CN111522174A - Illumination device, display device, and method for manufacturing illumination device - Google Patents
Illumination device, display device, and method for manufacturing illumination device Download PDFInfo
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- CN111522174A CN111522174A CN201911236534.3A CN201911236534A CN111522174A CN 111522174 A CN111522174 A CN 111522174A CN 201911236534 A CN201911236534 A CN 201911236534A CN 111522174 A CN111522174 A CN 111522174A
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/1336—Illuminating devices
- G02F1/133615—Edge-illuminating devices, i.e. illuminating from the side
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- 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
- G02B6/0045—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 by shaping at least a portion of the light guide
- G02B6/0046—Tapered light guide, e.g. wedge-shaped light guide
- G02B6/0048—Tapered light guide, e.g. wedge-shaped light guide with stepwise taper
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- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Nonlinear Science (AREA)
- Mathematical Physics (AREA)
- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Planar Illumination Modules (AREA)
- Liquid Crystal (AREA)
Abstract
An illumination device of an embodiment includes: a1 st light source emitting laser light; and a light guide plate having a1 st side surface to which light from the 1 st light source is applied, a2 nd side surface opposite to the 1 st side surface, a1 st surface to reflect light incident from the 1 st side surface, and a2 nd surface to which light reflected by the 1 st surface is emitted. The 1 st side surface has a1 st region including a light incident region to which light from the 1 st light source is irradiated and a2 nd region to which light from the 1 st light source is not irradiated. The surface roughness of the 1 st region is less than the surface roughness of the 2 nd region.
Description
The present application claims priority based on japanese patent application 2019-.
Technical Field
Embodiments of the present invention relate to an illumination device, a display device, and a method for manufacturing an illumination device.
Background
For example, a display device such as a liquid crystal display device includes a display panel having pixels and an illumination device such as a backlight for illuminating the display panel. The illumination device includes a light source that emits light and a light guide plate that irradiates the light from the light source. Light from the light source enters the light guide plate from a side surface of the light guide plate, propagates through the light guide plate, and is emitted from an emission surface corresponding to one main surface of the light guide plate.
Further, for example, as disclosed in japanese patent application laid-open No. 2018-45990, an illumination device in which a point light source that emits a laser beam is disposed in the vicinity of a side surface of a light guide plate is proposed. The laser light incident on the light guide plate is reflected by a reflection structure such as a prism disposed on one main surface of the light guide plate, and is emitted from the other main surface.
If the light guide plate has minute irregularities on the side surface in the region irradiated with light from the light source, the light may have uneven brightness distribution on the light exit surface of the light guide plate due to the influence of the minute irregularities. When the light emitted from the light source is laser light, such unevenness in luminance distribution appears remarkably.
An object of the present disclosure is to provide an illumination device, a display device, and a method for manufacturing the illumination device, which can improve luminance distribution in a light exit surface of a light guide plate.
Disclosure of Invention
An illumination device of an embodiment includes: a1 st light source emitting laser light; and a light guide plate having a1 st side surface to which light from the 1 st light source is applied, a2 nd side surface opposite to the 1 st side surface, a1 st surface to reflect light incident from the 1 st side surface, and a2 nd surface to which light reflected by the 1 st surface is emitted. The 1 st side surface has a1 st region including a light incident region to which light from the 1 st light source is irradiated and a2 nd region to which light from the 1 st light source is not irradiated. The surface roughness of the 1 st region is less than the surface roughness of the 2 nd region.
The display device of an embodiment includes: the lighting device; and a display panel which is opposed to the 2 nd surface and displays an image using light emitted from the 2 nd surface.
The method for manufacturing the lighting device according to the embodiment includes the following steps: locally smoothing a surface of a mold of the light guide plate corresponding to the 1 st side surface; forming a1 st region corresponding to a portion of the surface that is smoothed and a2 nd region corresponding to a portion that is not smoothed, on the 1 st side surface by shaping the light guide plate using the mold; and the 1 st light source is disposed such that a light incident region of light from the 1 st light source is included in the 1 st region.
According to the above structure, the luminance distribution in the light exit surface of the light guide plate can be improved.
Drawings
Fig. 1 is a perspective view showing a schematic configuration of a display device according to the present embodiment.
Fig. 2 is a schematic sectional view of the display device.
Fig. 3 is a schematic plan view of an illumination device provided in the display device.
Fig. 4 is a schematic cross-sectional view of a light guide plate provided in the lighting device.
Fig. 5 is a schematic plan view for explaining the luminance unevenness in the light guide plate.
Fig. 6 is a view schematically showing an example of a method of processing a surface corresponding to a side surface of the mold for the light guide plate.
Fig. 7 is a schematic sectional view of a mold having the above-described surface.
Fig. 8 is a view schematically showing a method of processing a light guide plate according to the present embodiment.
