminates the back surface 10b of the liquid crystal display element 10.
  • the light guide plates 41 and 42 convert the red light beams ILe and ILf emitted from the light source groups 40Ga and 40Gb into illumination lights DLa and DLb directed in the + Z-axis direction, respectively, and emit them toward the back surface 10b of the liquid crystal display element 10. These illumination lights DLa and DLb are transmitted through the optical sheet 12 and the optical sheet 11 to illuminate the back surface 10b of the liquid crystal display element 10.
  • planar light source 400a and the planar light source 400b are diagrams schematically showing the configuration of the planar light source 400a and the planar light source 400b.
  • the planar light source 400a of FIG. 9 includes a light guide plate 41 and light source groups 40Ga and 40Gb arranged in parallel to the display surface 10f of the liquid crystal display element 10.
  • the planar light source 400b in FIG. 10 includes a light guide plate 42 and a light source 40b arranged in parallel to the display surface 10f of the liquid crystal display element 10.
  • the planar light source 400a is a third planar light source, and emits fourth planar light (illumination light DLa).
  • the planar light source 400b is a fourth planar light source, and emits fourth planar light (illumination light DLb).
  • FIG. 9 is a schematic view of the planar light source 400a viewed from the ⁇ Z axis direction side
  • FIG. 10 is a schematic view of the planar light source 400b viewed from the ⁇ Z axis direction side.
  • the illumination light DLa and the illumination light DLb are fourth planar lights.
  • the light sources 40a,..., 40a constituting the light source group 40Ga included in the planar light source 400a are disposed to face the light incident end surface 41ea that is the end surface on the ⁇ X axis direction side of the light guide plate 41.
  • the Y axis It is arranged at equal intervals along the direction.
  • the light guide plate 41 included in the planar light source 400a is a plate-shaped member made of a transparent material, and is a surface on the opposite side of the liquid crystal display element 10 and a fine optical element on the back surface that is a surface on the ⁇ Z-axis direction side. 41d has an optical element portion Ra on which 41d is formed.
  • the light beam ILe emitted from the light source group 40Ga enters the light guide plate 41 from the light incident end face 41ea of the light guide plate 41, and propagates through the light guide plate 41 while being totally reflected.
  • the light sources 40b,..., 40b constituting the light source group 40Gb are arranged to face the light incident end face 42eb which is the end face on the + X axis direction side of the light guide plate 42.
  • the light guide plate 42 included in the planar light source 400b is a plate-like member made of a transparent material.
  • the light guide plate 42 is a surface opposite to the liquid crystal display element 10 and has a fine surface on the back side that is the surface on the ⁇ Z axis direction side.
  • the optical element portion Rb is formed with the optical elements 42d,.
  • the light emitted from the light source group 40Gb enters the light guide plate 42 from the light incident end face 42eb of the light guide plate 42, and propagates in the light guide plate 42 while being totally reflected.
  • the micro optical elements 41d and 42d function as optical elements that change the traveling directions of the light beams ILe and ILf by reflecting or refracting the light beams ILe and ILf, respectively.
  • the light source groups 40Ga and 40Gb included in the planar light source 400a and the planar light source 400b employ laser light sources having the same characteristics, and intervals between the light sources 40a,..., 40a, 40b,. , 40a, 40b,..., 40b have the same arrangement direction, angle, etc. with respect to the light incident end faces 41ea, 42eb.
  • the backlight unit 5C includes two planar light sources 400a and 400b having the same characteristics.
  • the shape of the optical element portion Ra of the one planar light source 400a and the shape of the optical element portion Rb of the other planar light source 400b are rotated by 180 degrees with respect to the normal to the display surface 10f of the liquid crystal display element 10. It is in.
  • These planar light sources 400a and 400b are stacked and arranged so that the four side surfaces of the light guide plate 41 and the four side surfaces of the light guide plate 42 are aligned in the Z-axis direction.
  • the light source group 40Ga included in the planar light source 400a and the light source group 40Gb included in the planar light source 400b are arranged to face each other in the X-axis direction, and the light source group 40Ga emits light toward the + X-axis direction, The light source group 40Gb emits light in the ⁇ X axis direction. For this reason, the traveling directions of the light beams ILe and ILf emitted from the light source groups 40Ga and 40Gb are opposite to each other.
  • the illumination lights DLa and DLb emitted from the planar light sources 400a and 400b travel toward the back surface 10b of the liquid crystal display element 10.
  • the backlight unit 5C in the present embodiment has a configuration in which the two planar light sources 400a and 400b are stacked in the traveling direction of the illumination lights DLa and DLb (+ Z axis direction) as described above. For this reason, when the light source groups 40Ga and 40Gb included in the backlight unit 5C are turned on, the illumination light DL emitted from the backlight unit 5C is the illumination lights DLa and DLb emitted from the two planar light sources 400a and 400b. It has been added.
  • the in-plane luminance distribution in the XY plane of the illumination light DL emitted from the backlight unit 5C is the sum of the in-plane luminance distributions in the XY plane of the two planar light sources 400a and 400b. Become.
  • the light guide plates 41 and 42 are formed of a transparent member, for example, a plate member having a thickness of 2 mm. As shown in FIGS. 7, 9, and 10, the optical element portions Ra and Rb have a hemispherical convex shape (hereinafter referred to as a convex lens shape) on the back surface that is the surface opposite to the liquid crystal display element 10. , 41d, 42d,..., 42d are formed. These micro optical elements 41d and 42d convert the light beams ILe and ILf propagating through the light guide plates 41 and 42 into illumination lights DLa and DLb traveling in the direction of the back surface 10b of the liquid crystal display element 10 (+ Z axis direction). To do.
  • a convex lens shape hemispherical convex shape
  • the light beams ILe and ILf incident on the light guide plates 41 and 42 from the light incident end surfaces 41ea and 42eb, respectively, are repeatedly reflected inside the light guide plates 41 and 42 by total reflection at the interface between the light guide plates 41 and 42 and the air layer. Progress in the axial direction.
  • the light beams ILe and ILf there are light beams that do not satisfy the total reflection condition at the interface between the front surfaces of the light guide plates 41 and 42 and the air layer.
  • the light rays are emitted from the front surfaces of the light guide plates 41 and 42 toward the back surface 10b of the liquid crystal display element 10.
  • the arrangement density of 42d,..., 42d (that is, the number per unit area and the size thereof) varies spatially. Thereby, it is possible to control the in-plane luminance distribution of the illumination lights DLa and DLb emitted from the light guide plates 41 and 42.
  • the arrangement density of the micro optical elements 41d,..., 41d increases as the distance from the light incident end surface 41ea of the light guide plate 41 in the traveling direction of the light beam ILe (the + X-axis direction in FIG. 9). A structure that changes is adopted.
  • the arrangement density of the micro optical elements 42d,..., 42d changes with distance from the light incident end face 42eb of the light guide plate 42 in the traveling direction of the light beam ILf ( ⁇ X axis direction in FIG. 10). Structure is adopted.
  • the micro optical element 41 d is not arranged in the vicinity of the light incident end face 41 ea in the light guide plate 41, but from the position of the approximately center of the light guide plate 41 in the X-axis direction. It is provided in the region Ra up to the end surface facing the light incident end surface 41ea.
  • the arrangement density continuously changes from sparse to dense as it goes from the vicinity of the center position in the X-axis direction toward the end face of the light guide plate 41.
  • the micro optical element 42 d is not disposed in the vicinity of the light incident end surface 42 eb in the light guide plate 42, and the light incident end surface from the position about the center of the light guide plate 42 in the X-axis direction. It is provided in the region Rb up to the end surface facing 42eb.
  • the arrangement density continuously changes from sparse to dense as it goes from the vicinity of the center position in the X-axis direction toward the end face of the light guide plate 42.
  • the surface shape of the micro optical elements 41d and 42d for example, a convex lens shape having a curvature of about 0.15 mm and a maximum height of about 0.005 mm is employed, as with the micro optical elements 21d and 31d of the light guide plates 21 and 31. it can.
  • the refractive index of the micro optical elements 41d and 42d may be about 1.49.
  • the light guide plates 41 and 42 and the micro optical elements 41d and 42d can be made of acrylic resin, but are not limited to this material. As long as the material has good light transmittance and excellent moldability, other resin materials such as polycarbonate resin or glass material may be used instead of acrylic resin.
  • the surface shapes of the micro optical elements 41d and 42d are convex lens shapes, but the present invention is not limited to this.
  • the micro optical elements 41d and 42d have a structure in which the light beams ILe and ILf traveling in the X-axis direction through the light guide plates 41 and 42 are totally reflected in the Z-axis direction and emitted toward the back surface 10b of the liquid crystal display element 10.
  • other shapes may be used.
  • a fine optical element having a prism shape or a random concavo-convex pattern such as sandblast may be adopted.
  • a convex lens shape there is an advantage that light can be refracted with a transparent structure, and since it has a simpler shape than a structure such as a prism, it is easy to manufacture. Further, even when the light guide plates 41 and 42 are increased in size, the light guide plates 41 and 42 can be easily coped with because the light guide plates 41 and 42 can be manufactured by printing. Laser light can be refracted in the Z-axis direction even with random uneven shapes such as sandblasting, but in the case of a convex lens shape, a convex shape can be designed, so a planar light source that realizes a uniform luminance distribution There is an advantage that the design of 400a and 400b is easy.
  • the thickness of the light guide plates 41 and 42 is 2 mm, but the present invention is not limited to this.
  • the laser light source is a light source having a small light emitting surface area and high directivity, it is possible to obtain high optical coupling efficiency even for a light guide plate having a small thickness.
  • the divergence angle is 40 degrees with the full width at half maximum in the fast axis direction and 10 degrees with the full width at half maximum in the slow axis direction.
  • the laser light sources of the light source groups 40Ga and 40Gb are preferably arranged so that the fast axis direction thereof is parallel to the short side direction of the light incident end faces 41ea and 42eb of the light guide plates 41 and 42. .
  • the light diameters of the light beams ILe and ILf emitted from the light source groups 40Ga and 40Gb are extremely small with respect to the size of the light incident end faces 41ea and 42eb in the Y-axis direction.
  • Fine optical elements 41d and 42d are not formed in regions corresponding to the light propagation portions Pa and Pb provided in the vicinity of the light incident end surfaces 41ea and 42eb of the light guide plates 41 and 42, respectively.
  • the light beams ILe and ILf can propagate while totally reflecting a sufficient optical distance in the light propagation portions Pa and Pb. Therefore, the light beams ILe and ILf are spread by their divergence angles and spatially overlap with other adjacent light beams to form linear light having a uniform luminance distribution in the Y-axis direction, that is, linear light.
  • FIG. 11 is a conceptual diagram for explaining that light beams emitted from two adjacent light sources become linear light by propagating a certain optical distance.
  • the luminance distribution 60 in the Y-axis direction of a light beam emitted from a single light source at an arbitrary position in the X-axis direction is caused by the Gaussian-shaped angular luminance distribution originally possessed by the light beam.
  • the brightness is high, and the shape is such that the brightness rapidly decreases as the distance from the center increases. Therefore, when a single light beam enters the optical element unit, the luminance distribution of the light beam is reflected in the in-plane luminance distribution of the illumination light emitted from the light guide plate, thereby causing uneven luminance distribution.
  • a linear light source having a uniform luminance distribution in the light source arrangement direction that is the Y-axis direction can be created.
  • a single ray having the luminance distribution 60 in FIG. 11 and a single ray having the luminance distribution 61 are superimposed, the distributions are averaged, and a uniform luminance distribution such as the luminance distribution 62 is obtained.
  • the light distribution can be averaged by spatially superimposing a plurality of light beams, so that the luminance distribution is uniform in the light source array direction. It becomes possible to create a simple linear light source.
  • the light guide plates 41 and 42 included in the planar light sources 400a and 400b according to the third embodiment include light propagation portions Pa and Pb that propagate until the light beams ILe and ILf enter the micro optical elements 41d and 42d.
  • These light propagation portions Pa and Pb are necessary for the light beams ILe and ILf to be sufficiently spread spatially in the arrangement direction (Y-axis direction) of the light sources 40a,..., 40a, 40b,. Has optical distance. For this reason, the light beams ILe and ILf can be incident on the optical element portions Ra and Rb on which the micro optical elements 41d and 42d are formed after becoming highly uniform linear light.
  • the light sources 40a,..., 40a, 40b,..., 40b constituting the light source groups 40Ga, 40Gb emit light having the same divergence angle and angular luminance distribution, and are arranged at equal intervals. Therefore, linear light with higher uniformity of luminance distribution can be obtained.
  • the light beams ILe and ILf that enter the optical element portions Ra and Rb as linear light are partially reflected internally by the micro optical elements 41d and 42d on the back surfaces of the light guide plates 41 and 42. Is converted into illumination light DLa and DLb and emitted from the surface of the light guide plates 41 and 42 toward the back surface 10b of the liquid crystal display element 10.
  • the light beams ILe and ILf incident on the micro optical elements 41d and 42d are uniform linear light in the arrangement direction (Y-axis direction) of the light sources 40a, ..., 40a, 40b, ..., 40b. , 40a, 40b,..., 40b illuminate the liquid crystal display element 10 as uniform illumination light DL without causing uneven luminance distribution.
  • the planar light sources 400a and 400b convert the light beams ILe and ILf emitted from the light sources 40a and 40b, which are point light sources, into linear light in the X-axis direction, which is the traveling direction of the light beams ILe and ILf, respectively.
  • Light propagation portions Pa and Pb are provided.
  • the planar light sources 400a and 400b have areas where the illumination lights DLa and DLb are not emitted.
  • the planar light sources 400a and 400b are stacked and arranged so as to supplement regions (light propagation portions Pa and Pb) that do not emit the illumination lights DLa and DLb. That is, the area where the planar light source 400a does not emit light and the area where the planar light source 400b emits light are stacked in the Z-axis direction, and the area where the planar light source 400b does not emit light and the area where the planar light source 400a emits light. They are stacked in the Z-axis direction. For this reason, the combination of the planar light source 400a and the planar light source 400b can emit illumination light from the entire surface.
  • the fine optical elements 41d which determine the respective luminance distributions such that the luminance distributions in the X-axis direction of the planar light source 400a and the planar light source 400b are added to make the luminance distribution uniform.
  • the arrangement density in the X-axis direction of 42d is optimized.
  • FIG. 12 is a graph showing a calculation result by simulation of a one-dimensional luminance distribution in the X-axis direction of the illumination lights DLa and DLb emitted from the planar light source 400a and the planar light source 400b. More specifically, FIG. 12 adds the one-dimensional luminance distribution 50 in the X-axis direction of the planar light source 400a, the one-dimensional luminance distribution 51 in the X-axis direction of the planar light source 400b, and both luminance distributions 50 and 51. It is a graph which shows the calculation result by simulation with the combined one-dimensional luminance distribution 52 in the X-axis direction.
  • the one-dimensional luminance distribution 50 of the illumination light DLa emitted from the planar light source 400a is the center of the light guide plate 41 in the X-axis direction from the light incident end face 41ea arranged on the ⁇ X-axis direction side. No light is emitted near the position.
  • the luminance gradually increases from the vicinity of the center position of the light guide plate 41 in the X-axis direction toward the + X-axis direction, and maintains a constant luminance in the vicinity of the end surface facing the light incident end surface 41ea in the + X-axis direction. .
  • the one-dimensional luminance distribution 51 of the illumination light DLb emitted from the planar light source 400b has a luminance distribution that is opposite to the one-dimensional luminance distribution 50 of the planar light source 400a, and light incident in the + X axis direction.
  • No light is emitted from the end face 42eb to the vicinity of the center position of the light guide plate 42 in the X axis direction, and the luminance gradually increases from the vicinity of the center position of the light guide plate 42 in the X axis direction toward the -X axis direction.
  • a constant luminance is maintained in the vicinity of the end surface facing the light incident end surface 42eb in the ⁇ X axis direction.
  • the illumination light DLa and the illumination light DLb are emitted so as to overlap in the vicinity of the center of the light guide plates 41 and 42 in the X-axis direction.
  • the amount of light emitted toward the liquid crystal display element 10 is gradually increased by changing the arrangement of the micro optical elements 41d and 42d from sparse to dense.
  • the amount of light added together can be easily made the same as that of the other portions, and the illumination light DLa of the planar light source 400a and the planar light source It is possible to suppress a decrease in the amount of light at the joint with the illumination light DLb of 400b or suppress unevenness in luminance distribution due to an increase in the amount of light.
  • FIG. 13 shows the result of actually measuring the in-plane luminance distribution of the illumination light emitted from the planar light sources 400a and 400b manufactured according to the configuration of the present embodiment. As can be seen from FIG. 13, in the configuration in which the two planar light sources 400a and 400b are stacked in the Z-axis direction, illumination light having excellent uniformity in the traveling direction of the light beam (X-axis direction) can be obtained.
  • the laser light source 80 (40a) included in the light source group 40Ga and the laser light source 81 (40a) adjacent to the laser light source 81 (40a) in the Y-axis direction will be described as an example, and the light propagation portion Pa provided in the light guide plate 41 will be described in detail.
  • FIG. 14 is a conceptual diagram conceptually showing optical paths of laser beams 80p and 81p that are emitted from adjacent laser light sources 80 and 81 provided in the light source group 40Ga and are incident on the light guide plate 41 from the light incident end face 41ea.
  • FIG. 15 shows one-dimensional luminance distributions 80q and 81q in the Y-axis direction of the laser beams 80p and 81p propagated through the light propagation portion Pa when the optical distance in the X-axis direction is X, and lines generated by adding them together. It is a graph which shows the one-dimensional luminance distribution 82q of light of a shape.
  • the laser light sources 80 and 81 are adjacent to each other with a distance d between the respective light emitting points in the Y-axis direction, and are disposed so as to face the light incident end face 41ea of the light guide plate 41.
  • the distance between the light emitting surfaces of the laser light source 80 and the laser light source 81 and the light incident end surface 41ea is set to a distance f.
  • the laser light sources 80 and 81 have the same characteristics as each other, and the angular luminance distributions of the substantially Gaussian shape having a half-value half-angle ⁇ in the XY plane of the laser beams 80p and 81p emitted from them have the same shape.
  • the half value half angle means a beam divergence angle (half angle) corresponding to a point at which the light intensity is half the peak value in the light intensity distribution of the laser beam.
  • Laser beams 80p and 81p emitted from the laser light sources 80 and 81 enter the light guide plate 41 from the light incident end face 41ea and propagate through the light propagation portion Pa.
  • the optical distance X in the X-axis direction of the light propagation part Pa is defined by the following equation (1).
  • d is the distance between the light emitting points of the laser light sources 80 and 81
  • f is the distance between the emission surface of the laser light sources 80 and 81 and the light incident end face 41ea
  • ⁇ is emitted from the laser light sources 80 and 81.
  • ⁇ is the half-value half-angle of the divergence angle in the XY plane of the laser beams 80p and 81p propagating in the light guide plate 41.
  • the half value half angle ⁇ in the light guide plate 41 is defined by the following equation (2).
  • the refractive index of the layer that propagates before the laser beams 80p and 81p emitted from the laser light sources 80 and 81 enter the light guide plate 41a is n 1
  • the refractive index of the light guide plate 41 is n 2 .
  • the laser beam 80p and the laser beam 81p are half the peak luminance existing on the optical axes 80a and 81a in the X axis direction in the luminance distribution in the Y axis direction.
  • the optical distance X necessary for having an intersection at a position having luminance is determined.
  • the optical distance determined by the equations (1) and (2).
  • a bright portion which is a bright portion existing on the optical axes 80a and 81a of the laser beams 80p and 81p exists between the optical axis 80a of the laser beam 80p and the optical axis 81a of the laser beam 81p. Since there is a dark part which is a dark part, uneven luminance distribution occurs in the Y-axis direction.
  • the laser beams 80p and 81p propagate through the light propagation part Pa having the optical distance X defined by the expressions (1) and (2), thereby minimizing the size of the light propagation part Pa. It is possible to generate linear light with a uniform luminance distribution in the Y-axis direction while suppressing the amount of light.
  • the micro optical element 41d is provided in a region from the end in the + X-axis direction of the light propagation portion Pa to the end in the + X-axis direction of the light guide plate 41, and the arrangement density is sparsely and densely continuous in the + X-axis direction. It is formed so as to change.
  • the structure and characteristics of the micro optical element 41d are as described above.
  • the light guide plate 41 has been described here, the light guide plate 42 is similarly provided with a light propagation part Pb that satisfies the expressions (1) and (2), and the light beam ILf is a linear light with high uniformity. Is incident on the optical element portion Rb in which the fine optical element 42d is formed, and illuminates the liquid crystal display element 10 as planar light (illumination light DLb) having a uniform in-plane luminance distribution.
  • planar light sources 400a and 400b each having the light guide plate 41 and the light guide plate 42 are planar light sources having a highly uniform in-plane luminance distribution. In the illumination light produced by these planar light sources 400a and 400b, the luminance distribution unevenness is suppressed. Therefore, it is possible to provide the high-quality liquid crystal display device 103 in which display unevenness is suppressed.
  • the light propagation portions Pa and Pb in an area required for converting a laser beam emitted from a laser light source that is a point light source into a linear laser beam correspond to an effective image display area. It can be provided in the region. Accordingly, it is not necessary to provide a light propagation part around the planar light source part while securing a sufficient optical distance for the laser beam to propagate, so that the image display plane (XY plane) of the liquid crystal display device 103 is obtained. It is possible to reduce the ratio of the area of the backlight device 9 to that area. That is, it is possible to realize the liquid crystal display device 103 in which the width of the bezel that is the cabinet portion surrounding the image display portion is narrowed while providing an image with good image quality. Further, since the light propagation part is designed with the thickness of the light guide plate, the liquid crystal display device 103 can be thinned.
  • the laser beam is necessary to spatially overlap with other laser beams that are closer to each other due to the divergence angle that the laser beam itself has to form a linear laser beam. Since a sufficient optical distance as a propagation distance can be provided, illumination light with a uniform in-plane luminance distribution can be generated. Therefore, even when a point light source and a highly directional laser light source are employed as a side light type or edge light type light source, a liquid crystal display device capable of displaying a good image with reduced luminance distribution can be provided. .
  • the present embodiment a simple configuration is realized by effectively using the effective image display area of the liquid crystal display device 103, and the backlight unit 5 ⁇ / b> C is provided for the effective image display area of the liquid crystal display device 103. It can be realized without increasing the size.
  • the light propagation part Pa and the optical element part Ra are provided on the single light guide plate 41, and the light propagation part Pb and the optical element part Rb are also provided on the single light guide plate 42. . Therefore, the light propagation part and the optical element part are composed of individual light guide plates, and compared with the case where they are used in combination, there is less light loss, the light utilization efficiency is improved, and the number of parts is reduced and assembled. Improves.
  • the plurality of planar light sources 400a and 400b having the same characteristics are employed, but the present invention is not limited to this.
  • the third embodiment realizes illumination light having a uniform in-plane luminance distribution by adding together illumination light emitted from the plurality of planar light sources 301, 400a, and 400b in the XY plane. As long as this is achieved, the in-plane luminance distribution of illumination light emitted from a plurality of planar light sources may be different.
  • the two sets of planar light sources 400a and 400b including a laser light source are stacked.
  • the present invention is not limited to this configuration.
  • the illumination light emitted from a plurality of planar light sources is added together on the XY plane, the illumination light that uniformly illuminates the entire liquid crystal display element 10 is generated. It is good also as a structure which laminated
  • the illumination light emitted from a plurality of planar light sources can be combined in the XY plane direction to achieve a backlight unit with a uniform in-plane luminance distribution.
  • Any in-plane luminance distribution may be used.
  • two or more sets of planar light sources may be stacked.
  • the light guide plate included in each planar light source is preferably configured so that a light propagation portion is provided in the vicinity of the light incident end surface. .
  • This light propagation part is an optical distance required for the light emitted from the laser light source to spatially overlap with the light emitted from the other adjacent laser light sources, and the luminance distribution becomes uniform in the arrangement direction of the laser light sources. have.
  • the light propagation part does not have a fine optical element or the like, and the laser beam propagates while being totally reflected in the light propagation part. For this reason, the laser beam propagated to the optical element portion on which the fine optical element is formed is linear light. For this reason, uneven brightness distribution of illumination light that is refracted by the micro optical element and emitted from the surface of the light guide plate toward the back surface 10b of the liquid crystal display element 10 is suppressed. Therefore, a high-quality liquid crystal display device with little display unevenness can be provided.
  • the laser light source arrangement method such as the arrangement interval of light sources, the arrangement direction and angle of the light guide plate with respect to the light incident end face.
  • the light incident end face of the laser light source is the end face on the short side of the liquid crystal display element 10, the optical distance of the laser beam can be increased efficiently, and the in-plane luminance distribution is more uniform. It becomes easy to obtain illumination light with excellent properties.
  • the laser light source propagates a sufficiently long optical distance in the light guide plate while performing multiple reflections, and a plurality of laser light sources are used in a spatially overlapping manner.
  • speckle noise random spot-like pattern appearing on the observation surface due to mutual interference of light
  • the backlight unit 5C includes the light source groups 32Ga and 32Gb, the light guide plate 31, and the phosphor sheet 38.
  • the light source groups 32Ga and 32Gb are disposed so as to oppose the light incident end surfaces 31ea and 31eb on both end surfaces in the X-axis direction of the light guide plate 31, and the light beams emitted from the light source groups 32Ga and 32Gb are both end surfaces of the light guide plate 31. From the light incident end faces 31ea and 31eb. As shown in FIG.
  • the light source group 32Ga, 32Gb includes a plurality of LED light sources 30a,..., 30a that emit blue light having a blue Lambertian angular intensity distribution arranged in the Y-axis direction at regular intervals.
  • the light incident on the light guide plate 31 is totally reflected on the inner surface by the micro optical elements 31d,..., 31d provided on the surface of the light guide plate 31 having the same structure as that of the second embodiment, and fluorescent from the back surface 31b of the light guide plate 31. It is converted into illumination light that is blue planar light emitted toward the body sheet 38.
  • the phosphor sheet 38 emits green light.
  • the remaining blue illumination light is diffused and reflected in the + Z-axis direction by the phosphor 37 disposed on the surface of the phosphor sheet 38 or the light diffusion reflection sheet 36 disposed on the back surface of the phosphor sheet 38. Is done.
  • the blue illumination light that is the first planar light and the green illumination light that is the second planar light are mixed and emitted as blue-green illumination light toward the liquid crystal display element 10.
  • the blue light as the excitation light can be efficiently converted into green light, and the phosphor It is possible to suppress a decrease in reliability and a decrease in light emission efficiency due to the temperature rise.
  • the light guide plates 41 and 42 laminated on the + Z-axis direction side of the light guide plate 31 are the micro optical elements 41d, which are also formed of the transparent member on the back surface of the plate member formed of the transparent member. 42d.
  • the blue-green illumination light emitted from the front surface of the light guide plate 31 is less susceptible to optical influences such as absorption and reflection when passing through the light guide plates 41 and 42. Therefore, the light loss of blue-green illumination light irradiated from the front surface of the light guide plate 31 is suppressed, and the light is efficiently used as illumination light for illuminating the liquid crystal display element 10.
  • the blue-green illumination light and the red illumination lights DLa and DLb emitted from the light guide plates 41 and 42 are mixed to form white illumination light.
  • the light source groups 32Ga and 32Gb are composed of light sources that emit blue light having a peak near 450 nm, for example. A part of the blue light beam is used as light for exciting the phosphor 37 of the phosphor sheet 38 having a peak near 530 nm and also used as blue illumination light for illuminating the liquid crystal display element 10.
  • the light source groups 32Ga and 32Gb and the phosphor sheet 38 for generating blue-green illumination light use the light source groups 32Ga and 32Gb as excitation light sources, and the phosphor 37 of the phosphor sheet 38 emits blue and green light. Can also be adopted.
  • a colorful image with a wide color reproduction range is provided by adopting a laser light source, an LED, and a monochromatic phosphor excellent in monochromaticity as a light source. can do.
  • a laser having a very high color purity is employed as a red light source that has the highest human sensitivity to color differences.
  • Direct emission LEDs and lasers have low green emission efficiency. Therefore, a phosphor with high luminous efficiency was adopted as the green light source.
  • an LED with high luminous efficiency as the blue light source a liquid crystal display device capable of vivid color expression with low power consumption can be obtained.
  • the liquid crystal display device 103 includes an optical structure that optimally diffuses light for each light source having different light directivities, and thus provides an image with reduced luminance distribution unevenness. Is possible. More specifically, light emitted from the light source groups 32Ga and 32Gb including LEDs that emit light having directivity is diffused by the thickness of the light guide plate 31 and the light diffusion reflection structure of the phosphor sheet 38. Light emitted from the light source groups 40Ga and 40Gb including a laser light source having higher directivity than the LED is diffused by the light propagation portions Pa and Pb having an optical distance about half of the effective image display area. With the above configuration, a liquid crystal display device that realizes high-quality image display that sufficiently diffuses directional light and suppresses uneven luminance distribution is realized without increasing the size of the liquid crystal display device 103.
  • the light source driving unit is individually controlled by the control unit, and the luminance of the red illumination lights DLa and DLb emitted from the light guide plates 41 and 42 and the light guide plate 31 are emitted.
  • the ratio of the brightness of the blue-green illumination light can be adjusted. For this reason, it is also possible to realize low power consumption by adjusting the light emission amount of each planar light source in accordance with the ratio of each color luminance required for the video signal.
  • the intensity of the green light emitted from the phosphor sheet 38 is the thickness of the phosphor 37 in the Z-axis direction or the fine optical element 31d with respect to the XY plane relative to the intensity of the blue-green illumination light. Spatial density is adjusted.
  • the planar light source 301 including green light with high luminance is disposed at a position farthest from the liquid crystal display element 10. This arrangement suppresses the influence of stray light, thereby suppressing the uneven luminance distribution caused by the stray light, thereby reducing the display unevenness of the liquid crystal display element 10 and improving the contrast.
  • the planar light source 301 that emits green light at a position farthest from the liquid crystal display element 10, even when there is a portion with high luminance in the planar light source due to stray light, the other light guide plates 41, 42 and the fine optical elements 41d and 42d, unevenness in luminance distribution is reduced by diffusion and divergence due to light refraction and the like.
  • unevenness in luminance distribution can be suppressed by the divergence angle of the light. Note that stray light is undesirable light generated by internal reflection due to causes other than normal reflection and refraction.
  • the conventional light source uses a fluorescent lamp.
  • the transmission wavelength of the color filter of the liquid crystal display element 10 is set narrow to increase the color purity
  • the use of the fluorescent lamp increases the light loss due to the color filter.
  • the brightness of the image decreases.
  • Embodiment 3 since the color purity is improved by improving the monochromaticity of the laser light source, the LED light source and the phosphor, the loss of light is reduced, the decrease in brightness is suppressed, and the power consumption is reduced. Color purity can be increased.
  • the backlight unit 5C configured by laminating a plurality of planar light sources 301, 400a, and 400b in Embodiment 3 includes light guide plates 41 and 42 provided on the upper layer side of the + Z axis direction side, and these light guide plates.
  • the micro optical elements 41d and 42d provided on 41 and 42 are both made of a transparent member. For this reason, the illumination light emitted from the front surface of the light guide plate 31 disposed on the lower layer side on the ⁇ Z-axis direction side is incident on the rear surfaces of the upper light guide plates 41 and 42, but the illumination light is incident on the upper layer. Since the light guide plates 41 and 42 on the side and the fine optical elements 41d and 42d are transmitted, it is possible to suppress a loss of illumination light from the lower layer side and obtain high light use efficiency.
  • a red laser light source having a peak wavelength of 640 nm is used for the light sources 40a and 40b constituting the light source groups 40Ga and 40Gb.
  • the present invention is not limited to this.
  • the color of the illumination light emitted from the front surface of the light guide plate 31 is configured to have a color that is complementary to the emission color of the laser light source.
  • FIG. 16 is a configuration diagram schematically showing a configuration of a liquid crystal display device 104 which is a transmissive display device according to the fourth embodiment of the present invention.
  • the liquid crystal display device 101 according to the first embodiment includes the optical sheet 12, whereas the liquid crystal display device 104 according to the fourth embodiment differs in that the optical sheet 12 is not provided.
  • the same components as those of the liquid crystal display device 101 described in Embodiment 1 are denoted by the same reference numerals, and the description thereof is omitted.
  • the liquid crystal display device 104 includes a transmissive liquid crystal display element 10, an optical sheet 11 that is a first optical sheet, and a backlight unit 5 ⁇ / b> A. , 5A are stacked in the Z-axis direction.
  • the backlight unit 5A of the present embodiment is composed of light source groups 20Ga and 20Gb, a light guide plate 21, and a light diffusion reflection sheet 26. Therefore, the backlight unit 5A of the present embodiment is the same as the backlight unit 5A of the first embodiment.
  • the main function of the optical sheet 12 provided in the liquid crystal display device 101 of the first embodiment is to suppress uneven luminance distribution of illumination light emitted from the backlight unit.
  • an optical sheet is generally provided for the purpose of suppressing uneven luminance distribution.
  • the liquid crystal display device 104 of the fourth embodiment does not include the optical sheet 12. This is because the backlight unit 5A of the present embodiment can emit planar light with excellent uniformity of in-plane spatial luminance distribution as compared with the conventional backlight unit.
  • the planar light having excellent uniformity of spatial luminance distribution can be emitted from the backlight unit 5A for the following reason as described above.
  • the light beams ILa and ILb emitted from the light source groups 20Ga and 20Gb become planar illumination lights BLa and BLb from the back surface 21b of the light guide plate 21 to the back surface of the light guide plate 21 (with the liquid crystal display element 10).
  • the light is emitted toward the light diffusing and reflecting sheet 26 provided on the opposite side (the ⁇ Z-axis direction) side.
  • the illumination lights BLa and BLb are diffused and reflected by the light diffusion reflection sheet 26 to become illumination light directed in the + Z-axis direction, pass through the light guide plate 21 and are emitted from the surface of the light guide plate 21.
  • the illumination lights BLa and BLb traveling in the + Z-axis direction are emitted from the surface of the light guide plate 21, they are further diffused by the refracting action of the micro optical elements 21d,. Therefore, the light beams ILa and ILb emitted from the light source groups 20Ga and 20Gb propagate an optical distance corresponding to at least twice the thickness of the light guide plate before being emitted from the surface of the light guide plate 21. Therefore, it is possible to ensure an optical distance for the light beam to diffuse by its own divergence angle while suppressing the size of the backlight unit 5 ⁇ / b> A before being emitted from the surface of the light guide plate 21.
  • the light beams ILa and ILb become illumination lights BLa and BLb which are planar lights by the optical action of the micro optical elements 21d,.
  • the illumination lights BLa and BLb are diffused and reflected by the light diffusion reflection sheet 26 in the optical path from the surface of the light guide plate 21 until it is emitted. Due to this light diffusion action, the illumination lights BLa and BLb are emitted from the surface of the light guide plate 21 after being diffused and spatially overlapped in the XY plane even in the vicinity of the light incident end of the light guide plate 21 and other positions. .
  • the illumination lights BLa and BLb are emitted from the surface of the light guide plate 21, they are further diffused by the refractive action of the micro optical elements 21d,. Due to these diffusing actions, the in-plane luminance distribution of the illumination lights BLa and BLb emitted from the backlight unit 5A has excellent uniformity.
  • an image without luminance unevenness is provided without the need for the optical sheet 12 provided to improve the uniformity of the in-plane luminance distribution of planar light. Is possible. Therefore, the number of parts can be reduced, and effects such as cost reduction and simplification of the assembly process can be obtained.
  • the structure for obtaining the light diffusing action is provided along the normal direction of the image display surface 10f, that is, the direction perpendicular to the surface of the display surface 10f. .
  • an optical path for efficiently diffusing light in the thickness direction of the backlight unit 5A is efficiently provided using the thickness of the light guide plate 21 and the light reflection optical path.
  • the backlight unit 5A is not enlarged in the in-plane direction of the display surface 10f of the liquid crystal display element 10 (the in-plane direction of the XY plane), and the width of the bezel that is the cabinet portion surrounding the image display portion. It is possible to make the design thinner, and it is possible to suppress uneven brightness distribution of illumination light emitted from the backlight unit 5A.
  • the liquid crystal display device 104 provides a high-quality image with reduced luminance distribution with a simple and small configuration without the need for the optical sheet 12. Is possible.
  • FIG. 17 is a configuration diagram schematically showing the configuration of the liquid crystal display device 105 of the fifth embodiment.
  • the liquid crystal display device 102 of the second embodiment is provided with the optical sheet 12, whereas the liquid crystal display device 105 of the fifth embodiment is different in that the optical sheet 12 is not provided.
  • the same components as those of the liquid crystal display device 102 described in the second embodiment are denoted by the same reference numerals, and the description thereof is omitted.
  • the liquid crystal display device 105 includes a transmissive liquid crystal display element 10, an optical sheet 11 that is a first optical sheet, and a backlight unit 5B. 11 and 5B are stacked and arranged in the Z-axis direction.
  • the backlight unit 5B includes light source groups 32Ga and 32Gb, a light guide plate 31, and a phosphor sheet 38 in which a phosphor 37 that emits green light is applied to a light diffusion reflection sheet 36. That is, the phosphor sheet 38 is composed of the light diffuse reflection sheet 36 and the phosphor 37.
  • the backlight unit 5B of the present embodiment is the same as the backlight unit 5B of the second embodiment.
  • the light guide plate 31 of the present embodiment has the same structure as the light guide plate 31 of the second embodiment described above. Therefore, the light guide plate 31 similarly acts on the light beams ILc and ILd emitted from the light source groups 32Ga and 32Gb. Light beams ILc and ILd emitted from the light source groups 32Ga and 32Gb propagate through the light guide plate 31. At that time, the red light and the blue light are mixed, and the light beams ILc and ILd are mixed light beams.
  • the light beams ILc and ILd are converted into illumination lights BLc and BLd directed in the ⁇ Z axis direction by the micro optical elements 31d,..., 31d formed on the surface of the light guide plate 31 in the + Z axis direction.
  • the illumination lights BLc and BLd are first planar light in which the blue light beam BL and the red light beam RL are mixed.
  • the illumination lights BLc and BLd are emitted toward the phosphor sheet 38 from the surface 31b of the light guide plate 31 on the ⁇ Z axis direction side.
  • Illumination light FL is emitted.
  • the green illumination light FL is second planar light.
  • the excitation light is light used for exciting the phosphor 37.
  • the illumination lights BLc and BLd are diffused and reflected by the surface of the phosphor 37 arranged on the + Z axis direction side of the phosphor sheet 38 or the light diffusion reflection sheet 36 arranged on the ⁇ Z axis direction side of the phosphor sheet 38. Is done.
  • the reflected illumination lights BLc and BLd are mixed light of the blue light beam BL and the red light beam RL that are not used for exciting the phosphor 37, and the first planar light (illumination light BLc and BLd). Is emitted from the phosphor sheet 38 in the + Z-axis direction.
  • the first planar light (illumination light BLc, BLd) composed of the blue light beam BL and the red light beam RL is a second green planar light beam emitted from the phosphor 37 of the phosphor sheet 38 ( Is mixed with the illumination light FL) and becomes white illumination light, which is emitted in the + Z-axis direction.
  • the light beam FL emitted from the phosphor 37 of the phosphor sheet 38 the light beam emitted in the ⁇ Z-axis direction is diffused and reflected by the light diffusion reflection sheet 36 in the + Z-axis direction.
  • the blue and red light beams are emitted from the light guide plate 31 in the ⁇ Z-axis direction and reflected from the surface of the phosphor 37 of the phosphor sheet 38 or the light diffusion reflection sheet 36.
  • the light is diffused and reflected by the surface, and returns to the light guide plate 31 again.
  • the light beam travels back and forth along the optical path provided along the normal direction of the image display surface 10f of the liquid crystal display element 10, and is diffused by the phosphor sheet 38, and thus is emitted from the backlight unit 5B.
  • the in-plane luminance distribution of the illumination light has excellent uniformity.
  • the illumination light FL has an in-plane luminance distribution even when non-uniform blue light is incident on the phosphor 37.
  • the light is emitted from the phosphor 37 as uniform green planar light.
  • the first planar light (illumination light BLc, BLd) composed of blue and red and the green second planar light (illumination light FL) are mixed to produce a white color with a uniform in-plane luminance distribution.
  • the third planar light (illumination light ML) is used to illuminate the liquid crystal display element 10. Therefore, the liquid crystal display device 105 of Embodiment 5 can provide a good image with reduced luminance distribution with a simple and small configuration.
  • the structure for obtaining the light diffusing action is provided along the normal direction of the image display surface 10f, that is, the direction perpendicular to the surface of the display surface 10f. .
  • an optical path for efficiently diffusing light in the thickness direction of the backlight unit 5B is efficiently provided by using the thickness of the light guide plate 31 and the light reflection optical path.
  • the backlight unit 5B does not increase in size in the in-plane direction of the display surface 10f of the liquid crystal display element 10 (in the in-plane direction of the XY plane), and the width of the bezel that is the cabinet portion surrounding the image display portion is increased. It is possible to make the design thinner, and to suppress uneven brightness distribution of illumination light emitted from the backlight unit 5B.
  • the liquid crystal display device 105 provides a high-quality image with reduced luminance distribution with a simple and small configuration without the need for the optical sheet 12. Is possible.
  • the various embodiments according to the present invention have been described above with reference to the drawings.
  • the first to fifth embodiments are useful for a backlight unit (surface light source device) and a liquid crystal display device that generate illumination light with a uniform in-plane luminance distribution, and a liquid crystal with improved reliability by suppressing uneven luminance distribution.
  • a display device can be realized.
  • 10 liquid crystal display element 10f display surface, 5A, 5B, 5C backlight unit, 20, 30, 40a, 40b light source, 21, 31, 41, 42 light guide plate, ILa, ILb, 34, 44 light beam, 21ea, 21eb, 31ea, 31eb, 41ea, 42eb Light incident end face, 21d, 31d, 41d, 42d fine optical element, Pa, Pb light propagation part, BLa, BLb, BLc, BLd, FL, ML, DLa, DLb illumination light, Ra, Rb Optical element part, 36 light diffuse reflection sheet, 37 phosphor, 38 phosphor sheet, 101, 102, 103, 104, 105 liquid crystal display device.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Planar Illumination Modules (AREA)

