JP2005285620A - Illumination device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an illumination device in which a brightness reduction part in the vicinity of a light emitting face end part can be suppressed. <P>SOLUTION: This illumination device is constituted so that in a direct backlight 1, a lens sheet 17 is arranged on a reflecting face 16a of a parallel side inner wall side face 11c. By this, the brightness in the vicinity of the light emitting face 12a end part can be enhanced, and occurrence of the brightness reduction part can be suppressed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a lighting device used for a backlight of a liquid crystal display device.

2. Description of the Related Art Conventionally, as a lighting device used for a backlight of a liquid crystal display device or the like, there is a direct type backlight. This direct type backlight has a box frame with an opening on one side, a diffusion plate as a planar diffusion member to be a light emitting surface arranged on the opening side, and a light source behind the diffusion plate. The inner wall bottom surface and the inner wall side surface of the frame are configured to be reflective surfaces that reflect light from the light source toward the diffuser plate.
In such an illumination device, when the brightness of the reflected light from the side reflecting surface of the inner wall of the frame is low, the brightness near the end of the light emitting surface decreases, or dark lines where the low brightness portion appears linearly on the light emitting surface, etc. In some cases, a reduced luminance portion appears near the edge of the light emitting surface. Thus, if there is a luminance reduction portion at the end of the light emitting surface of the lighting device, a luminance difference is produced on the screen of the liquid crystal display device, and the screen quality is impaired. For this reason, in this kind of illuminating device, the thing with the high luminous quality in which luminance distribution is uniform over the whole light emission surface is requested | required.
Conventionally, as a reflective surface behind the light source of the lighting device, (1) a metallic glossy sheet having a glossy surface obtained by vapor deposition of metal, (2) a reflection plate formed into a corrugated shape or a chevron, (3) diffuse reflection Sheets and the like have been used (see, for example, Patent Documents 1 and 2).

JP-A-5-61043 (2nd page) JP-A-6-250178 (page 2)

  However, in the illumination device using the metallic glossy sheet of (1) above, the brightness of the reflected light from the side reflecting surface can be increased, but the metallic glossy surface regularly reflects the light from the light source. It was difficult to eliminate the brightness reduction portion. In addition, when the reflector of (2) is used, the shape of the reflector is complicated, and it is difficult to set an optimum shape that can eliminate the luminance reduction portion near the light emitting surface end, and the reflection is further reduced. There are problems that processing is required for the plate and that the positional relationship between the light source and the shape of the reflecting plate needs to be set with high accuracy. In addition, when the diffuse reflection sheet of (3) is used, since the light from the light source is diffusely reflected, the brightness of the reflected light on the side reflection surface is greatly reduced, and a brightness reduction portion near the end of the light emitting surface appears. Could not be suppressed.

  This invention is made | formed in view of such a situation, and it aims at provision of the illuminating device which can suppress generation | occurrence | production of the brightness fall part in the light emission surface edge part vicinity.

  The present invention provides a diffuser plate serving as a light emitting surface, a light source disposed behind the diffuser plate, and disposed opposite the diffuser plate behind the light source and reflects light from the light source toward the diffuser plate. In a lighting device having a bottom surface reflecting surface and a side surface reflecting surface disposed on a side portion of the bottom surface reflecting surface to reflect the light of the light source toward the diffuser plate, the lens surface is disposed on the side surface reflecting surface. A lens layer on the diffusion plate side is arranged.

  According to the illuminating device configured as described above, the lens layer is disposed on the side reflecting surface with the lens surface on the diffusion plate side, thereby increasing the luminance near the light emitting surface end portion and reducing the luminance reduction portion. The present inventor has found that generation can be suppressed. That is, the present inventor suitably reflects the light emitted from the light source toward the side reflecting surface by arranging a lens layer on the side reflecting surface, and the brightness of the reflected light by the side reflecting surface is reduced. Based on this finding, the present invention has been completed based on this finding.

