Lighting devices and display devices

Abstract

To provide a lighting device with improved light extraction efficiency. [Solution] In the lighting device, the cross-sectional shape of the light guide plate is a trapezoidal shape in which the upper side is shorter than the lower side, and the light guide plate comprises a first surface facing the reflector and a second surface facing the optical sheet, the first surface is provided with a plurality of first protrusions, and the second surface is provided with a plurality of second protrusions, each of the plurality of first protrusions has a first base angle, a second base angle and a first vertex angle and has a triangular cross-sectional shape that protrudes downward, and each of the plurality of second protrusions has a third base angle, a fourth base angle and a second vertex angle and has a triangular cross-sectional shape that protrudes upward, the third base angle is larger than the first base angle.

Description

Technical Field

[0001] Embodiments of the present invention relate to a lighting device and a display device.

Background Art

[0002] A lighting device for illuminating a display panel has been developed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] This embodiment provides a lighting device with improved light extraction efficiency. By providing such a lighting device, it is possible to obtain a display device with high luminance.

Means for Solving the Problems

[0005] A lighting device according to an embodiment includes [[ID=X]] a light guide plate having a first side and a second side, a plurality of light source elements provided facing the first side, a first reflector provided below the light guide plate, an optical sheet provided on the light guide plate, [[ID=5X]] a second reflector provided in contact with the second side, and the cross-sectional shape of the light guide plate is a trapezoidal shape with the upper side shorter than the lower side, the light guide plate includes a first surface facing the first reflector and a second surface facing the optical sheet, a plurality of first convex portions are provided on the first surface, a plurality of second convex portions are provided on the second surface, Each of the aforementioned plurality of first protrusions has a first base angle, a second base angle, and a first vertex angle, and has a triangular cross-sectional shape that protrudes downward. Each of the aforementioned multiple second protrusions has a third base angle, a fourth base angle, and a second vertex angle, and has a triangular cross-sectional shape that protrudes upward. The third base angle is greater than the first base angle.

[0006] Furthermore, the lighting device according to one embodiment is A light guide plate having a first side and a second side, A plurality of light source elements are provided opposite the first side, A first reflector is provided below the light guide plate, An optical sheet provided on the light guide plate, A second reflector is provided adjacent to the aforementioned second side, Equipped with, The cross-sectional shape of the light guide plate is a trapezoidal shape in which the upper side is shorter than the lower side. The light guide plate comprises a first surface facing the first reflector and a second surface facing the optical sheet. The first surface is provided with a plurality of first protrusions, The second surface is provided with a plurality of second protrusions, Each of the aforementioned plurality of first protrusions has a first base angle, a second base angle, and a first vertex angle, and has a triangular cross-sectional shape that protrudes downward. Each of the aforementioned multiple second protrusions has a third base angle, a fourth base angle, and a second vertex angle, and has a triangular cross-sectional shape that protrudes upward. The third base angle and the first base angle are equal. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a perspective view showing a schematic configuration of the display device according to this embodiment. [Figure 2] Figure 2 is a plan view showing the schematic configuration of the display device. [Figure 3] Figure 3 is a cross-sectional view showing the cross-sectional structure of the display device along the line A1-A2 in Figure 2. [Figure 4]FIG. 4 is a cross-sectional view showing a schematic structure of a lighting device of a comparative example. [Figure 5] FIG. 5 is a cross-sectional view showing a convex portion provided on a light guide plate. [Figure 6] FIG. 6 is a cross-sectional view showing a schematic structure of a lighting device according to an embodiment. [Figure 7] FIG. 7 is a cross-sectional view showing a convex portion provided on a light guide plate. [Figure 8] FIG. 8 is a cross-sectional view showing another configuration example of the lighting device according to the embodiment. [Figure 9] FIG. 9 is a cross-sectional view showing a convex portion provided on a light guide plate. [Figure 10] FIG. 10 is a plan view for explaining an application example of the lighting device. [Figure 11] FIG. 11 is a cross-sectional view showing a cross-sectional structure of a display device along line B1-B2 in FIG. 10. [Figure 12] FIG. 12 is a perspective view showing an example of an appearance of a display device according to Configuration Example 3.