Abstract

A surface light-source apparatus (5A) is provided with: a plurality of light sources (20Ga, 20Gb) that radiate first light beams (ILa, ILb); a light guiding plate (21) that comprises light entering end faces (21ea, 21eb) from which the first light beams (ILa, ILb) enter, and a front face upon which optical elements (21d) are formed; and a reflection member (26) arranged so as to face the back face (21b) of the light guiding plate (21). The optical elements (21d) make the first light beams (ILa, ILb) entering from the light entering end faces (21ea, 21eb) reflect internally towards the direction of the reflection member (26), to generate surface light (Bla, BLb). The reflection member (26) reflects the surface light radiated from the back face (21b) of the light guiding plate (21) towards the direction of the light guiding plate (21). The light guiding plate (21) lets the surface light entering from the reflection member (26) transmit therethrough, and radiates the light as illumination light.

Description

面光源装置および液晶表示装置Surface light source device and liquid crystal display device
　本発明は、複数の光源から出射された複数の光線を面状の照明光に変換する面光源装置と、この面光源装置をバックライトユニットとして有する液晶表示装置とに関するものである。 The present invention relates to a surface light source device that converts a plurality of light beams emitted from a plurality of light sources into planar illumination light, and a liquid crystal display device that includes the surface light source device as a backlight unit.
　液晶表示装置が備える液晶表示素子は、自ら発光しないため、液晶表示装置を照明する光源（面光源装置）として、液晶表示素子の背面にバックライト装置を備える必要がある。バックライト装置の光源としては、従来は、ガラス管の内壁に蛍光体を塗布し白色の光を得る冷陰極蛍光ランプ（以下、ＣＣＦＬ（Ｃｏｌｄ　Ｃａｔｈｏｄｅ　Ｆｌｕｏｒｅｓｃｅｎｔ）という。）が主流であったが、近年では、発光ダイオード（以下、ＬＥＤ（Ｌｉｇｈｔ　Ｅｍｉｔｔｉｎｇ　Ｄｉｏｄｅ）という。）の性能が飛躍的に向上したのに伴い、ＬＥＤを光源とするバックライト装置に対する需要が急速に高まっている。 Since the liquid crystal display element included in the liquid crystal display device does not emit light by itself, it is necessary to provide a backlight device on the back of the liquid crystal display element as a light source (surface light source device) for illuminating the liquid crystal display device. Conventionally, a cold cathode fluorescent lamp (hereinafter referred to as CCFL (Cold Cathode Fluorescent)), which obtains white light by applying a phosphor on the inner wall of a glass tube, has been the mainstream as a light source of a backlight device. Then, as the performance of light emitting diodes (hereinafter referred to as LEDs (Light Emitting Diodes)) has dramatically improved, the demand for backlight devices using LEDs as light sources is rapidly increasing.
　一般にＬＥＤと呼ばれる素子には、ＬＥＤの直接発光により赤色、緑色、あるいは青色等の単色光を得る単色ＬＥＤや、ＬＥＤの直接発光による単色の青色光でそのパッケージ内に備えた黄色蛍光体を励起して白色光を得る白色ＬＥＤ等がある。直接発光のＬＥＤから出射される光は単色性に優れるため色純度が高く、これをバックライト装置の光源に採用することにより色再現領域を拡大することができ、鮮やかな画像を提供する液晶表示装置を提供することができる。白色ＬＥＤは発光効率が高く、これをバックライト装置の光源に採用することにより低消費電力化が期待できる。また、ＬＥＤは電流制御によりその輝度を０％から１００％の範囲で制御することが可能であるため、画像の輝度に合わせてＬＥＤの光量を変化させることにより、消費電力を大幅に削減し、また動的な画像のコントラストを向上させることが可能となる。 In an element generally called an LED, a monochromatic LED that obtains monochromatic light such as red, green, or blue by direct light emission of the LED, or a yellow phosphor provided in the package by monochromatic blue light by direct light emission of the LED is excited. Thus, there are white LEDs that obtain white light. The light emitted from the direct light emitting LED has high monochromaticity and high color purity. By adopting this as the light source of the backlight device, the color reproduction area can be expanded and a liquid crystal display providing a vivid image An apparatus can be provided. White LEDs have high luminous efficiency, and low power consumption can be expected by adopting them as light sources for backlight devices. In addition, since the brightness of the LED can be controlled in the range of 0% to 100% by current control, the power consumption is greatly reduced by changing the light quantity of the LED according to the brightness of the image, In addition, the contrast of dynamic images can be improved.
　また、近年ではテレビやモニター等の液晶表示装置において薄型化が望まれ、バックライト装置には、従来の光源を液晶表示素子の背面に配列し面状光源を生成するいわゆる直下方式に対し、複数の光源を導光板の端部近傍に配置し、この導光板を利用して、複数の光源から発せられた線状光を面状光に変換する、いわゆるサイドライト方式あるいはエッジライト方式が広く採用されてきている。 In recent years, it has been desired to reduce the thickness of liquid crystal display devices such as televisions and monitors. The backlight device includes a plurality of conventional light sources arranged on the back surface of a liquid crystal display element to generate a planar light source. The light source is placed near the edge of the light guide plate, and using this light guide plate, linear light emitted from multiple light sources is converted into planar light, so-called side light method or edge light method is widely adopted Has been.
　特に、大型の液晶表示装置のバックライト装置にサイドライト方式あるいはエッジライト方式を適用する場合、単位発光面積当たりの発光出力が大きく、必要輝度に対する光源数を少なくすることが可能なＬＥＤを採用することは有効である。 In particular, when a side light method or an edge light method is applied to a backlight device of a large liquid crystal display device, an LED that has a large light emission output per unit light emitting area and can reduce the number of light sources with respect to necessary luminance is adopted. It is effective.
　しかしながら、一方で、ＬＥＤのような指向性を有する光を発する点光源を、サイドライト方式あるいはエッジライト方式のバックライト装置に組み込まれる光源として採用した場合、当該光源近傍の輝度が著しく高くなり、その結果、導光板の光入射端の付近において輝度分布むらが生じるといった課題がある。 However, on the other hand, when a point light source that emits directional light such as an LED is used as a light source incorporated in a sidelight type or edge light type backlight device, the luminance in the vicinity of the light source is significantly increased, As a result, there is a problem that uneven luminance distribution occurs in the vicinity of the light incident end of the light guide plate.
　このような課題は、たとえば、多数の点光源を狭い間隔で一列に配置して線状光源に近づける様な構成を採用することにより改善することが可能であるが、均一性の高い面内輝度分布を求められる液晶表示装置のバックライト装置では非常に多数の点光源が必要となるため、消費電力、組立性およびコストの面において問題がある。 Such a problem can be improved, for example, by adopting a configuration in which a large number of point light sources are arranged in a line at a narrow interval so as to be close to a linear light source. Since the backlight device of the liquid crystal display device that requires distribution requires a large number of point light sources, there are problems in terms of power consumption, ease of assembly, and cost.
　そこで、従来では、できる限り少ない光源数で面内輝度分布の均一な面光源を得るための技術が報告されている。たとえば、特開２００７－２２０４４７号公報（特許文献１）に開示されているサイドライト型バックライト装置では、導光板の光入射面に平行な貫通孔が当該導光板に形成されている。この貫通孔により入射光を効果的に拡散させる光拡散構造が実現されている。この光拡散構造は、点光源の各々から出射される光を点光源の配列方向に拡散させる。点光源から出射された光は、導光板の側面から導光板内部に入射し屈折して導光板の表面に導光される。これにより、点光源の近傍では当該点光源の配列方向に不均一であった光は、光拡散構造で点光源の配列方向に均一な光に変換され、その後、導光板の光屈折構造に入射するため、導光板表面から出射される光は、輝度むらが抑えられた面内輝度分布が均一な面状光となる。 Therefore, conventionally, a technique for obtaining a surface light source having a uniform in-plane luminance distribution with the smallest possible number of light sources has been reported. For example, in the sidelight type backlight device disclosed in Japanese Patent Application Laid-Open No. 2007-220447 (Patent Document 1), a through hole parallel to the light incident surface of the light guide plate is formed in the light guide plate. A light diffusing structure that effectively diffuses incident light is realized by this through hole. This light diffusion structure diffuses the light emitted from each of the point light sources in the arrangement direction of the point light sources. The light emitted from the point light source enters the light guide plate from the side surface of the light guide plate, refracts, and is guided to the surface of the light guide plate. As a result, light that is not uniform in the arrangement direction of the point light source in the vicinity of the point light source is converted into uniform light in the arrangement direction of the point light source by the light diffusion structure, and then incident on the light refraction structure of the light guide plate Therefore, the light emitted from the surface of the light guide plate becomes planar light with a uniform in-plane luminance distribution in which luminance unevenness is suppressed.
特開２００７－２２０４４７号公報JP 2007-220447 A
　しかしながら、上記特許文献１の技術では、光拡散構造が導光板と同一平面に設けられており、光を十分に均一化するために必要な光学距離を設けると、導光板の周辺部のサイズが大きくなる。このため、画像表示部分を囲むキャビネット部分であるベゼルの幅が大きくなり、液晶表示装置が大型化するという問題がある。 However, in the technique of Patent Document 1, the light diffusion structure is provided on the same plane as the light guide plate, and if the optical distance necessary for sufficiently uniforming the light is provided, the size of the peripheral portion of the light guide plate is reduced. growing. For this reason, there is a problem that the width of the bezel which is a cabinet portion surrounding the image display portion is increased, and the liquid crystal display device is increased in size.
　本発明は、上記課題に鑑みて成されたものであって、簡易で小型な構成により面内輝度分布のむらを抑えた面光源装置および液晶表示装置を提供することを目的とする。 The present invention has been made in view of the above problems, and an object thereof is to provide a surface light source device and a liquid crystal display device in which unevenness of in-plane luminance distribution is suppressed with a simple and small configuration.
　この発明の第１の態様による面光源装置は、複数の第１の光線をそれぞれ出射する複数の第１の光源と、前記複数の第１の光線が入射する光入射端面を有するとともに複数の第１の光学素子が形成された前面を有する第１の導光板と、前記第１の導光板の裏面と対向するように配置される反射部材とを備え、前記複数の第１の光学素子は、前記光入射端面に入射した当該複数の第１の光線を前記反射部材の方向に内面反射させて面状光を生成し、前記反射部材は、前記第１の導光板の前記裏面から放射された当該面状光を前記第１の導光板の方向に反射させ、前記第１の導光板は、前記反射部材から入射した当該面状光を透過させて前記前面から第１の照明光として放射するものである。 A surface light source device according to a first aspect of the present invention includes a plurality of first light sources that respectively emit a plurality of first light beams, a light incident end surface on which the plurality of first light beams are incident, and a plurality of first light sources. A first light guide plate having a front surface on which one optical element is formed, and a reflective member disposed to face the back surface of the first light guide plate, wherein the plurality of first optical elements are: The plurality of first light beams incident on the light incident end surface are internally reflected in the direction of the reflecting member to generate planar light, and the reflecting member is emitted from the back surface of the first light guide plate. The planar light is reflected in the direction of the first light guide plate, and the first light guide plate transmits the planar light incident from the reflection member and emits the first illumination light from the front surface. Is.
　この発明の第２の態様による液晶表示装置は、前記第１の態様による面光源装置と、前記面光源装置から放射された面状光の強度を空間的に変調して画像光を生成する液晶表示素子とを備える。 A liquid crystal display device according to a second aspect of the present invention includes a surface light source device according to the first aspect and a liquid crystal that generates image light by spatially modulating the intensity of the planar light emitted from the surface light source device. A display element.
　この発明によれば、小型な構成で、第１の光源から発せられた光の指向性に起因する輝度分布むらを抑制した面光源装置および液晶表示装置を提供することができる。 According to the present invention, it is possible to provide a surface light source device and a liquid crystal display device that have a small configuration and suppress uneven luminance distribution due to directivity of light emitted from the first light source.
本発明に係る実施の形態１の液晶表示装置の構成を模式的に示す図である。It is a figure which shows typically the structure of the liquid crystal display device of Embodiment 1 which concerns on this invention. 本発明に係る実施の形態１の液晶表示装置の面状光源の概略図である。It is the schematic of the planar light source of the liquid crystal display device of Embodiment 1 which concerns on this invention. 実施の形態１の導光板の前面に形成されている微細光学素子の概略断面図である。2 is a schematic cross-sectional view of a micro optical element formed on the front surface of the light guide plate of Embodiment 1. FIG. 実施の形態１の光学シートの構造の一例を概略的に示す斜視図である。3 is a perspective view schematically showing an example of the structure of the optical sheet of Embodiment 1. FIG. 本発明に係る実施の形態２の液晶表示装置の構成を模式的に示す図である。It is a figure which shows typically the structure of the liquid crystal display device of Embodiment 2 which concerns on this invention. 本発明に係る実施の形態２の液晶表示装置の面状光源の概略図である。It is the schematic of the planar light source of the liquid crystal display device of Embodiment 2 which concerns on this invention. 本発明に係る実施の形態３の液晶表示装置の構成を模式的に示す図である。It is a figure which shows typically the structure of the liquid crystal display device of Embodiment 3 which concerns on this invention. 実施の形態３の液晶表示装置の面状光源の概略構成を示す図である。6 is a diagram illustrating a schematic configuration of a planar light source of a liquid crystal display device according to Embodiment 3. FIG. 実施の形態３の液晶表示装置の他の面状光源の概略構成を示す図である。It is a figure which shows schematic structure of the other planar light source of the liquid crystal display device of Embodiment 3. 実施の形態３の液晶表示装置のさらに他の面状光源の概略構成を示す図である。It is a figure which shows schematic structure of the other planar light source of the liquid crystal display device of Embodiment 3. FIG. 本発明に係る実施の形態３の液晶表示装置の隣り合う２つの光源から出射された光線が導光板内を伝播して線状光源となることを説明する概念図である。It is a conceptual diagram explaining that the light ray radiate | emitted from two adjacent light sources of the liquid crystal display device of Embodiment 3 which concerns on this invention propagates the inside of a light-guide plate, and becomes a linear light source. 本発明に係る実施の形態３の液晶表示装置のバックライトユニットから出射される照明光のＸ軸方向における１次元輝度分布のシミュレーション結果を示す特性図である。It is a characteristic view which shows the simulation result of the one-dimensional luminance distribution in the X-axis direction of the illumination light radiate | emitted from the backlight unit of the liquid crystal display device of Embodiment 3 which concerns on this invention. 本発明に係る実施の形態３の液晶表示装置のバックライトユニットから出射される照明光の面内輝度分布の計測結果を示した特性図である。It is the characteristic view which showed the measurement result of the in-plane luminance distribution of the illumination light radiate | emitted from the backlight unit of the liquid crystal display device of Embodiment 3 which concerns on this invention. 本発明に係る実施の形態３の液晶表示装置におけるレーザ光線の光路を概念的に示した図である。It is the figure which showed notionally the optical path of the laser beam in the liquid crystal display device of Embodiment 3 which concerns on this invention. 本発明に係る実施の形態３の液晶表示装置の光伝播部を伝播したレーザ光線の１次元輝度分布を示す特性図である。It is a characteristic view which shows the one-dimensional luminance distribution of the laser beam which propagated the light propagation part of the liquid crystal display device of Embodiment 3 which concerns on this invention. 本発明に係る実施の形態４の液晶表示装置の構成を模式的に示す図である。It is a figure which shows typically the structure of the liquid crystal display device of Embodiment 4 which concerns on this invention. 本発明に係る実施の形態５の液晶表示装置の構成を模式的に示す図である。It is a figure which shows typically the structure of the liquid crystal display device of Embodiment 5 which concerns on this invention.
　以下に、本発明に係る種々の実施の形態を図面に基づいて詳細に説明する。なお、以下の実施の形態により本発明が限定されるものではない。 Hereinafter, various embodiments according to the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by the following embodiment.
実施の形態１．
　図１は、本発明に係る実施の形態１の透過型表示装置である液晶表示装置１０１の構成を模式的に示す構成図である。また、図２は、液晶表示装置１０１のバックライトユニット５Ａを構成する面状光源２００を概略的に示す図である。図の説明を容易にするために液晶光学素子１０の短辺方向をＹ軸方向とし、その長辺方向をＸ軸方向とし、Ｘ－Ｙ平面（表示面）に垂直な方向をＺ軸方向とし、液晶表示素子１０の表示面１０ｆ側の方向を＋Ｚ軸方向とし、その反対側の方向を－Ｚ軸方向とする。また、液晶表示装置１０１の上方向を＋Ｙ軸方向とし、その反対側の方向を－Ｙ軸方向とする。液晶表示装置１０１の表示面１０ｆに向かって右方向を＋Ｘ軸方向とし、その左方向を－Ｘ軸方向とする。 Embodiment 1 FIG.
FIG. 1 is a configuration diagram schematically showing a configuration of a liquid crystal display device 101 which is a transmissive display device according to the first embodiment of the present invention. FIG. 2 is a diagram schematically showing a planar light source 200 constituting the backlight unit 5 </ b> A of the liquid crystal display device 101. For ease of illustration, the short side direction of the liquid crystal optical element 10 is defined as the Y-axis direction, the long side direction is defined as the X-axis direction, and the direction perpendicular to the XY plane (display surface) is defined as the Z-axis direction. The direction on the display surface 10f side of the liquid crystal display element 10 is the + Z-axis direction, and the opposite direction is the −Z-axis direction. Further, the upward direction of the liquid crystal display device 101 is defined as the + Y axis direction, and the opposite direction is defined as the −Y axis direction. The right direction toward the display surface 10f of the liquid crystal display device 101 is the + X axis direction, and the left direction is the −X axis direction.
　図１に示されるように、液晶表示装置１０１は、透過型の液晶表示素子１０と、第１の光学シートである光学シート１１と、第２の光学シートである光学シート１２と、面光源装置であるバックライトユニット５Ａとを備えており、これらの構成要素１０，１１，１２，５Ａは、Ｚ軸方向に積層して配列されている。液晶表示素子１０は、Ｚ軸に直交するＸ軸及びＹ軸を含むＸ－Ｙ平面と平行な表示面１０ｆを有する。尚、Ｘ軸及びＹ軸は互いに直交している。 As shown in FIG. 1, a liquid crystal display device 101 includes a transmissive liquid crystal display element 10, an optical sheet 11 that is a first optical sheet, an optical sheet 12 that is a second optical sheet, and a surface light source device. The constituent elements 10, 11, 12, 5A are stacked and arranged in the Z-axis direction. The liquid crystal display element 10 has a display surface 10f parallel to an XY plane including an X axis and a Y axis perpendicular to the Z axis. Note that the X axis and the Y axis are orthogonal to each other.
　液晶表示装置１０１は、さらに、液晶表示素子１０を駆動する図示しない液晶表示素子駆動部と、バックライトユニット５Ａに含まれる光源群２０Ｇａ，２０Ｇｂを駆動する図示しない光源駆動部とを有している。液晶表示素子駆動部と光源駆動部の動作は、図示しない制御部によって制御される。制御部は、図示しない信号源から供給された映像信号に画像処理を施して制御信号を生成し、これら制御信号を液晶表示素子駆動部及び光源駆動部に供給する。光源駆動部は、制御部からの制御信号に応じて光源群２０Ｇａ，２０Ｇｂを駆動して光源群２０Ｇａ，２０Ｇｂから光を出射させる。光源群２０Ｇａは、図２に示されるようにＹ軸方向に沿って一列に配列される複数の光源２０，…，２０からなり、光源群２０Ｇｂも、Ｙ軸方向に沿って一列に配列される複数の光源２０，…，２０からなる。 The liquid crystal display device 101 further includes a liquid crystal display element driving unit (not shown) that drives the liquid crystal display element 10 and a light source driving unit (not shown) that drives the light source groups 20Ga and 20Gb included in the backlight unit 5A. . The operations of the liquid crystal display element driving unit and the light source driving unit are controlled by a control unit (not shown). The control unit performs image processing on a video signal supplied from a signal source (not shown) to generate a control signal, and supplies the control signal to the liquid crystal display element driving unit and the light source driving unit. The light source driving unit drives the light source groups 20Ga and 20Gb according to a control signal from the control unit to emit light from the light source groups 20Ga and 20Gb. The light source group 20Ga includes a plurality of light sources 20,..., 20 arranged in a line along the Y-axis direction as shown in FIG. 2, and the light source group 20Gb is also arranged in a line along the Y-axis direction. It consists of a plurality of light sources 20,.
　バックライトユニット５Ａは、光源群２０Ｇａ，２０Ｇｂと導光板２１と光拡散反射シート２６とから構成されている。光源群２０Ｇａ，２０Ｇｂは、導光板２１のＸ軸方向の両端面に設けられた光入射端面２１ｅａ，２１ｅｂにそれぞれ対向して配置されている。光源群２０Ｇａ，２０Ｇｂから出射された光線ＩＬａ，ＩＬｂは、導光板２１の両端面の光入射端面２１ｅａ，２１ｅｂから中心方向に向かって入射する。光拡散反射シート２６は、導光板２１の液晶表示素子１０とは反対側の面２１ｂ（－Ｚ軸方向側の面）と対向し、導光板２１と平行となるように配置されている。光源群２０Ｇａ，２０Ｇｂは、白色の光を出射する複数個のＬＥＤなどの光源２０，…，２０が一定の間隔でＹ軸方向に配列する構成を有している。導光板２１は、液晶表示素子１０の表示面１０ｆに対して平行に配置され、導光板２１の液晶表示素子１０側の面である表面に微細光学素子２１ｄ，…，２１ｄを有する。 The backlight unit 5A is composed of light source groups 20Ga and 20Gb, a light guide plate 21, and a light diffusion reflection sheet 26. The light source groups 20Ga and 20Gb are arranged to face the light incident end faces 21ea and 21eb provided on both end faces in the X-axis direction of the light guide plate 21, respectively. The light beams ILa and ILb emitted from the light source groups 20Ga and 20Gb are incident toward the central direction from the light incident end surfaces 21ea and 21eb on the both end surfaces of the light guide plate 21. The light diffusion reflection sheet 26 is disposed so as to face the surface 21 b (surface on the −Z axis direction side) opposite to the liquid crystal display element 10 of the light guide plate 21 and to be parallel to the light guide plate 21. The light source groups 20Ga and 20Gb have a configuration in which light sources 20,..., 20 such as a plurality of LEDs that emit white light are arranged in the Y-axis direction at regular intervals. The light guide plate 21 is arranged in parallel to the display surface 10f of the liquid crystal display element 10, and has fine optical elements 21d, ..., 21d on the surface of the light guide plate 21 on the liquid crystal display element 10 side.
　なお、光の拡散とは、媒質に入射した光が媒質中の分子に当たることによりその進行方向にずれが生じ、元の進行方向やあるいは正反射の方向よりも広い範囲の方向に進む現象をいう。また、自らの発散角により広がる現象も光の拡散と呼ぶ。 Light diffusion refers to a phenomenon in which light traveling on a medium strikes molecules in the medium, causing a shift in the traveling direction, and traveling in a wider range than the original traveling direction or specular reflection direction. . In addition, the phenomenon spreading by its own divergence angle is also called light diffusion.
　導光板２１は、光源群２０Ｇａ，２０Ｇｂから出射される白色の光線ＩＬａ，ＩＬｂを導光板２１の＋Ｚ軸方向の面に形成された微細光学素子２１ｄ，…，２１ｄの屈折作用により－Ｚ軸方向に向かう面状の照明光ＢＬａ，ＢＬｂに変換する。照明光ＢＬａ，ＢＬｂは、導光板２１の－Ｚ軸方向側に配置される光拡散反射シート２６に向けて第１の面状の光として導光板２１から出射する。微細光学素子２１ｄ，…，２１ｄは、光線ＩＬａ，ＩＬｂの進行方向を屈折により－Ｚ軸方向に変換して照明光ＢＬａ，ＢＬｂを生成する光学素子である。 The light guide plate 21 emits white light beams ILa and ILb emitted from the light source groups 20Ga and 20Gb to the −Z axis direction by the refractive action of the micro optical elements 21d,..., 21d formed on the surface of the light guide plate 21 in the + Z axis direction. Are converted into planar illumination lights BLa and BLb. The illumination lights BLa and BLb are emitted from the light guide plate 21 as the first planar light toward the light diffusion reflection sheet 26 disposed on the −Z axis direction side of the light guide plate 21. The fine optical elements 21d,..., 21d are optical elements that generate illumination lights BLa and BLb by converting the traveling directions of the light beams ILa and ILb into the −Z-axis direction by refraction.
　光拡散反射シート２６に向けて出射された照明光ＢＬａ，ＢＬｂは、光拡散反射シート２６で拡散し、＋Ｚ軸方向に向けて反射する。光拡散反射シート２６としては、たとえば、ポリエチレンテレフタラートなどの樹脂を基材とした光拡散反射シートや、微細な凹凸形状を有する基板の表面に金属を蒸着させた光拡散反射シートを使用することができる。 The illumination lights BLa and BLb emitted toward the light diffusive reflection sheet 26 are diffused by the light diffusive reflection sheet 26 and reflected toward the + Z-axis direction. As the light diffusing and reflecting sheet 26, for example, a light diffusing and reflecting sheet based on a resin such as polyethylene terephthalate or a light diffusing and reflecting sheet obtained by depositing metal on the surface of a substrate having a fine uneven shape is used. Can do.
　白色の照明光は、導光板２１、光学シート１２および光学シート１１を透過してバックライトユニット５Ａから液晶表示素子１０の背面１０ｂに向けて出射される。ここで、光学シート１１は、バックライトユニット５Ａから出射した照明光ＢＬａ，ＢＬｂの進行方向を、液晶表示装置１０１の画面に対する法線方向に向ける作用を有するものである。また光学シート１２は、細かな照明むらなどの光学的影響を抑制するものである。 White illumination light passes through the light guide plate 21, the optical sheet 12, and the optical sheet 11, and is emitted from the backlight unit 5A toward the back surface 10b of the liquid crystal display element 10. Here, the optical sheet 11 has an action of directing the traveling direction of the illumination lights BLa and BLb emitted from the backlight unit 5A in the normal direction to the screen of the liquid crystal display device 101. The optical sheet 12 suppresses optical influences such as fine illumination unevenness.
　液晶表示素子１０は、Ｚ軸方向に直交するＸ－Ｙ平面に平行な液晶層（図示せず）を有する。液晶表示素子１０の表示面１０ｆは矩形状であり、図１に示すＸ軸方向及びＹ軸方向は、それぞれ、この表示面１０ｆの互いに直交する２辺に沿った方向である。液晶表示素子駆動部は、制御部から供給された制御信号に応じて液晶層の光透過率を画素単位または副画素単位で変化させることができる。各画素は、さらに３つまたは４つの副画素から構成されており、副画素の各々は、赤色、緑色もしくは青色の光線のみ、またはこれらの色に、たとえば黄色を加えた４色のうちのいずれかの色の光線のみを透過させるカラーフィルタを備えることができる。各副画素の透過率を制御することによりカラー画像を生成することができる。これにより、液晶表示素子１０は、バックライトユニット５Ａから入射した照明光ＢＬａ，ＢＬｂの強度を空間的に変調して画像光を生成し、この画像光を表示面１０ｆから出射することができる。 The liquid crystal display element 10 has a liquid crystal layer (not shown) parallel to the XY plane orthogonal to the Z-axis direction. The display surface 10f of the liquid crystal display element 10 has a rectangular shape, and the X-axis direction and the Y-axis direction shown in FIG. 1 are directions along two mutually orthogonal sides of the display surface 10f. The liquid crystal display element driving unit can change the light transmittance of the liquid crystal layer in units of pixels or sub-pixels according to a control signal supplied from the control unit. Each pixel is further composed of three or four sub-pixels, and each of the sub-pixels is either red, green or blue light only, or any of these colors, for example, four colors including yellow. It is possible to provide a color filter that transmits only a certain color ray. A color image can be generated by controlling the transmittance of each sub-pixel. Thereby, the liquid crystal display element 10 can generate image light by spatially modulating the intensity of the illumination lights BLa and BLb incident from the backlight unit 5A, and can emit the image light from the display surface 10f.
　導光板２１は、透明部材で形成された、たとえば厚み４ｍｍの板状部材である。図１に示すように、導光板２１の液晶表示素子１０側の面となる表面（前面）には半球状の凸形状（以後、凸レンズ形状と呼ぶ。）の微細光学素子２１ｄ，…，２１ｄが形成されている。この微細光学素子２１ｄ，…，２１ｄは、導光板２１内を伝播する光線ＩＬａ，ＩＬｂを、液晶表示素子１０とは反対側の面となる裏面２１ｂから－Ｚ軸方向に向けて出射される照明光ＢＬａ，ＢＬｂに変換する。 The light guide plate 21 is a plate-like member formed of a transparent member, for example, having a thickness of 4 mm. As shown in FIG. 1, microscopic optical elements 21 d,..., 21 d having a hemispherical convex shape (hereinafter referred to as a convex lens shape) are formed on the surface (front surface) of the light guide plate 21 on the liquid crystal display element 10 side. Is formed. The fine optical elements 21d,..., 21d emit light rays ILa and ILb propagating in the light guide plate 21 from the back surface 21b on the opposite side to the liquid crystal display element 10 in the −Z-axis direction. The light is converted into BLa and BLb.
　導光板２１の光入射端面２１ｅａ，２１ｅｂから入射した光線ＩＬａ，ＩＬｂは、導光板２１と空気層との界面における全反射により導光板２１内を、反射を繰り返しながらＸ軸方向に進行する。光線ＩＬａ，ＩＬｂのうち、導光板２１の裏面２１ｂと空気層との界面における全反射条件を満たさなくなる光線が存在する。その光線は、導光板２１の裏面２１ｂから光拡散反射シート２６に向かって出射される。 The light beams ILa and ILb incident from the light incident end faces 21ea and 21eb of the light guide plate 21 travel in the X-axis direction while being repeatedly reflected in the light guide plate 21 by total reflection at the interface between the light guide plate 21 and the air layer. Among the light beams ILa and ILb, there are light beams that do not satisfy the total reflection condition at the interface between the back surface 21b of the light guide plate 21 and the air layer. The light beam is emitted from the back surface 21 b of the light guide plate 21 toward the light diffusion reflection sheet 26.
　導光板２１の表面に設けられた微細光学素子２１ｄ，…，２１ｄは、Ｘ－Ｙ平面内に形成され、微細光学素子２１ｄ，…，２１ｄの配置密度（すなわち単位面積当たりの数やその大きさなど）が空間的に変化する。これにより、導光板２１から出射する照明光ＢＬａ，ＢＬｂの面内輝度分布を制御することが可能となる。本実施の形態においては、図２に示すように、光線ＩＬａ，ＩＬｂの進行方向（図２中Ｘ軸方向）において導光板２１の光入射端面２１ｅａ，２１ｅｂから導光板２１の中央部に向かうにつれて微細光学素子２１ｄ，…，２１ｄの配置密度が変化する構造が採用されている。 The fine optical elements 21d,..., 21d provided on the surface of the light guide plate 21 are formed in the XY plane, and the arrangement density (that is, the number per unit area and the size thereof) of the fine optical elements 21d,. Etc.) vary spatially. As a result, the in-plane luminance distribution of the illumination lights BLa and BLb emitted from the light guide plate 21 can be controlled. In the present embodiment, as shown in FIG. 2, as the light beams ILa and ILb travel in the traveling direction (X-axis direction in FIG. 2) from the light incident end faces 21 ea and 21 eb of the light guide plate 21 toward the center of the light guide plate 21. A structure in which the arrangement density of the micro optical elements 21d,.
　なお、面内輝度分布とは、任意の平面において、２次元で表される位置に対する輝度の高低を示す分布である。このため、バックライトユニット５Ａの面内輝度分布とは、２次元（Ｘ－Ｙ平面）で表される導光板２１の表面（液晶表示素子１０と対向する側の面）上の位置に関する照明光ＢＬａ，ＢＬｂの輝度の高低を示す分布である。なお、照明光ＢＬａ，ＢＬｂは、導光板２１の表面から出射して液晶表示素子１０の背面１０ｂを照明する。 The in-plane luminance distribution is a distribution indicating the level of luminance with respect to a position expressed in two dimensions on an arbitrary plane. For this reason, the in-plane luminance distribution of the backlight unit 5A is the illumination light related to the position on the surface of the light guide plate 21 (surface facing the liquid crystal display element 10) expressed in two dimensions (XY plane). This is a distribution indicating the level of brightness of BLa and BLb. The illumination lights BLa and BLb are emitted from the surface of the light guide plate 21 to illuminate the back surface 10b of the liquid crystal display element 10.
　より詳しく説明すると、微細光学素子２１ｄ，…，２１ｄの配置密度は、導光板２１における光入射端面２１ｅａ，２１ｅｂの近傍からＸ軸方向の中心位置の近傍に向かって疎から密へと連続的に変化する構成をとる。 More specifically, the arrangement density of the micro optical elements 21d,..., 21d is continuously from sparse to dense from the vicinity of the light incident end faces 21ea and 21eb in the light guide plate 21 toward the vicinity of the center position in the X-axis direction. Take a changing configuration.
　微細光学素子２１ｄの形状としては、たとえば、図３に示されるように、その表面形状は、曲率が約０．１５ｍｍ、最大高さＨｍａｘが約０．００５ｍｍの凸レンズ形状を採用できる。微細光学素子２１ｄの屈折率は約１．４９にすればよい。なお、導光板２１や微細光学素子２１ｄの材質はアクリル樹脂とすることができるが、この材質に限定されるものではない。光透過率が良く、成形加工性に優れた材質であれば、アクリル樹脂に代えてポリカーボネート樹脂などの他の樹脂材料、あるいはガラス材料を使用してもよい。 As the shape of the micro optical element 21d, for example, as shown in FIG. 3, a convex lens shape having a curvature of about 0.15 mm and a maximum height Hmax of about 0.005 mm can be adopted. The refractive index of the micro optical element 21d may be about 1.49. The material of the light guide plate 21 and the fine optical element 21d can be acrylic resin, but is not limited to this material. As long as the material has good light transmittance and excellent moldability, other resin materials such as polycarbonate resin or glass material may be used instead of acrylic resin.
　また、本実施の形態においては、微細光学素子２１ｄを凸レンズ形状としたが、本発明はこれに限るものではない。導光板２１内をＸ軸方向に進行するＬＥＤの光を、Ｚ軸方向に屈折させて光拡散反射シート２６に向かって出射する構造を有していれば、他の形状を採用してもよく、たとえば、プリズム形状や、サンドブラスト等によるランダムな凹凸パターンから成る微細光学素子を採用してもよい。 In the present embodiment, the fine optical element 21d has a convex lens shape, but the present invention is not limited to this. Other shapes may be adopted as long as the LED light that travels in the light guide plate 21 in the X-axis direction is refracted in the Z-axis direction and emitted toward the light diffusion reflection sheet 26. For example, you may employ | adopt the fine optical element which consists of a random uneven | corrugated pattern by prism shape, sandblasting, etc., for example.
　ただし、凸レンズ形状は、透明な構造で光を屈折することが可能で、プリズム等の構造に比べて簡易な形状であるため製作が容易であるという利点を有する。また、導光板２１が大型化した場合でも、印刷による製作が可能であるため、導光板２１の大型化に容易に対応することができる。また、サンドブラスト等によるランダムな凹凸形状でもレーザ光をＺ軸方向に屈折させることはできるが、凸レンズ形状の場合は、凸形状の設計が容易に可能であるため、均一な輝度分布を実現する面状光源２００の設計が容易であるという利点がある。 However, the convex lens shape has an advantage that it can be refracted with a transparent structure and is easy to manufacture because it is a simpler shape than the structure of a prism or the like. Further, even when the light guide plate 21 is enlarged, it can be manufactured by printing, so that it is possible to easily cope with the enlargement of the light guide plate 21. In addition, the laser beam can be refracted in the Z-axis direction even with a random uneven shape such as sandblasting. However, in the case of a convex lens shape, the convex shape can be easily designed, and thus a surface that achieves a uniform luminance distribution. There is an advantage that the design of the light source 200 is easy.
　光源群２０Ｇａ，２０Ｇｂは、４２０ｎｍから７００ｎｍまでの非常に広い波長帯域を有する白色光を出射するＬＥＤなどの光源２０，…，２０からなる。これら光源群２０Ｇａ，２０Ｇｂが出射する白色光から、液晶表示素子１０の備えるカラーフィルタによって赤色、緑色および青色の３つの色の光を切り出し、それら３色の光の混色比を調整することにより色表示が行われる。なお、たとえば、赤色、緑色及び青色に黄色を加えた４色のカラーフィルタを採用する場合は、４つの色の光を切り出すことができ、それら４色の光の混色比を調整することにより色表示が行われる。 The light source group 20Ga, 20Gb includes light sources 20,..., 20 such as LEDs that emit white light having a very wide wavelength band from 420 nm to 700 nm. From the white light emitted by these light source groups 20Ga and 20Gb, the color filter of the liquid crystal display element 10 cuts out the light of three colors of red, green and blue, and adjusts the color mixture ratio of the three colors of light. Display is performed. For example, when four color filters in which yellow is added to red, green, and blue, light of four colors can be cut out, and color can be adjusted by adjusting the color mixture ratio of the four colors of light. Display is performed.
　また、光源群２０Ｇａ，２０Ｇｂから出射される光は、指向性を有しており、光源群２０Ｇａ，２０Ｇｂの発光面の法線方向を中心とし、その半値全角が１２０度の略ランバート分布の角度強度分布をもつ。ランバート分布とは、角度中心における強度を最大として、角度が大きくなるにつれ余弦関数で強度が減少する分布である。従来のＣＣＦＬ光源を採用したサイドライト方式あるいはエッジライト方式のバックライトユニットでは、ＣＣＦＬが線状光源であるため、導光板における光源配置方向に特に輝度むらが発生することは無かった。しかしながら、指向性を有する光を発する複数の点光源を１列に配置した光源群を採用する場合には、導光板の光入射端面近傍において点光源の出射光の光量差に起因する輝度分布むらが生じてしまう。 In addition, the light emitted from the light source groups 20Ga and 20Gb has directivity, and is an angle of a substantially Lambertian distribution with the full width at half maximum being 120 degrees centered on the normal direction of the light emitting surface of the light source groups 20Ga and 20Gb. Has an intensity distribution. The Lambert distribution is a distribution in which the intensity at the angle center is maximized and the intensity decreases with a cosine function as the angle increases. In a sidelight type or edge light type backlight unit employing a conventional CCFL light source, since the CCFL is a linear light source, there was no luminance unevenness particularly in the light source arrangement direction in the light guide plate. However, when a light source group in which a plurality of point light sources that emit light having directivity are arranged in a line is used, uneven luminance distribution due to the difference in the amount of light emitted from the point light source in the vicinity of the light incident end face of the light guide plate. Will occur.
