JP4371733B2 - Surface light source device - Google Patents

Description

  The present invention relates to a planar light source device and a display device including the device. More specifically, the present invention relates to a display device such as a signboard or a guide light using a transmission type liquid crystal display device, a panel displaying characters and designs, and a planar light source device for supplying illumination light to the display device.

  An example of a conventional planar light source device is described in Patent Document 1. In the planar light source device described in Patent Document 1, as shown in FIG. 1 of the publication, the sensor 20 is arranged on the end face 13c of the light guide plate 13 where the LED module 16 is arranged, and the energy of each wavelength band of external light. , And the light emission energy of R (red), G (green), and B (blue) is adjusted based on the detection result.

JP-A-11-260572

  When the LED is used as the light source as in the planar light source device disclosed in Patent Document 1, the following problems occur. That is, since the output of the LED is strongly temperature dependent, there is a problem that chromaticity and luminance change due to a change in ambient temperature. In addition, since such temperature dependency varies depending on the emission colors of R, G, and B, there is a problem that the white balance of the illumination light changes due to a change in ambient temperature. Furthermore, there is a problem that such variation in light emission characteristics occurs between LEDs of the same light emission color. In addition, there is a problem that the life characteristics of the LED are different for each of R, G, and B.

  The present invention has been made in view of the above problems, and a planar light source device capable of automatically correcting changes in chromaticity and luminance of illumination light caused by temperature changes, changes over time, and the like. It aims at providing a display apparatus provided with.

Surface light source device of the present invention comprises a housing having an opening is disposed in the opening, and a diffusion plate that diffuses incident light, provided on both opposite sides of the housing, red, green , a planar light source device comprising a plurality of light sources for emitting light of blue, respectively, and a reflecting plate for the light from the light source to reflections toward the diffusion plate, the housing facing the diffuser plate disposed in the central portion of the bottom surface, on the basis of the red, green, blue light reflected from the diffusion plate, an optical sensor for detecting light, based on the detected value of the light sensor, output from the light source A rod-shaped optical element having a control means for independently adjusting the amount of incident light for each of the red, green and blue colors, a diffuse reflection part for irregularly reflecting incident light, and an incident part for making light incident on the optical sensor on the bottom surface Is arranged on the optical sensor .

  According to the present invention, the amount of light emitted from the light source is adjusted based on the detection value of the light sensor, and in particular, the light is input to the point light source according to the R, G, and B light amounts detected by the light sensor. By controlling the current, voltage, or duty ratio independently for each color of R, G, and B, white illumination light emitted from the diffusion plate can be maintained at a desired chromaticity and luminance.

  Embodiments of a planar light source device and a display device including the device according to the present invention will be described below with reference to the drawings. In addition, what attached | subjected the same code | symbol in each figure has shown the substantially same component.

Embodiment 1
Hereinafter, the planar light source device of the present invention will be described in detail with reference to the drawings. 1 is a plan view showing a schematic configuration of a planar light source device according to Embodiment 1 of the present invention, FIG. 2 is a cross-sectional view taken along line AA in FIG. 1, and FIG. 3 is a main portion taken along line BB in FIG. It is sectional drawing. 1-3, 1 is a housing | casing which has the opening part 1a. A diffusing plate 2 for uniformly diffusing incident light is disposed in the opening 1 a of the housing 1. Reference numeral 4 denotes a plurality of point light sources composed of light emitting diodes (hereinafter referred to as LEDs), a point light source 4a that emits red (R) light, and a point light source 4b that emits light to green (G). And a point light source 4c for emitting blue (B) light. Further, as the point light source 4, a laser diode (Laser Diode: LD) or the like can be used in addition to the LED. A plurality of point light sources 4 are arranged on the substrate 3 along the inner side surface 1 c in the vertical direction of the housing 1. The number of point light sources 4a, 4b and 4c provided on the substrate 3 is set according to the chromaticity of the illumination light and the required luminance. In the planar light source device shown in FIG. 1, they are arranged in a repetitive permutation such as G, B, G, R, G, B. A declination element 5 is disposed at a position where the light from the point light source 4 is emitted. The deflection element 5 has a trapezoidal cross-sectional shape, and refracts the light emitted from the point light source 4 to the reflection plate 6 disposed on the bottom surface 1 b of the housing 1. The reflection plate 6 includes a regular reflection portion 62 that regularly reflects the light incident from the deflection element 5 toward the diffuser plate 2 and an irregular reflection portion 61 that irregularly reflects light. Reference numeral 7 denotes a reflector that surrounds the point light source 4 and reflects light toward the inner wall of the housing 1 out of the light emitted from the point light source 4 toward the deflection element 5. Reference numeral 8 denotes an optical sensor, which is disposed in a storage portion 1 d provided at a substantially central portion of the bottom surface 1 b of the housing 1. The optical sensor 8 detects the amount of light corresponding to each color of R, G, and B. As shown in FIG. 3, a hole 61 a for allowing light to enter the optical sensor 8 is formed in the irregular reflection portion 61 of the reflection plate 6. As shown in FIG. 1, reference numeral 9 denotes a feedback circuit which is a control means connected to the optical sensor 8, and calculates the chromaticity and luminance of each color mixture (white) based on the amount of light detected by the optical sensor 8. The current, voltage, or duty ratio (current / voltage ON / OFF ratio) input to the point light source 4 is controlled.

