CN115144949A - Light guide plate and lighting device - Google Patents

Abstract

A light guide plate (30) is provided with: a 1 st main surface (33); a side end surface provided at an end in the 1 st direction along the 1 st main surface (33); and a 1 st end surface (31) provided at an end portion in a 2 nd direction along the 1 st main surface (33) and intersecting the 1 st direction, and on which light emitted from the light source is incident. A plurality of elongated prisms (37) are provided on the 1 st main surface (33) with the 1 st direction as the longitudinal direction. When the angle formed by the side surface of the long prism (37) on the light source (20) side and the main surface is a control angle, the 1 st prism group arranged along the 1 st direction in the plurality of long prisms (37) includes long prisms (37) having different control angles.

Description

Light guide plate and lighting device

technical field

The present invention relates to a light guide plate and a lighting device including the light guide plate.

Background technique

Various devices using a light guide plate have been proposed. For example, Patent Document 1 discloses a light guide plate capable of switching the display style according to the light source lit among the plurality of light sources even when a plurality of light sources are arranged only on one end side of the light guide plate, and a light guide plate provided with the light guide plate. Light board game console.

prior art literature

Patent Literature

Patent Document 1: Japanese Patent Laid-Open No. 2016-122162

SUMMARY OF THE INVENTION

The problem to be solved by the invention

The present invention provides a light guide plate and an illuminating device capable of reducing uneven brightness of an irradiated surface.

means to solve the problem

A light guide plate according to an aspect of the present invention includes: a main surface; a side end surface provided at an end portion in a first direction along the main surface; and an end surface provided along the main surface and crossing the first direction The end portion in the second direction of the light source is incident for the light emitted by the light source; a plurality of long prisms are arranged on the main surface with the first direction as the longitudinal direction; When the angle formed by the main surface is a control angle, the first prism group arranged in the first direction among the plurality of elongated prisms includes the elongated prisms whose control angles are different from each other.

An illuminating device according to an aspect of the present invention includes the light guide plate described above and the light source described above.

Invention effect

The light guide plate and the lighting device according to one aspect of the present invention can reduce unevenness in luminance on the irradiation surface.

Description of drawings

FIG. 1 is an external view of a lighting device according to an embodiment.

FIG. 2 is a cross-sectional view of the lighting device according to the embodiment.

3 is a diagram showing the arrangement of a light source and a light guide plate of the lighting device according to the embodiment.

FIG. 4 is a diagram showing the arrangement of the elongated prisms in the light guide plate according to the comparative example.

FIG. 5 is a diagram showing the position of the elongated prism and the schematic optical path of the light emitted from the light source.

FIG. 6 is a diagram showing a simulation result of a light distribution characteristic of light reflected by a long prism.

FIG. 7 is a diagram showing four types of luminance distributions on the irradiated surface.

FIG. 8 is a diagram showing the luminance distribution in the Y-axis direction of the irradiation surface facing the light guide plate according to the comparative example.

FIG. 9 is a diagram showing the luminance distribution in the Y-axis direction of the irradiation surface facing the light guide plate according to the embodiment.

FIG. 10 is a diagram showing an arrangement example 1 of the elongated prisms.

FIG. 11 is a diagram showing an arrangement example 2 of the elongated prisms.

FIG. 12 is a first view showing arrangement example 3 of the elongated prisms.

FIG. 13 is a second view showing arrangement example 3 of the elongated prisms.

FIG. 14 is a third diagram showing an arrangement example 3 of the elongated prisms.

FIG. 15 is a diagram showing an arrangement example 4 of the elongated prisms.

FIG. 16 is a diagram showing arrangement example 5 of the elongated prisms.

FIG. 17 is a diagram showing arrangement example 6 of the elongated prisms.

FIG. 18 is a diagram showing a modification of the arrangement example 6 of the elongated prisms.

FIG. 19 is a diagram showing arrangement example 7 of the elongated prisms.

FIG. 20 is a diagram showing an arrangement example 8 of the elongated prisms.

FIG. 21 is a diagram for explaining a method of determining the width of a grid.

FIG. 22 is a diagram showing a modification of the light source.

Description of reference numerals

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 main face; 34 second main face; 35 first side end face; 36 second side end face; 37 long prism; 37a, 38a prism row; 38 conical continuous prism; 40 transparent cover; 50 reflector; 60 box body; 70 holding part; 80 end face cover; 91 wall surface; 92 ceiling noodle.

Detailed ways

Hereinafter, embodiments will be described with reference to the drawings. The embodiments described below are all inclusive or specific examples. Numerical values, shapes, materials, components, arrangements of components, connection forms, and the like shown in the following embodiments are examples, and are not intended to limit the present invention. In addition, among the components of the following embodiments, components not described in the independent claims representing the highest-level concept of the present invention will be described as arbitrary components.

In addition, each figure is a schematic diagram, and is not necessarily shown strictly. In addition, in each figure, the same code|symbol is attached|subjected to the substantially same structure, and the overlapping description may be abbreviate|omitted or simplified. In addition, in the following embodiment, the expression which is the same does not mean the same in a strict sense, but means substantially the same. Substantially the same, for example, means the same within a range including manufacturing errors, dimensional tolerances, and the like.

