TWI479207B - Light guide panel - Google Patents

Description

Light guide panel

The present invention relates to a light guide panel. Specifically, it relates to a light-emitting panel used in a planar light-emitting device for illumination or display, which is incorporated in a mobile device such as a mobile phone.

(general planar light-emitting device)

Fig. 1 is a schematic plan view schematically showing a planar light-emitting device using a light guide panel, which is displayed during light emission. Fig. 2 is a cross-sectional view taken along the line X-X in Fig. 1. The planar light-emitting device takes light emitted from the light source into the light guide panel and expands into a planar shape, and emits light from a predetermined light-emitting area on the surface of the light guide panel.

As shown in FIG. 1, the planar light-emitting device 11 has the light guide panel 13 stacked on the surface of the substrate 12, and the light source 14 is mounted on the substrate 12 at a position facing the light incident end surface 15 of the light guide panel 13. By. On the back surface of the light guide panel 13, as shown in Fig. 2, the display region 16 is formed to face the predetermined light-emitting region where light is to be emitted. In the example of the drawing, the display area 16 is formed by recessing a plurality of fine triangular-shaped diffusion patterns 17 on the entire surface of the back surface of the light guide panel 13 in the letter "A". The surface on the light source side of the diffusion pattern 17 forms an inclined surface of about 45°. The light source 14 is an LED light source in which an LED chip is sealed in a resin case, and has a width smaller than a width of an light incident end surface of the light guide panel 13. The light source 14 has its light exit surface arranged close to the light incident end surface 15 of the light guide panel 13.

In the planar light-emitting device 11, when the light source 14 is turned on, the light emitted from the light source 14 enters the light guide panel 13 from the light incident end surface 15. As shown by the arrow in FIG. 2, the light incident on the light guide panel 13 is repeatedly reflected on the front and back surfaces of the light guide panel 13, thereby being diffused to the entire light guide panel 13, and The light that is totally reflected by the diffusion pattern 17 in the middle is emitted from the surface of the light guide panel 13 toward the front. As a result, when the planar light-emitting device 11 is viewed from the front, only the display region 16 (for example, the region of the letter "A" in the first drawing) is brightly illuminated.

However, in the light guide panel 13, there is actually a region B where light is not guided as in the hatched region in the first figure. Therefore, when the display area 16 is provided in the area B as shown in Fig. 1, the display area 16 in the area B does not emit light, for example, a portion lacking the letter "A".

The reason why the light guiding light is not performed in the area B is as follows. Even if the light emitted from the light source 14 has a 90° spread on both sides with respect to the central axis of the light (through the center of the light source 14 and perpendicular to the axis of the light radiating surface of the light source 14), since the light is incident on the end face from the light 15 is refracted when it enters the light guide panel 13, so that the range in which the light expands in the light guide panel 13 is centered on the central axis of the light, and the angle is θ (<90° on both sides of the center); Corner) The area that is expanded. The spread angle θ is a value equal to a critical angle at which the refractive index of the resin is generated. For example, if the refractive index n of the light guide panel 13 is 1.59, according to Sinae's law, θ=arcsin.(1/n)≒39° . Thereby, light guiding is not performed in the region B outside the respective line segments extending from the position opposite to the light incident end surface 15 at the expanded angle θ.

Further, since the alignment of the light radiated from the light source 14 is substantially a Lange distribution, the alignment of the light incident on the light guide panel 13 is also in the direction of the central axis of the light, and the light intensity is large, and the When the central axis of the light forms a large angle, the light intensity is smaller. Therefore, even if the display region 16 is provided so as not to overlap the region B where the light is not guided, there is a case where the central portion of the display region 16 is brightly illuminated, but both ends are darkened.

In order to avoid these undesirable conditions, as shown in FIG. 3, although the display area 16 can be sufficiently away from the light source 14 and the display area 16 is not overlapped with the non-light-conducting area B, in this case, The size of the light guide panel 13 also becomes larger than the size of the display area 16. When the size of the light guide panel 13 becomes large, the utilization efficiency of the light guide panel 13 is deteriorated, and the work of assembling a mobile device (especially a small mobile device) becomes difficult.

(Modified example of a planar light-emitting device)

In order to improve the unevenness of the light distribution as described above, a planar light-emitting device which is processed on the light incident end surface of the light guide panel is proposed. Figures 4 and 5 show an example of such an improvement. Fig. 4 is a schematic plan view showing a modified example of the planar light-emitting device. Fig. 5 is a schematic cross-sectional view showing the modified example, and is a cross-sectional view taken along line 4 of the line segment corresponding to the X-X line of Fig. 1.

In this modified example, as shown in FIG. 4, a part of the light incident end surface 15 opposed to the light source 14 is curved in an arc shape when viewed from a direction perpendicular to the surface of the light guide panel 13. Concave portion 18. When the arc-shaped concave portion 18 is provided on the light incident end surface 15 at a position opposed to the light source 14, the change in the traveling direction of the light before and after entering the light guide panel 13 and the flat light entering the end surface The case of 15 is relatively small, so that the spread of light in the light guide panel 13 is widened. Therefore, the area of the region B where the light guiding light is not performed can be reduced.

However, according to the modified example, as shown in FIG. 5, the gap between the light emitting surface of the light source 14 and the light incident end surface 15 of the light guide panel 13 is increased by the concave portion 18, and therefore, the light source 14 is emitted from the light source 14. The light leaks light upward and becomes less likely to enter the light guide panel 13. Therefore, the amount of light that is incident from the light source 14 and incident on the light guide panel 13 is reduced, resulting in a decrease in light use efficiency. Therefore, there is a problem that the entire display region 16 is darkened.

