JP2008198404A - Lighting system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lighting system with luminance of irradiation light improved. <P>SOLUTION: The lighting system (a backlight unit) 10 is provided with a light guide plate equipped with a light-incident face (a given side-end face) 4a and a light-irradiating face (a front face) 4b, LEDs 2 each with a luminous face 2a fitted to the vicinity of, and arranged so as to be opposed to, the light-incident face 4a of the light guide plate 4, and a reflecting plate 3 at least equipped with reflecting parts 3a, 3b covering a side-end face 4c and a rear face 4d, respectively, other than the given side-end face of the light guide plate 4. The reflecting plate 3 is further provided, in addition to the reflecting parts 3a, 3b, with a reflecting plate 3c covering a given area of the light-incident face 4a of the light guide plate 4, and at the same time, the reflecting parts 3b, 3c of the reflecting plate 3 are integrally coupled with each other. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a lighting device, and more particularly to a lighting device including a light guide plate.

  2. Description of the Related Art Conventionally, an illumination device including a light guide plate for guiding light generated by an LED (light emitting diode) in a predetermined direction is known (see, for example, Patent Document 1). Patent Document 1 discloses an illumination device (backlight unit) used in a liquid crystal display device.

  6 and 7 are a cross-sectional view and a plan view schematically showing an example of the above-described conventional illumination device (backlight unit) for a liquid crystal display device. 6 and 7, in a conventional lighting device (backlight unit) for a liquid crystal display device, a light guide plate 102, a plurality of LEDs 103, a reflection plate 104, and a plurality of optical sheets are provided in a frame-shaped storage case 101. 105 is stored. In FIG. 7, the plurality of optical sheets 105 are not shown for simplification of the drawing.

  The light guide plate 102 has a light incident surface 102a for introducing light generated by the plurality of LEDs 103, and a light emission surface 102b for emitting light introduced from the light incident surface 102a in the A direction (irradiation direction). And have. The light incident surface 102 a is configured by a predetermined side end surface of the light guide plate 102, and the light emitting surface 102 b is configured by the front surface of the light guide plate 102. In addition, the plurality of LEDs 103 are arranged in the vicinity of the light incident surface 102 a of the light guide plate 102 while being mounted on the same substrate 106. Furthermore, the plurality of LEDs 103 are arranged at predetermined intervals along the light incident surface 102a of the light guide plate 102 so that each light emitting surface 103a faces the light incident surface 102a of the light guide plate 102. . The reflection plate 104 is disposed so as to cover the back surface 102c of the light guide plate 102 opposite to the light emitting surface (front surface) 102b. The plurality of optical sheets 105 include a diffusion sheet, a prism sheet, and the like, and are disposed on the light emitting surface 102b of the light guide plate 102.

  Further, although not shown, a liquid crystal display panel that is irradiated with light emitted from the illumination device (backlight unit) is disposed on the optical sheet 105 positioned on the forefront side of the plurality of optical sheets 105.

  Then, when light generated by the plurality of LEDs 103 is introduced from the light incident surface 102a of the light guide plate 102, the light is guided from the light incident surface 102a of the light guide plate 102 to the light emitting surface 102b and is directed in the A direction (irradiation). Direction). Thereafter, the light emitted in the A direction (irradiation direction) from the light emission surface 102b of the light guide plate 102 passes through the plurality of optical sheets 105 and irradiates a liquid crystal display panel (not shown).

  In the conventional illumination device (backlight unit) shown in FIGS. 6 and 7, when light is emitted from the back surface 102 c of the light guide plate 102, the light is reflected toward the light guide plate 102 by the reflection plate 104. . For this reason, even if light is emitted from the back surface 102 c of the light guide plate 102, the light can be reintroduced into the light guide plate 102. That is, in the conventional illuminating device (backlight unit) shown in FIGS. 6 and 7, it is possible to suppress a decrease in light use efficiency due to light being emitted from the back surface 102 c of the light guide plate 102. Become.

