JP7162181B2 - Light guide plate and lighting device - Google Patents

Description

The present disclosure relates to a light guide plate and a lighting device that guide and emit incident light.

2. Description of the Related Art Light guide plates are used in lighting devices such as surface lighting fixtures that are thin and emphasize design.

Patent Literature 1 describes a structure in which a light guide plate having a plurality of surfaces and capable of transmitting light has a plurality of groove-shaped prisms repeatedly positioned on a surface different from the light incident surface. A cross-sectional shape perpendicular to the longitudinal direction of each prism is substantially triangular. In such a light guide plate, the light incident from the light source into the light guide plate is reflected by the surfaces of the prisms and emitted from the surface of the light guide plate opposite to the surface on which the prisms are located.

JP-A-11-219609

When a light reflecting part such as a prism is processed unevenly in a light guide plate, when a person looks at the light guide plate from the outside of the light emitting surface (light emitting surface), the processing unevenness is recognized as luminance unevenness. easier. Such luminance unevenness causes a loss of marketability in terms of design of the lighting fixture. On the other hand, it is conceivable to increase the processing accuracy of the prisms in order to eliminate the processing unevenness, but in this case processing time becomes longer and the processing cost increases. Further, when groove-shaped prisms are formed on the light guide plate, the processing operation tends to be long.

An object of the present disclosure is to provide a light guide plate and a lighting device in which luminance unevenness due to processing unevenness is hardly recognized and which has excellent workability.

A light guide plate according to the present disclosure includes a light guide plate portion that has a plurality of surfaces, has a predetermined thickness, guides and emits incident light, and faces a direction different from the thickness direction of the light guide plate portion. The first surface of the light guide plate is an incident surface on which light can enter, and the second surface, which is one surface of both side surfaces in the thickness direction of the light guide plate, reflects the light that has entered the inside from the first surface. A plurality of dot-shaped reflection portions, each of which is a prism or a reflector, is formed or arranged, and the third surface, which is the other surface of both sides in the thickness direction of the light guide plate portion, is a light emission surface. and on the second surface, when viewed from the outside, a combination of a plurality of types of regions having different effective areas of dot-shaped reflective portions per unit area are positioned with a certain periodicity. be.

Further, an illumination device according to the present disclosure is an illumination device including the light guide plate according to the present disclosure and a light source that irradiates light from the first surface of the light guide plate to the inside of the light guide plate.

According to the light guide plate and the lighting device according to the present disclosure, when the interval between adjacent dot-shaped reflective portions in each region is minimized to the extent that a person cannot directly see and recognize it, the light guide plate is placed on the third surface. When viewed from the side toward the second surface, the luminance changes, and it is easy to recognize that there is a pattern with a certain periodicity. As a result, luminance unevenness due to processing unevenness becomes difficult to recognize, and the dot-shaped reflecting portions do not need to be processed with excessively high precision, so that a light guide plate with excellent workability and an illumination device including the light guide plate can be obtained. be done.

It is the figure seen from the 3rd surface side of the light-guide plate part of the illuminating device containing the light-guide plate of embodiment. FIG. 2 is an enlarged equivalent view of part A of the light guide plate shown in FIG. 1 when viewed from the second surface side; 3 is a perspective view showing a first prism concave portion and a second prism concave portion shown in FIG. 2; FIG. It is an enlarged view of the 2nd surface of the light-guide plate of another example of embodiment. 5 is an enlarged perspective view showing a part of the light guide plate having the second surface shown in FIG. 4; FIG. It is an enlarged view of the 2nd surface of the light-guide plate of another example of embodiment. A diagram (a) of a lighting device according to another example of the embodiment as seen from the third surface side of the light guide plate portion, and an enlarged view corresponding to the B portion of the light guide plate portion shown in (a) as viewed from the second surface side ( b). It is an enlarged view of the 2nd surface of the light-guide plate of another example of embodiment. It is an enlarged view of the 2nd surface of the light-guide plate of another example of embodiment. FIG. 10 is a perspective view showing an enlarged part of the light guide plate having the second surface shown in FIG. 9; It is a perspective view which expands and shows a part of light-guide plate of another example of embodiment. It is a perspective view which expands and shows a part of light-guide plate of another example of embodiment. It is the figure (a) which shows the 2nd surface of the light-guide plate of another example of embodiment, the C section enlarged view (b) of (a), and the D section enlarged view (c) of (a).