In the illumination device, the light source has a straight tubular portion, a plurality of fine lens strips are provided on the lens surface of the lens layer, and the longitudinal direction of the lens strip is substantially parallel to the straight tubular portion. It is preferable that
In this case, since the lens strip of the lens layer can be arranged along the shape of the light source, the light emitted from the light source can be effectively condensed by the lens layer. Therefore, the brightness of the reflected light from the side reflecting surface can be further increased.

  In the lighting device, it is preferable that an inclination angle of the side surface reflecting surface with respect to a surface obtained by extending the bottom surface reflecting surface outward is 45 degrees or more. In this case, by arranging the lens layer on the side reflecting surface and setting the tilt angle to 45 degrees or more, the light reflected by the side reflecting surface is more reliably near the end of the diffuser plate while increasing the brightness. Can be emitted. Therefore, the brightness near the end of the light emitting surface can be effectively increased.

  Moreover, the said illuminating device WHEREIN: It is preferable that the said side surface reflection surface is a diffuse reflection surface. In this case, the side surface reflection surface can reflect the light from the light source while diffusing, so that uniform reflected light can be emitted to the diffusion plate. Therefore, the light emission quality in the lighting device can be made higher.

  In the illumination device, it is preferable that an air layer is provided between the side surface reflecting surface and the lens layer. In this case, there are fine irregularities for performing diffuse reflection on the side reflective surface that is the diffuse reflective surface, and by providing an air layer, the diffuse reflection on the diffuse reflective surface becomes effective. can do. Thereby, the brightness | luminance of the reflected light by the said side surface reflective surface can be maintained in a high state.

  In the illumination device, it is preferable that the lens layer has light resistance. In this case, even if the lens layer receives ultraviolet rays from the light source, the lens layer can be prevented from deteriorating due to its light resistance. Accordingly, it is possible to prevent the luminance, light emission quality, and the like of the lighting device from decreasing with time.

  As described above, according to the illuminating device of the present invention, by providing the lens layer on the side reflection surface, the luminance near the end of the light emitting surface is increased, and the occurrence of the luminance reduction portion appearing near the end of the light emitting surface is generated. Can be suppressed.

  Next, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, a case where the lighting device of the present invention is applied as, for example, a 10-inch direct-type backlight disposed on the back side of a liquid crystal display device will be described as an example. FIG. 1A is a cross-sectional view schematically showing the structure of a direct type backlight according to the first embodiment of the present invention. This direct type backlight 1 includes a box-shaped lower frame 11 having an opening on one side, a diffusion plate 12 as a planar diffusion member arranged so as to close the opening, and a rear side (directly below) of the diffusion plate 12. And an upper frame 20 disposed on the diffusion plate 12 via a diffusion sheet 12b disposed on the surface of the diffusion plate 12.

  As the diffusion plate 12, for example, a white or milky white plate such as polycarbonate or acrylic is used. In this embodiment, a product name “Acrylite No. 432” manufactured by Mitsubishi Rayon Co., Ltd., which is an acrylic resin plate, was used, and the plate thickness was set to 2 mm. Such a diffusion plate 12 is disposed so as to close the opening of the lower frame 11, and can diffuse and transmit light from the light source 13 disposed behind. With such a diffusion plate 12, the light from the light source 13 can be made uniform and emitted from the light emitting surface 12 a of the diffusion plate 12.

  The diffusion sheet 12b is disposed on the light emitting surface 12a of the diffusion plate 12, and further diffuses the light emitted from the light emitting surface 12a. The upper frame 20 disposed above the diffusion plate 12 is formed of, for example, an aluminum alloy, and is formed in a rectangular frame shape surrounding the lower frame 11. An edge 20a is provided at the upper end of the upper frame, and the upper frame 20 is placed on the lower frame 11 with the edge 20a abutting against the peripheral edge of the diffusion plate 12 via the diffusion sheet 12b. ing. FIG. 1B is a top plan view of FIG. As shown in this figure, the edge portion 20a forms an opening portion 20b that is opened in a substantially rectangular shape by its end portion. The opening 20b is set to substantially coincide with the opening of the lower frame 11 formed at the upper ends of the reflecting surfaces 15a and 16a, and forms an exposed surface 12c that exposes the light emitting surface 12a to the outside. .

