JP2005276518A - Lighting system and reflecting member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lighting system and a reflecting member which can increase light emitting quality. <P>SOLUTION: The lighting system 1 has a diffuser 12 which is a light emitting surface 12a, a light source 13 disposed behind the diffuser and a diffusion reflecting surface 15a disposed behind the light source facing the diffuser and reflecting the light of the light source to the diffuser. A lens layer 16 with a lens surface on the diffuser side is disposed on the diffusion reflecting surface. Thereby, the distribution of the light entering the diffuser can be made uniform to obtain the high light emitting quality while maintaining high luminance. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an illumination device and a reflection member 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. In this direct type backlight, a light source is arranged behind (directly below) a diffusion plate as a planar diffusing member that becomes a light emitting surface, and a reflection surface that reflects the light of the light source toward the diffusion plate is arranged behind it. It is configured to do.
In such an illuminating device, if the light on the light emitting surface is non-uniform light, for example, light with a lamp image remaining, a luminance difference occurs 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 of the light emission quality with uniform luminance distribution over the whole light emission surface is requested | required.
Conventionally, as the reflective surface behind the light source of the above-mentioned lighting device, (1) a metallic glossy sheet having a glossy surface obtained by vapor deposition of metal, (2) a reflective plate formed into a corrugated shape or a chevron, and (3) diffusion A reflective sheet or the like has 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 illuminating device using the metallic glossy sheet of (1) above, the brightness of the reflected light is high, but it is difficult to eliminate the lamp image because the metallic glossy surface regularly reflects the light from the light source. In addition, when the reflector of (2) is used, it is difficult to set an optimum shape for improving the light emission quality because the shape of the reflector is complicated, and further, it is necessary to process the reflector and the light source and reflector There is a problem that it is necessary to set the positional relationship with the shape of the object with high accuracy. In addition, when the diffuse reflection sheet of (3) is used, since the light from the light source is diffusely reflected, a light emission quality better than (1) and (2) can be obtained. A higher light emission quality has been demanded.
This invention is made | formed in view of such a situation, and it aims at provision of the illuminating device and reflecting member which can obtain higher luminous quality.

  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. An illumination device having a diffuse reflection surface is characterized in that a lens layer having a lens surface on the diffusion plate side is disposed on the diffuse reflection surface.

  According to the illuminating device configured as described above, a lens layer is disposed on the diffuse reflection surface with the lens surface facing the diffuser plate, thereby making the distribution of light emitted to the diffuser plate uniform. The present inventors have found that a high luminous quality can be obtained. That is, the inventor experimentally found that the distribution of the light emitted to the diffuser plate becomes uniform by disposing a lens layer on the diffuse reflection surface, and based on this knowledge, completed the present invention. It was.

  In the illumination device, the lens layer may be provided with substantially the entire surface integrally with the diffuse reflection surface. In this case, even if heat from the light source is applied to the lens layer, the lens layer is provided integrally with the diffuse reflection surface, so that deformation such as warpage or distortion of the lens layer can be prevented, and the diffusion is performed. It is possible to prevent partial separation from the reflecting surface. As a result, the space between the diffuse reflection surface and the lens layer can be prevented from becoming non-uniform, and light refraction between them can be stabilized. Therefore, stable reflected light can be obtained and high light emission quality can be obtained.

  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.

In addition, the reflecting member of the present invention is a reflecting member that is disposed so as to face the diffusing plate serving as a light emitting surface and reflects light from a light source disposed between the diffusing plate and the diffusing plate. The light source includes a diffuse reflection layer for reflecting the light of the light source and a lens layer formed on the reflection layer.
According to the reflection member configured as described above, the light from the light source is reflected while being diffused by the diffuse reflection layer, and the reflected light further passes through the lens layer to thereby output outgoing light. It can be reflected uniformly. Therefore, it can be suitably used as a reflecting surface of the lighting device.

  As described above, according to the illuminating device and the reflecting member according to the present invention, by providing the lens layer on the diffuse reflection surface, it is possible to obtain a high light emission quality with a uniform luminance distribution over the entire light emission surface.

  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. 1 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 frame 11 having an opening on one side, a diffusion plate 12 as a planar diffusion member disposed so as to close the opening, and a back (directly below) the diffusion plate 12. And a light source 13 to be arranged.

  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. At this time, the light transmittance of the diffusion plate 12 is 30%. Such a diffusion plate 12 is disposed so as to close the opening of the 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.

  FIG. 2 is a plan view showing a state in which the diffusion plate 12 of the direct type backlight according to the present embodiment is removed. As shown in FIG. 2, the light source 13 includes, for example, four cold cathode tubes 13a each having a U-shaped tubular body having a diameter of 3 mm. Each of the light sources 13 is attached to a connector 13b and supported by a lamp support base (not shown). In the frame 11. The long side portions 13a1 of the cold cathode tubes 13a are arranged in parallel so as to be substantially parallel to the horizontal direction of the frame at intervals of 20 mm. The light source 13 is connected to an inverter or the like (not shown) so that it can be turned on / off.