Fig. 9 is a schematic side view of a light guide plate molded by a mold processed by the method shown in fig. 8.
Fig. 10 is a schematic plan view showing an example of the structure in the vicinity of the side surface of the illumination device.
Fig. 11 is a schematic plan view showing another example of the structure in the vicinity of the side surface of the illumination device.
Fig. 12 is a schematic plan view of the 1 st region in the side surface of the light guide plate.
Fig. 13 is a schematic plan view showing an example of a configuration applicable to the light source provided in the lighting device.
Fig. 14 is a schematic side view of the light source.
Fig. 15 is a schematic cross-sectional view showing another example of the arrangement of the light sources.
Detailed Description
An embodiment is described with reference to the accompanying drawings.
The disclosure is merely an example, and appropriate modifications that can be easily made by those skilled in the art to maintain the gist of the invention are naturally included in the scope of the invention. In order to make the description more clear, the drawings are schematic as compared with the actual embodiment, but the drawings are merely examples and do not limit the explanation of the present invention. In each drawing, the same or similar elements arranged in series may be omitted with reference numerals. In the present specification and the drawings, the same reference numerals are given to components that perform the same or similar functions to those of the components already described in the previous drawings, and redundant detailed description may be omitted.
In this embodiment, a transmissive liquid crystal display device is disclosed as an example of a display device. In addition, a backlight of a liquid crystal display device is disclosed as an example of the illumination device. However, the present embodiment is not intended to limit the application of the various technical ideas disclosed in the present embodiment to other types of display devices and lighting devices. As other types of display devices, for example, a liquid crystal display device having a reflection type function of reflecting external light in addition to a transmission type function and using the reflected light for display, a display device having a Mechanical display panel in which a Micro Electro Mechanical System (MEMS) shutter functions as an optical element, and the like are conceivable. As another type of illumination device, for example, a front light disposed in front of a display device is conceivable. In addition, the illumination device may be used for a different purpose from the illumination of the display device.
Fig. 1 is a perspective view showing a schematic configuration of a display device 1 according to the present embodiment. The display device 1 can be used for various devices such as a smartphone, a tablet terminal, a mobile phone terminal, a personal computer, a television receiving device, an in-vehicle device, a game machine, and a wearable terminal.
The display device 1 includes a display panel 2, an illumination device 3 serving as a backlight, a driver IC chip 4 (controller) for driving the display panel 2, and flexible circuit boards FPC1 and FPC2 for transmitting control signals to the display panel 2 and the illumination device 3. For example, the flexible circuit boards FPC1 and FPC2 are connected to a control module that controls the operation of the display panel 2 and the lighting device 3.
The display panel 2 includes a1 st substrate SUB1 (array substrate) and a2 nd substrate SUB2 (opposite substrate) opposite to the 1 st substrate SUB 1. The display panel 2 has a display area DA for displaying an image. The display panel 2 includes a plurality of pixels PX arranged in a matrix in the display area DA, for example.
The lighting device 3 includes a1 st light source LS1, a2 nd light source LS2, and a light guide plate LG opposing the 1 st substrate SUB 1. The 1 st light source LS1 is opposite to one side surface of the light guide plate LG, and the 2 nd light source LS2 is opposite to the other side surface of the light guide plate LG. In fig. 1, although one light source LS1 and one light source LS2 are shown, a plurality of 1 st light sources LS1 and a plurality of 2 nd light sources LS2 (see fig. 3) are actually provided.
As shown in FIG. 1, a1 st direction X, a2 nd direction Y and a3 rd direction Z are defined. The directions X, Y, Z are, for example, orthogonal to each other. In the present disclosure, a mode in which the display device 1 is viewed from a direction parallel to the 3 rd direction Z is referred to as a plan view. In the example of fig. 1, each of the substrates SUB1, SUB2 and the light guide plate LG has a short side along the 1 st direction X and a long side along the 2 nd direction Y, and has a rectangular shape in plan view. However, the shapes of the substrates SUB1 and SUB2 and the light guide plate LG are not limited to these, and the shape in plan view may be other shapes such as a square or a circle.
Fig. 2 is a schematic cross-sectional view of the display device 1 parallel to the Y-Z plane. The display panel 2 further includes a sealing member SL, a liquid crystal layer LC, a1 st polarizing plate PL1, and a2 nd polarizing plate PL 2. The substrates SUB1 and SUB2 are bonded to each other by a seal SL. The liquid crystal layer LC is sealed between the seal SL and the substrates SUB1 and SUB 2.
A1 st polarizing plate PL1 is attached to the lower surface (the surface facing the light guide plate LG) of the 1 st substrate SUB 1. A2 nd polarizing plate PL2 is attached to the upper surface (the surface not opposed to the 1 st substrate SUB 1) of the 2 nd substrate SUB 2. The polarizing axes of the polarizing plates PL1 and PL2 are, for example, orthogonal to each other.
