TWI260446B - Planar light source device, and display device with planar light source - Google Patents

Abstract

This invention provides a planar light source device. It can automatically correct the variation in chromaticity and luminance of the illuminating ray for the changes in temperature or aging. A planar light source device comprises a case, a diffuse plate, a light source, a reflecting plate, and a controller. The case possesses an aperture. The diffuse plate is arranged at the aperture and diffuses the entered light. The light source is equipped in the case. The reflecting plate reflects the light from the light source toward the diffuse plate. The device has the characteristic that comprises a light sensor. The light sensor is arranged opposed to the diffusion plate. It detects the light from the diffusion plate. According to the detected value of the light sensor, the controller adjusts the amount of emitting light from the light source.

Description

1260446 V. Invention - ---- [Inventive households] The technical field of this 2nd genus] The device, the hairline system has a flat light source device and the display with the device has a detailed description of the transmission A liquid crystal display device, a display device such as a kanban or a guide lamp for supplying the stencil pattern or a character panel, and a flat light source device for illuminating light of the display device. The prior art flat-panel light source device is described in Japanese Laid-Open Patent Publication No. Hei. No. Hei. No. Hei. No. Hei. 4 π 1 w shown in FIG. 1 , the sensor 2 配置 is disposed on the end surface Ijc of the LED module 16 on which the light guide plate 13 is disposed, and after detecting the energy of each wavelength band of the external light, the R is adjusted according to the measurement result. Lights of (red), G (green), and beta (blue) emit energy. In the case of the flat light source device described in Japanese Laid-Open Patent Publication No. Hei No. Hei. No. Hei. No. Hei. That is, since the temperature dependence of the LED wheel is strong, the color product and the brightness become a problem due to temperature changes in the surroundings. Further, since such temperature dependence differs depending on the respective luminescent colors of R, G, and B, there is a problem that the white balance of the illumination light changes due to the temperature change around. There is also a problem that such a change in the light-emitting characteristics occurs between LEDs of the same luminescent color. Further, there is a problem in that the life characteristics of the LED vary depending on each of r, g, and B. In view of the above problems, an object of the present invention is to provide a flat light source device and a display device having the same, which can automatically correct changes in chromaticity and brightness of illumination light which occur due to temperature changes or aging.

2066-6449-PF(N3); Ahddub.ptd Page 5 1260446 V. Inventive Description (2) [Invention] The flat light source device of the present invention includes a housing having an opening, and a diffusing plate disposed on The opening portion diffuses the incident light; the light source is disposed in the housing; and the reflecting plate reflects the light from the light source toward the diffusing plate; and the light sensor includes a light sensor and the diffusing plate The arrangement detects light from the diffuser; and the control device adjusts the amount of light emitted from the light source according to the measured value of the light sensor. Further, the flat light source device of the present invention includes: a casing having an opening; a diffuser plate disposed in the opening to diffuse incident light; a pair of light sources disposed on both sides of the casing; and reflection a plate that reflects light from the light source toward the diffusing plate; and the method includes: two light sensors disposed opposite to the diffusing plate to detect light from the diffusing plate; and a control device according to the light The respective detected values of the sensors adjust the amount of light emitted from the respective sources. Further, the flat light source device of the present invention includes a housing having an opening, a pair of diffusing plates disposed in the opening, a light source disposed on a bottom surface of the housing, and a reflecting plate disposed on the bottom plate The bottom surface reflects light emitted from the light source; the light sensor is disposed on the bottom surface of the housing, detects light from the diffusing plate, and controls the device, and adjusts according to the detected value of the light sensor The amount of light emitted by the light source. Further, a display device of the present invention is characterized by comprising: the flat light source device; and a display element for modulating light from the flat light source device.

