Light guide plate, lighting device, display device

Abstract

This invention provides a light guide plate that reduces brightness unevenness. A light guide plate includes: a base having a surface and a light incident surface arranged intersecting the surface at one end; and a plurality of convex lenses disposed on a side of the base opposite to the surface, extending along a first direction and arranged along a second direction substantially orthogonal to the first direction. The base includes at least a first region relatively close to the light incident surface and a second region relatively far from the light incident surface. A plurality of first bottoms are disposed in the first region, each first bottom being a surface disposed between adjacent convex lenses in the second direction and arranged obliquely relative to the first direction.

Description

Technical Field

[0001] This disclosure relates to light guide plates, lighting devices, and display devices. Background Technology

[0002] Japanese Patent Application Publication No. 2013-206577 discloses a light guide plate having a first optical element with a light-rising pattern on a first main surface and a second optical element with a light-sealing lens on a second main surface. Bubbles of appropriate size and quantity are contained on the inner side of the second optical element or up to a position equidistant from the inner side of the second optical element and the lower layer of the second optical element at the same height as the second optical element. However, it is considered difficult to appropriately control the size and dispersion of the bubbles during the manufacture of the light guide plate.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2013-206577 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] One of the objectives of this invention is to provide a light guide plate or the like that reduces brightness unevenness.

[0008] means for solving problems

[0009] One aspect of the light guide plate disclosed herein includes: (a) a base having a surface and a light incident surface disposed at one end of the surface intersecting the surface; and (b) a plurality of convex lenses disposed on a side of the base opposite to the surface, extending in a first direction and arranged along a second direction substantially orthogonal to the first direction; (c) the base including at least a first region relatively close to the light incident surface and a second region relatively far from the light incident surface; and (d) a plurality of first bottoms disposed in the first region, the plurality of first bottoms being surfaces respectively disposed between adjacent convex lenses in the second direction and being surfaces disposed obliquely relative to the first direction.

[0010] One type of lighting device disclosed herein includes: the light guide plate described above [1]; a reflector disposed on one side of the light guide plate; a light condenser disposed on the light emitting side of the light guide plate; and a plurality of light sources disposed opposite to the light incident surface of the light guide plate.

[0011] One type of display device disclosed herein includes: the lighting device described above [2]; and a liquid crystal panel disposed on the light emitting side of the lighting device.

[0012] According to embodiments of this disclosure, light guide plates, lighting devices, and display devices with reduced brightness non-uniformity can be obtained. Attached Figure Description

[0013] Figure 1 This is a perspective view of the light guide plate according to the first embodiment.

[0014] Figure 2 This is a top view of the light guide plate of the first embodiment, viewed from above.

[0015] Figure 3 (A) is Figure 2 A partial cross-sectional view at line AA is shown. Figure 3 (B) is Figure 2 The partial cross-section at line BB shown. Figure 3 (C) is a diagram used to illustrate the ratio of each convex lens to the bottom.

[0016] Figure 4 (A) is Figure 2 The cross-sectional view at the CC line shown. Figure 4 (B) is a top view of the bottom shape of the first and second regions.

[0017] Figure 5 Figure (A) is a diagram showing an example of the light emission distribution of the light guide plate according to the first embodiment. Figure 5 (B) is the light distribution diagram of the light guide plate of the comparative example.

[0018] Figure 6 (A) is a schematic side view showing an example of the configuration of a lighting device and a display device equipped with the lighting device according to one embodiment. Figure 6 (B) is a schematic top view used to illustrate the structure of the liquid crystal panel.

[0019] Figure 7 (A) is a cross-sectional view of the light guide plate according to the second embodiment. Figure 7 (B) is a diagram showing the top view of the shape from the bottom of the first region to the second region.

[0020] Figure 8 (A) is a cross-sectional view of the light guide plate according to the third embodiment. Figure 8 (B) is a diagram showing the top view of the shape from the bottom of the first region to the second region.

[0021] Figure 9 (A) is a cross-sectional view of the light guide plate according to the fourth embodiment. Figure 9 (B) Figure 9 (C) is a diagram illustrating an example of a method for specifying the tilt angle of each surface.