(Patent Document 1)

Further, Patent Document 1 discloses a light-emitting panel assembly as shown in Fig. 6. In the light-emitting panel assembly of Patent Document 1, two light beams for expanding the light from the light source 23 and inputting the light output region 21 are provided on the end faces of the light output region 21 (the effective region for emitting light). The area 22 is provided with a light source 23 at one end of each of the light moving areas 22.

According to this configuration, as shown by the two-dot chain line in Fig. 6, the length of the light moving region 22 can be shortened as compared with the case of the one light moving region 24 and one light source 25. However, with only one of the light sources 23, the light cannot be transmitted in the area circled by the broken line in Fig. 6, so that the area is darkened. Therefore, two light sources 23 are required (along with the light output area 21) If the width is increased, more light sources are required, and therefore, there is a problem in that the manufacturing cost and the power consumption increase.

Prior art Patent literature

Patent Document 1 Japanese Patent Application Publication No. 2002-538577 (Fig. 7)

The present invention has been made in view of such technical problems, and an object thereof is to provide an aspect in which an effective region can be enlarged by expanding the alignment of light incident thereon, and light utilization efficiency is not easily lowered, and controllability of light distribution is high. Light guide panel.

In the light guiding panel of the present invention, the light of the light source is expanded into a planar shape by taking in from the end surface, and the light is passed through a diffusion pattern provided on at least one of the light emitting surface and the surface facing the light. a light guide panel configured to transmit or illuminate light from a predetermined area of the light exit surface to the outside, and is characterized by: a region near the region where the light of the light source enters the end surface, and the light exit surface And a light distribution control pattern for extending an alignment direction of the light for guiding light is provided on at least one of the faces facing the light.

The light guiding panel of the present invention is disposed in the vicinity of a region from which the light from the light source is incident, and is provided on at least one of the light emitting surface and the surface facing the light emitting surface to expand the alignment of the light for guiding the light. Since the light distribution control pattern reflects a part of the light that is incident from the light source into the light guide panel by the light distribution control pattern, the range of light guided in the light guide panel can be expanded. Thereby, the light can be sent to the corners or edges of the light guide panel to be illuminated, and the display area or the effective area provided with the diffusion pattern can be brightly illuminated as a whole. Moreover, since it is not necessary to separate the display area or the like from the light source, it is not necessary to increase the light guide panel. In addition, since it is not necessary to increase the number of light sources, cost and power consumption can be suppressed.

An embodiment of the light guiding panel of the present invention is characterized in that: a plurality of the light distribution control patterns are arranged in a direction to distribute light reflected by the pattern, and are perpendicular to the direction The axis of the light exit surface is arranged in an inclined shape. According to this embodiment, by changing the light distribution control pattern, the direction of the light reflected by the light distribution control pattern can be changed, and by adjusting the inclination (angle), the traveling direction of the reflected light can be controlled.

In particular, when viewed from a direction perpendicular to the light exit surface, the region on one side and the other side in the center axis of the light distribution distributed through the light incident from the light source are The light distribution control patterns are inclined toward each other in opposite directions, and the reflected light can be respectively bent outward, thereby expanding the light distribution in the light guide panel.

Further, in this embodiment, when viewed from a direction perpendicular to the light exit surface, the light distribution control pattern is arranged in line symmetry with respect to a central axis of the light distribution of the light incident from the light source. The light distribution of the light guide panel is equally extended left and right.

Further, in this embodiment, when viewed from a direction perpendicular to the light exit surface, the light distribution control pattern is disposed at a large density in a region where the amount of light emitted from the light source is large, and the amount of light is small. The light distribution control pattern is disposed at a small density in the area, whereby the brightness distribution of the light guide panel can be made uniform, and unevenness in brightness can be reduced.

Another embodiment of the light guiding panel of the present invention is characterized in that the light distribution control pattern is a triangular-shaped concave portion provided on at least one of the light exiting surface and the surface facing the light emitting surface. . According to this embodiment, the incident light can be reflected by the inclined surface (biased reflecting surface) located on the far side of the end surface (light incident end surface) among the respective surfaces of the light distribution control pattern, and the light guide can be made at this time. The light direction changes without being emitted from the light exit surface, and further travels inside the light guide panel.

In addition, in this embodiment, when the critical angle of the constituent resin of the light guide panel (the critical angle of total reflection) is θc [°], if the light distribution control pattern is located farther from the end surface, When the inclination angle of the inclined surface is less than 90°-θc (for example, when the constituent resin of the light guide panel is a polycarbonate resin, the inclination angle of the inclined surface of the light distribution control pattern located farther from the end surface is made smaller than 51°), light can be easily leaked from the light distribution control pattern to the outside, and the amount of light loss can be reduced.

The planar light-emitting device of the present invention is composed of a light source and a light-guiding panel, and is configured to take light from the light source into the light-guiding panel from the end surface of the light-guiding panel and expand into a planar shape. a diffusing pattern on at least one of a light exit surface of the light guide panel and a surface facing the light emitting surface transmits or reflects light, and emits light from a predetermined area of the light exit surface toward the outside of the light guide panel The planar light-emitting device is characterized in that: in a region near the light source, at least one of the light exiting surface of the light guiding panel and the surface facing the light emitting surface is provided for guiding light The light distribution control pattern of the light distribution in the light panel is expanded.