2066-6449-PF(N3); Ahddub.p td Page 6 1260446 V. Description of the Invention (3) Hereinafter, the implementation of the flat light source device and the display device having the same according to the present invention will be described with reference to the drawings. example. In addition, the same symbols are denoted by the same reference numerals in the respective drawings. Embodiment 1 Hereinafter, a flat light source device of the present invention will be described in detail using the drawings. Fig. 1 is a plan view showing a schematic configuration of a flat light source device according to a first embodiment of the present invention, and Fig. 2 is a cross-sectional view taken along line A-A of Fig. 1 and a cross-sectional view of a main portion taken along line B-B of Fig. 1. In Figs. 1 to 3, 1 is a casing having an opening 1a. A diffuser 2 for uniformly diffusing incident light is disposed in the opening 1a of the body 1. 4 is a plurality of point light sources composed of a light-emitting diode (hereinafter referred to as an LED), a point light source 4a that emits red (r) light, a point light source 4b that emits green (G) light, and an emission blue ( B) The light point light source 4c is constructed. Further, a laser diode (Laser Diode: LD) or the like can be used for the point light source 4 in addition to the LED. A plurality of point light sources 4 are arranged on the substrate 3 along the inner side surface lc of the upper and lower sides of the casing 1. The point light sources 4a, 4b and 4c provided on the substrate 3 are set in accordance with the chromaticity of the illumination light and the required brightness. The flat light source device shown in Fig. 1 is arranged in the order of repetition of G, B, G, R, G, B, and the like. 5 is a deflection angle element disposed at a position where the point light source 4 emits light. The deflecting angle element 5 has a trapezoidal cross-sectional shape, and refracts light emitted from the point light source 4 toward the reflecting plate 6 disposed on the bottom surface 1b of the casing 1. The reflector 6 is composed of a member in which the specular reflection portion 6 2 directly reflects the light incident from the deflecting angle element 5 toward the diffusing plate 2, and the scattered diffusing portion 61. The 7-reflector ' surrounds the point source 4, The light emitted from the point light source 4 is directed to the housing 1

2066-6449-PF(N3); Ahddub.ptd Page 7 1260446 V. Description of the Invention (4) The light of the inner wall is reflected toward the deflecting element 5. The 8-series photosensor is disposed in a storage portion 丨d provided at a central portion of the bottom surface 1b of the casing 1. The photo sensor 8 detects the amount of light corresponding to each of the R, G, and B colors. As shown in Fig. 3, the scattering portion 61 of the reflecting plate 6 is provided with holes 6 丨 & required for light to enter the photo sensor 8. As shown in FIG. 1, the feedback circuit of the control device connected to the 9-series and the photo sensor 8 calculates the color and the color of the mixed color (white) of each color according to the amount of light detected by the photo sensor 8. 'Control the current, voltage or ratio of the input point source 4 (the ratio of current to voltage 0N/0FF). A liquid crystal display panel (not shown) or the like as a display element is disposed on the light exit surface of the flat light source device constructed as described above. After the light from the flat light source reaching the liquid crystal display panel is modulated according to the image signal, the colors of R, G, and B are displayed. The operation of the flat light source device of the first embodiment will be described below using Fig. 4 . The light emitted from the point light source 4 disposed on both sides of the casing 1 is incident on the deflecting angle element 5 directly or via the reflector 7. The deflecting angle element 5 refracts the incident light toward the reflecting plate 6 side. The light emitted from the deflecting element 5 is reflected by the reflecting plate 6, and then incident on the diffusing plate 2, diffused by the diffusing plate 2, or incident on the reflecting plate 6 from the diffusing plate 2, and then reflected and incident on the diffusing plate 2. Then, the three colors of light of R, G, and B emitted from the point source* are repeatedly incident and reflected between the diffusing plate 2 and the reflecting plate 6, and mixed, and diffused by the white light on the diffusing plate 2. As shown in Fig. 1, the light sensor 8 detects the respective amounts of light, r, G, and B of the white light after the color mixing, and transmits the detected light amounts of R, G, and B to the feedback circuit 9. The feedback circuit 9 detects the amount of light of each of G and B detected by the photo sensor 8.