  As shown in FIG. 1A, the direct type backlight 1 according to the present embodiment is configured such that a reflection surface 14a of an inner wall bottom surface 11a described later is disposed on the exposed surface 12c. Near the end of the surface 12c, there is a range U (shaded portion in FIG. 1B) where reflective surfaces 15a and 16a of inner wall side surfaces 11b and 11c, which will be described later, are disposed behind the surface 12c.

  FIG. 2A is a plan view of the direct backlight according to the present embodiment with the diffuser 12 removed, and FIG. 2B is a cross-sectional view taken along the line S-S in FIG. . As shown in FIG. 2, the light source 13 includes, for example, three cold-cathode tubes 13a each having a U-shaped tubular body having a diameter of 3 mm, and is attached to a connector 13b and supported by a lamp support stand (not shown). And accommodated in the lower frame 11. The cold cathode tube 13a has a straight tubular portion 13a1 in its longitudinal direction, and the straight tubular portions 13a1 are juxtaposed so as to be substantially parallel to the horizontal direction of the frame at a pitch interval of 23.5 mm. The light source 13 is connected to an inverter or the like (not shown) so that it can be turned on / off.

  The lower frame 11 is formed of, for example, an aluminum alloy, and has a rectangular bottom surface, a side surface located on the end side in the longitudinal direction of the cold cathode tube 13 a erected so as to spread from the bottom surface to the opening side, and the light source 13. It has a side surface substantially parallel to the longitudinal direction, and is formed in a shape in which one surface is open. Referring also to FIG. 1 and FIG. 2B, the inner wall bottom surface 11a of the lower frame 11 and a side surface 11b (hereinafter referred to as an end portion inner wall side surface 11b) which is an inner wall side surface located on the end side in the longitudinal direction of the cold cathode tube 13a. ) And the side surface 11c (hereinafter also referred to as a parallel side inner wall side surface 11c) which is a side surface substantially parallel to the longitudinal direction of the cold cathode tube 13a, respectively, are diffuse reflection sheets 14, 15, and 16 respectively. The surfaces of these diffuse reflection sheets are reflective surfaces 14a, 15a, and 16a that reflect light from the light source 13, respectively. As this diffuse reflection sheet, for example, a product name “E60V” manufactured by Toray Industries, Inc., which is a white diffuse reflection sheet, was used.

  A lens sheet 17 as a lens layer is disposed on the reflection surface 16 a of the diffuse reflection sheet 16 affixed to the parallel inner wall side surface 11 c of the lower frame 11. The lens sheet 17 is a plate-like body formed of a transparent resin such as acrylic or polycarbonate. Specifically, in this embodiment, a trade name “BEFII90 / 50” manufactured by Sumitomo 3M Co., Ltd. is used. FIG. 3 is an enlarged view schematically showing a cross section of a portion surrounded by a broken line A in FIG. As shown in FIG. 3, the lens sheet 17 constitutes a prism lens sheet having a lens surface 17b provided with a plurality of lens sections 17a having a fine triangular cross section at an equal pitch in one direction. In the present embodiment, the lens sheet 17 formed on the lens strip having a triangular cross section is used as the lens layer. However, for example, a lens sheet having a lens strip having a semicircular cross section may be used.

  The lens sheet 17 is fixed by adhering a part thereof to the reflecting surface 16a using an adhesive. At this time, as shown in FIG. 3, a pressure-sensitive adhesive layer 18 made of a pressure-sensitive adhesive interposed between the lens sheet 17 and the reflecting surface 16a adheres a part between them. A plurality of such adhesive layers 18 are provided on the surface of the reflecting surface 16a, and a minute air layer is formed between the lens sheet 17 and the reflecting surface 16a. The pressure-sensitive adhesive layer 18 is preferably substantially transparent in a state where the reflecting surface 16a and the lens sheet 17 are bonded, and is a pressure-sensitive adhesive that is substantially transparent in a state where the pressure-sensitive adhesive layer 18 stably bonds the two. Is used.