In addition, in the following embodiment, a coordinate axis may be shown in the drawing for description. The Z-axis direction will be described as the thickness direction of the light guide plate. 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, a plan view refers to viewing from the Z-axis direction.

(Embodiment)

[Lighting device]

Hereinafter, the lighting device according to the embodiment will be described. FIG. 1 is an external view of a lighting device according to an embodiment.

As shown in FIG. 1 , the lighting device 10 according to the embodiment is a bracket light. In FIG. 1 , the lighting device 10 is installed on the wall surface 91 to irradiate the ceiling surface 92 with light, but may be installed on the wall surface 91 and irradiated with light to the ground surface.

Next, the internal structure of such a lighting device 10 will be described. FIG. 2 is a cross-sectional view of the lighting device 10 . As shown in FIG. 2 , the lighting device 10 includes a light source 20 , a light guide plate 30 , a light-transmitting cover 40 , a reflector 50 , and a case 60 .

First, the light source 20 and the light guide plate 30 will be described with reference to FIGS. 2 and 3 . FIG. 3 is a diagram showing the arrangement of the light source 20 and the light guide plate 30 . FIG. 3( a ) is a view of the light source 20 and the light guide plate 30 viewed from the X-axis direction, FIG. 3( b ) is a view of the light source 20 and the light guide plate 30 viewed from the Z-axis direction, and FIG. 3( c ) is viewed from the The light source 20 and the light guide plate 30 are viewed in the Y-axis direction.

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 has a substrate 21 and a light emitting element 22 .

The substrate 21 is an elongated rectangular substrate 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 in parallel with the first end surface 31 of the light guide plate 30 . In addition, the shape of the substrate 21 is not particularly limited.

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

The main surface of the substrate 21 on which the plurality of light-emitting elements 22 are mounted, ie, the mounting surface, 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 .

The light emitting element 22 is a surface mount type (Surface Mount Device: 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 resin-molded cavity, and a phosphor-containing resin is sealed in the cavity. The light emitting element 22 emits white light of, for example, sunlight color to incandescent lamp color (color temperature 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 .

In addition, the light source 20 is electrically connected to a power supply circuit (not shown) in the housing 60 through a cable (not shown), and emits light by the power supplied from the power supply circuit.

The light guide plate 30 is a flat optical member having a rectangular shape when viewed from the Z-axis direction, in other words, a light guide. The light guide plate 30 is a transparent member, but only a member having translucency may be used. The light guide plate 30 is formed of, for example, acrylic resin, but may be formed of polycarbonate resin, glass, or the like.

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 .

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 into which the light emitted by the light source 20 enters, and is, for example, a flat surface. The second end surface 32 is an end surface on the opposite side of the first end surface 31 (ie, the end surface facing away from the first end surface 31 ) of the end in the Y-axis direction of the light guide plate 30 , and is, for example, a flat surface.

The first main surface 33 is a main surface provided with a reflection structure that reflects the light incident on the first end surface 31 to the second main surface 34 side. On the first main surface 33, a plurality of fine elongated prisms 37 are provided as a reflection structure.

The elongated prism 37 is a concave portion provided on the first principal surface 33, but may be a convex portion. In the drawing, the elongated prism 37 is shown as being large for the sake of explanation, but it is actually small. The length of the elongated prism 37 is, for example, about 4 mm. The elongated prism 37 has a longitudinal direction in the X-axis direction. In other words, the X-axis direction is the first direction along the first main surface 33 , and is a direction perpendicular to the second direction (Y-axis direction) in which the first end surfaces 31 and the second end surfaces 32 are arranged.

As shown in FIG. 3( a ), the elongated prism 37 is an elongated groove having a substantially V-shaped cross section. When an angle θ1 formed by 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 . In FIG. 3( b ), the elongated prisms 37 of different colors represent prisms of different control angles. The same applies to the subsequent figures.

Although three types of elongated prisms 37 with different control angles are shown in the figure, in reality, 10 to 20 types of elongated prisms 37 with different control angles are provided on the first main surface 33 . The difference between the control angles of the elongated prisms 37 having different control angles is, for example, 1° or more and 55° or less. Specifically, it is about 1° in a combination with a small difference in the control angles, and exceeds 50° in a combination with a large difference in the control angles. The cross-sectional shape of the elongated prism 37 may be a symmetrical shape (that is, θ1=θ2 in FIG. 3( a )), but the light extraction efficiency can be improved by θ1<θ2 . The elongated prisms 37 are formed on the first main surface 33 by thermal processing such as laser processing, for example.

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

The second main surface 34 is a main surface located on the opposite side of the first main surface 33 (ie, the main surface facing away from the first main surface 33 ). The second main surface 34 is a flat surface. The reflection structure is not provided on the second main surface 34 , but a plurality of elongated prisms 37 may be provided as the reflection structure similarly to the first main surface 33 .

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

Next, the translucent 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 casing of the lighting device 10 and functions as an extraction port for light emitted from the light guide plate 30 . The base of the translucent cover 40 is formed of, for example, acrylic resin, but may be formed of polycarbonate resin, glass, or the like.