The planar light-emitting device of the present invention is disposed in the vicinity of a region from which the light from the light source enters, and is provided with at least one of a light exiting surface and a surface facing the light emitting surface to expand the light guiding light. Since the light distribution control pattern is in the direction, a portion of the light that is incident from the light source into the light guide panel can be reflected by the light distribution control pattern, thereby expanding the range of light guided in the light guide panel. Thereby, the light can be sent to the corners or edges of the light guide panel to be illuminated, and the display area or the effective area provided with the diffusion pattern can be brightly illuminated as a whole. Moreover, since it is not necessary to separate the display area or the like from the light source, it is not necessary to increase the light guide panel. In addition, since it is not necessary to increase the number of light sources, cost and power consumption can be suppressed.

An embodiment of the planar light-emitting device of the present invention is characterized in that, in a region where the light distribution control pattern is provided, the light exit surface of the light guide panel and the light emitting surface face each other Adhere to the reflective sheet on at least one side. According to this embodiment, when a portion of the light reflected by the light distribution control pattern travels in a direction substantially perpendicular to the light exit surface and is to leak light from the light guide panel toward the outside, the light can be reflected by the reflection sheet and returned. Light loss can be reduced in the light guide panel. Further, when the reflection sheet is adhered to the light guide panel with an adhesive or the like, the light is scattered by the adhesive, so that the effect of expanding the light distribution can be further enhanced.

In addition, in the embodiment, when the reflection sheet is further covered by the gap portion between the light guide panel and the light source, the reflection sheet can be emitted in a direction away from the end surface of the light guide panel. It becomes a light reflection of a useless light source, and this light is incident on the light guide panel, thereby improving light utilization efficiency and improving the brightness of the light guide panel.

In addition, the means for solving the problem of the present invention has a feature in which the above-described constituent elements are appropriately combined, and the present invention can be variously changed in accordance with the combination of the above-described constituent elements.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the embodiments described below, and various modifications and changes can be made without departing from the spirit and scope of the invention.

(First embodiment)

The light guiding panel of the present invention is used in a planar light emitting device. In the planar light-emitting device, light emitted from a light source is introduced into a light guide plate, and light incident on the light guide plate is expanded into a planar shape and emitted from a predetermined region of the light exit surface. Such a planar light-emitting device can be incorporated into a mobile device such as a mobile phone, and used for illumination or display.

Fig. 7 is a plan view schematically showing the planar light-emitting device 31 according to the first embodiment of the present invention, showing a state in which light is emitted. Fig. 8 is a cross-sectional view taken along the line Y-Y in Fig. 7. As shown in FIGS. 7 and 8, in the planar light-emitting device 31, the light guide panel 33 is placed on the surface of the substrate 32 so as to overlap the light incident end surface 35 of the light guide panel 33. A light source 34 is mounted on the substrate 32.

The light source 34 is a so-called point light source having a smaller width than the light incident end surface 35, and does not include a cold cathode ray tube or the like having a width (length) equal to the width of the light incident end surface 35. The light source 34 generally used is an LED light source, and one or a plurality of LED wafers 34a are sealed in a transparent encapsulating resin, and all of them are covered with a white resin except for the front surface (light emitting surface) of the transparent encapsulating resin. When the LED chip 34a is lit, white light or colored light is emitted from the light emitting surface in a substantially Langer distribution. The light source 34 faces the light incident end surface 35 with a small gap or abuts against the light incident end surface 35. The light radiated from the light source 34 enters the light guide panel 33 from a region (light incident region 39) facing the light source 34 before the light incident end surface 35.

The light guide panel 33 is formed into a rectangular plate shape or a sheet shape from a light transmissive resin having a large refractive index, for example, a polycarbonate resin, an acrylic resin, or a polymethyl methacrylate resin (PMMA). A plurality of diffusion patterns 37 and a light distribution control pattern 38 are respectively disposed on the back surface of the light guide panel 33. Further, a light-reflecting layer may be formed by applying a white paint or a white resin or a metal thin film to a region of the surface of the substrate 32 that faces the back surface of the light guide panel 33.

The diffusion pattern 37 emits light from the surface (light exit surface 40) of the light guide panel 33 by reflecting or totally reflecting the light guided in the light guide panel 33. The diffusion pattern 37 may be provided in substantially the entire area of the effective area of the light guide panel 33, or may be provided only in the display area 36 for displaying characters, marks, patterns, and the like required. When the diffusion pattern 37 is provided over substantially the entire area of the effective area, the entire effective area of the light exit surface 40 emits light. Therefore, the planar light-emitting device 31 can be used for illumination such as a backlight. Further, in the case where the diffusion pattern 37 is provided only in the predetermined display area 36, it can be used for display. In the example of the figure, the main display is for display, and the display area 36 displays the character "A". Hereinafter, the case for display will be described, but it is not intended to exclude the case for use in illumination.

The diffusion pattern 37 is a concave portion formed on the back surface of the light guide panel 33. As shown in Fig. 9(A), one diffusion pattern 37 has a triangular shape. The reflecting surface 37a is a surface for totally reflecting light guided in the light guiding panel 33, and is incident on the end surface 35 side toward the light. As shown in Fig. 9(B), the inclination angle α of the reflection surface 37a is set such that the total reflection light is directed toward the outside from the light exit surface 40 in a direction substantially perpendicular to the light exit surface 40, and the inclination angle is set. α is approximately 45°. The inclination angle β of the back surface 37b of the diffusion pattern 37 is 90° or slightly smaller than 90°. The light that is totally reflected by the reflecting surface 37a and passes through the reflecting surface 37a passes through the back surface 37b and is incident into the light guiding panel 33 to be reused.