Embodiments for Carrying Out the Invention

[0008] Hereinafter, each embodiment of the present invention will be described with reference to the drawings. Note that the disclosure is merely an example, and for those that can be easily conceived by those skilled in the art with appropriate modifications while maintaining the gist of the invention, they are naturally included in the scope of the present invention. Also, for the purpose of making the description clearer, the drawings may schematically represent the width, thickness, shape, etc. of each part compared to the actual aspect, but this is merely an example and does not limit the interpretation of the present invention. Further, in this specification and each figure, elements similar to those described above with respect to the previously shown figures may be denoted by the same reference numerals, and detailed descriptions may be omitted as appropriate.

[0009] The embodiments described in this specification are not general ones, but embodiments that explain the same or corresponding special technical features of the present invention. Hereinafter, with reference to the drawings, a lighting device according to an embodiment will be described in detail.

[0010] In this embodiment, the first direction X, the second direction Y, and the third direction Z are orthogonal to each other, but they may intersect at angles other than 90 degrees. The direction toward the tip of the arrow in the third direction Z is defined as up or upward, and the direction opposite to the direction toward the tip of the arrow in the third direction Z is defined as down or downward. The first direction X, the second direction Y, and the third direction Z may also be referred to as the X direction, the Y direction, and the Z direction, respectively.

[0011] Furthermore, when referring to "the second member above the first member" and "the second member below the first member," the second member may be in contact with the first member or may be located away from the first member. In the latter case, a third member may be interposed between the first member and the second member. On the other hand, when referring to "the second member above the first member" and "the second member below the first member," the second member is in contact with the first member.

[0012] Furthermore, assuming that there is an observation position for observing the lighting device on the tip side of the arrow in the third direction Z, viewing from this observation position toward the XY plane defined by the first direction X and the second direction Y is called a plan view. Viewing the cross-section of the lighting device in the XZ plane defined by the first direction X and the third direction Z, or in the YZ plane defined by the second direction Y and the third direction Z, is called a cross-sectional view.

[0013] [Embodiment 1] Figure 1 is a perspective view showing a schematic configuration of a display device according to an embodiment. The display device DSP includes a display panel PNL, an illumination device ILD, a drive IC chip ICP for driving the display panel PNL, a flexible circuit board FPC1 for supplying control signals to the display panel PNL, and a flexible circuit board FPC2 for supplying control signals to the illumination device ILD. For example, flexible circuit boards FPC1 and FPC2 may be connected to a control module that controls the operation of the display panel PNL and the illumination device ILD.

[0014] The display panel PNL comprises a substrate SUB1 (array substrate) and a substrate SUB2 (opposing substrate) facing substrate SUB1. The display panel PNL has a display area DA for displaying images. The display panel PNL includes, for example, a plurality of pixels PX arranged in a matrix within the display area DA.

[0015] The ILD lighting device comprises a light source element LS1 and a light guide plate LG facing the substrate SUB1. The light source element LS1 faces one side of the light guide plate LG. Although Figure 1 shows one light source element LS1, multiple light source elements LS1 may be provided.

[0016] In the configuration example shown in Figure 1, substrates SUB1, SUB2, and light guide plate LG have a short side along the first direction X and a long side along the second direction Y, and their shape in plan view is rectangular. However, the shape of substrates SUB1, SUB2, and light guide plate LG is not limited to this, and their shape in plan view may be a square, a circle, or other shape.

[0017] Figure 2 is a plan view showing the schematic configuration of the display device. Figure 3 is a cross-sectional view showing the cross-sectional structure of the display device along the line A1-A2 in Figure 2.

[0018] The display device DSP comprises an illumination device ILD and a display panel PNL. The illumination device ILD comprises a reflector REF, a light guide plate LG, a reflector RFB, an optical sheet OPS, and a light source element LS1. The reflector REF, light guide plate LG, and optical sheet OPS are stacked in this order. The display panel PNL is provided on the illumination device ILD.

