Light guide plate and lighting device

Abstract

A light guide plate and a lighting device, wherein the light guide plate (30) comprises: a first main surface (33); a side end surface arranged at an end in a first direction along the first main surface (33); and a first end surface (31) arranged at an end in a second direction along the first main surface (33) and intersecting the first direction, for light emitted by a light source to be incident. A plurality of elongated prisms (37) having the first direction as the length direction are arranged on the first main surface (33). When the angle formed by the side surface on the light source (20) side of the elongated prism (37) and the main surface is assumed to be a control angle, the first prism group arranged along the first direction among the plurality of elongated prisms (37) includes elongated prisms (37) having different control angles.

Description

Technical Field

[0001] The present invention relates to a light guide plate and a lighting device having the light guide plate. Background Art

[0002] Various devices using light guide plates have been proposed. For example, Patent Document 1 discloses a light guide plate capable of switching display styles depending on which of the light sources is turned on even when a plurality of light sources are arranged only on one end of the light guide plate, and a gaming machine having the light guide plate.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2016-122162 Summary of the invention

[0006] Problems to be solved by the invention

[0007] The invention provides a light guide plate and a lighting device capable of reducing uneven brightness of an irradiated surface.

[0008] Means used to solve problems

[0009] A light guide plate according to one embodiment of the present invention comprises: a main surface; a side end surface, which is arranged at an end portion in a first direction along the above-mentioned main surface; and an end surface, which is arranged at an end portion in a second direction along the above-mentioned main surface and intersecting with the above-mentioned first direction, for incident light emitted by a light source; a plurality of elongated prisms having the above-mentioned first direction as a length direction are arranged on the above-mentioned main surface; when the angle formed by the side surface on the above-mentioned light source side of the above-mentioned elongated prism and the above-mentioned main surface is assumed to be a control angle, a first prism group arranged along the above-mentioned first direction among the plurality of the above-mentioned elongated prisms includes the above-mentioned elongated prisms having different control angles from each other.

[0010] A lighting device according to one aspect of the present invention includes the above-mentioned light guide plate and the above-mentioned light source.

[0011] Effects of the Invention

[0012] A light guide plate and a lighting device according to one aspect of the present invention can reduce uneven brightness of an irradiated surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is an appearance diagram of a lighting device according to an embodiment.

[0014] Figure 2 It is a cross-sectional view of a lighting device according to an embodiment.

[0015] Figure 3 It is a diagram showing the arrangement of a light source and a light guide plate of a lighting device according to an embodiment.

[0016] Figure 4 It is a diagram showing the arrangement of the long prisms in the light guide plate according to the comparative example.

[0017] Figure 5 The figure shows the position of the long prism and the schematic optical path of the light emitted from the light source.

[0018] Figure 6 This is a diagram showing the simulation results of the light distribution characteristics of light reflected by the long prism.

[0019] Figure 7 It is a diagram showing four types of brightness distribution on the illuminated surface.

[0020] Figure 8 It is a diagram showing the brightness distribution in the Y-axis direction of the irradiation surface facing the light guide plate according to the comparative example.

[0021] Fig. 9 It is a diagram showing the brightness distribution in the Y-axis direction of the irradiation surface facing the light guide plate according to the embodiment.

[0022] Fig.10 It is a diagram showing an arrangement example 1 of the strip prisms.

[0023] Fig.11 It is a diagram showing an arrangement example 2 of the strip prisms.

[0024] Fig.12 FIG. 1 is a first diagram showing a third configuration example of the long prisms.

[0025] Fig.13 FIG. 2 is a second diagram showing an arrangement example 3 of the long prisms.

[0026] Fig.14 FIG. 3 is a third diagram showing an arrangement example 3 of the long prisms.

[0027] Fig.15 It is a diagram showing an arrangement example 4 of the strip prisms.

[0028] Fig.16 It is a diagram showing an arrangement example 5 of the strip prisms.

[0029] Fig.17 It is a diagram showing an arrangement example 6 of the strip prisms.

[0030] Fig.18 It is a diagram showing a modified example of the arrangement example 6 of the long prisms.

[0031] Fig.19 It is a diagram showing an arrangement example 7 of the long prisms.

[0032] Fig. 20 It is a diagram showing an arrangement example 8 of the long prisms.

[0033] Fig.21 This is a diagram for explaining how to determine the width of a grid.

[0034] Fig. 22 It is a diagram showing a modified example of the light source.

[0035] Description of Reference Numerals

[0036] 10 lighting device; 20 light source; 21 substrate; 22 light emitting element; 30, 30a~30k, 30z light guide plate; 31 first end face; 32 second end face; 33 first principal face; 34 second principal face; 35 first side end face; 36 second side end face; 37 long prism; 37a, 38a prism array; 38 conical continuous prism; 40 light-transmitting cover; 50 reflecting plate; 60 housing; 70 retaining portion; 80 end face cover; 91 wall surface; 92 ceiling surface. DETAILED DESCRIPTION

[0037] Below, while referring to the attached Figure 1 The embodiments are described below. The embodiments described below are all inclusive or specific examples. The numerical values, shapes, materials, components, configurations of components, and connection forms shown in the following embodiments are examples, and the main purpose is not to limit the present invention. In addition, the components of the following embodiments that are not recorded in the independent claims representing the highest concept of the present invention are described as arbitrary components.

[0038] In addition, each figure is a schematic diagram and is not necessarily a strict illustration. In addition, in each figure, the same reference numerals are given to substantially the same structure, and there are cases where repeated descriptions are omitted or simplified. In addition, in the following embodiments, the expression "same" does not mean the same in a strict sense, but means substantially the same. Substantially the same means, for example, the same within the range including manufacturing errors or dimensional tolerances.

[0039] In addition, in the following embodiments, coordinate axes are shown in the drawings used for explanation. The Z-axis direction is assumed to be the thickness direction of the light guide plate for explanation. In addition, the X-axis direction and the Y-axis direction are directions orthogonal to each other on a plane perpendicular to the Z-axis direction. In the following embodiments, the plan view refers to observation from the Z-axis direction.