Hereinafter, an example of an embodiment of a lighting device according to the present disclosure will be described in detail with reference to the drawings. Since the drawings referred to in the description of the embodiments are schematically described, the dimensional ratios of each component should be determined with reference to the following description. In the following description, specific shapes, materials, quantities, etc. are examples for facilitating understanding of the present disclosure, and can be appropriately changed according to the specifications of the lighting device. In addition, it is assumed from the beginning to selectively combine each component of a plurality of embodiments described below. In the following description, similar elements are denoted by the same reference numerals in all drawings.

(Structure of lighting device)
FIG. 1 is a diagram of a lighting device 10 including a light guide plate 12 according to an embodiment of the present disclosure, viewed from the third surface 16 (light exit surface) side of the light guide plate portion 13 . FIG. 2 is an enlarged view corresponding to part A of the light guide plate portion 13 shown in FIG. 1 when viewed from the second surface 15 side. The lighting device 10 includes a light guide plate 12 , a fixture body 50 , a light emitting module 52 and a power source section 55 . The light guide plate 12 includes a light guide plate portion 13 which is a rectangular thin plate member having six surfaces and a predetermined thickness. The light guide plate portion 13 guides and emits incident light. The light guide plate portion 13 is made of, for example, a translucent resin material such as polycarbonate or acryl. The six surfaces of the light guide plate portion 13 are a first surface 14 perpendicular to the thickness direction (front and back directions of the paper surface of FIG. 1), and second surfaces 15 (FIG. 2) and third surfaces (FIG. 2) on both sides in the thickness direction. 1). The first surface 14 is a surface orthogonal to the second surface 15 and is an incident surface on which light is incident. The first surface 14 faces in a direction different from the thickness direction of the light guide plate portion 13 . The second surface 15 is one of both sides in the thickness direction of the light guide plate portion 13 (the front surface of the paper surface of FIG. 1), and is a surface on which a plurality of prisms, which will be described later, are formed as a plurality of dot-shaped reflecting portions. . The third surface is the other side surface (back side surface of the paper surface of FIG. 1) of both side surfaces in the thickness direction of the light guide plate portion 13, and is an emission surface from which light is emitted.

The device main body 50 is a case-shaped member in which the light guide plate 12 is fixed with the end portion of the light guide plate 12 inserted inside, and the light emitting module 52 and the power source section 55 are mounted inside.

The light emitting module 52 is fixed to the fixture body 50 so as to face the vicinity of the first surface 14 of the light guide plate 12 . The light-emitting modules 52 are attached at a plurality of positions in the longitudinal direction (horizontal direction in FIG. 1) of the substrate 53 arranged substantially parallel to the first surface 14 and the surface of the substrate 53 facing the first surface 14 of the light-emitting module 52 . and a plurality of LED elements 54 which are light sources.

The plurality of LED elements 54 emit light from the first surface 14 into the light guide plate 12 . The light entering the light guide plate 12 is reflected by the prism surface of the second surface 15 and emitted from the third surface 16 . The LED element 54 is, for example, an SMD (Surface Mount Device) type. An SMD type LED element is a package type LED element in which an LED chip (light emitting element) is mounted in a resin-molded cavity and the cavity is filled with a phosphor-containing resin. The LED element 54 is connected to the power supply section 55 via a switch section (not shown) such as a semiconductor switch, and the ON/OFF state of the switch section is controlled by a control section (not shown). As a result, the LED element 54 is switched between lighting and extinguishing. In addition, the LED element 54 may be controlled by the control unit to perform dimming and color adjustment.

The light source is not limited to such a configuration, and a COB (Chip On Board) type light emitting module in which an LED chip is directly mounted on a substrate may be used. Further, the light source is not limited to an LED element, and may be, for example, a semiconductor light emitting element such as a semiconductor laser, or an EL element such as an organic EL (Electro Luminescence) or an inorganic EL.

(Prism structure)
As shown in FIG. 2, when a part of the second surface 15 of the light guide plate portion 13 is enlarged and viewed from the outside, the second surface 15 has two types of band-like regions each including a plurality of prisms. . The two types of strip-shaped regions are the first region 20, which is a strip-shaped region including first prisms 22 as a plurality of first dot-shaped reflecting portions, and the strip-shaped region including second prisms 32 as a plurality of second dot-shaped reflecting portions. It is the second region 30 which is a region.

The first region 20 and the second region 30 are the dot-shaped reflecting portions (first prism 22, second prism 32 ) have different effective areas. The first area 20 and the second area 30 have different types of first prisms 22 and second prisms 32 in the first area 20 and the second area 30 . In this example, the "different types" are the areas of the second surfaces 15 of the first prism 22 and the second prism 32 when viewed from the outside, and the size and shape of the first prism 22 and the second prism 32. different. Specifically, in the first region 20, a plurality of first prisms 22 are arranged at equal intervals in a linear first direction or in a direction parallel to the first direction. The first direction is parallel to the longitudinal direction when the light guide plate portion 13 is viewed from one side in the thickness direction. 1 and 2, the longitudinal direction is indicated by X, and the lateral direction when the light guide plate portion 13 is viewed from one side in the thickness direction is indicated by Y. As shown in FIG.