  A liquid crystal display panel (not shown) or the like is disposed as a display element on the light emitting surface of the planar light source device configured as described above. The light from the planar light source that reaches the liquid crystal panel is modulated based on the video signal, and displays each color of R, G, and B.

  Hereinafter, the operation of the planar light source device according to the first embodiment will be described with reference to FIG.

  Light emitted from the point light source 4 disposed on both side surfaces of the housing 1 enters the deflection element 5 directly or via the reflector 7. The deflection element 5 refracts incident light toward the reflector 6. The light emitted from the deflection element 5 is reflected by the reflecting plate 6 and is incident on the diffusing plate 2 and diffused by the diffusing plate 2 or is incident on the reflecting plate 6 again from the diffusing plate 2 and reflected again. Is incident on the diffusion plate 2. In this way, the light of the three colors R, G, and B emitted from the point light source 4 is incident and reflected between the diffuser plate 2 and the reflector plate 6 to be mixed and diffused as white light by the diffuser plate 2. Is done.

  As shown in FIG. 1, the optical sensor 8 detects the R, G, and B light amounts of the mixed white light, and sends the detected R, G, and B light amounts to the feedback circuit 9. The feedback circuit 9 compares the light amounts of R, G, and B detected by the optical sensor 8 with preset light amounts. If the detected light amount is reduced from a set value, R, R, The current, voltage, or duty ratio input to each point light source 4 of G and B is increased. On the other hand, when the detected light quantity increases, the current, voltage, or duty ratio input to the R, G, B point light sources 4 is lowered according to the increase. In this way, the current, voltage, or duty ratio input to the point light source 4 according to the R, G, and B light amounts detected by the optical sensor 8 is independently controlled for each color of R, G, and B. Thus, the white illumination light emitted from the diffusion plate 2 can be maintained at a desired chromaticity and luminance.

  In the planar light source device according to the first embodiment, the optical sensor 8 for measuring the amount of light is disposed at a substantially central portion of the bottom surface 1 b of the housing 1. This is because as the position of the sensor 8 moves away from the central portion, the measurement error increases due to an increase in the light directly incident on the sensor 8 from the deflection element 5. That is, as shown in FIG. 4, when the optical sensor 8 is arranged in the storage portion 1 e provided at a position away from the central portion of the bottom surface 1 b of the housing 1, the light traveling from the declination element 5 to the reflection plate 6. Since R <b> 1 enters the optical sensor 8, it is not possible to measure mixed (average) light that is emitted from the diffusion plate 2. The present invention can detect the average light R2 mixed in color by the diffusion plate 2 by disposing the optical sensor 8 in the storage portion 1d provided in the substantially central portion of the bottom surface 1b in the housing 1. . In this way, desired chromaticity and luminance can be obtained by controlling the voltage, current, or duty ratio input to the R, G, and B point light sources 4 using accurate reference values.

  In the first embodiment, the optical sensor 8 is disposed substantially at the center, but may be any position as long as the average light diffused by the diffusion plate 2 can be detected.

  Further, the hole 61a provided in the reflecting plate 6 has a minimum size necessary for the light sensor 8 to detect light, thereby eliminating the influence on the chromaticity and luminance unevenness of the planar light source device.

  The optical sensor 8 uses a photodiode as a light receiving element, and a band pass filter (not shown) or a light absorption color filter (not shown) corresponding to the wavelengths of R, G, and B is provided in front of the photodiode. Provided.

  A color filter having a spectral sensitivity characteristic close to the visibility characteristic is preferable.

