JP2020113427A - Luminaire and display device - Google Patents

Abstract

To provide a luminaire which can radiate light of favorable luminance distribution from an emission surface of a light guide plate, and to provide a display device including the luminaire.SOLUTION: A luminaire includes: first and second light sources for emitting laser light; and a light guide plate having first and second end parts to which light from the light sources are radiated respectively, a first surface for reflecting incident light and a second surface from which the light emits. The light guide plate includes: a central portion; a first portion in which the light from the second light source emits with high luminance from the second surface; and a second portion in which the light from the first light source emits with high luminance from the second surface. The central portion has a luminance inclination characteristic in which the luminance when the light from the first light source emits from the second surface increases from a first end part side toward a second end part side sequentially, and the luminance when the light from the second light source emits from the second surface increases from the second end part side toward the first end part side sequentially.SELECTED DRAWING: Figure 8

Description

Embodiments of the present invention relate to a lighting device and a display device.

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 that illuminates the display panel. The illumination device includes a light source that emits light and a light guide plate that is irradiated with light from the light source. The light from the light source enters the light guide plate from the end portion of the light guide plate, propagates in the light guide plate, and is emitted from the emission surface corresponding to one main surface of the light guide plate. For example, as disclosed in Patent Document 1, there is also known an illuminating device in which light sources are arranged near both ends of a light guide plate.

Further, as disclosed in, for example, Patent Document 2, there is proposed an illuminating device in which light sources that emit laser light are arranged near both ends of a light guide plate. In such a configuration, the light from one light source mainly exits from the region of the light guide plate near the other light source.

JP, 2015-41439, A JP, 2018-45990, A

As described above, in the illumination device using the light source that emits the laser light, the brightness of the light emitted from the light source from the light guide plate is greatly different between the area near the light source and the area far from the light source. Therefore, when the positional relationship between the region where the light from one light source is strongly emitted and the region where the light from the other light source is strongly emitted is deviated, a dark line or a bright line may occur in the central portion of the light guide plate.

An object of the present invention is to provide an illuminating device capable of irradiating light having a good luminance distribution from the exit surface of the light guide plate, and a display device including the illuminating device.

An illumination device according to an embodiment includes a first light source and a second light source that emit laser light, a first end portion that is irradiated with light from the first light source, and a first light source that is irradiated with light from the second light source. A light guide plate having two end portions, a first surface that reflects the light incident from the first end portion and the second end portion, and a second surface that emits the light reflected by the first surface. I have it. The light guide plate is located between the first end portion and the second end portion, and between the first end portion and the center portion, and the light from the second light source is the first portion. A first portion that is emitted from the second surface with higher brightness than the light from one light source, and is located between the second end portion and the central portion, and the light from the first light source is emitted from the second light source. And a second portion that is emitted from the second surface with a higher brightness than that of the second light. In the central portion, the brightness when the light from the first light source is emitted from the second surface gradually increases from the first end side toward the second end side, and the second end From the side to the first end side, the brightness gradient characteristic is such that the brightness when the light from the second light source is emitted from the second surface is sequentially increased.

A display device according to an embodiment includes the lighting device and a display panel that faces the second surface and displays an image using light emitted from the second surface.

FIG. 1 is a perspective view showing a schematic configuration of the display device according to the first embodiment. FIG. 2 is a schematic cross-sectional view of the display device according to the first embodiment. FIG. 3 is a schematic plan view of the lighting device according to the first embodiment. FIG. 4 is a plan view for explaining the relationship between the light emitted by the first light source and the luminance of the second surface in the lighting device according to the first embodiment. FIG. 5 is a graph showing an example of the brightness of light emitted from the light guide plate according to the first embodiment. FIG. 6 is a graph showing another example of the brightness of light emitted from the light guide plate according to the first embodiment. FIG. 7 is a plan view of the second surface schematically showing the luminance distribution of the combined light shown in FIG. FIG. 8 is a schematic cross-sectional view of the light guide plate according to the first embodiment. FIG. 9 is an enlarged cross-sectional view of the central portion of the light guide plate according to the first embodiment. FIG. 10 is an enlarged cross-sectional view of the first portion of the light guide plate according to the first embodiment. FIG. 11 is an enlarged cross-sectional view of the second portion of the light guide plate according to the first embodiment. FIG. 12 is an enlarged cross-sectional view of the central portion of the light guide plate according to the second embodiment. FIG. 13: is sectional drawing which shows an example of the illuminating device which concerns on 3rd Embodiment. FIG. 14: is sectional drawing which shows the other example of the illuminating device which concerns on 3rd Embodiment. FIG. 15 is a sectional view showing still another example of the illumination device according to the third embodiment. FIG. 16 is a schematic cross-sectional view of the lighting device according to the fourth embodiment. FIG. 17 is a schematic cross-sectional view of the lighting device according to the fifth embodiment.

