JP2009157115A - Optical sheet, backlight unit, backlight device, and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a display device small in thickness, and to eliminate the luminance unevenness of a screen. <P>SOLUTION: A translucent base material 41 is disposed on an exit surface of a light guide 25, constituted so to make a light of a light source 23 emit from the entire surface of the exiting surface. The exiting surface of the translucent base material 41 is integrally provided with a plurality of optical elements 43 for condensing the light emitted from the exiting surface of the translucent base material 41. Furthermore, the incident surface of the translucent base material 41 is integrally provided with a light-shielding layer 45 for shielding the light emitted from the exiting surface of the translucent base material 41. A plurality of apertures 46, penetrating into the thickness direction of the light-shielding layer 46, are formed in the light-shielding layer 45 so as to overlap in the thickness direction of the translucent base material 41 at the optical axis of each optical element 43. Then, relating to each aperture 46 disposed to face the luminance peak region, where the luminance of the light from the light source 23 is highest at the exiting surface of the light guide 25, the opening area thereof is formed smallest. Furthermore, since the luminance becomes smaller along the incident surface of the translucent base material 41, the opening area of the aperture 46 is set larger. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical sheet, a backlight unit, a backlight device, and a display device.

The demand for thinning a display device such as a large-sized liquid crystal television is increasing year by year. However, as a conventional display device aiming for thinning, for example, as disclosed in Patent Document 1, an image display unit such as a liquid crystal panel is used. Some have a backlight unit that emits planar light. This backlight unit diffuses light from the light source in the surface direction of the image display unit and emits light from the light exiting surface on the light guide plate. A transmittance adjusting unit that adjusts the distribution, a diffusion film that diffuses the light that has passed through the transmittance adjusting unit, and a plurality of light that focuses the diffused light so as to be directed in a specific direction (for example, a normal direction to the display screen) These prism sheets are laminated.
Note that the luminance distribution in the angular direction of light emitted from the prism sheet toward the image display unit has the highest luminance of light emitted in a specific direction (for example, the visual direction of the viewer), and the angle with respect to this visual direction is large. It is desirable for the brightness to decrease smoothly.
JP 2006-318754 A

  However, in the conventional backlight unit described above, the transmittance adjusting unit, the diffusion film, and the plurality of prism sheets are laminated after being manufactured individually, so that the manufacture of the backlight unit is troublesome and the backlight unit is thinned. There is a problem that there is a limit.

  In addition, when the light diffusion in the light guide is insufficient, the light distribution of the light emitted from the emission surface may be biased, that is, the light emitted from the emission surface of the light guide. May have a light distribution in which the luminance of light rays emitted at a predetermined angle with respect to the emission surface is strong and the luminance of light rays in a direction inclined with respect to the predetermined angle is weak. Furthermore, the light distribution may vary depending on the position of the exit surface, that is, the light distribution described above may vary depending on the position of the exit surface. When such a light distribution distribution bias or variation occurs, there is a problem that the luminance distribution in the angular direction described above cannot be obtained due to an increase in the luminance of light in a direction not directed to the visual direction.

  The present invention can efficiently eliminate uneven brightness of light generated on the exit surface of a light guide and can be thinned, and further includes an optical sheet that can emit light having a brightness distribution in a desired angular direction. An object is to provide a backlight unit, a backlight device, and a display device.

In order to solve the above problems, the present invention proposes the following means.
The optical sheet of the present invention is formed in a substantially plate shape, one surface forms an emission surface that emits light from a light source, and the light guide is configured to emit the light from the entire emission surface. The optical sheet is disposed opposite to the emission surface and controls the light emitted from the emission surface, and is formed on a base material, and one surface is incident on the light from the emission surface of the light guide. A light-transmitting translucent substrate that forms an incident surface and the other surface forms a light-exiting surface, and an exit surface of the translucent substrate so as to protrude from the exit surface of the translucent substrate A plurality of optical elements that are integrally provided to collect light emitted from the emission surface of the translucent substrate, and an emission surface of the light guide that is integrally provided on the incident surface of the translucent substrate. A light shielding layer that shields light emitted from the optical element, and the light shielding layer overlaps the optical axis of each optical element and the thickness direction of the translucent substrate. A plurality of openings penetrating in the thickness direction of the light-shielding layer, and at a position facing an illuminance or luminance peak region where the illuminance or luminance of the light from the light source is highest on the exit surface of the light guide. The arranged opening is formed with the smallest opening area, and as the illuminance or luminance decreases along the incident surface of the translucent substrate, the opening area of the opening increases, The central axis of at least one opening is shifted in the direction along the optical axis of the optical element that overlaps the central axis and the emission surface of the translucent substrate.

By defining the size of the opening in this manner, the amount of light blocked in the light shielding layer can be increased as the illuminance or luminance peak region is closer to the light exit surface of the light guide. Therefore, even if the luminance distribution in the surface direction of the light on the light exit surface of the light guide is non-uniform, the light emitted from the light exit surface of the light guide passes through each opening of the light shielding layer, thereby transmitting the light. Luminance unevenness of light emitted from the emission surface of the substrate can be efficiently suppressed.
This optical sheet is configured by integrally providing a light shielding layer for suppressing luminance unevenness and an optical element for condensing light that has passed through the opening on both surfaces of the translucent substrate. By providing the optical sheet in a backlight unit or a display device, the thickness can be easily reduced.
In addition, the direction of the light emitted from the exit surface of the optical sheet can be changed by shifting the central axis of the aperture and the optical axis of the optical element overlapping the aperture in a direction along the exit surface of the translucent substrate. Can be controlled.

Specifically, in the light distribution of light incident on the incident surface of the transmissive substrate through one opening, the oblique light incident obliquely at a predetermined incident angle with respect to the transmissive substrate. When the brightness of the light becomes the highest, by setting the position of one opening as follows, the light having the highest brightness is emitted from the optical sheet in a specific direction different from the direction of the oblique light. be able to.
For example, the central axis of the one opening and the optical axis of the optical element are arranged in order along the incident surface of the translucent substrate so as to be almost opposite to the direction of the oblique light. In this case, compared to the case where the central axis and the optical axis coincide with each other, the emission surface of the translucent substrate in the optical element corresponding to the one opening portion has the direction of the oblique light having the highest luminance. It can be close to the normal direction.

Further, for example, the central axis of the one opening and the optical axis of the optical element are arranged in order along the incident surface of the translucent substrate so as to substantially match the direction of the oblique light. In this case, compared with the case where the central axis and the optical axis coincide with each other, the direction of the oblique light having the highest luminance is emitted from the translucent substrate in the optical element corresponding to one opening. Further away from the normal direction of the surface.
As described above, the position of the central axis of each opening with respect to the optical axis of each optical element is individually set, and the direction of the light emitted from the plurality of optical elements is aligned in a specific direction, so that the brightness of the optical sheet can be reduced. High light can be emitted in a specific direction. Therefore, by using this optical sheet, the luminance of the light emitted from the optical sheet is the highest in the luminance of the light emitted in a specific direction, and the luminance distribution in the angular direction becomes smaller as the angle with respect to the specific direction increases. Can be obtained.

In the optical sheet, it is preferable that the light shielding layer is formed on the incident surface of the translucent substrate by gravure printing or screen printing.
In this case, since the light shielding layer having a plurality of openings can be easily formed on the incident surface of the translucent substrate, the number of manufacturing steps of the optical sheet can be reduced and the manufacturing efficiency can be improved.
In addition, since all the openings can be positioned with respect to each optical element simply by determining the printing position of the light shielding layer, the relative positions of the openings and the optical elements that overlap each other in the thickness direction of the translucent substrate are individually set. There is no need to align. Therefore, it is possible to easily manufacture the optical sheet and reduce its manufacturing cost.

  In the optical sheet, the optical element disposed at a position where the illuminance or luminance peak region on the light exit surface of the light guide overlaps with the thickness direction of the translucent substrate is orthogonal to the optical axis. It is more preferable that the width dimension of the optical element be formed larger as the illuminance or luminance decreases along the emission surface of the translucent substrate.

  When the width dimension of the optical element is defined as described above, the light collection efficiency by the optical element increases as the illuminance or luminance decreases on the exit surface of the translucent substrate. The luminance unevenness of the light can be further reduced.