Thus, when an air layer is provided between the lens sheet 17 and the reflecting surface 16a, the surface of the reflecting surface 16a made of the diffusing reflecting sheet 16 has minute irregularities for performing diffuse reflection, and air By providing the layer, the diffuse reflection of the reflecting surface 16a can be made more effective. Thereby, the brightness | luminance of the reflected light by the reflective surface 16a can be maintained in a high state. For example, when the adhesive layer 18 is provided on substantially the entire surface between the reflective surface 16a and the lens sheet 17, reflected light with sufficient luminance can be obtained from the reflective surface 16a, but minute irregularities on the surface of the reflective surface 16a are adhesive. The reflectance on the reflecting surface 16a may be slightly lowered by being filled with the agent, and reflected light with higher luminance can be obtained by providing an air layer on the surface of the reflecting surface 16a.
In the present embodiment, the pressure-sensitive adhesive layer 18 is interposed in order to form an air layer between the lens sheet 17 and the reflective surface 16a. For example, the lens sheet 17 is stacked on the reflective surface 16a. A minute air layer exists only by matching, and the lens sheet may be fixed in such a state.

  Further, the reflection surface 16 a on which the lens sheet 17 is fixed on the surface is formed as a diffusion reflection surface by using the diffusion reflection sheet 16. In this case, the reflecting surface 16a reflects the light from the light source 13 while diffusing it, and the reflected light can be emitted through the prism lens sheet 17, so that uniform reflected light can be emitted to the diffusion plate 12. Thereby, the light emission quality in the light emission surface 12a can be improved.

  The lens sheet 17 has the lens surface 17b on the inner side of the lower frame 11, and the reflecting surface of the diffuse reflecting sheet 16 so that the longitudinal direction of the lens strip 17a is substantially parallel to the straight tubular portion 13a1 of the cold cathode tube 13a. It is fixed on the surface of 16a. In this case, since the lens strip 17a of the lens sheet 17 is disposed along the longitudinal direction of the cold cathode tube 13a, the light emitted from the cold cathode tube 13a can be effectively condensed by the lens sheet 17. Accordingly, the brightness of the reflected light from the reflecting surface 16a can be further increased.

  The lens surface of the lens sheet 17 is covered with a light resistant layer 17c. In this case, since the ultraviolet rays from the light source 13 can be blocked by the light-resistant layer 17c, it is possible to prevent the prism lens sheet 17 formed of an acrylic resin or the like from being deteriorated such as yellowing. Further, a light proofing agent may be added to the prism lens sheet 17. As a result, it is possible to prevent the luminance, light emission quality, and the like of the direct type backlight 1 from decreasing with time. However, in the case of a direct type backlight used for toys and the like whose product life is about 500 hours, it is not necessary to prevent deterioration by a light-resistant layer or a light-resistant agent.

  In the present embodiment, the lens sheet 17 is not disposed on the reflection surface 14a of the inner wall bottom surface 11a of the lower frame 11 and the reflection surface 15a of the end-side inner wall side surface 11b. When the lens sheet 17 is disposed on the reflecting surface 16a and the lens sheet is also disposed on the reflecting surface 14a and the reflecting surface 15a, an effect that is not particularly problematic as a product can be obtained, but the lens sheet 17 is disposed only on the reflecting surface 16a. This is because a better effect was obtained when they were arranged.

Next, a description will be given of test results obtained by the inventors of the present invention by experimentally measuring the luminance distribution on the light emitting surface 12a of the direct type backlight according to the embodiment.
In this test, the direct type backlight 1 of the present embodiment is used as an example product, and the direct type backlight using only the diffuse reflection sheet 16 as the reflective surface 16a is used as a comparative example product (the reflective surface 16a in the present embodiment). The state in which the prism lens sheet 17 is removed from is used. In this experiment, the test was performed with the upper frame 20 removed.