Further, the light-transmitting cover 40 is a cover that transmits light emitted from the light guide plate 30 . The translucent cover 40 may have a function of diffusing the light emitted from the light guide plate 30 (light diffusing function). For example, the light-transmitting cover 40 may have a light-diffusing function by including a light-diffusing material such as silica as the base.

Next, the reflector 50 will be described. The reflector 50 is a flat plate-shaped member having a rectangular shape in plan view. The reflection plate 50 is arranged so that the reflection 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. In addition, the reflector 50 may be formed of a white resin material, a metal film-added resin material, a white-coated resin material, a white-coated metal material, or the like. According to the reflector 50 , the lighting device 10 can efficiently emit light only to one side (the Z-axis-side in the example of FIG. 10 ). In addition, the plan view shape of the reflection plate 50 is not limited to a rectangle, and may be other shapes.

Next, the case 60 will be described. The box 60 holds the light source unit including the light source 20 , the light guide plate 30 and the reflection plate 50 , and the light transmission cover 40 . The light source unit includes, in addition to the light source 20 , the light guide plate 30 and the reflection plate 50 , a holding portion 70 and an end cover 80 . The light source 20 and the light guide plate 30 are integrally held by the holding portion 70 , and the reflection plate 50 is pushed by the end cover 80 . pressed on the light guide plate 30 . In addition, the case 60 constitutes the outer profile of the lighting device 10 . The case 60 is formed of, for example, a metal material, but may be formed of a resin material.

[Configuration of long prism]

The illumination device 10 reduces unevenness in luminance on the irradiation surface (in the example of FIG. 1 , the ceiling surface 92 ) to which light is irradiated by the illumination device 10 by disposing the elongated prisms 37 of the light guide plate 30 . Hereinafter, the light guide plate 30 included in the illuminating device 10 is compared with the light guide plate of the comparative example, and the reason why the uneven brightness is reduced will be described. FIG. 4 is a diagram showing the arrangement of the elongated prisms 37 of the light guide plate according to the comparative example.

As shown in (b) of FIG. 3 , in the light guide plate 30 , among the plurality of elongated prisms 37 , the first prism group arranged in the X-axis direction includes elongated prisms 37 with mutually different control angles. In the example of FIG. 3( b ), three types of elongated prisms 37 having different control angles are included in the first prism group composed of five elongated prisms 37 arranged in the X-axis direction.

On the other hand, as shown in FIG. 4 , in the light guide plate 30z according to the comparative example, among the plurality of elongated prisms 37 , the first prism group arranged in the X-axis direction includes only prisms having the same control angle. The elongated prisms 37 include elongated prisms 37 whose control angles are different from each other in the second prism group arranged in the Y-axis direction.

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

As shown in FIG. 5 , light having a larger exit angle with respect to the optical axis of the light source 20 is reflected by the group of elongated prisms 37 located near the light source 20 , and is less likely to reach the group of elongated prisms 37 far from the light source 20 . As a result, as shown in FIG. 6 , the closer the group of elongated prisms 37 to the light source 20 is, the greater the amount of light reflected. In addition, the position of the peak of the light distribution characteristic also changes. In FIG. 6 , the peak of the light distribution characteristic of the group of elongated prisms 37 provided at the position (1) is located in the vicinity of 220°, but is provided at the position (5) The peak value of the light distribution characteristic of the group of elongated prisms 37 is located in the vicinity of 225°.

In view of the results of such simulations, it is assumed that the luminance distribution of the irradiation surface is as shown in FIG. 7 according to the position of the elongated prism 37 and the control angle of the elongated prism 37 . FIG. 7 is a diagram showing four types of luminance distributions (NA, NB, FA, and FB) on the irradiated surface. In FIG. 7 , the vertical axis represents the luminance, and the horizontal axis represents the position of the irradiation surface in the Y-axis direction.

NA is the luminance distribution realized by the long prism 37 whose control angle is A and which is arranged at a position N closer to the light source 20 . NB is the luminance distribution realized by the long prism 37 provided at the position N with the control angle B (in the example of FIG. 7 , B<A). In addition, FA is the luminance distribution realized by the long prism 37 set at the position F farther from the light source 20 with the control angle A, and FB is realized by the long prism 37 set at the position F with the control angle B brightness distribution. In addition, the position N and the position F are shown by the dotted line in FIG.3(b) and FIG.4.

As shown in FIG. 4 , in the light guide plate 30z of the comparative example, only the long prisms 37 having the same control angle are included in the first prism group arranged in the X-axis direction. For the light guide plate 30z of the comparative example, only one type of long prism 37 (for example, the long prism 37 controlling the angle A) is provided at the position N that is relatively close to the light source 20 , and the position N is farther from the light source 20 . At the position F, only one type of long prism 37 (for example, the long prism 37 for the control angle B) is provided.