Further, the diffusion pattern 37 may be formed into various shapes other than the shape shown in FIG. The diffusion pattern 37 only needs to be totally reflected by the reflection surface 37a and emitted from the light exit surface 40. Therefore, the inclination angle of the back surface 37b can be an arbitrary angle. For example, in the diffusion pattern 37 shown in Figs. 10(A) and 10(B), the inclination angle of the back surface 37b is equal to the inclination angle of the reflection surface 37a (i.e., β = α), and the cross-sectional shape thereof becomes Second equilateral triangle.

Further, the diffusion pattern 37 may be curved as a whole and the reflecting surface 37a may be curved into a concave shape or curved into a convex shape. Further, the diffusion pattern 37 may be a triangular pyramid pattern, a quadrangular pyramid (pyramidal) pattern, or a substantially conical pattern. Further, the diffusion pattern 37 may be a white light-diffusing ink or the like printed on the back surface of the light guide panel 33.

The light distribution control pattern 38 is an alignment distributor for expanding light incident on the light guide panel 33 from the light incident region 39, and is provided on the back surface of the light guide panel 33 in the vicinity of the light incident region 39. The light distribution control pattern 38 is also a concave portion formed on the back surface of the light guide panel 33. As shown in Fig. 11(A), one light distribution control pattern 38 has a triangular shape. The deflecting reflection surface 38a of the light distribution control pattern 38 is a total reflection of light incident on the light guiding panel 33, and is changed from the direction perpendicular to the light exit surface 40 to change the traveling direction of the light before and after the reflection. . The larger the inclination angle ε of the deflecting reflection surface 38a, the greater the effect of changing the alignment of the reflected light, but the light does not easily enter the deflecting surface 38a.

The surface or the back surface of the light guiding panel 33 (not the portion of the light distribution control pattern 38) that is guided by the light in the light guiding panel 33 is incident at an incident angle smaller than the critical angle θc [°] of the total reflection. Light leaks from the surface or the back surface of the light guide panel 33 to the outside. Thereby, the light-expanding range of the light guided in the light guide panel 33 is in a cross section perpendicular to the surface of the light guide panel 33 and the light incident end surface 35, and is oriented perpendicular to the direction in which the light is incident on the end surface 35. The front side and the back side are respectively "90° - critical angle θc". Therefore, when the inclination angle ε of the deflecting reflection surface 38a of the light distribution control pattern 38 is larger than "90° - the critical angle θc", the light is completely prevented from entering the deflecting surface 38a, so that the light is incident. The total reflection is performed on the deflecting surface 38a, and the inclination angle ε of the deflecting surface 38a needs to be "90°-critical angle θc" or less. For example, when the refractive index of the light guide panel 33 is 1.59 (the refractive index of the polycarbonate resin), the critical angle θc is 39°, so that the light guided to the light guide panel 33 is developed toward the back side. The range becomes 51° (=90°-39°). Thereby, when the inclination angle ε of the deflecting reflection surface 38a is 51° or less, the light guided in the light guiding panel 33 can be totally reflected. Further, when the refractive index of the light guide panel 33 is 1.49 (the refractive index of the acrylic resin), the critical angle θc is 42°, so that the development range of the light guided to the light guide panel 33 toward the back side becomes 48° (=90°-42°). Thereby, when the inclination angle ε of the deflecting reflection surface 38a is 48° or less, the light guided in the light guide panel 33 can be totally reflected. On the other hand, when the inclination angle ε of the deflecting reflection surface 38a becomes small, the light is easily irradiated onto the deflecting reflection surface 38a, but the effect corresponding to the partial deviation of the light is reduced correspondingly, so when the inclination angle ε When it is too small, it will cause a decrease in efficiency. Thereby, the value of the optimum tilt angle ε is determined by experiment or by simulation.

The front surface 38b of the light distribution control pattern 38 faces the side of the light incident end face 35, and the inclination angle γ of the front surface 38b is 90° or slightly smaller than 90°. When the height of the front surface 38b is high, light is easily irradiated to the front surface 38b, so that light passes through the front surface 38b and leaks light toward the outer surface of the light guide panel 33, resulting in loss of light amount. Therefore, it is preferable that the height of the front surface 38b is low.