  4A is a cross-sectional view showing the angle of the reflecting surface 16a of the parallel inner wall side surface 11c in the lower frame 11 and the positional relationship of the cold cathode tubes 13a. In this test, the pitch dimension L of the straight tubular portion 13a1 of the cold cathode tube 13a in FIG. 4A is 23.5 mm, and the cold cathode tube 13a arranged at the outermost end 14a1 of the reflecting surface 14a. The distance dimension l which is the distance from the center is L / 0 (0 mm), L / 4 (5.875 mm), L / 2 (11.75 mm) with respect to the pitch dimension L (23.5 mm) of the cold cathode tube 13a. ), L (23.5 mm), and the inclination angle θ of the reflecting surface 16a with respect to the broken line T indicating the surface extending outward from the reflecting surface 14a is 45, 60, or 75 degrees. The brightness distribution of the light emitting surface 12a was measured for each of the example product and the comparative example product by changing the value of the type.

  5 to 7 are graphs showing the measurement results of the luminance distribution on the light emitting surface 12a of the example product and the comparative product, respectively. These graphs show the measurement results of the luminance distribution on the broken line X between the point X1 and the point X2, which are approximately the center in the left-right direction of the light emitting surface 12a shown in FIG. 4B. That is, the obtained luminance distribution measurement result indicates the luminance distribution in the vertical direction of the light emitting surface 12a. The horizontal axis in the graph indicates the position on the broken line X between the point X1 and the point X2, and the vertical axis indicates the luminance. Moreover, the measurement result of the Example product in the graph is indicated by a solid line J, the measurement result of the Comparative Example product performed under the same conditions is indicated by a broken line H, and both are shown superimposed on the same graph.

  Further, in all the experiments shown below, the experiment was performed using only the parallel inner wall side surface 11c on the point X1 side (left side in the graph) of the direct type backlight 1, and the parallel inner wall side surface 11c on the point X2 side The lens sheet 17 was not disposed only by attaching the reflection sheet 16. Therefore, the measurement results shown below will be described by paying attention to only the half portion on the point X1 side.

FIGS. 5A to 5D show the results when the inclination angle θ of the reflecting surface 16a is 45 degrees. FIG. 5A shows the distance dimension l of L / 0, and FIG. 5B shows the distance dimension l of L. / 4 and (c) are the results when the distance dimension l is L / 2, and (d) is the result when the distance dimension l is L.
In FIG. 5, when the brightness of the portion surrounded by the broken line near the end on the point X1 side is compared between the example product and the comparative example product, the brightness of the example product increases regardless of the distance dimension l. You can see that

6 (a) to 6 (d) show the results when the inclination angle θ of the reflecting surface 16a is 60 degrees. FIG. 6 (a) shows the distance dimension l of L / 0, and FIG. 6 (b) shows the distance dimension l of L. / 4 and (c) are the results when the distance dimension l is L / 2, and (d) is the result when the distance dimension l is L.
In FIG. 6, when the brightness of the portion surrounded by the broken line near the end on the point X1 side is compared between the example product and the comparative product, the distance dimension l is any in the same manner as in FIG. It can also be seen that the brightness of the example product is increased.

FIGS. 7A to 7D all show the results when the inclination angle θ of the reflecting surface 16a is 75 degrees. FIG. 7A shows the distance dimension l of L / 0, and FIG. 7B shows the distance dimension l of L. / 4 and (c) are the results when the distance dimension l is L / 2, and (d) is the result when the distance dimension l is L.
In FIG. 7, when the brightness of the portion surrounded by the broken line near the end on the point X1 side is compared between the example product and the comparative product, the distance dimension l is any as in the case of FIGS. It can be seen that the brightness of the example product is also increased.

  Thus, it was confirmed that the direct type backlight 1 of the present embodiment, which is an example product, has an effect of increasing the luminance in the vicinity of the end portion of the light emitting surface 12a under any conditions.