[0040] (Implementation Method)

[0041] [lighting device]

[0042] Hereinafter, a lighting device according to an embodiment will be described. Figure 1 It is an appearance diagram of a lighting device according to an embodiment.

[0043] like Figure 1 As shown, the lighting device 10 of the embodiment is a bracket light. Figure 1 In the embodiment, the lighting device 10 is installed on the wall surface 91 to irradiate light toward the ceiling surface 92, but it may be installed on the wall surface 91 to irradiate light toward the ground.

[0044] Next, the internal structure of such lighting device 10 will be described. Figure 2 is a cross-sectional view of the lighting device 10. Figure 2 As shown, the lighting device 10 includes a light source 20 , a light guide plate 30 , a light-transmitting cover 40 , a reflection plate 50 , and a housing 60 .

[0045] First, refer to Figure 2 as well as Figure 3 The light source 20 and the light guide plate 30 will be described. Figure 3 It is a diagram showing the arrangement of the light source 20 and the light guide plate 30 . Figure 3 (a) is a diagram of the light source 20 and the light guide plate 30 observed from the X-axis direction. Figure 3 (b) is a diagram of the light source 20 and the light guide plate 30 observed from the Z-axis direction. Figure 3 (c) is a diagram of the light source 20 and the light guide plate 30 as viewed from the Y-axis direction.

[0046] The light source 20 is located on the side of the light guide plate 30 and is a light emitting module that emits light toward the first end surface 31 of the light guide plate 30. The light source 20 includes a substrate 21 and a light emitting element 22.

[0047] The substrate 21 is a long rectangular substrate that is long in the X-axis direction in the figure. The long side direction of the substrate 21 is the X-axis direction, and the short side direction of the substrate 21 is the Z-axis direction. The substrate 21 is arranged parallel to the first end surface 31 of the light guide plate 30. In addition, the shape of the substrate 21 is not particularly limited.

[0048] Specifically, the substrate 21 is a rigid substrate such as a resin substrate, a ceramic substrate, or a metal base substrate.

[0049] The mounting surface, which is a main surface of the substrate 21 on which the plurality of light emitting elements 22 are mounted, faces the first end surface 31 of the light guide plate 30. The plurality of light emitting elements 22 are arranged in a row along the longitudinal direction of the substrate 21.

[0050] The light emitting element 22 is a surface mount type (SMD type) LED element that emits white light. The surface mount type LED element is a package type LED element in which an LED chip is mounted in a cavity molded by resin and a phosphor-containing resin is sealed in the cavity. The light emitting element 22 emits white light such as daylight color to incandescent color (color temperature of 2600K or more and 7100K or less) toward the first end surface 31 of the light guide plate 30 located in front of the light emitting element 22.

[0051] The light source 20 is electrically connected to a power circuit (not shown) in the housing 60 via a cable (not shown), and emits light using power supplied from the power circuit.

[0052] The light guide plate 30 is an optical component having a rectangular flat plate shape when viewed from the Z-axis direction, in other words, a light guide. The light guide plate 30 is a transparent component, but any component having light transmittance may be used. The light guide plate 30 is formed of, for example, acrylic resin, but may also be formed of polycarbonate resin or glass.

[0053] The light guide plate 30 has a first end surface 31 , a second end surface 32 , a first main surface 33 , a second main surface 34 , a first side end surface 35 , and a second side end surface 36 .

[0054] The first end surface 31 is an end surface provided at the end in the Y-axis direction of the light guide plate 30, and is an end surface on which the light emitted by the light source 20 is incident, and is, for example, a plane. The second end surface 32 is an end surface provided at the end in the Y-axis direction of the light guide plate 30, and is located on the opposite side of the first end surface 31 (i.e., the end surface facing away from the first end surface 31), and is, for example, a plane.

[0055] The first principal surface 33 is a principal surface provided with a reflective structure that reflects light incident on the first end surface 31 toward the second principal surface 34. A plurality of fine elongated prisms 37 are provided on the first principal surface 33 as the reflective structure.

[0056] The elongated prism 37 is a concave portion provided on the first principal surface 33, but may also be a convex portion. In the figure, the elongated prism 37 is shown larger for the purpose of explanation, but is actually small. The length of the elongated prism 37 is, for example, about 4 mm. The elongated prism 37 has the X-axis direction as its length direction. In other words, the X-axis direction is the first direction along the first principal surface 33, and is a direction perpendicularly intersecting the second direction (Y-axis direction) in which the first end face 31 and the second end face 32 are arranged.

[0057] like Figure 3 As shown in (a), the elongated prism 37 is a long groove having a substantially V-shaped cross section. When the angle θ1 formed between the side surface of the elongated prism 37 on the light source 20 side and the first main surface 33 is defined as a control angle, a plurality of prisms having different control angles are provided on the first main surface 33. Figure 3 In (b), the elongated prisms 37 of different colors represent prisms with different control angles. The same is true in the following figures.

[0058] The figure shows three kinds of long prisms 37 with different control angles, but in fact, there are about 10 to 20 kinds of long prisms 37 with different control angles on the first main surface 33. The difference in control angles of the long prisms 37 with different control angles is, for example, greater than 1° and less than 55°. Specifically, in the combination with a smaller control angle difference, the difference is about 1°, and in the combination with a larger control angle difference, the difference exceeds 50°. The cross-sectional shape of the long prism 37 can be a symmetrical shape (that is, in Figure 3 In (a), θ1=θ2), but by satisfying θ1<θ2, the light extraction efficiency can be improved. The elongated prisms 37 are formed on the first main surface 33 by thermal processing such as laser processing, for example.

[0059] Compared with a conical prism, the side surface (in other words, the control surface) of the elongated prism 37 on the light source 20 side (the first end surface 31 side) is larger in area, so the light control efficiency is high and the light distribution controllability is excellent. The elongated prism 37 can effectively realize a wide light distribution characteristic in the X-axis direction.