In the second region 30, a plurality of second prisms 32 are arranged at regular intervals in a direction parallel to the first direction.

FIG. 3 is a perspective view showing the first prism 22 and the second prism 32. FIG. In FIG. 3, the second surface 15 is shown as sandy. The first prism 22 is a concave portion of an elliptical conical surface with an elliptical cross section formed so as to be depressed inside from the second surface 15 . The longitudinal direction of the elliptical cross-sectional shape of the first prism 22 coincides with the first direction or a direction parallel to the first direction.

The second prism 32 is a conical concave portion with a circular cross section that is recessed inward from the second surface 15 . The area of the circular aperture 33 that is the open end of the second prism 32 is smaller than the area of the elliptical aperture 23 that is the open end of the first prism 22 . Also, the depth of the second prisms 32 in the thickness direction of the light guide plate portion 13 (front and back directions of the paper surface of FIG. 2) is smaller than the depth of the first prisms 22 in the thickness direction of the light guide plate portion 13 .

In FIG. 2, the number of first prisms 22 in the first area 20 and the number of second prisms 32 in the second area 30 are the same, and the second prisms 22 are located at the center position between the first prisms 22 adjacent in the X direction. Although the case where the prism 32 is located is shown, it is not limited to this. In addition, in FIG. 2, the boundary between the first region 20 and the second region 30 is indicated by a dashed-dotted line in order to facilitate understanding, but such a dashed-dotted line is not actually formed on the second surface 15. .

The plurality of first regions 20 are arranged on the second surface 15 at equal intervals in a direction (Y direction) orthogonal to the first direction. A plurality of second regions 30 are located at central positions between adjacent first regions 20 . Thus, on the second surface 15, the plurality of first regions 20 and the plurality of second regions 30 are alternately positioned one by one in the direction orthogonal to the first direction.

Furthermore, on the second surface 15, the effective area of the first prism 22 per unit area of the first region 20 is the first area S1 when viewed from the outside (the front side of the paper surface of FIG. 2). The effective area of the second prism 32 per unit area of 30 is the second area S2. The second area S2 is smaller than the first area S1 (S2<S1). As a result, when viewed from the outside, the second surface 15 has a combination of the first regions 20 and the second regions 30 having different effective areas of the dot-shaped reflective portions per unit area in a direction orthogonal to the first direction. are located with a certain periodicity about . Here, "combination" means that the first region 20 and the second region 30 are positioned adjacent to each other in a direction orthogonal to the first direction. Therefore, as shown in FIG. 2 , when viewed from the outside of the second surface 15 , the elliptical apertures 23 of the plurality of first prisms 22 are located in the first region 20 , and the plurality of prisms 22 are located in the second region 30 . A circular aperture 33 of the second prism 32 is located. In the first region 20 and the second region 30, the widths D1 and D2 in the direction perpendicular to the first direction are set so that the width D1 of the first region 20 is larger than the width D2 of the second region 30. Although different, the widths D1 and D2 may be the same.

Further, the second surface 15 is formed with neither groove-like prisms nor protrusion-like prisms.

The first prism 22 and the second prism 32 are formed by thermal processing such as laser processing, for example. The first prism 22 and the second prism 32 are easier to process in a short period of time than when groove-shaped prisms or striation-shaped prisms are formed. In particular, when the dot-shaped first prisms 22 and the second prisms 32 are formed by thermal processing, it takes an extremely short time compared to the case of forming groove-shaped prisms or ridge-shaped prisms by mechanical processing. can be processed.

By forming a plurality of first prisms 22 and second prisms 32 on the second surface 15 in this way, the light from the LED elements 54 entering the light guide plate 12 from the first surface 14 is directed to the light guide plate 12 . go inside the Then, the light becomes reflected light reflected by the surface of the first prism 22 or the second prism 32 and is emitted to the outside of the light guide plate 12 from the third surface 16 (FIG. 1).