[0022] Figure 10 (A) is a cross-sectional view of the light guide plate according to the fifth embodiment. Figure 10 (B) is a diagram showing the top view of the shape from the bottom of the first region to the second region. Detailed Implementation

[0023] Figure 1 This is a perspective view of the light guide plate according to the first embodiment. The light guide plate (light guide sheet) 1 shown in the figure is configured to include a base 10 and a plurality of convex lenses 11. The light guide plate 1 of this embodiment guides light incident from the light incident surface 13 of the base 10 and emits light in a planar shape upward in the figure through the upper surface (emission surface) of each convex lens 11. The light guide plate 1 is made of a light-transmitting material and is a transparent flat plate (or film). The material constituting the light guide plate 1 is not particularly limited as long as it is light-transmitting; for example, various resin materials (acrylic resin as an example) with a refractive index of about 1.5 to 1.75 are preferred.

[0024] The base 10 has: a lower surface (one side) having a flat portion; a light incident surface 13 disposed approximately orthogonally to the lower surface; and a tapered portion 12. The base 10 has a flat plate shape that extends in the XY direction and has thickness in the Z direction. In this embodiment, the Y-direction length of the base 10 is relatively longer than the X-direction length, but it is not limited to this, and the top view shape is not limited to a rectangular shape. It should be noted that "approximately orthogonal" in this specification does not necessarily mean intersecting at a strict 90° angle, and manufacturing errors are allowed, for example, intersecting within a range of 90° ± 10°. In addition, the aforementioned one side may also have a light extraction structure that reflects light emitted from the light source and incident on the light incident surface 13 toward that side to the emission surface side. For example, fine shapes (light extraction structures) as described in Japanese Patent No. 5313098 and Japanese Patent No. 6184205 can be applied.

[0025] Each of the plurality of convex lenses 11 has a semi-cylindrical shape extending along the Y direction in the figure and is arranged along the X direction, which is approximately orthogonal to the Y direction. The light guide plate 1 of this embodiment has eight convex lenses 11, but the number of convex lenses 11 is not limited. In the figure, only a few convex lenses 11 are labeled (described later). Figure 2(The same applies to the middle section). Each convex lens 11 is disposed on the side (upper surface) opposite to the lower surface of the base 10, configured with its top facing upwards (Z direction) as shown in the figure, and its respective edge line along the Y direction. In this embodiment, each convex lens 11 is arranged such that the height of the top (highest position in the Z direction) of each convex lens 11 is approximately the same based on the lower surface of the base 10. In addition, the height of the vertex of each convex lens 11 based on the lower surface of the base 10 is approximately constant along the Y direction. Furthermore, the length (lens width) of each convex lens 11 along the X direction is approximately the same. A lens composed of such a plurality of convex lenses 11 is also called a cylindrical lens.

[0026] A tapered portion 12 is disposed at one end of the base 10 in the Y direction and close to the light incident surface 13. This tapered portion 12 has a wedge-shaped shape with its upper surface inclined, increasing in thickness (height in the Z direction) as it approaches the light incident surface 13. The lower surface of the tapered portion 12 is common to the lower surface of the base 10. The height of the tapered portion 12, based on the lower surface of the base 10, is approximately the same as the height of each convex lens 11 at the position of the light incident surface 13. Each convex lens 11 appears to be recessed into the interior of the tapered portion 12 as it approaches the light incident surface 13 of the base 10.

[0027] A light incident surface 13 is provided at one end of the base 10 in the Y direction. In this embodiment, the light incident surface 13 is a plane that is substantially parallel to the XZ plane and extends in the X direction. This light incident surface 13 is used to allow light from a light source such as an LED (not shown) to enter the interior of the light guide plate 1.

[0028] Figure 2 This is a top view of the light guide plate of the first embodiment, viewed from the top surface. The light guide plate 1 of this embodiment is structurally divided into three regions R1, R2, and R3 arranged along the Y direction when viewed from above. The first region R1 is relatively close to the light incident surface 13, and is a portion located at a certain distance (e.g., several mm) in the Y direction, corresponding to the aforementioned tapered portion 12. The second region R2 is relatively far from the light incident surface 13 and is adjacent to the first region R1 in the Y direction. The third region R3 is adjacent to the second region R2 in the Y direction. Figure 2 For ease of explanation, the dimensions and size relationships may sometimes differ from those in the actual implementation. Additionally, the Y-direction length after region R3 is appropriately adjusted to correspond to the size of the display device described later.