As shown in FIGS. 7 and 12, when viewed in a direction perpendicular to the light exit surface 40, the light distribution control pattern 38 is arranged to be line-symmetric with respect to the center axis T of the light source 34 as a center, and is relatively symmetrical with respect to the center of the light. The axis T is disposed such that the region on one side and the region on the other side are inclined toward each other. That is, in FIG. 7, in the right region of the central axis T of the light, each light distribution control pattern 38 is rotated clockwise by an angle Φ (>0) from the central axis T of the light about an axis perpendicular to the light exit surface 40. In the left region of the central axis of illumination T, each light distribution control pattern 38 is formed by a counterclockwise rotation angle Φ (>0) from the central axis of illumination T about an axis perpendicular to the light exit surface 40. Thereby, when light incident into the light guide panel 33 from the light incident region 39 is incident on the light distribution control pattern 38, or when light incident into the light guide panel 33 is reflected on the front and back surfaces of the light guide panel 33, When the light distribution control pattern 38 is incident, as shown in FIG. 13, the light totally reflected by the deflecting reflection surface 38a of the light distribution control pattern 38 on the right side is bent in the right direction, and the light distribution control pattern 38 on the left side is bent. The light that is totally reflected by the deflecting reflection surface 38a is bent in the left direction. As a result, the light distribution pattern can be extended by the light distribution control pattern 38, and the light guiding light can be performed in the region of the region B where the light guiding light is not emitted when the light distribution control pattern 38 is not provided, as shown in FIG. It is shown that the area B where light guiding is not performed becomes small. Further, light guiding light is also performed in a direction in which a large angle is formed with the central axis T of the light emission, so that the brightness in the light guiding panel 33 can be made uniform. Thereby, as shown in FIG. 7, light can be emitted throughout the display area 36.

When the normal line set on the deflecting reflection surface 38a is N, as shown in Fig. 12, when viewed from a direction perpendicular to the light exit surface 40, the inclination angle Φ of the light distribution control pattern 38 can be defined as a normal line and a light emission. The angle formed by the direction in which the central axis T is parallel. This inclination angle Φ can be determined by experiment or simulation based on the area in which the display area 36 is provided or the like.

Further, the arrangement (distribution) or density of the light distribution control pattern 38 may be determined in consideration of the light distribution of the entire light. However, since the light distribution control pattern 38 shields or hinders light that normally conducts light, when the light distribution control pattern 38 is provided in a large amount, there is a fear that the amount of light is lowered. Thereby, the light distribution control pattern 38 needs to be designed in such a manner that its shape, size, density, and the like are optimal. All the light guided in the light guide panel 33 is not necessarily reflected by the diffusion pattern 37 and is used for the light-emitting display. Therefore, even if the light distribution control pattern 38 is designed in an optimized manner, even if the light is subjected to light distribution The obstruction of the control pattern 38 does not cause a large efficiency reduction to the planar light-emitting device 31. Rather, it is expanded into a wide range of light, which is more utilized in the display of the display area 36, thereby improving the efficiency of light utilization and improving the overall brightness efficiency.

Further, the light distribution control pattern 38 is not limited to the flat deflection surface 38a shown in Fig. 11, and as shown in Fig. 14(A), the deflection surface 38a may be a convex curved surface, or, as in the 14th. As shown in (B), the deflecting surface 38a may also have a concave curved surface. In the light distribution control pattern 38 in which the deflecting reflection surface 38a has a convex curved surface, the light reflected by the deflecting surface 38a can be diffused, and in the light distribution control pattern 38 in which the deflecting surface 38a has a concave curved surface, the bias can be biased. The light reflected by the reflecting surface 38a has condensing properties. Further, the light distribution control pattern 38 in which the deflecting reflection surface 38a is flat, the light distribution control pattern 38 in which the deflecting reflection surface 38a has a convex curved surface, and the light distribution control pattern 38 in which the deflecting reflection surface 38a has a concave curved surface may be used in combination.

Next, the result obtained by verifying the light distribution control pattern 38 by simulation will be described. Figures 15 and 16 show models for the simulated planar illumination device. As shown in Fig. 16, the light source 34 is disposed such that the width c of the light radiating surface is 1.8 mm and the gap between the light incident end faces 35 is f = 0.2 mm. The light source 34 is an LED light source that emits white light by a combination of a blue LED and a (yellow) phosphor, and emits light of a Langer distribution from the light source 34. The light distribution control pattern 38 is arranged in a region of a vertical direction a = 1 mm and a horizontal width b = 2 mm, and is disposed at intervals of 0.1 mm (intercenter distance). The light distribution control pattern 38 is arranged in line symmetry with respect to the central axis T of the light emission, and the inclination angle of the light distribution control pattern 38 is also line symmetrical with respect to the central axis T of the light emission. One light distribution control pattern 38 has a length of d = 30 μm and a width of e = 106 μm in plan view, and an inclination angle ε of the deflecting reflection surface 38a is set to 45°. In addition, any of the light distribution control patterns 38 are inclined at an equal angle Φ = 38°.

The light guide panel 33 is prepared such that the diffusion pattern 37 is not provided on the back surface, and the light distribution control pattern 38 is not provided, and only the light distribution control pattern 38 is provided. Further, the refractive index of the light guiding panel 33 is 1.59 (the refractive index of the polycarbonate resin). Since none of the light guide panels 33 has the diffusion pattern 37, the light guided in the light guide panel 33 is not emitted from the light exit surface 40, but is incident on the end surface on the opposite side of the end surface 35. As shown in Figs. 15(A) and 15(B), the light amount measuring device 41 is disposed along the end surface opposite to the light incident end surface 35 of the light guiding panel 33, by measuring the positions of the incident light amount measuring device 41. The intensity of light received by the light is determined by the intensity of the light in all directions (light distribution). As shown in Fig. 15(A), the light amount measuring device 41 is disposed in a direction parallel to the central axis T of the light emission (θ = 0°), and can be in the light distribution direction θ = -65° to θ = -65 Measurements were made within the range of °.