  The frame 11 is formed of, for example, an aluminum alloy, and has a rectangular bottom surface and side surfaces (lower side surface, upper side surface, left and right side surfaces) erected so as to spread from the bottom surface to the opening side, and one surface is open. It is formed in the shape. Referring also to FIG. 1, a diffuse reflection sheet 14 is attached to the inner wall side surface 11 a (lower side surface, upper side surface, left and right side surfaces) of the frame 11 with an adhesive or the like, and the surface of the diffuse reflection sheet 14 is respectively The reflection surface reflects light from the light source 13. 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 reflection member 18 comprising a diffuse reflection sheet 15 and a lens sheet 16 superimposed as a lens layer on the reflection surface 15a of the diffuse reflection sheet 15 is attached to the inner wall bottom surface 11b of the frame 11 with an adhesive or the like. It has been. The above-mentioned “E60V” is used for the diffusion sheet 15, and the lens sheet 16 is fixed to the diffusion reflection sheet 15 by adhering a part thereof with an adhesive or the like on the reflection surface 15 a. Yes. Thus, in the state where the lens sheet 16 is superimposed on the surface of the reflecting surface 15a, an air layer is interposed due to the presence of a minute gap between the two.
In this case, the surface of the reflection surface 15a made of the diffuse reflection sheet 15 has fine irregularities for performing diffuse reflection. By providing the air layer, the reflection of the reflection surface 15a is more effective. Can be a thing.
In addition, the lens sheet 16 may be fixed in a state of being spaced from the reflecting surface 15a.

  The lens sheet 16 is a plate-like body formed of a transparent resin such as acrylic or polycarbonate. Specifically, in the present 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 16 constitutes a prism lens sheet having a lens surface 16b provided with a plurality of fine cross-sectional triangular lens strips 16a at equal pitches in one direction. In the present embodiment, the lens sheet 16 formed on a lens strip having a triangular cross section is used as the lens layer. For example, a lens sheet having a lens strip having a semicircular cross section may be used.

  The lens sheet 16 is superposed on the upper surface of the diffuse reflection sheet 15 so that the lens surface 16b is on the diffusion plate 12 side and the longitudinal direction of the lens strip 16a is parallel to the long side portion 13a1 of the cold cathode tube 13a. Has been. On the other hand, the longitudinal direction of the lens strip 16a of the lens sheet 16 may be arranged in a direction orthogonal to the long side portion 13a1. The reason is that there is no difference in the effect on the reflected light due to the difference in the longitudinal direction of the lens strip 16a.

  The lens surface of the lens sheet 16 is covered with a light-resistant layer 16c. In this case, since the ultraviolet rays from the light source 13 can be blocked by the light-resistant layer 16c, it is possible to prevent the lens sheet 16 formed of an acrylic resin or the like from being deteriorated such as yellowing. Further, a light proofing agent may be added to the lens sheet 16. 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.

  Since such a reflection member 18 includes the lens sheet 16 on the reflection surface 15 a, it can be suitably used as a reflection surface of the direct type backlight 1 if it is attached to the inner wall surface of the frame 11. Moreover, since the reflective surface 15a which has a lens layer can be comprised only by sticking the reflective member 18 to the inner-wall bottom face 11b, the attachment property improves. In addition, the reflecting member 18 can be applied not only as a reflecting surface of a direct type backlight as in the present embodiment, but also, for example, a reflecting surface of an indoor lighting device or a reflecting plate of other similar lighting devices. .

  Further, in the reflection member 18, the reflection surface 15 a on which the lens sheet 16 is superimposed is a diffuse reflection surface by using the white diffuse reflection sheet 15. In this case, the reflecting surface 15a reflects the light from the light source 13 while diffusing it, and the reflected light can be emitted through the lens sheet 16, 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.

  In the present embodiment, the reflecting member 18 including the lens sheet 16 is not used for the reflecting surface of the inner wall side surface 11 a of the frame 11. Even when the reflecting member 18 is used for the inner wall side surface 11a, a good light emitting quality with no particular problem can be obtained as a product. However, when the reflecting member 18 is not used for the inner wall side surface 11a, a better light emitting quality is obtained. This is because of

Next, a description will be given of test results conducted by the present inventor for the direct type backlight according to the embodiment.
The direct-type backlight 1 of the above embodiment is used as an example product, and the direct-type backlight that does not include the lens sheet 16 on the reflection surface 15a of the diffuse reflection sheet 15 is used as a comparative example product. Was experimentally measured and evaluated. The results are shown in Table 1 below.