Some embodiments will be described with reference to the drawings.
It should be noted that the disclosure is merely an example, and a person having ordinary skill in the art can easily think of appropriate modifications while keeping the gist of the invention, and of course fall within the scope of the present invention. Further, although the drawings may be schematically illustrated in comparison with an actual mode in order to make the description clearer, they are merely examples and do not limit the interpretation of the present invention. In each drawing, the same or similar elements arranged consecutively may be omitted from the reference numerals. Further, in the present specification and the drawings, components having the same or similar functions as those described above with respect to the already-existing drawings are designated by the same reference numerals, and redundant detailed description may be omitted.

In each of the embodiments, a transmissive liquid crystal display device is disclosed as an example of the display device. In addition, a backlight of a liquid crystal display device is disclosed as an example of a lighting device. However, each embodiment does not prevent application of the individual technical idea disclosed in each embodiment to other types of display devices and lighting devices. Other types of display devices include, for example, a liquid crystal display device having a reflection type function of reflecting external light and utilizing the reflected light for display in addition to a transmission type function, and a Micro Electro Mechanical System (MEMS). A display device or the like having a mechanical display panel in which the shutter functions as an optical element is assumed. As another type of illumination device, for example, a front light arranged in front of the display device is assumed. Further, the lighting device may be used for a purpose different from the lighting of the display device.

[First Embodiment]
FIG. 1 is a perspective view showing a schematic configuration of a display device 1 according to the first embodiment. The display device 1 can be used in various devices such as a smartphone, a tablet terminal, a mobile phone terminal, a personal computer, a television receiver, an in-vehicle device, a game machine, and a wearable terminal.

The display device 1 includes a display panel 2, a lighting device 3 that is a backlight, a drive IC chip 4 (controller) that drives the display panel 2, and a flexible circuit board that transmits a control signal to the display panel 2 and the lighting device 3. It is provided with FPC1 and FPC2. For example, the flexible circuit boards FPC1 and FPC2 are connected to a control module that controls the operations of the display panel 2 and the lighting device 3.

The display panel 2 includes a first substrate SUB1 (array substrate) and a second substrate SUB2 (opposing substrate) facing the first substrate SUB1. The display panel 2 has a display area DA for displaying an image. The display panel 2 includes, for example, a plurality of pixels PX arranged in a matrix in the display area DA.

The lighting device 3 includes a first light source LS1, a second light source LS2, and a light guide plate LG facing the first substrate SUB1. The first light source LS1 faces one side surface of the light guide plate LG, and the second light source LS2 faces the other side surface of the light guide plate LG. Although each of the light sources LS1 and LS2 is shown in FIG. 1 one by one, actually, a plurality of first light sources LS1 and a plurality of second light sources LS2 are provided (see FIG. 3).

As shown in FIG. 1, a first direction X, a second direction Y and a third direction Z are defined. The respective directions X, Y, Z are, for example, orthogonal to each other. In the present disclosure, viewing the display device 1 from a direction parallel to the third direction Z is referred to as a plan view. In addition, to see a cross section of the display device 1 parallel to the XZ plane is referred to as a cross sectional view. In the example of FIG. 1, each of the substrates SUB1 and SUB2 and the light guide plate LG has a long side along the first direction X and a short side along the second direction Y, and has a rectangular shape in plan view. .. However, the shape of each of the substrates SUB1 and SUB2 and the light guide plate LG is not limited to this, and the shape in plan view may be another shape such as a square or a circle.

FIG. 2 is a schematic cross-sectional view of the display device 1 parallel to the XZ plane. The display panel 2 further includes a seal material SL, a liquid crystal layer LC, a first polarizing plate PL1, and a second polarizing plate PL2. The substrates SUB1 and SUB2 are attached to each other with a sealing material SL. The liquid crystal layer LC is enclosed between the seal material SL and the substrates SUB1 and SUB2.

The first polarizing plate PL1 is attached to the lower surface (surface facing the light guide plate LG) of the first substrate SUB1. The second polarizing plate PL2 is attached to the upper surface of the second substrate SUB2 (the surface not facing the first substrate SUB1). The polarization axes of the polarizing plates PL1 and PL2 are, for example, orthogonal to each other.

The light guide plate LG has a first surface 51, a second surface 52 opposite to the first surface 51, a first end portion 53, and a second end portion 54 opposite to the first end portion 53. ing. The display panel 2 faces the second surface 52. The first light source LS1 faces the first end portion 53, and the second light source LS2 faces the second end portion 54. Between the first light source LS1 and the first end portion 53 and between the second light source LS2 and the second end portion 54, an optical element such as a lens for adjusting the width or angle of the light from each of the light sources LS1 and LS2 is provided. It may be further arranged.

The light guide plate LG includes a central portion CP located between the first end portion 53 and the second end portion 54 in the first direction X, and a first portion P1 located between the first end portion 53 and the central portion CP. , And a second portion P2 located between the second end portion 54 and the central portion CP.