1260446

The predetermined amount of light comparison 'in the case where the detected amount of light is reduced from the set value' increases the current two voltage or the ratio of the respective point sources 4 of the input R, G, and B according to the amount of decrease. Conversely, in the case where the amount of detected light is increased, the ratio of current, voltage or g of each of the point sources 4 of the input R, G, B is reduced according to the amount of increase. Therefore, the self-diffusion plate 2 can be controlled by the ratio of the current, voltage, and voltage of the input point light source 4 independently of the R, G, and B colors detected by the photo sensor 8. The white illumination that is emitted is kept at the color and brightness of the color. Further, in the flat light source device of the first embodiment, the photo sensor 8 for measuring the amount of light is disposed at a central portion of the bottom surface lb of the casing. This is because the light directly incident on the photo sensor 8 from the deflecting angle element 5 increases as the position of the photo sensor 8 is away from the center portion, and the measurement error increases. That is, as shown in Fig. 4, the photo sensor 8 is disposed in the storage portion 1e provided at a position away from the central portion of the bottom surface lb of the casing 1, and the light R1 from the deflecting member 5 toward the reflecting plate 6 When incident on the photo sensor 8, it is impossible to measure the average (representative) light after the color mixture emitted from the diffusion plate 2. According to the present invention, by arranging the photo sensor 8 in the collecting portion ld provided at the center portion of the bottom surface lb of the casing 1, the average light μ after the color mixing of the diffusing plate 2 can be detected. Thus, by using the correct reference value to control the current, voltage or ratio of the respective point sources 4 of the inputs R, G, B, the desired chromaticity and brightness can be obtained. In addition, in the first embodiment, the photo sensor 8 is disposed at a central portion, but it is only required to detect the average light diffused by the diffusing plate 2. Further, by arranging the hole 6丨a provided in the reflecting plate 6 as the minimum size required for the light sensor 8 to detect light, the chromaticity of the flat light source device can be eliminated.

1260446 (6) and the influence of brightness The sensor 8 uses a photodiode as a photosensitive element, and a band pass chopper corresponding to the wavelengths of R, G, and B is disposed before the photodiode (not shown) ) or a light absorbing color filter (not shown). Further, it is preferable to have a spectral sensitivity close to the visibility characteristic on the color chopper. The point light source 4 of R, G, and B has a luminous efficiency = compared with a point source that emits white light, and the red, green, and blue transmission characteristics of the luminescence spectrum and the color filter used in the flat light source device are utilized. In accordance with the point light source 4, a display device with high color reproducibility can be obtained. Also, the white product can be arbitrarily changed. The reflecting plate may be disposed on the side surface 丨g of the inner side of the light source of the housing 1 so that the light is reflected inside and then diffused toward the diffusing plate 2. By reflecting the inside of the casing i with a reflective material or a white paint, the reflection efficiency of the light emitted from the point light source 4 can be improved. The diffusion plate 2 processes the surface into a rough surface by mixing a reflective material such as a polyethylene terephthalate (PET), an acrylic (PMMA) or a polycarbonate (PC) resin plate or a glass plate. A large light source device having high light diffusibility is obtained. The atomizer 7 can be formed of a resin sheet having a metal layer of silver or a metal material such as silver or aluminum, or a white resin sheet. Further, when the reflectance of the reflecting plate 6 and the reflector 7 is set to 9 〇% or more, the reflection loss on the reflecting surface can be suppressed. Reflector 6 by silver or aluminum

1260446 V. INSTRUCTIONS (7) Meng is = or is formed by vapor deposition of silver or aluminum in a resin sheet. Crying and / h In the first embodiment, the reflecting plate 6 and the reflection are made of different members: 'But the reflecting member 6 and the reflector 7 are integrally formed by the same member, and the basket can be changed to a good θ, and the reflector is reflected. The function of the plate 6 or the reflector 7 is also ok. By reducing the number of parts according to the shape of the 7th, it is possible to improve the workability of the assembly. In order to control the directivity of the emitted light, an optical sheet such as a product 2 or a diffusion sheet may be disposed on the diffusion plate 2. In addition, by using the display in Qiu: Ercheng Mountain has a top angle of about 9 inches. The lens piece of the continuous triangular prism reflects the part of the self-expanding light toward the diffusing plate 2 side, thereby improving the effect of the diffusing plate 2, and reducing the brightness variation of the reflected light of the reflecting plate 6 and the color of the embodiment 2 A cross-section of a flat light source device according to a second embodiment of the present invention is shown in Fig. 5. Fig. 6 is a portion of the periphery of the photosensor of the flat light source device shown in Fig. 5: Fig. 2; Fig. 6 '(4) and Fig. 6 As shown in the figure, the light sensor 8 is placed on the light-shielding member 1 and the light-shielding member 1 is placed on the light-shielding member 10 to form a pinhole 1 Oa. The other construction is the same as that of the first embodiment. =7/^^' is emitted from the exit surface of the deflecting element 5 on the left side, which is first present in the center portion of the bottom surface lb of the body 1. In the present embodiment, the light R3 is used to shield the light R3 emitted from the deflecting angle element 5 to the illuminator 8 by the light shielding member 10, so that the light of the human light sensor 8 is restricted. In i, = using the light-shielding member π to limit the self-biasing of the error component directly into the light of the light sensor 8, $$#, ΗΪ + g dry 5 illumination light. First, the correct debt is measured on the average of the diffuser plate. Page 11 2066-6449-PF (N3); Ahddub.p t d 1260446 V. Description of the invention (8) The following 'describes the specific shape of the pinhole 10 a. In Fig. 6, the deflection angle element 5 on the left side is reviewed. The diameter of the pinhole 丨〇a is a1, the depth of the pinhole is dl, and the incident angle of light incident on the photosensor 8 through the pinhole 1〇a is θ (for the bottom surface of the casing 比The angle of the light incident on the pinhole 1〇a through any point pl provided on the pinhole 10a) The range of the incident angle θ of the light incident on the light-sensing light 8 becomes the following equation. 〇° $ 0 $ t an-1 (al/dl ) (ι) Therefore, by adjusting the diameter a1 and the depth dl of the pinhole l〇a, the range of the incident angle 0 of light incident on the photo sensor 8 can be limited. . Here, the distance from the center 〇1 of the diffuser plate 2 to the pinhole 1〇a is hi, and the distance from the uppermost end of the exit surface 5& of the deflecting angle element 5 to the center 〇1 of the diffuser plate 2 is 11. The smallest angle among the incident angles 0 of the light L5 incident from the uppermost end of the deflecting angle element 5 and incident on the pinhole 10a becomes 0=tan^((ll -al/2)/hl) (2) By setting the incident angle at which the light is incident on the photosensor 8 becomes a pinhole 10a which is necessarily below, the light from the deflecting angle element 5 can be shielded. Specifically, the diameter a1 and the depth di of the pinhole 10a are set.