In Table 1, all of the comparative product and the example product were measured under the same conditions except for the presence or absence of the lens sheet 16. According to this, it can be seen that the luminance and chromaticity are substantially the same for the comparative example product and the example product.
As for the light emission quality, an example of the result of measuring the luminance distribution on the light emitting surface 12a is shown. 4A is a graph showing the result of measuring the relative luminance distribution on the light emitting surface of the comparative product, and FIG. 4B is the result of measuring the relative luminance distribution on the light emitting surface of the example product. FIG. As shown in FIG. 4C, this luminance distribution represents the measurement result of the luminance distribution along the X1-X2 line, which is substantially the center in the left-right direction of the light emitting surface 12a. That is, the obtained luminance distribution measurement result indicates the luminance distribution in the vertical direction of the light emitting surface. In the graph, the horizontal axis indicates the position on the X1-X2 line, and the vertical axis indicates the luminance.

  According to FIG. 4A, in the luminance distribution of the comparative example product, an increase or decrease that undulates with a relatively large wavelength as seen in a portion surrounded by a broken line Y in the figure is seen over substantially the entire area. This is because the lamp image of the light source 13 appears, and the light emission quality is not good. On the other hand, the example product exhibits a gentle and uniform distribution state as compared with the comparative example product, and it can be said that the light emission quality is good. As described above, it was confirmed that the direct-type backlight 1 according to the present embodiment, which is an example product, can obtain a high emission quality state in which the lamp image of the light source 13 does not appear remarkably.

As described above, as is apparent from the experimental results, the direct type backlight 1 according to the present embodiment has the reflecting member 18 in which the lens sheet 16 is disposed on the reflecting surface 15 a of the diffuse reflecting sheet 15 on the bottom surface 11 b of the frame 11. By using it, the light emitted from the light source 13 toward the reflecting surface 15a can be suitably reflected, and the distribution of the light emitted to the diffusion plate 12 can be made uniform, so that the luminance and chromaticity are not impaired. High emission quality can be obtained.
Moreover, in the direct type backlight 1 of this embodiment, since low-cost materials, such as the diffuse reflection sheet 15 and the lens sheet 16, may be fixed by a simple method without particularly precisely positioning as described above, the cost can be reduced. It is possible to provide a direct type backlight with high luminous quality while suppressing it.

  Further, in order to verify the thinning of the direct type backlight according to the present invention, the inventor changes the thickness t of the direct type backlight 1 by changing the interval t between the light source 13 and the diffusion plate 12 in FIG. Two types (15 mm and 18 mm) with different T were prepared and the same experiment was performed. The results are shown in Table 2 below.

  In Table 2, the comparative product and the example product were all measured under the same conditions except for the presence or absence of the lens sheet 16 on the inner wall bottom surface of the frame 11 and the thickness dimension T of the direct type backlight 1. As a result, although the thickness dimension T was reduced in the example product, both the light emission quality and the luminance were the same as the comparative product. Usually, if the distance t between the light source 13 and the diffusion plate 12 is reduced, the light emission quality tends to deteriorate. In such a case, the reflection member 18 having the lens sheet 16 disposed on the reflection surface 15a is used. Thus, it can be seen that the light emission quality and the luminance can be maintained equal to those of the comparative product. That is, the direct type backlight 1 of the present embodiment can make the direct type backlight 1 thinner by improving the light emission quality by the reflecting member 18 including the lens sheet 16.

  In addition, the present inventor has verified the brightness improvement of the direct type backlight 1 according to the present invention. The results are shown in Table 3 below.

  In Table 3, all of the comparative product and the example product were measured under the same conditions except that the diffuser plate 12 having the lens sheet 16 on the inner wall bottom surface of the frame and having different light transmittance was used. As a result, in the example product, the light emission quality was the same as that of the comparative example product, and the luminance was improved as compared with the comparative product. Therefore, in the example product using the lens sheet 16, the light emission quality is improved. Therefore, even if the diffusion plate 12 having a high light transmittance including a factor for reducing the light emission quality is used, the product of the comparative example is used. It can be seen that the same luminous quality can be maintained. That is, the direct type backlight 1 of the present embodiment makes it possible to use a diffusion plate having a high light transmittance by improving the light emission quality, and as a result, the luminance can be improved.

  FIG. 5 is a cross-sectional view schematically showing the structure of the bottom surface of the inner wall of the direct type backlight according to the second embodiment of the present invention. The main difference between the present embodiment and the first embodiment is that the lens sheet 16 and the diffuse reflection sheet 15 are bonded to each other by an adhesive or the like so that the reflection surface 15a of the diffuse reflection sheet 15 is on the surface. The reflecting member 18 is provided with a lens layer integrally therewith. Since other points are the same as those of the first embodiment, description thereof is omitted.