[0019] In a plan view, the edges extending along the second direction Y of the light guide plate LG are denoted as edges GV1 and GV2. In Figure 2, the edge on the left side of the paper is denoted as edge GV1, and the edge on the right side of the paper is denoted as edge GV2. The light source element LS1 is positioned opposite edge GV1 of the light guide plate LG. The reflector RFB is provided in contact with edge GV2 of the light guide plate LG.

[0020] The light guide plate LG has a rectangular shape in plan view and a trapezoidal shape in cross-section, with the lower side being longer than the upper side. The left side of the trapezoid, side GV1, extends along the third direction Z. The right side of the trapezoid, side GV2, extends at an angle with respect to the third direction Z.

[0021] The light source element LS1 is positioned opposite the edge GV1 of the light guide plate LG. Light emitted from the light source element LS1 is incident on the edge GV1 of the light guide plate LG.

[0022] Note that although edge GV1 is called an edge, it is actually a plane parallel to the YZ plane. Edge GV2 is actually a plane that is inclined at an angle to the YZ plane.

[0023] Multiple protrusions (also called prisms) are provided on the main surfaces of the light guide plate LG and the optical sheet OPS.

[0024] Figure 4 is a cross-sectional view showing the schematic structure of a comparative example lighting device. The lighting device ILDr shown in Figure 4 comprises a reflector REF, a light guide plate LG, a reflector RFB, a prism sheet PRS, and a light source element LS1. The optical sheet OPS shown in Figure 3 corresponds to the prism sheet PRS shown in Figure 4. However, the configuration of the optical sheet OPS is not limited to this, and it may have optical sheets other than prism sheets.

[0025] Of the main surfaces of the light guide plate LG, the surface facing the reflector REF is designated as surface BS. Of the main surfaces of the light guide plate LG, the surface facing the prism sheet PRS is designated as surface US.

[0026] Let the thickness of the light guide plate LG (length along the third direction Z) be d0. The ray width d1 is the same as the thickness d0 (d1=d0).

[0027] Figure 5 is a cross-sectional view showing a protrusion on the light guide plate LG. A protrusion PRM1 is provided on the surface BS of the light guide plate LG, projecting downward (in the opposite direction to the third direction Z). On the other hand, no protrusion is provided on the surface US of the light guide plate LG.

[0028] As described above, the convex portion PRM1 is a convex portion that protrudes downward. Of the base angles of the convex portion PRM1, the angle on the left side of the paper is angle θ11, and the angle on the right side of the paper is angle θ12. The apex angle of the convex portion PRM1 is angle θ13. Angles θ11, θ12, and θ13 may be different. In the example shown in Figure 5, angle θ11 is smaller than angle θ12.

[0029] The light source element LS1 is positioned opposite the edge GV1 of the light guide plate LG. Light LT emitted from the light source element LS1 enters the light guide plate LG from the surface including the edge GV1 and travels in a straight line within the light guide plate LG. When the light LT reaches the edge GV2 of the light guide plate LG, it is reflected downward by the reflector RFB provided on the edge GV2.

[0030] The light reflected by the reflector RFB is defined as optical LTB. Optical LTB propagates between surfaces BS and US of the light guide plate LG in the opposite direction to the first direction X, while satisfying the total internal reflection condition.

[0031] Light LT and light LTB propagate through the inside of the light guide plate LG with a ray width d1. Light LTB, having a ray width d1, is emitted upward by a protrusion (prism) provided on the surface BS. This emitted light is called light RL. Light RL is emitted upward from the surface US of the light guide plate LG and enters the prism sheet PRS. Light RL is then emitted upward by the prism sheet PRS as light DL, which is emitted along the third direction Z, and is emitted above the illumination device ILDr.

[0032] Let angle t1 be the acute angle formed by plane BS and edge GV2. Let angle t2 be the acute angle formed by a virtual line extending plane BS along the first direction X and edge GV2. Let angle t3 be the angle formed by plane BS and light RL.