The value is such that the following formula (3) is satisfied. X tan i((ll —al/2)/hl) —tan-Yal/dl) hl/(ll -al/2) Sdl/al dl gal x hl/(ll -a"2) (3) Yu Yu By setting the values of the diameter ai and the depth dl of the pinhole i according to the equation (3), the light that is incident from the deflection angle element 5 and directly incident on the photosensor 8 can be blocked by the light shielding member 1 to limit the error. The light of ingredients. 2066-6449-PF(N3); Ahddub.ptd Page 12 1260446

Further, the angle element 5 (focusing on the left side of the figure 6 on the left side of Fig. 6) is reviewed, but the relationship is also true for the opposite angle element (on the right side of Fig. 6). The degree of freedom in the arrangement position of the photo sensor 8 can be increased by appropriately setting the values of the diameter a1 and the depth d1 of the pinhole l〇a in accordance with the position of the photosensor 8. In addition, the diameters of the respective pinholes 1 〇a of the R, G, and B are different in size, and the 'in the case where the photosensitive elements of the R, G, and B are combined into one photosensor 8' Needle hole 1 〇a can be one. In the other example (variation) of the second embodiment, as shown in Figs. 8(a) and (b), the pinhole 丨〇a provided in the light-shielding member 1 is a slit-shaped pinhole 1 Ob. can. Further, the shape of the hole provided in the light shielding member 1 can be various shapes such as a long hole or a square. The light shielding member can be formed of a material other than black resin or resin. Further, as shown in Fig. 9, a right angle 稜鏡11 may be disposed on the light incident surface of the photo sensor 8. In FIG. 1A, after the deflecting angle element 5 is emitted, the light R4 incident on the incident surface 11a of the right angle 稜鏡 11 at an angle close to a right angle is totally reflected twice after the reflecting surfaces 11 b and 11 c in the right angle 稜鏡 11 are totally reflected. The light sensor 8 is incident on the light sensor 8, but the light R5 incident at a fixed angle or higher is not totally reflected, but is emitted to the outside of the right angle 稜鏡11. Thus, the right angle 11 only guides the light incident on the incident surface 11a to the photosensor 8 at an incident angle within a predetermined range. Further, the range of the incident angle can be controlled in accordance with the refractive index and shape of the right-angled prism 11. According to the present modification, since the right angle 稜鏡11 can be used to guide only the light having the incident angle within the predetermined range to the photosensor 8, the detection accuracy is improved. Example 3