[0060] The second main surface 34 is a main surface located on the opposite side of the first main surface 33 (i.e., a main surface facing away from the first main surface 33). The second main surface 34 is a plane. No reflective structure is provided on the second main surface 34, but a plurality of elongated prisms 37 may be provided as a reflective structure as on the first main surface 33.

[0061] The first side end surface 35 is an end surface provided at the end in the X-axis direction of the light guide plate 30. The second side end surface 36 is an end surface provided at the end in the X-axis direction of the light guide plate 30 and located on the opposite side of the first side end surface 35 (i.e., the side end surface facing away from the first side end surface 35).

[0062] Next, the light-transmitting cover 40 will be described. The light-transmitting cover 40 is arranged so as to face the second main surface 34 of the light guide plate 30. The light-transmitting cover 40 constitutes the outer shell of the lighting device 10 and functions as an outlet for light emitted from the light guide plate 30. The base of the light-transmitting cover 40 is formed of, for example, acrylic resin, but may also be formed of polycarbonate resin or glass.

[0063] The light-transmitting cover 40 is a cover that transmits light emitted from the light guide plate 30. The light-transmitting cover 40 may have a function (light diffusion function) of diffusing light emitted from the light guide plate 30. For example, the light-transmitting cover 40 may have a light diffusion function by including a light diffusion material such as silicon dioxide in the base.

[0064] Next, the reflector 50 will be described. The reflector 50 is a flat plate-shaped member having a rectangular shape in a plan view. The reflector 50 is arranged in such a manner that the reflective surface faces the first main surface 33. The reflector 50 is formed of, for example, a metal material having light reflectivity such as aluminum, and the surface facing the first main surface 33 is a mirror surface. Alternatively, the reflector 50 may be formed of a white resin material, a resin material with a metal film attached, a resin material coated with white, or a metal material coated with white. According to the reflector 50, the lighting device 10 can be provided with a single-sided reflector (on one side or the other). Fig.10 In the example, the light is effectively emitted from the Z-axis side. In addition, the plan view shape of the reflector 50 is not limited to a rectangle, and may be other shapes.

[0065] Next, the housing 60 will be described. The housing 60 holds a light source unit including the light source 20, the light guide plate 30, and the reflector 50, and the light-transmitting cover 40. In addition to the light source 20, the light guide plate 30, and the reflector 50, the light source unit further includes a holding portion 70 and an end face cover 80, wherein the light source 20 and the light guide plate 30 are integrally held by the holding portion 70, and the reflector 50 is pressed against the light guide plate 30 by the end face cover 80. In addition, the housing 60 constitutes the outer contour of the lighting device 10. The housing 60 is formed of, for example, a metal material, but may also be formed of a resin material.

[0066] [Configuration of strip prism]

[0067] The lighting device 10 reduces the irradiation surface (in Figure 1 In the example of FIG. 1 , the brightness unevenness is on the ceiling surface 92. Hereinafter, the light guide plate 30 provided in the lighting device 10 is compared with the light guide plate of the comparative example, and the reason why the brightness unevenness is reduced is described. Figure 4 It is a diagram showing the arrangement of the elongated prisms 37 of the light guide plate according to the comparative example.

[0068] As mentioned above Figure 3 As shown in (b), in the light guide plate 30, among the plurality of elongated prisms 37, the first prism group arranged along the X-axis direction includes elongated prisms 37 having different control angles. Figure 3 In the example (b), the first prism group composed of five elongated prisms 37 arranged in the X-axis direction includes three types of elongated prisms 37 having different control angles.

[0069] On the other hand, Figure 4 As shown, in the light guide plate 30z of the comparative example, the first prism group arranged along the X-axis direction among the plurality of elongated prisms 37 includes only elongated prisms 37 having the same control angle, and the second prism group arranged along the Y-axis direction includes elongated prisms 37 having different control angles.

[0070] Compared with the light guide plate 30z in the comparative example, the light guide plate 30 can reduce the brightness unevenness of the illumination surface. To explain the reason, first, the distance from the light source 20 to the long prism 37 and the light distribution characteristics of the light reflected by the long prism 37 will be described. Figure 5 It is a diagram showing the position of the long prism 37 and the schematic optical path of the light emitted from the light source 20. Figure 6 It is a diagram showing the simulation result of the light distribution characteristics of the light reflected by the long prism 37. Figure 6 It shows the simulation result corresponding to the distance from the group of long prisms 37 closest to the light source 20 to any group of long prisms 37 in the Y direction. Figure 5 The positions (1), (2), (3),... of the group of long prisms 37 shown correspond to Figure 6 the series (1), (2), (3),... of the curve graph. The positions (1), (2), (3), (4), (5) of the group of long prisms 37 are equally spaced.

[0071] As Figure 5 shown, the light with a larger emission angle with respect to the optical axis of the light source 20 is reflected by the group of long prisms 37 near the light source 20 and is less likely to reach the group of long prisms 37 farther from the light source 20. As a result, as Figure 6 shown, the closer the group of long prisms 37 is to the light source 20, the more the amount of reflected light. In addition, the position of the peak of the light distribution characteristics also changes. In Figure 6 , the peak of the light distribution characteristics of the group of long prisms 37 set at the position (1) is located near 220°, but the peak of the light distribution characteristics of the group of long prisms 37 set at the position (5) is located near 225°.

[0072] In view of the results of such simulations, it is assumed that the brightness distribution of the illumination surface corresponds to the position of the long prism 37 and the control angle of the long prism 37 as Figure 7 shown. Figure 7 It is a diagram showing four brightness distributions (NA, NB, FA, FB) of the illumination surface. In Figure 7 , the vertical axis represents the brightness and the horizontal axis represents the position of the illumination surface in the Y-axis direction.