  Conventionally, in the configuration shown in FIGS. 6 and 7, a lighting device (not shown) further including a reflecting plate (not shown) covering a side end surface other than the light incident surface (predetermined side end surface) 102 a of the light guide plate 102. A backlight unit) is also known.

JP 2006-309103 A

  However, in the conventional illumination device (backlight unit) shown in FIGS. 6 and 7, when light (L100 in FIG. 7) is emitted from a predetermined region of the light incident surface 102a of the light guide plate 102, the light is emitted. It is difficult to re-introduce the light into the light guide plate 102. For this reason, in the conventional illuminating device (backlight unit) shown in FIGS. 6 and 7, the light use efficiency is reduced due to the light being emitted from the predetermined region of the light incident surface 102a of the light guide plate 102. The inconvenience of lowering occurs. As a result, there is a problem that it is difficult to improve the luminance of the emitted light from the illumination device (backlight unit).

  This invention was made in order to solve the above problems, and the objective of this invention is to provide the illuminating device which can improve the brightness | luminance of emitted light.

  In order to achieve the above object, an illumination device according to one aspect of the present invention includes a light incident surface for introducing light, and a light emission surface for emitting light introduced from the light incident surface in an irradiation direction. A light source plate having a light emitting surface provided near the light incident surface of the light guide plate and disposed to face the light incident surface of the light guide plate, and a light incident surface and a light output surface of the light guide plate Includes a reflector having at least a first reflector that covers different surfaces. In addition to the first reflecting portion, the reflecting plate further includes a second reflecting portion that covers a predetermined region of the light incident surface of the light guide plate, and the first reflecting portion and the second reflecting portion of the reflecting plate include Are integrally connected to each other.

  In the illumination device according to this aspect, as described above, in addition to the first reflecting portion that covers a surface different from the light incident surface and the light exit surface of the light guide plate, the first region that covers a predetermined region of the light incident surface of the light guide plate. By using the reflection plate further including the two reflection portions, the light emitted from the predetermined region of the light incident surface of the light guide plate can be reflected toward the light guide plate by the second reflection portion of the reflection plate. Therefore, in addition to light emitted from a surface different from the light incident surface and the light emitting surface of the light guide plate, light emitted from a predetermined region of the light incident surface of the light guide plate can be reintroduced into the light guide plate. Thereby, in addition to being able to suppress a decrease in light use efficiency due to light being emitted from a surface different from the light incident surface and the light emitting surface of the light guide plate, in addition to the light incident surface of the light guide plate It is also possible to suppress a decrease in light use efficiency due to light being emitted from the predetermined region. As a result, the brightness of the emitted light from the lighting device can be improved.

  In the illumination device according to one aspect, as described above, the first reflecting portion and the second reflecting portion of the reflecting plate are integrally connected to each other to be emitted from a predetermined region of the light incident surface of the light guide plate. There is no need to separately prepare a reflecting member for reflecting the reflected light. Thereby, the number of parts can be reduced.

  In the illumination device according to the above aspect, preferably, the distance from the light incident surface of the light guide plate to the second reflecting portion of the reflective plate is smaller than the distance from the light incident surface of the light guide plate to the light emitting surface of the light source. With this configuration, even if the light reflected by the second reflecting portion of the reflecting plate is scattered in multiple directions, the distance from the light incident surface of the light guide plate to the second reflecting portion of the reflecting plate is small. It is possible to suppress a decrease in the amount of light reintroduced into the light incident surface of the light plate.

  In the illumination device according to the above aspect, preferably, a plurality of light sources are provided at predetermined intervals along the light incident surface of the light guide plate, and the second reflection portion of the reflection plate includes two adjacent light sources. One is arranged in each of the regions between the light sources. If comprised in this way, in the illuminating device with which the several light source was arranged at predetermined intervals along the light-incidence surface of the light-guide plate, the brightness | luminance of the emitted light from an illuminating device can be improved easily. it can.