The central portion CP includes the center C of the light guide plate LG in the first direction X. The first portion P1 has a shape in which the thickness increases from the first end portion 53 toward the central portion CP. The second portion P2 has a shape in which the thickness increases from the second end portion 54 toward the central portion CP. In the example of FIG. 2, the second surface 52 is a flat surface. Therefore, the change in the thickness of the light guide plate LG is caused by the change in the shape of the first surface 51. The light guide plate LG has, for example, a plane symmetric shape with respect to the YZ plane including the center C. In the example of FIG. 2, the first surface 51 and the second surface 52 are parallel to each other in the central portion CP, but actually the first surface 51 has a shape as shown in FIG. 8 described later. Further, the second surface 52 is provided with a reflecting structure for reflecting the light from each of the light sources LS1 and LS2.

The first light source LS1 irradiates the first end portion 53 with diffused light having a spread centered on the first irradiation direction DL1. The second light source LS2 irradiates the second end portion 54 with diffused light having a spread centered on the second irradiation direction DL2. The irradiation directions DL1 and DL2 are, for example, opposite directions and are parallel to the first direction X. As the light emitting element of each of the light sources LS1 and LS2, for example, a laser light source such as a semiconductor laser that emits polarized laser light can be used.

Each of the light sources LS1 and LS2 may include a plurality of light emitting elements that emit light of different colors. For example, if each of the light sources LS1 and LS2 includes three light emitting elements that emit red, green, and blue light, respectively, it is possible to obtain light of a mixed color (for example, white) of these colors.

The display device 1 includes a prism sheet PS between the display panel 2 and the light guide plate LG. Further, the display device 1 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 large number of prisms Pa extending parallel to the second direction Y. These prisms Pa are formed, for example, on the lower surface of the prism sheet PS (the surface facing the light guide plate LG) 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 the optical path of the light L1 emitted by the first light source LS1 is shown by a solid line, and an example of the optical path of the light L2 emitted by the second light source LS2 is shown by a broken line. The light L1 emitted from the first light source LS1 enters the light guide plate LG from the first end portion 53, propagates through the light guide plate LG while being reflected by the surfaces 51 and 52, and eventually deviates from the total reflection condition of the second surface 52. And is emitted from the second surface 52. The light L2 emitted from the second light source LS2 enters the light guide plate LG from the second end portion 54, propagates through the light guide plate LG while being reflected by the surfaces 51 and 52, and eventually deviates from the total reflection condition of the second surface 52. And is emitted from the second surface 52. In this way, the second surface 52 corresponds to the emission surface from which light is emitted. The display panel 2 displays an image using the light emitted from the second surface 52.

The prism sheet PS converts the light emitted from the second surface 52 into light substantially parallel to the third direction Z. Here, the “light substantially parallel to the third direction Z” is not only light that is strictly parallel to the third direction Z, but also has an inclination with respect to the third direction Z when compared with when it is emitted from the second surface 52. And includes light that has been converted sufficiently small by the prism sheet PS. From the viewpoint of maintaining the polarization of the light from each of the light sources LS1 and LS2, the prism Pa is preferably formed on the lower surface of the prism sheet PS. The light that has passed through the prism sheet PS is diffused by the diffusion sheet DS and applied to the display panel 2. Even if the viewing angle of light that has passed through the prism sheet PS is narrow, the viewing angle can be widened by diffusing this light with the diffusion sheet DS.

If the light from each of the light sources LS1 and LS2 reaches the display panel 2 in a sufficiently polarized state, the first polarizing plate PL1 may be omitted. When the first polarizing plate PL1 is omitted, for example, the so-called transparent liquid crystal display device in which the background of the display device 1 can be seen through can be obtained by increasing the translucency of each of the substrates SUB1 and SUB2.

FIG. 3 is a schematic plan view of the lighting device 3. In the example of this figure, eight first light sources LS1 are arranged along the first end portion 53 and eight second light sources LS2 are arranged along the second end portion 54, but the light sources LS1 and LS2 are arranged. Is not limited to this. The intensity of the light emitted from the first light source LS1 is the highest on the first optical axis AX1, and the intensity of the light emitted from the second light source LS2 is the highest on the second optical axis AX2.

The light sources LS1 and LS2 are arranged in a staggered manner in the second direction Y, as illustrated. That is, the first optical axis AX1 of the light emitted from the first light source LS1 in the first irradiation direction DL1 and the second optical axis AX2 of the light emitted from the second light source LS2 in the second irradiation direction DL2 are in the second direction Y. They are offset from each other. The first optical axis AX1 and the second optical axis AX2 may be aligned in the second direction Y.

FIG. 4 is a plan view for explaining the relationship between the light emitted by the first light source LS1 and the brightness of the second surface 52. Here, three first light sources LS1 and light emitted by these are illustrated. In the present embodiment, the light emitted by the first light source LS1 is laser light, and therefore has excellent directivity and convergence. Therefore, when viewed in the XY plane, the spread in the second direction Y is smaller than that of a general LED. Therefore, in the first portion P1, there is a region NA through which the light from the first light source LS1 does not pass. On the other hand, in the central portion CP and the second portion P2, the light passes through the entire area.