[0033] However, some light LTB, even after being reflected by surface BS of the light guide plate LG, does not exit upward from surface BS but undergoes total internal reflection at surface US and returns to the light guide plate LG. After total internal reflection at surface US and returning to the interior of the light guide plate LG, the light LTB undergoes total internal reflection again at surface BS. In this way, the light LTB is guided inside the light guide plate LG. If the amount of light LTB that continues to undergo total internal reflection is large, there is a risk that the utilization efficiency of the light LT incident from the light source element LS1 will be reduced.

[0034] The region between the reflection of optical LTB from surface US and the subsequent reflection from surface BS is defined as region NFR. In region NFR, optical LTB with ray width d1 is not reflected, so the light is not lifted upwards.

[0035] Within the surface US, the region from which light DL is emitted is defined as region RLR. Conversely, corresponding to region NFR, a region NLR from which no light is emitted occurs in surface US. In other words, surface US has a bright region RLR from which light DL is emitted, and a dark region NLR from which light DL is not emitted.

[0036] Let LD2 be the distance along the first direction X corresponding to region NFR. Distance LD2 is also the distance corresponding to region NLR. Let LL1 be the distance along the first direction X in region RLR. No light irradiation occurs between the right edge of the light guide plate LG on the plane of the paper and the region where light DL is irradiated, adjacent to edge GV2. Let this region be region NNR. Let LD1 be the distance along the first direction X in region NNR.

[0037] Distances LL1, LD1, and LD2 are expressed by the following formulas. LL1=d0 / ((1 / tant2)+(1 / tant1)) (Equation 1) LD1=d0 / (tant3) (Formula 2) LD2=d0((1 / tant2)-(1 / tant1)) (Equation 3) t2=2(90°−t1) (Equation 4) t3=t2+θ11 (Equation 5)

[0038] For example, let the thickness d0 be 1 [mm] (d0=1). Let angle t1 be 76.75° (t1=76.75°) and angle θ11 be 15° (θ11=15°). From (Equation 4), angle t2 is 26.5° (t2=26.5°). From (Equation 5), angle t3 is 56.5° (t3=56.5°).

[0039] From (Equation 1) and (Equation 4), the distance LL1 is 2.24 [mm] (LL1 = 2.24). From (Equation 3) and (Equation 4), the distance LD2 is 1.77 [mm] (LD2 = 1.77).

[0040] In this embodiment, by providing a protrusion (prism) on the surface US of the light guide plate LG, it is possible to emit the light LTB guided inside the light guide plate LG upwards.

[0041] Figure 6 is a cross-sectional view showing the schematic structure of the lighting device of the embodiment. The lighting device ILD shown in Figure 6 differs from the lighting device ILDr shown in Figure 4 in that multiple protrusions PRM2 are provided on the surface US of the light guide plate LG. Figure 7 is a cross-sectional view showing the protrusions provided on the light guide plate LG.

[0042] As shown in Figure 7, the light guide plate LG is provided with not only the convex portion PRM1 on surface BS but also the convex portion PRM2 on surface US. The convex portion PRM2 is a convex portion that protrudes upward. Of the base angles of the convex portion PRM2, the left side of the paper is denoted as angle θ21, and the right side of the paper is denoted as angle θ22. The apex angle of the convex portion PRM2 is denoted as angle θ23. Angles θ21, θ22, and θ23 may be different. In the example shown in Figure 7, angle θ21 is greater than angle θ22. Also, angle θ21 of the convex portion PRM2 is greater than angle θ11 of the convex portion PRM1. Angles θ23 of the convex portion PRM2 are greater than angle θ13 of the convex portion PRM1.

[0043] As shown in Figure 6, and similarly as in Figure 4, the light LT emitted from the light source element LS1 is incident on the light guide plate LG from the plane containing edge GV1 and propagates within the light guide plate LG. The light LT that reaches edge GV2 of the light guide plate LG is reflected downward by the reflector RFB. The reflected light LTB undergoes repeated total internal reflection between planes BS and US of the light guide plate LG and propagates in the opposite direction to the first direction X.