  In the illumination device according to the above aspect, the second reflecting portion of the reflecting plate is preferably configured to be able to bias a predetermined region of the light incident surface of the light guide plate. If comprised in this way, since the predetermined area | region of the light-incidence surface of a light-guide plate can be urged | biased by the 2nd reflection part of a reflecting plate, the shakiness of a light-guide plate can be suppressed. Thereby, generation | occurrence | production of the abnormal noise resulting from the shakiness of a light-guide plate can be suppressed.

  In this case, preferably, the second reflecting portion of the reflecting plate is bent so as to be elastically deformable. If comprised in this way, the predetermined area | region of the light-incidence surface of a light-guide plate can be easily urged | biased with the elastic force which generate | occur | produces in the 2nd reflection part of a reflecting plate.

  As described above, according to the present invention, it is possible to easily obtain an illuminating device capable of improving the luminance of emitted light.

  FIG. 1 is a perspective view showing a structure of a liquid crystal display device using a backlight unit according to an embodiment of the present invention. FIG. 2 is an exploded perspective view of the liquid crystal display device (backlight unit) shown in FIG. FIG. 3 is a cross-sectional view of the liquid crystal display device (backlight unit) shown in FIG. 4 and 5 are a plan view and a perspective view for explaining in detail the structure of the reflector of the backlight unit according to the embodiment of the present invention. First, the structure of the backlight unit (illumination device) and the liquid crystal display device using the backlight unit according to the present embodiment will be described with reference to FIGS.

  The liquid crystal display device using the backlight unit (illumination device) 10 of the present embodiment is used in a state where the backlight unit 10 is installed on the back side of the liquid crystal display panel 20 as shown in FIGS. The And the backlight unit 10 of this embodiment is comprised so that planar light can be radiate | emitted to A direction (irradiation direction).

  As a specific structure, as shown in FIGS. 2 and 3, the backlight unit 10 of this embodiment includes a back side case (backlight case) 1, a plurality of LEDs (light emitting diodes) 2, and a reflector. 3, a light guide plate 4, a plurality of optical sheets 5, and a front case (bezel) 6. The LED 2 is an example of the “light source” in the present invention.

  The back side case 1 has four side parts 1a connected in a frame shape, and a bottom part 1b that closes the opening of the frame body constituted by the four side parts 1a from the back side. The plurality of LEDs 2, the reflection plate 3, the light guide plate 4, and the plurality of optical sheets 5 are stored in a region (storage region) surrounded by the four side portions 1 a of the back side case 1. Specifically, the plurality of LEDs 2 are attached to the inner surface of a predetermined side portion 1a (1c) of the four side portions 1a of the back side case 1. Further, the reflection plate 3, the light guide plate 4, and the plurality of optical sheets 5 are sequentially placed on the bottom 1 b of the back side case 1 in this order. In addition, the back side case 1 may be comprised with the resin molded product, and may be comprised with the metal plate.

  As shown in FIGS. 2 to 4, the plurality of LEDs 2 are arranged in the vicinity of a light incident surface 4 a of the light guide plate 4 described later, and each light emitting surface 2 a is formed on the light incident surface 4 a of the light guide plate 4. The light guide plates 4 are arranged at predetermined intervals along the light incident surface 4a so as to face each other. The plurality of LEDs 2 are mounted on the same FPC (flexible printed wiring board) 7. The FPC 7 on which the plurality of LEDs 2 are mounted is bonded to the inner surface of a predetermined side portion 1a (1c) of the back side case 1 via a double-sided tape 8. In the present embodiment, a heat dissipation sheet may be interposed between the FPC 7 and the predetermined side 1a (1c) of the back side case 1. If comprised in this way, the radiation | emission of the heat | fever which generate | occur | produces in LED2 can be performed efficiently. Further, the FPC 7 may be screwed to a predetermined side 1a (1c) of the back side case 1.