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

On the other hand, as shown in (b) of FIG. 3 , the light guide plate 30 includes elongated prisms 37 whose control angles are different from each other in the first prism group arranged in the X-axis direction. Specifically, for the light guide plate 30, a plurality of long prisms 37 (for example, the long prism 37 with the control angle A and the long prism 37 with the control angle B) are provided at the position N close to the light source 20 ). The light guide plate 30 is also provided with various long prisms 37 (eg, the long prism 37 with the control angle A and the long prism 37 with the control angle B) at the position F far from the light source 20 . Such an arrangement of the elongated prisms 37 can be said to be less susceptible to 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 FIG. 6 .

Therefore, the luminance distribution in the Y-axis direction of the irradiation surface facing the light guide plate 30 realized by the long prism 37 provided at the position N and the long prism 37 provided at the position F is as shown in FIG. 9 with As indicated by the dotted line, it has a shape obtained by adding NA, NB, FA, and FB. FIG. 9 is a diagram showing the luminance distribution in the Y-axis direction of the irradiation surface facing the light guide plate 30 .

The luminance distribution shown in FIG. 9 has less unevenness than the luminance distribution shown in FIG. 8 . That is, the light guide plate 30 can reduce the unevenness of luminance on the irradiation surface as compared with the light guide plate 30z.

[Example 1 of arrangement of elongated prisms]

Hereinafter, another example of arrangement of the elongated prisms 37 will be described. FIG. 10 is a diagram showing an arrangement example 1 of the elongated prisms 37 .

In the light guide plate 30 shown in FIG. 3 , the first prism group arranged along the first direction includes elongated prisms 37 with mutually different control angles, and the second prism group arranged along the second direction includes prisms 37 . The control angles of the elongated prisms 37 are unified. On the other hand, in the light guide plate 30a shown in FIG. 10 , not only the first prism group includes the elongated prisms 37 having mutually different control angles, but also the second prism group includes the elongated prisms 37 having mutually different control angles .

In the case where only the long prisms 37 with high light extraction efficiency (for example, prisms with large control angles) are included in the second prism group arranged in the second direction, in the light guide plate 30 arranged in the second direction The elongated prism 37 extracts light from the light source 20 side, and the light extraction from the elongated prism 37 on the exit end face (second end face 32 ) side decreases, and the prism drawing area of the light guide plate 30 may not be effectively used. On the other hand, when only the long prisms 37 with low light extraction efficiency (for example, prisms with small control angles) are included in the second prism group arranged in the second direction, there are cases where the prisms along the light guide plate 30 In the case where the light between the prisms arranged in the second direction is not completely extracted, the light guided reaches the second end surface 32 and the amount of light extracted from the second main surface 34 is reduced. When there is unevenness in light extraction from the light guide plate 30 as described above, there is a possibility that the light extraction efficiency of the entire light guide plate 30 may decrease.

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

Further, light incident on the elongated prism 37 provided at a position away from the light source 20 includes light whose optical path is disturbed by the elongated prism 37 located on the light source 20 side than the elongated prism 37 . Therefore, as in the light guide plate 30a, not only the first prism group includes the elongated prisms 37 with mutually different control angles, but also the second prism group includes the elongated prisms 37 with mutually different control angles, thereby facilitating the optical path. Scattered. When the optical path is scattered, the way of taking out light changes, and the width of the luminance distribution of the light taken out from the various elongated prisms 37 can be widened. When the luminance distributions of light having a wider width are combined together, the luminance distributions are smoothly connected, and the luminance unevenness of the irradiated surface is reduced.

[Example 2 of arrangement of elongated prisms]

FIG. 11 is a diagram showing an arrangement example 2 of the elongated prisms 37 . In the light guide plate 30 ( FIG. 3 ) and the light guide plate 30 a ( FIG. 10 ), the plurality of elongated prisms 37 are arranged in a matrix, but in the light guide plate 30 b shown in FIG. 11 , the plurality of elongated prisms 37 are arranged For the staggered shape (staggered shape, houndstooth shape).

In the matrix-like arrangement, a linear region (for example, region L in FIG. 10 ) is formed from the first end face 31 to the second end face 32 in which the elongated prisms 37 are not provided. On the other hand, in the light guide plate 30 b , since such a linear region is not provided, the light emitted from the light source 20 is prevented from reaching the second end face 32 without being reflected by the elongated prism 37 . In other words, the possibility that the light emitted from the light source 20 is reflected by the elongated prism 37 is increased, and the light extraction efficiency can be improved.

In addition, as shown in FIG. 11 , in a staggered arrangement, elongated prisms shorter than normal elongated prisms 37 may be provided at the ends in the X-axis direction. In addition, in any of the arrangements of FIGS. 3 , 10 , and 11 , it can be said that the plurality of elongated prisms 37 are aligned in the X-axis direction and the Y-axis direction, respectively. Thereby, the appearance of the light-emitting surface of the light guide plate 30 (or the light guide plate 30a, the light guide plate 30b) is improved.

[Example 3 of arrangement of elongated prisms]

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

In the light guide plate 30c, the light guide plate 30d, and the light guide plate 30e shown in FIGS. 12 to 14, the regions demarcated by the dotted lines are grids, respectively. In one grid, a plurality of elongated 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, respectively.