  The RGB point light source 4 has higher luminous efficiency than a point light source that emits white light, and combines the red, green, and blue transmission characteristics of the color filter used in the liquid crystal display device with the emission spectrum of the point light source 4. Thus, a display device with high color reproducibility can be obtained. Further, the white chromaticity can be arbitrarily changed.

  On the inner side surface 1g where the light source of the housing 1 is not disposed, a reflecting plate may be disposed so as to be reflected on the inner side and directed toward the diffusion plate 2. The reflection efficiency of light emitted from the point light source 4 can also be improved by applying a reflective material, white paint, or the like inside the housing 1.

  The diffusing plate 2 is light diffusing by mixing a reflecting material in a resin plate or glass plate such as polyethylene terephthalate (PET), acrylic (PMMA), or polycarbonate (PC), or by processing the surface into a rough surface. Can be obtained.

  The reflector 7 can be composed of a metal plate having a reflective layer formed of silver or aluminum, a resin sheet deposited with a metal such as silver or aluminum, or a white resin sheet.

  In addition, if the reflectance of the reflecting plate 6 and the reflector 7 is 90% or more, reflection loss on the reflecting surface can be suppressed. The reflector 6 is configured by evaporating aluminum or silver on a metal plate such as aluminum or silver, or a resin sheet.

  In the first embodiment, the reflecting plate 6 and the reflector 7 are configured as separate members, but the reflecting plate 6 and the reflector 7 may be integrally formed from the same member. The housing 1 may also function as the reflecting plate 6 and the reflector 7. By forming in this way, the number of parts can be reduced and the assembly workability can be improved.

  An optical sheet such as a lens sheet or a diffusion sheet may be disposed on the diffusion plate 2 in order to control the directivity of the emitted light. Further, by using a lens sheet in which a triangular prism having a vertical angle of approximately 90 ° is formed on the display surface side, a part of the light emitted from the diffusion plate 2 is reflected to the diffusion plate 2 side, and the light from the diffusion plate 2 is reflected. It is possible to enhance the diffusion effect and reduce luminance unevenness and chromaticity unevenness of the reflected light of the reflecting plate 6.

Embodiment 2
5 is a cross-sectional view of a surface light source device according to Embodiment 2 of the present invention, and FIG. 6 is a partial cross-sectional view of the surface light source device shown in FIG. In the second embodiment, as shown in FIGS. 5 and 6, a light shielding member 10 is provided at the light incident portion of the optical sensor 8. The light shielding member 10 is provided with a pinhole 10a which is a circular hole. Other configurations are the same as those of the first embodiment.

  As shown in FIG. 7, the light emitted from the emission surface 5 a of the left deflection element 5 includes light R <b> 3 that goes to the approximate center of the bottom surface 1 b in the housing 1. In the second embodiment, the light R3 emitted from the deflection element 5 and directed to the optical sensor 8 is blocked by the light shielding member 10, and the light incident on the optical sensor 8 is limited. In this way, by limiting the light directly incident on the optical sensor 8 from the declination element 5 which is an error component by the light shielding member 10, the average illumination light in the diffusion plate 2 can be detected more accurately.

  Hereinafter, a specific shape of the pinhole 10a will be described.

In FIG. 6, attention is paid to the left deflection element 5 for examination. The diameter of the pinhole 10a is a1, the depth of the pinhole is d1, the incident angle of light passing through the pinhole 10a and entering the optical sensor 8 is θ (perpendicular to the bottom surface 1d of the housing 1 and on the pinhole 10a. The angle of the incident angle θ of the light incident on the optical sensor 8 is 0 ° ≦ θ ≦ tan ⁻¹ (a1 / d1) where the angle is an angle with the light incident on the pinhole 10a through an arbitrary point p1 provided. (1)
It becomes. Accordingly, by adjusting the diameter a1 and the depth d1 of the pinhole 10a, the range of the incident angle θ of the light incident on the optical sensor 8 can be limited.

Here, the minimum angle among the incident angles φ of the light L5 emitted from the uppermost end of the deflection element 5 and entering the pinhole 10a is the distance h1 from the center o1 of the diffuser plate 2 to the pinhole 10a. If the distance from the uppermost end of the exit surface 5a of the corner element 5 to the center o1 of the diffusion plate 2 is l1, φ = tan ⁻¹ ((l1−a1 / 2) / h1) (2)
It becomes.

  Therefore, the light from the deflection element 5 can be blocked by designing the pinhole 10a so that the incident angle of the light incident on the optical sensor 8 is not more than φ.