Light from the first light source LS1 is less likely to deviate from the total reflection condition of the second surface 52 in the first portion P1 and is not emitted from the second surface 52 so much. On the other hand, this light is likely to deviate from the total reflection condition of the second surface 52 in the second portion P2, and a large amount of this light is emitted from the second surface 52. Further, this light is emitted from the second surface 52 with lower brightness in the central portion CP than in the second portion P2.

The light from the second light source LS2 is not emitted so much from the second surface 52 in the second portion P2, and is largely emitted from the second surface 52 in the first portion P1. As described above, the first light source LS1 mainly plays a role of lighting the second surface 52 of the second portion P2, and the second light source LS2 mainly plays a role of lighting the second surface 52 of the first portion P1.

5 and 6 are graphs showing an example of the brightness (BR) of the light emitted from the second surface 52. In the first portion P1, the light L1 from the first light source LS1 has extremely low brightness. The brightness of the light L1 sharply increases in the vicinity of the center C and becomes high in the second portion P2. On the contrary, the light L2 from the second light source LS2 has low brightness in the second portion P2, sharply rises in the vicinity of the center C, and has high brightness in the first portion P1. Thus, in the first portion P1, the light L2 from the second light source LS2 is emitted from the second surface 52 with higher brightness than the light L1 from the first light source LS1. In the second portion P2, the light L1 from the first light source LS1 is emitted from the second surface 52 with higher brightness than the light L2 from the second light source LS2.

Ideally, the brightness of the combined light L of the lights L1 and L2 is constant over the first portion P1, the second portion P2, and the central portion CP, as shown in FIG. However, when the brightness changes of the lights L1 and L2 do not match in the central portion CP, the brightness of the combined light L becomes nonuniform in the central portion CP. FIG. 6 shows an example in which both the lights L1 and L2 are insufficient at the center C, and the brightness of the combined light L sharply decreases at the center C and in the vicinity thereof. As another example, when the overlap of the brightness of the lights L1 and L2 is too large at the center C, the brightness of the combined light L sharply increases at the center C and in the vicinity thereof.

FIG. 7 is a plan view of the second surface 52 schematically showing the luminance distribution of the combined light shown in FIG. Since the brightness is lowered at the center C, a dark line DL along the center C is generated on the second surface 52. When the brightness of the combined light L sharply rises in and around the center C, a bright line is generated instead of the dark line DL.

If the brightness of the second surface 52 becomes non-uniform due to these dark lines and bright lines, the image quality of the display panel PNL may also deteriorate. In the present embodiment, the light guide plate LG has a configuration capable of suppressing such dark lines and bright lines. Hereinafter, details of the light guide plate LG will be described.

FIG. 8 is a schematic sectional view of the light guide plate LG in the present embodiment. The first surface 51 of the light guide plate LG has a first reflection structure 60 provided in the central portion CP, a second reflection structure 70 provided in the first portion P1, and a third reflection structure provided in the second portion P2. Structure 80. Each of the reflecting structures 60, 70, 80 is, for example, a prism protruding downward (a direction opposite to the third direction Z).

A straight line connecting the vertices of the second reflecting structure 70 is defined as a first virtual line VL1, and a straight line connecting the vertices of the third reflecting structure 80 is defined as a second virtual line VL2. The first virtual line VL1 is inclined at an angle θ1 with respect to the second surface 52. The second virtual line VL2 is inclined at an angle θ2 with respect to the second surface 52. The angles θ1 and θ2 are both acute angles. From the viewpoint of making the luminance distribution of the second surface 52 uniform, it is preferable that the angles θ1 and θ2 are the same. However, the angles θ1 and θ2 may be different. Each first reflection structure 60 in the central portion CP is located, for example, on the second surface 52 side with respect to each virtual line VL1, VL2.

FIG. 9 is a cross-sectional view of the central portion CP in which the plurality of first reflecting structures 60 are enlarged. Here, six first reflective structures 60-1 to 60-6 are shown arranged in order from the first portion P1 (left side in the figure) to the second portion P2 (right side in the figure), but the central portion is shown. The number of the first reflective structures 60 arranged in the CP is not limited to this. For example, each first reflecting structure 60 has the illustrated cross-sectional shape and extends in the second direction Y.

The first reflective structure 60 has a first reflective surface 61 and a second reflective surface 62. The first reflecting surface 61 is a plane facing the first end portion 53 on the left side of the cross section of FIG. 9, and reflects the light from the first light source LS1 toward the second surface 52. The second reflecting surface 62 is a flat surface facing the second end portion 54 on the right side of the cross section of FIG. 9, and reflects the light from the second light source LS2 toward the second surface 52.