Since the light guide plate 12 is configured in this manner, the distance between the adjacent first prisms 22 and the distance between the adjacent second prisms 32 are set to such an extent that a person cannot directly visually recognize them (without using a microscope or the like). When the light guide plate 12 is minimized, it looks as shown in FIG. 1 when the light guide plate 12 is viewed from the side of the third surface 16 toward the second surface 15 . FIG. 1 shows a state in which the light from the light emitting module 52 is emitted from the third surface 16. As shown in FIG. In this case, on the second surface 15, the first direction and a plurality of straight lines parallel to the first direction are alternately positioned in a direction orthogonal to the first direction, and the brightness of the straight lines alternately changes and is constant. It is easy to recognize that there is a pattern with periodicity. In FIG. 1, the straight line α schematically shows that it looks like a straight line with high brightness, and the dashed line β shows that it looks like a straight line with low brightness. A straight line α corresponds to the first region 20 (FIG. 2). A dashed line β corresponds to the second region 30 (FIG. 2). That is, the brightness is high at the position where the first prism 22 with a large effective area is formed, and the brightness is low at the position where the second prism 32 with a small effective area is formed. By recognizing that there is a pattern when viewed from the third surface 16 in this way, when processing unevenness occurs in a part of the first prism 22 and the second prism 32, luminance unevenness based on the processing unevenness is eliminated. becomes difficult for people to recognize. In particular, by reducing the distance between the prisms 22 and 32 in the regions 20 and 30 to such an extent that a person cannot directly see and recognize it, the luminance unevenness becomes more difficult for a person to recognize.

In this example, since the first regions 20 and the second regions 30 are alternately positioned in the direction orthogonal to the first direction, it is likely to look like a horizontal line pattern in which the density changes alternately. By recognizing this pattern, luminance unevenness due to processing unevenness of the prisms 22 and 32 less than the density difference of the pattern that can be directly recognized by a person based on the difference in the effective area of the prisms 22 and 32 is less likely to be recognized. Therefore, the apparent quality of the light guide plate 12 can be improved. Moreover, since it is not necessary to process the prisms 22 and 32 with excessively high precision, it is possible to realize the light guide plate 12 excellent in workability and the illumination device 10 including the light guide plate 12 .

FIG. 4 is an enlarged view of the second surface 15a of the light guide plate 12a of another example of the embodiment. FIG. 5 is a perspective view showing an enlarged part of the light guide plate 12 having the second surface 15a shown in FIG. In the configuration of this example, the first regions 20a and the second regions 30a are alternately positioned in the direction perpendicular to the first direction on the second surface 15a. In the first region 20a, a plurality of first prisms 22a, which are conical recesses with a circular cross section, are arranged in a first direction or in a direction parallel to the first direction. Therefore, as shown in FIG. 4, when viewed from the outside of the second surface 15, circular openings 24, which are opening ends of the plurality of first prisms 22a, are positioned in the first region 20a. Furthermore, the second prism 32a is similar in shape to the first prism 22a and smaller than the first prism 22a. Therefore, the area of the circular opening 33a of the second prism 32a is smaller than the area of the circular opening 24 of the first prism 22a. Also, the first prism 22a and the second prism 32a have the same prism angle θ, which is the inclination angle with respect to the plane including the portions other than the first prism 22a and the second prism 32a on the second surface 15a.

The first area 20a and the second area 30a have first prisms 22a and second prisms 32a of different types in the first area 20a and the second area 30a. In this example, the “different types” are different areas of the first prism 22a and the second prism 32a when viewed from the outside of the second surface 15a, and different sizes of the first prism 22a and the second prism 32a. there is Other configurations and actions in this example are the same as those in FIGS. In addition, in the configuration of this example, both the first prism and the second prism may be concave portions of an elliptical conical surface having an elliptical cross section.

FIG. 6 is an enlarged view of the second surface 15b of the light guide plate 12b of another example of the embodiment. In the configuration of this example, a plurality of first regions 60 and a plurality of second regions 70 are positioned on the second surface 15b of the light guide plate 12b. The first area 60 is a parallelogram area in which the four first prisms 22a as the first dot-shaped reflecting portions are positioned at the four vertices of the parallelogram. The second area 70 is a parallelogram area in which the second prisms 32a as four second dot-shaped reflecting portions are positioned at the four vertices of the parallelogram. The first area 60 and the second area 70 have the same size.

The first prism 22a and the second prism 32a are conical concave portions, respectively, similar to the configurations of FIGS. The area of the second prism 32a when viewed from the outside of the second surface 15b is smaller than that of the first prism 22a. As a result, when viewed from the outside on the second surface 15b, the effective area of the second prisms 32a per unit area of the second region 70 is greater than the effective area of the first prisms 22a per unit area of the first region 60. area is small.