  Moreover, in the said optical sheet, it is good also considering the cross-sectional shape of the width direction of these optical elements orthogonal to the output surface of the said translucent base material as a mutually similar shape.

In the optical sheet, the cross-sectional shape in the width direction of the plurality of optical elements orthogonal to the emission surface of the translucent substrate is the illuminance or luminance peak region on the emission surface of the light guide and the transmission peak. As the inclination angle of the optical element arranged at a position overlapping the thickness direction of the light-based substrate is formed largest, and as the illuminance or luminance decreases along the emission surface of the light-transmitting substrate, The optical element may be formed so that the tilt angle of the optical element is small.
Furthermore, in the optical sheet, the height dimensions of the plurality of optical elements protruding from the emission surface of the translucent substrate may be substantially equal to each other.
In this case, it is possible to reduce the thickness of the optical sheet.

In addition, when the light source is a point light source and the illuminance or luminance peak area is an area of the exit surface of the light guide that overlaps the point light source and the thickness direction of the light guide, the optical sheet The optical element may be formed as follows.
For example, when viewed from the exit surface side of the translucent substrate, one optical element overlapping the point light source is formed in a shape centered on the point light source, and the other plurality of optical elements centered on the point light source It may be formed in a ring shape.
In addition, for example, a plurality of optical elements whose longitudinal direction is one direction along the emission surface of the translucent substrate are the one direction along the emission surface of the translucent substrate and a direction orthogonal thereto. It may be arranged.

Further, for example, when viewed from the exit surface side of the translucent substrate, one optical element overlapping the point light source is formed in a shape centered on the point light source, and the other plurality of optical elements are the one optical element. You may arrange in the direction away from an optical element.
Further, for example, when viewed from the emission surface side of the translucent substrate, the plurality of optical elements may be formed radially along the emission surface of the translucent substrate with the point light source as a center. Good.

  The light source is a rod-shaped light source extending in one direction along the exit surface of the light guide, and the illuminance or luminance peak region of the light guide overlaps with the rod-shaped light source in the thickness direction of the light guide. In the case of the region of the emission surface, for example, the plurality of optical elements are formed in a long shape extending in the one direction and are parallel to the one direction along the emission surface of the light guide. May be arranged.

Further, in the optical sheet, the optical element may be a lens having a convex curved surface.
In the optical sheet, the optical element may be a prism.

The backlight unit according to the present invention includes the optical sheet, the light source, and the light guide, and the light guide is recessed from the emission surface or the other surface on the opposite side, and the light source is provided to the light guide. An accommodating recess for accommodating is formed, an emission surface of the light guide is formed in a substantially flat surface, and the other surface is directed from a region where the accommodating recess is formed toward an end portion in the surface direction of the light guide. Therefore, the light guide is formed with an inclined surface that is inclined from the opening edge of the housing recess so that the thickness of the light guide is reduced.
In the backlight unit according to the present invention, the light from the light source can be emitted from the entire emission surface of the light guide, and the same effect as the optical sheet described above can be obtained.

In the backlight unit, a light diffusion layer in which light diffusion particles are mixed may be provided between the light guide and the optical sheet.
In the backlight unit, the light guide may be configured to include a light diffusion region in which light diffusion particles are mixed between the emission surface and the light source.

According to these backlight units, before the light from the light source is incident on the optical sheet, the light is diffused in the light diffusion region or the light diffusion layer. Luminance unevenness can be reduced. Accordingly, it is possible to further suppress the luminance unevenness of the light emitted from the emission surface of the translucent substrate.
When the light diffusion region is included in the light guide, the number of parts of the backlight unit can be reduced and the backlight unit can be made thinner.

In the backlight unit, the optical sheet and the light guide are fixed to each other, and an air layer defined by the opening is formed between the light guide and the translucent substrate. May be.
According to the backlight unit having this configuration, the thickness dimension of the backlight unit can be minimized by fixing the optical sheet and the light guide to each other. In addition, since an air layer having a refractive index lower than that of the translucent substrate is defined between the exit surface of the light guide and the incident surface of the translucent substrate, light is transmitted from the air layer. The light can be efficiently collected when entering the conductive substrate.

  In the backlight unit, the light guide may be manufactured by an injection molding method, or may be manufactured by an extrusion molding method.

The backlight device according to the present invention is characterized in that a plurality of the backlight units are connected and arranged along the emission surface of the light guide.
In the backlight device, it is more preferable that the plurality of optical sheets are integrally formed.
In the backlight device, it is more preferable that the plurality of light guides are integrally formed.

  The display device of the present invention is arranged on the light emitting surface side of the backlight unit or the backlight device and the translucent substrate, and displays light from the backlight unit or the backlight device. And an image display unit that displays an image as light.

  According to these backlight devices and display devices, the same effects as the above-described optical sheet and backlight unit can be obtained, and the screen of the display device can be easily enlarged. In addition, by integrally forming a plurality of optical sheets and light guides, it is possible to prevent optical influences such as refraction from occurring when light passes across the connecting portions of backlight units adjacent to each other. Therefore, it is possible to prevent the occurrence of luminance unevenness based on the above-described connection portion.

ADVANTAGE OF THE INVENTION According to this invention, the backlight unit and display apparatus which can aim at the thickness reduction while being able to eliminate efficiently the brightness | luminance nonuniformity of the light which arises in the output surface of a light guide can be provided.
In addition, by shifting the central axis of the opening with respect to the optical axis of the optical element, the light emitted from each optical element is emitted even if the distribution of light emitted from the light exit surface of the light guide is uneven or uneven. Since the direction of the emitted light can be controlled, light having a luminance distribution in a desired angular direction can be emitted from the optical sheet toward the image display unit.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, an optical sheet according to an embodiment of the present invention will be described together with a backlight unit, a backlight device, and a display device using the optical sheet.

As shown in FIG. 1, a display device 100 according to an embodiment of the present invention is configured by providing a liquid crystal display element (screen display unit) 13 on the upper side of a backlight device 11 that emits light upward. The liquid crystal display device displays a planar image by emitting display light whose display is controlled by an image signal from the liquid crystal display element 13 upward.
Hereinafter, based on such an arrangement, the upper direction in FIG. 1 may be simply referred to as a display screen side, and the lower direction may be simply referred to as a back side.
The display device 100 is assumed to be a liquid crystal display device including the liquid crystal display element 13. However, if the display device 100 includes at least the backlight device 11, a projection screen device, a plasma display, an EL display, or the like is used. The type of the image display unit that displays an image using the light from the backlight device 11 as display light is not limited.

The liquid crystal display element 13 is configured by sandwiching a liquid crystal 15 between two polarizing plates 17 and 19. The backlight device 11 has a light emission surface (light emitting surface) substantially the same as the display screen of the liquid crystal display element 13, and is configured by arranging a plurality of backlight units 21 along the display screen. Yes.
As shown in FIGS. 1 and 2, each backlight unit 21 includes one light source 23, a light guide 25 arranged in order on the display screen side of the light source 23, and an optical sheet 27. Has been. The light source 23 of the present embodiment is a point light source and is configured to emit light in all directions. As such a light source 23, a light emitting diode (LED) is preferable. As a light emitting diode, for example, a method of emitting white light by combining light emitting elements that emit light of a single color is well known. In mobile devices such as mobile phones, there is a white LED that emits pseudo white light by mounting a yellow phosphor on a light emitting element that emits blue light. Note that the light source 23 that is a point light source is not limited to the above-described example, but, for example, as provided in a mobile device, one monochromatic light emitting element is covered with at least one other type of phosphor, and pseudo white May emit light. Specifically, for example, as shown in FIG. 13, the light source 23 may be configured by covering a blue light emitting element 23B mounted on a substrate 23A with an LED lens 23D in which a yellow light emitting phosphor 23C is formed. . The light source 23 is not limited to an LED as long as it is a point light source, and may be a normal fluorescent lamp, a halogen lamp, a semiconductor laser, or the like.