Here, "the first reflecting surface 61 faces the first end portion 53" means that the distance between the end portion of the first reflecting surface 61 on the second end portion 54 side and the second surface 52 is the first end. This means that the first reflecting surface 61 is inclined with respect to the XY plane so as to be smaller than the distance between the end of the first reflecting surface 61 on the portion 53 side and the second surface 52. The same applies to the fourth reflecting surface 81 described later. Further, "the second reflecting surface 62 faces the second end portion 54" means that the distance between the end portion of the second reflecting surface 62 on the first end portion 53 side and the second surface 52 is the second end portion. This means that the second reflecting surface 62 is inclined with respect to the XY plane so as to be smaller than the distance between the end of the second reflecting surface 62 on the 54 side and the second surface 52. The same applies to the third reflecting surface 71 described later.

In the example of FIG. 9, the first reflective structure 60 is arranged between the first reflective surface 61 and the adjacent first reflective surface 61, or between the second reflective surface 62 and the adjacent second reflective surface 62. Has a flat surface 63 that is formed. The flat surface 63 is, for example, parallel to the second surface 52, and reflects the light from each of the light sources LS1 and LS2 at a shallow angle that is totally reflected by the second surface 52. As a result, the light from the first light source LS1 propagates well beyond the central portion CP to the second portion P2. Similarly, the light from the second light source LS2 propagates well beyond the central portion CP to the first portion P1.

The first reflecting surface 61 is inclined with respect to the flat surface 63 (or the second surface 52) at an angle θa which is an obtuse angle. The second reflecting surface 62 is inclined with respect to the flat surface 63 (or the second surface 52) at an angle θb which is an obtuse angle. For example, these angles θa and θb are equal to each other. In this case, the angle of the light from the first light source LS1 which is reflected by the first reflecting surface 61, is emitted from the second surface 52, and reaches the prism sheet PS, and the angle of the light from the second reflecting surface 62 is reflected by the second surface 52. The angle of the light emitted from the second light source LS2 that reaches the prism sheet PS is substantially equal. As a result, the light from each of the light sources LS1 and LS2 is supplied to the display panel PNL under the same condition, so that the uneven brightness in the image can be suppressed.

In the example of FIG. 9, in any of the first reflecting structures 60-1 to 60-6, the first reflecting surface 61 is tilted at an angle θa and the second reflecting surface 62 is tilted at an angle θb. Further, the flat surfaces 63 of the first reflective structures 60-1 to 60-6 have the same width in the first direction X.

The width W1 of the first reflecting surface 61 in the first direction X and the width W2 of the second reflecting surface 62 in the first direction X are different in each of the reflecting structures 60-1 to 60-6. That is, the first reflection surface 61 closer to the first portion P1 has a smaller width W1, and the first reflection surface 61 closer to the second portion P2 has a larger width W1. On the contrary, the second reflection surface 62 closer to the second portion P2 has a smaller width W2, and the second reflection surface 62 closer to the first portion P1 has a larger width W2.

From another point of view, the areas of the plurality of first reflecting surfaces 61 increase as approaching from the first portion P1 to the second portion P2. On the contrary, the areas of the plurality of second reflecting surfaces 62 increase as the area approaches the first portion P1 from the second portion P2.

Further, in the present embodiment, since the flat surfaces 63 of the first reflecting structures 60-1 to 60-6 are constant, the density of the plurality of first reflecting surfaces 61 in the first surface 51 varies from the first portion P1. It increases as it approaches the second portion P2. On the contrary, the densities of the plurality of second reflecting surfaces 62 on the first surface 51 increase from the second portion P2 toward the first portion P1.

From another viewpoint, when the first reflecting structure 60 is closer to the first end 53 side than the center C, the area of the first reflecting surface 61 in the first reflecting structure 60 is the area of the second reflecting surface 62. Smaller than. When the first reflecting structure 60 is located closer to the second end 54 side than the center C, the area of the second reflecting surface 62 in the first reflecting structure 60 is smaller than the area of the first reflecting surface 61.

FIG. 10 is a cross-sectional view of the first portion P1 in which the plurality of second reflective structures 70 are enlarged. Here, two second reflective structures 70-1 and 70-2 arranged in the first direction X are shown. For example, each second reflective structure 70 has the illustrated cross-sectional shape and extends in the second direction Y.

The second reflective structure 70 has a third reflective surface 71 and a flat surface 72. The third reflection surface 71 is a flat surface facing the second end portion 54 on the right side of the cross section of FIG. 10, and reflects the light from the second light source LS2 toward the second surface 52. The flat surface 72 is, for example, parallel to the second surface 52, and reflects the light from each of the light sources LS1 and LS2 at a shallow angle that is totally reflected by the second surface 52. In the example of FIG. 10, the second reflective structure 70 does not have a reflective surface that faces the first end portion 53.

The third reflecting surface 71 is inclined with respect to the flat surface 72 (or the second surface 52) at an angle θc which is an obtuse angle. The width W3 of the third reflecting surface 71 in the first direction X may be different in each reflecting structure 70. The thinner the light guide plate LG is, the more times the light from the second light source LS2 is reflected by the first surface 51 and the second surface 52. Therefore, if the areas of the respective third reflecting surfaces 71 are the same, the closer the third reflecting surface 71 is to the first end portion 53, the more the light from the second light source LS2 is reflected, and the second surface 52 has uneven brightness. obtain. Therefore, the width W3 may be reduced as the third reflecting surface 71 is closer to the first end portion 53.