The plurality of first regions 60 are arranged in a linear first direction inclined with respect to the longitudinal direction X and the lateral direction Y of the light guide plate portion 13 or parallel to the first direction so as to form grid lines of the grid portion. located so that they are connected in the same direction. The plurality of first regions 60 are also connected in a direction perpendicular to the first direction. A plurality of second regions 70 are located in portions of the grid portion other than the grid lines (portions serving as openings of the grid portion). The plurality of second regions 70 are connected in a direction parallel to the first direction, and the plurality of second regions 70 are also connected in a direction perpendicular to the first direction. As a result, when viewed from the outside, the second surface 15 has the first region 60 and the second region 70 having different effective areas of the dot-shaped reflective portions per unit area. , and also alternately in a direction inclined with respect to the longitudinal direction X (direction of arrow γ in FIG. 6). Therefore, the combination of the first regions 60 and the second regions 70 is positioned with a certain periodicity on the second surface 15b. Here, the “combination” means that the first region 60 and the second region 70 are positioned adjacent to each other in the longitudinal direction X of the light guide plate portion 13 and in a direction inclined with respect to the longitudinal direction X. As shown in FIG.

With the above configuration, the light guide plate 12b is viewed from the third surface side toward the second surface 15b when the interval between the adjacent first prisms 22a and the interval between the adjacent second prisms 32a are minimized. In this case, it is easy to perceive that there is a slanted grid pattern with alternating brightness and constant periodicity. At this time, the plurality of first regions 60 looks like grid lines of a high-brightness diagonal grid. As a result, when processing unevenness occurs in a part of the first prism 22a and the second prism 32a, it becomes difficult for people to recognize luminance unevenness based on the processing unevenness. In this example, other configurations and actions are the same as the configurations in FIGS. 1 to 3 or the configurations in FIGS.

7A and 7B are a view of the light guide plate portion 13 of the lighting device 10a according to another example of the embodiment viewed from the third surface 16 side, and a view of the light guide plate portion 13 shown in FIG. 7A from the second surface 15c side. FIG. 11(b) is an enlarged view corresponding to the B portion in the case of the case shown in FIG. In the configuration of this example, in the second surface 15c of the light guide plate 12c, when viewed from the outside, the plurality of first regions 62 and the plurality of second regions 72 extend in the lateral direction Y of the light guide plate portion 13, alternately one each.

Also, the first area 62 and the second area 72 have the first reflection group 63 and the second reflection group 73 of different types in the first area 62 and the second area 72 . In this example, the first reflection group 63 and the second reflection group 73 have different effective areas and shapes of the dot-shaped reflection portions when viewed from the outside of the second surface 15c.

Specifically, the first region 62 is a band-shaped region in which a plurality of first reflection groups 63 are arranged at regular intervals in the first linear direction or in a direction parallel to the first direction. The first reflection group 63 is formed by gathering a plurality of first prisms 64 . Adjacent first prisms 64 in the first reflection group 63 are closer than the interval between the first reflection groups 63 . The first prism 64, like the second prism 32 in the configuration of FIGS. 1-3 and the prisms 22a, 32a in the configurations of FIGS. 4 and 5, is a conical recess. The first reflection group 63 is formed of a total of seven first prisms 64, one at the center and six positioned at the vertices of a regular hexagon around the center.

The second area 72 is a belt-like area in which a plurality of second reflection groups 73 are arranged in a direction parallel to the first direction at regular intervals. The second reflection group 73 is formed by gathering a plurality of first prisms 64 having the same shape and size as the first prisms 64 forming the first reflection group 63 . Adjacent first prisms 64 of the second reflection group 73 are closer than the interval between the second reflection groups 73 . The second reflection group 73 is formed by a total of five first prisms 64, one at the center and four located at the vertices of a square around the center. As a result, the second reflection group 73 has a plurality of first prisms 64 gathered in a form different from that of the first reflection group 63 . Also, when viewed from the outside of the second surface 15, the effective area per unit area of the first prism 64 in the second reflection group 73 is equal to the effective area per unit area of the first prism 22 in the first reflection group 63. Less than effective area. Also, the second reflection group 73 is positioned at the center position between the adjacent first reflection groups 63 in the direction parallel to the first direction.

Further, on the second surface 15c, a combination of the first regions 62 and the second regions 72 having different effective areas of the dot-shaped reflective portions per unit area when viewed from the outside has a certain periodicity. To position. Here, the “combination” means that the first region 62 and the second region 72 are positioned adjacent to each other in the lateral direction Y of the light guide plate portion 13 . In addition, the first region 62 and the second region 72 have the same width in the direction orthogonal to the first direction.