The light guide 25 is formed in a substantially plate shape having a substantially rectangular shape in plan view, using a material having transparency. One surface of the light guide 25 forms an emission surface 25a from which light from the light source 23 is emitted, and is formed flat. Further, the light source 23 described above is arranged in the center portion in the surface direction on the other surface side of the light guide 25. That is, the light guide 25 is formed with a housing recess 29 having a substantially U-shaped cross section that is recessed from the other surface and houses the light source 23.
Then, the other surface of the light guide 25 is formed so that the thickness of the light guide 25 is reduced from the region where the housing recess 29 is formed toward the end in the surface direction of the light guide 25. An inclined surface 25b that is inclined from the opening edge is formed. That is, in this light guide 25, the vicinity region in which the housing recess 29 is formed is the thickest portion having the largest thickness, and the end portion of the light guide 25 is the thin portion having the smallest thickness.
In addition, as a concrete shape of the inclined surface 25b mentioned above, the conical surface and pyramid surface centering on the accommodation recessed part 29 are mentioned, for example. In the illustrated example, the inclined surface 25b is linearly formed from the opening edge of the housing recess 29 toward the end in the surface direction of the light guide 25. For example, FIGS. As shown in FIG. 4, it may be formed in a curved shape. Here, the curved inclined surface 25b may be formed so as to be recessed inward as shown in FIG. 3A or may be formed so as to swell as shown in FIG. Moreover, the inclined surface 25b may be formed by combining a plurality of linear flat surfaces having different inclination angles, as shown in FIG. 3C, for example. Furthermore, the inclined surface 25b may be formed by connecting a concave curved surface and a convex curved surface, for example, as shown in FIG. Furthermore, the inclined surface 25b may be formed, for example, in a shape that combines the shapes shown in FIGS. 2 and 3A to 3D.

In addition, the shape of the inclined surface 25b shown to Fig.3 (a)-(d) is an illustration, and is not limited to these shapes. For example, a combination of straight lines and curves may be used. Therefore, for example, the inclined surface 25b may be formed in a linear shape from the storage recess 29 to the vicinity of the thin portion, and may be formed in a curved shape that is recessed inward in the vicinity of the thin portion.
In addition, a prism shape or a lens shape may be formed on the inclined surface 25b. By forming the prism shape and the lens shape on the inclined surface 25b, the light incident on the inclined surface 25b can be more uniformly diffused. Therefore, the light emitted from the emission surface 25a of the light guide 25 Can be made more uniform.

As a material for forming the light guide 25, various materials can be used depending on the application as long as the material has heat resistance, mechanical strength, and solvent resistance to withstand manufacturing in addition to transparency. Specifically, for example, polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate, polyethylene terephthalate-isophthalate copolymer, terephthalic acid-cyclohexanedimethanol-ethylene glycol copolymer Polyester resins such as coextruded films of polyethylene terephthalate / polyethylene naphthalate, polyamide resins such as nylon 6, nylon 66 and nylon 610, polyolefin resins such as polyethylene, polypropylene (PP) and polymethylpentene, polyvinyl chloride Vinyl resin such as polyacrylate, polymethacrylate, acrylic resin such as polymethyl methacrylate (PMMA), polyimide, polyamideimide, polyetherimide, etc. Engineering resins such as imide resins, polyarylate, polysulfone, polyethersulfone, polyphenylene ether, polyphenylene sulfide (PPS), polyaramid, polyetherketone, polyethernitrile, polyetheretherketone, polyethersulfite, polycarbonate (PC), polystyrene, high impact polystyrene, acrylonitrile polystyrene copolymer, styrene resin such as ABS resin, cellulose film such as cellophane, cellulose triacetate, cellulose diacetate, and nitrocellulose.
And this light guide 25 is produced using, for example, a method of molding a heated raw material resin by extrusion molding or injection molding, a casting polymerization method of polymerizing and molding monomers, oligomers, etc. in a mold. Can do.

A light reflecting plate 31 is disposed on the inclined surface 25 b of the light guide 25. The light reflecting plate 31 may be fixed to the inclined surface 25b as in the illustrated example, but may be arranged so as to cover at least the inclined surface 25b. For example, a gap is provided between the light reflecting plate 31 and the inclined surface 25b. It may be arranged with a gap. In this case, it is desirable that the light reflecting plate 31 facing the inclined surface 25b is arranged so that the reflecting surface 31a is parallel to the inclined surface 25b.
This light reflecting plate 31 is a resin sheet in which a void is formed by kneading and stretching a filler in PET, PP or the like to increase the reflectance, or a sheet having a mirror surface formed by aluminum vapor deposition on the surface of a transparent or white resin sheet It can be formed of a metal foil such as aluminum, a resin sheet carrying the metal foil, or a metal thin plate having sufficient reflectivity on the surface.
Further, a reflector 33 having light reflectivity is disposed below the housing recess 29 so as to close the opening. The reflector 33 can be formed of, for example, the same material as the light reflecting plate 31, that is, a resin material, a metal foil, or a metal plate with sufficient surface reflection. Therefore, the light traveling from the light source 23 to the lower side of the housing recess 29 is reflected by the reflector 33 and then enters the light guide 25.

  With the above configuration, the light from the light source 23 enters the light guide 25 directly or after being reflected by the reflector 33. Then, the incident light passes through the inside of the light guide 25 and directly exits from the exit surface 25a of the light guide 25, or is reflected from the inclined surface 25b and then exits from the exit surface 25a. A part of the light is transmitted through the inclined surface 25b, but the transmitted light is reflected by the light reflecting plate 31 and then emitted from the emission surface 25a. That is, the light guide 25 is configured to emit the light of the light source 23 from the entire emission surface 25a.

In the light guide 25, the depth dimension and shape of the housing recess 29 described above are preferably formed so that the entire light source 23 can be housed, and the dimensions of the light source 23 and the optical characteristics of the light guide 25. It is preferable to determine in consideration of mechanical strength, aging, and the like.
As the shape of the housing recess 29, for example, as shown in FIG. 4A, it may be formed in a U shape, or as shown in FIG. 4B, its upper surface may be a flat surface. . In the case of a flat surface, the central portion of the light exit surface 25a of the light guide 25 can be brightened. Moreover, you may form in a tapered shape like FIG.4 (c)-(g), for example, In this case, the output surface 25a of the light guide 25 located just above the light source 23 can be made dark. In the case of a tapered shape, a V shape is formed as shown in FIG. 4C, a curved shape is formed inside the receiving recess as shown in FIG. 4D, and the outer side of the receiving recess is shown as FIG. 4E. It is good also as the curved surface shape which swells. Moreover, it is good also as a shape which combined several flat surfaces and curved surfaces like FIG.4 (f), (g), and the freedom degree of the light distribution on the output surface 25a of the light guide 25 improves in this case. To do. Furthermore, the accommodation recessed part 29 may be formed in the shape which combined the shape shown to FIG.4 (c)-(g), for example.
The shapes of the storage recesses 29 shown in FIGS. 4A to 4G are examples, and are not limited to these shapes. The shape of the storage recess 29 may be, for example, a substantially conical shape, and the apex portion of the substantially conical shape is rounded. The shape of the storage recess 29 may be a non-axisymmetric shape. For example, a part of the storage recess 29 in the circumferential direction is formed on a flat surface, and the remaining part in the circumferential direction is formed in a curved shape that bulges outward. May be.

Moreover, the thickness of the light guide 25 and the ratio of the thickness between the central portion and the end in the surface direction of the light guide 25 are arbitrary depending on the size of the light source 23, the light distribution on the light exit surface 25a of the light guide 25, and the like Can be changed. Further, by changing the thickness of the light guide 25, the shape of the housing recess 29, the shape of the inclined surface 25b, etc., the illuminance distribution or the luminance distribution in the surface direction on the exit surface 25a of the light guide 25 changes.
In the light guide 25 configured as described above, the luminance distribution in the surface direction of the light of the light source 23 on the emission surface 25a has the highest luminance at the central portion of the emission surface 25a, and the end portion of the emission surface 25a. The brightness decreases toward the. That is, a region of the emission surface 25a that overlaps the light source 23 and the light guide 25 in the thickness direction is an illuminance or luminance peak region where the luminance of the light from the light source 23 is highest.