Specifically, the values of the depth d1 and the diameter a1 of the pinhole 10a may be set so as to satisfy the following expression (3).
tan ⁻¹ ((l1−a1 / 2) / h1) ≧ tan ⁻¹ (a1 / d1)
h1 / (l1-a1 / 2) ≦ d1 / a1
d1 ≧ a1 × h1 / (l1-a1 / 2) (3)

  In this way, by setting the values of the depth d1 and the diameter a1 of the pinhole 10a based on the expression (3), the light emitted from the declination element 5 and directly incident on the optical sensor 8 is transmitted by the light shielding member 10. Since it can block | interrupt, the light used as an error component can be restrict | limited. Note that although the study has been made by paying attention to the deflection element 5 on one side (left deflection element in FIG. 6), the same relational expression holds for the opposing deflection element (right side in FIG. 6). As described above, the depth d1 and the diameter a1 of the pinhole 10a are appropriately set in accordance with the position where the optical sensor 8 is disposed, thereby increasing the degree of freedom of the position where the sensor 8 is disposed.

  In addition, the magnitude | size of the diameter a1 of each pinhole 10a of R, G, and B may be a different magnitude | size. Further, when using the optical sensor 8 in which R, G, and B light receiving elements are combined into one, only one pinhole 10a is required.

  As another example (modification) of the second embodiment, as shown in FIGS. 8A and 8B, a pinhole 10a provided in the light shielding member 10 may be a slit-shaped pinhole 10b. Moreover, the shape of the hole provided in the light shielding member 10 can use various shapes, such as a long hole and a square. The light shielding member 10 can be formed of a material other than black resin or resin.

  As shown in FIG. 9, a right-angle prism 11 may be disposed on the light incident surface of the optical sensor 8. In FIG. 10, light R4 emitted from the deflection element 5 and incident at an angle close to a right angle on the incident surface 11a of the right-angle prism 11 is totally reflected twice by the reflection surfaces 11b and 11c in the right-angle prism 11, and the light sensor 8 However, the light R5 incident at a certain angle or more is emitted from the right-angle prism 11 without being totally reflected. Thus, the right-angle prism 11 guides only the light incident on the incident surface 11a to the optical sensor 8 at an incident angle within a predetermined range. The range of the incident angle can be controlled by the refractive index and shape of the right-angle prism 11. According to this modification, only light having an incident angle within a predetermined range is guided to the optical sensor 8 using the right-angle prism 11, so that the detection accuracy is improved.

Embodiment 3
FIG. 11 is a cross-sectional view of a planar light source device according to Embodiment 3 of the present invention. In the first and second embodiments, the optical sensor 8 is disposed in the storage portion 1d provided at the substantially central portion of the bottom surface 1b of the housing 1, but the planar light source device according to the third embodiment is shown in FIG. As shown, the optical sensor 8 is disposed in a space 1 f defined by providing a convex region 61 b on the reflector 6. Other configurations are the same as those of the first embodiment.

In addition, an incident hole 61c through which light enters the optical sensor 8 is provided in the convex region 61b of the reflector. Here, the diameter of the incident hole 61c is a2, the distance from the incident hole 61c to the optical sensor 8 is d2, the distance from the upper end of the exit surface 5a of the deflection element 5 to the center o2 of the diffusing plate 2 is 12, and the diffusing plate 2 When the distance from the center o2 to the incident hole 61c is h2, by setting the diameter a2 of the incident hole 61c and the distance d2 from the incident hole 61c to the optical sensor 8 so as to satisfy the following formula (4), Light that exits from the corner element 5 and directly enters the optical sensor 8 can be blocked.
d2 ≧ a2 × h2 / (l2-a2 / 2) (4)

  Thus, in the planar light source device according to the third embodiment, the optical sensor 8 is arranged in the space portion 1f formed by providing the convex region at the center of the reflecting plate 6, so that the planar light source An increase in the thickness of the entire apparatus can be suppressed.

Embodiment 4
FIG. 12 is a sectional view showing a planar light source device according to Embodiment 4 of the present invention, and FIG. 13 is a diagram for explaining the action of a rod-like optical element. In the fourth embodiment, a rod-shaped optical element 12 having a substantially trapezoidal cross section is disposed in the incident direction of the optical sensor 8. As shown in FIG. 13, the bottom surface 12 b of the rod-shaped optical element 12 is provided with an irregular reflection part 12 e that irregularly reflects incident light and an incident part 12 d that causes light to enter the optical sensor 8. Other configurations are the same as those of the third embodiment.