Fig. 17 is a view showing the intensity of light guided by the light amount measuring device 41 to the light guided to the respective sides in the light guiding panel 33 by the light guiding panel 33 which is provided with neither the diffusion pattern 37 nor the light distribution control pattern 38 on the back surface. (Luminescence intensity) The result of measurement was performed. The horizontal axis of Fig. 17 indicates the angle (light distribution direction θ) with respect to the central axis T of the light emission, and the vertical axis indicates the luminous intensity of each light distribution direction θ. As can be seen from the graph of Fig. 17, when the light distribution control pattern 38 is not provided, the light intensity of the front side of the light source 34 is the largest in the light guide panel 33, and the light is emitted from the light distribution direction θ = ±15°. The intensity is lowered, and the luminous intensity is close to zero in the vicinity of the light distribution direction θ=±39° which is equal to the critical angle. Further, in the light distribution direction (|θ|>39°) larger than the critical angle, the light emission intensity does not become zero, and it is considered to be a factor such as scattering or blooming of light in the light guide panel 33.

Fig. 18 is a view showing the rate of change in luminance when the light guide panel 33 provided with the light distribution control pattern 38 on the back surface is used. The luminance change rate in the light distribution direction θ is (the light emission luminance in the light distribution direction θ when the light guide panel 33 of the light distribution control pattern 38 is provided) ÷ (when the light guide panel 33 having the light distribution control pattern 38 is used) The brightness of the same light distribution direction θ). Fig. 18 shows the light distribution direction (|θ| < Φ = 38°) which is smaller than the inclination angle Φ of the light distribution control pattern 38, and the luminance change rate is about 1, but at the inclination angle Φ of the light distribution control pattern 38. The large light distribution direction (|θ|>Φ=38°), the brightness change rate becomes much larger than 1. From this, it is understood that by providing the light distribution control pattern 38, the light distribution can be expanded, and light guiding can be performed in a light distribution direction larger than the inclination angle Φ of the light distribution control pattern 38.

(Second embodiment)

Next, the planar light-emitting device 51 according to the second embodiment of the present invention will be described. However, the same components as those of the first embodiment will not be described. Fig. 19 is a plan view schematically showing the planar light-emitting device 51 of the second embodiment. In addition, Fig. 20(A) is a schematic cross-sectional view of the planar light-emitting device of the second embodiment, and Fig. 20(B) is a partially enlarged view of the planar light-emitting device of Fig. 20(A).

In the planar light-emitting device of the first embodiment, the planar light-emitting device 51 of the second embodiment is further adhered to the upper surface of the light source 34 and the light guide panel 33 so as to cover the light source 34 and the light distribution control pattern forming region. Light shielding tape 52. The light-shielding tape 52 is a reflection sheet 54 composed of a white sheet or a reflective sheet that reflects light in a lower area layer of the black sheet 53 that absorbs light, and a double-sided adhesive tape 55 is adhered to the lower surface of the reflection sheet 54. The light shielding tape 52 is adhered to the upper surface of the light source 34 and the light guide panel 33 by the double-sided adhesive tape 55.

According to the planar light-emitting device 51, the light that is to be leaked upward from the gap between the light source 34 and the light incident end surface 35 is not reflected by the radiation sheet 54 by directly entering the light incident end surface 35 from the light source 34. This light can be incident into the light guide panel 33 from the light incident end surface 35. Thereby, it is possible to reduce the loss of light caused by the reason of not reducing the light use efficiency by entering the light guide panel 33, and it is possible to improve the luminance efficiency of the planar light-emitting device 51.

Further, since the reflection sheet 54 is adhered to the position opposite to the light distribution control pattern 38, leakage of light reflected by the light distribution control pattern 38 from the light exit surface 40 can be prevented, and the amount of light can be reduced.

Further, the light incident on the light guide panel 33 is scattered and reflected by the reflection sheet 54 and the double-sided adhesive tape 55 on the upper surface of the light guide panel 33, so that the light distribution can be further uniformized.

Further, the light distribution control pattern 38 may have various shapes in addition to the shapes shown in Figs. 11 and 14. For example, as in the light distribution control pattern 38 shown in Figs. 21(A) and (B), the inclination angle of the front surface 38b is equal to the inclination angle of the deflecting reflection surface 38a (i.e., γ = ε), and the sectional shape. It is a second equilateral triangle. In the light distribution control pattern 38 having a two-sided triangular cross section, as shown in Fig. 22(A), the entire deflection can be made to bend the deflecting surface 38a into a convex curved surface, as shown in Fig. 22(B). It is also possible to bend the whole and bend the deflecting surface 38a into a concave curved shape. When the deflecting reflection surface 38a is curved into a convex curved surface, the light reflected by the deflecting reflection surface 38a can be further diffused. Further, when the deflecting reflection surface 38a is curved into a concave curved shape, the light reflected by the deflecting reflection surface 38a can be collected.

Further, as shown in the 23rd (A) to (D), the light distribution control pattern 38 may be a zigzag pattern, a triangular pyramid pattern, a quadrangular pyramid (pyramidal) pattern, a substantially conical pattern, or the like. Further, these various light distribution control patterns 38 may be mixed.

(Other implementations)

The light distribution control pattern 38 can be arranged in various ways in addition to the description of the first embodiment, whereby the light distribution can be controlled more precisely. Moreover, in the 24th to 28th drawings, the light distribution control pattern provided on the back surface of the light guide panel 33 is displayed on the surface of the light guide panel 33. On the other hand, the illustration of the diffusion pattern 37 is omitted in the drawing.