The total number of grids, the size of the grids, and the shape of the grids are not particularly limited. Like the light guide plate 30c shown in FIG. 12 and the light guide plate 30d shown in FIG. 13 , the plurality of grids may include grids having different shapes and sizes. Like the light guide plate 30e shown in FIG. 14 , the shapes and sizes of the plurality of grids may be substantially uniform.

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

In addition, if the magnitude relationship of the control angle is changed at small intervals in grid units in the X-axis direction, the light extraction efficiency of light guided obliquely from the light source 20 toward the second end face 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 continuously arranged in the X-axis direction to be smaller than the control angle of the elongated prism belonging to the other two grids among the three grids The control angle of 37 is larger or smaller than the control angle of the elongated prisms 37 belonging to the other two gratings among the three gratings, so that the light extraction efficiency can be improved.

In addition, by changing the magnitude relationship of the control angles at small intervals in units of grids in the Y-axis direction, effects such as reducing unevenness in luminance on the irradiated surface, improving the accuracy of optical design, and uniformizing light extraction can be obtained. . In addition, since the pattern of the elongated prisms 37 looks like a pattern, and the pattern attracts attention, it is possible to reduce the appearance of the elongated prisms 37 due to variations in processing or the like. That is, by setting the control angle of the elongated prism 37 belonging to the central grid among the three grids continuously arranged in the Y-axis direction to be smaller than the control angle of the elongated prism belonging to the other two grids among the three grids If the control angle of 37 is larger or smaller than the control angle of the elongated prisms 37 belonging to the other two gratings among the three gratings, the above-mentioned effects can be obtained.

[Example 4 of arrangement of elongated prisms]

FIG. 15 is a diagram showing an arrangement example 4 of the elongated prisms 37 . In FIG. 15, the long prisms 37 of different colors, the darker the color, the larger the control angle. In the light guide plate 30f shown in FIG. 15, the arrangement of the elongated prisms 37 having the same control angle is bilaterally symmetrical. For example, in FIG. 15 , the arrangement of the black elongated prisms 37 is symmetrical with respect to the second imaginary line L2. The arrangement of the dark gray elongated prisms 37 , the arrangement of the light gray elongated prisms 37 , and the arrangement of the white elongated prisms 37 are also symmetrical with respect to the second imaginary line L2 . In addition, the second imaginary straight line L2 is an imaginary straight line that bisects the first main surface 33 in the Y-axis direction.

Such a light guide plate 30f can realize a symmetrical light distribution in the X-axis direction (left-right direction), and can reduce luminance unevenness in the X-axis direction of the irradiation surface.

[Example 5 of arrangement of elongated prisms]

FIG. 16 is a diagram showing an arrangement example 5 of the elongated prisms 37 . In FIG. 16, the long prisms 37 of different colors, the darker the color, the larger the control angle. In the light guide plate 30g shown in FIG. 16 , when the first main surface 33 is divided into a first region R1 and a second region R2 on the light source 20 side by a first imaginary straight line L1 along the X-axis direction, it is provided in the The average value of the control angles of the elongated prisms 37 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 angle of the elongated prism 37 becomes larger as the distance from the light source 20 increases on average.

In this way, by arranging the long prism 37 with a small control angle for generating wide light on the side of the light source 20 with high light extraction efficiency, the wide light can be extracted efficiently. By arranging the long prism 37 with a large control angle on the second end face 32 side, the light incident on the long prism 37 at a shallow angle can be efficiently extracted, and the light extraction of the entire light guide plate 30g can be increased. quantity.

[Example 6 of arrangement of elongated prisms]

FIG. 17 is a diagram showing an arrangement example 6 of the elongated prisms 37 . In the light guide plate 30h shown in FIG. 17 , not only the elongated prisms 37 but also the conical continuous prisms 38 are provided. The conical continuous prism 38 is a prism formed by connecting conical prisms (conical concave portions or convex portions) in the X-axis direction by a length corresponding to the longitudinal direction of the elongated prisms 37 . The number of conical prisms included in one conical continuous prism 38 is not particularly limited.

In the light guide plate 30h, in the staggered arrangement like the light guide plate 30b, a part of the elongated prisms 37 is replaced with a conical continuous prism 38. However, a matrix such as the light guide plate 30 or the light guide plate 30a may be used. In the shape of the configuration, a part of the elongated prisms 37 is replaced by a continuous cone-shaped prism 38 . The position where the conical continuous prism 38 is arranged may be appropriately arranged empirically or experimentally. FIG. 18 is a diagram showing a modification of the arrangement example 6 of the elongated prisms. For example, like the light guide plate 30i shown in FIG. 18 , all the elongated prisms 37 existing in the grid may be replaced with conical continuous prisms 38 .

The light distribution characteristic of the conical continuous prism 38 is greatly different from that of the elongated prism 37 . By providing the conical continuous prism 38 having a light distribution characteristic greatly different from that of the elongated prism 37 in this way, the luminance distribution of the irradiation surface that cannot be realized by the elongated prism 37 alone can be realized. As a result, unevenness in luminance on the irradiated surface is reduced.