[0029] In the first region R1, as described above, the height of each convex lens 11 is constant, while the bottom 14, which forms the upper surface of the conical portion 12, is inclined. Therefore, the closer each convex lens 11 is to the light incident surface 13 when viewed from above, the greater its apparent width (length in the X direction). Figure 2The region R1 gradually decreases in size, and at the same position as the light incident surface 13 (or at a certain distance from the light incident surface 13), the width becomes 0. In other words, the top view shape of each convex lens 11 within the first region R1 becomes an approximate triangular shape (or semi-elliptical shape) with one vertex at the position closest to the light incident surface 13.

[0030] In the second region R2, its upper surface is more gently inclined than that of the first region R1. As shown, bottoms 14 are arranged between each other in the X direction of each convex lens 11. These bottoms 14 extend along the Y direction when viewed from above, and their width (length in the X direction) decreases as they move away from the light incident surface 13, becoming 0 at the boundary between the second region R2 and the third region R3. Therefore, each bottom 14 forms a slender isosceles triangle shape when viewed from above, from the first region R1 to the second region R2.

[0031] In the third region R3, when viewed from above, the bottom 14 between each convex lens 11 is linear, and the lower ends of the convex lenses 11 are arranged in contact with each other in the X direction. Furthermore, the bottom 14 of region R3 is not tilted but parallel to the Y direction. This third region R3 is the region in the light guide plate 1 furthest from the light incident surface 13.

[0032] Figure 3 (A) is Figure 2 The partial cross-sectional view at line AA is shown. Figure 3 (B) is Figure 2 The partial cross-section at line BB is shown. Additionally... Figure 3 (C) is a diagram used to illustrate the ratio of each convex lens to the base. For example... Figure 3 As shown in (A), in the first region R1, the width d2 of the bottom 14 is relatively large relative to the width d1 of the convex lens 11. That is, the presence of the convex lens 11 is smaller. As a result, the light emission direction is extended. In other words, the light focusing ability in the vertical direction (Z direction) is reduced.

[0033] On the other hand, such as Figure 3As shown in (B), in the third region R3, the width d2 of the bottom 14 is 0, and the width d1 of the convex lens is relatively larger. That is, the presence ratio of the convex lens 11 is larger. As a result, the emission direction of the emitted light becomes narrower. In other words, it can also be said that the light focusing ability in the vertical direction is improved. In addition, although the figure is omitted, the light distribution characteristics in the second region R2 are intermediate between the light distribution characteristics of the first region R1 and the third region R. As for the second region R2 as a whole, the area ratio (presence ratio) of each convex lens 11 and each adjacent bottom 14 when viewed from above is preferably set between 6:4 and 9:1. According to the research of the inventors of this application, if the ratio of the bottom 14 is 4 or more (40% or more), the brightness of the emitted light decreases more; on the other hand, if the ratio of the bottom 14 is 1 or less (10% or less), the spreading effect of the emitted light becomes insufficient. That is, by ensuring that the area ratio (existence ratio) of each convex lens 11 and each adjacent bottom 14 when viewed from above is within the range described above, the brightness of the emitted light can be sufficiently maintained, and the brightness unevenness generated near the light incident surface 13 can be reduced.

[0034] Figure 4 (A) is Figure 2 The cross-sectional view at the CC line is shown. Furthermore, in Figure 4 In (A), to make the structure of the light guide plate 1 easier to understand, the thickness direction (Z direction) of the light guide plate 1 is shown enlarged compared to the actual dimensions. Furthermore, regarding the bottom 14 mentioned above, the bottom corresponding to the first region R1 is labeled as bottom 14a (first bottom), the bottom corresponding to the second region R2 is labeled as bottom 14b (second bottom), and the bottom corresponding to the third region R3 is labeled as bottom 14c (third bottom).

[0035] The angle (first tilt angle) between the bottom 14a of the upper surface of the cone-shaped portion 12 in the first region R1 and the Y direction is set as θ1. The tilt angle θ1 of the bottom 14a is constant from the starting point P0 to the inflection point (change point) P1 corresponding to the boundary of the first region R1 and the second region R2. The bottom 14a is tilted in such a way that the closer it is to the light incident surface 13, the greater its height relative to the lower surface of the base 10.