[0073] NA is the brightness distribution achieved by the long prism 37 with a control angle of A and set at a position N closer to the light source 20. NB is the brightness distribution achieved by the long prism 37 with a control angle of B (in the example of Figure 7 , B < A) and set at the position N. In addition, FA is the brightness distribution achieved by the long prism 37 with a control angle of A and set at a position F farther from the light source 20, and FB is the brightness distribution achieved by the long prism 37 with a control angle of B and set at the position F. Also, the position N and the position F are in Figure 3 (b) and Figure 4 Indicated by dotted line.

[0074] As mentioned above Figure 4 As shown, for the light guide plate 30z of the comparative example, the first prism group arranged along the X-axis direction only includes the long strip prisms 37 having the same control angle. For the light guide plate 30z of the comparative example, at the position N closer to the light source 20, only one type of long strip prism 37 (for example, the long strip prism 37 having the control angle A) is provided, and at the position F farther from the light source 20, only one type of long strip prism 37 (for example, the long strip prism 37 having the control angle B) is also provided.

[0075] Therefore, the brightness distribution in the Y-axis direction of the irradiation surface opposite to the light guide plate 30z, which is realized by the long prism 37 set at the position N and the long prism 37 set at the position F, is as shown in FIG. Figure 8 As indicated by the dotted line in FIG. 1 , it has a shape obtained by adding NA to FB. Figure 8 It is a diagram showing the brightness distribution in the Y-axis direction of the irradiation surface facing the light guide plate 30z according to the comparative example.

[0076] In contrast, as mentioned above Figure 3 As shown in (b), for the light guide plate 30, the first prism group arranged along the X-axis direction includes elongated prisms 37 with different control angles. Specifically, for the light guide plate 30, a plurality of elongated prisms 37 (for example, elongated prisms 37 with control angle A and elongated prisms 37 with control angle B) are arranged at a position N closer to the light source 20. For the light guide plate 30, a plurality of elongated prisms 37 (for example, elongated prisms 37 with control angle A and elongated prisms 37 with control angle B) are also arranged at a position F farther from the light source 20. Such a configuration of elongated prisms 37 can be said to be less susceptible to Figure 6 The arrangement is affected by the difference in light distribution characteristics of the elongated prisms 37 due to the distance from the light source 20 to the elongated prisms 37 described in .

[0077] Therefore, the brightness distribution in the Y-axis direction of the irradiation surface opposite to the light guide plate 30, which is realized by the long prism 37 set at the position N and the long prism 37 set at the position F, is as shown in FIG. Fig. 9 As indicated by the dotted line in FIG. 1 , it has a shape obtained by adding NA, NB, FA, and FB. Fig. 9 It is a diagram showing the brightness distribution in the Y-axis direction of the irradiation surface facing the light guide plate 30 .

[0078] Fig. 9 The brightness distribution shown is similar to Figure 8That is, the light guide plate 30 can reduce the unevenness of the brightness of the irradiated surface compared with the light guide plate 30z.

[0079] [Arrangement example 1 of strip prism]

[0080] Next, other arrangement examples of the elongated prisms 37 will be described. Fig.10 It is a diagram showing an arrangement example 1 of the elongated prisms 37 .

[0081] exist Figure 3 In the light guide plate 30 shown in FIG. 1 , the first prism group arranged along the first direction includes elongated prisms 37 having different control angles, and the second prism group arranged along the second direction includes elongated prisms 37 having the same control angle. Fig.10 In the light guide plate 30a shown, not only the first prism group includes the elongated prisms 37 having control angles different from each other, but also the second prism group includes the elongated prisms 37 having control angles different from each other.

[0082] When the second prism group arranged along the second direction includes only the elongated prisms 37 with high light extraction efficiency (e.g., prisms with a large control angle), light is extracted on the side of the elongated prisms 37 arranged along the second direction of the light guide plate 30 relative to the light source 20, and the light extraction from the elongated prisms 37 on the emission end surface (second end surface 32) side is reduced, so that the prism drawing area of ​​the light guide plate 30 may not be effectively used. On the other hand, when the second prism group arranged along the second direction includes only the elongated prisms 37 with low light extraction efficiency (e.g., prisms with a small control angle), light is not completely extracted between the prisms arranged along the second direction of the light guide plate 30, the guided light reaches the second end surface 32, and the light extraction amount from the second main surface 34 is reduced. When there is unevenness in the light extraction of the light guide plate 30 as described above, the light extraction efficiency of the light guide plate 30 as a whole may be reduced.

[0083] On the other hand, by including the elongated prisms 37 having different control angles in the second prism group as in the light guide plate 30 a , the above-mentioned unevenness is improved, and the light extraction efficiency of the light guide plate 30 a as a whole is improved.

[0084] In addition, the light incident on the strip prism 37 disposed at a position away from the light source 20 includes light whose light path is disturbed by the strip prism 37 located on the side closer to the light source 20 than the strip prism 37. Therefore, as in the light guide plate 30a, by including not only the strip prisms 37 with different control angles in the first prism group but also the strip prisms 37 with different control angles in the second prism group, the light path is easily scattered. If the light path is scattered, the light extraction method changes, and the width of the brightness distribution of the light extracted from the various strip prisms 37 can be expanded. When the brightness distribution of light with a wider width is combined, the brightness distribution is smoothly connected, and the brightness unevenness of the irradiated surface is reduced.

[0085] [Arrangement example 2 of strip prisms]

[0086] Fig.11 37 is a diagram showing a second configuration example of the long prism 37. Figure 3 ) and light guide plate 30a( Fig.10 ) in which a plurality of long prisms 37 are arranged in a matrix, but in Fig.11 In the light guide plate 30 b shown, a plurality of long prisms 37 are arranged in a staggered pattern (staggered pattern, houndstooth pattern).

[0087] In the matrix arrangement, a linear region (for example, Fig.10 In contrast, in the light guide plate 30b, since such a linear region is not provided, the light emitted by the light source 20 is prevented from being reflected by the long prism 37 and reaching the second end surface 32. In other words, the possibility of the light emitted by the light source 20 being reflected by the long prism 37 becomes higher, which can improve the light extraction efficiency.