　本実施の形態によると、光源群２０Ｇａ，２０Ｇｂからそれぞれ出射した光線ＩＬａ，ＩＬｂは、導光板２１の内面で全反射しながらＸ軸方向に進行する。それらの光線ＩＬａ，ＩＬｂのうち導光板２１の表面に設けられた微細光学素子２１ｄで内面全反射した光が照明光ＢＬａ，ＢＬｂとなる。照明光ＢＬａ，ＢＬｂは、導光板２１の裏面２１ｂから光拡散反射シート２６に向かって－Ｚ軸方向に出射する。その後、照明光ＢＬａ，ＢＬｂは、光拡散反射シート２６で拡散して反射し、＋Ｚ軸方向に向かう照明光ＢＬａ，ＢＬｂとなり、導光板２１を透過して導光板２１表面から出射する。＋Ｚ軸方向に進行する照明光ＢＬａ，ＢＬｂは、導光板２１の表面から出射する際、微細光学素子２１ｄの屈折作用によりさらに拡散する。 According to the present embodiment, the light beams ILa and ILb respectively emitted from the light source groups 20Ga and 20Gb travel in the X-axis direction while being totally reflected by the inner surface of the light guide plate 21. Of these rays ILa and ILb, the light totally reflected from the inner surface by the fine optical element 21d provided on the surface of the light guide plate 21 becomes illumination lights BLa and BLb. The illumination lights BLa and BLb are emitted in the −Z-axis direction from the back surface 21b of the light guide plate 21 toward the light diffusion reflection sheet 26. Thereafter, the illumination lights BLa and BLb are diffused and reflected by the light diffusion reflection sheet 26 to become illumination lights BLa and BLb directed in the + Z-axis direction, pass through the light guide plate 21 and exit from the surface of the light guide plate 21. When the illumination lights BLa and BLb traveling in the + Z-axis direction are emitted from the surface of the light guide plate 21, they are further diffused by the refractive action of the micro optical element 21d.
　そのため、光源群２０Ｇａ，２０Ｇｂから出射した光線ＩＬａ，ＩＬｂは、導光板２１の表面から出射するまでに、少なくとも導光板２１の厚みの２倍に相当する光学距離を伝播することになる。従って、光線ＩＬａ，ＩＬｂが、導光板２１の表面から出射するまでに、自らの発散角により拡散するための光学距離を、バックライトユニット５Ａの大きさを抑えながら確保することができる。 Therefore, the light beams ILa and ILb emitted from the light source groups 20Ga and 20Gb propagate an optical distance corresponding to at least twice the thickness of the light guide plate 21 before being emitted from the surface of the light guide plate 21. Therefore, before the light beams ILa and ILb are emitted from the surface of the light guide plate 21, it is possible to ensure an optical distance for diffusing with the divergence angle of the light guide plate 21 while suppressing the size of the backlight unit 5A.
　また、光線ＩＬａ，ＩＬｂは、微細光学素子２１ｄの光学作用により面状の光である照明光ＢＬａ，ＢＬｂに変換される。照明光ＢＬａ，ＢＬｂは、導光板２１の表面から出射するまでの光路中において光拡散反射シート２６により拡散して反射する。この光拡散作用により、照明光ＢＬａ，ＢＬｂはＸ－Ｙ平面において拡散し、光源２０，…，２０の配列方向（Ｙ軸方向）において空間的に重なり合った後に導光板２１の表面から出射する。また、上述のように照明光ＢＬａ，ＢＬｂが導光板２１の表面から出射する際、微細光学素子２１ｄ，…，２１ｄの屈折作用によりさらに拡散する。これらの光拡散作用により、バックライトユニット５Ａから出射する照明光ＢＬａ，ＢＬｂの面内輝度分布は、光源群２０Ｇａ，２０Ｇｂを構成する光源２０，…，２０の配列方向（Ｙ軸方向）において均一となる。また、同様の理由により、導光板２１の光入射端近傍以外の位置においても、輝度分布の優れた均一性を得ることが可能となる。 Further, the light beams ILa and ILb are converted into illumination lights BLa and BLb which are planar lights by the optical action of the micro optical element 21d. The illumination lights BLa and BLb are diffused and reflected by the light diffusion reflection sheet 26 in the optical path from the surface of the light guide plate 21 until it is emitted. Due to this light diffusion action, the illumination lights BLa and BLb are diffused in the XY plane, and are emitted from the surface of the light guide plate 21 after being spatially overlapped in the arrangement direction (Y-axis direction) of the light sources 20. Further, as described above, when the illumination lights BLa and BLb are emitted from the surface of the light guide plate 21, they are further diffused by the refractive action of the micro optical elements 21d,. Due to these light diffusion actions, the in-plane luminance distribution of the illumination lights BLa and BLb emitted from the backlight unit 5A is uniform in the arrangement direction (Y-axis direction) of the light sources 20,..., 20 constituting the light source groups 20Ga, 20Gb. It becomes. For the same reason, it is possible to obtain excellent uniformity in luminance distribution at positions other than the vicinity of the light incident end of the light guide plate 21.
　本実施の形態においては、上記光拡散作用を得るための構造は、画像の表示面１０ｆの法線方向、つまり、表示面１０ｆの面と垂直な方向に沿って設けられている。また導光板２１の厚みと光の反射光路を利用してバックライトユニット５Ａの厚み方向に光が拡散するための光路が効率良く設けられている。このため、バックライトユニット５Ａが液晶表示素子１０の表示面１０ｆの面内方向（Ｘ－Ｙ面の面内方向）に大型化することなく、画像表示部分を囲むキャビネット部分であるベゼルの幅を細くしたデザインを可能とし、また、バックライトユニット５Ａから出射する照明光ＢＬａ，ＢＬｂの輝度分布むらを抑制することが可能となる。 In the present embodiment, the structure for obtaining the light diffusing action is provided along the normal direction of the image display surface 10f, that is, the direction perpendicular to the surface of the display surface 10f. Further, an optical path for efficiently diffusing light in the thickness direction of the backlight unit 5A is efficiently provided by using the thickness of the light guide plate 21 and the light reflection optical path. For this reason, the backlight unit 5A does not increase in size in the in-plane direction of the display surface 10f of the liquid crystal display element 10 (in-plane direction of the XY plane), and the width of the bezel that is the cabinet portion surrounding the image display portion is increased. A thin design is possible, and it is possible to suppress uneven brightness distribution of the illumination lights BLa and BLb emitted from the backlight unit 5A.
　また、バックライトユニット５Ａは、微細光学素子２１ｄ，…，２１ｄの光学作用によりＸ軸方向に均一な輝度分布の照明光ＢＬａ，ＢＬｂを生成する。このため、バックライトユニット５Ａは、光源２０，…，２０の配列方向であるＹ軸方向とＹ軸方向と直行するＸ軸方向との両方の輝度分布むらを抑制することができる。つまり、２種類の光学素子を設ける必要がなく、光学素子間の光結合部分の数を少なくできる。これにより、光学素子間の結合部における光の損失を抑え、光利用効率が向上するとともに、部品点数が削減され組立て性が向上するといった効果も得られる。本実施の形態では、１つのバックライトユニット５Ａで面光源装置が構成されている。 The backlight unit 5A generates illumination lights BLa and BLb having a uniform luminance distribution in the X-axis direction by the optical action of the micro optical elements 21d,. For this reason, the backlight unit 5A can suppress luminance distribution unevenness in both the Y-axis direction, which is the arrangement direction of the light sources 20, ..., 20 and the X-axis direction perpendicular to the Y-axis direction. That is, it is not necessary to provide two types of optical elements, and the number of optical coupling portions between the optical elements can be reduced. As a result, the loss of light at the coupling portion between the optical elements is suppressed, the light use efficiency is improved, and the number of parts is reduced and the assemblability is improved. In the present embodiment, the surface light source device is configured by one backlight unit 5A.
　上述のように、光源２０，…，２０の配列方向と直交する方向（Ｘ軸方向）においては、導光板２１内を伝播する光線ＩＬａ，ＩＬｂの光の強度、つまり光のパワー密度に対し導光板２１の表面に設けられる微細光学素子２１ｄ，…，２１ｄの配置密度を変化させて、輝度分布の均一性が実現されている。 As described above, in the direction orthogonal to the arrangement direction of the light sources 20,..., 20 (X-axis direction), the light intensity of the light beams ILa and ILb propagating in the light guide plate 21, that is, the light power density is guided. The uniformity of the luminance distribution is realized by changing the arrangement density of the micro optical elements 21d, ..., 21d provided on the surface of the optical plate 21.
　より詳しく説明すれば、光のパワー密度の高い光入射端面２１ｅａ，２１ｅｂ近傍では微細光学素子２１ｄ，…，２１ｄの配置密度を疎とし、光のパワー密度が小さくなるＸ軸方向の中心位置の近傍においては微細光学素子２１ｄ，…，２１ｄの配置密度が密になるように、微細光学素子２１ｄ，…，２１ｄの配置密度がＸ軸方向に沿って疎から密へと連続的に変化する。これにより、導光板２１の裏面２１ｂから出射する照明光ＢＬａ，ＢＬｂのＸ軸方向における輝度分布は均一となる。 More specifically, in the vicinity of the light incident end faces 21ea, 21eb where the light power density is high, the arrangement density of the micro optical elements 21d, ..., 21d is sparse, and the vicinity of the center position in the X-axis direction where the light power density is small. , 21d, the arrangement density of the micro optical elements 21d,..., 21d continuously changes from sparse to dense along the X-axis direction so that the arrangement density of the micro optical elements 21d,. Thereby, the luminance distribution in the X-axis direction of the illumination lights BLa and BLb emitted from the back surface 21b of the light guide plate 21 becomes uniform.
　このような照明光ＢＬａ，ＢＬｂが光拡散反射シート２６により拡散し反射されて液晶表示素子１０に向かって進行する。このため、光拡散反射シート２６で反射された後、導光板２１を透過してバックライトユニット５Ａから液晶表示素子１０に向かって出射する照明光ＢＬａ，ＢＬｂは、Ｘ軸方向においても均一な輝度分布を有する。 Such illumination lights BLa and BLb are diffused and reflected by the light diffusion reflection sheet 26 and travel toward the liquid crystal display element 10. Therefore, the illumination lights BLa and BLb that are reflected by the light diffusion reflection sheet 26 and then pass through the light guide plate 21 and are emitted from the backlight unit 5A toward the liquid crystal display element 10 have uniform luminance even in the X-axis direction. Have a distribution.
　上記のようにして、本実施の形態のバックライトユニット５Ａは、面内輝度分布の均一性に優れた照明光を得ることができる。当該照明光が、光学シート１１，１２を介して液晶表示素子１０を照明することにより、輝度分布むらが抑えられた高画質な映像を表示する液晶表示装置１０１を提供することが可能となる。なお、図４は、光学シート１１の光学構造の一例を概略的に示す斜視図である。図４に示されるように、光学シート１１の表面は、複数の凸状部１１ｐ，…，１１ｐが表示面１０ｆと平行な面に沿ってＸ軸方向に規則的に配列された構造を有している。各凸状部１１ｐは、断面が三角プリズム形状をなし、凸状部１１ｐの頂角部は液晶表示素子１０側に突出し、その頂角部をなす稜線はＹ軸方向に延在している。隣接する凸状部１１ｐ，１１ｐの間隔は一定である。 As described above, the backlight unit 5A of the present embodiment can obtain illumination light with excellent uniformity of in-plane luminance distribution. When the illumination light illuminates the liquid crystal display element 10 via the optical sheets 11 and 12, it is possible to provide the liquid crystal display device 101 that displays a high-quality image with reduced luminance distribution. FIG. 4 is a perspective view schematically showing an example of the optical structure of the optical sheet 11. As shown in FIG. 4, the surface of the optical sheet 11 has a structure in which a plurality of convex portions 11p,..., 11p are regularly arranged in the X-axis direction along a plane parallel to the display surface 10f. ing. Each convex part 11p has a triangular prism shape in cross section, the apex angle part of the convex part 11p protrudes toward the liquid crystal display element 10, and the ridge line forming the apex part extends in the Y-axis direction. The interval between the adjacent convex portions 11p, 11p is constant.
　以上に説明したように、本実施の形態の液晶表示装置１０１は、複数の点光源２０，…，２０を直線上に配置した光源群２０Ｇａ，２０Ｇｂから出射された光線ＩＬａ，ＩＬｂを、少ない部品点数で簡易な光拡散構造により均一な照明光ＢＬａ，ＢＬｂに変換することができる。 As described above, the liquid crystal display device 101 according to the present embodiment reduces the light beams ILa and ILb emitted from the light source groups 20Ga and 20Gb in which the plurality of point light sources 20,. It can be converted into uniform illumination lights BLa and BLb by a simple light diffusion structure in terms of the number of points.
　また、その光拡散構造は、液晶表示装置１０１の画像表示平面（Ｘ－Ｙ平面）の法線方向（Ｚ軸方向）に沿って設けられているので、導光板２１に対してＸ軸方向やＹ軸方向に隣接するように光拡散構造を配置しなくて済む。これにより、その画像表示平面の面積に対するバックライトユニット５Ａの面積の比率を小さくすることが可能となる。つまり、良好な画質の画像を提供しながらも、画像表示部分を囲むキャビネット部分であるベゼルの幅を細くした液晶表示装置１０１を実現することが可能となる。また、導光板２１の厚みで光伝播部を設計しているため、液晶表示装置１０１の薄型化も可能となる。 Further, since the light diffusion structure is provided along the normal direction (Z-axis direction) of the image display plane (XY plane) of the liquid crystal display device 101, It is not necessary to arrange the light diffusion structure so as to be adjacent in the Y-axis direction. Thereby, the ratio of the area of the backlight unit 5A to the area of the image display plane can be reduced. That is, it is possible to realize the liquid crystal display device 101 in which the width of the bezel that is the cabinet portion surrounding the image display portion is narrowed while providing an image with good image quality. Further, since the light propagation part is designed with the thickness of the light guide plate 21, the liquid crystal display device 101 can be thinned.
　本実施の形態によれば、点光源でかつ指向性の高い光源２０，…，２０をサイドライト方式あるいはエッジライト方式の光源として採用した場合においても、簡易で小型かつ輝度分布むらを抑えた良好な画像を表示できる液晶表示装置１０１を提供することができる。 According to the present embodiment, even when the light source 20,..., 20 that is a point light source and has high directivity is adopted as a side light type or edge light type light source, it is simple and small, and excellent in suppressing unevenness in luminance distribution. The liquid crystal display device 101 capable of displaying a clear image can be provided.
　また、従来技術と比べて光源の数を減らして輝度分布むらを抑制することができ、光源の数を減らすことによる低消費電力化の効果も得られる。 Also, the luminance distribution unevenness can be suppressed by reducing the number of light sources as compared with the prior art, and the effect of reducing power consumption by reducing the number of light sources can also be obtained.
　なお、本実施の形態においては、バックライトユニット５Ａの光源に４２０ｎｍから７００ｎｍまでの非常に広い波長帯域を有する白色光を出射する複数個のＬＥＤなどの光源２０，…，２０を１次元配列した光源群２０Ｇａ，２０Ｇｂを採用したが、本発明はこれに限るものではない。たとえば、赤色、緑色および青色の単色の光を各々出射する３種類のＬＥＤ光源を、同色のＬＥＤ光源間の距離が一定となるように１次元方向に周期的に配置した光源群を採用してもよい。また、４色のＬＥＤ光源を採用する場合には、上記３種類のＬＥＤ光源に、たとえば黄色のＬＥＤ光源を加えた４色のＬＥＤ光源を１次元方向に周期的に配置した光源群を採用してもよい。 In the present embodiment, the light source 20,..., 20 such as a plurality of LEDs that emit white light having a very wide wavelength band from 420 nm to 700 nm is one-dimensionally arranged in the light source of the backlight unit 5A. Although the light source groups 20Ga and 20Gb are employed, the present invention is not limited to this. For example, a light source group is used in which three types of LED light sources each emitting single-color light of red, green, and blue are periodically arranged in a one-dimensional direction so that the distance between the LED light sources of the same color is constant. Also good. In addition, when four-color LED light sources are employed, a light source group in which four-color LED light sources, for example, a yellow LED light source is added to the above three types of LED light sources in a one-dimensional direction is employed. May be.
　一般に、間隔をおいて異なる発光色の光源を配置する場合、導光板の光入射端面近傍において各色の輝度分布むらに起因する色むらが生じる。これに対し、本実施の形態の液晶表示装置１０１のバックライトユニット５Ａによれば、間隔をおいて配置された複数の光源２０，…，２０の光を効率良く均一化することが可能であるため、輝度分布むらおよび色むらを抑制することが可能となる。 Generally, when light sources having different emission colors are arranged at intervals, color unevenness due to uneven luminance distribution of each color occurs in the vicinity of the light incident end face of the light guide plate. On the other hand, according to the backlight unit 5A of the liquid crystal display device 101 of the present embodiment, it is possible to efficiently uniformize the light from the plurality of light sources 20,. Therefore, it is possible to suppress luminance distribution unevenness and color unevenness.
　液晶表示装置１０１の液晶表示素子１０は、その内部にカラーフィルタを備えており、バックライトユニット５Ａから出射される白色光のうち、一部の波長の光のみをカラーフィルタによって透過させることにより、たとえば３色で表示する場合は、赤色、緑色、青色の表示色を抽出することで色表現が行われている。 The liquid crystal display element 10 of the liquid crystal display device 101 includes a color filter therein, and transmits only light of a part of the wavelength of white light emitted from the backlight unit 5A by the color filter. For example, when displaying in three colors, color expression is performed by extracting display colors of red, green, and blue.
　白色光のような連続スペクトルの光源の光から一部の波長帯域の光のみを切り出して表示色を得る場合、色再現範囲を広げるために表示色の色純度を高めようとすると、液晶表示素子が備えるカラーフィルタの透過波長帯域を狭く設定しなければならない。このため、従来技術では、表示色の色純度を高めようとすると、カラーフィルタを透過する光の透過光量が減少して輝度が落ちるという問題が発生する。 When obtaining a display color by cutting out only a part of the wavelength band light from the light of a continuous spectrum light source such as white light, an attempt is made to increase the color purity of the display color in order to widen the color reproduction range. It is necessary to set the transmission wavelength band of the color filter included in Narrow. For this reason, in the prior art, when the color purity of the display color is increased, there is a problem in that the amount of light transmitted through the color filter is reduced and the luminance is lowered.
　上述のように、光源として純色性の高い単色ＬＥＤ光源を採用することが可能となれば、波長帯域幅を狭くして色再現範囲の拡大したカラーフィルタを採用しても、ＬＥＤ光源から出射された光のうち、カラーフィルタを透過する際に失われる光の光量を少なくすることができる。また、ＬＥＤ光源の発光層の材料や組成を変えることにより発光波長を制御し、カラーフィルタとの波長帯域の適合性を向上させることも可能である。これらにより、本実施の形態に係る液晶表示装置１０１は、高い光利用効率と広い色再現範囲を共に実現することができる。 As described above, if a single color LED light source with high pure color can be adopted as the light source, even if a color filter with a narrow wavelength bandwidth and an expanded color reproduction range is adopted, the light source is emitted from the LED light source. Of the received light, the amount of light lost when passing through the color filter can be reduced. It is also possible to control the emission wavelength by changing the material and composition of the light emitting layer of the LED light source and improve the compatibility of the wavelength band with the color filter. As a result, the liquid crystal display device 101 according to the present embodiment can achieve both high light utilization efficiency and a wide color reproduction range.
　また、上記バックライトユニット５Ａの光源群２０Ｇａ，２０Ｇｂの光源２０として、何れもＬＥＤが採用されているが、本発明はこれに限るものではない。ＬＥＤのように発光面積が小さく高い指向性の光を発する複数の光源が間隔をおいて配置された光源ユニットをサイドライト方式の光源に適用することにより高い効果を得ることができる。たとえば、複数のレーザ光源を１次元アレイ配列してなる光源群についても、レーザ光源の出射光の発散角やレーザ光源の配置間隔、また導光板２１の厚みを最適化することにより輝度分布の均一化の効果を得ることができる。 In addition, although LEDs are employed as the light sources 20 of the light source groups 20Ga and 20Gb of the backlight unit 5A, the present invention is not limited to this. A high effect can be obtained by applying a light source unit in which a plurality of light sources emitting light having a small light emitting area and high directivity, such as LEDs, are arranged at intervals, as a side light type light source. For example, for a light source group formed by arranging a plurality of laser light sources in a one-dimensional array, the luminance distribution is uniform by optimizing the divergence angle of the emitted light of the laser light source, the arrangement interval of the laser light sources, and the thickness of the light guide plate 21 The effect of making can be obtained.
　レーザ光源は、ＬＥＤよりもさらに単色性に優れ純度の高い色を発光することが可能なため、レーザ光源をバックライトユニット５Ａ用の光源２０，…，２０として採用することにより、色再現範囲が非常に広い液晶表示装置を提供することが可能となる。また、発光面積に対する光出力を大きくすることが可能であるため光源の個数を低減することができ、サイドライト方式あるいはエッジライト方式のバックライトユニット５Ａを大型画面の表示装置に採用する際に有効である。 Since the laser light source has higher monochromaticity than LED and can emit a high-purity color, adopting the laser light source as the light source 20,..., 20 for the backlight unit 5A provides a color reproduction range. An extremely wide liquid crystal display device can be provided. In addition, since the light output with respect to the light emitting area can be increased, the number of light sources can be reduced, which is effective when the sidelight type or edge light type backlight unit 5A is used in a large screen display device. It is.
　本実施の形態においては、導光板２１は、その光入射端面２１ｅａ，２１ｅｂから入射し導光板２１内を伝播する光線ＩＬａ，ＩＬｂを、反射あるいは屈折により－Ｚ軸方向に進行する照明光ＢＬａ，ＢＬｂに変換する光学作用を有する。また、バックライトユニット５Ａに備えられる導光板２１や、導光板２１に設けられる微細光学素子２１ｄ，…，２１ｄが何れも透明部材で構成されているため、導光板２１は、光拡散反射シート２６から＋Ｚ軸方向に反射した照明光ＢＬａ，ＢＬｂを透過する作用を有する。このように、導光板２１を透明部材で形成することでバックライトユニット５Ａの光の損失を抑え、高い光利用効率を得ることが可能である。 In the present embodiment, the light guide plate 21 receives the light beams ILa and ILb that are incident from the light incident end faces 21ea and 21eb and propagate through the light guide plate 21, and propagate in the −Z-axis direction by reflection or refraction. It has an optical action to convert to BLb. Further, since the light guide plate 21 provided in the backlight unit 5A and the micro optical elements 21d,..., 21d provided on the light guide plate 21 are all made of a transparent member, the light guide plate 21 is composed of the light diffusion reflection sheet 26. From the illumination light BLa and BLb reflected in the + Z-axis direction. Thus, by forming the light guide plate 21 with a transparent member, it is possible to suppress the loss of light of the backlight unit 5A and obtain high light utilization efficiency.
　本実施の形態においては、導光板２１のＸ軸方向に対向する２端面２１ｅａ，２１ｅｂから光を入射させる構成を採用したが、本発明はこれに限るものではない。たとえば、１端面からのみ光を入射させる、あるいは４端面全てから光を入射させる構成を採用してもよい。但し、光源の配置方法によって、導光板２１内を伝播する光の導光板２１内位置と光のパワー密度との関係が異なるため、各条件に対し微細光学素子２１ｄの配置密度を最適化する必要がある。 In the present embodiment, a configuration is adopted in which light is incident from the two end faces 21ea and 21eb facing the X-axis direction of the light guide plate 21, but the present invention is not limited to this. For example, a configuration in which light is incident only from one end face or light is incident from all four end faces may be employed. However, since the relationship between the position in the light guide plate 21 of light propagating in the light guide plate 21 and the light power density differs depending on the light source arrangement method, it is necessary to optimize the arrangement density of the micro optical elements 21d for each condition. There is.
実施の形態２．
　図５は、本発明に係る実施の形態２の透過型表示装置である液晶表示装置１０２の構成を模式的に示す構成図である。また、図６は、液晶表示装置１０２のバックライトユニット５Ｂを構成する面状光源３００の概略図である。実施の形態１の液晶表示装置１０１のバックライトユニット５Ａは、光源群２０Ｇａ，２０Ｇｂとして白色ＬＥＤを備えたのに対し、実施の形態２の液晶表示装置１０２のバックライトユニット５Ｂは、光源３０Ｇａ，３０Ｇｂを構成する光源として、青色の光を出射する単色ＬＥＤ３０ａと赤色の光を出射する単色ＬＥＤ３０ｂとを備えている。また、本実施の形態では、液晶表示装置１０１の光拡散反射シート２６の代わりに、緑色の光を発する蛍光体３７を光拡散反射シート３６に塗布した蛍光体シート３８を備えている。実施の形態１で説明した液晶表示装置１０１の構成要素と同様の構成要素には、同一符号を付し、その説明を省略する。 Embodiment 2. FIG.
FIG. 5 is a configuration diagram schematically showing a configuration of a liquid crystal display device 102 which is a transmission type display device according to the second embodiment of the present invention. FIG. 6 is a schematic diagram of a planar light source 300 constituting the backlight unit 5B of the liquid crystal display device 102. The backlight unit 5A of the liquid crystal display device 101 of the first embodiment includes white LEDs as the light source groups 20Ga and 20Gb, whereas the backlight unit 5B of the liquid crystal display device 102 of the second embodiment includes the light source 30Ga, As light sources constituting 30 Gb, a single color LED 30 a that emits blue light and a single color LED 30 b that emits red light are provided. In the present embodiment, instead of the light diffusion reflection sheet 26 of the liquid crystal display device 101, a phosphor sheet 38 in which a phosphor 37 that emits green light is applied to the light diffusion reflection sheet 36 is provided. Components similar to those of the liquid crystal display device 101 described in Embodiment 1 are denoted by the same reference numerals, and description thereof is omitted.
　図５に示されるように、液晶表示装置１０２は、透過型の液晶表示素子１０と、第１の光学シートである光学シート１１と、第２の光学シートである光学シート１２と、面光源装置であるバックライトユニット５Ｂとを備えており、これら構成要素１０，１１，１２，５Ｂは、Ｚ軸方向に積層して配列されている。 As shown in FIG. 5, the liquid crystal display device 102 includes a transmissive liquid crystal display element 10, an optical sheet 11 that is a first optical sheet, an optical sheet 12 that is a second optical sheet, and a surface light source device. The constituent elements 10, 11, 12, 5B are stacked and arranged in the Z-axis direction.
　バックライトユニット５Ｂは、光源群３０Ｇａ，３０Ｇｂと、導光板３１と、緑色の光を発する蛍光体３７を光拡散反射シート３６に塗布した蛍光体シート３８とから構成されている。蛍光体シート３８は、光拡散反射シート３６と蛍光体３７とから構成されている。また、蛍光体シート３８は、自ら緑色の光を発するため、第２の面状光源としても機能する。 The backlight unit 5B includes a light source group 30Ga, 30Gb, a light guide plate 31, and a phosphor sheet 38 in which a phosphor 37 that emits green light is applied to a light diffusion reflection sheet 36. The phosphor sheet 38 is composed of a light diffuse reflection sheet 36 and a phosphor 37. Moreover, since the phosphor sheet 38 emits green light itself, it also functions as a second planar light source.
　光源群３０Ｇａ，３０Ｇｂは、導光板３１のＸ軸方向の両端面に設けられた光入射端面３１ｅａ，３１ｅｂにそれぞれ対向して配置され、光源群３０Ｇａ，３０Ｇｂから出射された光線ＩＬｃ，ＩＬｄは、導光板３１の光入射端面３１ｅａ，３１ｅｂから導光板３１の内部に入射し、導光板３１の中心方向に向かって伝播する。蛍光体シート３８は、導光板３１の液晶表示素子１０とは反対側の面３１ｂと対向し、導光板３１に対して平行になるように配置される。光源群３０Ｇａ，３０Ｇｂにおいては、図６に示されるように、青色の単色光を出射するＬＥＤ３０ａと赤色の単色光を出射するＬＥＤ３０ｂとがＹ軸方向に一定の間隔で交互に配列されている。導光板３１は、液晶表示素子１０の表示面１０ｆに対して平行に配置され、その液晶表示素子１０側の面である表面（前面）に微細光学素子３１ｄ，…，３１ｄを有する。 The light source groups 30Ga and 30Gb are arranged to face the light incident end faces 31ea and 31eb provided on both end faces in the X-axis direction of the light guide plate 31, respectively. The light beams ILc and ILd emitted from the light source groups 30Ga and 30Gb are Light enters the light guide plate 31 from the light incident end surfaces 31ea and 31eb of the light guide plate 31 and propagates toward the center of the light guide plate 31. The phosphor sheet 38 faces the surface 31 b of the light guide plate 31 opposite to the liquid crystal display element 10 and is arranged so as to be parallel to the light guide plate 31. In the light source groups 30Ga and 30Gb, as shown in FIG. 6, LEDs 30a that emit blue monochromatic light and LEDs 30b that emit red monochromatic light are alternately arranged in the Y-axis direction at regular intervals. The light guide plate 31 is arranged in parallel to the display surface 10f of the liquid crystal display element 10, and has fine optical elements 31d, ..., 31d on the surface (front surface) which is the surface on the liquid crystal display element 10 side.
　図６は、バックライトユニット５Ｂを構成する面状光源３００を＋Ｚ軸方向から見たときの構成を示す図である。光源群３０Ｇａ，３０Ｇｂを構成する光源３０ａ，３０ｂ，…，３０ａ，３０ｂは、導光板３１のＸ軸方向の２つの光入射端面３１ｅａ，３１ｅｂに対向してＹ軸方向に等間隔に配置されている。光源群３０Ｇａ，３０Ｇｂは、光源３０ａおよび光源３０ｂから構成されている。光源３０ａは青色の光線ＢＬを出射し、光源３０ｂは赤色の光線ＲＬを出射する。なお、光線ＢＬと光線ＲＬとを合わせて光線ＩＬｃ，ＩＬｄとする。導光板３１の＋Ｚ軸方向である表面側の面には、全面に微細光学素子３１ｄ，…，３１ｄが形成されている。微細光学素子３１ｄは、実施の形態１の微細光学素子２１ｄと同様の光学作用を発揮するので、光源群３０Ｇａ，３０Ｇｂから出射される光線ＩＬｃ，ＩＬｄは、導光板３１の＋Ｚ軸方向側全面で、－Ｚ軸方向に出射する面状の照明光ＢＬｃ，ＢＬｄに変換される。微細光学素子３１ｄ，…，３１ｄは、光線ＩＬｃ，ＩＬｄを反射や屈折により進行方向を変更する光学素子である。 FIG. 6 is a diagram showing a configuration when the planar light source 300 constituting the backlight unit 5B is viewed from the + Z-axis direction. The light sources 30a, 30b,..., 30a, 30b constituting the light source groups 30Ga, 30Gb are arranged at equal intervals in the Y-axis direction so as to face the two light incident end surfaces 31ea, 31eb in the X-axis direction of the light guide plate 31. Yes. The light source groups 30Ga and 30Gb are composed of a light source 30a and a light source 30b. The light source 30a emits a blue light beam BL, and the light source 30b emits a red light beam RL. Note that the light beam BL and the light beam RL are combined into light beams ILc and ILd. Fine optical elements 31d,..., 31d are formed on the entire surface of the light guide plate 31 on the surface side in the + Z-axis direction. Since the micro optical element 31d exhibits the same optical action as the micro optical element 21d of the first embodiment, the light beams ILc and ILd emitted from the light source groups 30Ga and 30Gb are spread over the entire + Z-axis direction side of the light guide plate 31. , Converted into planar illumination lights BLc and BLd emitted in the −Z-axis direction. The fine optical elements 31d,..., 31d are optical elements that change the traveling direction of the light beams ILc, ILd by reflection or refraction.
　光源群３０Ｇａ，３０Ｇｂと導光板３１とは、第１の面状光源３００として機能する。微細光学素子３１ｄ，…，３１ｄは、導光板２１に形成される微細光学素子２１ｄ，…，２１ｄと同様に凸レンズ形状をしており、２つの光入射端面３１ｅａ，３１ｅｂから導光板３１のＸ軸方向の中心位置に向けて疎から密に配置されている。これにより、照明光ＢＬｃ，ＢＬｄは面状の光を形成する。 The light source groups 30Ga and 30Gb and the light guide plate 31 function as the first planar light source 300. The fine optical elements 31d,..., 31d have a convex lens shape like the fine optical elements 21d,..., 21d formed on the light guide plate 21, and the X-axis of the light guide plate 31 from the two light incident end faces 31ea, 31eb. Arranged from sparse to dense toward the center of the direction. Thereby, the illumination lights BLc and BLd form planar light.
　導光板３１は、上述した実施の形態１の液晶表示装置１０１が備える導光板２１と同様の構造を有する。従って、導光板３１は、光源群３０Ｇａ，３０Ｇｂから出射した光線ＩＬｃ，ＩＬｄに対して同様に作用する。光源群３０Ｇａ，３０Ｇｂから出射した光線ＩＬｃ，ＩＬｄは、導光板３１内を伝播する。その際、赤色の光と青色の光は混ざり合い、光線ＩＬｃ，ＩＬｄは混色した光線となる。光線ＩＬｃ，ＩＬｄは導光板３１の＋Ｚ軸方向の面に形成された微細光学素子３１ｄ，…，３１ｄにより－Ｚ軸方向に向かう照明光ＢＬｃ，ＢＬｄに変換される。照明光ＢＬｃ，ＢＬｄは、青色の光線ＢＬと赤色の光線ＲＬとが混色した第１の面状の光である。照明光ＢＬｃ，ＢＬｄは、導光板３１の－Ｚ軸方向の裏面３１ｂから蛍光体シート３８に向けて出射される。 The light guide plate 31 has the same structure as the light guide plate 21 provided in the liquid crystal display device 101 of the first embodiment. Therefore, the light guide plate 31 acts similarly on the light beams ILc and ILd emitted from the light source groups 30Ga and 30Gb. Light rays ILc and ILd emitted from the light source groups 30Ga and 30Gb propagate through the light guide plate 31. At that time, the red light and the blue light are mixed, and the light beams ILc and ILd are mixed light beams. The light beams ILc and ILd are converted into illumination lights BLc and BLd directed in the −Z-axis direction by the micro optical elements 31d,..., 31d formed on the surface of the light guide plate 31 in the + Z-axis direction. The illumination lights BLc and BLd are first planar light in which the blue light beam BL and the red light beam RL are mixed. The illumination lights BLc and BLd are emitted toward the phosphor sheet 38 from the back surface 31b of the light guide plate 31 in the −Z-axis direction.
　蛍光体シート３８に向けて出射された照明光ＢＬｃ，ＢＬｄは、その青色の光線ＢＬの一部が蛍光体シート３８を構成する蛍光体３７の励起光として用いられ、蛍光体シート３８から緑色の照明光ＦＬが出射される。この緑色の照明光ＦＬは第２の面状の光である。なお、励起光とは、蛍光体３７の励起に用いられる光である。 In the illumination lights BLc and BLd emitted toward the phosphor sheet 38, a part of the blue light beam BL is used as excitation light of the phosphor 37 constituting the phosphor sheet 38, and the green color from the phosphor sheet 38 is increased. Illumination light FL is emitted. The green illumination light FL is second planar light. The excitation light is light used for exciting the phosphor 37.
　また、照明光ＢＬｃ，ＢＬｄは、蛍光体シート３８の＋Ｚ軸方向側に配置された蛍光体３７の表面または蛍光体シート３８の－Ｚ軸方向側に配置された光拡散反射シート３６で拡散して反射される。この反射した照明光ＢＬｃ，ＢＬｄは、蛍光体３７の励起に用いられなかった青色の光線ＢＬと赤色の光線ＲＬとが混色した光となり、第１の面状の光（照明光ＢＬｃ，ＢＬｄ）として蛍光体シート３８から＋Ｚ軸方向に出射する。同時に、この青色の光線ＢＬと赤色の光線ＲＬとからなる第１の面状の光（照明光ＢＬｃ，ＢＬｄ）は、蛍光体シート３８の蛍光体３７から出射した緑色の第２の面状の光（照明光ＦＬ）と混ざり、白色の照明光となり＋Ｚ軸方向に出射される。蛍光体シート３８の蛍光体３７から出射される光線ＦＬのうち－Ｚ軸方向に出射された光線は、光拡散反射シート３６で＋Ｚ軸方向に拡散して反射される。 Further, the illumination lights BLc and BLd are diffused by the surface of the phosphor 37 arranged on the + Z axis direction side of the phosphor sheet 38 or the light diffusion reflection sheet 36 arranged on the −Z axis direction side of the phosphor sheet 38. And reflected. The reflected illumination lights BLc and BLd are mixed light of the blue light beam BL and the red light beam RL that are not used for exciting the phosphor 37, and the first planar light (illumination light BLc and BLd). Is emitted from the phosphor sheet 38 in the + Z-axis direction. At the same time, the first planar light (illumination light BLc, BLd) composed of the blue light beam BL and the red light beam RL is emitted from the phosphor 37 of the phosphor sheet 38. It is mixed with light (illumination light FL), becomes white illumination light, and is emitted in the + Z-axis direction. Of the light beam FL emitted from the phosphor 37 of the phosphor sheet 38, the light beam emitted in the −Z-axis direction is diffused and reflected by the light diffusion reflection sheet 36 in the + Z-axis direction.
　光拡散反射シート３６としては、たとえば、ポリエチレンテレフタラートなどの樹脂を基材とした光拡散反射シートや、微細な凹凸形状を有する基板の表面に金属を蒸着させた光拡散反射シートを使用することができる。照明光ＦＬ，ＢＬｃ，ＢＬｄは、導光板３１、光学シート１２および光学シート１１を透過して液晶表示素子１０の背面１０ｂに向けて出射される。 As the light diffusion reflection sheet 36, for example, a light diffusion reflection sheet based on a resin such as polyethylene terephthalate or a light diffusion reflection sheet in which a metal is deposited on the surface of a substrate having a fine uneven shape is used. Can do. The illumination lights FL, BLc, and BLd pass through the light guide plate 31, the optical sheet 12, and the optical sheet 11 and are emitted toward the back surface 10 b of the liquid crystal display element 10.
　光源群３０Ｇａ，３０Ｇｂから出射された青色および赤色の光線ＩＬｃ，ＩＬｄは、光入射端面３１ｅａ，３１ｅｂの近傍では十分に混色していない場合がある。本実施の形態によれば、青色および赤色の光線ＩＬｃ，ＩＬｄは、導光板３１の微細光学素子３１ｄ，…，３１ｄで－Ｚ軸方向に進行する面状の照明光ＢＬｃ，ＢＬｄに変換される。また、導光板３１の裏面３１ｂから出射された照明光ＢＬｃ，ＢＬｄは、蛍光体シート３８の蛍光体３７の表面もしくは光拡散反射シート３６の反射面で拡散して反射し、再び導光板３１に戻ってくる。よって、照明光ＢＬｃ，ＢＬｄは、液晶表示素子１０の画像表示面１０ｆの法線方向と平行な光路を往復して伝播し、その光路において蛍光体シート３８で拡散されることから、導光板３１の前面において面内輝度分布の均一な面状の照明光となる。 The blue and red light beams ILc and ILd emitted from the light source groups 30Ga and 30Gb may not be sufficiently mixed in the vicinity of the light incident end faces 31ea and 31eb. According to the present embodiment, the blue and red light beams ILc and ILd are converted into planar illumination lights BLc and BLd traveling in the −Z-axis direction by the micro optical elements 31d,. . Further, the illumination lights BLc and BLd emitted from the back surface 31b of the light guide plate 31 are diffused and reflected by the surface of the phosphor 37 of the phosphor sheet 38 or the reflection surface of the light diffusion reflection sheet 36, and again reflected on the light guide plate 31. Come back. Therefore, the illumination lights BLc and BLd propagate back and forth along an optical path parallel to the normal direction of the image display surface 10f of the liquid crystal display element 10, and are diffused by the phosphor sheet 38 in the optical path. Is a planar illumination light having a uniform in-plane luminance distribution.
　また、蛍光体３７から放射される緑色の光は指向性を有さないため、例え不均一な青色の光が蛍光体３７に入射した場合であっても、照明光ＦＬは面内輝度分布が均一な緑色の面状の光となって蛍光体３７から出射する。この青色と赤色とからなる第１の面状の光（照明光ＢＬｃ，ＢＬｄ）と緑色の第２の面状の光（照明光ＦＬ）とが互いに混色して、面内輝度分布が均一な白色の第３の面状の光（照明光ＭＬ）となり液晶表示素子１０を照明する。従って、本実施の形態の液晶表示装置１０２は、簡易で小型な構成により、輝度分布むらを抑えた良好な画像を提供することができる。 Further, since the green light emitted from the phosphor 37 has no directivity, the illumination light FL has an in-plane luminance distribution even when non-uniform blue light is incident on the phosphor 37. The light is emitted from the phosphor 37 as uniform green planar light. The first planar light composed of blue and red (illumination light BLc, BLd) and the green second planar light (illumination light FL) are mixed with each other, and the in-plane luminance distribution is uniform. It becomes white third planar light (illumination light ML) and illuminates the liquid crystal display element 10. Therefore, the liquid crystal display device 102 of this embodiment can provide a good image with reduced luminance distribution with a simple and small configuration.