  Moreover, the reflecting plate 3 is comprised by the plate-shaped member (For example, metal plates, such as an aluminum plate) which can reflect light. The reflection plate 3 includes a side portion (hereinafter referred to as a reflection portion 3a) that covers a side end surface 4c of the light guide plate 4 described later, and a bottom portion (hereinafter referred to as a reflection portion 3b) that covers the back surface 4d of the light guide plate 4. Have at least. That is, the reflection portion 3 a of the reflection plate 3 is disposed along the side end surface 4 c of the light guide plate 4, and the reflection portion 3 b of the reflection plate 3 is disposed along the back surface 4 d of the light guide plate 4. The reflecting portions 3a and 3b are examples of the “first reflecting portion” in the present invention.

  The light guide plate 4 is made of a transparent member made of a transparent resin or the like. The light guide plate 4 includes a light incident surface 4a for introducing light generated by the plurality of LEDs 2 and a light emission surface for emitting light introduced from the light incident surface 4a in the A direction (irradiation direction). 4b. The light incident surface 4 a is configured by a predetermined side end surface (side end surface on the LED 2 side) of the light guide plate 4, and the light emitting surface 4 b is configured by the front surface of the light guide plate 4.

  The light guide plate 4 also has a side end surface 4c and a back surface 4d different from the light incident surface (predetermined side end surface) 4a and the light emitting surface (front surface) 4b. By the way, when light is emitted from the side end surface 4c and the back surface 4d of the light guide plate 4, unless the light is collected, the light use efficiency is lowered. In the present embodiment, even if light is emitted from the side end surface 4 c and the back surface 4 d of the light guide plate 4, the light can be reflected toward the light guide plate 4 by the reflection portions 3 a and 3 b of the reflection plate 3. For this reason, even if light is emitted from the side end surface 4c and the back surface 4d of the light guide plate 4, the light can be reintroduced into the light guide plate 4, so that the light is transmitted from the side end surface 4c and the back surface 4d of the light guide plate 4. It is possible to suppress a decrease in light utilization efficiency due to the emission. The side end surface 4c and the back surface 4d are examples of “a surface different from the light incident surface and the light emitting surface” in the present invention.

  Here, in this embodiment, as shown in FIGS. 2 to 5, the reflector 3 emits light emitted from a predetermined region of the light incident surface 4 a of the light guide plate 4 in addition to the reflection portions 3 a and 3 b described above. Is further reflected to the light guide plate 4. Specifically, the reflecting portion 3c of the reflecting plate 3 is integrally connected to the reflecting portion (bottom portion) 3b, and the connecting portion 3d between the reflecting portion 3b and the reflecting portion 3c is guided by the reflecting portion 3c. The light plate 4 is bent so as to be disposed along a predetermined region of the light incident surface 4a. For this reason, the predetermined area | region of the light-incidence surface 4a of the light-guide plate 4 is the state covered with the reflection part 3c of the reflecting plate 3. FIG. In the present embodiment, the distance from the light incident surface 4a of the light guide plate 4 to the reflecting portion 3c of the reflector 3 is smaller than the distance from the light incident surface 4a of the light guide plate 4 to the light emitting surface 2a of the LED 2. Yes.

  In the present embodiment, a plurality of reflecting portions 3 c of the reflecting plate 3 are provided, and the plurality of reflecting portions 3 c of the reflecting plate 3 are arranged at predetermined intervals along the arrangement direction of the LEDs 2. Has been. A plurality of reflecting portions 3 c of the reflecting plate 3 are arranged one by one in each of the regions 10 a between two adjacent LEDs 2. That is, a region (predetermined region) corresponding to the region 10 a of the light incident surface 4 a of the light guide plate 4 is covered by the reflection portion 3 c of the reflection plate 3.

  Furthermore, in the present embodiment, the reflecting portion 3 c of the reflecting plate 3 is configured to be able to bias a region (predetermined region) corresponding to the region 10 a of the light incident surface 4 a of the light guide plate 4. Specifically, the reflecting portion 3c of the reflecting plate 3 is folded in half so as to be elastically deformable. And the area | region (predetermined area | region) corresponding to the area | region 10a of the light-incidence surface 4a of the light-guide plate 4 is urged | biased by the B direction with the elastic force which generate | occur | produces in the reflection part 3c of the reflecting plate 3. FIG. The B direction described above is a direction perpendicular to the light incident surface 4 a of the light guide plate 4 and a direction in which the light incident surface 4 a of the light guide plate 4 is separated from the light emitting surface 2 a of the LED 2.