2066-6449-PF(N3); Ahddub.p td Page 13 1260446 V. Description of the Invention (10) FIG. 11 is a cross-sectional view showing a flat light source device according to Embodiment 3 of the present invention. In the first and second embodiments, the photosensor 8 is disposed in the storage portion 1d provided at the center portion of the bottom surface 1b of the casing 1, but the flat light source device of the third embodiment is as shown in FIG. The light sensor 8 is disposed in a space portion 1 f partitioned by a convex portion 6 1 b provided on the reflecting plate 6. The other construction is the same as that of the first embodiment. Further, light is incident on the convex portion 6 lb of the reflecting plate 6 into the incident hole 6 1 c of the photosensor 8. Here, the diameter of the entrance hole 6 1 c is a, the distance from the entrance hole 61c to the photo sensor 8 is d2, and the upper end of the exit surface 5a of the self-biasing angle element 5 is at the center 扩散2 of the diffusion plate 2. The distance is 12, and the distance a2 from the center 〇2 of the diffuser plate 2 to the incident hole 61c is satisfied by setting the diameter a2 of the incident hole 61c and the distance d2 from the incident hole 6ic to the photo sensor 8. The following formula (4) can shield the light that is directly incident on the photo sensor 8 after being emitted from the deflecting angle element 5. D2 ^a2x h2/(12 - a2/2) (4) Thus, the flat light source device of the third embodiment has light disposed in the space portion 1 f formed by providing a convex portion in the central portion of the reflecting plate. The sensor 8 can suppress an increase in the thickness of the entire flat light source device. [Embodiment 4] Fig. 1 is a cross-sectional view showing a flat light source device according to a fourth embodiment of the present invention, and Fig. 13 is a view showing the action of the rod optical element. In the first embodiment, the rod-shaped optical having an approximately trapezoidal cross section in the incident direction of the first sensor 8 is disposed as shown in FIG. 13 'on the bottom surface 121 of the rod-shaped optical element 12 to scatter the incident light; and the incident portion I2d, let light shine into the light

Page 14 1260446 V. Description of the invention (11) Detector 8. The other construction is the same as that of the embodiment 3. Hereinafter, the action of the rod-shaped optical element 12 will be described with reference to Fig. 13. The light of the rod-shaped optical element 12 to the side surface 1 2 c is reflected on the surface of the side surface 12c according to the incident angle, as indicated by the light indicated by E in Fig. 13, or is incident as indicated by the light indicated by FI and F2. Inside the rod-shaped optical element 12, the light F1 incident on the rod-shaped optical element 12 is repeatedly reflected inside the rod-shaped optical element 12, and then incident on the photosensor 8 from the incident portion 12d. On the other hand, the light F2 incident on the rod-shaped optical element 12 enters the scattering portion 1 2e and is scattered at the incident position. Thus, by providing the scattering portion 1 2 e on the bottom surface lb of the rod-shaped optical element 12, the degree of the shell at the central portion of the diffusing plate 2 can be improved. Further, since the light incident on the side surface 1 2 c of the rod-shaped optical element 1 2 is internally reflected as shown by the light F 1 and mixed, and then incident on the photo sensor 8, the average of the diffusion plate 2 can be more accurately detected. Illumination light. Then, in the fourth embodiment, the rod-shaped optical element 1 2 ' in which the incident portion i2d and the scattering portion I2e are formed on the bottom surface lb in the light incident direction of the photo sensor is raised near the central portion of the diffusion plate 2. Brightness, and the illumination of the average of the well-mixed colors can be incident on the photosensor 8, which can be detected more correctly. Further, as shown in Fig. 12, in order to shield the light that has entered the photosensor 8 from the light that has not passed through the diffusing plate 2 from the deflecting element 5, the light blocking member 10 is disposed at the incident portion of the photosensor 8. Therefore, it is more correct to shield the light from the light sensor 8 by the light-shielding member 1 〇 to shield the light having the entrance/angle of the light of the λ2 (4) as the error component. Detects the average illumination. Further, by the fact that the upper surface m of the rod-shaped optical element 12 and the diffusion plate 2 and the bottom surface reflection plate 6 are each in contact with each other, the diffusion plate 2 and the reflection can be maintained.