　一般的に、赤色や青色のＬＥＤに比べ、緑色のＬＥＤはその材料特性により発光効率が低い。そこで、本実施の形態の光源においては、高い発光効率で赤色光や青色光を直接発光するＬＥＤ３０ａ，３０ｂを採用し、一方で緑色の光は、青色光源３０ａで蛍光体を励起することにより得る。これにより、赤、緑、青の３原色ともその発光効率を向上させることが可能となるうえ、各光源から出射される光は単色性に優れているため、これらの光源を採用した液晶表示装置１０２は、色再現範囲の広い良好な画像を得ることが可能となる。 In general, green LEDs have lower luminous efficiency due to their material characteristics than red and blue LEDs. Therefore, the light source of the present embodiment employs LEDs 30a and 30b that directly emit red light and blue light with high luminous efficiency, while green light is obtained by exciting the phosphor with the blue light source 30a. . As a result, it is possible to improve the luminous efficiency of the three primary colors of red, green, and blue, and the light emitted from each light source is excellent in monochromaticity. Therefore, a liquid crystal display device employing these light sources. No. 102 can obtain a good image with a wide color reproduction range.
　本実施の形態の構成においては、導光板３１の裏面３１ｂから出射された照明光ＢＬｃ，ＢＬｄが蛍光体３７に入射し、その後、光拡散反射シート３８で反射して蛍光体３７の中を導光板３１に向かって進む。つまり、照明光ＢＬｃ，ＢＬｄは、蛍光体３７を２回通過することになる。このため、蛍光体３７に入射した照明光ＢＬｃ，ＢＬｄの光量に対する蛍光体３７が発光する量を多くすることができる。また、光拡散反射シート３６は、蛍光体３７の－Ｚ軸方向側に配置されているため、－Ｚ軸方向に向けて蛍光体３７が発光した光線の進行方向を効率良く液晶表示素子１０側の＋Ｚ軸方向に変換することができる。尚、蛍光体シート３８から出射される緑色の光の強さは、照明光ＩＬｃ，ＩＬｄの強さに対して、Ｚ軸方向における蛍光体３７の厚み、あるいはＸ－Ｙ平面における微細光学素子３１ｄ，…，３１ｄの空間的な粗密で調整される。 In the configuration of the present embodiment, the illumination lights BLc and BLd emitted from the back surface 31b of the light guide plate 31 enter the phosphor 37, and then are reflected by the light diffusion reflection sheet 38 to be guided through the phosphor 37. Proceed toward the light plate 31. That is, the illumination lights BLc and BLd pass through the phosphor 37 twice. For this reason, the quantity which the fluorescent substance 37 light-emits with respect to the light quantity of the illumination lights BLc and BLd which injected into the fluorescent substance 37 can be increased. Further, since the light diffusive reflection sheet 36 is arranged on the −Z axis direction side of the phosphor 37, the traveling direction of the light emitted by the phosphor 37 toward the −Z axis direction is efficiently changed to the liquid crystal display element 10 side. In the + Z-axis direction. The intensity of the green light emitted from the phosphor sheet 38 is the thickness of the phosphor 37 in the Z-axis direction or the minute optical element 31d in the XY plane relative to the intensity of the illumination lights ILc and ILd. ,..., 31d are adjusted in spatial density.
　また、蛍光体は、温度上昇により発光効率が下がるという特性を持っている。実施の形態２に係るバックライトユニット５Ｂの構成においては、光源群３０Ｇａ，３０Ｇｂから離れた位置に蛍光体３７を配置することができるため、蛍光体３７は、熱源となる光源群３０Ｇａ，３０Ｇｂから放射される熱の影響を受け難くすることができる。また、蛍光体３７を励起する照明光ＢＬｃ，ＢＬｄは、面状の光として蛍光体３７に向けて出射されるため、蛍光体３７に入射する励起光である照明光ＢＬｃ，ＢＬｄのパワー密度を低下させることができる。つまり、単位面積当たりの蛍光体３７に当たる照明光ＢＬｃ，ＢＬｄの光量を下げることができる。これにより、励起光が吸収され蛍光に変換されず発熱することによる蛍光体３７の温度上昇を抑制し、蛍光体３７の劣化を抑えて信頼性を向上することができる。また、蛍光体３７の温度上昇を抑えることで、蛍光体３７の発光効率の低下も抑制することができる。 In addition, the phosphor has a characteristic that the luminous efficiency decreases as the temperature rises. In the configuration of the backlight unit 5B according to the second embodiment, since the phosphor 37 can be arranged at a position away from the light source groups 30Ga and 30Gb, the phosphor 37 is separated from the light source groups 30Ga and 30Gb serving as heat sources. It can be made less susceptible to the heat radiated. Further, since the illumination lights BLc and BLd that excite the phosphor 37 are emitted toward the phosphor 37 as planar light, the power density of the illumination lights BLc and BLd that are excitation light incident on the phosphor 37 is set. Can be reduced. That is, the amount of illumination light BLc, BLd that hits the phosphor 37 per unit area can be reduced. Thereby, it is possible to suppress the temperature rise of the phosphor 37 due to the absorption of the excitation light and the heat generation without being converted to the fluorescence, and the deterioration of the phosphor 37 can be suppressed to improve the reliability. Moreover, the fall of the luminous efficiency of the fluorescent substance 37 can also be suppressed by suppressing the temperature rise of the fluorescent substance 37.
　青色と赤色との光が混色した第１の面状の光（照明光ＢＬｃ，ＢＬｄ）と、蛍光体３７の発する緑色の第２の面状の光（照明光ＦＬ）とは混色して白色の第３の面状の光（照明光ＭＬ）となる。光源群３０Ｇａ，３０Ｇｂは、たとえば、４５０ｎｍ付近にピークを有する青色の光線ＢＬを出射する光源３０ａと、６２０ｎｍ付近にピークを有する赤色の光線ＲＬを出射する光源３０ｂとで構成される。光源３０ａから出射された青色の光線ＢＬの一部は、蛍光体３７により吸収され、たとえば５３０ｎｍ付近の波長を有する光に変換されて蛍光体３７から放射される。 The first planar light (illumination light BLc, BLd), which is a mixture of blue and red light, and the green second planar light (illumination light FL) emitted by the phosphor 37 are mixed and white. The third planar light (illumination light ML). The light source groups 30Ga and 30Gb include, for example, a light source 30a that emits a blue light beam BL having a peak near 450 nm and a light source 30b that emits a red light beam RL having a peak near 620 nm. A part of the blue light beam BL emitted from the light source 30 a is absorbed by the phosphor 37, converted into light having a wavelength near, for example, 530 nm, and emitted from the phosphor 37.
　以上に説明したように、本実施の形態の液晶表示装置１０２は、複数の点光源３０ａ，３０ｂ，…，３０ａ，３０ｂを直線上に配置した光源群３０Ｇａ，３０Ｇｂから出射された光を、少ない部品点数で簡易な構成の光拡散構造を用いて輝度分布が均一な光に変換することができる。また、その光拡散構造は、液晶表示装置１０２の画像表示平面（Ｘ－Ｙ平面）の法線方向（Ｚ軸方向）に沿って設けられているので、導光板３１に対してＸ軸方向やＹ軸方向に隣接するように光拡散構造を配置しなくて済む。これにより、その画像表示平面１０ｆの面積に対するバックライトユニット５Ｂの面積の比率を小さくすることが可能となる。つまり、良好な画質の画像を提供しながらも、画像表示部分を囲むキャビネット部分であるベゼルの幅を細くした液晶表示装置１０２を実現することが可能となる。また、導光板３１の厚みで光伝播部を設計しているため、液晶表示装置１０２の薄型化も可能となる。さらに、光源群３０Ｇａ，３０Ｇｂを構成する光源として、単色性と発光効率とに優れた赤色と青色のＬＥＤ３０ａ，３０ｂと、その青色の光を励起光として緑色の光を放射する蛍光体３７を備えるため、広い色再現範囲を有しながらも低消費電力を実現する液晶表示装置１０２を提供することが可能となる。 As described above, the liquid crystal display device 102 of the present embodiment has a small amount of light emitted from the light source groups 30Ga and 30Gb in which the plurality of point light sources 30a, 30b,..., 30a, 30b are arranged on a straight line. The light diffusion structure having a simple configuration with the number of parts can be used to convert the light into a uniform luminance distribution. Further, since the light diffusion structure is provided along the normal direction (Z-axis direction) of the image display plane (XY plane) of the liquid crystal display device 102, It is not necessary to arrange the light diffusion structure so as to be adjacent in the Y-axis direction. Thereby, the ratio of the area of the backlight unit 5B to the area of the image display plane 10f can be reduced. That is, it is possible to realize the liquid crystal display device 102 in which the width of the bezel that is the cabinet portion surrounding the image display portion is narrowed while providing an image with good image quality. Further, since the light propagation part is designed with the thickness of the light guide plate 31, the liquid crystal display device 102 can be thinned. Furthermore, as light sources constituting the light source groups 30Ga and 30Gb, red and blue LEDs 30a and 30b having excellent monochromaticity and luminous efficiency, and a phosphor 37 that emits green light using the blue light as excitation light are provided. Therefore, it is possible to provide the liquid crystal display device 102 that achieves low power consumption while having a wide color reproduction range.
　本実施の形態のバックライトユニット５Ｂの光源３０ａ，３０ｂとしては、何れもＬＥＤを採用しているが、本発明はこれに限るものではない。実施の形態１に関して先に説明したように、レーザ光源を採用した場合においても面内輝度分布の均一性に対し高い効果を得ることができ、また、より単色性に優れたレーザ光源の採用はさらなる色再現範囲の拡大が可能となる。 As the light sources 30a and 30b of the backlight unit 5B of the present embodiment, both employ LEDs, but the present invention is not limited to this. As described above with respect to the first embodiment, even when a laser light source is employed, a high effect can be obtained with respect to the uniformity of the in-plane luminance distribution, and the adoption of a laser light source with superior monochromaticity can be achieved. It is possible to further expand the color reproduction range.
　また、光源群３０Ｇａ，３０Ｇｂを、上記光源３０ａ，３０ｂに代えて、紫外波長帯域を有する紫外光を発する単色のＬＥＤと赤色のＬＥＤとから構成し、この紫外光を吸収して青色から緑色の波長域の光を放射する蛍光体を採用する構成としてもよい。このとき、青色のＬＥＤ光源３０ａと緑色の蛍光体３７とを採用する場合に比べ、青色および緑色の光を蛍光体で発光するため色再現範囲が若干狭くなるが、青色と緑色の光の発光効率を向上させることが可能となるため、低消費電力化の効果を期待することができる。 The light source group 30Ga, 30Gb is composed of a single color LED and a red LED that emit ultraviolet light having an ultraviolet wavelength band, instead of the light sources 30a, 30b, and absorbs the ultraviolet light to change from blue to green. It is good also as a structure which employ | adopts the fluorescent substance which radiates | emits the light of a wavelength range. At this time, compared with the case where the blue LED light source 30a and the green phosphor 37 are adopted, the color reproduction range is slightly narrowed because the phosphor emits blue and green light. Since the efficiency can be improved, an effect of reducing power consumption can be expected.
実施の形態３．
　図７は、本発明に係る実施の形態３の透過型画像表示装置である液晶表示装置１０３の構成を模式的に示す構成図である。図８は、この液晶表示装置１０３のバックライトユニット５Ｃを構成する第１の面状光源３０１の概略構成を示す図である。また、図９は、バックライトユニット５Ｃを構成する他の面状光源４００ａの概略構成を示す図であり、図１０は、バックライトユニット５Ｃを構成するさらに他の面状光源４００ｂの概略構成を示す図である。上記実施の形態２の液晶表示装置１０２は、白色の面状の光（照明光ＭＬ）を出射するバックライトユニット５Ｂを備えたのに対し、実施の形態３の液晶表示装置１０３は、青緑色の面状の光を出射する面状光源３０１と、赤色の面状の光を出射する面状光源４００ａ，４００ｂとを有するバックライトユニット５Ｃを備えている。なお、図７及び図８において、実施の形態１および実施の形態２で説明した液晶表示装置１０１，１０２の構成要素と同様の構成要素には、同一符号を付し、その説明を省略する。 Embodiment 3 FIG.
FIG. 7 is a configuration diagram schematically showing a configuration of a liquid crystal display device 103 which is a transmissive image display device according to the third embodiment of the present invention. FIG. 8 is a diagram showing a schematic configuration of the first planar light source 301 constituting the backlight unit 5C of the liquid crystal display device 103. As shown in FIG. FIG. 9 is a diagram showing a schematic configuration of another planar light source 400a constituting the backlight unit 5C, and FIG. 10 shows a schematic configuration of still another planar light source 400b constituting the backlight unit 5C. FIG. The liquid crystal display device 102 of the second embodiment includes the backlight unit 5B that emits white planar light (illumination light ML), whereas the liquid crystal display device 103 of the third embodiment has a blue-green color. The backlight unit 5C includes a planar light source 301 that emits planar light and a planar light sources 400a and 400b that emit red planar light. 7 and 8, the same reference numerals are given to the same components as those of the liquid crystal display devices 101 and 102 described in the first and second embodiments, and the description thereof is omitted.
　図７に示されるように、液晶表示装置１０３は、透過型の液晶表示素子１０と、第１の光学シートである光学シート１１と、第２の光学シートである光学シート１２と、バックライトユニット５Ｃとを備えており、これら構成要素１０，１１，１２，５Ｃは、Ｚ軸方向に積層して配列されている。 As shown in FIG. 7, the liquid crystal display device 103 includes a transmissive liquid crystal display element 10, an optical sheet 11 that is a first optical sheet, an optical sheet 12 that is a second optical sheet, and a backlight unit. 5C, and these components 10, 11, 12, and 5C are stacked in the Z-axis direction.
　液晶表示装置１０３は、さらに、液晶表示素子１０を駆動する図示しない液晶表示素子駆動部と、バックライトユニット５Ｃに含まれる光源群３２Ｇａ，３２Ｇｂ，４０Ｇａ，４０Ｇｂを駆動する図示しない光源駆動部とを有している。液晶表示素子駆動部と光源駆動部の動作は、図示しない制御部によって制御される。制御部は図示しない信号源から供給された映像信号に画像処理を施して制御信号を生成し、これら制御信号を液晶表示素子駆動部及び光源駆動部に供給する。光源駆動部は、それぞれ、制御部からの制御信号に応じて光源群３２Ｇａ，３２Ｇｂ，４０Ｇａ，４０Ｇｂを駆動してこれら光源群３２Ｇａ，３２Ｇｂ，４０Ｇａ，４０Ｇｂから光を出射させる。 The liquid crystal display device 103 further includes a liquid crystal display element driving unit (not shown) that drives the liquid crystal display element 10 and a light source driving unit (not shown) that drives the light source groups 32Ga, 32Gb, 40Ga, and 40Gb included in the backlight unit 5C. Have. The operations of the liquid crystal display element driving unit and the light source driving unit are controlled by a control unit (not shown). The control unit performs image processing on a video signal supplied from a signal source (not shown) to generate a control signal, and supplies the control signal to the liquid crystal display element driving unit and the light source driving unit. The light source driving unit drives the light source groups 32Ga, 32Gb, 40Ga, and 40Gb in accordance with control signals from the control unit, and emits light from these light source groups 32Ga, 32Gb, 40Ga, and 40Gb, respectively.
　バックライトユニット５Ｃは、青色の光を発する光源群３２Ｇａ，３２Ｇｂと、導光板３１と、緑色の光を発する蛍光体３７を光拡散反射シート３６に塗布した蛍光体シート３８とを備えている。また、バックライトユニット５Ｃは、赤色光を発する光源群４０Ｇａ，４０Ｇｂと、赤色の面状の光を生成する２枚の導光板４１，４２とを備えている。 The backlight unit 5C includes light source groups 32Ga and 32Gb that emit blue light, a light guide plate 31, and a phosphor sheet 38 in which a phosphor 37 that emits green light is applied to a light diffusion reflection sheet 36. The backlight unit 5C includes light source groups 40Ga and 40Gb that emit red light, and two light guide plates 41 and 42 that generate red planar light.
　図７及び図８に示されるように光源群３２Ｇａ，３２Ｇｂは、導光板３１のＸ軸方向の両端面に設けられた光入射端面３１ｅａ，３１ｅｂにそれぞれ対向して配置されており、光源群３２Ｇａ，３２Ｇｂは、青色のＬＥＤ光源３０ａ，…，３０ａのみからなる。光源群３２Ｇａ，３２Ｇｂから出射された光線は、導光板３１の両端面の光入射端面３１ｅａ，３１ｅｂから導光板３１の内部に入射し、導光板３１の中心方向に向かって伝播する。このときに、微細光学素子３１ｄ，…，３１ｄは、導光板３１の内部を伝播する光線を導光板３１の全面で－Ｚ軸方向に進行する面状の照明光に変換する。この照明光の一部は、蛍光体３７を励起して緑色の面状の照明光を発生させ、照明光の他の一部は、光拡散反射シート３６で導光板３１の方向に反射する。導光板３１は、蛍光体シート３８から入射した光を透過させる。結果として、青緑色の照明光が導光板３１の前面から放射される。 As shown in FIGS. 7 and 8, the light source groups 32Ga and 32Gb are arranged to face the light incident end faces 31ea and 31eb provided on both end faces in the X-axis direction of the light guide plate 31, respectively. , 32Gb consists of only the blue LED light sources 30a, ..., 30a. Light rays emitted from the light source groups 32Ga and 32Gb are incident on the inside of the light guide plate 31 from the light incident end surfaces 31ea and 31eb on both end surfaces of the light guide plate 31, and propagate toward the center of the light guide plate 31. At this time, the micro optical elements 31d,..., 31d convert light propagating through the light guide plate 31 into planar illumination light that travels in the −Z-axis direction over the entire surface of the light guide plate 31. Part of the illumination light excites the phosphor 37 to generate green planar illumination light, and the other part of the illumination light is reflected in the direction of the light guide plate 31 by the light diffusion reflection sheet 36. The light guide plate 31 transmits the light incident from the phosphor sheet 38. As a result, blue-green illumination light is emitted from the front surface of the light guide plate 31.
　より具体的に説明すると、光源群３２Ｇａ，３２Ｇｂから出射された青色の光線は、導光板３１の＋Ｚ軸方向の面に形成された微細光学素子３１ｄ，…，３１ｄにより－Ｚ軸方向に向かう照明光に変換される。この照明光は、導光板３１の裏面３１ｂから蛍光体シート３８に向けて出射される。 More specifically, the blue light beams emitted from the light source groups 32Ga and 32Gb are illuminated toward the −Z axis direction by the micro optical elements 31d,..., 31d formed on the surface of the light guide plate 31 in the + Z axis direction. Converted to light. This illumination light is emitted from the back surface 31 b of the light guide plate 31 toward the phosphor sheet 38.
　蛍光体シート３８に向けて出射された青色の照明光の一部は、蛍光体シート３８を構成する蛍光体３７の励起光として用いられるので、蛍光体シート３８から緑色の照明光が出射される。この緑色の照明光は第２の面状の光である。蛍光体シート３８の励起に用いられなかった青色の照明光は、蛍光体シート３８の＋Ｚ軸方向側に配置された蛍光体３７の表面または蛍光体シート３８の－Ｚ軸方向側に配置された光拡散反射シート３６で反射され、第１の面状の光として蛍光体シート３８から出射される。この青色の照明光（第１の面状の光）と、蛍光体シート３８の蛍光体３７から放射された緑色の照明光（第２の面状の光）とは互いに混ざり、青緑色の照明光となり、＋Ｚ軸方向に出射される。蛍光体シート３８の蛍光体３７から放射される面状光のうち、－Ｚ軸方向に放射された光は、光拡散反射シート３６で＋Ｚ軸方向に拡散して反射される。なお、励起光とは、蛍光体の励起に用いられる光のことである。 Part of the blue illumination light emitted toward the phosphor sheet 38 is used as excitation light for the phosphor 37 constituting the phosphor sheet 38, so that green illumination light is emitted from the phosphor sheet 38. . This green illumination light is the second planar light. The blue illumination light that was not used for excitation of the phosphor sheet 38 was arranged on the surface of the phosphor 37 arranged on the + Z axis direction side of the phosphor sheet 38 or on the −Z axis direction side of the phosphor sheet 38. The light is reflected by the light diffusion reflection sheet 36 and is emitted from the phosphor sheet 38 as first planar light. The blue illumination light (first planar light) and the green illumination light (second planar light) emitted from the phosphor 37 of the phosphor sheet 38 are mixed with each other to produce a blue-green illumination. Light is emitted in the + Z-axis direction. Of the planar light emitted from the phosphor 37 of the phosphor sheet 38, the light emitted in the −Z-axis direction is diffused and reflected by the light diffusion reflection sheet 36 in the + Z-axis direction. In addition, excitation light is light used for excitation of a fluorescent substance.
　光拡散反射シート３６としては、たとえば、ポリエチレンテレフタラートなどの樹脂を基材とした光拡散反射シートや、微細な凹凸形状を有する基板の表面に金属を蒸着させた光拡散反射シートを使用することができる。 As the light diffusion reflection sheet 36, for example, a light diffusion reflection sheet based on a resin such as polyethylene terephthalate or a light diffusion reflection sheet in which a metal is deposited on the surface of a substrate having a fine uneven shape is used. Can do.
　蛍光体シート３８から放射された青緑色の照明光は、導光板３１を透過し、導光板４１，４２で赤色の照明光ＤＬａ，ＤＬｂと混ざることにより、白色の照明光を構成する。この白色の照明光は、光学シート１２および光学シート１１を透過して液晶表示素子１０の背面１０ｂを照明する。 The blue-green illumination light radiated from the phosphor sheet 38 passes through the light guide plate 31 and is mixed with the red illumination lights DLa and DLb by the light guide plates 41 and 42 to form white illumination light. The white illumination light passes through the optical sheet 12 and the optical sheet 11 and illuminates the back surface 10b of the liquid crystal display element 10.
　導光板４１，４２は、光源群４０Ｇａ，４０Ｇｂからそれぞれ出射される赤色の光線ＩＬｅ，ＩＬｆを＋Ｚ軸方向に向かう照明光ＤＬａ，ＤＬｂに変換し液晶表示素子１０の背面１０ｂに向けて出射する。これら照明光ＤＬａ，ＤＬｂは、光学シート１２と光学シート１１とを透過して液晶表示素子１０の背面１０ｂを照明する。 The light guide plates 41 and 42 convert the red light beams ILe and ILf emitted from the light source groups 40Ga and 40Gb into illumination lights DLa and DLb directed in the + Z-axis direction, respectively, and emit them toward the back surface 10b of the liquid crystal display element 10. These illumination lights DLa and DLb are transmitted through the optical sheet 12 and the optical sheet 11 to illuminate the back surface 10b of the liquid crystal display element 10.
　図９及び図１０は、面状光源４００ａおよび面状光源４００ｂの構成を概略的に示す図である。図９の面状光源４００ａは、液晶表示素子１０の表示面１０ｆに対して平行に配置された導光板４１および光源群４０Ｇａ，４０Ｇｂで構成される。一方、図１０の面状光源４００ｂは、液晶表示素子１０の表示面１０ｆに対して平行に配置された導光板４２および光源４０ｂで構成される。面状光源４００ａは、第３の面状光源であり、第４の面状の光（照明光ＤＬａ）を出射する。面状光源４００ｂは、第４の面状光源であり、第４の面状の光（照明光ＤＬｂ）を出射する。図９に面状光源４００ａを－Ｚ軸方向側から見た概略図、図１０に面状光源４００ｂを－Ｚ軸方向側から見た概略図を示す。なお、照明光ＤＬａおよび照明光ＤＬｂは第４の面状の光である。 9 and 10 are diagrams schematically showing the configuration of the planar light source 400a and the planar light source 400b. The planar light source 400a of FIG. 9 includes a light guide plate 41 and light source groups 40Ga and 40Gb arranged in parallel to the display surface 10f of the liquid crystal display element 10. On the other hand, the planar light source 400b in FIG. 10 includes a light guide plate 42 and a light source 40b arranged in parallel to the display surface 10f of the liquid crystal display element 10. The planar light source 400a is a third planar light source, and emits fourth planar light (illumination light DLa). The planar light source 400b is a fourth planar light source, and emits fourth planar light (illumination light DLb). FIG. 9 is a schematic view of the planar light source 400a viewed from the −Z axis direction side, and FIG. 10 is a schematic view of the planar light source 400b viewed from the −Z axis direction side. The illumination light DLa and the illumination light DLb are fourth planar lights.
　面状光源４００ａが有する光源群４０Ｇａを構成する光源４０ａ，…，４０ａは、導光板４１の－Ｘ軸方向側の端面である光入射端面４１ｅａに対向して配置されており、たとえば、Ｙ軸方向に沿って等間隔に配置されている。また、面状光源４００ａが有する導光板４１は、透明材料から成る板状部材であり、液晶表示素子１０とは反対側の面であり且つ－Ｚ軸方向側の面である裏面に微細光学素子４１ｄ，…，４１ｄが形成された光学素子部Ｒａを有する。光源群４０Ｇａから発せられた光線ＩＬｅは、導光板４１の光入射端面４１ｅａから導光板４１の内部に入射し、導光板４１内を全反射しながら伝播する。 The light sources 40a,..., 40a constituting the light source group 40Ga included in the planar light source 400a are disposed to face the light incident end surface 41ea that is the end surface on the −X axis direction side of the light guide plate 41. For example, the Y axis It is arranged at equal intervals along the direction. The light guide plate 41 included in the planar light source 400a is a plate-shaped member made of a transparent material, and is a surface on the opposite side of the liquid crystal display element 10 and a fine optical element on the back surface that is a surface on the −Z-axis direction side. 41d has an optical element portion Ra on which 41d is formed. The light beam ILe emitted from the light source group 40Ga enters the light guide plate 41 from the light incident end face 41ea of the light guide plate 41, and propagates through the light guide plate 41 while being totally reflected.
　同様に、面状光源４００ｂにおいては、光源群４０Ｇｂを構成する光源４０ｂ，…，４０ｂは、導光板４２の＋Ｘ軸方向側の端面である光入射端面４２ｅｂに対向して配置されており、たとえば、Ｙ軸方向に沿って等間隔に配置されている。また、面状光源４００ｂが有する導光板４２は、透明材料から成る板状部材であり、その液晶表示素子１０とは反対側の面であり且つ且つ－Ｚ軸方向側の面である裏面に微細光学素子４２ｄ，…，４２ｄが形成された光学素子部Ｒｂを有する。光源群４０Ｇｂから発せられた光は、導光板４２の光入射端面４２ｅｂから導光板４２の内部に入射し、導光板４２内を全反射しながら伝播する。微細光学素子４１ｄ，４２ｄは、光線ＩＬｅ，ＩＬｆをそれぞれ反射または屈折させて光線ＩＬｅ，ＩＬｆの進行方向を変更する光学素子として機能する。 Similarly, in the planar light source 400b, the light sources 40b,..., 40b constituting the light source group 40Gb are arranged to face the light incident end face 42eb which is the end face on the + X axis direction side of the light guide plate 42. Are arranged at equal intervals along the Y-axis direction. In addition, the light guide plate 42 included in the planar light source 400b is a plate-like member made of a transparent material. The light guide plate 42 is a surface opposite to the liquid crystal display element 10 and has a fine surface on the back side that is the surface on the −Z axis direction side. The optical element portion Rb is formed with the optical elements 42d,. The light emitted from the light source group 40Gb enters the light guide plate 42 from the light incident end face 42eb of the light guide plate 42, and propagates in the light guide plate 42 while being totally reflected. The micro optical elements 41d and 42d function as optical elements that change the traveling directions of the light beams ILe and ILf by reflecting or refracting the light beams ILe and ILf, respectively.
　面状光源４００ａと面状光源４００ｂとが有する光源群４０Ｇａ，４０Ｇｂは、互いに同じ特性を有するレーザ光源を採用しており、また光源４０ａ，…，４０ａ，４０ｂ，…，４０ｂを配置する間隔や、光源４０ａ，…，４０ａ，４０ｂ，…，４０ｂの光入射端面４１ｅａ，４２ｅｂに対する配置方向、角度等は互いに同じものとする。 The light source groups 40Ga and 40Gb included in the planar light source 400a and the planar light source 400b employ laser light sources having the same characteristics, and intervals between the light sources 40a,..., 40a, 40b,. , 40a, 40b,..., 40b have the same arrangement direction, angle, etc. with respect to the light incident end faces 41ea, 42eb.
　バックライトユニット５Ｃは、同じ特性を有する２つの面状光源４００ａ，４００ｂを有する。一方の面状光源４００ａの光学素子部Ｒａの形状と他方の面状光源４００ｂの光学素子部Ｒｂの形状とは、液晶表示素子１０の表示面１０ｆに対する法線を軸として互いに１８０度回転した関係にある。これら面状光源４００ａ，４００ｂは、導光板４１の４つの側面と導光板４２の各４つの側面とがＺ軸方向において揃うように、積層して配置されている。面状光源４００ａが有する光源群４０Ｇａと面状光源４００ｂが有する光源群４０Ｇｂとは、Ｘ軸方向において対向するように配置されており、光源群４０Ｇａは＋Ｘ軸方向に向けて光を出射し、光源群４０Ｇｂは－Ｘ軸方向に向けて光を出射する。このため、光源群４０Ｇａ，４０Ｇｂから出射される光線ＩＬｅ，ＩＬｆの進行方向は、互いに逆方向となる。面状光源４００ａ，４００ｂから出射される照明光ＤＬａ，ＤＬｂは何れも、液晶表示素子１０の背面１０ｂに向かって進行する。 The backlight unit 5C includes two planar light sources 400a and 400b having the same characteristics. The shape of the optical element portion Ra of the one planar light source 400a and the shape of the optical element portion Rb of the other planar light source 400b are rotated by 180 degrees with respect to the normal to the display surface 10f of the liquid crystal display element 10. It is in. These planar light sources 400a and 400b are stacked and arranged so that the four side surfaces of the light guide plate 41 and the four side surfaces of the light guide plate 42 are aligned in the Z-axis direction. The light source group 40Ga included in the planar light source 400a and the light source group 40Gb included in the planar light source 400b are arranged to face each other in the X-axis direction, and the light source group 40Ga emits light toward the + X-axis direction, The light source group 40Gb emits light in the −X axis direction. For this reason, the traveling directions of the light beams ILe and ILf emitted from the light source groups 40Ga and 40Gb are opposite to each other. The illumination lights DLa and DLb emitted from the planar light sources 400a and 400b travel toward the back surface 10b of the liquid crystal display element 10.
　本実施の形態におけるバックライトユニット５Ｃは、上記のように、２つの面状光源４００ａ，４００ｂが、照明光ＤＬａ，ＤＬｂの進行方向（＋Ｚ軸方向）に積層して配置される構成を有する。このため、バックライトユニット５Ｃが有する光源群４０Ｇａ，４０Ｇｂを点灯した際にバックライトユニット５Ｃから出射される照明光ＤＬは、２つの面状光源４００ａ，４００ｂから出射される照明光ＤＬａ，ＤＬｂが足し合わされたものである。従って、バックライトユニット５Ｃから出射される照明光ＤＬのＸ－Ｙ平面における面内輝度分布は、前記２つの面状光源４００ａ，４００ｂのＸ－Ｙ平面における面内輝度分布の足し合わせたものとなる。 The backlight unit 5C in the present embodiment has a configuration in which the two planar light sources 400a and 400b are stacked in the traveling direction of the illumination lights DLa and DLb (+ Z axis direction) as described above. For this reason, when the light source groups 40Ga and 40Gb included in the backlight unit 5C are turned on, the illumination light DL emitted from the backlight unit 5C is the illumination lights DLa and DLb emitted from the two planar light sources 400a and 400b. It has been added. Therefore, the in-plane luminance distribution in the XY plane of the illumination light DL emitted from the backlight unit 5C is the sum of the in-plane luminance distributions in the XY plane of the two planar light sources 400a and 400b. Become.
　導光板４１，４２は、透明部材で形成された、たとえば厚み２ｍｍの板状部材である。図７、図９及び図１０に示すように、光学素子部Ｒａ，Ｒｂには、液晶表示素子１０とは反対側の面となる裏面に半球状の凸形状（以後、凸レンズ形状と呼ぶ。）の微細光学素子４１ｄ，…，４１ｄ，４２ｄ，…，４２ｄが形成されている。これら微細光学素子４１ｄ，４２ｄは、導光板４１，４２内を伝播する光線ＩＬｅ，ＩＬｆを、液晶表示素子１０の背面１０ｂの方向（＋Ｚ軸方向）に向けて進行する照明光ＤＬａ，ＤＬｂに変換する。 The light guide plates 41 and 42 are formed of a transparent member, for example, a plate member having a thickness of 2 mm. As shown in FIGS. 7, 9, and 10, the optical element portions Ra and Rb have a hemispherical convex shape (hereinafter referred to as a convex lens shape) on the back surface that is the surface opposite to the liquid crystal display element 10. , 41d, 42d,..., 42d are formed. These micro optical elements 41d and 42d convert the light beams ILe and ILf propagating through the light guide plates 41 and 42 into illumination lights DLa and DLb traveling in the direction of the back surface 10b of the liquid crystal display element 10 (+ Z axis direction). To do.
　光入射端面４１ｅａ，４２ｅｂからそれぞれ導光板４１，４２に入射した光線ＩＬｅ，ＩＬｆは、導光板４１，４２と空気層との界面における全反射により導光板４１，４２内を、反射を繰り返しながらＸ軸方向に進行する。光線ＩＬｅ，ＩＬｆのうち、導光板４１，４２の前面と空気層との界面における全反射条件を満たさなくなる光線が存在する。その光線は、導光板４１，４２の前面から液晶表示素子１０の背面１０ｂに向かって出射される。 The light beams ILe and ILf incident on the light guide plates 41 and 42 from the light incident end surfaces 41ea and 42eb, respectively, are repeatedly reflected inside the light guide plates 41 and 42 by total reflection at the interface between the light guide plates 41 and 42 and the air layer. Progress in the axial direction. Among the light beams ILe and ILf, there are light beams that do not satisfy the total reflection condition at the interface between the front surfaces of the light guide plates 41 and 42 and the air layer. The light rays are emitted from the front surfaces of the light guide plates 41 and 42 toward the back surface 10b of the liquid crystal display element 10.
　導光板４１，４２の光学素子部Ｒａ，Ｒｂに設けられた微細光学素子４１ｄ，…，４１ｄ，４２ｄ，…，４２ｄは、Ｘ－Ｙ平面内に形成され、微細光学素子４１ｄ，…，４１ｄ，４２ｄ，…，４２ｄの配置密度（すなわち単位面積当たりの数やその大きさなど）が空間的に変化する。これにより、導光板４１，４２から出射される照明光ＤＬａ，ＤＬｂの面内輝度分布を制御することが可能となる。本実施の形態においては、図９に示すように、光線ＩＬｅの進行方向（図９中＋Ｘ軸方向）において導光板４１の光入射端面４１ｅａから離れるにつれて微細光学素子４１ｄ，…，４１ｄの配置密度が変化する構造が採用されている。同様に、図１０に示すように、光線ＩＬｆの進行方向（図１０中－Ｘ軸方向）において導光板４２の光入射端面４２ｅｂから離れるにつれて微細光学素子４２ｄ，…，４２ｄの配置密度が変化する構造が採用されている。 41d,..., 42d provided in the optical element portions Ra, Rb of the light guide plates 41, 42 are formed in the XY plane, and the micro optical elements 41d,. The arrangement density of 42d,..., 42d (that is, the number per unit area and the size thereof) varies spatially. Thereby, it is possible to control the in-plane luminance distribution of the illumination lights DLa and DLb emitted from the light guide plates 41 and 42. In the present embodiment, as shown in FIG. 9, the arrangement density of the micro optical elements 41d,..., 41d increases as the distance from the light incident end surface 41ea of the light guide plate 41 in the traveling direction of the light beam ILe (the + X-axis direction in FIG. 9). A structure that changes is adopted. Similarly, as shown in FIG. 10, the arrangement density of the micro optical elements 42d,..., 42d changes with distance from the light incident end face 42eb of the light guide plate 42 in the traveling direction of the light beam ILf (−X axis direction in FIG. 10). Structure is adopted.
　より詳しく説明すると、図９に示されるように、微細光学素子４１ｄは、導光板４１における光入射端面４１ｅａの近傍には配置されておらず、導光板４１のＸ軸方向の約中心の位置から光入射端面４１ｅａと対向する端面までの領域Ｒａに設けられている。その配置密度はＸ軸方向の中心位置の近傍から導光板４１の当該端面に向かうにつれて疎から密へと連続的に変化する。一方、図１０に示されるように、微細光学素子４２ｄは、導光板４２における光入射端面４２ｅｂの近傍には配置されておらず、導光板４２のＸ軸方向の約中心の位置から光入射端面４２ｅｂと対向する端面までの領域Ｒｂに設けられている。その配置密度はＸ軸方向の中心位置の近傍から導光板４２の当該端面に向かうにつれて疎から密へと連続的に変化する。 More specifically, as shown in FIG. 9, the micro optical element 41 d is not arranged in the vicinity of the light incident end face 41 ea in the light guide plate 41, but from the position of the approximately center of the light guide plate 41 in the X-axis direction. It is provided in the region Ra up to the end surface facing the light incident end surface 41ea. The arrangement density continuously changes from sparse to dense as it goes from the vicinity of the center position in the X-axis direction toward the end face of the light guide plate 41. On the other hand, as shown in FIG. 10, the micro optical element 42 d is not disposed in the vicinity of the light incident end surface 42 eb in the light guide plate 42, and the light incident end surface from the position about the center of the light guide plate 42 in the X-axis direction. It is provided in the region Rb up to the end surface facing 42eb. The arrangement density continuously changes from sparse to dense as it goes from the vicinity of the center position in the X-axis direction toward the end face of the light guide plate 42.
　微細光学素子４１ｄ，４２ｄの表面形状としては、たとえば、導光板２１，３１の微細光学素子２１ｄ，３１ｄと同様に、曲率が約０．１５ｍｍ、最大高さが約０．００５ｍｍの凸レンズ形状を採用できる。微細光学素子４１ｄ，４２ｄの屈折率は約１．４９とすればよい。なお、導光板４１，４２や微細光学素子４１ｄ，４２ｄの材質はアクリル樹脂とすることができるが、この材質に限定されるものではない。光透過率が良く、成形加工性に優れた材質であれば、アクリル樹脂に代えてポリカーボネート樹脂などの他の樹脂材料、あるいはガラス材料を使用してもよい。 As the surface shape of the micro optical elements 41d and 42d, for example, a convex lens shape having a curvature of about 0.15 mm and a maximum height of about 0.005 mm is employed, as with the micro optical elements 21d and 31d of the light guide plates 21 and 31. it can. The refractive index of the micro optical elements 41d and 42d may be about 1.49. The light guide plates 41 and 42 and the micro optical elements 41d and 42d can be made of acrylic resin, but are not limited to this material. As long as the material has good light transmittance and excellent moldability, other resin materials such as polycarbonate resin or glass material may be used instead of acrylic resin.
　また、本実施の形態においては、微細光学素子４１ｄ，４２ｄの表面形状を凸レンズ形状としたが、本発明はこれに限るものではない。微細光学素子４１ｄ，４２ｄは、導光板４１，４２内をＸ軸方向に進行する光線ＩＬｅ，ＩＬｆを、Ｚ軸方向に内面全反射させて液晶表示素子１０の背面１０ｂに向かって出射させる構造を有していれば、他の形状でもよく、たとえば、プリズム形状や、サンドブラスト等によるランダムな凹凸パターンから成る微細光学素子を採用してもよい。 In the present embodiment, the surface shapes of the micro optical elements 41d and 42d are convex lens shapes, but the present invention is not limited to this. The micro optical elements 41d and 42d have a structure in which the light beams ILe and ILf traveling in the X-axis direction through the light guide plates 41 and 42 are totally reflected in the Z-axis direction and emitted toward the back surface 10b of the liquid crystal display element 10. As long as it has, other shapes may be used. For example, a fine optical element having a prism shape or a random concavo-convex pattern such as sandblast may be adopted.
　ただし、凸レンズ形状の場合、透明な構造で光を屈折することが可能で、プリズム等の構造に比べて簡易な形状であるため製作が容易であるという利点がある。また、導光板４１，４２が大型化した場合でも、印刷による製作が可能であるため、導光板４１，４２の大型化に容易に対応することができる。また、サンドブラスト等によるランダムな凹凸形状でもレーザ光をＺ軸方向に屈折することはできるが、凸レンズ形状の場合は、凸形状の設計が可能であるため、均一な輝度分布を実現する面状光源４００ａ，４００ｂの設計が容易であるという利点がある。 However, in the case of a convex lens shape, there is an advantage that light can be refracted with a transparent structure, and since it has a simpler shape than a structure such as a prism, it is easy to manufacture. Further, even when the light guide plates 41 and 42 are increased in size, the light guide plates 41 and 42 can be easily coped with because the light guide plates 41 and 42 can be manufactured by printing. Laser light can be refracted in the Z-axis direction even with random uneven shapes such as sandblasting, but in the case of a convex lens shape, a convex shape can be designed, so a planar light source that realizes a uniform luminance distribution There is an advantage that the design of 400a and 400b is easy.
　本実施の形態においては、導光板４１，４２の厚みを２ｍｍとしたが、本発明はこれに限るものではない。液晶表示装置１０３の薄型化、軽量化、さらには多重反射回数の増加による光の利用効率向上といった点においては、厚みの薄い導光板４１，４２を採用することが望ましい。レーザ光源は、発光面の面積が小さく且つ指向性が高い光源であるから、厚みの薄い導光板に対しても高い光結合効率を得ることが可能である。但し、このとき、導光板４１，４２の厚みを薄型化することによる剛性低下の問題等も考慮する必要がある。 In the present embodiment, the thickness of the light guide plates 41 and 42 is 2 mm, but the present invention is not limited to this. In terms of reducing the thickness and weight of the liquid crystal display device 103 and improving the light utilization efficiency by increasing the number of multiple reflections, it is desirable to use the light guide plates 41 and 42 having a small thickness. Since the laser light source is a light source having a small light emitting surface area and high directivity, it is possible to obtain high optical coupling efficiency even for a light guide plate having a small thickness. However, at this time, it is also necessary to consider the problem of reduced rigidity caused by reducing the thickness of the light guide plates 41 and 42.