  The optical sheet 27 is disposed so as to face the emission surface 25a of the light guide 25, and is configured to transmit the light emitted from the emission surface 25a of the light guide 25 and make it incident on the liquid crystal display element 13. ing. The optical sheet 27 is formed in a rectangular shape in plan view. The optical sheet 27 is formed on the base material and has a light transmitting property. The optical sheet 27 extends over the entire emission surface 41a so as to protrude from the emission surface 41a. A plurality of lens portions (optical elements) 43 provided integrally and a light reflecting layer 45 provided integrally over the incident surface 41 b of the translucent substrate 41 are provided. In addition, the exit surface 41a of the translucent substrate 41 indicates a surface on the display screen side from which light exits, and the entrance surface 41b faces the exit surface 25a of the light guide 25 and exits from the exit surface 25a. The surface where light enters is shown.

Each lens portion 43 is formed so as to collect light emitted from the emission surface 41a of the translucent substrate 41, and a flat surface facing the emission surface 41a of the translucent substrate 41 in a sectional view. And a convex curved surface formed so as to protrude from the emission surface. Note that the specific cross-sectional shape of the lens portion 43 may be bilaterally symmetric as illustrated, but may be bilaterally asymmetric. That is, for example, the lens portion 43 is formed in a linear shape on one side and is formed in a convex curve shape on the other side, and the linear shape and the curved shape are rounded and connected at the apex portion of the lens portion 43. But you can.
Among the plurality of lens portions 43, the cross section of the lens portion 43 disposed at a position overlapping the light source 23 and the translucent base material 41 in the thickness direction has the smallest width dimension orthogonal to the optical axis. Yes. And the width dimension of the cross section of the lens part 43 is formed so large that it leaves | separates from the light source 23 along the output surface 41a of the translucent base material 41. FIG. The cross-sectional shapes of the lens portions 43 having different width dimensions are similar to each other, and as a result, their height dimensions are different from each other. That is, the contact angles of the curved surfaces of the plurality of lens portions 43 on the emission surface 41a of the translucent substrate 41 are equal to each other.

As an arrangement pattern of the plurality of lens portions 43 having the cross-sectional shape as described above, for example, the following can be considered.
For example, as shown in FIG. 5, the light-transmitting substrate 41 may be arranged concentrically as viewed from the emission surface 41 a side. That is, when viewed from the emission surface 41a side of the translucent substrate 41, one lens portion 43 that overlaps the light source 23 is formed in a circular shape centering on the light source 23, and the other plurality of lens portions 43 are one lens. It is formed in an annular shape centering on the portion 43. In this case, the AA arrow cross-sectional view of FIG. 5 is the cross-section of FIG.
For example, as shown in FIG. 6, a plurality of lens portions 43 (cylindrical lenses) whose longitudinal direction is one direction along the emission surface 41 a of the translucent substrate 41 are arranged in one direction and a direction orthogonal thereto. As a whole, it is possible to construct a cross lenticular array. That is, in this configuration, a plurality of lens portions 43 formed in a rectangular shape in plan view are arranged in the vertical and horizontal directions of the emission surface 41 a of the translucent substrate 41. In this case, the BB arrow cross-sectional view and CC arrow cross-sectional view of FIG.

Further, for example, as shown in FIG. 7, when viewed from the emission surface 41 a side of the translucent substrate 41, one lens portion 43 is formed in a circular shape in plan view with the light source 23 as the center, and a plurality of other lenses It can be mentioned that the portions 43 are arranged radially in a direction away from the one lens portion 43 to constitute a so-called microlens array as a whole. In this case, the cross-sectional view taken along the line DD in FIG. 7 is the cross-section in FIG. In the illustrated example, each lens portion 43 is formed in a circular shape in plan view, but may be formed in, for example, a rectangular shape in plan view as long as the plurality of lens portions 43 are formed in a similar shape in plan view. .
For example, as shown in FIGS. 8 and 9, when viewed from the emission surface 41 a side of the translucent substrate 41, the plurality of lens portions 43 are formed on the emission surface 41 a of the translucent substrate 41 around the light source 23. It is mentioned that it forms radially along. In this configuration, as shown in FIG. 9A, the thickness in the longitudinal direction of each lens portion 43 is guided along the emission surface 41 a of the translucent substrate 41 starting from the portion directly above the light source 23. The thickness increases toward the end of the body 25. The cross-sectional shape in the width direction of each lens portion 43 is a shape having a convex curved surface as shown in FIG.

The lens unit 43 configured as described above is, for example, a well-known extrusion molding method, injection molding method, or heat treatment using PET, PC, PMMA, COP (cycloolefin polymer), acrylonitrile styrene copolymer, or the like. It is formed by the press molding method. In this case, the translucent base material 41 and the lens portion 43 may be made from different base materials of different materials as shown in FIG. 10A, for example, as shown in FIG. As shown, you may comprise from one base material which consists of the same material. Further, the incident surface 41b of the translucent substrate 41 may be molded with a step 41c as shown in FIG. 10C, for example. Further, the lens unit 43 may be molded on the translucent substrate 41 using, for example, UV or radiation curable resin (the type is not particularly limited as long as the resin includes a material curable by UV or radiation). Good.
In addition, when the some lens part 43 is arranged concentrically, it may be produced in planar view circular shape also including the translucent base material 41. FIG. In this case, the lens sheet composed of the translucent base material 41 and the lens portion 43 may be cut and cut into a polygonal shape (rectangular shape, quadrangular shape, regular hexagonal shape, etc.). As a cutting method, a method using a blade such as a cutter or a circular saw, laser cutting, punching, or the like may be used. Further, the cutting timing may be performed at any stage of the lens sheet, the optical sheet 27, and the backlight unit 21. However, from the viewpoint of reducing the loss of members, it is preferable to cut at the stage of the lens sheet.

  As shown in FIGS. 2 and 9, the light reflecting layer 45 is configured to reflect the light traveling from the light exit surface 25 a of the light guide 25 toward the translucent substrate 41. The light reflecting layer 45 is formed with a plurality of openings 46 penetrating in the thickness direction. Each opening 46 is disposed at a position overlapping the optical axis of the lens portion 43 and the thickness direction of the translucent substrate 41, and is formed narrower than the width dimension of the lens portion 43 directly above each. . The opening 46 arranged at the position where the light source 23 and the translucent substrate 41 overlap in the thickness direction is formed with the smallest opening area, and the other opening 46 is emitted from the translucent substrate 41. As the distance from the light source 23 increases along the surface 41a, the opening area increases. Moreover, the planar view shape of each opening part 46 is formed in the shape according to the shape of the lens part 43 shown to FIGS. For example, when the planar view shape of the lens portion 43 is an annular shape shown in FIG. 3, the planar view shape of the opening 46 is also an annular shape. Further, the opening 46 may be formed by a slit (cut) that is formed in the light reflection layer 45 and selectively transmits light, for example.

In the light reflecting layer 45, as shown in FIG. 10, the central axis O2 of the opening 46 is emitted from the translucent substrate 41 with respect to the optical axis O1 of the lens unit 43 overlapping the opening 46. There are those that deviate in the direction along the surface 41a (one opening 46A) and those that coincide with the optical axis O1 of the lens portion 43 that overlaps the opening 46 (other openings 46B).
Here, one opening 46A in which the central axis O2 is deviated from the optical axis O1 of the lens portion 43 is, as shown in FIG. 11A, light diffusion described later from the emission surface 25a of the light guide 25. Light that is emitted through the layer 51 and incident on the incident surface 41b of the translucent substrate 41 through the one opening 46A is obliquely incident on the incident surface 41b at a predetermined incident angle θ. It is formed at a position having a light distribution where the luminance of the light (oblique light) L1 is the highest.

  Specifically, for example, as shown in FIG. 11A, the opening 46A of one opening 46A is formed along the incident surface 41b of the translucent substrate 41 so as to be almost opposite to the direction of the oblique light L1. When the central axis O2 and the optical axis O1 of the lens unit 43 are arranged in order, as shown in FIG. 11B, compared to the case where the central axis O2 and the optical axis O1 coincide, The direction of the highest oblique light L1 can be made closer to the normal direction of the exit surface 41a of the translucent substrate 41 in the lens portion 43 corresponding to one opening 46A. That is, the incident angle of the light incident on the transmissive substrate 41 through the other opening 46B and emitted from the lens unit 43 is θ1, and the light incident through the one opening 46A is incident on the lens unit 43. When the emission angle of the emitted light is θ2, θ2 <θ1. Note that these emission angles θ1 and θ2 indicate the inclination angles of the emitted light with respect to the normal direction of the emission surface 41a of the transmissive substrate 41. Further, the magnitude of the difference between these two emission angles θ1 and θ2 can be arbitrarily changed by changing the distance between the central axis O2 and the optical axis O1.