[0044] Light LTB reflected from surface BS of light guide plate LG is emitted upward by a protrusion (prism) provided on surface BS. The emitted light RL is then emitted from surface US of light guide plate LG and incident on prism sheet PRS. Light RL is then emitted upward by prism sheet PRS as light DL along a third direction Z, and is further emitted above the illumination device ILD.

[0045] As explained in Figure 4, there is optical LTB that is reflected by surface US and returns to the light guide plate LG. After optical LTB undergoes total internal reflection by surface US and returns to the inside of the light guide plate LG, it undergoes total internal reflection again by surface BS. The optical LTB reflected by surface BS propagates toward surface US.

[0046] The light LTB that reaches the surface US is emitted upward by the protrusion PRM2 provided on the surface US. This emitted light is called light RAL. Light RAL is emitted from the surface US of the light guide plate LG and incident on the prism sheet PRS. Light RAL is emitted by the prism sheet PRS as light DAL along the third direction Z and is further emitted upward above the illumination device ILD.

[0047] In the example shown in Figure 6, a region NFR also exists. However, because a protrusion PRM2 is provided on the surface US, the optical LTB is emitted upward. This makes it possible to efficiently extract the optical LTB propagating through the light guide plate LG.

[0048] The region from which optical DAL is emitted is defined as the RAR region. In the ILD illumination device shown in Figure 6, not only the RLR region from which optical DL is emitted, but also the RAR region from which optical DAL is emitted is generated. This increases the amount of light emitted from the ILD illumination device, improving the light extraction efficiency.

[0049] In the example shown in Figure 6, a portion of region RAR overlaps with region RLR. However, the embodiments are not limited to this. Region RAR may not overlap with region RLR and may be positioned separately. Alternatively, the entirety of region RAR may overlap with region RLR. The positional relationship between region RLR and region RAR can be controlled by changing the angles of edge GV2 and reflector RFB with respect to the XY plane, angles θ21, θ22, and θ23 of convex portion PRM2, and refractive index of light guide plate LG.

[0050] Let LL2 be the distance along the first direction X in the region RAR irradiated with optical DAL.

[0051] The distance LL2 is expressed by the following formula. LL2=d0((1 / tant2)-(1 / tant3)) (Equation 6)

[0052] For example, as in Figure 4, let the thickness d0 be 1 [mm] (d0=1). Let angle t1 be 76.75° (t1=76.75°) and angle θ11 be 15° (θ11=15°). Let angle θ21 be 78.5° (θ21=78.5°). From (Equation 4), angle t2 is 26.5° (t2=26.5°). From (Equation 5), angle t3 is 56.5° (t3=56.5°).

[0053] From equations 4, 5, and 6, the distance LL2 is 1.34 mm (LL2 = 1.34).

[0054] According to this embodiment, a lighting device with improved light extraction efficiency can be obtained. By equipping such a lighting device, it is possible to obtain a display device with high brightness.

[0055] <Configuration Example 1> Figure 8 is a cross-sectional view showing another configuration example of the lighting device in the embodiment. The configuration example shown in Figure 8 differs from the configuration example shown in Figure 6 in that it has a convex portion (prism) that reflects light downwards. Figure 9 is a cross-sectional view showing the convex portion provided on the light guide plate.

[0056] As shown in Figure 9, the light guide plate LG is provided with not only a protrusion PRM1 on surface BS but also a protrusion PRM3 on surface US. The protrusion PRM3 is a protrusion that projects upward. Of the base angles of the protrusion PRM3, the left side of the paper is denoted as angle θ31, and the right side of the paper is denoted as angle θ32. The apex angle of the protrusion PRM3 is denoted as angle θ33. Angles θ31, θ32, and θ33 may be different. In the example shown in Figure 9, angle θ31 is smaller than angle θ32.

[0057] In Configuration Example 1, the convex parts PRM1 and PRM3 are arranged in a symmetrical relationship with respect to the first direction X. The angle θ11 of convex part PRM1 and the angle θ31 of convex part PRM3 are equal. The angle θ12 of convex part PRM1 and the angle θ32 of convex part PRM3 are equal. The angle θ13 of convex part PRM1 and the angle θ33 of convex part PRM3 are equal.