　光源４０ａ，…，４０ａ，４０ｂ，…，４０ｂとしてレーザ光源を採用した光源群４０Ｇａ，４０Ｇｂは、６４０ｎｍをピーク波長とし、波長幅が半値全幅で１ｎｍの極めて単色性の高いスペクトルを有する光を出射することができる。また、たとえば、その発散角は速軸方向においては半値全幅で４０度、遅軸方向においては半値全幅で１０度である。本実施の形態においては、光源群４０Ｇａ，４０Ｇｂのレーザ光源は、その速軸方向が導光板４１，４２の光入射端面４１ｅａ，４２ｅｂの短辺方向と平行になるように配置されることが好ましい。これは、発散角の大きい速軸方向が、導光板４１，４２の光入射端面４１ｅａ，４２ｅｂにおける短辺方向、すなわち導光板４１，４２の対向する面と面の間隔が最も狭くなる方向（図７中ではＺ軸方向）と平行となることにより、光線ＩＬｅ，ＩＬｆの導光板４１，４２内での反射回数が増大し、導光板４１，４２に設けられる微細光学素子４１ｄ，４２ｄに入射する光線が多くなるためである。これにより、微細光学素子４１ｄ，４２ｄによる光の取り出し効率（＝液晶表示素子１０の方向に向かって出射される光量／導光板４１，４２内を伝播する光量）を向上させることが可能となる。 A light source group 40Ga, 40Gb that employs laser light sources as the light sources 40a, ..., 40a, 40b, ..., 40b emits light having a very monochromatic spectrum with a peak wavelength of 640 nm and a full width at half maximum of 1 nm. can do. Further, for example, the divergence angle is 40 degrees with the full width at half maximum in the fast axis direction and 10 degrees with the full width at half maximum in the slow axis direction. In the present embodiment, the laser light sources of the light source groups 40Ga and 40Gb are preferably arranged so that the fast axis direction thereof is parallel to the short side direction of the light incident end faces 41ea and 42eb of the light guide plates 41 and 42. . This is because the fast axis direction with a large divergence angle is the short side direction of the light incident end faces 41ea and 42eb of the light guide plates 41 and 42, that is, the direction in which the distance between the opposing surfaces of the light guide plates 41 and 42 is the narrowest (see FIG. 7, the number of times the light beams ILe and ILf are reflected within the light guide plates 41 and 42 increases, and enters the micro optical elements 41 d and 42 d provided on the light guide plates 41 and 42. This is because the number of rays increases. Thereby, it is possible to improve the light extraction efficiency (= the amount of light emitted toward the direction of the liquid crystal display element 10 / the amount of light propagating through the light guide plates 41 and 42) by the micro optical elements 41d and 42d.
　本実施の形態によると、光源群４０Ｇａ，４０Ｇｂから出射される光線ＩＬｅ，ＩＬｆの光径は、光入射端面４１ｅａ，４２ｅｂのＹ軸方向の大きさに対し極めて小さい。導光板４１，４２の光入射端面４１ｅａ，４２ｅｂの近傍に設けられる光伝播部Ｐａ，Ｐｂに対応する領域には、微細光学素子４１ｄ，４２ｄが形成されていない。このため、光線ＩＬｅ，ＩＬｆは、光伝播部Ｐａ，Ｐｂにおいて十分な光学距離を全反射しながら伝播することができる。よって、光線ＩＬｅ，ＩＬｆは、自らの発散角により拡がり、隣接する他の光線と空間的に重なり合うことによりＹ軸方向における輝度分布が均一な線状の光、つまり線状光を形成する。 According to the present embodiment, the light diameters of the light beams ILe and ILf emitted from the light source groups 40Ga and 40Gb are extremely small with respect to the size of the light incident end faces 41ea and 42eb in the Y-axis direction. Fine optical elements 41d and 42d are not formed in regions corresponding to the light propagation portions Pa and Pb provided in the vicinity of the light incident end surfaces 41ea and 42eb of the light guide plates 41 and 42, respectively. For this reason, the light beams ILe and ILf can propagate while totally reflecting a sufficient optical distance in the light propagation portions Pa and Pb. Therefore, the light beams ILe and ILf are spread by their divergence angles and spatially overlap with other adjacent light beams to form linear light having a uniform luminance distribution in the Y-axis direction, that is, linear light.
　図１１は、隣り合う２つの光源から出射する光線が一定の光学距離を伝播することによって線状光となることを説明する概念図である。図１１に示すように、Ｘ軸方向の任意の位置における、単一の光源から出射した光線のＹ軸方向の輝度分布６０は、光線が元々有するガウシアン形状の角度輝度分布に起因して、中心輝度が高く、中心から離れるにつれ急激に輝度が低下するような形状を有する。そのため、単一の光線が光学素子部に入射すると、当該光線の輝度分布が導光板から出射される照明光の面内輝度分布に反映されて輝度分布むらを生じさせる。 FIG. 11 is a conceptual diagram for explaining that light beams emitted from two adjacent light sources become linear light by propagating a certain optical distance. As shown in FIG. 11, the luminance distribution 60 in the Y-axis direction of a light beam emitted from a single light source at an arbitrary position in the X-axis direction is caused by the Gaussian-shaped angular luminance distribution originally possessed by the light beam. The brightness is high, and the shape is such that the brightness rapidly decreases as the distance from the center increases. Therefore, when a single light beam enters the optical element unit, the luminance distribution of the light beam is reflected in the in-plane luminance distribution of the illumination light emitted from the light guide plate, thereby causing uneven luminance distribution.
　しかしながら、近接して配置される複数の光源から出射される複数の光線を空間的に重ね合わせると、Ｙ軸方向である光源配列方向に均一な輝度分布を有する線状光源を作り出すことができる。たとえば、図１１中の輝度分布６０を有する単一の光線と輝度分布６１を有する単一の光線とを重ね合わせると、それらの分布が平均化され、輝度分布６２のような均一の輝度分布となる。従って、単一の光線では均一でない分布を有する光であっても、複数の光線を空間的に重ね合わせることによって、それらの分布を平均化することができるため、光源配列方向において輝度分布が均一な線状光源を作り出すことが可能となる。 However, when a plurality of light beams emitted from a plurality of light sources arranged close to each other are spatially superimposed, a linear light source having a uniform luminance distribution in the light source arrangement direction that is the Y-axis direction can be created. For example, when a single ray having the luminance distribution 60 in FIG. 11 and a single ray having the luminance distribution 61 are superimposed, the distributions are averaged, and a uniform luminance distribution such as the luminance distribution 62 is obtained. Become. Therefore, even if the light has a non-uniform distribution with a single light beam, the light distribution can be averaged by spatially superimposing a plurality of light beams, so that the luminance distribution is uniform in the light source array direction. It becomes possible to create a simple linear light source.
　このように、近接する光源の光を重ね合わせるためには、光源群４０Ｇａ，４０Ｇｂの発する光の発散角と光源４０ａ，…，４０ａ，４０ｂ，…，４０ｂの配置間隔とにより決まる一定以上の光学距離を、光線ＩＬｅ，ＩＬｆが伝播する必要がある。実施の形態３の面状光源４００ａ，４００ｂが有する導光板４１，４２は、光線ＩＬｅ，ＩＬｆが微細光学素子４１ｄ，４２ｄに入射するまでに伝播する光伝播部Ｐａ，Ｐｂを備えている。これら光伝播部Ｐａ，Ｐｂは、光線ＩＬｅ，ＩＬｆが自らの発散角で光源４０ａ，…，４０ａ，４０ｂ，…，４０ｂの配列方向（Ｙ軸方向）で空間的に十分に拡がるために必要な光学距離を備えている。このため、光線ＩＬｅ，ＩＬｆは、均一性の高い線状光となった後に、微細光学素子４１ｄ，４２ｄが形成された光学素子部Ｒａ，Ｒｂに入射することが可能となる。 As described above, in order to superimpose the light of the adjacent light sources, a certain level or more of optics determined by the divergence angles of the light emitted from the light source groups 40Ga and 40Gb and the arrangement intervals of the light sources 40a,. Light rays ILe and ILf need to propagate through the distance. The light guide plates 41 and 42 included in the planar light sources 400a and 400b according to the third embodiment include light propagation portions Pa and Pb that propagate until the light beams ILe and ILf enter the micro optical elements 41d and 42d. These light propagation portions Pa and Pb are necessary for the light beams ILe and ILf to be sufficiently spread spatially in the arrangement direction (Y-axis direction) of the light sources 40a,..., 40a, 40b,. Has optical distance. For this reason, the light beams ILe and ILf can be incident on the optical element portions Ra and Rb on which the micro optical elements 41d and 42d are formed after becoming highly uniform linear light.
　また、実施の形態３では、光源群４０Ｇａ，４０Ｇｂを構成する光源４０ａ，…，４０ａ，４０ｂ，…，４０ｂは、等しい発散角と角度輝度分布を有する光を発し、等間隔で配置された構成をとるため、より輝度分布の均一性が高い線状の光が得られる。 In the third embodiment, the light sources 40a,..., 40a, 40b,..., 40b constituting the light source groups 40Ga, 40Gb emit light having the same divergence angle and angular luminance distribution, and are arranged at equal intervals. Therefore, linear light with higher uniformity of luminance distribution can be obtained.
　上記のようにして、線状の光となって光学素子部Ｒａ，Ｒｂに入射する光線ＩＬｅ，ＩＬｆは、導光板４１，４２の裏面の微細光学素子４１ｄ，４２ｄにより光線の一部が内面反射により照明光ＤＬａ，ＤＬｂに変換されて導光板４１，４２の表面から液晶表示素子１０の背面１０ｂに向けて出射される。このとき、微細光学素子４１ｄ，４２ｄに入射する光線ＩＬｅ，ＩＬｆは、光源４０ａ，…，４０ａ，４０ｂ，…，４０ｂの配列方向（Ｙ軸方向）において均一な線状の光となっているので、光源４０ａ，…，４０ａ，４０ｂ，…，４０ｂにおける輝度分布の差による輝度分布むらを生じることなく、均一な照明光ＤＬとして、液晶表示素子１０を照明する。 As described above, the light beams ILe and ILf that enter the optical element portions Ra and Rb as linear light are partially reflected internally by the micro optical elements 41d and 42d on the back surfaces of the light guide plates 41 and 42. Is converted into illumination light DLa and DLb and emitted from the surface of the light guide plates 41 and 42 toward the back surface 10b of the liquid crystal display element 10. At this time, the light beams ILe and ILf incident on the micro optical elements 41d and 42d are uniform linear light in the arrangement direction (Y-axis direction) of the light sources 40a, ..., 40a, 40b, ..., 40b. , 40a, 40b,..., 40b illuminate the liquid crystal display element 10 as uniform illumination light DL without causing uneven luminance distribution.
　上記の通り、面状光源４００ａ，４００ｂは、光線ＩＬｅ，ＩＬｆの進行方向であるＸ軸方向において、それぞれ点光源である光源４０ａ，４０ｂから出射した光線ＩＬｅ，ＩＬｆを線状の光に変換するための光伝播部Ｐａ，Ｐｂが設けられている。このため、面状光源４００ａ，４００ｂは、照明光ＤＬａ，ＤＬｂを出射しない領域を有している。 As described above, the planar light sources 400a and 400b convert the light beams ILe and ILf emitted from the light sources 40a and 40b, which are point light sources, into linear light in the X-axis direction, which is the traveling direction of the light beams ILe and ILf, respectively. Light propagation portions Pa and Pb are provided. For this reason, the planar light sources 400a and 400b have areas where the illumination lights DLa and DLb are not emitted.
　本実施の形態においては、面状光源４００ａ，４００ｂは、照明光ＤＬａ，ＤＬｂを発光しない領域（光伝播部Ｐａ，Ｐｂ）を補い合うように積層配置されている。つまりは、面状光源４００ａが発光しない領域と面状光源４００ｂが発光する領域とがＺ軸方向に積層されており、面状光源４００ｂが発光しない領域と面状光源４００ａが発光する領域とがＺ軸方向に積層されている。このため、面状光源４００ａと面状光源４００ｂとの組み合わせが面全体から照明光を出射することが可能となる。 In the present embodiment, the planar light sources 400a and 400b are stacked and arranged so as to supplement regions (light propagation portions Pa and Pb) that do not emit the illumination lights DLa and DLb. That is, the area where the planar light source 400a does not emit light and the area where the planar light source 400b emits light are stacked in the Z-axis direction, and the area where the planar light source 400b does not emit light and the area where the planar light source 400a emits light. They are stacked in the Z-axis direction. For this reason, the combination of the planar light source 400a and the planar light source 400b can emit illumination light from the entire surface.
　さらに、本実施の形態においては、面状光源４００ａと面状光源４００ｂとのＸ軸方向における輝度分布が足し合わされて輝度分布が均一となるよう、各々の輝度分布を決定する微細光学素子４１ｄ，４２ｄのＸ軸方向における配置密度が最適化されている。 Furthermore, in the present embodiment, the fine optical elements 41d, which determine the respective luminance distributions such that the luminance distributions in the X-axis direction of the planar light source 400a and the planar light source 400b are added to make the luminance distribution uniform. The arrangement density in the X-axis direction of 42d is optimized.
　図１２は、面状光源４００ａと面状光源４００ｂとから出射される照明光ＤＬａ，ＤＬｂのＸ軸方向における１次元輝度分布のシミュレーションによる計算結果を示すグラフである。より詳しく説明すると、図１２は、面状光源４００ａのＸ軸方向における１次元輝度分布５０と、面状光源４００ｂのＸ軸方向における１次元輝度分布５１と、両者の輝度分布５０，５１を足し合わせたＸ軸方向における１次元輝度分布５２とのシミュレーションによる計算結果を示すグラフである。 FIG. 12 is a graph showing a calculation result by simulation of a one-dimensional luminance distribution in the X-axis direction of the illumination lights DLa and DLb emitted from the planar light source 400a and the planar light source 400b. More specifically, FIG. 12 adds the one-dimensional luminance distribution 50 in the X-axis direction of the planar light source 400a, the one-dimensional luminance distribution 51 in the X-axis direction of the planar light source 400b, and both luminance distributions 50 and 51. It is a graph which shows the calculation result by simulation with the combined one-dimensional luminance distribution 52 in the X-axis direction.
　図１２より明らかなように、面状光源４００ａから出射する照明光ＤＬａの１次元輝度分布５０は、－Ｘ軸方向側に配置された光入射端面４１ｅａ側から導光板４１のＸ軸方向の中心位置の近傍にかけては光が出射されていない。一方、導光板４１のＸ軸方向における中心位置の近傍から＋Ｘ軸方向に向けて徐々に輝度が高くなり、＋Ｘ軸方向である光入射端面４１ｅａと対向する端面の近傍付近では一定の輝度を保つ。一方、面状光源４００ｂから出射される照明光ＤＬｂの１次元輝度分布５１は、面状光源４００ａの１次元輝度分布５０とは逆転する輝度分布を有しており、＋Ｘ軸方向である光入射端面４２ｅｂ側から導光板４２のＸ軸方向の中心位置の近傍にかけては光が出射されず、導光板４２のＸ軸方向における中心位置の近傍から－Ｘ軸方向に向けて徐々に輝度が高くなり、－Ｘ軸方向である光入射端面４２ｅｂと対向する端面の近傍付近では一定の輝度を保つ。 As is clear from FIG. 12, the one-dimensional luminance distribution 50 of the illumination light DLa emitted from the planar light source 400a is the center of the light guide plate 41 in the X-axis direction from the light incident end face 41ea arranged on the −X-axis direction side. No light is emitted near the position. On the other hand, the luminance gradually increases from the vicinity of the center position of the light guide plate 41 in the X-axis direction toward the + X-axis direction, and maintains a constant luminance in the vicinity of the end surface facing the light incident end surface 41ea in the + X-axis direction. . On the other hand, the one-dimensional luminance distribution 51 of the illumination light DLb emitted from the planar light source 400b has a luminance distribution that is opposite to the one-dimensional luminance distribution 50 of the planar light source 400a, and light incident in the + X axis direction. No light is emitted from the end face 42eb to the vicinity of the center position of the light guide plate 42 in the X axis direction, and the luminance gradually increases from the vicinity of the center position of the light guide plate 42 in the X axis direction toward the -X axis direction. In the vicinity of the end surface facing the light incident end surface 42eb in the −X axis direction, a constant luminance is maintained.
　つまり、照明光ＤＬａおよび照明光ＤＬｂは、導光板４１，４２のＸ軸方向の約中央付近で重なるように出射されている。ここで、微細光学素子４１ｄ，４２ｄの配列を疎から密へ変化させることで液晶表示素子１０の方向に出射される光の光量を徐々に増加するようにしている。このため、照明光ＤＬａと照明光ＤＬｂとの重なる部分でも、容易にそれらの足し合わせた光量を他の部分と同一の光量とすることができ、面状光源４００ａの照明光ＤＬａと面状光源４００ｂの照明光ＤＬｂとのつなぎ目で光量の低下を抑制し、または光量の増加による輝度分布むらを抑えることがきる。 That is, the illumination light DLa and the illumination light DLb are emitted so as to overlap in the vicinity of the center of the light guide plates 41 and 42 in the X-axis direction. Here, the amount of light emitted toward the liquid crystal display element 10 is gradually increased by changing the arrangement of the micro optical elements 41d and 42d from sparse to dense. For this reason, even in the portion where the illumination light DLa and the illumination light DLb overlap, the amount of light added together can be easily made the same as that of the other portions, and the illumination light DLa of the planar light source 400a and the planar light source It is possible to suppress a decrease in the amount of light at the joint with the illumination light DLb of 400b or suppress unevenness in luminance distribution due to an increase in the amount of light.
　面状光源４００ａから出射される照明光ＤＬａと面状光源４００ｂから出射される照明光ＤＬｂとの足し合わせにより生成される照明光の面内輝度分布５２は、Ｘ軸方向において均一な分布となる。本実施の形態の構成に従い試作した面状光源４００ａ，４００ｂから出射あｓれる照明光の面内輝度分布を実際に計測した結果を図１３に示す。図１３より明らかなように、２つの面状光源４００ａ，４００ｂをＺ軸方向に積層した構成において、光線の進行方向（Ｘ軸方向）において均一性に優れた照明光が得られることが分かる。 The in-plane luminance distribution 52 of the illumination light generated by adding the illumination light DLa emitted from the planar light source 400a and the illumination light DLb emitted from the planar light source 400b becomes a uniform distribution in the X-axis direction. . FIG. 13 shows the result of actually measuring the in-plane luminance distribution of the illumination light emitted from the planar light sources 400a and 400b manufactured according to the configuration of the present embodiment. As can be seen from FIG. 13, in the configuration in which the two planar light sources 400a and 400b are stacked in the Z-axis direction, illumination light having excellent uniformity in the traveling direction of the light beam (X-axis direction) can be obtained.
　以下に、光源群４０Ｇａに含まれるレーザ光源８０（４０ａ）と、それとＹ軸方向に隣り合うレーザ光源８１（４０ａ）を例に挙げ、導光板４１に備えられる光伝播部Ｐａについて詳しく説明する。 Hereinafter, the laser light source 80 (40a) included in the light source group 40Ga and the laser light source 81 (40a) adjacent to the laser light source 81 (40a) in the Y-axis direction will be described as an example, and the light propagation portion Pa provided in the light guide plate 41 will be described in detail.
　図１４は、光源群４０Ｇａに備えられた隣接するレーザ光源８０，８１から出射して光入射端面４１ｅａから導光板４１に入射するレーザ光線８０ｐ，８１ｐの光路を概念的に示した概念図である。図１５は、Ｘ軸方向の光学距離をＸとしたときに光伝播部Ｐａを伝播したレーザ光線８０ｐ，８１ｐのＹ軸方向における１次元輝度分布８０ｑ，８１ｑおよびそれらを足し合わせて生成される線状の光の１次元輝度分布８２ｑを示すグラフである。 FIG. 14 is a conceptual diagram conceptually showing optical paths of laser beams 80p and 81p that are emitted from adjacent laser light sources 80 and 81 provided in the light source group 40Ga and are incident on the light guide plate 41 from the light incident end face 41ea. . FIG. 15 shows one- dimensional luminance distributions 80q and 81q in the Y-axis direction of the laser beams 80p and 81p propagated through the light propagation portion Pa when the optical distance in the X-axis direction is X, and lines generated by adding them together. It is a graph which shows the one-dimensional luminance distribution 82q of light of a shape.
　図１４に示すように、レーザ光源８０，８１は、Ｙ軸方向に各々の発光点間の距離ｄを隔てて隣り合い、導光板４１の光入射端面４１ｅａに対向して配置されている。レーザ光源８０およびレーザ光源８１の発光面と光入射端面４１ｅａとの間隔は距離ｆに設定されている。レーザ光源８０，８１は互いに同様の特性を有しており、これらから出射されるレーザ光線８０ｐ，８１ｐのＸ－Ｙ平面における半値半角αの略ガウシアン形状の角度輝度分布は、互いに同様の形状を有している。ここで、半値半角とは、レーザビームの光強度分布において光強度がピーク値の半分となる点に対応するビーム発散角（半角）をいう。 As shown in FIG. 14, the laser light sources 80 and 81 are adjacent to each other with a distance d between the respective light emitting points in the Y-axis direction, and are disposed so as to face the light incident end face 41ea of the light guide plate 41. The distance between the light emitting surfaces of the laser light source 80 and the laser light source 81 and the light incident end surface 41ea is set to a distance f. The laser light sources 80 and 81 have the same characteristics as each other, and the angular luminance distributions of the substantially Gaussian shape having a half-value half-angle α in the XY plane of the laser beams 80p and 81p emitted from them have the same shape. Have. Here, the half value half angle means a beam divergence angle (half angle) corresponding to a point at which the light intensity is half the peak value in the light intensity distribution of the laser beam.
　レーザ光源８０，８１から出射されたレーザ光線８０ｐ，８１ｐは、光入射端面４１ｅａから導光板４１の内部に入射し、光伝播部Ｐａを伝播する。このとき、光伝播部Ｐａが有するＸ軸方向の光学距離Ｘは次式（１）で定義される。
Figure JPOXMLDOC01-appb-M000001
 Laser beams 80p and 81p emitted from the laser light sources 80 and 81 enter the light guide plate 41 from the light incident end face 41ea and propagate through the light propagation portion Pa. At this time, the optical distance X in the X-axis direction of the light propagation part Pa is defined by the following equation (1).
Figure JPOXMLDOC01-appb-M000001
　式（１）において、ｄは、レーザ光源８０，８１の発光点間距離、ｆは、レーザ光源８０，８１の出射面と光入射端面４１ｅａとの距離、αは、レーザ光源８０，８１から出射される光のＸ－Ｙ平面における発散角の半値半角、βは、導光板４１内を伝播するレーザ光線８０ｐ，８１ｐのＸ－Ｙ平面における発散角の半値半角である。 In Expression (1), d is the distance between the light emitting points of the laser light sources 80 and 81, f is the distance between the emission surface of the laser light sources 80 and 81 and the light incident end face 41ea, and α is emitted from the laser light sources 80 and 81. The half-value half-angle of the divergence angle in the XY plane of the emitted light, β is the half-value half-angle of the divergence angle in the XY plane of the laser beams 80p and 81p propagating in the light guide plate 41.
　但し、導光板４１内の半値半角βは、次式（２）で定義される。
Figure JPOXMLDOC01-appb-M000002
 However, the half value half angle β in the light guide plate 41 is defined by the following equation (2).
Figure JPOXMLDOC01-appb-M000002
　式（２）において、レーザ光源８０，８１から出射されたレーザ光線８０ｐ，８１ｐが導光板４１ａに入射する前に伝播する層の屈折率をｎ１、導光板４１の屈折率をｎ２とする。ここで、レーザ光源８０，８１の発光面積は、レーザ光源８０，８１の発光点間の距離ｄに対し十分に小さいため、その大きさを無視している。 In Expression (2), the refractive index of the layer that propagates before the laser beams 80p and 81p emitted from the laser light sources 80 and 81 enter the light guide plate 41a is n 1 , and the refractive index of the light guide plate 41 is n 2 . . Here, since the light emission areas of the laser light sources 80 and 81 are sufficiently small with respect to the distance d between the light emission points of the laser light sources 80 and 81, the size is ignored.
　上記式（１）および式（２）は、レーザ光線８０ｐとレーザ光線８１ｐとが、Ｙ軸方向の輝度分布において、それぞれのＸ軸方向の光軸８０ａ，８１ａ上に存在するピーク輝度の半分の輝度を有する位置で交点をもつために必要な光学距離Ｘを定めるものである。 In the above formulas (1) and (2), the laser beam 80p and the laser beam 81p are half the peak luminance existing on the optical axes 80a and 81a in the X axis direction in the luminance distribution in the Y axis direction. The optical distance X necessary for having an intersection at a position having luminance is determined.
　レーザ光線８０ｐおよびレーザ光線８１ｐは互いに同様の角度輝度分布を有し、各々自らの光軸８０ａ，８１ａに対称な角度輝度分布を有するため、式（１）、式（２）で定められる光学距離Ｘを伝播すると、図１５に示すように、レーザ光線８０ｐ，８１ｐがそれぞれピーク輝度Ｌを有する点（Ｙ＝ｙ０，ｙ１）の中間点（Ｙ＝ｙ２）において輝度Ｌ／２が得られる。それらのレーザ光線８０ｐ，８１ｐが重なり合うことによって中間点（Ｙ＝ｙ２）の輝度はＬとなる。従来であれば、レーザ光線８０ｐ，８１ｐの光軸８０ａ，８１ａ上に存在する明るい部分である明部に対し、レーザ光線８０ｐの光軸８０ａとレーザ光線８１ｐの光軸８１ａとの間に存在する暗い部分である暗部が存在するため、Ｙ軸方向に輝度分布むらが発生していた。しかし、式（１）、式（２）で定義される光学距離Ｘを設けることにより、レーザ光線８０ｐ，８１ｐによる明部（Ｙ＝ｙ０，ｙ１）の間にそれらと等しい輝度を有する明部（Ｙ＝ｙ２）を補うことができる。また、同時にそれらの明部（Ｙ＝ｙ０，ｙ１）間の輝度分布が平均化されるため、高い均一性を有した線状の光を生成することが可能となる。 Since the laser beam 80p and the laser beam 81p have the same angular luminance distribution and symmetrical angular distributions with respect to their own optical axes 80a and 81a, the optical distance determined by the equations (1) and (2). When propagating X, as shown in FIG. 15, the luminance L / 2 is obtained at the intermediate point (Y = y2) of the points (Y = y0, y1) where the laser beams 80p and 81p have the peak luminance L, respectively. Since the laser beams 80p and 81p overlap with each other, the luminance of the intermediate point (Y = y2) becomes L. Conventionally, a bright portion which is a bright portion existing on the optical axes 80a and 81a of the laser beams 80p and 81p exists between the optical axis 80a of the laser beam 80p and the optical axis 81a of the laser beam 81p. Since there is a dark part which is a dark part, uneven luminance distribution occurs in the Y-axis direction. However, by providing the optical distance X defined by the expressions (1) and (2), the bright part (Y = y0, y1) having the same brightness as the bright part (Y = y0, y1) by the laser beams 80p and 81p Y = y2) can be supplemented. At the same time, since the luminance distribution between these bright portions (Y = y0, y1) is averaged, it becomes possible to generate linear light with high uniformity.
　上記のように、レーザ光線８０ｐ，８１ｐが、式（１）および式（２）で定義される光学距離Ｘを有する光伝播部Ｐａを伝播することにより、光伝播部Ｐａの大きさを最小限に抑えながらもＹ軸方向の輝度分布が均一な線状の光を生成することが可能となる。 As described above, the laser beams 80p and 81p propagate through the light propagation part Pa having the optical distance X defined by the expressions (1) and (2), thereby minimizing the size of the light propagation part Pa. It is possible to generate linear light with a uniform luminance distribution in the Y-axis direction while suppressing the amount of light.
　微細光学素子４１ｄは、光伝播部Ｐａの＋Ｘ軸方向の端部から導光板４１の＋Ｘ軸方向の端部までの領域に設けられ、その配置密度は＋Ｘ軸方向に向けて疎から密に連続的に変化するよう形成されている。微細光学素子４１ｄの構造、特性については上述した通りである。 The micro optical element 41d is provided in a region from the end in the + X-axis direction of the light propagation portion Pa to the end in the + X-axis direction of the light guide plate 41, and the arrangement density is sparsely and densely continuous in the + X-axis direction. It is formed so as to change. The structure and characteristics of the micro optical element 41d are as described above.
　光源８０，８１から出射され、Ｘ軸方向の長さを光学距離Ｘとしたときの光伝播部Ｐａを伝播した光線ＩＬｅは、Ｙ軸方向である光源８０，８１の配列方向に均一な線状の光となった後、光学素子部Ｒａに入射し、面内輝度分布の均一な面状の光（照明光ＤＬａ）となって液晶表示素子１０を照明する。 The light beam ILe emitted from the light sources 80 and 81 and propagated through the light propagation portion Pa when the length in the X-axis direction is an optical distance X is linear in the arrangement direction of the light sources 80 and 81 in the Y-axis direction. Then, the light is incident on the optical element portion Ra, and illuminates the liquid crystal display element 10 as planar light (illumination light DLa) having a uniform in-plane luminance distribution.
　ここでは、導光板４１に関して記述したが、導光板４２についても同様に、式（１）、（２）を満たす光伝播部Ｐｂを備え、光線ＩＬｆは、高い均一性を有した線状の光となって微細光学素子４２ｄが形成されている光学素子部Ｒｂに入射され、面内輝度分布の均一な面状の光（照明光ＤＬｂ）となって液晶表示素子１０を照明する。 Although the light guide plate 41 has been described here, the light guide plate 42 is similarly provided with a light propagation part Pb that satisfies the expressions (1) and (2), and the light beam ILf is a linear light with high uniformity. Is incident on the optical element portion Rb in which the fine optical element 42d is formed, and illuminates the liquid crystal display element 10 as planar light (illumination light DLb) having a uniform in-plane luminance distribution.
　このような導光板４１と導光板４２とをそれぞれ有する面状光源４００ａ，４００ｂは、高い均一性の面内輝度分布を有する面状光源である。これら面状光源４００ａ，４００ｂにより作り出される照明光では、輝度分布むらが抑えられている。従って、表示むらが抑えられた高画質な液晶表示装置１０３を提供することが可能となる。 The planar light sources 400a and 400b each having the light guide plate 41 and the light guide plate 42 are planar light sources having a highly uniform in-plane luminance distribution. In the illumination light produced by these planar light sources 400a and 400b, the luminance distribution unevenness is suppressed. Therefore, it is possible to provide the high-quality liquid crystal display device 103 in which display unevenness is suppressed.
　上述のように、光伝播部Ｐａ，ＰｂのＸ軸方向の長さを上式（１）および上式（２）で定義される光学距離Ｘとすることで、高い均一性の面内輝度分布を有する面状光源を生成することが可能である。なお、この光学距離を上式（１）および上式（２）で定義されるＸより長く取ることにより、輝度分布の均一性をさらに向上させることも可能である。以上が導光板４１，４２に関する構成および動作の具体例である。 As described above, by setting the length in the X-axis direction of the light propagation portions Pa and Pb to the optical distance X defined by the above formulas (1) and (2), a highly uniform in-plane luminance distribution. It is possible to generate a planar light source having Note that the uniformity of the luminance distribution can be further improved by taking this optical distance longer than X defined by the above formulas (1) and (2). The above is a specific example of the configuration and operation related to the light guide plates 41 and 42.
　本実施の形態においては、点光源であるレーザ光源から出射したレーザ光線を線状のレーザ光に変換するために必要とされる領域の光伝播部Ｐａ，Ｐｂを、有効画像表示領域に対応する領域内に設けることができる。これにより、レーザ光線が伝播する十分な光学距離を確保しながらも、面状の光源部の周辺に光伝播部を設ける必要が無いため、液晶表示装置１０３の画像表示平面（Ｘ－Ｙ平面）の面積に対するバックライト装置９の面積の比率を小さくすることが可能となる。つまり、良好な画質の画像を提供しながらも、画像表示部分を囲むキャビネット部分であるベゼルの幅を細くした液晶表示装置１０３を実現することが可能となる。また、導光板の厚みで光伝播部を設計しているため、液晶表示装置１０３の薄型化も可能となる。 In the present embodiment, the light propagation portions Pa and Pb in an area required for converting a laser beam emitted from a laser light source that is a point light source into a linear laser beam correspond to an effective image display area. It can be provided in the region. Accordingly, it is not necessary to provide a light propagation part around the planar light source part while securing a sufficient optical distance for the laser beam to propagate, so that the image display plane (XY plane) of the liquid crystal display device 103 is obtained. It is possible to reduce the ratio of the area of the backlight device 9 to that area. That is, it is possible to realize the liquid crystal display device 103 in which the width of the bezel that is the cabinet portion surrounding the image display portion is narrowed while providing an image with good image quality. Further, since the light propagation part is designed with the thickness of the light guide plate, the liquid crystal display device 103 can be thinned.
　以上に説明したように、実施の形態３の液晶表示装置１０３によれば、レーザ光線が自ら有する発散角により近接する他のレーザ光線と空間的に重なり合い線状のレーザ光となるために必要な伝播距離である光学距離を十分に設けることが可能となるため、面内輝度分布が均一な照明光を生成することが可能となる。従って、点光源でかつ指向性の高いレーザ光源をサイドライト方式あるいはエッジライト方式の光源に採用した場合においても、輝度分布むらを抑えた良好な画像を表示できる液晶表示装置を提供することができる。 As described above, according to the liquid crystal display device 103 of the third embodiment, the laser beam is necessary to spatially overlap with other laser beams that are closer to each other due to the divergence angle that the laser beam itself has to form a linear laser beam. Since a sufficient optical distance as a propagation distance can be provided, illumination light with a uniform in-plane luminance distribution can be generated. Therefore, even when a point light source and a highly directional laser light source are employed as a side light type or edge light type light source, a liquid crystal display device capable of displaying a good image with reduced luminance distribution can be provided. .
　さらに、本実施の形態は、液晶表示装置１０３の有効画像表示領域を有効に活用して簡易な構成を実現し、この構成を、液晶表示装置１０３の有効画像表示領域に対しバックライトユニット５Ｃを大型化することなく実現することを可能にしている。また、本実施の形態においては、光伝播部Ｐａおよび光学素子部Ｒａは単一の導光板４１に設けられ、光伝播部Ｐｂおよび光学素子部Ｒｂも単一の導光板４２に設けられている。よって、光伝播部および光学素子部を個別の導光板で構成し、これらを組み合わせて使用する場合と比較して、光の損失が少なく、光利用効率が向上するとともに、部品点数が削減され組立て性が向上する。 Furthermore, in the present embodiment, a simple configuration is realized by effectively using the effective image display area of the liquid crystal display device 103, and the backlight unit 5 </ b> C is provided for the effective image display area of the liquid crystal display device 103. It can be realized without increasing the size. In the present embodiment, the light propagation part Pa and the optical element part Ra are provided on the single light guide plate 41, and the light propagation part Pb and the optical element part Rb are also provided on the single light guide plate 42. . Therefore, the light propagation part and the optical element part are composed of individual light guide plates, and compared with the case where they are used in combination, there is less light loss, the light utilization efficiency is improved, and the number of parts is reduced and assembled. Improves.
　上記のように、面状光源４００ａ，４００ｂを構成する光源としてレーザ光源を採用することは、純色性の高い色を表示し、また低消費電力駆動を実現する。さらにはその指向性の高さにより導光板４１，４２への光結合効率を向上させ、導光板４１，４２の薄型化も可能となる。 As described above, adopting a laser light source as the light source constituting the planar light sources 400a and 400b displays a color with high pure color and realizes low power consumption driving. Furthermore, the light coupling efficiency to the light guide plates 41 and 42 is improved by the high directivity, and the light guide plates 41 and 42 can be thinned.
　本実施の形態においては、複数の面状光源４００ａ，４００ｂに同様の特性を有するものを採用したが、本発明はこれに限るものでは無い。前述したように、実施の形態３は、複数の面状光源３０１，４００ａ，４００ｂから出射される照明光をＸ－Ｙ平面において足し合わせることにより面内輝度分布が均一な照明光を実現する。これを達成するのであれば、複数の面状光源から出射する照明光の面内輝度分布が異なるものであっても構わない。 In the present embodiment, the plurality of planar light sources 400a and 400b having the same characteristics are employed, but the present invention is not limited to this. As described above, the third embodiment realizes illumination light having a uniform in-plane luminance distribution by adding together illumination light emitted from the plurality of planar light sources 301, 400a, and 400b in the XY plane. As long as this is achieved, the in-plane luminance distribution of illumination light emitted from a plurality of planar light sources may be different.
　また、本実施の形態においては、レーザ光源を備える２組の面状光源４００ａ，４００ｂを積層する構成としたが、本発明はこの構成に限るものではない。上記理由と同様に、複数の面状光源が出射する照明光をＸ－Ｙ平面で足し合わせることにより、液晶表示素子１０の全体を均一に照明する照明光が生成される構成であれば、２組以上の面状光源を積層した構成としても良い。 In the present embodiment, the two sets of planar light sources 400a and 400b including a laser light source are stacked. However, the present invention is not limited to this configuration. For the same reason as above, if the illumination light emitted from a plurality of planar light sources is added together on the XY plane, the illumination light that uniformly illuminates the entire liquid crystal display element 10 is generated. It is good also as a structure which laminated | stacked the planar light source more than a group.
　上記したように、複数の面状光源から出射される照明光をＸ－Ｙ平面方向において足し合わせることにより面内輝度分布が均一なバックライトユニットを実現する構成であれば、各面状光源の面内輝度分布が如何なるものであっても良い。また、２組以上の面状光源を積層する構成としてもよいが、その際に各面状光源が有する導光板は、必ず、光入射端面の近傍に光伝播部を設ける構成とすることが望ましい。この光伝播部は、レーザ光源から出射された光線が、隣接する他のレーザ光源から出射された光線と空間的に重なり合い、レーザ光源の配列方向において輝度分布が均一となるために必要な光学距離を有している。また、光伝播部は、微細光学素子等を有さず、レーザ光線は、光伝播部内を全反射しながら伝播する。このため、微細光学素子が形成された光学素子部に伝播したレーザ光線は線状の光となっている。このため、微細光学素子により屈折し、導光板の表面から液晶表示素子１０の背面１０ｂに向かって出射される照明光の輝度分布むらが抑えられる。従って、表示むらの少ない高画質な液晶表示装置を提供することが可能となる。 As described above, the illumination light emitted from a plurality of planar light sources can be combined in the XY plane direction to achieve a backlight unit with a uniform in-plane luminance distribution. Any in-plane luminance distribution may be used. In addition, two or more sets of planar light sources may be stacked. However, in this case, the light guide plate included in each planar light source is preferably configured so that a light propagation portion is provided in the vicinity of the light incident end surface. . This light propagation part is an optical distance required for the light emitted from the laser light source to spatially overlap with the light emitted from the other adjacent laser light sources, and the luminance distribution becomes uniform in the arrangement direction of the laser light sources. have. Further, the light propagation part does not have a fine optical element or the like, and the laser beam propagates while being totally reflected in the light propagation part. For this reason, the laser beam propagated to the optical element portion on which the fine optical element is formed is linear light. For this reason, uneven brightness distribution of illumination light that is refracted by the micro optical element and emitted from the surface of the light guide plate toward the back surface 10b of the liquid crystal display element 10 is suppressed. Therefore, a high-quality liquid crystal display device with little display unevenness can be provided.
　上記構成を満足すれば、光源の配置間隔や導光板の光入射端面に対する配置方向、角度等のレーザ光源の配置方法に制限はない。また、レーザ光源を導光板４辺の何れの端面に対向して配置させる構成としてもよい。このとき、レーザ光源の光入射端面を、液晶表示素子１０の短辺側の端面とすることにより、レーザ光線の光学距離を効率良く長くすることが可能となるため、より面内輝度分布の均一性に優れた照明光を得ることが容易となる。 As long as the above configuration is satisfied, there are no restrictions on the laser light source arrangement method, such as the arrangement interval of light sources, the arrangement direction and angle of the light guide plate with respect to the light incident end face. Moreover, it is good also as a structure which arrange | positions a laser light source facing either end surface of the light-guide plate 4 sides. At this time, since the light incident end face of the laser light source is the end face on the short side of the liquid crystal display element 10, the optical distance of the laser beam can be increased efficiently, and the in-plane luminance distribution is more uniform. It becomes easy to obtain illumination light with excellent properties.