  Further, as shown in FIGS. 2 and 3, the plurality of optical sheets 5 are provided for diffusing light emitted from the light emitting surface 4 b of the light guide plate 4. The plurality of optical sheets 5 include, for example, a diffusion sheet and a prism sheet. Moreover, the optical sheet 5 located on the forefront side among the plurality of optical sheets 5 is bonded to the inner surface of a lid portion 6b of the front side case 6 described later via a double-sided tape (not shown). .

  The front case 6 includes four side portions 6a connected in a frame shape, and a frame-shaped lid portion 6b that closes a part of the opening of the frame body constituted by the four side portions 6a from the front side. have. The front side case 6 is fixed to the back side case 1 by attaching each of the four side parts 6 a to the four side parts 1 a of the back side case 1. In the state where the front side case 6 is fixed to the back side case 1, the front surface of the optical sheet 5 located on the foremost side of the plurality of optical sheets 5 is the lid portion 6 b of the front side case 6. It is exposed through the opening 6c. In addition, the front side case 6 may be comprised with the resin molded product, and may be comprised with the metal plate.

  The liquid crystal display panel 20 installed on the front side of the backlight unit 10 has a double-sided tape (not shown) on the lid 6b of the front case 6 so as to close the opening 6c of the lid 6b of the front case 6. Z)). The liquid crystal display panel 20 includes a pair of substrates 21 and 22 that sandwich a liquid crystal layer (not shown), a front side polarizing plate 23, a back side polarizing plate 24, and the like.

  In the liquid crystal display device described above, when light generated by the plurality of LEDs 2 is introduced from the light incident surface 4a of the light guide plate 4, the light is guided from the light incident surface 4a of the light guide plate 4 to the light emitting surface 4b. The light is emitted in the A direction (irradiation direction). Thereafter, the light emitted from the light exit surface 4 b of the light guide plate 4 in the A direction (irradiation direction) passes through the plurality of optical sheets 5 and irradiates the liquid crystal display panel 20.

  In the present embodiment, as described above, in addition to the reflecting portions 3a and 3b covering the side end surface (side end surface other than the predetermined side end surface functioning as the light incident surface 4a) 4c and the back surface 4d of the light guide plate 4, the light guide plate 4 is guided. By using the reflecting plate 3 further having the reflecting portion 3c covering the predetermined area of the light incident surface 4a of the light plate 4, the light is emitted from the predetermined area of the light incident surface 4a of the light guide plate 4 by the reflecting portion 3c of the reflecting plate 3. Light can be reflected toward the light guide plate 4. Therefore, in addition to the light emitted from the side end surface 4 c and the back surface 4 d of the light guide plate 4, the light emitted from the predetermined region of the light incident surface 4 a of the light guide plate 4 can be reintroduced into the light guide plate 4. Thereby, in addition to being able to suppress a decrease in light utilization efficiency due to light being emitted from the side end surface 4c and the back surface 4d of the light guide plate 4, a predetermined region of the light incident surface 4a of the light guide plate 4 can be suppressed. It is also possible to suppress a decrease in light use efficiency due to light being emitted from. As a result, the brightness of the emitted light from the backlight unit 10 can be improved.

  Further, in the present embodiment, as described above, the light emitted from the predetermined region of the light incident surface 4a of the light guide plate 4 is reflected by integrally connecting the reflection portions 3b and 3c of the reflection plate 3 to each other. There is no need to separately prepare a reflecting member for the purpose. Thereby, the number of parts can be reduced.