The light guide plate LG includes a1 st surface 51, a2 nd surface 52 on the opposite side of the 1 st surface 51, a1 st side surface 53, and a2 nd side surface 54 on the opposite side of the 1 st side surface 53. The display panel 2 is opposed to the 2 nd surface 52. The 1 st light source LS1 is opposite to the 1 st side 53, and the 2 nd light source LS2 is opposite to the 2 nd side 54. Optical elements such as lenses for adjusting the width and angle of light from the light sources LS1 and LS2 may be further disposed between the 1 st light source LS1 and the 1 st side surface 53 and between the 2 nd light source LS2 and the 2 nd side surface 54.
The light guide plate LG includes: a central portion CP located between the 1 st side surface 53 and the 2 nd side surface 54 in the 2 nd direction Y; a1 st portion P1 located between the 1 st side 53 and the central portion CP; and a2 nd portion P2 located between the 2 nd side 54 and the central portion CP.
The central portion CP includes a center C in the 2 nd direction Y of the light guide plate LG. The 1 st portion P1 has a shape in which the thickness increases as going from the 1 st side 53 to the central portion CP. The 2 nd portion P2 has a shape in which the thickness increases as going from the 2 nd side surface 54 toward the central portion CP. In the example of fig. 2, the 2 nd face 52 is a plane. Therefore, the thickness variation of the light guide plate LG is caused by the shape variation of the 1 st surface 51. The light guide plate LG has a plane-symmetric shape with respect to, for example, an X-Z plane including the center C.
The 1 st light source LS1 irradiates the 1 st side surface 53 with diffused light having the 1 st irradiation direction DL1 as the center. The 2 nd light source LS2 irradiates diffused light having diffusion centered in the 2 nd irradiation direction DL2 to the 2 nd side surface 54. The irradiation directions DL1 and DL2 are, for example, parallel to the 2 nd direction Y, but may be inclined with respect to the 2 nd direction Y. As each of the light sources LS1 and LS2, for example, a light emitting element such as a semiconductor laser that emits polarized laser light can be used.
The 1 st light sources LS1 and the 2 nd light sources LS2 may include light emitting elements emitting light of different colors. For example, if the plurality of 1 st light sources LS1 and the plurality of 2 nd light sources LS2 include light emitting elements that emit red, green, and blue light, respectively, light of a mixed color (for example, white) of these colors can be obtained.
The display device 1 includes a prism sheet PS between the display panel 2 and the light guide plate LG. The display device 1 further includes a diffusion sheet DS (diffusion layer) between the prism sheet PS and the display panel 2. For example, the prism sheet PS includes a plurality of prisms Pa extending parallel to the 1 st direction X. These prisms Pa are formed on, for example, the lower surface (the surface opposite to the light guide plate LG) of the prism sheet PS and protrude toward the light guide plate LG. However, these prisms Pa may be formed on the upper surface (the surface facing the display panel 2) of the prism sheet PS.
In fig. 2, an example of an optical path of the light L1 emitted from the 1 st light source LS1 is shown by a solid line, and an example of an optical path of the light L2 emitted from the 2 nd light source LS2 is shown by a broken line. The light L1 emitted from the 1 st light source LS1 enters the light guide plate LG from the 1 st side surface 53, propagates through the light guide plate LG while being reflected by the surfaces 51 and 52, and is then emitted from the 2 nd surface 52 out of the total reflection condition of the 2 nd surface 52. The light L2 emitted from the 2 nd light source LS2 enters the light guide plate LG from the 2 nd side surface 54, propagates through the light guide plate LG while being reflected by the surfaces 51 and 52, and is then emitted from the 2 nd surface 52 out of the total reflection condition of the 2 nd surface 52. In this way, the 2 nd surface 52 corresponds to a light exit surface from which light exits. The display panel 2 displays an image using light emitted from the 2 nd surface 52.
The prism sheet PS converts the light emitted from the 2 nd surface 52 into light substantially parallel to the 3 rd direction Z. Here, the phrase "light substantially parallel to the 3 rd direction Z" includes not only light strictly parallel to the 3 rd direction Z but also light whose inclination angle with respect to the 3 rd direction Z is sufficiently smaller by the prism sheet PS than when emitted from the 2 nd surface 52. From the viewpoint of maintaining the polarization of the light from the light sources LS1 and LS2, the prism Pa is preferably formed on the lower surface of the prism sheet PS. The light passing through the prism sheet PS is diffused by the diffusion sheet DS and irradiated to the display panel 2. Even when the viewing angle of light passing through the prism sheet PS is narrow, the viewing angle can be widened by diffusing the light with the diffusion sheet DS.
When the light from the light sources LS1 and LS2 reaches the display panel 2 in a sufficiently polarized state, the 1 st polarizing plate PL1 may be omitted. In the case where the 1 st polarizing plate PL1 is omitted, a so-called transparent liquid crystal display device in which the background of the display device 1 can be seen through can be obtained by, for example, increasing the light transmittance of each of the substrates SUB1 and SUB 2.