[0036] The angle between the bottom 14b of each convex lens 11 in the second region R2 and the Y direction, i.e., the tilt angle (second tilt angle), is set as θ2. This tilt angle θ2 is constant between the inflection point P1 and the inflection point P2. The inflection point P1 corresponds to the boundary between the first region R1 and the second region R2, and the inflection point P2 corresponds to the boundary between the second region R2 and the third region R3. That is, the tilt angle θ2 is constant throughout the second region R2. The bottom 14b is tilted in such a way that the closer it is to the light incident surface 13, the greater its height relative to the lower surface of the base 10. In addition, in the first embodiment, the bottom 14b as a whole corresponds to the "first surface".

[0037] In the third region R3, the bottom 14c exists in a linear form between each convex lens 11, and the linear bottom 14c is approximately parallel to the Y direction.

[0038] Figure 4 Figure (B) shows the top view of the bottom parts 14a and 14b in the first region R1 and the second region R2. As shown, the top view of the bottom part 14a is a slender isosceles triangle. Specifically, the bottom part 14a is a roughly trapezoidal shape with a wider width in the X direction as it gets closer to the light incident surface 13, and its two legs are curved. The bottom part 14b is also a slender isosceles triangle with a wider width in the X direction as it gets closer to the light incident surface 13, forming an inflection point P2.

[0039] Here, the tilt angles θ1 and θ2 are further explained. As described above, the tilt angles θ1 and θ2 are defined as angles formed with the Y direction. In this embodiment, the Y direction is parallel to the ridge line 11a of each convex lens 11 and also parallel to the lower surface of the base 10 of the light guide plate 1. Therefore, the tilt angles θ1 and θ2 can also be defined as angles formed with the ridge line 11a of each convex lens 11 or with the lower surface of the base 10 of the light guide plate 1. In this embodiment, the angle formed by the bottom 14, which is continuous from the first region R1 through the second region R2 to the third region R3, with the Y direction varies at two inflection points P1 and P2 when viewed in section. At this time, as shown in the figure, there is a relationship of θ1 > θ2 between each tilt angle θ1 and θ2. In other words, the bottom 14a located on the side close to the light incident surface 13 is tilted at an angle larger than that of the bottom 14b and bottom 14c, with the Y direction as the reference.

[0040] Here, based on the inventors' research, the tilt angle θ1 is preferably set in, for example, a range of 0.5° or more and 5° or less. Furthermore, the tilt angle θ2 is preferably set in, for example, a range of greater than 0° and 0.02° or less. Additionally, the Y-direction length y1 from the light incident surface 13 to the inflection point P1 is preferably set in, for example, a range of 0.1 mm or more and 5 mm or less, and the Y-direction length y2 from the light incident surface 13 to the inflection point P2 is preferably set in, for example, a range of 15 mm or more and 35 mm or less. As a preferred example, the tilt angle θ1 can be set to 2.7°, the tilt angle θ2 to 0.01°, the Y-direction length y1 to 0.3 mm, and the Y-direction length y2 to 20 mm.

[0041] Figure 5 Figure (A) is an example of the light emission distribution (i.e., the distribution of light emission positions as observed from the upper surface) of the light guide plate according to the first embodiment. Here, with the tilt angle θ1 set to 2.7°, the tilt angle θ2 set to 0.01°, the Y-direction length y1 set to 0.3 mm, the Y-direction length y2 set to 20 mm, and the overall length of the light guide plate in the Y-direction set to 180 mm, the light emission distribution of the light guide plate 1 in the Y-direction range of 0 mm to 30 mm was calculated by simulation. Furthermore, Figure 5 (B) is a light emission distribution diagram of the light guide plate in the comparative example. Here, instead of providing the first region R1 and the second region R2 as in the above embodiment, the entire upper surface of the light guide plate is configured to be the same as the third region R3 (d2 = 0; see reference). Figure 3 Case (B) is used as a comparative example. Furthermore, for any light guide plate, LEDs serving as light sources are provided at positions of 0mm and 5mm in the X direction. Additionally, the position at Y=0mm corresponds to the position of the light incident surface 13. Furthermore, the light exit positions are depicted as small dots in the diagram.