[0088] In addition, if Fig.11 As shown, in the staggered arrangement, a strip prism shorter than the usual strip prism 37 may be provided at the end in the X-axis direction. Figure 3 , Fig.10 , Fig.11 In any arrangement, it can be said that the plurality of elongated prisms 37 are aligned in the X-axis direction and the Y-axis direction. Thus, the aesthetics of the light emitting surface of the light guide plate 30 (or the light guide plate 30a, the light guide plate 30b) is improved.

[0089] [Arrangement example 3 of strip prism]

[0090] A plurality of grids may be provided on the first main surface 33 , and the grids are regions where the elongated prisms 37 having the same control angle are uniformly arranged. Figure 12 to Figure 14 This is a diagram showing an example in which the elongated prisms 37 are arranged in grid units (arrangement example 3 of the elongated prisms 37 ).

[0091] exist Figure 12 to Figure 14 In the light guide plates 30c, 30d and 30e shown, the regions divided by dotted lines are grids. In one grid, a plurality of long prisms 37 having the same control angle are provided. A plurality of grids are arranged in the X-axis direction and the Y-axis direction.

[0092] The total number of grids, the size of the grids, and the shape of the grids are not particularly limited. Fig.12 The light guide plate 30c and Fig.13 As shown in the light guide plate 30d, the plurality of grids include grids of different shapes and sizes. Fig.14 As shown in the light guide plate 30e, the shapes and sizes of the plurality of grids are substantially uniform.

[0093] In this way, if the control angles are unified in grid units, the optical design by the designer becomes easier. In addition, since a plurality of elongated prisms 37 belonging to one grid can be formed together in one process, the time required for processing is shortened.

[0094] In addition, if the magnitude relationship of the control angle is changed in small intervals in the grid unit in the X-axis direction, the light extraction efficiency of the light obliquely guided from the light source 20 toward the second end surface 32 can be improved. That is, by setting the control angle of the elongated prism 37 belonging to the central grid among the three grids arranged continuously along the X-axis direction to be larger than the control angle of the elongated prism 37 belonging to the other two grids among the three grids, or setting the control angle of the elongated prism 37 belonging to the other two grids among the three grids to be smaller than the control angle of the elongated prism 37 belonging to the other two grids among the three grids, the light extraction efficiency can be improved.

[0095] In addition, if the size relationship of the control angle is changed in small intervals in the Y-axis direction in grid units, the effects of reducing uneven brightness of the irradiated surface, improving the accuracy of the optical design, and making light extraction uniform can be obtained. In addition, since the pattern of the long prism 37 looks like a pattern, the pattern attracts the eye, so the sense of incongruity in the appearance caused by the processing deviation of the long prism 37 can be reduced. That is, by setting the control angle of the long prism 37 belonging to the central grid of the three grids arranged continuously along the Y-axis direction to be larger than the control angle of the long prism 37 belonging to the other two grids of the three grids, or smaller than the control angle of the long prism 37 belonging to the other two grids of the three grids, the above-mentioned effect can be obtained.

[0096] [Arrangement example 4 of strip prisms]

[0097] Fig.15 37 is a diagram showing a fourth configuration example of the long prism 37. Fig.15 In the figure, the long prisms 37 have different colors, and the darker the color, the larger the control angle. Fig.15 In the light guide plate 30f shown in FIG. 1 , the arrangement of the long prisms 37 with the same control angle is bilaterally symmetrical. Fig.15 The arrangement of the black strip prisms 37 is symmetrical about the second imaginary straight line L2. The arrangement of the dark gray strip prisms 37, the arrangement of the light gray strip prisms 37, and the arrangement of the white strip prisms 37 are also symmetrical about the second imaginary straight line L2. In addition, the second imaginary straight line L2 is an imaginary straight line that bisects the first main surface 33 along the Y-axis direction.

[0098] Such a light guide plate 30f can realize symmetrical light distribution in the X-axis direction (left-right direction), and can reduce uneven brightness in the X-axis direction of the irradiated surface.

[0099] [Arrangement example 5 of strip prisms]

[0100] Fig.16 It is a diagram showing a fifth arrangement example of the elongated prisms 37 . Fig.16 In the figure, the long prisms 37 have different colors, and the darker the color, the larger the control angle. Fig.16 In the light guide plate 30g shown, when the first main surface 33 is divided into the first region R1 and the second region R2 on the light source 20 side by the first imaginary straight line L1 along the X-axis direction, the average value of the control angles of the elongated prisms 37 provided in the first region R1 is smaller than the average value of the control angles of the elongated prisms 37 provided in the second region R2. That is, in the light guide plate 30g, the control angles of the elongated prisms 37 increase, on average, as they are farther from the light source 20.

[0101] Thus, by arranging the long prism 37 with a small control angle that generates wide light at a position on the light source 20 side with a high light extraction efficiency, the wide light can be effectively extracted. By arranging the long prism 37 with a large control angle at a position on the second end surface 32 side, the light incident on the long prism 37 at a shallow angle can be effectively extracted, and the light extraction amount of the entire light guide plate 30g can be increased.

[0102] [Arrangement example 6 of strip prisms]

[0103] Fig.17 FIG. 6 is a diagram showing an example 6 of the arrangement of the long prism 37. Fig.17 The light guide plate 30h shown in the figure is provided with not only the long prism 37 but also the conical continuous prism 38. The conical continuous prism 38 is a prism formed by connecting conical prisms (conical concave or convex parts) in the X-axis direction by a length corresponding to the length direction of the long prism 37. The number of conical prisms included in one conical continuous prism 38 is not particularly limited.

[0104] In the light guide plate 30h, a configuration is adopted in which a part of the long prisms 37 is replaced by the conical continuous prisms 38 in a staggered configuration like the light guide plate 30b, but a configuration may be adopted in which a part of the long prisms 37 is replaced by the conical continuous prisms 38 in a matrix configuration like the light guide plate 30 or the light guide plate 30a. The conical continuous prisms 38 may be appropriately arranged at which position based on experience or experimentation. Fig.18 6 is a diagram showing a modified example of the configuration example 6 of the long prism. Fig.18 As shown in the light guide plate 30i, all the long prisms 37 existing in the grid are replaced with conical continuous prisms 38.