  As can be seen from the experimental results, the direct type backlight 1 according to this embodiment has a lens sheet on the reflection surface 16a of the diffuse reflection sheet 16 attached to the parallel-side inner wall side surface 11c of the lower frame 11. By disposing 17, the light emitted from the light source 13 toward the reflecting surface 16a can be reflected appropriately. Accordingly, it is possible to increase the luminance near the end of the light emitting surface 12a and to suppress the occurrence of a luminance reduction portion that appears near the end of the light emitting surface 12a.

  That is, the direct type backlight 1 of the present embodiment has an effect of increasing the luminance in the range U shown in FIG. For example, in a direct type backlight that does not include the lens sheet 17 on the reflection surface 16a as in the conventional example, the reflection surfaces 15a and 16a located behind this range U are arranged at a certain angle with respect to the diffusion plate 12. Therefore, the brightness tends to be relatively low. However, according to the direct type backlight 1 of the present embodiment, the luminance near the end of the light emitting surface 12a including the range U can be increased, and the edge 20a of the upper frame 20 can be narrowed to the end of the reflecting surface 16a. As a result, the degree of freedom in designing the direct backlight 1 can be increased, such as downsizing.

  Moreover, in the direct type backlight 1 of this embodiment, since low-cost materials, such as the diffuse reflection sheet 16 and the prism lens sheet 17, should just be fixed by a simple method, without positioning precisely as mentioned above, cost Thus, it is possible to provide a direct type backlight in which a decrease in luminance in the vicinity of the end portion is suppressed.

  Further, in the direct type backlight 1 according to the present embodiment in which the lens sheet 17 is disposed on the reflection surface 16a, it is easier to increase the luminance when the inclination angle θ is increased. In particular, the inclination angle θ of the reflection surface 16a is set to 45 degrees. By setting as described above, the reflected light from the reflecting surface 16a can be more reliably emitted to the vicinity of the end of the diffusion plate 12 while increasing the luminance. Therefore, the brightness near the end of the light emitting surface 12a can be effectively increased.

Next, the luminance distributions of the example products shown in FIGS. 5A, 6A, and 7A in which the distance dimension l is set to L / 0 (0 mm) are shown in any case. However, the luminance near the end on the point X1 side is relatively large compared to the luminance near the center of the light emitting surface 12a. This may reduce the light emission quality of the entire screen. 5 (d), FIG. 6 (d), and FIG. 7 (d) in which the distance dimension l is set to L (23.5 mm), the absolute value in the vicinity of the end in any case. The brightness was low and no improvement in light emission quality was observed.
On the other hand, the distance dimension 1 is set to L / 4 (5.875 mm) and L / 2 (11.75 mm). Looking at the luminance distributions of the example products 7 (b) and 7 (c), in this case, there is no significant difference in luminance compared to the luminance near the center of the light emitting surface 12a, and the effect of improving the light emitting quality. Is high.

  From the above results, in the direct type backlight 1 according to the present embodiment, the distance dimension l is preferably L / 4 (5.875 mm) to L / 2 (11.75 mm). By doing so, the light reflected by the reflective surface 16a on which the lens sheet 17 is disposed can have a luminance suitable for suppressing a luminance reduction portion that occurs near the end of the light emitting surface 12a, thereby improving the light emission quality. Effect is obtained.

  5B, the luminance in the vicinity of the end on the side of the point X1 gradually decreases from the vicinity of the center of the light emitting surface 12a toward the point X1. On the other hand, in the cases of FIG. 6B and FIG. 7B, the luminance near the end on the point X1 side changes from the vicinity of the center of the light emitting surface 12a while maintaining a constant luminance, and the diagram toward the point X1. Compared with the case of 5 (b), it is rapidly decreasing. That is, this indicates that high luminance is maintained up to the vicinity of the end portion of the light emitting surface 12a. In addition, when such a tendency is compared with the case where only the inclination angle θ is changed and the other conditions are the same, the same tendency is observed in any case.