FIG. 11 is a cross-sectional view of the second portion P2 in which the plurality of third reflective structures 80 are enlarged. Here, two third reflective structures 80-1 and 80-2 arranged in the first direction X are shown. For example, each third reflection structure 80 has the illustrated cross-sectional shape at any position in the second direction Y.

The third reflective structure 80 has a fourth reflective surface 81 and a flat surface 82. The fourth reflecting surface 81 is a plane facing the first end portion 53 on the left side of the cross section of FIG. 11, and reflects the light from the first light source LS1 toward the second surface 52. The flat surface 82 is, for example, parallel to the second surface 52, and reflects the light from each of the light sources LS1 and LS2 at a shallow angle that is totally reflected by the second surface 52. In the example of FIG. 11, the third reflective structure 80 does not have a reflective surface facing the second end 54.

The cross-sectional shape of the second portion P2 shown in FIG. 11 corresponds to the cross-sectional shape of the first portion P1 shown in FIG. Therefore, the description of the conditions applicable to the angle θd formed by the fourth reflecting surface 81 and the flat surface 82 and the width W4 of the fourth reflecting surface 81 is omitted.

Subsequently, the effect of the present embodiment will be described based on the graph of the luminance change shown in FIG. In the present embodiment, a plurality of first reflecting surfaces 61 are provided in the central portion CP, and the area of these first reflecting surfaces 61 increases as they approach the second portion P2. Therefore, the brightness of the light L1 reflected by the first reflecting surface 61 and emitted from the second surface 52 does not change steeply as shown in FIG. 5, but gradually increases from the left end to the right end of the central portion CP in the drawing. Rise.

Similarly, in the present embodiment, the plurality of second reflecting surfaces 62 are provided in the central portion CP, and the area of these second reflecting surfaces 62 increases as the area approaches the first portion P1. Therefore, the brightness of the light L2 reflected by the second reflecting surface 62 and emitted from the second surface 52 also gradually increases from the right end to the left end in the figure of the central portion CP.

As described above, in the present embodiment, in the central portion CP, the brightness when the light L1 from the first light source LS1 is emitted from the second surface 52 from the first end portion 53 side toward the second end portion 54 side is sequentially. It has a brightness gradient characteristic that becomes higher and the brightness when the light L2 from the second light source LS2 is emitted from the second surface 52 from the second end portion 54 side toward the first end portion 53 side becomes sequentially higher.

Here, it is assumed that the luminance distribution of the light L1 slightly shifts in the direction indicated by the arrow D1, and the luminance distribution of the light L2 slightly shifts in the direction indicated by the arrow D2. In the example of FIG. 5, such a shift causes the combined light L to drop sharply at the center C and in the vicinity thereof. However, in the example of FIG. 8, since the brightness of the lights L1 and L2 changes gently in the central portion CP, the brightness of the combined light L only slightly decreases as shown by the broken line La. Therefore, the generation of dark lines as shown in FIG. 7 is suppressed.

Even when the luminance distributions of the lights L1 and L2 deviate in the opposite directions, the luminance of the combined light L only slightly increases as shown by the broken line Lb. Therefore, the generation of bright lines in the center C and its vicinity is also suppressed.

Further, since the light emitted by the first light source LS1 is the laser light, a region NA where the light does not pass is generated in the first portion P1 as shown in FIG. If the light from the first light source LS1 is emitted in the first portion P1, luminance unevenness corresponding to the area NA occurs. On the other hand, in the present embodiment, in the first portion P1, the first surface 51 does not have a reflecting surface that faces the first end portion 53. Therefore, in the first portion P1, the light from the first light source LS1 does not radiate much from the second surface 52, so that the uneven brightness is suppressed.

Similarly, in the present embodiment, the first surface 51 does not have a reflecting surface that faces the second end portion 54 in the second portion P2. Therefore, uneven brightness in the second portion P2 due to the light from the second light source LS2 is suppressed.

Further, by using the illumination device 3 that can realize such a favorable luminance distribution, the display quality of the display device 1 can be improved. In addition to the above, various suitable effects can be obtained from this embodiment.

[Second Embodiment]
The shape of the first reflective structure 60 is not limited to that shown in FIG. 9. FIG. 12 is a sectional view of the central portion CP in the second embodiment. In the example of FIG. 9, the first reflecting structure 60 has a shape protruding downward so that the flat surface 63 is the top surface. On the other hand, the first reflecting structure 60 in the example of FIG. 12 has a shape recessed upward (in the direction toward the second surface 52) so that the flat surface 63 serves as the bottom surface.

Even in this case, the same effect as that of the first embodiment can be obtained. In addition, the shape of the first surface 51 in the central portion CP can be modified in various ways.