[0058] As shown in Figure 8, and similarly as in Figure 4, the light LT emitted from the light source element LS1 is incident on the light guide plate LG from the plane containing edge GV1 and propagates within the light guide plate LG. The light LT that reaches edge GV2 of the light guide plate LG is reflected downward by the reflector RFB. The reflected light LTB undergoes repeated total internal reflection between planes BS and US of the light guide plate LG and propagates in the opposite direction to the first direction X.

[0059] The light LTB reflected from surface BS of the light guide plate LG reaches surface US. The light LT that reaches surface US is emitted downward by a protrusion PRM3 provided on surface US. This downward emitted light is called light RBL. Light RBL is incident on region NFR.

[0060] As explained in Figure 4, the NFR region is a region where optical LTB with a ray width d1 does not occur. In Figure 8, optical RBL also occurs in the NFR region. Optical RBL is emitted upward by a protrusion PRM1 provided on the NFR region (surface BS). This upward emitted light is called optical RCL.

[0061] Light RCL, like light RL, is emitted upward from the surface US of the light guide plate LG and incident on the prism sheet PRS. Light RCL is then emitted upward from the prism sheet PRS as light DBL along the third direction Z, and further emitted above the illumination device ILD.

[0062] In Configuration Example 1, the protrusion PRM3 on the surface US reflects the light LTB propagating through the light guide plate LG downwards. The light RBL reflected downwards is emitted upwards by the protrusion PRM1 on the surface BS. Furthermore, it is emitted upwards as light DBL from the lighting device ILD. This makes it possible to efficiently extract the light LTB propagating through the light guide plate LG.

[0063] The region from which light DBL is emitted is defined as the RBR region. In the ILD illumination device shown in Figure 8, not only the RLR region from which light DL is emitted, but also the RBR region from which light DBL is emitted is generated. This increases the amount of light emitted from the ILD illumination device, improving the light extraction efficiency.

[0064] In the example shown in Figure 8, a portion of region RBR overlaps with region RLR. However, the embodiments are not limited to this. Region RBR may not overlap with region RLR and may be positioned separately. Alternatively, the entirety of region RBR may overlap with region RLR. The positional relationship between region RLR and region RBR can be controlled by changing the angles of edge GV2 and reflector RFB with respect to the XY plane, angles θ31, θ32, and θ33 of convex portion PRM3, and the refractive index of light guide plate LG.

[0065] Let LL3 be the distance along the first direction X of the region RAR irradiated by the optical DBL.

[0066] The distance LL3 is expressed by the following formula. LL3=d0((1 / tant2)-(1 / tant3)) (Equation 7)

[0067] For example, as in Figure 4, let the thickness d0 be 1 [mm] (d0=1). Let angle t1 be 76.75° (t1=76.75°) and angle θ11 be 15° (θ11=15°). Let angle θ31 be 15° (θ31=15°). From (Equation 4), angle t2 is 26.5° (t2=26.5°). From (Equation 5), angle t3 is 56.5° (t3=56.5°).

[0068] From equations (4), (5), and (7), the distance LL3 is 1.34 [mm] (LL3 = 1.34).

[0069] Configuration Example 1 allows for the creation of a lighting device with improved light extraction efficiency. By incorporating such a lighting device, it is possible to obtain a display device with high brightness.

[0070] <Configuration Example 2> Figure 10 is a plan view illustrating an example of an application of the lighting device. The display device DSP shown in Figure 10 includes a lighting device ILDh for the left eye and a lighting device ILDh for the right eye.

[0071] The left eye illumination device ILDh has a similar configuration to the illumination device ILD shown in Figure 2. In Figure 10, the illumination device ILDh comprises a light guide plate LGh and multiple light source elements LS1h. In a plan view, the edges of the light guide plate LGh extending along the second direction Y are designated as edges GV1h and GV2h. In Figure 10, the edge on the left side of the paper is designated as edge GV1h, and the edge on the right side of the paper is designated as edge GV2h. The light source elements LS1h are positioned opposite edge GV1h of the light guide plate LGh.