[0105] The light distribution characteristics of the conical continuous prism 38 are greatly different from those of the strip prism 37. If the conical continuous prism 38 having light distribution characteristics greatly different from those of the strip prism 37 is provided, a brightness distribution of the irradiated surface that cannot be achieved by the strip prism 37 alone can be achieved. As a result, uneven brightness of the irradiated surface is reduced.

[0106] Furthermore, although, for example, one type of conical continuous prism 38 is provided on the first principal surface 33 of the light guide plate 30 h or the light guide plate 30 i , a plurality of types of conical continuous prisms 38 having different control angles may be provided.

[0107] [Arrangement example 7 of strip prisms]

[0108] Fig.19 37 is a diagram showing an example 7 of the arrangement of the long prism 37. Fig.19 In the light guide plate 30j shown, the prism row 38a composed of a plurality of conical continuous prisms 38 arranged along the X-axis direction is provided at a position (Y-axis direction) closest to the light source 20 among the prisms provided on the first main surface 33. In other words, the plurality of conical continuous prisms 38 arranged along the X-axis direction are located closest to the light source 20 among the prisms provided on the first main surface 33. The prism row 38a composed of a plurality of conical continuous prisms 38 spans from the vicinity of the first side end surface 35 to the vicinity of the second side end surface 36 without including the long prism 37.

[0109] The prism array 38a disposed at the position closest to the light source 20 can appropriately scatter the light guide direction of the component that is not emitted to the outside of the light guide plate 30j after being reflected by the prism array 38a in the light guide plate 30j but continues to be guided in the light guide plate 30j. As a result, the light reflected by the long prism 37 is also scattered, so that the brightness unevenness of the irradiated surface, especially the rib-shaped brightness unevenness, can be reduced.

[0110] In addition, in order to scatter the above-mentioned light guiding direction, etc., in the light guide plate 30j, the control angle of the conical continuous prism 38 included in the above-mentioned prism column 38a can be different from the control angle of the conical continuous prism 38 not included in the above-mentioned prism column 38a.

[0111] [Arrangement example 8 of strip prisms]

[0112] Fig. 20 37 is a diagram showing an arrangement example 8 of the long prism 37. Fig. 20 In the light guide plate 30k shown, a prism row 38a composed of a plurality of conical continuous prisms 38 arranged along the X-axis direction and a prism row 37a composed of a plurality of elongated prisms 37 arranged along the X-axis direction are provided. The prism row 38a composed of a plurality of conical continuous prisms 38 spans from the vicinity of the first side end face 35 to the vicinity of the second side end face 36 without including the elongated prisms 37. The prism row 37a composed of a plurality of elongated prisms 37 spans from the vicinity of the first side end face 35 to the vicinity of the second side end face 36 without including the conical continuous prisms 38.

[0113] In the light guide plate 30k, the arrangement of the prism rows in the Y-axis direction is such that two or more prism rows are provided next to one prism row 38a (in Fig. 20 The light guide plate 30k has three rows of prism rows 37a and one prism row 38a next to it. The light guide plate 30k has a more beautiful light-emitting surface.

[0114] [Grid width]

[0115] When the strip prisms 37 are arranged in grid units, how to determine the width W of one grid in the Y-axis direction (in Fig.14 If the width W of the grid is made smaller, the processing of the long prism 37 becomes complicated, which takes time and cost, but the brightness unevenness of the irradiated surface becomes smaller. On the other hand, if the width W of the grid is made larger, the processing of the long prism 37 becomes easier, but the brightness unevenness becomes larger.

[0116] Here, the width W of the grid may be set as follows based on the number of reflections (hereinafter also referred to as the number of bounces) of light in the light guide plate 30e (or the light guide plate 30f, the light guide plate 30g). Fig.21 This is a diagram for explaining a method for determining the width W of a grid.

[0117] like Fig.21 As shown, the total light flux incident on the light guide plate 30e is diffused (in Fig.21propagates in a solid angle represented by a conical shape). Here, let the thickness of the light guide plate 30e be t. The greater the thickness t of the light guide plate 30e, the fewer the number of times the light in the light guide plate 30e bounces. The greater the thickness t of the light guide plate 30h, the longer the period of one bounce. That is, the greater the thickness t, the greater the width W of the grating that can be made.

[0118] Specifically, among the light guiding in the light guide plate 30e as incident light, the light guiding at the deepest angle guides at about 43° in the case of acrylic. If it is assumed that in this light, the light reflected by the first main surface 33 after entering the light guide plate 30e bounces n times and reaches the first main surface 33 again, then the light reflected by the second main surface 34 after entering the light guide plate 30e bounces n + 1 / 2 times and reaches the first main surface 33. The distance between the two beams of light in the Y-axis direction at this time is about t. Therefore, if W > t, the light incident at the deepest angle (43° in the case of acrylic) is reflected by different gratings in the nth and (n + 1)th bounces, so the effect of the grating can be fully obtained.

[0119] In addition, if the solid angle of 1 / 10 of the light flux incident on the light guide plate 30e is set to 2θ, it can be considered that if 90% of the light incident on the light guide plate 30e has a distance of 2t / tanθ in the Y-axis direction, then after being reflected by the first main surface 33, it bounces once on the second main surface 34 and reaches the first main surface 33 again. That is, when the light reflected by a certain grating of the first main surface 33 reaches the first main surface 33 again after being reflected by the second main surface 34, at least 10% of the light guiding in the light guide plate 30h is reflected by the adjacent grating. Therefore, the width of the grating in the Y direction is preferably W < 2t / tanθ.

[0120] Therefore, the width W of the grating in the Y-axis direction is set to satisfy, for example, the relational expression of t < W < 2t / tanθ. If the width W satisfies such a relational expression, a light guide plate 30e with the brightness unevenness of the irradiation surface within the allowable range can be realized with realistic processing time and cost.