  In the present embodiment, as described above, the distance from the light incident surface 4a of the light guide plate 4 to the reflecting portion 3c of the reflective plate 3 is the distance from the light incident surface 4a of the light guide plate 4 to the light emitting surface 2a of the LED 2. Since the distance from the light incident surface 4a of the light guide plate 4 to the reflection portion 3c of the reflection plate 3 is small even if the light reflected by the reflection portion 3c of the reflection plate 3 is scattered in multiple directions. The amount of light re-introduced into the light incident surface 4a of the light guide plate 4 can be suppressed from decreasing.

  In the present embodiment, as described above, the light guide plate 4 is configured such that the reflection portion 3c of the reflection plate 3 is configured to be able to bias a predetermined region of the light incident surface 4a of the light guide plate 4. Since the predetermined region of the light incident surface 4a can be urged by the reflecting portion 3c of the reflecting plate 3, the shading of the light guide plate 4 can be suppressed. Thereby, generation | occurrence | production of the unusual noise resulting from the shakiness of the light-guide plate 4 can be suppressed.

  In the present embodiment, as described above, the light guide plate 4 can be easily bent by the elastic force generated in the reflection portion 3c of the reflection plate 3 by bending the reflection portion 3c of the reflection plate 3 so as to be elastically deformable. A predetermined area of the light incident surface 4a can be biased.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiment but by the scope of claims for patent, and includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

  For example, in the above-described embodiment, an example in which the present invention is applied to a backlight unit (illumination device) used in a liquid crystal display device has been described. However, the present invention is not limited thereto, and illumination used in devices other than the liquid crystal display device. It is also applicable to the device.

  In the above embodiment, a plurality of LEDs are provided. However, the present invention is not limited to this, and the number of LEDs may be one.

1 is a perspective view illustrating a structure of a liquid crystal display device using a backlight unit according to an embodiment of the present invention. It is a disassembled perspective view of the liquid crystal display device (backlight unit) shown in FIG. It is sectional drawing of the liquid crystal display device (backlight unit) shown in FIG. It is a top view for demonstrating in detail the structure of the reflecting plate of the backlight unit by one Embodiment of this invention. FIG. 4 is a perspective view for explaining in detail the structure of a reflector of a backlight unit according to an embodiment of the present invention. It is sectional drawing which showed simply an example of the conventional illuminating device (backlight unit) for liquid crystal display devices. It is the top view which showed simply an example of the illuminating device (backlight unit) for the conventional liquid crystal display device.

Explanation of symbols

2 LED (light source)
2a Light emitting surface 3 Reflector 3a, 3b Reflector (first reflector)
3c Reflector (second reflector)
4 light guide plate 4a light incident surface 4b light emitting surface 4c side end surface (surface different from light incident surface and light emitting surface)
4d rear surface (a surface different from the light incident surface and the light output surface)
10 Backlight unit (lighting device)
10a area

Claims (5)

A light guide plate having a light incident surface for introducing light and a light emission surface for emitting light introduced from the light incident surface in an irradiation direction;
A light source having a light emitting surface provided in the vicinity of the light incident surface of the light guide plate and arranged to face the light incident surface of the light guide plate;
A reflector having at least a first reflector that covers a surface different from the light incident surface and the light exit surface of the light guide plate;
In addition to the first reflecting portion, the reflecting plate further includes a second reflecting portion that covers a predetermined region of the light incident surface of the light guide plate, and the first reflecting portion and the second reflecting portion of the reflecting plate. The lighting device is characterized in that the sections are integrally connected to each other.   The distance from the light incident surface of the light guide plate to the second reflecting portion of the reflector is smaller than the distance from the light incident surface of the light guide plate to the light emitting surface of the light source. Lighting equipment. A plurality of the light sources are provided at predetermined intervals along the light incident surface of the light guide plate,
3. The lighting device according to claim 1, wherein one second reflecting portion of the reflecting plate is disposed in each of the regions between the two adjacent light sources.   The second reflecting portion of the reflecting plate is configured to be able to bias a predetermined region of the light incident surface of the light guide plate. Lighting device.   The lighting device according to claim 4, wherein the second reflecting portion of the reflecting plate is bent so as to be elastically deformable.

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