In the above configuration, similarly to the configuration of FIGS. and In this case, as in the configuration of FIGS. 1 to 3, when the light guide plate 12c is viewed from the side of the third surface 16 toward the second surface 15c, the first direction and the direction parallel to the first direction A plurality of straight lines are alternately positioned in a direction orthogonal to the first direction, and the brightness of the straight lines alternately changes, making it easy to perceive a pattern with a certain periodicity. Furthermore, since a plurality of first prisms 64 are gathered in each of the reflection groups 63 and 73, light streak unevenness occurs on the end portion of the light guide plate 12c near the light source due to the light diffusion effect of the first prisms 64 that are close to each other. easy to reduce. Other configurations and actions in this example are the same as those in FIGS.

FIG. 8 is an enlarged view of the second surface 15d of the light guide plate 12d of another example of the embodiment. In the configuration of this example, a plurality of first regions 65 and a plurality of second regions 75 are positioned on the second surface 15d of the light guide plate 12d. The first area 65 is a rectangular area in which the four first reflection groups 63 are positioned at the four vertices of the rectangle. The second area 75 is a rectangular area in which the four second reflection groups 73 are positioned at the four vertices of the rectangle. The first area 65 and the second area 75 have the same size.

The first reflection group 63 and the second reflection group 73 are the same as the first reflection group 63 and the second reflection group 73 of the configuration shown in FIG. The plurality of first regions 65 are arranged in a linear first direction inclined with respect to the longitudinal direction X and the lateral direction Y of the light guide plate portion 13 or parallel to the first direction so as to form grid lines of the oblique grid portion. Located so as to connect to the direction. The plurality of first regions 65 are also connected in a direction crossing the first direction. A plurality of second regions 75 are located in portions of the grid portion other than the grid lines (portions serving as openings of the grid portion). The plurality of second regions 75 are connected in a direction parallel to the first direction, and the plurality of second regions 75 are also connected in a direction crossing the first direction. As a result, on the second surface 15 d , the first region 65 and the second region 75 having different effective areas of the dot-shaped reflective portions per unit area when viewed from the outside are arranged in the longitudinal direction X of the light guide plate portion 13 . They are positioned alternately and are also positioned alternately in the transverse direction Y. Therefore, the combination of the first regions 65 and the second regions 75 is positioned with a certain periodicity on the second surface 15d. Here, the “combination” means that the first region 60 and the second region 70 are positioned adjacent to each other in the longitudinal direction X and the lateral direction Y of the light guide plate portion 13 .

Even with the above configuration, when the distance between the first prisms 64, the distance between the first reflection groups 63, and the distance between the second reflection groups 73 are minimized in each region, the light guide plate 12d is arranged on the third surface. When viewed from the side toward the second surface 15d, it is easy to recognize that there is a slanted grid pattern or a checkerboard pattern with a constant periodicity in which the luminance changes alternately. For example, the plurality of first regions 65 looks like grid lines of a high-brightness diagonal grid. As a result, when processing unevenness occurs in a part of the first prism 64, it becomes difficult for people to recognize luminance unevenness based on the processing unevenness. Other configurations and actions in this example are the same as the configuration in FIGS. 1 to 3 or the configuration in FIG.

FIG. 9 is an enlarged view of the second surface 15e of the light guide plate 12e of another example of the embodiment. FIG. 10 is a perspective view showing an enlarged part of the light guide plate 12e having the second surface 15e shown in FIG. In the configuration of this example, unlike the configurations of FIGS. 4 and 5, the first regions 20a and the second regions 30b are alternately positioned on the second surface 15e of the light guide plate 12e. The first region 20a is formed to include a plurality of first prisms 22a that are concave portions with conical surfaces. The second region 30b is formed to include a plurality of second prisms 32b, which are concave portions of rectangular cross-sections, for example, quadrangular quadrangular pyramid surfaces. Therefore, as shown in FIG. 9, the rectangular openings 34 of the plurality of second prisms 32b are positioned in the second region 30b when viewed from the outside of the second surface 15e. The area of the rectangular opening 34 is smaller than the area of the circular opening 24 of the first prism 22a.

The first area 20a and the second area 30b have different types of first prisms 22a and second prisms 32b in the first area 20a and the second area 30b. In this example, the "different types" are the areas of the first prism 22a and the second prism 32b when viewed from the outside of the second surface 15e, and the shape and size of the first prism 22a and the second prism 32b. there is In this example, other configurations and actions are the same as the configurations in FIGS. 1 to 3 or the configurations in FIGS.