[0072] The illumination device ILDm for the right eye is positioned symmetrically to the illumination device ILDh with respect to the second direction Y. As shown in Figure 10, the illumination device ILDm comprises a light guide plate LGm and a plurality of light source elements LS1m. In a plan view, the sides of the light guide plate LGm extending along the second direction Y are denoted as sides GV1m and GV2m. In Figure 10, the side on the right side of the paper is denoted as side GV1m, and the side on the left side of the paper is denoted as side GV2h. The light source elements LS1h are provided at a position opposite side GV1h of the light guide plate LGh.

[0073] As shown in Figure 10, for example, light emitted from the light source element LS1h (corresponding to optical LT) and light emitted upward from the light guide plate LGh (corresponding to optical DL, optical DAL, and optical DBL) are combined. As a result, a bright region RAh and a dark region RKh are created in the light guide plate LGh. The width of the bright region RAh is narrower the closer it is to the light source element LS1h. The width of the bright region RAh increases as it moves away from the light source element LS1h.

[0074] Similarly, the light emitted from the light source element LS1m and the light emitted upward from the light guide plate LGm are combined. As a result, a bright region RAm and a dark region RKm are created on the light guide plate LGm. The width of the bright region RAm is narrower the closer it is to the light source element LS1m. The width of the bright region RAm widens as it moves away from the light source element LS1m.

[0075] Figure 11 is a cross-sectional view showing the cross-sectional structure of the display device along line B1-B2 in Figure 10. The display device DSP comprises an illumination device ILDh, a display panel PNLh, an illumination device ILDm, and a display panel PNLm. The display panel PNLh is mounted on the illumination device ILDh. The display panel PNLm is mounted on the illumination device ILDm.

[0076] The lighting device ILDh and display panel PNLh have the same configuration as the lighting device ILD and display panel PNL shown in Figure 3. The lighting device ILDm and display panel PNLm are positioned symmetrically to the lighting device ILDh and display panel PNLh with respect to the YZ plane.

[0077] The lighting device ILDh comprises a reflector REFh, a light guide plate LGh, a reflector RFBh, an optical sheet OPSh, and a light source element LS1h. The reflector REFh, the light guide plate LGh, and the optical sheet OPSh are stacked in this order.

[0078] The light guide plate LGh has sides GV1h and GV2h. Side GV1h is located on the left side of the paper and faces the light source element LS1h. Side GV2h is located on the right side of the paper and faces side GV2m of the light guide plate LGm.

[0079] The ILDm lighting device comprises a reflector REFm, a light guide plate LGm, a reflector RFBm, an optical sheet OPSm, and a light source element LS1m. The reflector REFm, light guide plate LGm, and optical sheet OPSm are stacked in this order.

[0080] The light guide plate LGm has sides GV1m and GV2m. Side GV1m is located on the right side of the paper and faces the light source element LS1m. Side GV2m is located on the left side of the paper and faces side GV2h of the light guide plate LGh.

[0081] The cross-sectional shapes of the light guide plates LGh and LGm are trapezoidal, with the upper side being shorter than the lower side. The reflectors RFBh and RFBm face each other.

[0082] The lighting devices ILDh and ILDm may use the same lighting device ILD as described above. That is, the light guide plates LGh and LGm are provided with a protrusion PRM2 or a protrusion PRM3. More specifically, the lighting device ILDh, which includes the light guide plate LGh, may use the same configuration as the lighting device ILD described above. On the other hand, the lighting device ILDm, which includes the light guide plate LGm, may have a configuration that is symmetrical with respect to the YZ plane with respect to the lighting device ILD described above.

[0083] Figure 12 is a perspective view showing an example of the appearance of a display device according to Configuration Example 3. In Configuration Example 3, the display device DSP includes a head-mounted display (HMD) that is worn on the user's head. Such a display device DSP is used to provide, for example, virtual reality (VR) to the user USR wearing the display device DSP on their head.

[0084] Display panels PNLh and PNLm are positioned so as to be in front of the left and right eyes of the user USR when the user USR is wearing the display device DSP on their head.