[Third Embodiment]
The lighting device 3 may include a reflecting member that returns the light leaking from the first surface 51 to the light guide plate LG. FIG. 13: is sectional drawing which shows an example of the illuminating device 3 provided with the reflection member. The lighting device 3 includes a flat plate-shaped reflecting member 90 facing the first surface 51. As the reflecting member 90, for example, a sheet material made of a metal material can be used.

FIG. 14: is sectional drawing which shows the other example of the illuminating device 3 provided with the reflection member 90. As shown in FIG. In the example of this figure, the reflecting member 90 has a first region 91 and a second region 92. The first region 91 is parallel to the first surface 51 of the first portion P1. The second region 92 is parallel to the first surface 51 of the second portion P2. The first region 91 faces the left half of the first portion P1 and the central portion CP. The second area 92 faces the right half of the second portion P2 and the central portion CP.

FIG. 15 is a cross-sectional view showing still another example of the lighting device 3 including the reflection member 90. In the example of this figure, the reflection member 90 has a first region 91, a second region 92, and a third region 93. The third region 93 is parallel to the first surface 51 in the central portion CP. The first region 91, the second region 92, and the third region 93 face the first portion P1, the second portion P2, and the central portion CP, respectively. When the first surface 51 in the central portion CP is not flat as shown in FIG. 9, the third region 93 may be a curved surface along the first surface 51.

If the reflecting member as described above is provided, the light leaking from the first surface 51 can be effectively used and the brightness of the second surface 52 can be increased. As a result, power saving of the lighting device 3 and improvement of the image quality of the display device 1 can be expected.

[Fourth Embodiment]
FIG. 16 is a schematic cross-sectional view of the lighting device 3 according to the fourth embodiment. The lighting device 3 includes a light guide plate LG, a first light source LS1, and a reflecting member 90. In the present embodiment, the first end portion 53 includes an incident surface 53a and a side surface 53b. The configurations of the above-described embodiments can be applied to the light guide plate LG and the reflection member 90.

The incident surface 53a is inclined with respect to the second surface 52 at an angle θin. The angle θin is an acute angle larger than the first angle θ1 described above (θ1<θin<90°). The side surface 53b is, for example, a plane parallel to the YZ plane. Although the incident surface 53a is a flat surface in the example of FIG. 16, the incident surface 53a may be a curved surface. Further, the first end portion 53 does not have to have the side surface 53b.

The first irradiation direction DL1, which is the direction in which the first light source LS1 emits light, is inclined with respect to the first main surface 51. That is, in this embodiment, the first irradiation direction DL1 does not coincide with the first direction X in a cross-sectional view. However, in the plan view, the first irradiation direction DL1 and the first direction X coincide with each other.

The first light source LS1 overlaps the light guide plate LG in the thickness direction (third direction Z) of the light guide plate LG. In the example of FIG. 16, all the first light sources LS1 overlap the light guide plate LG, but a part of the first light source LS1 may overlap the light guide plate LG.

Even with the above configuration, the same effect as that of each of the above-described embodiments can be obtained. Further, by disposing the first light source LS1 in the space below the light guide plate LG, it is possible to reduce the size of the illumination device 3 or the display device 1 and the size of the frame region.
The same configurations as the first end portion 53 and the first light source LS1 disclosed in the present embodiment can be applied to the second end portion 54 and the second light source LS2.

[Fifth Embodiment]
FIG. 17 is a schematic sectional view of the lighting device 3 according to the fifth embodiment. The lighting device 3 includes a light guide plate LG, a first light source LS1, and a reflecting member 90. The configurations of the above-described embodiments can be applied to the light guide plate LG and the reflection member 90.

The first light source LS1 overlaps the light guide plate LG in the thickness direction (third direction Z) of the light guide plate LG. In the example of FIG. 17, all the first light sources LS1 overlap the light guide plate LG, but a part of the first light source LS1 may overlap the light guide plate LG.

Further, the lighting device 3 includes the bent body 100 arranged near the first end portion 53. The bent body 100 shown in FIG. 17 is a prism having a triangular shape in the XZ cross section and extending in the second direction Y. Specifically, the bent body 100 has a first surface 101, a second surface 102, and a third surface 103. As an example, one bent body 100 may be provided for each of the plurality of first light sources LS1 arranged in the second direction Y as shown in FIG. Further, one bent body 100 may be provided for each of the two or more first light sources LS1, or one bent body 100 may be provided for all the first light sources LS1.

The first surface 101 has an entrance area 101a and an exit area 101b. The incident area 101a faces the first light source LS1. The emission area 101b faces the first end portion 53 of the light guide plate LG. In the example of FIG. 17, the first surface 101 is parallel to the third direction Z, but the first surface 101 may be tilted with respect to the third direction Z. The second surface 102 and the third surface 103 are inclined at a predetermined angle with respect to the first surface 101.