  Hereinafter, the operation of the rod-shaped optical element 12 will be described with reference to FIG. The light traveling toward the side surface 12c of the rod-shaped optical element 12 is reflected from the side surface 12c like the light shown by E in FIG. 13 depending on the incident angle, or is incident on the inside of the rod-shaped optical element 12 as represented by F1 and F2. To do. The light F1 incident on the rod-shaped optical element 12 is repeatedly reflected inside the rod-shaped optical element 12, and enters the optical sensor 8 from the incident portion 12d. On the other hand, the light F2 incident on the rod-shaped optical element 12 enters the irregular reflection portion 12e and is irregularly reflected at the incident position. Thus, by providing the irregular reflection portion 12e on the bottom surface 12b of the rod-shaped optical element 12, the luminance at the central portion of the diffusion plate 2 can be increased. Further, the light incident on the side surface 12c of the rod-shaped optical element 12 is mixed with the internal reflection repeatedly as in the case of the light F1, and enters the optical sensor 8, so that the average illumination light of the diffusion plate 2 can be detected more accurately. can do.

  As described above, in the fourth embodiment, since the rod-like optical element 12 having the incident portion 12d and the irregular reflection portion 12e formed on the bottom surface 12b is arranged in the light incident direction of the optical sensor 8, the central portion of the diffusion plate 2 is disposed. In addition to increasing the brightness in the vicinity, average illumination light with advanced color mixing can be made incident on the optical sensor 8 and can be detected more accurately.

  Further, as shown in FIG. 12, in order to block light reaching the optical sensor 8 from the deflection element 5 without passing through the diffusion plate 2, the light shielding member 10 is provided at the incident portion of the optical sensor 8. Deploy. As described above, the light having the incident angle close to the horizontal is blocked by the light shielding member 10, and the light incident on the optical sensor 8 from the declination element 5 as an error component without passing through the diffusion plate 2 is limited. Similar to 2, average illumination light can be detected more accurately.

  In addition, the space | interval of the diffuser plate 2 and the reflecting plate 6 can be maintained by arrange | positioning the upper surface 12a of the rod-shaped optical element 12 so that the diffusion plate 2 and the bottom surface 12b may contact | connect the reflecting plate 6, respectively.

  Further, the rod-like optical element 12 is made of a transparent resin such as acrylic or glass, and the diffuse reflection portion 12e on the bottom surface is pasted with a white reflection sheet or processed into a rough surface (uneven surface), and silver or aluminum Is formed by vapor deposition. In addition, a light emitting portion 12d where the white sheet or silver or aluminum vapor deposition is not removed or formed is provided at a position facing the optical sensor 8.

Embodiment 5
14 is a plan view showing a schematic configuration of a planar light source device according to Embodiment 5 of the present invention, and FIG. 15 is a sectional view taken along the line CC of FIG. In the third embodiment, one optical sensor 8 is arranged in the space 1f formed by providing the convex region 61b on the reflecting plate 6. However, in the planar light source device according to the fifth embodiment, Two optical sensors 8a and 8b are arranged in the space 1f. When detecting the light from the light source, the two optical sensors 8a and 8b are arranged at a predetermined interval in order to reduce the influence of the light from the light source on the opposite side. Other configurations are the same as those of the third embodiment.

  In the fifth embodiment, the point light source 4d arranged on the upper side of the casing 1 is controlled based on the detection value of the optical sensor 8a, and the point light source 4e arranged on the lower side is detected by the optical sensor 8b. Control based on the value. Since the temperature of the point light source 4d arranged on the upper side in the housing 1 rises, the luminance is lower than that of the point light source 4e arranged on the lower side, and the chromaticity is also nonuniform on the upper side and the lower side of the diffusion plate 2. In the fifth embodiment, as shown in FIGS. 14 to 15, two optical sensors 8 a and 8 b are arranged, and based on the respective detection values, the point light source 4 d arranged on the upper side and the lower side are arranged. Since the point light source 4e is controlled independently, luminance unevenness and color unevenness due to the temperature difference between the upper and lower sides can be prevented, and uniform illumination light can be obtained.

  Two or more optical sensors 8 may be arranged. By arranging a plurality of optical sensors 8, the amount of light can be detected more accurately.