[0042] In the light guide plate 1 of this embodiment, compared with the light guide plate of the comparative example, the light output distribution in the Y direction, which has a length of about 0 to 5 mm and is close to the light source, is a gently expanding light distribution in the X direction in a trapezoidal shape. This is mainly due to the effect of the first region R1. As a result, the generation of the so-called hot spot phenomenon can be suppressed. Regarding this effect, if the tilt angle θ1 is greater than 5°, the effect tends to be too strong; if the tilt angle θ1 is less than 0.5°, the effect tends to be insufficient. In other words, if the tilt angle θ1 is greater than 5°, the light extraction function is enhanced to an excessive degree, and a hot spot phenomenon is generated directly above the light incident surface 13. On the other hand, if the tilt angle θ1 is less than 0.5°, the light extraction function is weakened, and the light emitted at the intersection between adjacent light sources is emphasized, which tends to generate a hot spot phenomenon. Therefore, the tilt angle θ1 is preferably set within the range of the above-mentioned numerical example. The hotspot phenomenon mentioned here refers to the phenomenon where, at the intersection of light rays traveling obliquely from adjacent point light sources through the light incident surface 13, the emitted light is emphasized, or the emitted light directly above the light incident surface 13 is emphasized, thus reducing aesthetics. According to the inventors' research, the hotspot phenomenon is suppressed primarily by reducing the light component traveling from the light source in a direction with an absolute value of 60° to 75° relative to the Y direction, mainly through the effect of the first region R1. Furthermore, by making the non-emitting area between light sources smaller, the unevenness of emitted light brightness can also be suppressed. Moreover, primarily through the effect of the second region R2, an extended light emission distribution in the X direction is obtained in the region where the Y value is 5 mm or more, i.e., in the region that should be the main light emission area in the light guide plate 1.

[0043] Figure 6 (A) is a schematic side view illustrating a structural example of a lighting device and a display device having the lighting device according to one embodiment. The illustrated display device 100 is configured to include a reflector 101, a light guide plate 102, a light source 103, a prism sheet 104, and a liquid crystal panel 105. The light guide plate 102 is the same as the light guide plate 1 in the above embodiment. The lighting device is configured by including the reflector 101, the light guide plate 102, the light source 103, and the prism sheet (light condenser) 104. In addition, the structure shown here is illustrative and does not preclude the addition of other structures.

[0044] The reflector 101 reflects light emitted from the lower surface of the light guide plate 102 back to the light guide plate 102. The light guide plate 102 guides light incident from the light source 103 and directs it to the upper surface side. The light source 103 is, for example, a semiconductor light-emitting element such as an LED or laser, which directs light into the light guide plate 102 from the incident surface at one end. The number of light sources 103 is not particularly limited, but at least two or more light sources 103 are arranged in the depth direction of the paper. Alternatively, the light source 103 can also be a fluorescent tube, a cold cathode tube, a hot cathode tube, an external electrode tube, an organic EL, an inorganic EL, etc. The prism sheet 104 focuses the light emitted from the upper surface side of the light guide plate 102. Alternatively, a light-concentrating sheet with the same focusing function can be used instead of the prism sheet 104. The liquid crystal panel 105 has multiple pixel areas (light modulation areas), and by arbitrarily increasing or decreasing the transmittance in each pixel area, an image based on the emitted light can be formed.

[0045] Figure 6 Figure (B) is a schematic top view illustrating the structure of the liquid crystal panel. As shown, the liquid crystal panel 105 includes: a display portion 105a, which is a portion containing the aforementioned plurality of pixel areas and contributing to image formation; and a peripheral portion 105b, which surrounds the display portion 105a in a ring shape. A driver or the like for driving the display portion 105a is disposed in the peripheral portion 105b. In the display device 100 of this embodiment, as... Figure 6 As shown in (A), a first region R1 of the light guide plate 102 is arranged at a position further outward than the display portion 105a of the liquid crystal panel 105 (see reference). Figure 2 The relative configuration relationship between the LCD panel 105 and the light guide plate 102 is set in a certain way.

[0046] According to the above-described embodiments, light guide plates, lighting devices, and display devices with reduced brightness unevenness can be obtained.