Fig. 3 is a schematic plan view of the lighting device 3. In the example of the figure, 81 st light sources LS1 are arranged along the 1 st side surface 53, and 82 nd light sources LS2 are arranged along the 2 nd side surface 54, but the number of light sources LS1 and LS2 is not limited thereto. The intensity of light emitted from the 1 st light source LS1 is highest on the 1 st optical axis AX1, and the intensity of light emitted from the 2 nd light source LS2 is highest on the 2 nd optical axis AX 2.
As shown in the drawing, the light sources LS1 and LS2 are arranged in a staggered manner in the 2 nd direction Y. That is, the 1 st optical axis AX1 of the light emitted from the 1 st light source LS1 in the 1 st irradiation direction DL1 and the 2 nd optical axis AX2 of the light emitted from the 2 nd light source LS2 in the 2 nd irradiation direction DL2 are shifted from each other in the 1 st direction X. Further, the 1 st optical axis AX1 and the 2 nd optical axis AX2 may coincide in the 1 st direction X.
Fig. 4 is a schematic cross-sectional view of the light guide plate LG according to the present embodiment. The 1 st surface 51 of the light guide plate LG has the 1 st reflective structure 60 provided in the 1 st portion P1, the 2 nd reflective structure 70 provided in the 2 nd portion P2, and the 3 rd reflective structure 80 provided in the central portion CP. Each of the reflection structures 60, 70, and 80 is, for example, a prism that protrudes downward (in a direction opposite to the 3 rd direction Z).
In the Y-Z cross section, a straight line connecting the apexes of the 1 st reflective structures 60 is defined as a1 st virtual line VL1, a straight line connecting the apexes of the 2 nd reflective structures 70 is defined as a2 nd virtual line VL2, and a straight line connecting the apexes of the 3 rd reflective structures 80 is defined as a3 rd virtual line VL 3. The 1 st imaginary line VL1 is inclined at an angle θ 1 with respect to the 2 nd surface 52. The 2 nd imaginary line VL2 is inclined at an angle θ 2 with respect to the 2 nd face 52. The angles θ 1 and θ 2 are both acute angles. From the viewpoint of uniformizing the luminance distribution of the 2 nd surface 52, the angles θ 1 and θ 2 are preferably the same. However, the angles θ 1 and θ 2 may be different. The 3 rd imaginary line VL3 is parallel to the 2 nd surface 52, for example. Each 3 rd reflection structure 80 may be arranged such that the 3 rd virtual line VL3 is curved.
The light L1 from the 1 st light source LS1 is reflected by the 2 nd reflecting structure 70 and exits from the 2 nd surface 52 of the 2 nd segment P2. The light L2 from the 2 nd light source LS2 is reflected by the 1 st reflecting structure 60 and emitted from the 2 nd surface 52 of the 1 st segment P1. The light L1 and L2 are also reflected by the 3 rd reflecting structure 80 and exit from the 2 nd surface 52 of the central portion CP. By providing the central portion CP, luminance unevenness at the boundary of the 1 st part P1 and the 2 nd part P2 is suppressed.
In the illumination device 3 having the above configuration, the luminance distribution of the 2 nd surface 52 may be uneven in a stripe shape. Fig. 5 is a schematic plan view for explaining the luminance unevenness. This figure corresponds to a comparative example of the present embodiment, and shows a state in which light L1 from the 1 st light source LS1 enters the light guide plate LG from the 1 st side surface 53 and propagates through the light guide plate LG.
The light L1 widens in its width in the 1 st direction X as it travels in the 2 nd direction Y. The light L1 includes a plurality of stripes 100 as bright lines or dark lines. These streaks 100 are caused by minute irregularities in the 1 st side surface 53. In the present embodiment, since the 1 st light source LS1 is a point light source that emits laser light having high straightness, the light guide plate LG is incident from a narrow region of the 1 st side surface 53. Therefore, the first side surface 53 is particularly susceptible to the minute unevenness. The similar stripe 100 may be generated also in the light L2 from the 2 nd light source LS2 due to the influence of the minute unevenness of the 2 nd side surface 54. If the luminance unevenness due to these stripes 100 occurs, the display quality of the display device 1 may be degraded.
The method of processing the mold for molding the light guide plate LG is considered to be one of the causes of the minute irregularities generated on the 1 st side surface 53 and the 2 nd side surface 54. Fig. 6 is a view schematically showing a method of processing the surface 200 corresponding to the 1 st side surface 53 in the mold for the light guide plate LG.