　また、本実施の形態によると、レーザ光源が導光板内の十分に長い光学距離を多重反射しながら伝播すること、また複数のレーザ光源を空間的に重ね合わせて用いることにより、従来、コヒーレンスが高いレーザ光源を用いた画像表示装置で問題となるスペックルノイズ（光の相互干渉により観測面に現れるランダムな斑点状の模様）が低減されるといった効果も得られる。 Further, according to the present embodiment, the laser light source propagates a sufficiently long optical distance in the light guide plate while performing multiple reflections, and a plurality of laser light sources are used in a spatially overlapping manner. There is also an effect that speckle noise (random spot-like pattern appearing on the observation surface due to mutual interference of light), which is a problem in an image display device using a high laser light source, is reduced.
　また、上記したようにバックライトユニット５Ｃは、光源群３２Ｇａ，３２Ｇｂ、導光板３１および蛍光体シート３８を有する。光源群３２Ｇａ，３２Ｇｂは、導光板３１のＸ軸方向の両端面の光入射端面３１ｅａ，３１ｅｂにそれぞれ対向して配置され、光源群３２Ｇａ，３２Ｇｂから出射された光線は、導光板３１の両端面の光入射端面３１ｅａ，３１ｅｂから中心方向に向かって入射する。光源群３２Ｇａ，３２Ｇｂは、図８に示されるように、青色でランバート分布の角度強度分布を有する青色光線を出射する複数個のＬＥＤ光源３０ａ，…，３０ａが一定の間隔でＹ軸方向に配列されている。導光板３１に入射した光は、実施の形態２と同様の構造を有する導光板３１の表面に設けられる微細光学素子３１ｄ，…，３１ｄで内面全反射されて、導光板３１の裏面３１ｂから蛍光体シート３８に向かって出射する青色の面状の光である照明光に変換される。 Further, as described above, the backlight unit 5C includes the light source groups 32Ga and 32Gb, the light guide plate 31, and the phosphor sheet 38. The light source groups 32Ga and 32Gb are disposed so as to oppose the light incident end surfaces 31ea and 31eb on both end surfaces in the X-axis direction of the light guide plate 31, and the light beams emitted from the light source groups 32Ga and 32Gb are both end surfaces of the light guide plate 31. From the light incident end faces 31ea and 31eb. As shown in FIG. 8, the light source group 32Ga, 32Gb includes a plurality of LED light sources 30a,..., 30a that emit blue light having a blue Lambertian angular intensity distribution arranged in the Y-axis direction at regular intervals. Has been. The light incident on the light guide plate 31 is totally reflected on the inner surface by the micro optical elements 31d,..., 31d provided on the surface of the light guide plate 31 having the same structure as that of the second embodiment, and fluorescent from the back surface 31b of the light guide plate 31. It is converted into illumination light that is blue planar light emitted toward the body sheet 38.
　上述のとおり、導光板３１から後方に出射する照明光の一部が蛍光体３７の励起光に用いられるので、蛍光体シート３８が緑色の光を放射する。一方、残った青色の照明光は、蛍光体シート３８の表面に配置された蛍光体３７、あるいは、蛍光体シート３８の背面に配置された光拡散反射シート３６で＋Ｚ軸方向に拡散して反射される。第１の面状の光である青色の照明光および第２の面状の光である緑色の照明光は混色して青緑色の照明光となって液晶表示素子１０に向けて出射される。 As described above, since a part of the illumination light emitted backward from the light guide plate 31 is used for the excitation light of the phosphor 37, the phosphor sheet 38 emits green light. On the other hand, the remaining blue illumination light is diffused and reflected in the + Z-axis direction by the phosphor 37 disposed on the surface of the phosphor sheet 38 or the light diffusion reflection sheet 36 disposed on the back surface of the phosphor sheet 38. Is done. The blue illumination light that is the first planar light and the green illumination light that is the second planar light are mixed and emitted as blue-green illumination light toward the liquid crystal display element 10.
　上記実施の形態３の面状光源３０１によれば、実施の形態２の面状光源３００と同様に、励起光である青色の光を緑色の光に効率良く変換することができるとともに、蛍光体の温度上昇による信頼性の低下および発光効率の低下を抑制することができる。 According to the planar light source 301 of the third embodiment, similarly to the planar light source 300 of the second embodiment, the blue light as the excitation light can be efficiently converted into green light, and the phosphor It is possible to suppress a decrease in reliability and a decrease in light emission efficiency due to the temperature rise.
　先にも記述した通り、導光板３１の＋Ｚ軸方向側に積層される導光板４１，４２は、透明部材で形成された板状部材の裏面に同じく透明部材で形成される微細光学素子４１ｄ，４２ｄを有する構造を有する。このため、導光板３１の前面から出射される青緑色の照明光は、導光板４１，４２を透過する際、吸収、反射などの光学的影響を受け難い。従って、導光板３１の前面から照射される青緑色の照明光の光損失は抑制され、液晶表示素子１０を照明する照明光として効率良く利用される。 As described above, the light guide plates 41 and 42 laminated on the + Z-axis direction side of the light guide plate 31 are the micro optical elements 41d, which are also formed of the transparent member on the back surface of the plate member formed of the transparent member. 42d. For this reason, the blue-green illumination light emitted from the front surface of the light guide plate 31 is less susceptible to optical influences such as absorption and reflection when passing through the light guide plates 41 and 42. Therefore, the light loss of blue-green illumination light irradiated from the front surface of the light guide plate 31 is suppressed, and the light is efficiently used as illumination light for illuminating the liquid crystal display element 10.
　青緑色の照明光と、導光板４１，４２から出射される赤色の照明光ＤＬａ，ＤＬｂとは混色して白色の照明光を形成する。光源群３２Ｇａ，３２Ｇｂは、たとえば、４５０ｎｍ付近にピークを有する青色の光線を出射する光源で構成される。この青色の光線の一部は５３０ｎｍ付近にピークを持つ蛍光体シート３８の蛍光体３７を励起する光として用いられるとともに液晶表示素子１０を照明する青色の照明光としても用いられる。青緑色の照明光を生成するための光源群３２Ｇａ，３２Ｇｂおよび蛍光体シート３８は、たとえば、光源群３２Ｇａ，３２Ｇｂを励起光源とし、蛍光体シート３８の蛍光体３７で青色および緑色を発光する構成を採用することもできる。 The blue-green illumination light and the red illumination lights DLa and DLb emitted from the light guide plates 41 and 42 are mixed to form white illumination light. The light source groups 32Ga and 32Gb are composed of light sources that emit blue light having a peak near 450 nm, for example. A part of the blue light beam is used as light for exciting the phosphor 37 of the phosphor sheet 38 having a peak near 530 nm and also used as blue illumination light for illuminating the liquid crystal display element 10. For example, the light source groups 32Ga and 32Gb and the phosphor sheet 38 for generating blue-green illumination light use the light source groups 32Ga and 32Gb as excitation light sources, and the phosphor 37 of the phosphor sheet 38 emits blue and green light. Can also be adopted.
　上述のように、実施の形態３の液晶表示装置１０３によると、光源として単色性に優れたレーザ光源、ＬＥＤおよび単色の蛍光体を採用することにより、色再現範囲の広い色鮮やかな画像を提供することができる。実施の形態３においては、特に色差に対する人間の感度が最も高い赤色の光源には色純度が非常に高いレーザを採用した。直接発光するＬＥＤやレーザでは緑色の発光効率が低い。そこで、緑色の光源には発光効率の高い蛍光体を採用した。また、青色の光源には発光効率の高いＬＥＤを採用することにより、低消費電力ながらも鮮やかな色彩表現が可能な液晶表示装置が得られる。 As described above, according to the liquid crystal display device 103 of the third embodiment, a colorful image with a wide color reproduction range is provided by adopting a laser light source, an LED, and a monochromatic phosphor excellent in monochromaticity as a light source. can do. In the third embodiment, a laser having a very high color purity is employed as a red light source that has the highest human sensitivity to color differences. Direct emission LEDs and lasers have low green emission efficiency. Therefore, a phosphor with high luminous efficiency was adopted as the green light source. In addition, by adopting an LED with high luminous efficiency as the blue light source, a liquid crystal display device capable of vivid color expression with low power consumption can be obtained.
　さらに、本実施の形態の液晶表示装置１０３は、光の指向性が異なる各光源に対しそれぞれに最適に光を拡散する光学構造を備えているので、輝度分布むらを抑えた画像を提供することが可能となる。より詳しく説明すれば、指向性を有する光を発するＬＥＤを含む光源群３２Ｇａ，３２Ｇｂから発せられた光は、導光板３１の厚みと蛍光体シート３８の光拡散反射構造とにより拡散される。ＬＥＤより指向性の高いレーザ光源を含む光源群４０Ｇａ，４０Ｇｂから発せられた光は、有効画像表示領域の約半分の光学距離を有した光伝播部Ｐａ，Ｐｂにより拡散される。上記構成により、液晶表示装置１０３を大型化することなく、指向性を有した光を十分に拡散し、輝度分布むらを抑える高画質な画像表示を行う液晶表示装置を実現している。 Furthermore, the liquid crystal display device 103 according to the present embodiment includes an optical structure that optimally diffuses light for each light source having different light directivities, and thus provides an image with reduced luminance distribution unevenness. Is possible. More specifically, light emitted from the light source groups 32Ga and 32Gb including LEDs that emit light having directivity is diffused by the thickness of the light guide plate 31 and the light diffusion reflection structure of the phosphor sheet 38. Light emitted from the light source groups 40Ga and 40Gb including a laser light source having higher directivity than the LED is diffused by the light propagation portions Pa and Pb having an optical distance about half of the effective image display area. With the above configuration, a liquid crystal display device that realizes high-quality image display that sufficiently diffuses directional light and suppresses uneven luminance distribution is realized without increasing the size of the liquid crystal display device 103.
　実施の形態３によれば、たとえば、制御部により各光源駆動部を個別に制御して、導光板４１，４２から出射される赤色の照明光ＤＬａ，ＤＬｂの輝度と、導光板３１から出射される青緑色の照明光の輝度との割合を調整することができる。このため、映像信号に対し必要となる各色輝度の割合に応じて各面状光源の発光量を調整することにより、低消費電力化を実現することも可能である。また、蛍光体シート３８が出射する緑色の光の強さは、青緑色の照明光の強さに対して、Ｚ軸方向の蛍光体３７の厚み、あるいはＸ－Ｙ平面に対する微細光学素子３１ｄの空間的な粗密で調整される。 According to the third embodiment, for example, the light source driving unit is individually controlled by the control unit, and the luminance of the red illumination lights DLa and DLb emitted from the light guide plates 41 and 42 and the light guide plate 31 are emitted. The ratio of the brightness of the blue-green illumination light can be adjusted. For this reason, it is also possible to realize low power consumption by adjusting the light emission amount of each planar light source in accordance with the ratio of each color luminance required for the video signal. Further, the intensity of the green light emitted from the phosphor sheet 38 is the thickness of the phosphor 37 in the Z-axis direction or the fine optical element 31d with respect to the XY plane relative to the intensity of the blue-green illumination light. Spatial density is adjusted.
　実施の形態３のように、複数の面状光源３０１，４００ａ，４００ｂのうち、輝度の高い緑色の光を含む面状光源３０１を液晶表示素子１０から最も遠い位置に配置している。この配置は、迷光の影響を抑えることで、迷光が原因となる輝度分布むらを抑えて、液晶表示素子１０の表示むらの低減およびコントラストの向上を図るものである。 As in the third embodiment, among the plurality of planar light sources 301, 400a, and 400b, the planar light source 301 including green light with high luminance is disposed at a position farthest from the liquid crystal display element 10. This arrangement suppresses the influence of stray light, thereby suppressing the uneven luminance distribution caused by the stray light, thereby reducing the display unevenness of the liquid crystal display element 10 and improving the contrast.
　また、緑色の光を発する面状光源３０１を最も液晶表示素子１０から遠い位置に配置することで、迷光により面状光源の中に輝度の高い部分があった場合でも、他の導光板４１，４２や微細光学素子４１ｄ，４２ｄを透過する際の光の屈折等による拡散および発散により輝度分布むらが低減する。また、照明光が液晶表示素子１０に到達するまでの一定の距離があるため、光の発散角によっても輝度分布むらが抑えられる。なお、迷光とは正規の反射や屈折以外の原因の内面反射により生じる望ましくない光のことである。 Further, by arranging the planar light source 301 that emits green light at a position farthest from the liquid crystal display element 10, even when there is a portion with high luminance in the planar light source due to stray light, the other light guide plates 41, 42 and the fine optical elements 41d and 42d, unevenness in luminance distribution is reduced by diffusion and divergence due to light refraction and the like. In addition, since there is a certain distance until the illumination light reaches the liquid crystal display element 10, unevenness in luminance distribution can be suppressed by the divergence angle of the light. Note that stray light is undesirable light generated by internal reflection due to causes other than normal reflection and refraction.
　従来の光源は蛍光ランプを用いているが、液晶表示素子１０が有するカラーフィルタの透過波長を狭く設定し色純度を高める場合には、蛍光ランプを用いるとカラーフィルタによる光の損失が増加して画像の輝度が低下してしまう。一方、実施の形態３では、レーザ光源、ＬＥＤ光源および蛍光体の単色性を高めて色純度を向上させているので、光の損失は減少し、明るさの低下を抑え、低消費電力で、色純度を高めることができる。 The conventional light source uses a fluorescent lamp. However, when the transmission wavelength of the color filter of the liquid crystal display element 10 is set narrow to increase the color purity, the use of the fluorescent lamp increases the light loss due to the color filter. The brightness of the image decreases. On the other hand, in Embodiment 3, since the color purity is improved by improving the monochromaticity of the laser light source, the LED light source and the phosphor, the loss of light is reduced, the decrease in brightness is suppressed, and the power consumption is reduced. Color purity can be increased.
　実施の形態３における、複数の面状光源３０１，４００ａ，４００ｂを積層して構成されるバックライトユニット５Ｃは、その＋Ｚ軸方向側の上層側に備えられる導光板４１，４２や、これら導光板４１，４２に設けられる微細光学素子４１ｄ，４２ｄが何れも透明部材で構成されている。このため、それらより－Ｚ軸方向側の下層側に配置される導光板３１の前面から出射される照明光は、上層側の導光板４１，４２の背面に入射するが、当該照明光は上層側の導光板４１，４２や微細光学素子４１ｄ，４２ｄを透過するため、下層側からの照明光の損失を抑え、高い光利用効率を得ることが可能である。 The backlight unit 5C configured by laminating a plurality of planar light sources 301, 400a, and 400b in Embodiment 3 includes light guide plates 41 and 42 provided on the upper layer side of the + Z axis direction side, and these light guide plates. The micro optical elements 41d and 42d provided on 41 and 42 are both made of a transparent member. For this reason, the illumination light emitted from the front surface of the light guide plate 31 disposed on the lower layer side on the −Z-axis direction side is incident on the rear surfaces of the upper light guide plates 41 and 42, but the illumination light is incident on the upper layer. Since the light guide plates 41 and 42 on the side and the fine optical elements 41d and 42d are transmitted, it is possible to suppress a loss of illumination light from the lower layer side and obtain high light use efficiency.
　なお、実施の形態３においては、光源群４０Ｇａ，４０Ｇｂを構成する光源４０ａ，４０ｂに６４０ｎｍにピーク波長を有する赤色のレーザ光源を採用したが、本発明はこれに限るものではない。たとえば、波長の異なる赤色のレーザ光線や、あるいは青色、緑色の可視単色光を出射するレーザ光源を採用してもよい。このときには、導光板３１の前面から出射される照明光の色は、それらレーザ光源の発光色と補色の関係を成す色を有するよう構成する。 In the third embodiment, a red laser light source having a peak wavelength of 640 nm is used for the light sources 40a and 40b constituting the light source groups 40Ga and 40Gb. However, the present invention is not limited to this. For example, you may employ | adopt the laser light source which radiate | emits red laser beam from which a wavelength differs, or blue and green visible monochromatic light. At this time, the color of the illumination light emitted from the front surface of the light guide plate 31 is configured to have a color that is complementary to the emission color of the laser light source.
実施の形態４．
　図１６は、本発明に係る実施の形態４の透過型表示装置である液晶表示装置１０４の構成を模式的に示す構成図である。実施の形態１の液晶表示装置１０１は、光学シート１２を備えたのに対し、実施の形態４の液晶表示装置１０４は、光学シート１２を備えないところが異なる。図１６において、実施の形態１で説明した液晶表示装置１０１の構成要素と同様の構成要素には、同一符号を付し、その説明を省略する。 Embodiment 4 FIG.
FIG. 16 is a configuration diagram schematically showing a configuration of a liquid crystal display device 104 which is a transmissive display device according to the fourth embodiment of the present invention. The liquid crystal display device 101 according to the first embodiment includes the optical sheet 12, whereas the liquid crystal display device 104 according to the fourth embodiment differs in that the optical sheet 12 is not provided. In FIG. 16, the same components as those of the liquid crystal display device 101 described in Embodiment 1 are denoted by the same reference numerals, and the description thereof is omitted.
　図１６に示されるように、液晶表示装置１０４は、透過型の液晶表示素子１０と、第１の光学シートである光学シート１１と、バックライトユニット５Ａを備えており、これら構成要素１０，１１，５Ａは、Ｚ軸方向に積層して配列されている。本実施の形態のバックライトユニット５Ａは、光源群２０Ｇａ，２０Ｇｂと導光板２１と光拡散反射シート２６とから構成されている。よって、本実施の形態のバックライトユニット５Ａは、実施の形態１のバックライトユニット５Ａと同じである。 As shown in FIG. 16, the liquid crystal display device 104 includes a transmissive liquid crystal display element 10, an optical sheet 11 that is a first optical sheet, and a backlight unit 5 </ b> A. , 5A are stacked in the Z-axis direction. The backlight unit 5A of the present embodiment is composed of light source groups 20Ga and 20Gb, a light guide plate 21, and a light diffusion reflection sheet 26. Therefore, the backlight unit 5A of the present embodiment is the same as the backlight unit 5A of the first embodiment.
　上記実施の形態１の液晶表示装置１０１が備える光学シート１２の主な機能は、バックライトユニットから出射される照明光の輝度分布むらを抑制することである。従来の液晶表示装置においては、輝度分布むらを抑制することを目的として光学シートが備えられることが一般的である。これに対し、実施の形態４の液晶表示装置１０４は、光学シート１２を備えない。これは、本実施の形態のバックライトユニット５Ａが、従来のバックライトユニットと比較して面内の空間輝度分布の均一性に優れた面状の光を出射することが可能なためである。 The main function of the optical sheet 12 provided in the liquid crystal display device 101 of the first embodiment is to suppress uneven luminance distribution of illumination light emitted from the backlight unit. In a conventional liquid crystal display device, an optical sheet is generally provided for the purpose of suppressing uneven luminance distribution. On the other hand, the liquid crystal display device 104 of the fourth embodiment does not include the optical sheet 12. This is because the backlight unit 5A of the present embodiment can emit planar light with excellent uniformity of in-plane spatial luminance distribution as compared with the conventional backlight unit.
　バックライトユニット５Ａから空間輝度分布の均一性に優れた面状の光が出射可能であることは、先にも説明した通り、以下の理由による。バックライトユニット５Ａにおいて、光源群２０Ｇａ，２０Ｇｂから出射した光線ＩＬａ，ＩＬｂは面状の照明光ＢＬａ，ＢＬｂとなって導光板２１の裏面２１ｂから、この導光板２１の背面（液晶表示素子１０と反対側、－Ｚ軸方向）側に備えられる光拡散反射シート２６へと向けて出射される。照明光ＢＬａ，ＢＬｂは、光拡散反射シート２６で拡散して反射し、＋Ｚ軸方向に向かう照明光となり、導光板２１を透過して導光板２１表面から出射される。＋Ｚ軸方向に進行する照明光ＢＬａ，ＢＬｂは、導光板２１の表面から出射する際、導光板２１に備えられる微細光学素子２１ｄ，…，２１ｄの屈折作用によりさらに拡散する。そのため、光源群２０Ｇａ，２０Ｇｂから出射した光線ＩＬａ，ＩＬｂは、導光板２１の表面から出射するまでに、少なくとも導光板の厚みの２倍に相当する光学距離を伝播することになる。従って、導光板２１の表面から出射するまでに、光線が自らの発散角により拡散するための光学距離をバックライトユニット５Ａの大きさを抑えながら確保することができる。 The planar light having excellent uniformity of spatial luminance distribution can be emitted from the backlight unit 5A for the following reason as described above. In the backlight unit 5A, the light beams ILa and ILb emitted from the light source groups 20Ga and 20Gb become planar illumination lights BLa and BLb from the back surface 21b of the light guide plate 21 to the back surface of the light guide plate 21 (with the liquid crystal display element 10). The light is emitted toward the light diffusing and reflecting sheet 26 provided on the opposite side (the −Z-axis direction) side. The illumination lights BLa and BLb are diffused and reflected by the light diffusion reflection sheet 26 to become illumination light directed in the + Z-axis direction, pass through the light guide plate 21 and are emitted from the surface of the light guide plate 21. When the illumination lights BLa and BLb traveling in the + Z-axis direction are emitted from the surface of the light guide plate 21, they are further diffused by the refracting action of the micro optical elements 21d,. Therefore, the light beams ILa and ILb emitted from the light source groups 20Ga and 20Gb propagate an optical distance corresponding to at least twice the thickness of the light guide plate before being emitted from the surface of the light guide plate 21. Therefore, it is possible to ensure an optical distance for the light beam to diffuse by its own divergence angle while suppressing the size of the backlight unit 5 </ b> A before being emitted from the surface of the light guide plate 21.
　また、光線ＩＬａ，ＩＬｂは、微細光学素子２１ｄ，…，２１ｄの光学作用により面状の光である照明光ＢＬａ，ＢＬｂとなる。照明光ＢＬａ，ＢＬｂは、導光板２１の表面から出射するまでの光路中において光拡散反射シート２６により拡散して反射する。この光拡散作用により、導光板２１の光入射端近傍やその他の位置においても、照明光ＢＬａ，ＢＬｂは、Ｘ－Ｙ平面において拡散し空間的に重なり合った後に導光板２１の表面から出射される。また、上述のように照明光ＢＬａ，ＢＬｂが導光板２１の表面から出射する際、微細光学素子２１ｄ，…，２１ｄの屈折作用によりさらに拡散する。これらの拡散作用により、バックライトユニット５Ａから出射される照明光ＢＬａ，ＢＬｂの面内輝度分布は優れた均一性を有する。 Further, the light beams ILa and ILb become illumination lights BLa and BLb which are planar lights by the optical action of the micro optical elements 21d,. The illumination lights BLa and BLb are diffused and reflected by the light diffusion reflection sheet 26 in the optical path from the surface of the light guide plate 21 until it is emitted. Due to this light diffusion action, the illumination lights BLa and BLb are emitted from the surface of the light guide plate 21 after being diffused and spatially overlapped in the XY plane even in the vicinity of the light incident end of the light guide plate 21 and other positions. . Further, as described above, when the illumination lights BLa and BLb are emitted from the surface of the light guide plate 21, they are further diffused by the refractive action of the micro optical elements 21d,. Due to these diffusing actions, the in-plane luminance distribution of the illumination lights BLa and BLb emitted from the backlight unit 5A has excellent uniformity.
　従って、実施の形態４の液晶表示装置１０４においては、面状の光の面内輝度分布の均一性を高めるため備えられる光学シート１２を必要とすることなく、輝度むらのない画像を提供することが可能となる。よって、部品点数を削減し、コストの低減や組み立て行程の簡易化などの効果を得ることができる。 Therefore, in the liquid crystal display device 104 of the fourth embodiment, an image without luminance unevenness is provided without the need for the optical sheet 12 provided to improve the uniformity of the in-plane luminance distribution of planar light. Is possible. Therefore, the number of parts can be reduced, and effects such as cost reduction and simplification of the assembly process can be obtained.
　本実施の形態の液晶表示装置１０４においては、上記光拡散作用を得るための構造が画像の表示面１０ｆの法線方向、つまり、表示面１０ｆの面と垂直な方向に沿って設けられている。また、導光板２１の厚みと光の反射光路を利用してバックライトユニット５Ａの厚み方向に光が拡散するための光路が効率良く設けられている。このため、バックライトユニット５Ａは、液晶表示素子１０の表示面１０ｆの面内方向（Ｘ－Ｙ面の面内方向）において大型化することなく、画像表示部分を囲むキャビネット部分であるベゼルの幅を細くしたデザインを可能とし、また、バックライトユニット５Ａから出射される照明光の輝度分布むらを抑制することが可能となる。 In the liquid crystal display device 104 of the present embodiment, the structure for obtaining the light diffusing action is provided along the normal direction of the image display surface 10f, that is, the direction perpendicular to the surface of the display surface 10f. . In addition, an optical path for efficiently diffusing light in the thickness direction of the backlight unit 5A is efficiently provided using the thickness of the light guide plate 21 and the light reflection optical path. For this reason, the backlight unit 5A is not enlarged in the in-plane direction of the display surface 10f of the liquid crystal display element 10 (the in-plane direction of the XY plane), and the width of the bezel that is the cabinet portion surrounding the image display portion. It is possible to make the design thinner, and it is possible to suppress uneven brightness distribution of illumination light emitted from the backlight unit 5A.
　以上に説明したように実施の形態４の液晶表示装置１０４は、光学シート１２を必要とすることなく、簡易で且つ小型な構成にて、輝度分布むらを抑えた高画質な画像を提供することが可能となる。 As described above, the liquid crystal display device 104 according to the fourth embodiment provides a high-quality image with reduced luminance distribution with a simple and small configuration without the need for the optical sheet 12. Is possible.
実施の形態５．
　次に、本発明に係る実施の形態５について説明する。実施の形態５は、実施の形態４の構成を実施の形態２に対して適用したものである。図１７は、実施の形態５の液晶表示装置１０５の構成を模式的に示す構成図である。上記実施の形態２の液晶表示装置１０２は、光学シート１２を備えたのに対し、実施の形態５の液晶表示装置１０５は、光学シート１２を備えないところが異なる。図１７において、実施の形態２で説明した液晶表示装置１０２の構成要素と同様の構成要素には、同一符号を付し、その説明を省略する。 Embodiment 5 FIG.
Next, a fifth embodiment according to the present invention will be described. In the fifth embodiment, the configuration of the fourth embodiment is applied to the second embodiment. FIG. 17 is a configuration diagram schematically showing the configuration of the liquid crystal display device 105 of the fifth embodiment. The liquid crystal display device 102 of the second embodiment is provided with the optical sheet 12, whereas the liquid crystal display device 105 of the fifth embodiment is different in that the optical sheet 12 is not provided. In FIG. 17, the same components as those of the liquid crystal display device 102 described in the second embodiment are denoted by the same reference numerals, and the description thereof is omitted.
　図１７に示されるように、液晶表示装置１０５は、透過型の液晶表示素子１０と、第１の光学シートである光学シート１１と、バックライトユニット５Ｂとを備えており、これら構成要素１０，１１，５Ｂは、Ｚ軸方向に積層して配列されている。バックライトユニット５Ｂは、光源群３２Ｇａ，３２Ｇｂと、導光板３１と、緑色の光を発する蛍光体３７を光拡散反射シート３６に塗布した蛍光体シート３８とから構成されている。つまり、蛍光体シート３８は光拡散反射シート３６と蛍光体３７とから構成されている。光源群３２Ｇａ，３２Ｇｂは、青色の単色光を出射するＬＥＤと赤色の単色光を出射するＬＥＤとがＹ軸方向に一定の間隔で交互に配列されている。蛍光体シート３８は青色のＬＥＤの光を吸収し緑色の光を発する。よって、本実施の形態のバックライトユニット５Ｂは、上記実施の形態２のバックライトユニット５Ｂと同じである。 As shown in FIG. 17, the liquid crystal display device 105 includes a transmissive liquid crystal display element 10, an optical sheet 11 that is a first optical sheet, and a backlight unit 5B. 11 and 5B are stacked and arranged in the Z-axis direction. The backlight unit 5B includes light source groups 32Ga and 32Gb, a light guide plate 31, and a phosphor sheet 38 in which a phosphor 37 that emits green light is applied to a light diffusion reflection sheet 36. That is, the phosphor sheet 38 is composed of the light diffuse reflection sheet 36 and the phosphor 37. In the light source groups 32Ga and 32Gb, LEDs that emit blue monochromatic light and LEDs that emit red monochromatic light are alternately arranged at regular intervals in the Y-axis direction. The phosphor sheet 38 absorbs blue LED light and emits green light. Therefore, the backlight unit 5B of the present embodiment is the same as the backlight unit 5B of the second embodiment.
　本実施の形態の導光板３１は、上述した実施の形態２の導光板３１と同様の構造を有する。従って、導光板３１は、光源群３２Ｇａ，３２Ｇｂから出射された光線ＩＬｃ，ＩＬｄに対して同様に作用する。光源群３２Ｇａ，３２Ｇｂから出射された光線ＩＬｃ，ＩＬｄは、導光板３１内を伝播する。その際、赤色の光と青色の光は混ざり合い、光線ＩＬｃ，ＩＬｄは混色した光線となる。光線ＩＬｃ，ＩＬｄは、導光板３１の＋Ｚ軸方向の面に形成された微細光学素子３１ｄ，…，３１ｄにより－Ｚ軸方向に向かう照明光ＢＬｃ，ＢＬｄに変換される。照明光ＢＬｃ，ＢＬｄは、青色の光線ＢＬと赤色の光線ＲＬとが混色した第１の面状の光である。照明光ＢＬｃ，ＢＬｄは、導光板３１の－Ｚ軸方向側の面３１ｂから蛍光体シート３８に向けて出射される。 The light guide plate 31 of the present embodiment has the same structure as the light guide plate 31 of the second embodiment described above. Therefore, the light guide plate 31 similarly acts on the light beams ILc and ILd emitted from the light source groups 32Ga and 32Gb. Light beams ILc and ILd emitted from the light source groups 32Ga and 32Gb propagate through the light guide plate 31. At that time, the red light and the blue light are mixed, and the light beams ILc and ILd are mixed light beams. The light beams ILc and ILd are converted into illumination lights BLc and BLd directed in the −Z axis direction by the micro optical elements 31d,..., 31d formed on the surface of the light guide plate 31 in the + Z axis direction. The illumination lights BLc and BLd are first planar light in which the blue light beam BL and the red light beam RL are mixed. The illumination lights BLc and BLd are emitted toward the phosphor sheet 38 from the surface 31b of the light guide plate 31 on the −Z axis direction side.
　蛍光体シート３８に向けて出射された照明光ＢＬｃ，ＢＬｄは、その青色の光線ＢＬの一部が蛍光体シート３８を構成する蛍光体３７の励起光として用いられ、蛍光体シート３８から緑色の照明光ＦＬが出射される。この緑色の照明光ＦＬは第２の面状の光である。なお、励起光とは、蛍光体３７の励起に用いられる光である。 In the illumination lights BLc and BLd emitted toward the phosphor sheet 38, a part of the blue light beam BL is used as excitation light of the phosphor 37 constituting the phosphor sheet 38, and the green color from the phosphor sheet 38 is increased. Illumination light FL is emitted. The green illumination light FL is second planar light. The excitation light is light used for exciting the phosphor 37.
　照明光ＢＬｃ，ＢＬｄは、蛍光体シート３８の＋Ｚ軸方向側に配置された蛍光体３７の表面または蛍光体シート３８の－Ｚ軸方向側に配置された光拡散反射シート３６で拡散して反射される。この反射した照明光ＢＬｃ，ＢＬｄは、蛍光体３７の励起に用いられなかった青色の光線ＢＬと赤色の光線ＲＬとが混色した光となり、第１の面状の光（照明光ＢＬｃ，ＢＬｄ）として蛍光体シート３８から＋Ｚ軸方向に出射する。この青色の光線ＢＬと赤色の光線ＲＬとからなる第１の面状の光（照明光ＢＬｃ，ＢＬｄ）は、蛍光体シート３８の蛍光体３７から出射した緑色の第２の面状の光（照明光ＦＬ）と混ざり、白色の照明光となり＋Ｚ軸方向に出射される。蛍光体シート３８の蛍光体３７から出射する光線ＦＬのうち－Ｚ軸方向に出射された光線は、光拡散反射シート３６で＋Ｚ軸方向に拡散して反射される。 The illumination lights BLc and BLd are diffused and reflected by the surface of the phosphor 37 arranged on the + Z axis direction side of the phosphor sheet 38 or the light diffusion reflection sheet 36 arranged on the −Z axis direction side of the phosphor sheet 38. Is done. The reflected illumination lights BLc and BLd are mixed light of the blue light beam BL and the red light beam RL that are not used for exciting the phosphor 37, and the first planar light (illumination light BLc and BLd). Is emitted from the phosphor sheet 38 in the + Z-axis direction. The first planar light (illumination light BLc, BLd) composed of the blue light beam BL and the red light beam RL is a second green planar light beam emitted from the phosphor 37 of the phosphor sheet 38 ( Is mixed with the illumination light FL) and becomes white illumination light, which is emitted in the + Z-axis direction. Of the light beam FL emitted from the phosphor 37 of the phosphor sheet 38, the light beam emitted in the −Z-axis direction is diffused and reflected by the light diffusion reflection sheet 36 in the + Z-axis direction.
　実施の形態５の液晶表示装置１０５によれば、青色および赤色の光線は、導光板３１から－Ｚ軸方向に出射され、蛍光体シート３８の蛍光体３７の表面もしくは光拡散反射シート３６の反射面で拡散して反射されて、再び導光板３１に戻ってくる。当該光線は、液晶表示素子１０の画像表示面１０ｆの法線方向に沿って設けられた光路を往復して伝播し、蛍光体シート３８で拡散されることから、バックライトユニット５Ｂから出射される照明光の面内輝度分布は優れた均一性を有する。 According to the liquid crystal display device 105 of the fifth embodiment, the blue and red light beams are emitted from the light guide plate 31 in the −Z-axis direction and reflected from the surface of the phosphor 37 of the phosphor sheet 38 or the light diffusion reflection sheet 36. The light is diffused and reflected by the surface, and returns to the light guide plate 31 again. The light beam travels back and forth along the optical path provided along the normal direction of the image display surface 10f of the liquid crystal display element 10, and is diffused by the phosphor sheet 38, and thus is emitted from the backlight unit 5B. The in-plane luminance distribution of the illumination light has excellent uniformity.
　また、蛍光体３７から放射される緑色の光は指向性を有さないため、例え不均一な青色の光が蛍光体３７に入射した場合であっても、照明光ＦＬは面内輝度分布が均一な緑色の面状の光となって蛍光体３７から出射される。この青色と赤色とからなる第１の面状の光（照明光ＢＬｃ，ＢＬｄ）と緑色の第２の面状の光（照明光ＦＬ）とが混色して、面内輝度分布が均一な白色の第３の面状の光（照明光ＭＬ）となり液晶表示素子１０を照明する。従って、実施の形態５の液晶表示装置１０５は、簡易で小型な構成により、輝度分布むらを抑えた良好な画像を提供することができる。 Further, since the green light emitted from the phosphor 37 has no directivity, the illumination light FL has an in-plane luminance distribution even when non-uniform blue light is incident on the phosphor 37. The light is emitted from the phosphor 37 as uniform green planar light. The first planar light (illumination light BLc, BLd) composed of blue and red and the green second planar light (illumination light FL) are mixed to produce a white color with a uniform in-plane luminance distribution. The third planar light (illumination light ML) is used to illuminate the liquid crystal display element 10. Therefore, the liquid crystal display device 105 of Embodiment 5 can provide a good image with reduced luminance distribution with a simple and small configuration.
　実施の形態５の液晶表示装置１０５においては、上記光拡散作用を得るための構造が画像の表示面１０ｆの法線方向、つまり、表示面１０ｆの面と垂直な方向に沿って設けられている。また、導光板３１の厚みと光の反射光路を利用してバックライトユニット５Ｂの厚み方向に光が拡散するための光路が効率良く設けられている。このため、バックライトユニット５Ｂが液晶表示素子１０の表示面１０ｆの面内方向（Ｘ－Ｙ面の面内方向）において大型化することなく、画像表示部分を囲むキャビネット部分であるベゼルの幅を細くしたデザインを可能とし、また、バックライトユニット５Ｂから出射される照明光の輝度分布むらを抑制することが可能となる。 In the liquid crystal display device 105 of the fifth embodiment, the structure for obtaining the light diffusing action is provided along the normal direction of the image display surface 10f, that is, the direction perpendicular to the surface of the display surface 10f. . Further, an optical path for efficiently diffusing light in the thickness direction of the backlight unit 5B is efficiently provided by using the thickness of the light guide plate 31 and the light reflection optical path. For this reason, the backlight unit 5B does not increase in size in the in-plane direction of the display surface 10f of the liquid crystal display element 10 (in the in-plane direction of the XY plane), and the width of the bezel that is the cabinet portion surrounding the image display portion is increased. It is possible to make the design thinner, and to suppress uneven brightness distribution of illumination light emitted from the backlight unit 5B.
　以上に説明したように実施の形態５の液晶表示装置１０５は、光学シート１２を必要とすることなく、簡易で且つ小型な構成にて、輝度分布むらを抑えた高画質な画像を提供することが可能となる。 As described above, the liquid crystal display device 105 according to the fifth embodiment provides a high-quality image with reduced luminance distribution with a simple and small configuration without the need for the optical sheet 12. Is possible.
　以上、図面を参照して本発明に係る種々の実施の形態について述べた。上記実施の形態１～５は、面内輝度分布が均一な照明光を生成するバックライトユニット（面光源装置）および液晶表示装置について有用であり、輝度分布むらを抑えて信頼性を向上した液晶表示装置を実現することができる。 The various embodiments according to the present invention have been described above with reference to the drawings. The first to fifth embodiments are useful for a backlight unit (surface light source device) and a liquid crystal display device that generate illumination light with a uniform in-plane luminance distribution, and a liquid crystal with improved reliability by suppressing uneven luminance distribution. A display device can be realized.
　上述の実施の形態１～５において、「平行」や「垂直」などの部品間の位置関係もしくは部品の形状を示す用語を用いているが、これらは、製造上の公差や組立て上のばらつきなどを考慮した範囲を含むものである。このため、請求の範囲に例え「略」を記載しない場合であっても製造上の公差や組立て上のばらつきなどを考慮した範囲を含むものである。 In the first to fifth embodiments described above, terms such as “parallel” and “vertical” indicating the positional relationship between the parts or the shape of the parts are used. These are, for example, manufacturing tolerances and assembly variations. It includes the range that takes into account. For this reason, even if “abbreviation” is not described in the claims, it includes a range that takes into account manufacturing tolerances and assembly variations.
　１０　液晶表示素子、　１０ｆ　表示面、　５Ａ，５Ｂ，５Ｃ　バックライトユニット、　２０，３０，４０ａ，４０ｂ　光源、　２１，３１，４１，４２　導光板、　ＩＬａ，ＩＬｂ，３４，４４　光線、　２１ｅａ，２１ｅｂ，３１ｅａ，３１ｅｂ，４１ｅａ，４２ｅｂ　光入射端面、　２１ｄ，３１ｄ，４１ｄ，４２ｄ　微細光学素子、　Ｐａ，Ｐｂ　光伝播部、　ＢＬａ，ＢＬｂ，ＢＬｃ，ＢＬｄ，ＦＬ，ＭＬ，ＤＬａ，ＤＬｂ　照明光、　Ｒａ，Ｒｂ　光学素子部、　３６　光拡散反射シート、　３７　蛍光体、　３８　蛍光体シート、　１０１，１０２，１０３，１０４，１０５　液晶表示装置。 10 liquid crystal display element, 10f display surface, 5A, 5B, 5C backlight unit, 20, 30, 40a, 40b light source, 21, 31, 41, 42 light guide plate, ILa, ILb, 34, 44 light beam, 21ea, 21eb, 31ea, 31eb, 41ea, 42eb Light incident end face, 21d, 31d, 41d, 42d fine optical element, Pa, Pb light propagation part, BLa, BLb, BLc, BLd, FL, ML, DLa, DLb illumination light, Ra, Rb Optical element part, 36 light diffuse reflection sheet, 37 phosphor, 38 phosphor sheet, 101, 102, 103, 104, 105 liquid crystal display device.