From the above, in this optical sheet 27, the direction of the light emitted from the plurality of lens portions 43 even if the light distribution of the light emitted from the emission surface 25a of the light guide 25 is uneven or uneven. Can be aligned in the normal direction. In this case, the positions of the plurality of openings 46 may be set as follows.
The position of the opening 46A corresponding to the exit surface area of the light guide 25 from which the light distribution distribution light with the highest luminance of the oblique light L1 is emitted is the center axis O2 and the light as shown in FIG. What is necessary is just to set so that the axis | shaft O1 may shift | deviate. Further, light having a light distribution distribution in which the luminance of light incident substantially perpendicular to the incident surface 41b of the translucent substrate 41 is highest, or light having a light distribution distribution in which the luminance is substantially uniform in the angular direction is emitted. The position of the opening 46B corresponding to the region of the light exit surface 25a of the light guide 25 to be set may be set so that the central axis O2 and the optical axis O1 coincide with each other as shown in FIG.
Thereby, light with high luminance can be emitted from the optical sheet 27 in the normal direction. That is, the light emitted from the optical sheet 27 has the highest luminance of the light emitted in the normal direction, and the light having the luminance distribution in the angular direction in which the luminance of the light becomes smoother as the angle with respect to the normal direction increases. Become.
In the optical sheet 27, the light reflecting layer 45, the position of the opening 46, and the opening of the opening 46 are appropriately set according to the illuminance distribution or luminance distribution in the surface direction on the exit surface 25a of the light guide 25 described above. The area may be set.

  The light reflection layer 45 configured in this way is made of, for example, a white layer or a metal layer. Here, as a material of the white layer, for example, a composite material in which a white pigment made of an inorganic substance such as titanium dioxide, barium sulfate, and magnesium oxide is mixed in a transparent resin can be used. Moreover, as a metal layer, the vapor deposition layer which consists of material with high reflectivity and few light absorptions, such as silver and aluminum, can be used, for example.

The light reflecting layer 45 may be formed on the incident surface 41b of the translucent substrate 41 by transfer or vapor deposition, but gravure printing, screen printing, ink jet method, planographic printing, letterpress printing (for example, flexographic printing), etc. It is more preferable to form by this printing method. In the case of the printing method, a light reflection layer having an opening pattern can be directly formed on the incident surface 41 b of the translucent substrate 41.
In the case of the printing method, for example, as described above, the light reflecting layer 45 having the opening can be easily formed by providing the step 41c on the incident surface 41b when the translucent substrate 41 is manufactured. it can.

  Further, as shown in FIGS. 2 and 9, the backlight unit 21 emits light emitted from the emission surface 25 a of the light guide 25 toward the optical sheet 27 between the light guide 25 and the optical sheet 27. A diffusing light diffusion layer 51 is provided. The light diffusing layer 51 is configured by mixing fine particles (light diffusing particles) 53 for scattering light into a transparent resin material, and is fixed to the emission surface 25 a of the light guide 25. Further, the emission surface 51 a of the light diffusion layer 51 that emits light toward the optical sheet 27 is formed flat like the emission surface 25 a of the light guide 25. The light diffusion layer 51 may be integrally formed when the light guide 25 is manufactured, or may be fixed to the light exit surface 25a of the light guide 25 after being formed separately from the light guide 25. In the case where the light diffusion layer 51 and the light guide 25 are integrally formed, the light diffusion layer 51 is preferably made of the same transparent resin material as that of the light guide 25, but is made of a different transparent resin material. May be.

And the optical sheet 27 mentioned above is being fixed to the output surface 25a of the light guide 25 through the light-diffusion layer 51 by the joining layers 55, such as a translucent adhesive and adhesive agent. Here, it is preferable that the bonding layer 55 does not enter the opening 46 of the light reflecting layer 45. That is, it is preferable that an air layer 59 defined by the opening 46 is formed between the light diffusion layer 51 and the translucent substrate 41 as illustrated. By thus defining the air layer 59 having a refractive index lower than that of the translucent substrate 41, the light is efficiently collected when the light enters the translucent substrate 41 from the air layer 59. be able to.
For example, the optical sheet 27 and the light guide 25 may be fixed to a housing (not shown) of the display device 100 without using the bonding layer 55, for example. In this case, as shown in FIG. 12, for example, a gap may be formed between the optical sheet 27 and the light guide 25, or for example, this gap may not be provided.

  As shown in FIG. 1, the backlight device 11 is configured by connecting the above-described backlight unit 21 at the end of the light guide 25, and the light exit surfaces 25 a of the plurality of light guides 25 are the same. It is flat. In the illustrated example, the end surface of the light guide 25 is formed as a flat surface. However, for example, an uneven shape that engages with the end surfaces of the light guides 25 adjacent to each other may be formed. By forming in this way, it is possible to prevent a gap penetrating in the thickness direction of the light guide 25 between the end faces of the light guides 25 adjacent to each other.

As described above, in the optical sheet 27 and the backlight unit 21 according to the present embodiment, it corresponds to the illuminance or the luminance peak region where the luminance of the light from the light source 23 becomes the highest among the emission surfaces 25a of the light guide 25. The opening 46 formed in the position is formed to be the smallest, and the opening 46 is formed to be larger in a region where the luminance of light on the light exit surface 25a of the light guide 25 is reduced. For this reason, the amount of light blocked in the light reflecting layer 45 can be increased as the luminance of light on the light exit surface 25a of the light guide 25 is increased. Therefore, even if the luminance distribution in the surface direction of the light on the exit surface 25a of the light guide 25 is non-uniform, the light emitted from the exit surface 25a of the light guide 25 passes through each opening 46 of the light reflecting layer 45. By doing so, it is possible to efficiently suppress luminance unevenness of light emitted from the emission surface 41a of the translucent substrate 41.
The optical sheet 27 is provided with a light reflecting layer 45 for suppressing luminance unevenness and a lens portion 43 for condensing light that has passed through the opening 46 integrally on both surfaces of the translucent substrate 41. Therefore, by providing the optical sheet 27 in the backlight unit 21, the backlight device 11, and the display device 100, it is possible to easily reduce the thickness thereof.

Further, the optical sheet 27 is adjusted by shifting the central axis O2 of the opening 46 and the optical axis O1 of the lens portion 43 overlapping the opening 46 in a direction along the emission surface 41a of the translucent substrate 41. It is possible to control the direction of light emitted from the emission surface. Specifically, as the light emitted from the optical sheet 27, the luminance of the light emitted in the normal direction of the display screen is the highest, and the luminance distribution in the angular direction in which the luminance becomes smoother as the angle with respect to the normal direction increases. Can be obtained.
Furthermore, since the light reflecting layer 45 having a plurality of openings 46 can be easily formed on the incident surface 41b of the translucent substrate 41 by a printing method, the number of manufacturing steps of the optical sheet 27 can be reduced and the manufacturing efficiency can be improved. Can be planned.
Moreover, since all the opening parts 46 can be positioned with respect to each lens part 43 only by determining the printing position of the light reflection layer 45 with respect to the translucent base material 41, it is mutually in the thickness direction of the translucent base material 41 There is no need to align the relative positions of the overlapping opening 46 and lens unit 43 individually. Therefore, the optical sheet 27 can be easily manufactured and its manufacturing cost can be reduced.

Moreover, since the width dimension of the lens part 43 is formed so that the brightness | luminance of the light in the output surface 25a of the light guide 25 becomes small, the condensing efficiency by the lens part 43 becomes high, so that illumination intensity or a brightness | luminance becomes small, The luminance unevenness of the light emitted from the plurality of lens portions 43 can be further reduced.
Further, by providing the light diffusion layer 51, the light from the light source 23 is diffused before being incident on the optical sheet 27, so that the luminance unevenness of the light incident on the optical sheet 27 from the light guide 25 side is reduced. be able to.