From the above, in the direct type backlight 1 according to the present embodiment, it is preferable that the inclination angle of the reflecting surface 16a is 60 degrees or more. In this case, since the reflected light from the reflecting surface 16a whose luminance is increased by the lens sheet 17 is preferably emitted near the end of the diffuser plate 12, high luminance can be maintained near the end of the light emitting surface 12a. .
Further, when the inclination angle θ is 60 degrees or more and the distance dimension 1 is L / 4 (5.875 mm) to L / 2 (11.75 mm), the reflected light from the reflecting surface 16 a provided with the lens sheet 17 is more Since the light is preferably emitted to the vicinity of the end portion of the diffusion plate 12, a good light emission quality can be obtained.

  The lighting device of the present invention is not limited to the above embodiment, and the shape, material and arrangement of the lens layer, the material of the reflective layer, the configuration of the lighting device, etc. are appropriately changed based on the spirit of the present invention. can do.

It is sectional drawing which shows typically the structure of the direct type | mold backlight which concerns on 1st embodiment of this invention. It is a top view of the state which removed the diffusion plate 12 of the direct type | mold backlight 1 in FIG. Further, (b) is a sectional view taken along the line SS in (a). It is the enlarged view which showed typically the cross section of the part enclosed with the broken line A in FIG. Sectional drawing which shows the positional relationship in the inclination angle of the reflective surface 16a and the inner wall bottom face 11a of the cold cathode tube 13a, (b) is a top view of the direct type | mold backlight for demonstrating the location which measured luminance distribution. 4A to 4D, the lens sheet is disposed only on the reflection surface 16a on the point X1 side in FIG. 4 (no lens sheet is disposed on the reflection surface 16a on the point X2 side), and the inclination angle θ is set to 45 degrees. (A) is a distance dimension l of L / 0, (b) is a distance dimension l of L / 4, (c) is a distance dimension l of L / 2, and (d). Is a graph in which the distance dimension l is L. 4A to 4D, the lens sheet is disposed only on the reflection surface 16a on the point X1 side in FIG. 4 (no lens sheet is disposed on the reflection surface 16a on the point X2 side), and the inclination angle θ is set to 60 degrees. (A) is a distance dimension l of L / 0, (b) is a distance dimension l of L / 4, (c) is a distance dimension l of L / 2, and (d). Is a graph in which the distance dimension l is L. 4A to 4D, a lens sheet is disposed only on the reflection surface 16a on the point X1 side in FIG. 4 (no lens sheet is disposed on the reflection surface 16a on the point X2 side), and the inclination angle θ is set to 75 degrees. (A) is a distance dimension l of L / 0, (b) is a distance dimension l of L / 4, (c) is a distance dimension l of L / 2, and (d). Is a graph in which the distance dimension l is L.

Explanation of symbols

1 Direct type backlight (lighting device)
12 diffuser plate 12a light emitting surface 13 light source 13a1 straight tubular portion 14a reflecting surface (bottom reflecting surface)
16a Reflective surface (side reflective surface)
17 Lens sheet (lens layer)
17a Lens strip 17b Lens surface 17c Light-resistant layer θ Inclination angle

Claims (6)

A diffuser plate serving as a light emitting surface; a light source disposed behind the diffuser plate; a bottom surface reflecting surface disposed opposite to the diffuser plate behind the light source and reflecting light from the light source toward the diffuser plate; In a lighting device having a side surface reflecting surface disposed on a side portion of the bottom surface reflecting surface and reflecting light from the light source toward the diffuser plate,
An illumination device, wherein a lens layer having a lens surface facing the diffusion plate is disposed on the side reflection surface. The light source has a straight tubular section;
The lighting device according to claim 1, wherein a plurality of fine lens strips are provided on a lens surface of the lens layer, and a longitudinal direction of the lens strips is substantially parallel to the straight tubular portion.   The lighting device according to claim 1, wherein an inclination angle of the side surface reflection surface with respect to a surface obtained by extending the bottom surface reflection surface outward is 45 degrees or more.   The lighting device according to claim 1, wherein the side reflection surface is a diffuse reflection surface.   The lighting device according to claim 4, wherein an air layer is provided between the side reflecting surface and the lens layer.   The lighting device according to claim 1, wherein the lens layer has light resistance.

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