Claims (20)

  1. 　複数の第１の光線をそれぞれ出射する複数の第１の光源と、
    　前記複数の第１の光線が入射する光入射端面を有するとともに複数の第１の光学素子が形成された前面を有する第１の導光板と、
    　前記第１の導光板の裏面と対向するように配置される反射部材と
    を備え、
    　前記複数の第１の光学素子は、前記光入射端面に入射した当該複数の第１の光線を前記反射部材の方向に内面反射させて面状光を生成し、
    　前記反射部材は、前記第１の導光板の前記裏面から放射された当該面状光を前記第１の導光板の方向に反射させ、
    　前記第１の導光板は、前記反射部材から入射した当該面状光を透過させて前記前面から第１の照明光として放射する
    ことを特徴とする面光源装置。     A plurality of first light sources that respectively emit a plurality of first light rays;
    A first light guide plate having a light incident end face on which the plurality of first light beams are incident and having a front surface on which a plurality of first optical elements are formed;
    A reflective member disposed so as to face the back surface of the first light guide plate,
    The plurality of first optical elements generate planar light by internally reflecting the plurality of first light rays incident on the light incident end surface in a direction of the reflecting member,
    The reflection member reflects the planar light emitted from the back surface of the first light guide plate in the direction of the first light guide plate,
    The surface light source device, wherein the first light guide plate transmits the planar light incident from the reflection member and emits the first illumination light from the front surface.
  2. 　前記反射部材は、前記第１の導光板の当該裏面から入射した当該面状光を拡散反射させる請求項１に記載の面光源装置。 The surface light source device according to claim 1, wherein the reflecting member diffusely reflects the planar light incident from the back surface of the first light guide plate.
  3. 　前記反射部材は、
    　前記第１の導光板の当該裏面から入射した当該面状光の一部を前記第１の導光板の方向に反射させる光反射面と、
    　前記光反射面上に配置された蛍光体と
    を有し、
    　前記蛍光体は、前記第１の導光板の当該裏面から入射した当該面状光の他の一部で励起されて第２の照明光を放射し、
    　前記第１の導光板は、前記反射部材から入射した前記第２の照明光を前記第１の照明光に混ぜて放射する
    請求項１または２に記載の面光源装置。     The reflective member is
    A light reflecting surface that reflects part of the planar light incident from the back surface of the first light guide plate in the direction of the first light guide plate;
    A phosphor disposed on the light reflecting surface;
    The phosphor is excited by another part of the planar light incident from the back surface of the first light guide plate and emits second illumination light,
    3. The surface light source device according to claim 1, wherein the first light guide plate radiates the second illumination light incident from the reflecting member by mixing the first illumination light with the first illumination light.
  4. 　前記第２の照明光は、前記第１の照明光のピーク波長と補色の関係にあるピーク波長を有する請求項３に記載の面光源装置。 4. The surface light source device according to claim 3, wherein the second illumination light has a peak wavelength that is complementary to a peak wavelength of the first illumination light.
  5. 　前記第２の照明光は、緑色のピーク波長の光を含む請求項４に記載の面光源装置。 The surface light source device according to claim 4, wherein the second illumination light includes light having a green peak wavelength.
  6. 　複数の第２の光線をそれぞれ出射する複数の第２の光源と、
    　前記第１の導光板よりも前方に配置され、前記複数の第２の光線が入射する光入射端面を有するとともに複数の第２の光学素子が形成された裏面を有する第２の導光板と
    をさらに備え、
    　前記複数の第２の光学素子は、前記第２の導光板の当該光入射端面に入射した当該複数の第２の光線を内面反射させて面状の第３の照明光を生成し、
    　前記第２の導光板は、前記第１の導光板から入射した光を透過させ且つ前記第３の照明光に混ぜて放射する
    請求項３から５のうちのいずれか１項に記載の面光源装置。     A plurality of second light sources that respectively emit a plurality of second light rays;
    A second light guide plate disposed in front of the first light guide plate, having a light incident end face on which the plurality of second light beams are incident and having a back surface on which a plurality of second optical elements are formed. In addition,
    The plurality of second optical elements reflect the plurality of second light rays incident on the light incident end face of the second light guide plate to generate a third illumination light having a planar shape,
    6. The surface light source according to claim 3, wherein the second light guide plate transmits the light incident from the first light guide plate and emits the light mixed with the third illumination light. 7. apparatus.
  7. 　前記第２の導光板は、前記第２の導光板の当該光入射端面から所定距離の範囲内に前記第２の光学素子が形成されない領域に対応する光伝播部を有し、
    　前記光伝播部は、前記第２の導光板の当該光入射端面に入射した当該複数の第２の光線のうち少なくとも隣接する光線を空間的に重ね合わせる光学距離を有する
    請求項６に記載の面光源装置。     The second light guide plate has a light propagation part corresponding to a region where the second optical element is not formed within a predetermined distance from the light incident end surface of the second light guide plate,
    The surface according to claim 6, wherein the light propagation part has an optical distance for spatially overlapping at least adjacent light beams among the plurality of second light beams incident on the light incident end surface of the second light guide plate. Light source device.
  8. 　前記複数の第２の光源は、前記第２の導光板の当該光入射端面に沿って一列に配列されている請求項７に記載の面光源装置。 The surface light source device according to claim 7, wherein the plurality of second light sources are arranged in a line along the light incident end face of the second light guide plate.
  9. 　前記第２の光線と同じ色を持つ複数の第３の光線をそれぞれ出射する複数の第３の光源と、
    　前記第２の導光板よりも前方に配置され、前記複数の第３の光線が入射する光入射端面を有するとともに複数の第３の光学素子が形成された裏面を有する第３の導光板と
    をさらに備え、
    　前記複数の第３の光学素子は、前記第３の導光板の当該光入射端面に入射した当該複数の第３の光線を内面反射させて面状の第４の照明光を生成し、
    　前記第３の導光板は、前記第２の導光板から入射した光を透過させ且つ前記第４の照明光に混ぜて放射し、
    　前記第３の導光板は、前記第３の導光板の当該光入射端面から所定距離の範囲内に前記第３の光学素子が形成されない領域に対応する光伝播部を有し、
    　前記第３の導光板の当該光伝播部は、前記第３の導光板の当該光入射端面に入射した当該複数の第３の光線のうち少なくとも隣接する光線を空間的に重ね合わせる光学距離を有する
    請求項７または８に記載の面光源装置。     A plurality of third light sources that respectively emit a plurality of third light rays having the same color as the second light rays;
    A third light guide plate disposed in front of the second light guide plate, having a light incident end face on which the plurality of third light beams are incident and having a back surface on which a plurality of third optical elements are formed. In addition,
    The plurality of third optical elements are configured to internally reflect the plurality of third light beams incident on the light incident end surface of the third light guide plate to generate planar fourth illumination light,
    The third light guide plate transmits the light incident from the second light guide plate and radiates mixed with the fourth illumination light,
    The third light guide plate has a light propagation part corresponding to a region where the third optical element is not formed within a predetermined distance from the light incident end surface of the third light guide plate,
    The light propagation portion of the third light guide plate has an optical distance for spatially overlapping at least adjacent light rays among the plurality of third light rays incident on the light incident end face of the third light guide plate. The surface light source device according to claim 7 or 8.
  10. 　前記複数の第３の光源は、前記第３の導光板の当該光入射端面に沿って一列に配列されている請求項９に記載の面光源装置。 The surface light source device according to claim 9, wherein the plurality of third light sources are arranged in a line along the light incident end face of the third light guide plate.
  11. 　前記第２の導光板の当該光伝播部は、前記第１乃至第３の導光板の配列方向に対して垂直な所定方向の端部側に形成されており、
    　前記第３の導光板の当該光伝播部は、前記所定方向とは反対方向の端部側に形成されている
    請求項９または１０に記載の面光源装置。     The light propagation part of the second light guide plate is formed on the end side in a predetermined direction perpendicular to the arrangement direction of the first to third light guide plates,
    11. The surface light source device according to claim 9, wherein the light propagation portion of the third light guide plate is formed on an end portion side opposite to the predetermined direction.
  12. 　前記第３の照明光と前記第４の照明光とは空間的に重ね合わさることにより略均一な光強度分布を有する照明光を形成する請求項９から１１のうちのいずれか１項に記載の面光源装置。 12. The illumination light according to claim 9, wherein the third illumination light and the fourth illumination light are spatially superimposed to form illumination light having a substantially uniform light intensity distribution. Surface light source device.
  13. 　前記第３の照明光の色は、前記第１の照明光と前記第２の照明光とが混ざった光の色に対して補色である請求項６から１２のうちのいずれか１項に記載の面光源装置。 The color of the third illumination light is a complementary color with respect to the color of light in which the first illumination light and the second illumination light are mixed. Surface light source device.
  14. 　前記第２の光線は、赤色のピーク波長を有する請求項６から１３のうちのいずれか１項に記載の面光源装置。 14. The surface light source device according to claim 6, wherein the second light beam has a red peak wavelength.
  15. 　前記第２の光源は、可視単色光を出射するレーザ光源である請求項６から１４のうちのいずれか１項に記載の面光源装置。 The surface light source device according to any one of claims 6 to 14, wherein the second light source is a laser light source that emits visible monochromatic light.
  16. 　前記第１の光源は、前記第２の光源の発光色とは異なる色の可視光を出射する発光ダイオードである請求項６から１５のうちのいずれか１項に記載の面光源装置。 The surface light source device according to any one of claims 6 to 15, wherein the first light source is a light emitting diode that emits visible light having a color different from an emission color of the second light source.
  17. 　前記複数の第１の光源は、白色発光ダイオードからなる請求項１または２に記載の面光源装置。 The surface light source device according to claim 1 or 2, wherein the plurality of first light sources are formed of white light emitting diodes.
  18. 　前記複数の第１の光源は、前記蛍光体の発光色とは異なり且つ互いに異なる色の可視光をそれぞれ出射する２種類の発光ダイオードからなる請求項３から５のうちのいずれか１項に記載の面光源装置。 6. The light emitting diode according to claim 3, wherein each of the plurality of first light sources includes two types of light emitting diodes that emit different colors of visible light different from the emission color of the phosphor. Surface light source device.
  19. 　請求項１から１８のうちのいずれか１項に記載の面光源装置と、
    　前記面光源装置から放射された面状光の強度を空間的に変調して画像光を生成する液晶表示素子と、
    を備えたことを特徴とする液晶表示装置。     A surface light source device according to any one of claims 1 to 18,
    A liquid crystal display element that spatially modulates the intensity of the planar light emitted from the surface light source device to generate image light;
    A liquid crystal display device comprising:
  20. 　前記面光源装置と前記液晶表示装置との間に配置された光学シートをさらに備え、
    　前記光学シートは、前記面光源装置から放射された面状光を拡散透過させる
    液晶表示装置。     An optical sheet disposed between the surface light source device and the liquid crystal display device;
    The optical sheet is a liquid crystal display device that diffuses and transmits planar light emitted from the surface light source device.
PCT/JP2011/004150 2010-08-03 2011-07-22 Surface light-source apparatus and liquid crystal display apparatus WO2012017613A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
JP2012527577A JPWO2012017613A1 (en) 2010-08-03 2011-07-22 Surface light source device and liquid crystal display device
TW100127168A TW201222098A (en) 2010-08-03 2011-08-01 Surface light source and LCD