Further, the light reflecting plate 31 is provided on the inclined surface 25b of the light guide 25, or the reflector 33 that closes the opening of the housing recess 29 is provided, so that most of the light from the light source 23 is emitted from the light exit surface 25a of the light guide 25. Since it can be made to radiate | emit, the utilization efficiency of the light of the light source 23 can be improved.
And according to the backlight apparatus 11 and the display apparatus 100 which concern on this embodiment, the enlargement of the screen in the display apparatus 100 can be easily achieved besides the effect mentioned above. In addition, by integrally forming the plurality of optical sheets 27 and the light guide 25, optical influences such as refraction may occur when light passes across the connecting portions of the backlight units 21 adjacent to each other. Can be prevented. Therefore, it is possible to prevent the occurrence of luminance unevenness based on the above-described connection portion.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the display device 100, an optical sheet that achieves a diffusion / condensing effect by light refraction / transmission / reflection / polarization may be disposed between the liquid crystal display element 13 and the optical sheet 27. Examples of the optical sheet include a diffusion film, a prism sheet, and a polarization separation / reflection sheet. Even when configured in this manner, the same effects as those of the above-described embodiment can be obtained.
Further, in the backlight device 11, for example, as shown in FIG. 14, a plurality of optical sheets 27 may be integrally formed, or for example, as shown in FIG. 15, a plurality of light guides 25 are integrally formed. Further, the plurality of light diffusion layers 51 may be integrally formed. In addition, integral formation of these light guide 25, the optical sheet 27, and the light-diffusion layer 51 is not restricted to the example of illustration, You may implement it combining suitably.

Furthermore, in the state of the backlight device 11 in which the plurality of backlight units 21 are connected, the emission surfaces 25a of the plurality of light guides 25 are in the same plane. However, the present invention is not limited to this. The whole or part of the emission surface 25a of the body 25 may be the same curved surface. In this case, the exit surfaces 25a of the plurality of light guides 25 may be formed into curved surfaces having the same curvature.
In addition, in a state where a plurality of backlight units 21 are connected, each light guide 25 may be configured such that undulations with a constant period are formed on the entire surface by the emission surfaces 25 a of the plurality of light guides 25.
Further, the display device 100 includes the backlight device 11 including the plurality of backlight units 21. However, for example, the display device 100 may include one backlight unit 21.

In the above embodiment, it has been described that the luminance of light emitted in the normal direction of the display screen is maximized. However, in the optical sheet 27 of the present invention, the luminance of light emitted in a specific direction other than the normal direction is set. It can also be the largest. In this case, what is necessary is just to set the position of the opening part 46 corresponding to each lens part 43 as follows.
That is, in the state where the optical axis O1 of one lens unit 43 and the central axis O2 of the opening 46 corresponding to this coincide with each other, the direction of the light having the highest luminance emitted from the one lens unit 43 is the target. When substantially matching the specific direction, the position of the opening 46 corresponding to the lens portion 43 may be set as shown in FIG.
In addition, in a state where the optical axis O1 of one lens unit 43 and the central axis O2 of the opening 46 corresponding to the lens unit 43 coincide with each other, the direction of the light having the highest luminance emitted from the one lens unit 43 is the target. When the inclination angle is larger than the specific direction, the position of the opening 46 corresponding to the lens unit 43 may be set as shown in FIG.

Then, in a state where the optical axis O1 of the one lens unit 43 and the central axis O2 of the opening 46 corresponding thereto match, the direction of the light having the highest luminance emitted from the one lens unit 43 is the target specification. When the inclination angle is smaller than the direction, for example, as shown in FIG. 16, the one along the incident surface 41 a of the translucent substrate 41 so as to substantially coincide with the direction of the incident oblique light L 1. The central axis O2 of the opening 46 and the optical axis O1 of the lens unit 43 may be arranged in order.
In this case, as shown in FIG. 11B, compared with the case where the central axis O2 and the optical axis O1 coincide with each other, the direction of the oblique light L1 having the highest luminance is set to one opening 46A. The corresponding lens portion 43 can be further separated from the normal direction of the emission surface 41a of the translucent substrate 41. In other words, θ2 <θ1 <θ3, where θ3 is an emission angle of light incident through one opening 46A and emitted from the lens unit 43. Note that the emission angle θ3 indicates the inclination angle of the emitted light with respect to the normal direction of the emission surface 41a of the transmissive substrate 41, similarly to the emission angles θ1 and θ2 described above. Further, the magnitude of the difference between the two emission angles θ1 and θ3 can be arbitrarily changed by changing the distance between the central axis O2 and the optical axis O1.

As described above, by setting the position of the opening 46, the luminance of the light emitted from the optical sheet 27 in an arbitrary specific direction is the largest, and the angular direction in which the luminance becomes smoother as the angle with respect to the specific direction increases. Can be obtained. That is, light having a luminance distribution in a desired angular direction can be emitted from the optical sheet 27 toward the liquid crystal display element 13.
Note that one opening 46A formed in the light reflecting layer 45 may be formed so as to overlap the optical axis O1 of the lens unit 43 and its vicinity as shown in FIG. 11A and FIG. It may be formed so as not to overlap with the optical axis O1 of the lens portion 43 or the vicinity thereof. That is, the one opening 46A may be formed so as to be shifted from the optical axis O1, for example.

Moreover, in the said embodiment, although the backlight unit 21 which used the light source 23 as the point light source was demonstrated, this invention can also be applied to the backlight unit which used the light source as the linear rod-shaped light source. Hereinafter, the configuration of the backlight unit when a rod-shaped light source is used will be described with reference to FIG.
As shown in FIG. 17, the backlight unit 121 includes a light source 123 that is a rod-shaped light source, a light guide 125 and an optical sheet that are sequentially arranged on the display screen side of the light source 123, as in the above embodiment. 127.
The cross-sectional shape of the light guide 125 is similar to the light guide 25 of the above-described embodiment, in which an accommodation recess 129 for accommodating the light source 123 is formed on the other surface, and inclined surfaces formed on both sides of the accommodation recess 129. 125b and a flat output surface 125a are formed. Here, the housing recess 129 is formed to extend in one direction along the emission surface 125 a of the light guide 125. The accommodating recess 129 is formed in the thickest portion of the light guide 125 having the largest thickness. Furthermore, the inclined surface 125b is formed so as to become thinner toward the direction orthogonal to one direction along the emission surface 125a of the light guide 125. As a result, the light guide 125 has the thinnest thickness at the end in the orthogonal direction.

Examples of the light source 123 housed in the housing recess 129 include a normal fluorescent tube, a cold cathode tube, a hot cathode tube, an external electrode tube, LEDs and semiconductor lasers arranged in a row, etc. A cold cathode tube, an external electrode tube, or an LED arranged in a row is preferable.
In addition, the light source 123 includes, for example, a transparent columnar light guide formed in a columnar shape or a prism shape extending in the one direction, and LEDs disposed above and below the columnar light guide along the thickness direction. It may be. When the light source 123 is configured as described above, when the LED light is incident from above and below the columnar light guide, the LED light can be emitted to the side of the columnar light guide.

Further, the optical sheet 127 includes a light reflecting layer 145 having a translucent substrate 141, a plurality of lens portions (optical elements) 143, and an opening 146, as in the above embodiment. Each lens part 143 arranged on the emission surface 141a of the translucent substrate 141 is a unit lens formed in a long shape extending in the one direction. The plurality of lens portions 143 are arranged in a direction parallel to the one direction along the emission surface 141 a of the translucent substrate 141. Moreover, the cross section of the lens part 143 arranged in the position which overlaps the light source 123 and the thickness direction of the translucent base material 141 among the plurality of lens parts 143 is formed with the smallest width dimension along the arrangement direction. Yes. The width dimension of the lens portion 143 is formed so as to be farther from the light source 123 along the arrangement direction. In the illustrated example, as in the above embodiment, the cross-sectional shapes of the plurality of lens portions 143 are similar to each other.
Further, the plurality of openings 146 of the light reflecting layer 145 are formed in a slit shape extending in the longitudinal direction in correspondence with each lens portion 143 formed in a long shape, and the array of the plurality of lens portions 143 is arranged. Arranged at intervals in the direction.
The backlight unit 121 configured in this way also has the same effect as the above embodiment.