[0047] Furthermore, this disclosure is not limited to the embodiments described above, and various modifications can be made within the scope of the spirit of this disclosure. For example, the light guide plate 1 in the above embodiment has three regions R1-R3, but the third region R3 may be omitted. In this case, the second region R2 extends to the other end of the light guide plate 1. Moreover, the structure of the bottom of the light guide plate is not limited to the above embodiment. Several other embodiments will be described below.

[0048] Figure 7 (A) is a cross-sectional view of the light guide plate according to the second embodiment. This cross-sectional view is also similar to the one described above. Figure 4 (A) is similar to Figure 2The CC line shown corresponds to the actual thickness direction (Z direction) of the light guide plate, which is magnified. The light guide plate 1a of the second embodiment has an inflection point in the region of the bottom 14b in the second region R2, which differs from the first embodiment described above, but is otherwise the same. Specifically, the light guide plate 1a of the second embodiment adds an inflection point P3 between inflection point P1 and inflection point P2. Furthermore, the bottom 14b is arranged as a surface approximately parallel to the Y direction between inflection point P1 and inflection point P3, and is inclined at an angle θ2 with the Y direction as a reference between inflection point P3 and inflection point P2. In this second embodiment, the surface between inflection point P1 and inflection point P3 in the bottom 14b corresponds to the "third surface," and the surface between inflection point P3 and inflection point P2 corresponds to the "first surface."

[0049] Figure 7 (B) is a diagram showing the top view shape from the bottom of the first region R1 to the second region R2. The bottom 14a of the first region R1 has the same top view shape as in the embodiment described above. On the other hand, the bottom 14b of the second region R2 has a generally rectangular top view shape between the inflection point P1 and the inflection point P3, and an isosceles triangular shape between the inflection point P3 and the inflection point P2. Overall, it is a top view shape that connects the rectangle and the isosceles triangle in the Y direction. In this second embodiment of the light guide plate 1a, the same effect as the light guide plate 1 of the first embodiment can be obtained. In addition, similar to the light guide plate 1 of the first embodiment, it can be used as a component of a lighting device and a display device (see reference). Figure 6 (A)).

[0050] Figure 8 (A) is a cross-sectional view of the light guide plate according to the third embodiment. This cross-sectional view is also similar to the one described above. Figure 4 (A) is similar to Figure 2 The CC line shown corresponds to the actual thickness of the light guide plate (Z direction), which is magnified compared to the actual thickness. The light guide plate 1b of the third embodiment differs from the first embodiment in that it has two parts at its bottom 14b in the second region R2; otherwise, they are the same. Specifically, the light guide plate 1b of the third embodiment, like the light guide plate 1a of the second embodiment, adds an inflection point P3 between inflection point P1 and inflection point P2.

[0051] In the third embodiment, the bottom 14b is inclined at an angle θ3 with respect to the Y direction between inflection points P1 and P3, and inclined at an angle θ2 with respect to the Y direction between inflection points P3 and P2. Inflection points P1 and P2 have the same height in the Z direction, and the inflection angles θ2 and θ3 are also the same. The portion of the bottom 14b between inflection points P1 and P3 is inclined with increasing height along the Z direction, while the portion between inflection points P3 and P2 is inclined with decreasing height along the Z direction. Furthermore, in this third embodiment, the surface between inflection points P1 and P3 in the bottom 14b corresponds to the "second surface," and the surface between inflection points P3 and P2 corresponds to the "first surface."

[0052] Figure 8 (B) is a top view diagram showing the shape from the bottom of the first region R1 to the second region R2. The bottom 14a of the first region R1 is approximately triangular. This is because, at the inflection point P1, the convex lenses 11 are in contact with each other in the X direction, and d2 = 0. Furthermore, the bottom 14b of the second region R2 is an isosceles triangle with an acute angle on the left side of the diagram between inflection point P1 and inflection point P3, and an isosceles triangle with an acute angle on the right side of the diagram between inflection point P3 and inflection point P2. Overall, it is a rhomboid top view shape that is longer along the Y direction. In this third embodiment of the light guide plate 1b, the same effect as the first embodiment of the light guide plate 1 can be obtained. In particular, by setting the inflection point P1 where d2 = 0, the light extraction efficiency near the light incident surface (the portion at inflection point P1) is improved, and uneven brightness can be suppressed, thus improving the effect of suppressing hot spot phenomena. In addition, similar to the first embodiment of the light guide plate 1, it can be used as a component of a lighting device and a display device (see reference). Figure 6 (A)).