The 1 st side surface 53 and the 2 nd side surface 54 are preferably sufficiently smooth to allow light to enter satisfactorily. The surface 200 is thus mirror finished. For example, in the mirror finishing of the surface 200, the tool 300 having an arc-shaped tip abutting on the surface to be machined is used. The tool 300 is relatively moved in the longitudinal direction of the surface 200 (direction corresponding to the 1 st direction X) to cut the surface 200. This operation is performed a plurality of times while gradually shifting the relative positions of the tool 300 and the surface 200 in the thickness direction of the surface 200 (the direction corresponding to the 3 rd direction Z). Thereby, the entire surface 200 is mirror finished.
Fig. 7 is a schematic cross-sectional view of a mold 210 (block) having a surface 200. On the surface 200, minute irregularities corresponding to the overlap of the machining region when cutting with the tool 300 while shifting in the thickness direction as shown in fig. 6 are formed. The 1 st side surface 53 of the light guide plate LG molded by using the mold 210 has irregularities corresponding to the shape of the surface 200.
If the irregularities of the 1 st side surface 53 are formed at a pitch smaller than the light incident region of the light from the 1 st light source LS1, the light incident region overlaps with the irregularities, and thus the luminance unevenness shown in fig. 5 may occur. The 2 nd light source LS2 and the 2 nd side surface 54 may have uneven brightness for the same reason.
Next, a method of processing the surface 200 and the shape of the light guide plate LG in the present embodiment for suppressing such luminance unevenness will be described. Fig. 8 is a diagram schematically illustrating a method of processing the surface 200 in the present embodiment. The ellipse of the dotted line in the surface 200 indicates the position of the light incident region RA irradiated with light from the 1 st light source LS1 in the 1 st side surface 53 of the light guide plate LG molded by the mold having the surface 200.
In the present embodiment, the surface 200 is cut by relatively moving the cutter 300 in the thickness direction (the direction corresponding to the 3 rd direction Z). Such cutting is performed once for each position of each light entrance region RA. Thereby, the surface 200 is locally smoothed. The tool 300 has a size capable of cutting a range including the light entrance area RA in one movement.
Fig. 9 is a schematic side view of a light guide plate LG molded by a mold having a surface 200 processed by the method shown in fig. 8. The 1 st side 53 has a plurality of 1 st regions a1 and a plurality of 2 nd regions a 2. The 1 st region a1 corresponds to a smoothed portion of the surface 200 of the mold. Region 2 a2 corresponds to an area of the surface 200 of the mold that is not smoothed.
The 1 st region a1 and the 2 nd region a2 are alternately arranged in the 1 st direction X. In the example of fig. 9, the 2 nd regions a2 are located at both ends of the 1 st side surface 53 in the 1 st direction X, but the 1 st regions a1 may be located at both ends.
The 1 st region a1 and the 2 nd region a2 are formed in the 3 rd direction Z in a range from the end on the 1 st surface 51 side to the end on the 2 nd surface 52 side. In the example of fig. 9, the width in the 1 st direction X of the 1 st region a1 is smaller than the width in the 1 st direction X of the 2 nd region a 2. However, the width of the 1 st region a1 may be equal to or greater than the width of the 2 nd region a 2.
The 2 nd side surface 54 can also be formed by the same method as the 1 st side surface 53. In this case, as shown by a parenthesized reference numeral in fig. 9, A3 rd region A3 identical to the 1 st region a1 and a4 th region a4 identical to the 2 nd region a2 are formed at the 2 nd side 54. In the case where the plurality of 1 st light sources LS1 and the plurality of 2 nd light sources LS2 are arranged to be shifted in the 1 st direction X as shown in fig. 3, the 1 st region a1 and the 3 rd region A3 may be shifted in the 1 st direction X.
In such a light guide plate LG, the 1 st light sources LS1 are arranged so that the light incident region RA of the light L1 is included in the 1 st region a1, and the 2 nd light sources LS2 are arranged so that the light incident region RA of the light L2 is included in the 3 rd region A3. By such a manufacturing method, the illumination device 3 of the present embodiment can be obtained. The display device 1 of the present embodiment can be obtained by disposing the illumination device 3 in opposition to the display panel 2 and the like shown in fig. 1.
Fig. 10 is a schematic plan view showing an example of the structure of the lighting device 3 in the vicinity of the 1 st side surface 53. The light L1 of the 1 st light source LS1 is irradiated to the 1 st region a1, and is not irradiated to the 2 nd region a 2. Similarly, the light L2 of the 2 nd light source LS2 is irradiated to the 3 rd region A3, but is not irradiated to the 4 th region a 4.
For example, as shown in fig. 10, the 1 st region a1 may be a curved surface protruding toward the 1 st light source LS1 side from the 2 nd region a 2. In this case, the light entrance region RA may be located in the 1 st region a1 at the portion that protrudes most toward the 1 st light source LS1 side. In the example of fig. 10, the light emitting surface of the 1 st light source LS1 is in contact with the 1 st region a 1. However, a gap may be provided between the 1 st light source LS1 and the 1 st region a 1. The 2 nd area a2 is, for example, a flat surface, and may have at least a part of a curved surface.