FIG. 11 is a perspective view showing an enlarged part of a light guide plate 12f of another example of the embodiment. In the configuration of this example, the first regions 20b and the second regions 30a are alternately positioned in the direction perpendicular to the first direction on the second surface 15f of the light guide plate 12f. In this example, unlike the configuration shown in FIGS. 4 and 5, in the first region 20b, a plurality of disk-shaped reflectors 80 are arranged side by side in the first direction or in a direction parallel to the first direction. Therefore, when viewed from the outside of the second surface 15, a plurality of disk-shaped reflectors 80 are positioned in the first region 20b. The reflector 80 corresponds to a dot-shaped reflecting portion. The disk-shaped area of the reflector 80 is larger than the area of the circular opening 33a of the second prism 32a. The reflector 80 is formed, for example, by silk-printing ink having light reflectivity on the second surface 15f of the light guide plate 12f. ) is a printed portion with high diffusivity. The reflector 80 reflects the light incident inside from the first surface.

On the other hand, the second prism 32 a in the second region 30 a has a smaller diffusivity for the light incident on the light guide plate portion 13 than the reflector 80 . The reflector 80 is not limited to the printed portion as described above, and a film or sheet-like member having light reflectivity and high light diffusivity is attached to the second surface 15f with an adhesive or the like. It may be arranged by being placed.

The first region 20b and the second region 30a have different types of reflectors 80 and second prisms 32a in the first region 20b and the second region 30a. In this example, the “different types” are the areas of the second surface 15f of the reflector 80 and the second prism 32a when viewed from the outside, the shape and size of the reflector 80 and the second prism 32a, and the surface Diffusion of light is different.

Even with the above configuration, when the distance between the adjacent reflectors 80 and the distance between the adjacent second prisms 32a are minimized, when viewed from the third surface 16 side toward the second surface 15f, a straight line It is easy to recognize that there is a pattern with constant periodicity with alternating luminance. In this example, other configurations and actions are the same as the configurations in FIGS. 1 to 3 or the configurations in FIGS. In addition, in the configuration of this example, both the dot-shaped reflecting portions in the first region and the second region may be reflectors.

FIG. 12 is a perspective view showing an enlarged part of a light guide plate 12g of another example of the embodiment. In this example, unlike the configurations of FIGS. 4 and 5, the first regions 20c and the second regions 30a are alternately arranged on the second surface 15g of the light guide plate 12g. The first region 20c and the second region 30a are formed including first prisms 22b and second prisms 32a, respectively, which are a plurality of conical recesses. The second prism 32a is dissimilar to the first prism 22b and smaller than the first prism 22b. Specifically, the prism angle θ1 of the first prism 22b is larger than the prism angle θ2 of the second prism 32a with respect to the prism angle, which is the inclination angle with respect to the plane including the portions other than the prisms 22b and 32a on the second surface 15g. . Accordingly, the prism angle θ1 of the first prism 22b and the prism angle θ2 of the second prism 32a are different. Also, the area of the circular opening 33a of the second prism 32a is smaller than the area of the circular opening 24a of the first prism 22b.

The first area 20c and the second area 30a have first prisms 22b and second prisms 32a of different types in the first area 20c and the second area 30a. In this example, the "different types" are the areas of the second surfaces 15g of the first prism 22b and the second prism 32a when viewed from the outside, the shape, size, and prism angle of the first prism 22b and the second prism 32a. is different. In this example, other configurations and actions are the same as the configurations in FIGS. 1 to 3 or the configurations in FIGS.

FIG. 13 is a diagram (a) showing a second surface 15h of a light guide plate 12h of another example of the embodiment, an enlarged view (b) of part C in (a), and an enlarged view (c) of part D in (a) is. The configuration of this example is a combination of the configuration of FIG. 7 and the configuration of FIG. Specifically, on the second surface 15 h , the first regions 62 a and the second regions 72 a are alternately positioned one by one in the short direction Y of the light guide plate portion 13 . In the first region 62a, a plurality of first reflection groups 63a are arranged at regular intervals in the first direction or in a direction parallel to the first direction. formed together. In the second region 30, a plurality of second reflection groups 73a are arranged at equal intervals in a direction parallel to the first direction, and the second reflection groups 73a are formed by gathering a plurality of second prisms 74a. be.

The first prism 64a and the second prism 74a are conical concave portions, and the circular opening areas of the first prism 64a and the second prism 74a are the same when the second surface 15h is viewed from the outside. On the other hand, the prism angle θ1a of the first prism 64a is larger than the prism angle θ2a of the second prism 74a.

The first area 62a and the second area 72a have the first reflection group 63a and the second reflection group 73a of different types in the first area 62a and the second area 72a. In this example, the "different types" include the effective area of the prisms when viewed from the outside of the second surfaces 15h of the first reflection group 63a and the second reflection group 73a, the shapes of the first prism 64a and the second prism 74a, The sizes and prism angles θ1a and θ2a are different.