2066-6449-PF(N3) ; Ahddub.ptd Page 15 1260446 V. INSTRUCTIONS (12) The spacing of the plates 6. Further, the rod-shaped optical element 12 is formed by using a transparent resin such as acryl or a glass-forming diffusing reflection portion 1 2 e to adhere a white reflective sheet or a rough-surfaced silver or I. Further, an emitting portion 1 2 d for removing or not forming a white sheet or silver or aluminum vapor deposition is provided at a position facing the photo sensor 8. [Embodiment 5] Fig. 1 is a plan view showing a schematic configuration of a flat light source device according to a fifth embodiment of the present invention, and Fig. 15 is a cross-sectional view taken along line C-C of Fig. 14. In the embodiment 3', the space portion formed by providing the convex portion 6丨b in the reflecting plate 6

If one photo sensor 8 is disposed, the flat light source device of the fifth embodiment is provided with two photo sensors 8a, 8b at the intermediate portion 1f. Further, when detecting light and light, in order to reduce the influence of light from the light source on the opposite side, two photo sensors 8a and 8b are arranged at predetermined intervals. Other constructions are the same as in Example 3. In the present embodiment 5, the point light source 4d disposed on the upper side of the casing 1 is controlled according to the detected value of the photo sensor 8a, and the point light source disposed on the side 1 is controlled according to the detected value of the photo sensor 8b. 4e. The spot light arranged on the upper side of the casing :: ::, the degree of brilliance is increased, and the brightness is lower than the upper side and the lower chromaticity of the lower diffusing plate 2 of the point light source 4e disposed on the lower side. In the present embodiment, the two photo sensors 8a and 8b are disposed, and the point light source 4d disposed on the upper side and the light source k on the lower side are controlled according to the respective seedlings and rafts. It prevents the brightness fluctuation or color fluctuation caused by the temperature difference between the upper and lower sides, and obtains uniform illumination light. Further, two or more photosensors 8 may be provided. By configuring multiple lights

1260446 ----------------------- V. Description of the invention (13) The sensor 8 can detect the amount of light more correctly. (Embodiment 6) Fig. 1 is a plan view showing a schematic configuration of a flat light source device according to a sixth embodiment of the present invention, and Fig. 17 is a sectional view taken along line D-D of Fig. 16. In the first embodiment, the point light source 4 is disposed on the side surface of the casing 1. However, as shown in Fig. 17, the point light source 4 may be disposed on the bottom surface 1b of the casing 1. In Fig. 16 and Fig. 17, a first diffusion plate 2 1 for uniformly diffusing incident light is disposed in the opening portion 1a of the casing 1. Further, a second diffusion plate 23 is disposed on the point light source 4 at a predetermined interval from the first diffusion plate 21. The photo sensor 8 is disposed at a central portion of the bottom surface lb of the arrangement point light source 4. The reflecting plate 6 disposed on the bottom surface 1b is provided with an incident hole 61c required for light to enter. Further, a reflection portion 24 for direct light reflection is formed at a position facing the point light source 4 at the position of the second diffusion plate 23 so as to prevent local light from being locally increased due to direct light from the point light source 4. In the flat light source device of the sixth embodiment, the point light source 4 is disposed on the bottom surface of the casing 1 and the first diffusing plate 21 and the diffusing plate 23 are disposed on the point light source 4, so that the light source 4 is emitted from the point light source 4 The light is repeatedly reflected between the two diffusion plates 21, 23 'the light that can be detected by the light sensor 8 after the color mixture is averaged. Further, a embossing plate such as acryl may be used on the second diffusion plate 23. In the above embodiment, the point light source 4 may be a color other than R, G, or B, and is not limited to three colors, and may be two colors or one color. In this case, a photosensor 8 that detects light of a wavelength corresponding to each color is configured. Further, the light source is not limited to the point light source 4 shown in the above embodiment, and for example, a cold cathode tube or an EL (Electro Luminescence) light source may be used. In the case of using such a light source, it is also possible to reduce the specific

2066-6449-PF(N3); Ahddub.ptd Page 17 1260446 V. INSTRUCTIONS (14) The detection light affected by the light source can be properly controlled on the entire flat light source device, and the quality of the display device can be improved. Further, although the liquid crystal display device has been described in the above embodiments, the present invention can be used as a flat light source device, which is printed on a plate having a diffusion function, for example, by disposing a liquid crystal display element on the emitting surface side of the flat light source device. A display device such as a pattern or a character can also be used as another display device such as a kanban or a guide lamp. According to the present invention, the amount of light emitted from the light source is adjusted according to the detected value of the light sensor, especially according to the respective amounts of R, G, and B detected by the light sensor. Independently controlling the current, voltage or ratio of the incident light source source, the white illumination light emitted from the diffusion plate can be maintained at the desired color and brightness.