The shape of the 1 st area a1 is not limited to the curved surface shown in fig. 10. Fig. 11 is a schematic plan view showing another example of the structure of the lighting device 3 in the vicinity of the 1 st side surface 53. In the example of the figure, the 1 st region a1 is a curved surface recessed compared to the 2 nd region a 2.
In addition to the shapes shown in fig. 10 and 11, various shapes can be applied to the 1 st region a1 and the 2 nd region a 2. The same structure as that of the 1 st region a1 and the 2 nd region a2 can be applied to the 3 rd region A3 and the 4 th region a4 of the 2 nd side surface 54.
The 1 st region a1 corresponds to the portion of the surface 200 of the mold that was smoothed by the cutter 300 described above. Therefore, the surface roughness of the 1 st region a1 is less than that of the 2 nd region a 2. Further, the surface 200 is smoothed by one cutting by the cutter 300. Therefore, the unevenness shown in fig. 7 is not easily formed on the 1 st side surface 53. When light from the 1 st light source LS1 is incident on the 1 st region a1, the luminance unevenness described with reference to fig. 5 is suppressed.
Likewise, the surface roughness of the 3 rd region A3 is less than the surface roughness of the 4 th region a 4. In addition, when the surface of the mold corresponding to the 2 nd side surface 54 is processed by the method described with reference to fig. 8, the luminance unevenness in the light from the 2 nd light source LS2 is suppressed.
The inventors of the present application fabricated the light guide plate LG using a mold having a surface 200 processed by the method shown in fig. 8, and obtained a three-dimensional profile of the 1 st side surface 53 in the light guide plate LG. Using the profile, the arithmetic average roughness Ra and the maximum height roughness Rz in the 3 rd direction Z were obtained for the 1 st region a1 and the 2 nd region a2, respectively. Here, the arithmetic average roughness Ra is a value obtained by summing up absolute values of deviations from an average line to a profile curve of a reference length extracted from the profile and averaging the sum of the absolute values with the reference length. The maximum height roughness Rz is a value obtained by adding the maximum value of the peak height and the maximum value of the valley depth to the profile curve of the reference length.
The arithmetic average roughness Ra in the 1 st region A1 was 0.001. mu.m, and the maximum height roughness Rz in the 1 st region A1 was 0.005. mu.m. On the other hand, the arithmetic average roughness Ra in the 2 nd region A2 was 0.010 μm, and the maximum height roughness Rz was 0.048 μm. As described above, the difference of about 10 times between the arithmetic average roughness Ra and the maximum height roughness Rz occurs in the molded article in both the region smoothed by the tool 300 and the region not smoothed by the tool 300.
When the 1 st region a1 has the arithmetic average roughness Ra and the maximum height roughness Rz, the luminance unevenness shown in fig. 5 is favorably reduced. On the other hand, when the laser light is made incident on the 2 nd region a2, brightness unevenness occurs. From the above description, the arithmetic average roughness Ra in the 1 st region a1 is preferably at least less than 0.010 μm, more preferably 0.005 μm or less, and most preferably 0.001 μm or less. The maximum height roughness Rz in the 1 st region a1 is preferably at least less than 0.048 μm, more preferably 0.020 μm or less, and most preferably 0.005 μm or less.
Here, the roughness of the 1 st region a1 and the roughness of the 2 nd region a2 are compared based on the arithmetic average roughness Ra and the maximum height roughness Rz, but other parameters relating to the roughness may be used for the comparison. As other parameters, for example, an arithmetic average height Pa, an arithmetic average waviness Wa, a maximum height Pz, a maximum height waviness Wz, and the like of the profile curve can be used. Of these parameters, it is also preferable that the 1 st region a1 be smaller than the 2 nd region a 2. The roughness of the 3 rd region A3 and the 4 th region a4 of the 2 nd side surface 54 can be determined in the same manner as the 1 st region a1 and the 2 nd region a 2.
Fig. 12 is a schematic plan view of the 1 st region a 1. The 1 st region a1 has a width W1 in the 1 st direction X and a width W2 in the 3 rd direction Z. The light entrance region RA has an elliptical shape as described above, and has a width WL in the 1 st direction X and a width WS in the 3 rd direction Z. For example, the width WL corresponds to the length of the major axis of the light entrance region RA, and the width WS corresponds to the length of the minor axis. As shown in fig. 9, in the structure in which the 1 st region a1 is formed from the 1 st surface 51-side end to the 2 nd surface 52-side end in the 1 st side surface 53, the width W2 corresponds to the thickness of the light guide plate LG at the 1 st side surface 53. The width W2 in this case is, for example, 1mm or more.