Generally, as in the planar light-emitting device 61 of Fig. 24(A), the light source 34 and the center of the light guide panel 33 are arranged to face each other, and the light distribution control pattern 38 is also opposed to the central axis of the light source 34. It is preferable to provide bilaterally symmetrically so that light is uniformly aligned on the right and left sides of the light guide panel 33. However, in the case where the display region 36 is asymmetrical left-right or at a position deviated from the central portion of the light guide panel 33, the display device 36 may be deflected as in the planar light-emitting device 62 of Fig. 24(B). The light source 34 and the light distribution control pattern 38 are disposed at the center of the light panel 33, and the light distribution control pattern 38 is disposed symmetrically with respect to the light emission center axis of the light source 34.

Further, the light distribution control pattern 38 may be uniformly distributed in the light distribution control pattern formation region like the planar light-emitting device 63 of Fig. 25(A), but may be illuminated like the surface of Fig. 25(B). The device 64 is randomly distributed as such.

Further, the light distribution control pattern 38 may be formed in a region where the amount of light guided from the light source 34 is large as in the planar light-emitting device 65 of Fig. 26 (i.e., at a small angle with the central axis of the light source 34). In the region, the density of the light distribution control pattern 38 is increased, and the density of the light distribution control pattern 38 is reduced in a region where the amount of light is small (that is, a region where a large angle is formed with the central axis of the light source 34). According to this configuration, light in a direction in which the amount of light is large can be diffused in a wider range, and light diffusion in a direction in which the amount of light is small can be reduced. Therefore, the amount of light can be made uniform in the entire light guide panel 33.

Further, the light distribution control pattern 38 may have a different inclination angle (Φ) depending on the position as in the planar light-emitting device 66 of Fig. 27.

Further, the light distribution control pattern 38 may also have a mixed inclination angle on one side of the light-emitting central axis of the light source 34, like the planar light-emitting device 67 of the 28th (A) diagram and the planar light-emitting device 68 of the 28th (B) diagram. Different people. Specifically, in the planar light-emitting device 67 shown in Fig. 28(A), the planar light-emitting device shown in Fig. 28(B) is reversed in the direction in which the light distribution control pattern 38 is rotated. In 68, the rotation direction of the light distribution control pattern 38 is reversed in each column.

Further, the light distribution control pattern 38 may not be formed on the surface opposite to the light exit surface 40 of the light guide panel 33, but may be formed on the same surface as the light exit surface 40. Similarly, the diffusion pattern 37 may be formed on the light exit surface 40 such that light diffused by the diffusion pattern 37 to be transmitted and emitted from the light exit surface 40.

In the present invention, the light distribution distribution in the light guide panel 33 can be precisely controlled by the combination of the light distribution control patterns 38 or the light distribution control patterns 38.

Further, when the width of the light guide panel 33 is wide, a plurality of light sources 34 may be used, and the light distribution control pattern 38 may be disposed in the vicinity of each of the light sources 34.

31, 51, 61 ~ 68. . . Planar illuminating device

32. . . Substrate

33. . . Light guide panel

34. . . light source

34a. . . LED chip

35. . . Light injection into the end face

36. . . Display area

37. . . Diffusion pattern

37a. . . Reflective surface

37b. . . back

38. . . Light control pattern

38a. . . Biased surface

38b. . . front

39. . . Light injection area

40. . . Light exit surface

41. . . Light quantity measuring device

52. . . Shading tape

53. . . Black sheet

54. . . A reflective sheet

55. . . Double-sided adhesive tape

B. . . Area where light is not guided

T. . . Luminous central axis

Fig. 1 is a plan view schematically showing a conventional planar light-emitting device.

Fig. 2 is a schematic cross-sectional view taken along the line X-X in Fig. 1.

Figure 3 is a plan view showing the planar light-emitting device after the light source has been separated from the display area.

Fig. 4 is a plan view showing a modified example of the surface light source device.

Fig. 5 is a schematic cross-sectional view showing the surface light source device of Fig. 4.

Fig. 6 is an explanatory view of a light-emitting panel module disclosed in Patent Document 1.

Fig. 7 is a plan view schematically showing a planar light-emitting device according to a first embodiment of the present invention.

Fig. 8 is a schematic cross-sectional view showing the planar light-emitting device of the first embodiment.

Figure 9(A) is a perspective view of a diffusion pattern. Fig. 9(B) is a cross-sectional view of the diffusion pattern provided on the back surface of the light guide panel.

Figure 10(A) is a perspective view of a diffusion pattern of different shapes. Fig. 10(B) is a cross-sectional view of the diffusion pattern provided on the back surface of the light guide panel.

Figure 11(A) is a perspective view of a light distribution control pattern. Fig. 11(B) is a cross-sectional view of the light distribution control pattern provided on the back surface of the light guide panel.

Fig. 12 is an explanatory diagram for explaining the inclination of the light distribution control pattern.

Fig. 13 is an explanatory diagram for explaining the action of the light distribution control pattern.

Figures 14(A) and (B) are perspective views of light distribution control patterns having different shapes, respectively.

Fig. 15(A) is a plan view of the planar light-emitting device for simulation. Fig. 15(B) is a schematic cross-sectional view showing the planar light-emitting device of Fig. 15(A).

Fig. 16 is a plan view showing a light distribution control pattern forming region of the planar light-emitting device of Fig. 15(A).

Fig. 17 is a view showing the result of measuring the light distribution in the light guide panel having no pattern on the back surface.

