JP2007165064A - Lighting system and display using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a direct lighting system having improved luminance distribution, and to provide a liquid crystal display using the direct lighting system. <P>SOLUTION: The lighting system comprises a plurality of LED light sources arranged on a circuit board; and a light guide plate for guiding the light of LED light sources entering from an incident surface to an irradiation surface at a side opposite to the incident surface as illumination light. The light guide plate comprises an upper light guide plate and a lower one having different quality each. A recess for guiding light emitted from each LED light source to the inside of the light guide plate is formed on the lower light guide plate, and the LED light source is arranged near the opening surface of the recess. Further, a fine prism structure for emitting light inside the light guide plate onto the surface is formed on each surface of the upper and lower light guide plates. By utilizing the three points, namely difference in quality, a recessed shape, and a fine prism, a luminous surface having more uniform luminance distribution can be obtained. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an illumination device that illuminates a non-self-luminous display element, and a display device used in an electronic apparatus. In particular, the present invention relates to a liquid crystal display device used for a portable information device, a mobile phone, a liquid crystal television, and the like.

  Liquid crystal display devices that can obtain high-definition color images with low power consumption are often used for display devices used in recent mobile phones and mobile computers. Since the liquid crystal element used in the liquid crystal display device is a non-self-luminous type, the liquid crystal element is illuminated using an illumination device that uses a high-intensity white LED as a light source.

On the other hand, backlights using LED light sources are also being used in medium and large-sized liquid crystal display devices. As a backlight using an LED light source, a sidelight type backlight that introduces light from the side surface of the backlight has been widely used as in a small liquid crystal display device, but the number of LED light sources used as the illumination screen becomes larger Hundreds of things have appeared. In order to illuminate medium- and large-sized liquid crystal display elements without using such a large amount of LED light sources, a so-called direct-type illumination device that directly irradiates illumination light from the back of these liquid crystal display elements has been devised. In order to irradiate a wider area with one LED light source, this direct type illumination device has a device in which a light diffusion structure is provided immediately above the LED light source to substantially widen the light irradiation area (for example, , See Patent Document 1).
JP 2004-14365 A

  However, the conventional direct illumination device has a problem that a non-uniform luminance distribution can be obtained because the narrow-width radiated light from the LED light source cannot be efficiently dispersed inside the light guide plate. In addition, the light diffusing structure provided directly above the LED light source is not designed to sufficiently spread narrow radiated light with a short distance from the light emitting surface of the LED light source. However, it has a problem of requiring a large number of LED light sources.

  An object of the present invention is to realize a direct illumination device and a liquid crystal display device using a small LED light source having a good luminance distribution.

  The illumination device of the present invention includes a plurality of LED light sources arranged on a circuit board and a light guide plate arranged on the LED light source side. The light guide plate guides the emitted light from each LED light source. A recess for dispersing inside the light plate is formed, and the LED element is disposed in the vicinity of the opening surface of the recess. Furthermore, the light guide plate is divided into two light guide plates, an upper part and a lower part. A fine prism structure for increasing light extraction efficiency into and out of the light guide plate was formed on the light entrance / exit surface of each light guide plate. In addition, the light reflecting material was disposed so as to cover the light guide plate except for the vicinity of the opening surface of the recess formed in the light guide plate and the final emission surface that is a surface from which light is emitted for illumination purposes. Furthermore, in order to enhance the diffusion effect when light rays from the light source enter the upper light guide plate from the lower light guide plate, materials having different refractive indexes are used for the upper and lower light guide plates.

  With such a configuration, it becomes possible to efficiently guide light from the LED light source into the light guide plate, and as a result, it is possible to improve the visual characteristics and luminance distribution of a display device using this illumination device. .

  In addition, the intersection of the fine prism structures formed in each direction is configured to coincide with the center of each recess. Further, the size of the recess can be set to reach not only the lower light guide plate but also the upper light guide plate. Further, as the shape of the concave portion, a conical shape or a circular arc shape can be used in addition to the spherical shape.

  With such a configuration, it is possible to grasp the area irradiated by the LED light source, and to control the light emission intensity and the luminance distribution, which not only improves the luminance distribution but also reduces the number of LED light sources. This makes it possible to perform efficient lighting.

  Moreover, the illumination device of the present invention is provided so as to face the LED light sources and the plurality of LED light sources arranged on the circuit board, and the light from the LED light sources is incident from the light incident surface and irradiated from the light exit surface. A first light guide plate, and a second light guide plate that receives light from the light exit surface of the first light guide plate and irradiates the light from the irradiation surface. The first light guide plate and the second light guide plate are respectively It is made of materials with different refractive indexes. Furthermore, the light incident surface of the first light guide plate is provided with a recess corresponding to the arrangement of the LED light sources.

  Moreover, the illumination device of the present invention is provided so as to face the LED light sources and the plurality of LED light sources arranged on the circuit board, and the light from the LED light sources is incident from the light incident surface and irradiated from the light exit surface. It has a first light guide plate and a second light guide plate that receives light from the light exit surface of the first light guide plate and irradiates it from the irradiation surface. The first light guide plate corresponds to the arrangement of LED light sources. Thus, a through hole was formed, and the second light guide plate was provided with a recess corresponding to the through hole.