2066-6449-PF(N3); Ahddub.p td Page 18 1260446 BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view showing a schematic configuration of a flat light source device according to Embodiment 1 of the present invention. Figure 2 is a cross-sectional view taken along line A - A of Figure 1. Figure 3 is a cross-sectional view showing the main part of the line B-B of Figure 1. Fig. 4 is a view for explaining the operation of the flat light source device of the first embodiment of the present invention. Fig. 5 is a cross-sectional view showing a flat light source device according to a second embodiment of the present invention. Fig. 6 is a partial cross-sectional view showing the periphery of the photosensor of the flat light source device shown in Fig. 5. Figure 7 is a cross-sectional view showing a flat light source device according to a second embodiment of the present invention. 8(a) to 8(b) are views showing another example of the light shielding member. Fig. 9 is a view showing an example in which a right angle 稜鏡 is arranged in the light sensor. Figure 10 is a diagram illustrating the effect of a right angle 稜鏡. Figure 11 is a cross-sectional view showing a flat light source device according to a third embodiment of the present invention. Fig. 1 is a cross-sectional view showing a flat light source device according to a fourth embodiment of the present invention. Fig. 1 is a view showing the action of the rod-shaped optical element. Fig. 14 is a plan view showing a schematic configuration of a flat light source device according to a fifth embodiment of the present invention. Figure 15 is a cross-sectional view taken along line C-C of Figure 14.

2066-6449-PF(N3); Ahddub.ptd Page 19 1260446 Brief Description of the Drawings Fig. 1 is a plan view showing a schematic configuration of a flat light source device according to Embodiment 6 of the present invention. Figure 1 is a sectional view taken along line D-D of Figure 16. [Major component symbol description] 1 ~ housing; 1 g ~ side; 2 ~ diffuser; 3 ~ substrate; 4, 4 a, 4 b, 4 c ~ point source; 5 ~ deflection angle element; 6 ~ reflector; 7~reflector; 8~ light sensor; 9~ feedback circuit, 1 0~ shading member; 6 1~ scattering part; 6 2~ regular reflection part.

2066-6449-PF(N3) ;Ahddub.ptd第20页

Claims (1)

1260446 VI. Patent application scope 1. A flat light source device comprising: a housing having an opening; a diffusing plate disposed at the opening to diffuse incident light; a light source disposed in the housing; and a reflecting plate And reflecting light from the light source to the diffusing plate; and the method comprises: a light sensor disposed opposite to the diffusing plate to detect light from the diffusing plate; and a control device according to the light sensor The detected value adjusts the amount of light emitted from the light source. 2. The flat light source device of claim 1, wherein the light source is composed of red, green and blue light sources each emitting red, green and blue light, the light sensor being in accordance with light from the diffuser plate After detecting the red, green, and blue light, the amount of light emitted from the light source is independently adjusted according to the detected value of the light sensor. 3. The flat light source device of claim 1 or 2, wherein a light shielding member is provided to limit a range of incident angles of light incident on the photo sensor. 4. The flat light source device of claim 1 or 2, wherein a right angle 设置 is provided, and light incident at an incident angle within a predetermined range is directed to the photo sensor. 5. A flat light source device comprising: a housing having an opening; a diffuser disposed at the opening to diffuse incident light; 2066-6449-PF(N3); Ahddub.ptd Page 21 1260446 VI. Patent application range A pair of light sources disposed on two sides of the casing; and a reflector for reflecting light from the source to the diffuser The method comprises: two light sensors, the opposite side of the diffusing plate, detecting light from the diffusing plate; and the control device adjusting the light source from the light source according to the detected value of the light sensor Each of the emitted light f ° 6 is a flat light source device as claimed in claim 1, 2 or 5 wherein a rod-shaped optical element is disposed on the photosensor, the rod-shaped optical element having an incident on the bottom surface The scattering portion of the light scattering and the incident portion that causes the light to enter the photosensor. 7. The flat light source device of claim 1, 2 or 5, wherein the photosensor is disposed opposite to a central portion of the diffuser. 8) A flat light source device comprising: a housing having an opening; a pair of diffusing plates disposed at the opening; a light source 'located on a bottom surface of the housing; and a reflector disposed on the bottom surface, reflected from Light emitted by the light source; a light sensor disposed on a bottom surface of the casing to detect light from the diffuser; and a control device for adjusting the amount of light emitted from the light source according to the detected value of the light sensor . 9. The flat light source device of claim 8, wherein the photo sensor is disposed at a central portion of the casing. 2066-6449-PF(N3); Ahddub.ptd Page 22 1260446 2066-6449-PF(N3); Ahddub.ptd Page 23