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2010174561 2010-08-03
JP2010-174561 2010-08-03

Publications (1)

Publication Number Publication Date
WO2012017613A1 true WO2012017613A1 (en) 2012-02-09

Family

ID=45559138

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2011/004150 WO2012017613A1 (en) 2010-08-03 2011-07-22 Surface light-source apparatus and liquid crystal display apparatus

Country Status (3)

Country Link
JP (1) JPWO2012017613A1 (en)
TW (1) TW201222098A (en)
WO (1) WO2012017613A1 (en)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013161462A1 (en) * 2012-04-25 2013-10-31 東芝ライテック株式会社 Solid-state lighting device
WO2014020870A1 (en) * 2012-07-31 2014-02-06 三菱電機株式会社 Liquid crystal display
JP2015041439A (en) * 2013-08-21 2015-03-02 三菱電機株式会社 Illumination device and display device including the same
EP2871408A1 (en) * 2013-11-11 2015-05-13 LG Display Co., Ltd. Backlight unit and display device including the same
US9103950B2 (en) 2011-02-15 2015-08-11 Mitsubishi Electric Corporation Surface light source device and liquid crystal display device
CN105182606A (en) * 2015-08-18 2015-12-23 友达光电股份有限公司 Display device
WO2016093449A1 (en) * 2014-12-09 2016-06-16 Samsung Electronics Co., Ltd. Display device and backlight unit included therein
KR20160077482A (en) * 2014-12-23 2016-07-04 엘지디스플레이 주식회사 Liquid crystal display device
US9645302B2 (en) 2013-03-21 2017-05-09 Lg Display Co., Ltd. Backlight unit and display device including the same
JP2019124834A (en) * 2018-01-17 2019-07-25 株式会社ジャパンディスプレイ Display device

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008108523A (en) * 2006-10-25 2008-05-08 Seiko Instruments Inc Lighting system, and display device equipped with it
JP2008117879A (en) * 2006-11-02 2008-05-22 Harison Toshiba Lighting Corp Surface light-emitting device
JP2009076464A (en) * 2008-10-30 2009-04-09 Sharp Corp Illuminating device, and display device equipped with it
JP2009170325A (en) * 2008-01-18 2009-07-30 Minebea Co Ltd Planar lighting system
JP2010152370A (en) * 2010-01-22 2010-07-08 Panasonic Corp Liquid crystal display device

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006073202A (en) * 2004-08-31 2006-03-16 Nichia Chem Ind Ltd Light emitting device
JP5178460B2 (en) * 2008-11-04 2013-04-10 富士フイルム株式会社 Surface lighting device
CN102203645A (en) * 2008-11-05 2011-09-28 皇家飞利浦电子股份有限公司 Light emitting device

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008108523A (en) * 2006-10-25 2008-05-08 Seiko Instruments Inc Lighting system, and display device equipped with it
JP2008117879A (en) * 2006-11-02 2008-05-22 Harison Toshiba Lighting Corp Surface light-emitting device
JP2009170325A (en) * 2008-01-18 2009-07-30 Minebea Co Ltd Planar lighting system
JP2009076464A (en) * 2008-10-30 2009-04-09 Sharp Corp Illuminating device, and display device equipped with it
JP2010152370A (en) * 2010-01-22 2010-07-08 Panasonic Corp Liquid crystal display device

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9103950B2 (en) 2011-02-15 2015-08-11 Mitsubishi Electric Corporation Surface light source device and liquid crystal display device
WO2013161462A1 (en) * 2012-04-25 2013-10-31 東芝ライテック株式会社 Solid-state lighting device
WO2014020870A1 (en) * 2012-07-31 2014-02-06 三菱電機株式会社 Liquid crystal display
JP5931199B2 (en) * 2012-07-31 2016-06-08 三菱電機株式会社 Surface light source device and liquid crystal display device
US9645302B2 (en) 2013-03-21 2017-05-09 Lg Display Co., Ltd. Backlight unit and display device including the same
JP2015041439A (en) * 2013-08-21 2015-03-02 三菱電機株式会社 Illumination device and display device including the same
EP2871408A1 (en) * 2013-11-11 2015-05-13 LG Display Co., Ltd. Backlight unit and display device including the same
US10444424B2 (en) 2014-12-09 2019-10-15 Samsung Electronics Co., Ltd. Display device and backlight unit included therein
USRE48689E1 (en) 2014-12-09 2021-08-17 Samsung Electronics Co., Ltd. Display device and backlight unit included therein
WO2016093449A1 (en) * 2014-12-09 2016-06-16 Samsung Electronics Co., Ltd. Display device and backlight unit included therein
US9513427B2 (en) 2014-12-09 2016-12-06 Samsung Electronics Co., Ltd. Display device and backlight unit included therein
KR20160077482A (en) * 2014-12-23 2016-07-04 엘지디스플레이 주식회사 Liquid crystal display device
KR102298922B1 (en) * 2014-12-23 2021-09-07 엘지디스플레이 주식회사 Liquid crystal display device
CN105182606B (en) * 2015-08-18 2019-05-14 友达光电股份有限公司 Display device
CN105182606A (en) * 2015-08-18 2015-12-23 友达光电股份有限公司 Display device
JP2019124834A (en) * 2018-01-17 2019-07-25 株式会社ジャパンディスプレイ Display device

Also Published As

Publication number Publication date
JPWO2012017613A1 (en) 2013-09-19
TW201222098A (en) 2012-06-01

Similar Documents

Publication Publication Date Title
JP5523538B2 (en) Surface light source device
WO2012017613A1 (en) Surface light-source apparatus and liquid crystal display apparatus
TWI489180B (en) A planar light source device, and a liquid crystal display device
JP5460893B2 (en) Angular intensity distribution shaping member and surface light source device
US8998474B2 (en) Surface light source device and liquid crystal display apparatus
JP5940157B2 (en) Surface light source device and liquid crystal display device
TWI474085B (en) Surface light source device and liquid crystal display device
JP2011238484A (en) Backlight device and liquid crystal display
JP2011228078A (en) Backlight device and liquid crystal display device
JP2010101912A (en) Liquid crystal device
JP4356095B1 (en) Liquid crystal display device and lighting device
JP2011258458A (en) Backlight device and liquid crystal display device
JP5669210B2 (en) Display device
JP2009199832A (en) Illumination apparatus and display apparatus
JP2015138613A (en) Surface light source device and liquid crystal display device

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 11814252

Country of ref document: EP

Kind code of ref document: A1

WWE Wipo information: entry into national phase

Ref document number: 2012527577

Country of ref document: JP

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 11814252

Country of ref document: EP

Kind code of ref document: A1