  Further, the housing recesses 29 and 129 for housing the light sources 23 and 123 in the light guides 25 and 125 are not limited to being formed on the other surface side of the light guides 25 and 125, but the thick wall of the light guide 25. As long as it is formed in the portion, for example, it may be formed on the emission surfaces 25a and 125a of the light guides 25 and 125. In this configuration, the openings of the housing recesses 29 and 129 are closed by the same reflector 33 as in the above-described embodiment, so that the light from the light sources 23 and 123 does not pass through the light guides 25 and 125, and the optical sheets 27 and 127. It is preferable to prevent direct incidence on the light. And when comprised in this way, after the light of the light sources 23 and 123 reflects in the inclined surfaces 25b and 125b of the light guides 25 and 125, or the light reflection board 31, it is radiate | emitted from the output surfaces 25a and 125a. Become.

In addition, the backlight units 21 and 121 are configured to include the light diffusion layer 51 fixed to the emission surfaces 25a and 125a of the light guides 25 and 125, but at least the light sources 23 and 123 and the optical sheet 27, It is only necessary that a light diffusion region for diffusing light is formed between the first and second light sources. Therefore, for example, the light guides 25 and 125 themselves may include a light diffusion region in which the fine particles 53 are mixed between the emission surfaces 25 a and 125 a and the light sources 23 and 123. For example, as shown in FIG. 18, the light diffusion region may be formed over the entire light guide 25, but as shown in FIG. 19, for example, it is more preferable that the light diffusion region is formed close to the emission surface 25 a side. In these cases, the number of components of the backlight units 21 and 121 can be reduced, and the backlight units 21 and 121 can be made thinner.
However, when the luminance unevenness on the screen is sufficiently eliminated by the optical sheets 27 and 127, the light diffusion layer 51 and the light diffusion region described above may not be formed.

  Furthermore, although the cross-sectional shapes of the lens portions 43 and 143 having different width dimensions are similar to each other, for example, the height dimensions may be substantially equal. In the case of this configuration, since the thickness of the optical sheets 27 and 127 can be reduced, the backlight units 21 and 121, the backlight device 11, and the display device 100 can be further reduced in thickness. In addition, when the cross-sectional shapes of the lens portions 43 and 143 having different width dimensions are not similar, it is not always necessary to make the height dimensions equal, and the lens portions on the emission surfaces 41a and 141a of the translucent base materials 41 and 141 are not necessarily required. 43 and 143 should just have different inclination angles. Specifically, among the plurality of lens portions 43 and 143, the inclination angle of the lens portions 43 and 143 arranged at the position where the light sources 23 and 123 and the light-transmitting base materials 41 and 141 overlap in the thickness direction is the largest. Further, it is only necessary that the inclination angles of the lens portions 43 and 143 are made smaller as the distance from the light sources 23 and 123 increases along the emission surfaces 41a and 141a of the translucent base materials 41 and 141. Even if the inclination angles are varied in this way, the condensing region by the lens portions 43 and 143 can be changed as in the case of the similar shape.

Further, the sizes of the lens portions 43 and 143 and the openings 46 and 146 are determined based on the positions of the light sources 23 and 123, but from the light sources 23 and 123 on the emission surfaces 25 a and 125 a of the light guides 25 and 125. What is necessary is just to determine based on the illumination intensity or brightness | luminance peak area | region where the brightness | luminance of this light becomes the highest. For example, when the illuminance or luminance peak region is an annular region around the position where it overlaps with the light source 23 in the thickness direction on the emission surfaces 25a and 125a, the thickness direction of the annular region and the translucent substrate 41 The width dimensions of the lens portions 43 and 143 disposed on the emission surfaces 41a and 141a of the translucent base materials 41 and 141 that overlap with each other, and the opening areas of the openings 46 and 146 formed in the light reflecting layers 45 and 145 And the width of the lens portions 43 and 143 and the opening area of the openings 46 and 146 may be increased as the illuminance or luminance decreases.
If there are a plurality of illuminance or luminance peak areas, a plurality of openings 46 and 146 having the smallest opening area may be formed in correspondence with each illuminance or luminance peak area.

  Furthermore, although the plurality of lens portions 43 and 143 are formed on the emission surfaces 41a and 141a of the translucent substrates 41 and 141, they are emitted from at least the emission surfaces 41a and 141a of the translucent substrates 41 and 141. It suffices if a plurality of optical elements that collect the collected light are formed. That is, for example, as shown in FIG. 20, a plurality of prisms (optical elements) 44 may be formed on the emission surface 41 a of the translucent substrate 41. Even in this case, the width dimension of the cross section of the plurality of prisms 44 is based on the illuminance or luminance peak region where the luminance of the light from the light source 23 is highest on the exit surface 25a of the light guide 25 as in the case of the lens portion 43. Can be determined.

Further, for example, the plurality of prisms 44 may be formed in a similar shape, or the height dimensions of the plurality of prisms 44 may be aligned as in the illustrated example. In addition, when aligning the height dimension of the plurality of prisms 44, the apex angle of one prism 44 arranged immediately above the illuminance or luminance peak area of the light on the exit surface 25a of the light guide 25 is minimized, As the distance from the illuminance or luminance peak region along the emission surface 41a of the translucent substrate 41 increases, the apex angle of the other prisms 44 may be increased.
Furthermore, the planar view shape of the plurality of prisms 44 may be formed, for example, in the shape shown in FIGS. 5 to 8 or FIG.
Even when the prism 44 is provided as described above, the positional relationship between the central axis of the opening and the optical axis O3 of the prism 44 is adjusted so that a luminance distribution in a desired angular direction can be obtained, as in the above embodiment. It is preferable that the central axes of some of the openings and the optical axis O3 of the prism 44 are shifted from each other.

  Moreover, in the said embodiment, although the light reflection layers 45 and 145 were provided in the entrance surfaces 41b and 141b of the translucent base materials 41 and 141, if at least the light shielding layer which interrupts | blocks light is provided Good. Therefore, it is only necessary to form openings 46 and 146 similar to those in the above embodiment in the light shielding layer.

It is a schematic sectional drawing which shows the display apparatus which concerns on 1st Embodiment of this invention. It is a schematic sectional drawing which shows an example of the backlight unit with which the display apparatus of FIG. 1 is equipped. It is a schematic sectional drawing which shows the modification of the light guide with which the backlight unit of FIG. 2 is equipped. It is a schematic sectional drawing which shows the modification of the accommodation recessed part in the light guide with which the backlight unit of FIG. 2 is equipped. FIG. 3 is a schematic top view illustrating an arrangement example of lens portions in the backlight unit of FIG. 2. FIG. 3 is a schematic top view illustrating an arrangement example of lens portions in the backlight unit of FIG. 2. FIG. 3 is a schematic top view illustrating an arrangement example of lens portions in the backlight unit of FIG. 2. It is a schematic top view which shows the example of arrangement | positioning of a lens part in an example of the backlight unit with which the display apparatus of FIG. 1 is equipped. 2 shows an example of a backlight unit provided in the display device of FIG. 1, (a) is a cross-sectional view taken along the line EE in FIG. 8, and (b) is a cross-sectional view taken along the line FF in FIG. 8. It is a schematic sectional drawing which shows the optical sheet with which the backlight unit of FIG. 2 is equipped. In the backlight unit shown in FIG. 2, it is an expanded sectional view which shows the outline of the positional relationship of a lens part and the opening part of a light reflection layer, (a) has shifted | deviated from the optical axis of a lens part, and the central axis of an opening part. (B) shows a case where the optical axis of the lens portion and the central axis of the opening portion coincide with each other. It is a schematic sectional drawing which shows the modification of the backlight unit shown in FIG. It is a schematic sectional drawing which shows an example of the light source used in the backlight unit shown in FIG. It is a schematic sectional drawing which shows the display apparatus which concerns on other embodiment of this invention. It is a schematic sectional drawing which shows the display apparatus which concerns on other embodiment of this invention. In the optical sheet which concerns on other embodiment of this invention, it is an expanded sectional view which shows the outline of the positional relationship of a lens part and the opening part of a light reflection layer. The backlight unit which concerns on other embodiment of this invention is shown, (a) is schematic sectional drawing, (b) is a schematic top view of the lens part with which this is provided. It is a schematic sectional drawing which shows the light guide which concerns on other embodiment of this invention. It is a schematic sectional drawing which shows the light guide which concerns on other embodiment of this invention. It is a schematic sectional drawing which shows the optical sheet which concerns on other embodiment of this invention.