[0121] [Modification Example]

[0122] The lighting device 10 may also include one of the light guide plates 30a to 30k instead of the light guide plate 30. In addition, for the light guide plate included in the lighting device 10, the arrangement of the long prism 37 obtained by arbitrarily combining two or more of the arrangement examples 1 to 8 can also be applied. For example, on the light guide plate included in the lighting device 10, the long prism 37 can be arranged in units of gratings as in the arrangement example 3, and the prism row 38 as in the arrangement example 7 can be provided as the boundary line of the grating along the X-axis direction.

[0123] The light source 20 is a so-called SMD type light emitting module, but the specific form of the light source 20 is not particularly limited. For example, as the light source 20, a COB (Chip On Board) type light emitting module may be used. Fig. 22 The diagrams show modified examples of such light sources.

[0124] In the light source 20 a , the plurality of light emitting elements 22 a are, for example, blue LED chips, and are arranged in a row along the longitudinal direction of the substrate 21 .

[0125] The plurality of light emitting elements are sealed in a linear shape by a sealing member 23 containing a phosphor. The base of the sealing member 23 is, for example, a silicone resin, but may also be an epoxy resin or a urea resin. The sealing member 23 may contain, for example, at least one of a yellow phosphor or a green phosphor. The sealing member 23 may also contain a red phosphor in addition to at least one of a yellow phosphor or a green phosphor.

[0126] Such a light source 20 a has a linear light emitting region that emits white light, and can reduce uneven brightness (graininess) on the irradiated surface compared to the light source 20 .

[0127] The light source used in the lighting device 10 may be a single-color LED or a light-emitting module that combines a plurality of single-color LEDs to produce mixed colors. The plurality of single-color LEDs may be, for example, three types of single-color LEDs of RGB, but other combinations are also possible.

[0128] [Effects, etc.]

[0129] As described above, the light guide plate 30 includes: a first main surface 33; side end surfaces (first side end surface 35, second side end surface 36), which are arranged at the end portion in the first direction along the first main surface 33; and a first end surface 31, which is arranged at the end portion in the second direction along the first main surface 33 and intersecting the first direction, for light emitted by the light source to be incident. A plurality of elongated prisms 37 having the first direction as the length direction are arranged on the first main surface 33. When the angle formed by the side surface of the elongated prism 37 on the light source 20 side and the first main surface 33 is assumed to be a control angle, the first prism group arranged along the first direction among the plurality of elongated prisms 37 includes elongated prisms 37 having different control angles. The first direction is the X-axis direction in the above embodiment, and the second direction is the Y-axis direction in the above embodiment.

[0130] Such a light guide plate 30 can reduce uneven brightness of the irradiated surface.

[0131] Furthermore, in the light guide plate 30 a , the second prism group arranged along the second direction among the plurality of elongated prisms 37 includes elongated prisms 37 having control angles different from each other.

[0132] Such a light guide plate 30a can improve the unevenness of light extraction from the entire light guide plate 30a and improve the light extraction efficiency. In addition, by making it easier to scatter the light path inside the light guide plate 30a, it is possible to reduce uneven brightness on the irradiation surface.

[0133] Furthermore, in the light guide plate 30 , the plurality of elongated prisms 37 are aligned in the first direction and the second direction.

[0134] Such a light guide plate 30 can improve the aesthetics of the light emitting surface of the light guide plate 30 .

[0135] Furthermore, in the light guide plate 30 b , a plurality of elongated prisms 37 are arranged in a staggered pattern.

[0136] In such a light guide plate 30 b , the possibility that the light emitted from the light source 20 is reflected by the elongated prisms 37 increases, thereby improving the light extraction efficiency.

[0137] In addition, in the light guide plate 30 e , a plurality of grids are provided on the first main surface 33 . The plurality of grids are regions where the elongated prisms 37 having the same control angle are uniformly arranged.

[0138] Such a light guide plate 30e can be easily optically designed by a designer. In addition, since a plurality of elongated prisms 37 belonging to one grid can be formed together in one process, the time required for processing can be shortened.

[0139] In addition, in the light guide plate 30e, the control angle of the elongated prism 37 belonging to the central grid among the three grids arranged along the first direction is larger than the control angle of the elongated prism 37 belonging to the other two grids among the three grids, or smaller than the control angle of the elongated prism 37 belonging to the other two grids among the three grids.

[0140] Such a light guide plate 30 e can improve the light extraction efficiency of light obliquely guided from the light source 20 toward the second end surface 32 .

[0141] In addition, in the light guide plate 30e, the control angle of the elongated prism 37 belonging to the central grid among the three grids arranged along the second direction is larger than the control angle of the elongated prism 37 belonging to the other two grids among the three grids, or smaller than the control angle of the elongated prism 37 belonging to the other two grids among the three grids.

[0142] By using such a light guide plate 30e, it is possible to obtain the effects of reducing uneven brightness of the irradiated surface, improving the accuracy of the optical design, and making light extraction uniform. In addition, since the style of the long prism 37 looks like a pattern, the pattern attracts the eye, so the sense of incongruity in appearance caused by processing deviations of the long prism 37 can be reduced.

[0143] In addition, in the light guide plate 30e, if the thickness of the light guide plate 30e is set to t and the solid angle corresponding to 1 / 10 of the luminous flux incident on the light guide plate 30e is set to 2θ, the width W in the second direction of the grating satisfies the relational expression of t < W < 2t / tanθ.

[0144] In this way, if the width W satisfies such a relational expression, it is possible to realize the light guide plate 30e in which the brightness unevenness of the irradiation surface is within the allowable range with realistic processing time and cost.

[0145] In addition, in the light guide plate 30f, the arrangement of the long prisms 37 with the same control angle is symmetric with respect to the second imaginary line L2 that bisects the first main surface 33 along the second direction.

[0146] Such a light guide plate 30f can realize a brightness distribution symmetric with respect to the first direction and can reduce the brightness unevenness in the first direction of the irradiation surface.