In order to make all of the light-incident regions RA fall within the 1 st region A1, it is necessary to make the width W1 equal to or greater than the width WL (W1. gtoreq.WL) and the width W2 equal to or greater than the width WS (W2. gtoreq.WS). The widths WL and WS are mainly determined by the specification and arrangement of the 1 st light source LS 1.
Fig. 13 is a schematic plan view showing an example of a configuration applicable to the 1 st light source LS 1. Fig. 14 is a schematic side view of the 1 st light source LS1 shown in fig. 13. The 1 st light source LS1 includes a light emitting point O that emits light L1 as laser light and a light emitting surface SF that is a surface from which light L1 is emitted. A distance T exists between the light emission point O and the light emission surface SF.
As shown in fig. 13, the half-width-at-half-maximum (FWHM) of the light L1 in the 1 st direction X is expanded by an angle θ X. In addition, as shown in fig. 14, the half-peak width of the light L1 in the 3 rd direction Z is expanded by an angle θ Z. A half-width of the light L1 in the 1 st direction X on the light emitting surface SF is defined as Wx, and a half-width of the light L1 in the 3 rd direction Z on the light emitting surface SF is defined as Wz.
In addition, the following specifications are assumed to be used as the 1 st light source LS 1.
[1]T＝0.83mm、θx＝23°、θz＝13°
[2]T＝0.85mm、θx＝25°、θz＝9°
[3]T＝0.85mm、θx＝25°、θz＝7.5°
In the case of [1], the width Wx is 0.352mm and the width Wz is 0.191 mm. In the case of [2], the width Wx was 0.396mm and the width Wz was 0.134 mm. In the case of [3], the width Wx was 0.396mm and the width Wz was 0.112 mm.
When the light-emitting surface SF is disposed in surface contact with the 1 st side surface 53 of the light guide plate LG, the width WL of the light entrance region RA is equal to the width Wx, and the width WS is equal to the width Wz. Therefore, the width W1 of the 1 st region a1 is preferably at least larger than the value of the width Wx of the 1 st light source LS1 of [1] to [3], for example, 0.400mm or more. The width W2 of the 1 st region a1 is preferably at least greater than the value of the width Wz of the 1 st light source LS1 in the above-described [1] to [3], and is, for example, 0.200mm or more.
Fig. 15 is a schematic cross-sectional view showing another example of the arrangement of the 1 st light source LS 1. In the example of the figure, the 1 st light source LS1 is held by a holder 400. The 1 st light source LS1 is inclined with respect to the 2 nd direction Y and the 3 rd direction Z. An acute angle formed by the 1 st optical axis AX1 (the 1 st irradiation direction DL1) of the light emitted from the 1 st light source LS1 and the 2 nd direction Y is defined as θ LD. In addition, a distance between the light emitting surface SF and the 1 st side surface 53 on the 1 st optical axis AX1 is defined as D.
Here, a case is assumed where the angle θ LD is 38 ° and the distance D is 0.394 mm. When the 1 st light source LS1 described in [1] above is used, the width Wx of the light incident region RA is 0.520mm, and the width Wz is 0.282 mm. When the 1 st light source LS1 described in [2] above is used, the width Wx of the light incident region RA is 0.581mm, and the width Wz is 0.197 mm. When the 1 st light source LS1 described in [3] above is used, the width Wx of the light entrance region RA is 0.581mm, and the width Wz is 0.164 mm.
In the case of applying the structure of fig. 15, the width W1 of the 1 st region a1 is preferably at least larger than the value of the width Wx of the 1 st light source LS1 of [1] to [3], for example, 0.600mm or more. The width W2 of the 1 st region a1 is preferably larger than the value of the width Wz of the 1 st light source LS1 of [1] to [3], for example, by 0.300mm or more.
The arrangement of the 2 nd light source LS2 and the size of the 3 rd region A3 can be determined in the same manner as the 1 st light source LS1 and the 1 st region a 1. The 1 st region a1 and the 3 rd region A3 may be the same size or different sizes.
As described above, in the present embodiment, the 1 st region a1 having a small surface roughness is provided on the 1 st side surface 53 of the light guide plate LG, and the 1 st region a1 is irradiated with the light L1 of the 1 st light source LS 1. This allows the light L1 to be appropriately incident on the light guide plate LG, thereby suppressing the luminance unevenness of the 2 nd surface 52 as the light output surface.
In addition, the 1 st side 53 has a2 nd region a2 having a surface roughness greater than the 1 st region a 1. If the entire 1 st side surface 53 is finished to a mirror surface with a small surface roughness, the processing described with reference to fig. 6 needs to be performed on the mold. In this case, the minute unevenness shown in fig. 7 is formed on the 1 st side surface 53, and the light incident region RA of the light L1 overlaps with the unevenness, and the luminance unevenness described with reference to fig. 5 may occur. On the other hand, if the 1 st region a1 having a small surface roughness is locally provided at a necessary portion of the 1 st side surface 53, a mold can be processed by the method described with reference to fig. 8, for example. In this case, the minute unevenness shown in fig. 7 is less likely to occur, and light L1 can be irradiated onto a smooth surface.