Explanation of symbols

11 Backlight device 13 Liquid crystal display element (image display unit)
21, 121 Backlight unit 23, 123 Light source 25, 125 Light guide 25a, 125a Emission surface 25b, 125b Inclined surface 27, 127 Optical sheet 29, 129 Housing recess 41, 141 Translucent base material 41a, 141a Emission surface 41b , 141b Incident surface 43, 143 Lens part (optical element)
44 Prism (optical element)
45,145 Light reflecting layer (light shielding layer)
46 (46A, 46B), 146 opening 51 light diffusion layer 53 fine particles (light diffusion particles)
L1 Oblique light O1 Optical axis O2 Center axis

Claims (25)

It is formed in a substantially plate shape, and one surface forms an emission surface for emitting light from the light source, and is disposed opposite to the emission surface with respect to a light guide configured to emit the light from the entire emission surface. An optical sheet for controlling light emitted from the emission surface,
A light-transmissive translucent substrate formed on a base material, wherein one surface forms an incident surface on which light from the light exit surface of the light guide is incident and the other surface forms a light output surface; A plurality of optical elements that are integrally provided on the exit surface of the translucent substrate so as to protrude from the exit surface of the translucent substrate and collect light emitted from the exit surface of the translucent substrate; A light shielding layer that is integrally provided on the incident surface of the translucent substrate and blocks light emitted from the emission surface of the light guide,
In the light shielding layer, a plurality of openings are formed that penetrate in the thickness direction of the light shielding layer so as to overlap the optical axis of each optical element and the thickness direction of the light transmissive substrate,
The opening disposed at a position facing the illuminance or luminance peak area where the illuminance or luminance of the light from the light source is highest on the exit surface of the light guide is formed with the smallest opening area,
As the illuminance or brightness decreases along the incident surface of the translucent substrate, the opening area of the opening increases.
Furthermore, the optical sheet is characterized in that the central axis of at least one opening is shifted in a direction along the optical axis of the optical element overlapping therewith and the emission surface of the translucent substrate. Light that exits from the exit surface of the light guide and enters the entrance surface of the translucent substrate through one opening is obliquely incident on the entrance surface of the translucent substrate. It has a light distribution that maximizes the luminance of the oblique light,
Arranging the central axis of the one opening and the optical axis of the optical element in order along the incident surface of the translucent substrate so as to be almost opposite to the direction of the oblique light. The optical sheet according to claim 1, wherein Light that exits from the exit surface of the light guide and enters the entrance surface of the translucent substrate through one opening is obliquely incident on the entrance surface of the translucent substrate. It has a light distribution that maximizes the luminance of the oblique light,
The center axis of the one opening and the optical axis of the optical element are arranged in order along the incident surface of the translucent substrate so as to substantially match the direction of the oblique light. The optical sheet according to claim 1.   The optical sheet according to any one of claims 1 to 3, wherein the light shielding layer is formed on an incident surface of the translucent substrate by gravure printing or screen printing. The optical element disposed at a position where the illuminance or luminance peak region on the light exit surface of the light guide overlaps with the thickness direction of the translucent substrate is formed with the smallest width dimension orthogonal to the optical axis. ,
5. The optical according to claim 1, wherein the width dimension of the optical element is increased as the illuminance or luminance decreases along the emission surface of the translucent substrate. Sheet.   6. The optical sheet according to claim 5, wherein cross-sectional shapes in the width direction of the plurality of optical elements orthogonal to the emission surface of the translucent substrate are similar to each other.   The cross-sectional shape in the width direction of the plurality of optical elements orthogonal to the exit surface of the translucent substrate is the illuminance or luminance peak region on the exit surface of the light guide and the thickness direction of the translucent substrate. The tilt angle of the optical element is decreased as the tilt angle of the optical element disposed at a position overlapping with the largest is formed and the illuminance or luminance decreases along the emission surface of the translucent substrate. The optical sheet according to claim 5, wherein the optical sheet is formed as follows.   8. The optical sheet according to claim 7, wherein height dimensions of the plurality of optical elements protruding from an emission surface of the translucent substrate are substantially equal to each other. The light source is a point light source, and the illuminance or luminance peak area is an area of the exit surface of the light guide that overlaps the point light source in the thickness direction of the light guide,
One optical element overlapping with the point light source is formed in a shape centered on the point light source when viewed from the exit surface side of the translucent substrate,
The optical sheet according to any one of claims 1 to 8, wherein a plurality of other optical elements are formed in a ring shape centered on the point light source. The light source is a point light source, and the illuminance or luminance peak area is an area of the exit surface of the light guide that overlaps the point light source in the thickness direction of the light guide,
A plurality of optical elements whose longitudinal direction is one direction along the emission surface of the translucent substrate are arranged in the one direction and a direction orthogonal to the one direction along the emission surface of the translucent substrate. The optical sheet according to any one of claims 1 to 8, wherein the optical sheet is characterized in that The light source is a point light source, and the illuminance or luminance peak area is an area of the exit surface of the light guide that overlaps the point light source in the thickness direction of the light guide,
One optical element overlapping with the point light source is formed in a shape centered on the point light source when viewed from the exit surface side of the translucent substrate,
The optical sheet according to any one of claims 1 to 8, wherein a plurality of other optical elements are arranged in a direction away from the one optical element. The light source is a point light source, and the illuminance or luminance peak area is an area of the exit surface of the light guide that overlaps the point light source in the thickness direction of the light guide,
The plurality of optical elements are formed radially along the exit surface of the translucent substrate with the point light source as the center, as viewed from the exit surface side of the translucent substrate. The optical sheet according to any one of claims 1 to 8. The light source is a rod-shaped light source extending in one direction along the light-emitting surface of the light guide, and the light-emitting surface of the light guide overlaps the illuminance or luminance peak region in the thickness direction of the light-guide and the light source. Is an area of
The plurality of optical elements are formed in a long shape extending in the one direction, and are arranged in a direction parallel to the one direction along an emission surface of the light guide. The optical sheet according to any one of claims 1 to 8.   The optical sheet according to any one of claims 1 to 13, wherein the optical element comprises a lens having a convex curved surface.   The optical sheet according to claim 1, wherein the optical element is a prism. A backlight unit comprising the optical sheet according to any one of claims 1 to 15, the light source, and the light guide.
The light guide is formed with an accommodation recess for accommodating the light source by being recessed from the emission surface or the other surface on the opposite side,
The light exit surface of the light guide is formed in a substantially flat surface,
The other surface is inclined so as to incline from the opening edge of the housing recess so that the thickness of the light guide decreases from the region where the housing recess is formed toward the end in the surface direction of the light guide. A backlight unit having a surface.   The backlight unit according to claim 16, wherein a light diffusion layer mixed with light diffusion particles is provided between the light guide and the optical sheet.   The backlight unit according to claim 16, wherein the light guide includes a light diffusion region in which light diffusion particles are mixed between an emission surface and the light source.   The backlight unit according to claim 16, wherein the light guide is manufactured by an injection molding method.   The backlight unit according to claim 16, wherein the light guide is manufactured by an extrusion molding method. The optical sheet and the light guide are fixed to each other,
The back according to any one of claims 16 to 20, wherein an air layer defined by the opening is formed between the light guide and the translucent substrate. Light unit.   The backlight unit according to any one of claims 16 to 21, wherein a plurality of the backlight units are connected and arranged along the emission surface of the light guide.   The backlight device according to claim 22, wherein the plurality of optical sheets are integrally formed.   The backlight device according to claim 22 or 23, wherein the plurality of light guides are integrally formed.   The backlight unit according to any one of Claims 16 to 21, or the backlight device according to any one of Claims 22 to 24, and an emission surface of the translucent substrate. And an image display unit that displays an image using light from the backlight unit or the backlight device as display light.

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