  In this case, in the reflecting member 18, the lens sheet 16 as a lens layer is bonded to substantially the entire surface of the reflecting surface 15 a through the pressure-sensitive adhesive layer 17 and is integrated. The pressure-sensitive adhesive layer 17 is preferably substantially transparent in a state in which the diffuse reflection sheet 15 and the lens sheet 16 are bonded, and a pressure-sensitive adhesive that is substantially transparent in a state in which the pressure-sensitive adhesive layer 17 stably bonds the two is used. It is used.

Since the lens sheet 16 is disposed in the immediate vicinity of the cold cathode tube 13a, the lens sheet 16 is exposed to a relatively high temperature environment due to heat generated by the cold cathode tube 13a. Since the lens sheet 16 is formed of a transparent resin or the like, deformation such as warpage or strain is likely to occur under such a relatively high temperature environment.
However, in the reflecting member 18 of the present embodiment, the lens sheet 16 is integrally bonded to the entire surface of the reflecting surface 15 a, so that even if heat generated by the cold cathode tube 13 a is applied to the lens sheet 16, Deformation can be prevented, and partial separation from the reflecting surface 15a can be prevented. As a result, the space between the reflecting surface 15a and the lens sheet 16 can be prevented from becoming non-uniform, and light refraction and the like between them can be stabilized. Therefore, stable reflected light can be obtained and high light emission quality can be obtained.

FIG. 6 is a cross-sectional view schematically showing the structure of the bottom surface of the inner wall of the direct type backlight according to the third embodiment of the present invention. The main difference between the present embodiment and the second embodiment is that a reflecting member in which a lens layer 16 is integrally formed directly on substantially the entire surface of the reflecting surface 15a of the diffuse reflecting sheet 15 using a UV curable resin. The point is 18. Since other points are the same as those of the second embodiment, description thereof is omitted.
The lens layer 16 using this UV curable resin was formed as follows. That is, the UV curable resin is applied with an appropriate thickness on the surface of the reflection surface 15a of the diffuse reflection sheet 15. Then, a plurality of fine lens sections having a triangular cross section are formed on the surface with a relief mold or the like, for example, at an equal pitch. Thereafter, the UV curable resin is cured by irradiating ultraviolet rays, and the lens layer 16 is formed.

  When such a reflection member 18 is used, in addition to being able to prevent the lens layer 16 from being deformed such as warping or distortion and being partially separated from the reflection surface 15a, the diffuse reflection sheet 15 and the lens layer 16 are prevented. Therefore, the reflected light from the diffuse reflection sheet 15 is not attenuated unnecessarily. For this reason, more suitable reflected light can be obtained.

  The lighting device and the reflecting member of the present invention are not limited to the above embodiment, and the shape, material, and arrangement of the lens layer, the material of the reflecting layer, the configuration of the reflecting member, the material, the configuration of the lighting device, etc. These can be changed as appropriate based on the gist of the present invention.

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. It is the enlarged view which showed typically the cross section of the part enclosed with the broken line A in FIG. (A) is a graph showing the result of measuring the luminance distribution on the light emitting surface of the comparative product, (b) is a graph showing the result of measuring the luminance distribution on the light emitting surface of the example product, (c). FIG. 3 is a plan view of a direct type backlight for explaining a location where luminance distribution is measured. It is sectional drawing which shows typically the structure of the inner-wall bottom face of the direct type | mold backlight which concerns on 2nd embodiment of this invention. It is sectional drawing which shows typically the structure of the inner-wall bottom face of the direct type backlight which concerns on 3rd embodiment of this invention.

Explanation of symbols

1 Direct type backlight (lighting device)
12 Diffusion plate 12a Light emitting surface 13 Light source 15 Diffuse reflection sheet (diffuse reflection layer)
15a Reflective surface (diffuse reflective surface)
16 Lens sheet (lens layer)
16b Lens surface 16c Light-resistant layer 18 Reflective member

Claims (4)

A diffusing plate to be a light emitting surface; a light source disposed behind the diffusing plate; a diffusive reflecting surface disposed opposite to the diffusing plate behind the light source and reflecting light from the light source toward the diffusing plate; In a lighting device having
An illumination device, wherein a lens layer having a lens surface on the diffusion plate side is disposed on the diffuse reflection surface.   The illumination device according to claim 1, wherein the lens layer is provided integrally with the diffuse reflection surface over substantially the entire surface thereof.   The lighting device according to claim 1, wherein the lens layer has light resistance. A reflective member for reflecting light from a light source disposed between the diffuser plate and the diffuser plate, which is a light emitting surface, to the diffuser plate,
A reflection member comprising: a diffuse reflection layer for reflecting light from the light source; and a lens layer formed on the reflection layer.

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