[0053] Figure 9 (A) is a cross-sectional view of the light guide plate according to the fourth embodiment. This cross-sectional view is also consistent with the above. Figure 4 (A) is similar to Figure 2The CC line shown corresponds to the actual thickness direction (Z direction) of the light guide plate, which is enlarged compared to the actual thickness. The light guide plate 1c of the fourth embodiment is a light guide plate in which a portion of the bottom 14 of the light guide plate 1a of the second embodiment is curved. Specifically, the bottom 14a of the first region R1 is curved from the starting point P0 to the inflection point P1. Furthermore, the bottom 14b of the second region R2 is curved from the inflection point P3 to the inflection point P2. In this fourth embodiment, the surface between the inflection point P1 and the inflection point P3 in the bottom 14b corresponds to the "third surface," and the surface between the inflection point P3 and the inflection point P2 corresponds to the "first surface." Although detailed descriptions are omitted, the bottom 14 can also be curved in the light guide plate 1 of the first embodiment, the light guide plate 1b of the third embodiment, and the light guide plate 1d of the fifth embodiment described later.

[0054] Figure 9 (B) Figure 9 Figure (C) is an example of a method for specifying the inclination angle of various surfaces. For example... Figure 9 As shown in (B), the tilt angle θ1 of the bottom 14a can be defined as the angle between the straight line connecting the starting point P0 and the inflection point P1 and the Y direction. Similarly, as Figure 9 As shown in (C), the tilt angle θ2 of the bottom 14a can be defined as the angle between the straight line connecting the inflection points P3 and P1 and the Y direction. Thus, the average tilt angle of each surface is obtained. In this fourth embodiment of the light guide plate 1c, the same effect as the light guide plate 1 of the first embodiment can be obtained. Furthermore, similar to the light guide plate 1 of the first embodiment, it can be used as a component of both a lighting device and a display device (see reference 1). Figure 6 (A)).

[0055] Figure 10 (A) is a cross-sectional view of the light guide plate according to the fifth embodiment. This cross-sectional view is also consistent with the above. Figure 4 (A) is similar to Figure 2The CC line shown corresponds to the actual thickness direction (Z direction) of the light guide plate, which is enlarged compared to the actual thickness. In the fifth embodiment, the light guide plate 1d, compared to the third embodiment's light guide plate 1b, has a newly provided fourth region R4 between the first region R1 and the second region R2. In this fourth embodiment, the bottom 14b is inclined at an angle θ3 with respect to the Y direction between inflection point P4 (corresponding to the boundary between the fourth region R4 and the second region R2) and inflection point P3, and inclined at an angle θ2 with respect to the Y direction between inflection point P3 and inflection point P2. The Z-direction heights of inflection points P1 and P2 are the same, and the inflection angles θ2 and θ3 are also the same. The portion of the bottom 14b between inflection points P4 and P3 is inclined with increasing height along the Z direction, and the portion between inflection points P3 and P2 is inclined with decreasing height along the Z direction. Furthermore, in the fourth region R4, the bottom 14d is arranged parallel to the Y direction between inflection points P1 and P4. Furthermore, in the bottom 14b of this fifth embodiment, the surface between inflection point P4 and inflection point P3 corresponds to the "second surface", the surface between inflection point P3 and inflection point P2 corresponds to the "first surface", and the surface between inflection point P1 and inflection point P4 corresponds to the "third surface".

[0056] Figure 10 (B) is a top view showing the shape from the bottom of the first region R1 to the second region R2. Except for the bottom 14d in the fourth region R4 being linear, it is the same as in the third embodiment. In the fourth region R4, the convex lenses 11 are in contact with each other in the X direction, d2 = 0, therefore the bottom 14d is linear. In this fifth embodiment of the light guide plate 1d, the same effect as the light guide plate 1 of the first embodiment can be obtained. In particular, by providing the fourth region R4, the light extraction efficiency near the light incident surface (part of the fourth region R4) is improved, and uneven brightness can be suppressed, thus improving the effect of suppressing hot spot phenomena. Furthermore, similar to the light guide plate 1 of the first embodiment, it can be used as a component of an illumination device and a display device (see reference). Figure 6 (A)).