The light emitted from the first light source LS1 enters the bent body 100 from the incident area 101a. The incident light is reflected by the second surface 102, further reflected by the third surface 103, and emitted from the emission area 101b. The emitted light is applied to the first end portion 53 of the light guide plate LG along the first irradiation direction DL1 and propagates through the light guide plate LG while being reflected by the surfaces 51 and 52 of the light guide plate LG. As described above, in the present embodiment, the optical path of the light emitted from the first light source LS1 is bent in the first irradiation direction DL1 by the bending body 100 and is incident on the light guide plate LG.

Even with the above configuration, the same effect as that of each of the above-described embodiments can be obtained. Further, by using the bent body 100 as in the present embodiment, the degree of freedom of the arrangement position of the first light source LS1 is increased. Therefore, by arranging the first light source LS1 in the space below the light guide plate LG as shown in FIG. 17, for example, the illumination device 3 or the display device 1 can be downsized and the frame region can be narrowed.

Although the bent body 100 is a prism in FIG. 17, the bent body 100 may be a reflecting member (mirror member) having a shape corresponding to the second surface 102 and the third surface 103.

The bent body 100 may have a structure in which the light from the first light source LS1 is reflected only once to irradiate the first end portion 53, or may be reflected three times or more to irradiate the first end portion 53. It may have a structure.

The configuration described in the vicinity of the first light source LS1 in the present embodiment can be similarly applied to the second light source LS2 side.

As described above, based on the lighting device and the display device described as the embodiments of the present invention, all the lighting devices and the display devices that can be appropriately modified and implemented by those skilled in the art, as long as they include the gist of the present invention, It belongs to the scope of the invention.

Various modifications are conceivable to those skilled in the art within the scope of the idea of the present invention, and it is understood that these modifications also belong to the scope of the present invention. For example, those skilled in the art appropriately add, delete, or change the design of each of the above-described embodiments, or add or omit steps or change the conditions of the present invention. As long as it has the gist, it is included in the scope of the present invention.

Further, regarding other operational effects brought about by the modes described in the respective embodiments, those apparent from the description of the present specification or those which can be appropriately conceived by a person skilled in the art are understood to be naturally brought about by the present invention. To be done.

DESCRIPTION OF SYMBOLS 1... Display device, 2... Display panel, 3... Illumination device, SUB1... 1st substrate, SUB2... 2nd substrate, LC... Liquid crystal layer, DA... Display area, LG... Light guide plate, PS... Prism sheet, DS... Diffusion Sheet, 51... First surface, 52... Second surface, 53... First end portion, 54... Second end portion, CP... Central portion, P1... First portion, P2... Second portion, 60... First reflection Structure, 70... 2nd reflective structure, 80... 3rd reflective structure, LS1... 1st light source, LS2... 2nd light source, 90... Reflecting member.

Claims (9)

A first light source and a second light source that emit laser light;
Reflects light incident from the first end irradiated with light from the first light source, the second end irradiated with light from the second light source, the first end and the second end. A light guide plate having a first surface and a second surface from which the light reflected by the first surface is emitted;
The light guide plate is
A central portion located between the first end and the second end;
A first portion located between the first end portion and the central portion, the light from the second light source being emitted from the second surface with higher brightness than the light from the first light source;
A second portion that is located between the second end portion and the central portion and that emits light from the first light source from the second surface with higher brightness than light from the second light source. ,
In the central portion, the brightness when the light from the first light source is emitted from the second surface gradually increases from the first end side toward the second end side, and the second end From the side toward the first end portion side, has a brightness gradient characteristic in which the brightness when the light from the second light source is emitted from the second surface is sequentially increased.
Lighting equipment. In the central portion, the first surface reflects the light from the first light source and emits the light from the second surface, and reflects the light from the second light source. Including a plurality of second reflecting surfaces to be emitted from the second surface,
The areas or densities of the plurality of first reflecting surfaces increase from the first portion toward the second portion,
Areas or densities of the plurality of second reflecting surfaces increase from the second portion toward the first portion,
The lighting device according to claim 1. The angle at which the first reflective surface is inclined with respect to the second surface and the angle at which the second reflective surface is inclined with respect to the second surface are the same.
The lighting device according to claim 2. The first surface includes a flat surface parallel to the second surface between the adjacent first reflective surfaces or between the adjacent second reflective surfaces,
The lighting device according to claim 2 or 3. The second surface is a flat surface,
The light guide plate has a shape in which the thickness increases from the first end portion toward the central portion and the thickness increases from the second end portion toward the central portion.
The lighting device according to any one of claims 1 to 4. In the first portion, the first surface has a third reflecting surface facing the second end, and does not have a reflecting surface facing the first end.
The lighting device according to any one of claims 1 to 5. In the second portion, the first surface has a fourth reflecting surface facing the first end, and does not have a reflecting surface facing the second end.
The lighting device according to any one of claims 1 to 6. An illumination device according to any one of claims 1 to 7,
A display panel facing the second surface and displaying an image using light emitted from the second surface;
Display device. Further comprising a prism sheet disposed between the light guide plate and the display panel,
The prism sheet has a plurality of prisms protruding toward the light guide plate,
The display device according to claim 8.

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