In addition, although one type of conical continuous prism 38 is provided on the light guide plate 30h or the first main surface 33 of the light guide plate 30i, for example, a plurality of types of conical continuous prisms 38 with different control angles may be provided.

[Example 7 of arrangement of elongated prisms]

FIG. 19 is a diagram showing an arrangement example 7 of the elongated prisms 37 . In the light guide plate 30j shown in FIG. 19 , a prism row 38a composed of a plurality of conical continuous prisms 38 arranged in the X-axis direction is provided on the most side of the light source 20 among the prisms provided on the first main surface 33 Position (Y-axis direction). In other words, among the prisms provided on the first principal surface 33 , the plurality of conical continuous prisms 38 arranged in the X-axis direction are located closest to the light source 20 . The prism row 38 a 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 , excluding the elongated prisms 37 .

The prism array 38a provided at the position closest to the light source 20 in this way can guide the components that continue to guide light in the light guide plate 30j without being emitted to the outside of the light guide plate 30j after being reflected by the prism array 38a in the light guide plate 30j. The light direction is moderately scattered. As a result, the light reflected by the elongated prism 37 is also scattered, so that the unevenness of brightness on the irradiation surface, especially the unevenness of brightness in the form of streaks, can be reduced.

In addition, in the light guide plate 30j, the control angle of the conical continuous prisms 38 included in the above-mentioned prism row 38a may be adjusted to those of the cones not included in the above-mentioned prism row 38a for the purpose of dispersing the above-mentioned light guide direction, etc. The control angles of the continuous prisms 38 are different.

[Example 8 of arrangement of elongated prisms]

FIG. 20 is a diagram showing an arrangement example 8 of the elongated prisms 37 . The light guide plate 30k shown in FIG. 20 is provided with a prism row 38a composed of a plurality of conical continuous prisms 38 aligned in the X-axis direction, and a prism row 38a composed of a plurality of elongated prisms 37 aligned in the X-axis direction Prism row 37a. The prism row 38 a 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 , excluding the elongated prisms 37 . The prism row 37 a including the 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 , excluding the conical continuous prisms 38 .

In the light guide plate 30k, the prism rows in the Y-axis direction are arranged such that two or more (three rows in FIG. 20) prism rows 37a are provided beside one prism row 38a, and one prism row 37a is provided beside the prism row 38a. The pattern of prism row 38a is repeated. The appearance of the light-emitting surface of such a light guide plate 30k is improved.

[width of grid]

When the elongated prisms 37 are arranged in grid units, there is room for study on how to determine the width W (shown in FIG. 14 ) in the Y-axis direction of one grid. If the width W of the grid is made small, the processing of the elongated prism 37 becomes complicated, and the processing takes time and cost, but the unevenness of the luminance on the irradiation surface is reduced. On the other hand, if the width W of the grid is made larger, the processing of the elongated prisms 37 becomes easy, but the unevenness in luminance becomes relatively large.

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 and the light guide plate 30g). FIG. 21 is a diagram for explaining a method of determining the width W of the grid.

As shown in FIG. 21 , the entire luminous flux incident on the light guide plate 30e propagates with diffusion (solid angle indicated by a conical shape in FIG. 21 ). Here, the thickness of the light guide plate 30e is assumed to be t, and the larger the thickness t of the light guide plate 30e, the smaller the number of times the light in the light guide plate 30e bounces. The larger the thickness t of the light guide plate 30h, the longer the period of one rebound. That is, the larger the thickness t, the larger the width W of the grid can be.

Specifically, among the lights guided in the light guide plate 30 e as incident light, the light guided at the deepest angle is guided at about 43° in the case of acryl. Assuming that the light reflected by the first main surface 33 after being incident on the light guide plate 30e bounces n times and reaches the first main surface 33 again, the light is reflected by the second main surface 34 after being incident on the light guide plate 30e. The light bounces n+1/2 times and reaches the first main surface 33 . The distance in the Y-axis direction of the two beams at this time is about t. Therefore, if W>t, light incident at the deepest angle (43° in the case of acryl) is reflected on different grids in the n-th and n+1-th bounces, so it is possible to obtain sufficient Grid effect.

In addition, if the solid angle at which the luminous flux incident on the light guide plate 30e is 1/10 is 2θ, it is conceivable 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 on 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 grid of the first main surface 33 is reflected by the second main surface 34 and reaches the first main surface 33 again, at least 10% of the light guided in the light guide plate 30h is caused by the adjacent light guide plate 30h. Grid reflection. Therefore, the width of the grid in the Y direction is preferably W<2t/tanθ.

Therefore, the width W of the grid in the Y-axis direction is set to satisfy the relational expression of t<W<2t/tanθ, for example. If the width W satisfies such a relational expression, the light guide plate 30e in which the luminance unevenness of the irradiated surface is an allowable range can be realized with realistic processing time and cost.