[0085] As described above, by equipping the device with a lighting system that has high light extraction efficiency, it is possible to obtain a display device with high brightness.

[0086] In this disclosure, sides GV1 and GV2 of the light guide plate LG are also referred to as the first side and the second side, respectively. Surface BS of the light guide plate LG is referred to as the first surface, and surface US is referred to as the second surface. Reflectors REF and RFB are also referred to as the first reflector and the second reflector, respectively.

[0087] The convex portion PRM1 is referred to as the first convex portion, and the convex portion PRM2 or convex portion PRM2 is referred to as the second convex portion. The cross-sectional shape of the convex portion PRM1 is triangular. The angles θ11, θ12, and θ13 of the convex portion PRM1 are defined as the first base angle, the second base angle, and the first vertex angle, respectively.

[0088] The cross-sectional shapes of protrusions PRM2 and PRM3 are triangular. In other words, the cross-sectional shape of either protrusion PRM2 or PRM3 can also be described as polygonal.

[0089] The angles θ21, θ22, and θ23 of the convex PRM2 are called the third base angle, the fourth base angle, and the second vertex angle, respectively. The angles θ31, θ32, and θ33 of the convex PRM3 are called the third base angle, the fourth base angle, and the second vertex angle, respectively.

[0090] However, the ordinal numbers assigned to the sides and angles are not limited to those mentioned above. Different ordinal numbers may be assigned as needed.

[0091] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of symbols]

[0092] DAL...light, DBL...light, DSP...display device, GV1...side, GV2...side, ILD...lighting device, LG...light guide plate, LS1...light source element, LT...light, LTB...light, PNL...display panel, PRM1...protrusion, PRM2...protrusion, PRM3...protrusion, RAL...light, RBL...light, RCL...light, RFB...reflector, d1...ray width.

Claims

1. A light guide plate having a first side and a second side, A plurality of light source elements are provided opposite the first side, A first reflector is provided below the light guide plate, An optical sheet provided on the light guide plate, A second reflector is provided adjacent to the second side, Equipped with, The cross-sectional shape of the light guide plate is a trapezoidal shape in which the upper side is shorter than the lower side. The light guide plate comprises a first surface facing the first reflector and a second surface facing the optical sheet. The first surface is provided with a plurality of first protrusions, The second surface is provided with a plurality of second protrusions, Each of the plurality of first protrusions has a first base angle, a second base angle, and a first vertex angle, and has a triangular cross-sectional shape that protrudes downward. Each of the aforementioned multiple second protrusions has a third base angle, a fourth base angle, and a second vertex angle, and has a triangular cross-sectional shape that protrudes upward. A lighting device in which the third base angle is larger than the first base angle.

2. The lighting device according to claim 1, wherein the second vertex angle is greater than the first vertex angle.

3. The lighting device according to claim 1, A display panel is provided on the aforementioned lighting device, A display device equipped with the following features.

4. A light guide plate having a first side and a second side, A plurality of light source elements are provided opposite the first side, A first reflector is provided below the light guide plate, An optical sheet provided on the light guide plate, A second reflector is provided adjacent to the second side, Equipped with, The cross-sectional shape of the light guide plate is a trapezoidal shape in which the upper side is shorter than the lower side. The light guide plate comprises a first surface facing the first reflector and a second surface facing the optical sheet. The first surface is provided with a plurality of first protrusions, The second surface is provided with a plurality of second protrusions, Each of the plurality of first protrusions has a first base angle, a second base angle, and a first vertex angle, and has a triangular cross-sectional shape that protrudes downward. Each of the aforementioned multiple second protrusions has a third base angle, a fourth base angle, and a second vertex angle, and has a triangular cross-sectional shape that protrudes upward. A lighting device in which the third base angle and the first base angle are equal.

5. The fourth base angle and the second base angle are equal, The lighting device according to claim 4, wherein the second vertex angle and the first vertex angle are equal.

6. The lighting device according to claim 4, A display panel is provided on the aforementioned lighting device, A display device equipped with the following features.

Images