Embodiment 6
FIG. 16 is a plan view showing a schematic configuration of a planar light source device according to Embodiment 6 of the present invention, and FIG. 17 is a cross-sectional view taken along the line DD of FIG. In the first embodiment, the point light source 4 is disposed on the side surface of the housing 1, but the point light source 4 may be disposed on the bottom surface 1 b of the housing 1 as shown in FIG. 17. 16 and 17, a first diffusion plate 21 that uniformly diffuses incident light is disposed in the opening 1 a of the housing 1. A second diffusion plate 23 is disposed on the point light source 4 at a predetermined interval so as to face the first diffusion plate 21. The optical sensor 8 is disposed at a substantially central portion of the bottom surface 1b on which the point light source 4 is disposed. The reflecting plate 6 disposed on the bottom surface 1 b is provided with an incident hole 61 c for allowing light to enter the optical sensor 8. In addition, in the position facing the point light source 4 of the second diffusing plate 23, in order to prevent the brightness from being locally increased by the direct light from the point light source 4, a reflection part 24 that reflects the direct light is formed. ing.

  In the planar light source device according to the sixth embodiment, the point light source 4 is arranged on the bottom surface of the housing 1, and the first diffusion plate 21 and the second diffusion plate 23 are arranged on the point light source 4. By repeatedly reflecting the light emitted from the point light source 4 between the two diffusing plates 21 and 23 and the reflecting plate 6, the mixed average light can be detected by the optical sensor 8.

  Note that a transparent plate such as acrylic can also be used as the second diffusion plate 23.

  In the above embodiment, the point light source 4 may be a color other than R, G, and B, and is not limited to three colors, and may be two colors or one color. In this case, an optical sensor 8 that can detect light having a wavelength corresponding to each color is disposed.

  Furthermore, the light source is not limited to the point light source 4 shown in the above-described embodiment, and may be a light source using a cold cathode tube or EL (electroluminescence), for example. Even when such a light source is used, it is possible to detect light with less influence from a specific light source, and the entire planar light source device can be accurately controlled, and the quality of the display device Improvements can be made.

  In the above-described embodiment, the liquid crystal display device has been described. However, the present invention can be used as a planar light source device, and a display means other than the liquid crystal display element, for example, a pattern or characters on a plate having a diffusion function. By arranging the printed one on the exit surface side of the planar light source device, it can be used as another display device such as a signboard or a guide light.

It is a top view which shows schematic structure of the planar light source device concerning Embodiment 1 of this invention. It is the sectional view on the AA line of FIG. It is principal part sectional drawing of the BB line of FIG. It is a figure explaining operation | movement of the planar light source device concerning Embodiment 1 of this invention. It is sectional drawing which shows the planar light source device concerning Embodiment 2 of this invention. It is a fragmentary sectional view in the optical sensor periphery of the planar light source device shown in FIG. It is sectional drawing explaining the planar light source device concerning Embodiment 2 of this invention. It is a figure which shows the other example of a light shielding member. It is a figure which shows the example which arrange | positions a right-angle prism in a light sensor. It is a figure explaining the effect | action of a right-angle prism. It is sectional drawing which shows the planar light source device concerning Embodiment 3 of this invention. It is sectional drawing which shows the planar light source device concerning Embodiment 4 of this invention. It is a figure explaining the effect | action of a rod-shaped optical element. It is a top view which shows schematic structure of the planar light source device concerning Embodiment 5 of this invention. It is CC sectional view taken on the line of FIG. It is a top view which shows schematic structure of the planar light source device concerning Embodiment 6 of this invention. It is the DD sectional view taken on the line of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Housing | casing 1a Opening part 1b Bottom face 2 Diffusion plate 3 Substrate 4 Point light source 5 Deflection element 6 Reflection plate 7 Reflector 8 Optical sensor 9 Feedback circuit 10 Light shielding member 10a Pinhole 11 Right angle prism 12 Rod-like optical element 21 First diffusion plate 23 Second diffuser 24 Reflector

Claims (1)

A housing having an opening, a diffuser plate disposed in the opening for diffusing incident light, and a plurality of light sources that emit red, green, and blue light respectively provided on opposite side surfaces of the housing. A planar light source device comprising: a light source; and a reflective plate that reflects light from the light source toward the diffuser plate, and is disposed in a central portion of the bottom surface of the casing facing the diffuser plate, An optical sensor that detects light based on red, green, and blue light reflected from the diffuser plate, and an amount of light emitted from the light source based on a detection value of the optical sensor, A control unit that adjusts independently for each color, a diffused reflection part that diffusely reflects incident light, and a rod-shaped optical element that has an incident part on the bottom for making light incident on the optical sensor are arranged on the optical sensor. A planar light source device.

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