[Variation]

The lighting device 10 may include any one of the light guide plates 30 a to 30 k instead of the light guide plate 30 . In addition, the arrangement of the elongated prisms 37 in which two or more of arrangement examples 1 to 8 are arbitrarily combined can also be applied to the light guide plate included in the lighting device 10 . For example, as in the arrangement example 3, the long prisms 37 may be arranged in units of grids on the light guide plate provided in the lighting device 10, and the prism rows 38 as in the arrangement example 7 may be provided as the grids along the X-axis direction. borderline.

In addition, although the light source 20 is a so-called SMD type light emitting module, 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 is a diagram showing a modification of such a light source.

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

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, silicone resin, but may also be epoxy resin, urea resin, or the like. The sealing member 23 contains, for example, at least one of a yellow phosphor or a green phosphor. The sealing member 23 may contain a red phosphor in addition to at least one of a yellow phosphor or a green phosphor.

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 as compared with the light source 20 .

In addition, the light source used in the lighting device 10 may be a single-color LED, or may be a light-emitting module of a type in which a plurality of single-color LEDs are combined and mixed. The plural kinds of single-color LEDs are, for example, three kinds of single-color LEDs of RGB, but other combinations are also possible.

[Effect, etc.]

As described above, the light guide plate 30 includes: the first main surface 33; the side end surfaces (the first side end surface 35 and the second side end surface 36) provided at the ends along the first direction of the first main surface 33; and The first end surface 31 is provided along the first main surface 33 and at the end in the second direction intersecting with the first direction, and enters the light emitted by the light source. A plurality of elongated prisms 37 are provided on the first principal surface 33 with the first direction as the longitudinal direction. When the angle formed by the side surface of the long prism 37 on the light source 20 side and the first main surface 33 is the control angle, in the first prism group arranged in the first direction among the plurality of long prisms 37 , including elongated prisms 37 whose control angles are different from each other. The first direction is the X-axis direction in the above-mentioned embodiment, and the second direction is the Y-axis direction in the above-mentioned embodiment.

Such a light guide plate 30 can reduce uneven brightness on the irradiation surface.

In addition, in the light guide plate 30a, among the plurality of elongated prisms 37, the second prism group arranged in the second direction includes elongated prisms 37 whose control angles are different from each other.

Such a light guide plate 30a can improve the unevenness of light extraction in the entire light guide plate 30a and improve the light extraction efficiency. In addition, the unevenness of luminance in the irradiation surface can be reduced by easily dispersing the optical path inside the light guide plate 30a.

In addition, in the light guide plate 30, the plurality of elongated prisms 37 are aligned in the first direction and the second direction, respectively.

Such a light guide plate 30 can improve the appearance of the light emitting surface of the light guide plate 30 .

In addition, in the light guide plate 30b, the plurality of elongated prisms 37 are arranged in a staggered shape.

In such a light guide plate 30b, the light emitted from the light source 20 is more likely to be reflected by the elongated prism 37, thereby improving the light extraction efficiency.

Further, in the light guide plate 30e, a plurality of grids are provided on the first main surface 33, and the plurality of grids are regions in which the elongated prisms 37 having the same control angle are uniformly arranged.

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

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 smaller than that of the other two grids among the three grids. The control angle of the long prism 37 is larger, or smaller than the control angle of the long prism 37 belonging to the other two grids among the three grids.

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

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 in the second direction is smaller than that of the other two grids among the three grids. The control angle of the long prism 37 is larger, or smaller than the control angle of the long prism 37 belonging to the other two grids among the three grids.

With such a light guide plate 30e, effects such as reducing unevenness in luminance on the irradiated surface, improving the accuracy of optical design, and uniformizing light extraction can be obtained. In addition, since the pattern of the elongated prism 37 looks like a pattern and the pattern attracts attention, it is possible to reduce the appearance of the elongated prism 37 caused by a variation in processing or the like.

In addition, in the light guide plate 30e, if the thickness of the light guide plate 30e is t, and the solid angle at which 1/10 of the luminous flux incident on the light guide plate 30e is 2θ, the width W of the grid in the second direction is W The relational expression of t<W<2t/tanθ is satisfied.

In this way, if the width W satisfies such a relational expression, the light guide plate 30e in which the luminance unevenness of the irradiation surface is an allowable range can be realized with realistic processing time and cost.

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

Such a light guide plate 30f can realize a luminance distribution symmetrical to the first direction, and can reduce luminance unevenness in the first direction of the irradiation surface.

In addition, in the light guide plate 30g, 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 first direction, the first main surface 33 is provided in the first region R1 and the second region R2 on the light source 20 side. The average value of the control angles of the elongated prisms 37 in the region R1 is smaller than the average value of the control angles of the elongated prisms 37 provided in the second region R2.

In this way, the light guide plate 30g can efficiently take out broad light. In addition, the light guide plate 30g can increase the light extraction amount of the entire light guide plate 30g.

In addition, in the light guide plate 30h, the first principal surface 33 is provided with a continuous conical prism 38, which is formed by connecting the conical prisms in the first direction by a length corresponding to the longitudinal direction of the elongated prism 37. to make.

Such a light guide plate 30h can reduce unevenness in luminance on the irradiation surface by realizing a luminance distribution that cannot be realized only by the elongated prisms 37 .