[0147] In addition, in the light guide plate 30g, when the first main surface 33 is divided into a first region R1 on the light source 20 side and a second region R2 by the first imaginary line L1 along the first direction, the average value of the control angles of the long prisms 37 provided in the first region R1 is smaller than the average value of the control angles of the long prisms 37 provided in the second region R2.

[0148] In this way, the light guide plate 30g can effectively extract wide light. In addition, the light guide plate 30g can increase the light extraction amount of the entire light guide plate 30g.

[0149] In addition, in the light guide plate 30h, a conical continuous prism 38 is provided on the first main surface 33, and the conical continuous prism 38 is formed by connecting conical prisms in the first direction by a length corresponding to the length direction of the long prism 37.

[0150] Such a light guide plate 30h can reduce the brightness unevenness of the irradiation surface by realizing a brightness distribution that cannot be achieved only by the long prism 37.

[0151] In addition, in the light guide plate 30j, a plurality of conical continuous prisms 38 arranged along the first direction are located on the light source 20 side among the prisms provided on the first main surface 33.

[0152] Such a light guide plate 30j can reduce the brightness unevenness of the irradiation surface, particularly reduce the streak-like brightness unevenness.

[0153] In addition, in the light guide plate 30, the difference between the control angles of the long prisms 37 with different control angles is 1° or more and 55° or less.

[0154] Such a light guide plate 30 can reduce the brightness unevenness of the irradiation surface by means of a variety of long prisms 37 with a difference between the control angles of 1° or more and 55° or less.

[0155] Furthermore, the lighting device 10 includes a light guide plate 30 and a light source 20 .

[0156] Such a lighting device 10 can reduce uneven brightness of the irradiated surface.

[0157] Furthermore, for example, the light source 20 a has a linear light emitting region along the first direction.

[0158] The lighting device 10 including such a light source 20 a can reduce uneven brightness (graininess) on the irradiated surface.

[0159] (Other embodiments)

[0160] As mentioned above, although embodiment was described, this invention is not limited to the said embodiment.

[0161] In the above embodiment, a wall lamp is exemplified as a lighting device, but the present invention can also be implemented as other lighting devices. For example, the present invention can be implemented as a pole lamp installed outdoors, or as a foot lamp installed under the wall of a house or the like to illuminate the user's feet. The present invention can also be implemented as a lighting device such as a table lamp. The present invention can also be implemented as other lighting devices using a light guide plate.

[0162] Furthermore, in the above embodiment, a light emitting module using LEDs is used as a light source. However, a light emitting module including solid light emitting elements other than LEDs such as organic EL (Electro-Luminescence) elements or inorganic EL elements may be used as a light source.

[0163] Furthermore, in the above-described embodiment, a light guide plate having a rectangular shape in plan view is exemplified as the light guide plate, but light guide plates having other shapes may be used in the lighting device.

[0164] In addition, various modifications that can be conceived by those skilled in the art to the embodiments, or embodiments implemented by arbitrarily combining the components and functions of the embodiments without departing from the gist of the present invention are also included in the present invention.

Claims

1. A light guide plate, characterized in that: It has: A main surface; A side end face, provided at an end in a first direction along the main surface; and An end face, provided at an end in a second direction along the main surface and intersecting the first direction, for light emitted by a light source to be incident; A plurality of long prisms with the first direction as the length direction are provided on the main surface; When the angle formed by the side surface of the long prism on the light source side and the main surface is a control angle, among the plurality of long prisms, in a first prism group arranged along the first direction, the long prisms with different control angles are included; A plurality of grids are provided on the main surface, and the plurality of grids are regions where the long prisms with the same control angle are uniformly arranged; If the thickness of the light guide plate is set as t, and the angle obtained by observing from the side the apex angle of a conical shape representing the diffusion of the light flux incident on the light guide plate and having 1 / 10 of the light flux is set as 2θ, then the width W in the second direction of the grid satisfies the relational expression of t < W < 2t / tanθ.

2. The light guide plate according to claim 1, characterized in that: Among the plurality of long prisms, in a second prism group arranged along the second direction, the long prisms with different control angles are included.

3. The light guide plate according to claim 1, characterized in that: The plurality of long prisms are aligned in the first direction and the second direction respectively.

4. The light guide plate according to claim 1, characterized in that: The plurality of long prisms are arranged in a staggered manner.

5. The light guide plate according to claim 1, characterized in that: The control angle of the long prism belonging to the central grid among the three grids arranged along the first direction is larger than the control angles of the long prisms belonging to the other two grids among the three grids, or smaller than the control angles of the long prisms belonging to the other two grids among the three grids.

6. The light guide plate according to claim 1, characterized in that: The control angle of the long prism belonging to the central grid among the three grids arranged along the second direction is larger than the control angles of the long prisms belonging to the other two grids among the three grids, or smaller than the control angles of the long prisms belonging to the other two grids among the three grids.

7. The light guide plate according to claim 1, characterized in that: The arrangement of the long prisms with the same control angle is symmetric about a second imaginary line that bisects the main surface along the second direction.

8. The light guide plate according to claim 1, characterized in that: When the main surface is divided into a first region on the light source side and a second region by a first imaginary line along the first direction, the average value of the control angles of the long prisms provided in the first region is smaller than the average value of the control angles of the long prisms provided in the second region.

9. The light guide plate according to claim 1, characterized in that: A conical continuous prism is provided on the main surface. The conical continuous prism is formed by connecting conical prisms in the first direction by a length corresponding to the length direction of the long prism.

10. The light guide plate according to claim 9, wherein: The plurality of conical continuous prisms arranged along the first direction are located closest to the light source among the prisms provided on the main surface.

11. The light guide plate according to any one of claims 1 to 10, wherein: The difference in control angles of the elongated prisms having different control angles is greater than or equal to 1° and less than or equal to 55°.

12. A lighting device, characterized in that: have: The light guide plate according to any one of claims 1 to 11; and The above light source.

13. The lighting device according to claim 12, characterized in that: The light source has a linear light emitting area along the first direction.

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