The 2 nd side 54 of the light guide plate LG also has the 3 rd region A3 having a small surface roughness and the 4 th region a4 having a large surface roughness, and therefore the same effects can be obtained.
In addition, according to the present embodiment, the effects mentioned in the present embodiment or other various effects can be obtained.
All of the illumination device, the display device, and the method for manufacturing the illumination device, which can be implemented by those skilled in the art by appropriately performing design changes based on the illumination device and the display device described above as the embodiments of the present invention, are within the scope of the present invention as long as the gist of the present invention is included.
It should be understood that various modifications can be conceived by those skilled in the art within the scope of the idea of the present invention, and that these modifications also fall within the scope of the present invention. For example, a person skilled in the art can add, delete, or modify the design of components or add, omit, or modify the conditions of the process as appropriate for the above-described embodiment, and the scope of the present invention is included as long as the gist of the present invention is achieved.
It is to be understood that the other operational effects of the embodiments described above are clearly known from the description of the present specification or can be appropriately conceived by those skilled in the art, and are the effects of the present invention.
Claims (10)
1. An illumination device, comprising:
a1 st light source emitting laser light; and
a light guide plate having a1 st side surface to which light from the 1 st light source is applied, a2 nd side surface opposite to the 1 st side surface, a1 st surface to reflect light incident from the 1 st side surface, and a2 nd surface to which light reflected by the 1 st surface is emitted,
the 1 st side surface has a1 st region including a light incident region to which light from the 1 st light source is irradiated and a2 nd region to which light from the 1 st light source is not irradiated,
the surface roughness of the 1 st region is less than the surface roughness of the 2 nd region.
2. The lighting device of claim 1,
a plurality of the 1 st light sources arranged along the 1 st side surface,
the 1 st side surface has a plurality of the 2 nd regions and a plurality of the 1 st regions corresponding to a plurality of the 1 st light sources, respectively,
the 1 st regions and the 2 nd regions are alternately arranged in the arrangement direction of the 1 st light source.
3. The lighting device of claim 1,
the 1 st region is a curved surface,
the 2 nd region is a plane.
4. The lighting device of claim 1,
the 1 st region is more protruded than the 2 nd region.
5. The lighting device of claim 1,
the 1 st region is more recessed than the 2 nd region.
6. The lighting device of claim 1,
further comprises a2 nd light source for irradiating the 2 nd side surface with laser light,
the 2 nd side surface has a3 rd region including a light incident region to which light from the 2 nd light source is irradiated and a4 th region to which light from the 2 nd light source is not irradiated,
the surface roughness of the 3 rd region is less than the surface roughness of the 4 th region.
7. The lighting device of claim 1,
the light guide plate has:
a central portion located between the 1 st side and the 2 nd side;
a1 st portion between the 1 st side and the central portion, the 1 st portion increasing in thickness as the central portion approaches from the 1 st side; and
a2 nd portion between the 2 nd side and the central portion, the 2 nd portion increasing in thickness as the central portion approaches from the 2 nd side.
8. A display device, comprising:
the lighting device of any one of claims 1 to 7; and
and a display panel which is opposed to the 2 nd surface and displays an image using light emitted from the 2 nd surface.
9. A method of manufacturing an illumination device, the illumination device comprising:
a1 st light source emitting laser light; and
a light guide plate having a1 st side surface to which light from the 1 st light source is applied, a2 nd side surface opposite to the 1 st side surface, a1 st surface to reflect light incident from the 1 st side surface, and a2 nd surface to which light reflected by the 1 st surface is emitted,
the method of manufacturing the lighting device is characterized in that,
partially smoothing a surface of the mold of the light guide plate corresponding to the 1 st side surface,
forming a1 st region corresponding to a portion of the surface that is smoothed and a2 nd region corresponding to a portion that is not smoothed on the 1 st side surface by shaping the light guide plate using the mold,
the 1 st light source is disposed so that a light incident region of light from the 1 st light source is included in the 1 st region.
10. The method of manufacturing a lighting device according to claim 9,
the smoothed portion is formed on the surface by cutting the surface of the mold once in a direction corresponding to a thickness direction of the light guide plate using a cutter having an arc-shaped tip.
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| Application Number | Priority Date | Filing Date | Title |
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| JP2019016899A JP2020126717A (en) | 2019-02-01 | 2019-02-01 | Illuminating device, display device, and manufacturing method for illuminating device |
| JP2019-016899 | 2019-02-01 |
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| CN111522174A true CN111522174A (en) | 2020-08-11 |
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| CN201911236534.3A Pending CN111522174A (en) | 2019-02-01 | 2019-12-05 | Illumination device, display device, and method for manufacturing illumination device |
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| JP2020126717A (en) | 2020-08-20 |
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