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

Such a light guide plate 30j can reduce the unevenness of brightness on the irradiation surface, especially the unevenness of brightness in the shape of a rib.

In addition, in the light guide plate 30, the difference between the control angles of the elongated prisms 37 whose control angles are different from each other is 1° or more and 55° or less.

Such a light guide plate 30 can reduce unevenness in luminance on the irradiated surface by controlling various types of elongated prisms 37 having a difference in angle of 1° or more and 55° or less.

Further, the lighting device 10 includes a light guide plate 30 and a light source 20 .

Such a lighting device 10 can reduce unevenness in luminance on the irradiation surface.

Further, for example, the light source 20a has a linear light-emitting region along the first direction.

The illuminating device 10 provided with such a light source 20a can reduce the brightness unevenness (graininess) of the irradiation surface.

(Other Embodiments)

As mentioned above, although embodiment was demonstrated, this invention is not limited to the said embodiment.

In the above-described embodiments, the wall lamp is exemplified as the lighting device, but the present invention can be implemented as another lighting device. For example, the present invention can be implemented as a pole lamp installed outdoors, or as a foot lamp installed under a 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 desk lamp. The present invention can also be implemented as another lighting device using a light guide plate.

In the above-described embodiments, a light-emitting module using LEDs is used as the light source, but a light-emitting module including solid-state light-emitting elements other than LEDs such as organic EL (Electro-Luminescence) elements or inorganic EL elements may be used as the light source.

In addition, in the above-described embodiment, the light guide plate having a rectangular shape in plan view was exemplified as the light guide plate, but a light guide plate of another shape may be used in the lighting device.

In addition to the above, each embodiment can be realized by applying various modifications that those skilled in the art can think of, or by arbitrarily combining constituent elements and functions of each embodiment without departing from the gist of the present invention. Forms are also included in the present invention.

Claims (15)

1. A light guide plate is characterized in that,

the disclosed device is provided with:

a main face;

a side end surface provided at an end portion in the 1 st direction along the main surface; and

an end surface provided at an end portion in a 2 nd direction intersecting the 1 st direction along the main surface, the end surface being on which light emitted from a light source is incident;

a plurality of elongated prisms arranged on the main surface with the 1 st direction as a longitudinal direction;

when an angle formed by the side surface of the elongated prism on the light source side and the main surface is a control angle, the elongated prisms are included in a 1 st prism group arranged along the 1 st direction among the plurality of elongated prisms, the control angles being different from each other.

2. The light guide plate according to claim 1,

the 2 nd prism group arranged along the 2 nd direction among the plurality of elongated prisms includes the elongated prisms having the different control angles.

3. The light guide plate according to claim 1,

the plurality of elongated prisms are aligned in the 1 st direction and the 2 nd direction, respectively.

4. The light guide plate according to claim 1,

the plurality of elongated prisms are arranged in a staggered pattern.

5. The light guide plate according to claim 1,

a plurality of grids are provided on the main surface, and the plurality of grids are regions in which the long prisms having the same control angle are arranged in a unified manner.

6. The light guide plate according to claim 5,

the control angle of the elongated prism belonging to the grid at the center among the 3 grids arranged along the 1 st direction is larger than the control angle of the elongated prisms belonging to the other 2 grids among the 3 grids, or smaller than the control angle of the elongated prisms belonging to the other 2 grids among the 3 grids.

7. The light guide plate according to claim 5,

the control angle of the elongated prism belonging to the grid at the center among the 3 grids arranged along the 2 nd direction is larger than the control angle of the elongated prism belonging to the other 2 grids among the 3 grids, or smaller than the control angle of the elongated prism belonging to the other 2 grids among the 3 grids.

8. The light guide plate according to claim 5,

when the thickness of the light guide plate is t and the solid angle of the light flux entering the light guide plate is 1/10 is 2 theta, the width W of the grid in the 2 nd direction satisfies the relational expression of t < W <2t/tan theta.

9. The light guide plate according to claim 1,

the arrangement of the elongated prisms having the same control angle is symmetrical with respect to a 2 nd virtual straight line that bisects the main surface in the 2 nd direction.

10. The light guide plate according to claim 1,

when the main surface is divided into a 1 st region and a 2 nd region on the light source side by a 1 st virtual straight line along the 1 st direction, an average value of the control angles of the elongated prisms provided in the 1 st region is smaller than an average value of the control angles of the elongated prisms provided in the 2 nd region.

11. The light guide plate according to claim 1,

the principal surface is provided with a conical continuous prism formed by connecting conical prisms in the 1 st direction by a length corresponding to the longitudinal direction of the elongated prism.

12. The light guide plate according to claim 11,

the plurality of conical continuous prisms arranged along the 1 st direction are positioned on the light source side most among the prisms provided on the main surface.

13. The light guide plate according to any one of claims 1 to 12,

the difference in control angles between the long prisms having different control angles is 1 ° or more and 55 ° or less.

14. A lighting device is characterized in that a lamp body is provided,

the disclosed device is provided with:

the light guide plate according to any one of claims 1 to 13; and

the light source is described above.

15. The illumination device of claim 14,

the light source has a linear light emitting region along the 1 st direction.

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