Fig. 18 is a view showing the rate of change in intensity when the light distribution is controlled using the light distribution control pattern.

Fig. 19 is a plan view schematically showing a planar light-emitting device according to a second embodiment of the present invention.

Fig. 20(A) is a schematic cross-sectional view showing a planar light-emitting device of a second embodiment. Fig. 20(B) is a partially enlarged view of the planar light-emitting device of Fig. 20(A).

Fig. 21(A) is a perspective view of a light distribution control pattern of different shapes. Fig. 21(B) is a cross-sectional view of the light distribution control pattern 38 provided on the back surface of the light guide panel.

Figures 22(A) and (B) are perspective views of various light distribution control patterns having other shapes.

23(A) to (D) are perspective views of various light distribution control patterns having other shapes.

Fig. 24(A) is a schematic plan view showing a light distribution control pattern disposed at the center of the light guide panel. Fig. 24(B) is a schematic plan view showing a light distribution control pattern disposed at a position deviated from the center of the light guide panel.

Fig. 25(A) is a schematic plan view showing a light distribution control pattern which is regularly distributed. Fig. 25(B) is a schematic plan view showing a randomly distributed light distribution control pattern.

Fig. 26 is a schematic plan view showing a light distribution control pattern in which a distribution pattern is changed in a region where the amount of light is large and a region where the amount of light is small.

Fig. 27 is a schematic plan view showing a light distribution control pattern having different inclination angles.

The 28th (A) and (B) are schematic plan views showing an example in which the rotation direction of the light distribution control pattern is reversed for each row or column.

31. . . Planar illuminating device

32. . . Substrate

33. . . Light guide panel

34. . . light source

35. . . Light injection into the end face

36. . . Display area

37. . . Diffusion pattern

38. . . Light control pattern

39. . . Light injection area

B. . . Area where light is not guided

Claims (9)

A light guiding panel is configured to take in light from a light source and expand into a planar shape, and penetrate the light through a diffusion pattern disposed on at least one of a light exiting surface and a surface facing the light emitting surface Or a light-conducting panel that reflects light from a predetermined area of the light exit surface to the outside, and is characterized in that: near the region where the light of the light source enters, the light exiting surface and the light exiting the light-emitting surface a plurality of light distribution control patterns having a meandering shape for expanding an alignment direction of light to be guided light, at least one of the faces facing the surface, the light distribution control pattern having an inclined surface, a normal of the inclined surface The direction is non-parallel with respect to the light emitting surface and the surface of the light emitting surface facing the light distribution control pattern, and the light distribution control pattern is respectively directed to the light to be reflected by the pattern The direction of the light distribution is arranged to be inclined around an axis perpendicular to the light exit surface, and is viewed from a central axis of the light distribution distributed through the light source from the direction perpendicular to the light exit surface. One side of the area and the other side Field, the light distribution pattern control system toward the direction inclined opposite to each other. The light guide panel of claim 1, wherein the light distribution control pattern is line symmetrical with respect to a central axis of the light distribution of the light incident from the light source when viewed from a direction perpendicular to the light exit surface. Ground configuration. For example, the light guide panel of claim 1 of the patent scope, wherein the light beam is emitted from When viewed in a direction perpendicular to the vertical direction, the light distribution control pattern is arranged such that the distance between the light distribution control patterns is shortened in a region where the amount of light of the light emitted from the light source is large, and in a region where the amount of light is small The manner in which the distance between the light distribution control patterns is elongated is configured. The light guide panel of claim 1, wherein the light distribution control pattern is a triangular-shaped concave portion provided on at least one of the light exit surface and the surface facing the light. The light guide panel of claim 4, wherein when the critical angle of the constituent resin is θc [°], the oblique angle of the inclined surface of the light distribution control pattern located farther from the end surface is less than 90° -θc. The light guide panel of claim 5, wherein the constituent resin is a polycarbonate resin, and the inclined angle of the inclined surface of the light distribution control pattern located farther from the end surface is less than 51°. A planar light-emitting device is composed of a light source and a light-guiding panel, and is configured to take in light of the light source from an end surface of the light-guiding panel and expand into a planar shape, and the light is emitted from the light-guiding panel. a planar light-emitting device that emits light from a predetermined area of the light-emitting surface toward the outside of the light-guiding panel, and a diffusing pattern on at least one of the surfaces facing the light-emitting surface that transmits or reflects light The invention is characterized in that: in a region near the light source, at least one of the light exit surface of the light guide panel and the surface facing the light exit surface is provided with an alignment for expanding light guided in the light guide panel a plurality of light distribution control patterns distributed in a meandering manner, the light distribution control pattern having an inclined surface, the normal direction of the inclined surface being relative to the light exiting surface and The surface of the light emitting surface facing the light distribution control pattern is non-parallel, and the light distribution control pattern is respectively oriented toward the light distribution to be reflected by the pattern to surround the perpendicular The axis of the light exit surface is arranged obliquely, and when viewed from a direction perpendicular to the light exit surface, a region on one side and a region on the other side are provided on a central axis of the light distribution distributed through the light incident from the light source. The light distribution control patterns are inclined toward each other in opposite directions. The planar light-emitting device of claim 7, wherein in the region where the light distribution control pattern is provided, at least one of the light exit surface of the light guide panel and the surface facing the light exiting surface Paste the reflective sheet. The planar light-emitting device of claim 8, wherein the reflective sheet further covers a gap portion between the light guide panel and the light source.