[0057] Marker description

[0058] 1: Light guide plate; 10: Base; 11: Convex lens; 12: Conical portion; 13: Incident surface; 14, 14a, 14b, 14c: Bottom; 100: Display device; 101: Reflector; 102: Light guide plate; 103: Light source; 104: Prism sheet; 105: Liquid crystal panel; R1: First region; R2: Second region; R3: Third region

Claims

1. A light guide plate, comprising: The base has a surface and a light incident surface that is arranged intersecting the surface at one end; as well as Multiple convex lenses are disposed on the side of the base opposite to the first surface, extending along a first direction and arranged along a second direction substantially orthogonal to the first direction. The base includes at least a first region relatively close to the light incident surface and a second region relatively far from the light incident surface. A plurality of first bottoms are disposed in the first region. The plurality of first bottoms are respectively disposed on the surfaces between adjacent convex lenses in the second direction, and are disposed at an angle relative to the first direction. The plurality of first bottoms each have a top-view shape in which the width in the second direction increases the closer they are to the light incident surface.

2. The light guide plate according to claim 1, wherein, The plurality of first bottoms are respectively arranged at an angle such that the closer they are to the light incident surface, the greater their height relative to one of the surfaces of the base portion.

3. The light guide plate according to claim 1 or 2, wherein, The angle formed by each of the plurality of first bottoms with the first direction, i.e., the first tilt angle, is greater than 0.5° and less than 5°.

4. A light guide plate, comprising: The base has a surface and a light incident surface that is arranged intersecting the surface at one end; as well as Multiple convex lenses are disposed on the side of the base opposite to the first surface, extending along a first direction and arranged along a second direction substantially orthogonal to the first direction. The base includes at least a first region relatively close to the light incident surface and a second region relatively far from the light incident surface. A plurality of first bottoms are disposed in the first region. The plurality of first bottoms are respectively disposed on the surfaces between adjacent convex lenses in the second direction, and are disposed at an angle relative to the first direction. A plurality of second bottoms are disposed in the second region, the plurality of second bottoms being respectively disposed on the surfaces between adjacent convex lenses in the second direction. Each of the plurality of second bottoms has at least one first surface that is tilted in such a way that the height relative to the light incident surface is greater the closer it is to the light incident surface.

5. The light guide plate according to claim 4, wherein, The plurality of first bottoms are respectively arranged at an angle such that the closer they are to the light incident surface, the greater their height relative to one of the surfaces of the base portion.

6. The light guide plate according to claim 4 or 5, wherein, The angle between the first surface of each of the plurality of second bottoms and the first direction, i.e., the second tilt angle, is smaller than the angle between each of the plurality of first bottoms and the first direction, i.e., the first tilt angle.

7. The light guide plate according to claim 6, wherein, The first tilt angle is greater than 0.5° and less than 5°.

8. The light guide plate according to claim 4 or 5, characterized in that, The area ratio of each of the plurality of second bottoms to the convex lens adjacent to each of the second bottoms when viewed from above is set between 4:6 and 1:

9.

9. The light guide plate according to claim 4 or 5, characterized in that, Each of the plurality of second bottoms also has a third surface configured substantially parallel to the first direction and / or a second surface configured obliquely in such a way that the height of the second surface relative to the first surface of the base portion is smaller the closer it is to the light incident surface.

10. The light guide plate according to claim 4 or 5, characterized in that, The plurality of first bottoms each have a top-view shape in which the width in the second direction increases the closer they are to the light incident surface.

11. A lighting device comprising: The light guide plate according to any one of claims 1 to 10; A reflective sheet is disposed on one side of the light guide plate; A light-concentrating sheet, disposed on the light-emitting side of the light guide plate; and Multiple light sources are arranged opposite to the light incident surface of the light guide plate.

12. A display device comprising: The lighting device according to claim 11; as well as A liquid crystal panel is disposed on the light-emitting side of the lighting device.

13. The display device according to claim 12, wherein, The liquid crystal panel has a display portion that contributes to image formation and a peripheral portion that surrounds the display portion in a ring shape. The light guide plate is configured such that the first region is located outside the display portion of the liquid crystal panel.

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