In the configuration of this example, when the prisms are formed by thermal processing, there is a possibility that the prism angles cannot be stably formed due to local thermal or material environmental factors. In this case, according to the above configuration, the prism angles θ1a and θ2a are different between the first reflection group 63a and the second reflection group 73a. As a result, when the variation in prism angle is equal to or less than the difference in prism angle between the first reflection group 63a and the second reflection group 73a, the light guide plate 12h is viewed from the third surface side toward the second surface 15h. In this case, a pattern (horizontal line pattern) corresponding to the arrangement of the combinations of the reflecting groups with different prism angles is easily recognized. Therefore, luminance unevenness due to processing unevenness is less likely to be recognized, and the apparent quality of the light guide plate 12 is improved. In this example, other configurations and actions are the same as the configurations in FIGS. 1 to 3 or the configurations in FIGS.

As in the above examples, the plurality of types of regions on the second surface of the light guide plate portion have different types of dot-shaped reflecting portions in the plurality of types of regions, or different types of reflection groups in the plurality of types of regions. It is conceivable to configure In this case, by minimizing one or both of the interval between adjacent dot-shaped reflective portions and the interval between adjacent reflective groups in each region, when viewed from the third surface side toward the second surface, In addition, it is easier to recognize that there is a pattern with constant periodicity with varying brightness. In this case, "different types" means, for example, in a plurality of dot-shaped reflecting portions or reflecting groups, the area, size, shape, and number of reflecting groups when viewed from the outside of the second surface of the dot-shaped reflecting portions. At least one of the effective area and shape of the dot-shaped reflective portions when viewed from the outside of the two surfaces, the prism angle when the dot-shaped reflective portions are prisms, and light diffusivity is different. In each of the above examples, a case has been described in which two types of regions are included in a combination of multiple types of regions, but the combination may include three or more types of regions.

In the above examples, the prism is a concave portion formed on the second surface. A prism as a dot-shaped reflecting portion may be used. 1 to 10, 12 and 13, the reflector having the structure shown in FIG. 11 can be used instead of the prism. For example, in the configurations of FIGS. 4 and 5, a plurality of reflectors having different sizes in the first area and the second area can be arranged on the second surface.

Further, the light guide plate is not limited to the rectangular plate shape as in each of the above examples, and may be a disk shape. In this case, a through hole penetrating in the thickness direction may be formed in the central portion of the light guide plate. At this time, one radial side surface of the light guide plate serves as an incident surface on which light from the light source is incident.

10,10a illumination device, 12,12a-12h light guide plate, 13 light guide plate portion, 14 first surface, 15,15a-15h second surface, 16 third surface, 20,20a-20c first region, 22,22a , 22b first prism, 23 elliptical aperture, 24, 24a circular aperture, 30, 30a, 30b second region, 32, 32a, 32b second prism, 33, 33a circular aperture, 50 fixture body, 52 light emitting module, 53 substrate , 54 LED element, 55 power supply unit, 60, 62, 62a first region, 63, 63a first reflection group, 64, 64a first prism, 65 first region, 70, 72, 72a second region, 73, 73a Second reflecting group, 74a Second prism, 75 Second area, 80 Reflector.

Claims (2)

A light guide plate portion having a plurality of surfaces, having a predetermined thickness, and guiding and emitting incident light,
a first surface of the surfaces facing in a direction different from the thickness direction of the light guide plate portion is an incident surface on which light can enter;
A second surface, which is one surface of both side surfaces in the thickness direction of the light guide plate portion, has a plurality of dot-shaped reflecting portions that reflect the light incident inside from the first surface . a plurality of dot-shaped reflecting portions are formed or arranged,
a third surface, which is the other surface on both sides in the thickness direction of the light guide plate portion, is a light exit surface;
On the second surface, when viewed from the outside, the effective area of the dot-shaped reflective portions per unit area is the first area, and the plurality of first small dot-shaped reflective portions are close to each other and are the same as a whole. A plurality of the first reflection groups, which are the dot-shaped reflection portions gathered to form an outer shape, are arranged in a first direction parallel to the incident surface, or in a strip shape aligned in a direction parallel to the first direction When viewed from the outside, the effective area of the dot-shaped reflective portions per unit area is a second area smaller than the first area, and the plurality of second small dot-shaped reflective portions are A plurality of the second reflection groups, which are the dot-shaped reflection portions that are close to each other and gather to form the same outline as a whole, are strip-shaped regions that are aligned in a direction parallel to the first direction. 2 regions are alternately arranged in a predetermined number in a direction orthogonal to the first direction,
Light guide plate. A light guide plate according to claim 1 ;
a light source that irradiates light from the first surface of the light guide plate into the interior of the light guide plate;
lighting device.

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