  Furthermore, the wall surface of the through hole and the wall surface of the recess were continuously formed. Conversely, the wall surface of the through hole and the wall surface of the recess may be formed so as to be discontinuous. The recess can be formed in a substantially conical shape.

  In addition, the display device of the present invention includes a lighting device having a plurality of LED light sources arranged on a circuit board, a light guide plate that receives light from the LED light source from the incident surface and guides the light to the output surface as illumination light, and a light guide. It has a non-self-luminous display element provided on the exit surface side of the light plate, the light guide plate is composed of an upper light guide plate and a lower light guide plate, and the lower light guide plate transmits the emitted light from each LED light source inside the light guide plate And the LED light source is arranged in the vicinity of the opening surface of the recess.

  In addition, the display device of the present invention is provided so as to face the LED light sources and the plurality of LED light sources arranged on the circuit board, and the light from the LED light sources is incident from the light incident surface and irradiated from the light output surface. The first light guide plate and the second light guide plate formed of a material having a refractive index different from that of the first light guide plate while irradiating light from the light exit surface of the first light guide plate and irradiating from the irradiation surface And a non-self-luminous display element provided on the irradiation surface side of the second light guide plate.

  In addition, the display device of the present invention is provided so as to face the LED light sources and the plurality of LED light sources arranged on the circuit board, and the light from the LED light sources is incident from the light incident surface and irradiated from the light output surface. A first light guide plate, a second light guide plate that receives light from the light exit surface of the first light guide plate and irradiates from the irradiation surface, and a non-self-light-emitting provided on the irradiation surface side of the second light guide plate The first light guide plate is provided with through holes corresponding to the arrangement of the LED light sources, and the second light guide plate is provided with recesses corresponding to the through holes.

  According to the illumination device of the present invention, an illumination device with a good luminance distribution can be realized with a small number of LED light sources. Therefore, it is also effective for power saving of the lighting device. In addition, since the light guide plates are divided and combined, a light guide plate having a complicated shape that is difficult in normal molding can be formed, and the light guide plate can be used as a part of the lighting device.

  The illumination device of the present invention will be described with reference to FIG. Fig.1 (a) is a top view which shows typically the illuminating device of this invention, FIG.1 (b) has shown typically the cross-sectional structure in the straight line PQ in Fig.1 (a). As shown in the drawing, a plurality of LED light sources 5 are arranged on the circuit board 6, a lower light guide plate 4 is provided to face the LED light sources 5, and an upper light guide plate 3 is provided above the lower light guide plate 4. Yes. Each light guide plate has a function of guiding light incident on the incident surface as illumination light to the opposite irradiation surface. A concave portion 1 for guiding the emission from each LED light source to the inside of the light guide plate is formed on the incident surface of the lower light guide plate 4, and the LED light source 5 is disposed in the vicinity of the opening surface of the concave portion 1. That is, the LED light source 5 is provided on the circuit board so that the light emitting surface faces the lower light guide plate 4. The lower light guide plate 4 has a recess 1 formed immediately above the position where the light source 5 is provided. At this time, the light emitted from the LED light source 5 is configured to irradiate the recess 1. As a result, of the light emitted from the LED light source 5, the light irradiated on the recess 1 is refracted and guided to the inside of the lower light guide plate 4. The light beam guided to the lower light guide plate 4 is guided while repeating total reflection inside the light guide plate. Further, light enters the upper light guide plate 3 from the lower light guide plate 4, further undergoes total reflection inside the upper light guide plate 3, and finally is emitted to the upper surface of the light guide plate. The surface light thus obtained becomes light having a uniform luminance distribution. Here, materials having different refractive indexes can be used for the upper light guide plate 3 and the lower light guide plate 4. As a result, when light enters the upper light guide plate 3 from the lower light guide plate 4, it is converted into a light beam diffused due to a difference in refractive index, and a more uniform luminance distribution can be obtained.

  Further, when a fine prism structure is formed on the light exit surface of the lower light guide plate 4 and the light entrance surface and the light exit surface of the upper light guide plate 3, the light extraction is efficiently performed, and the brightness is improved and the diffusion effect by the fine prism is achieved. Thus, an effect of obtaining a uniform luminance distribution can be obtained. The fine prism is formed in parallel with each side of the light guide plate or at a certain angle. If the intersection of these fine prisms is configured to substantially coincide with the center of the recess, the uniformity of the luminance distribution is improved. The pitch of the fine prisms may be constant, or may be configured so that it is dense above the recess and becomes sparse as the distance from the recess increases. According to the latter configuration, the light extraction efficiency can be adjusted.

  In addition, the size of the concave portion is generally formed in the lower light guide plate, but the size of the concave portion is set to reach the upper light guide plate, and the difference between the upper and lower refractive indexes is utilized. It is also possible to have an effect of diffusing the light beam direction in different directions at the upper and lower portions of the recess. The shape of the recess is generally spherical as a compact shape for housing the LED inside the light guide plate, but in order to obtain a greater refractive effect, the conical shape and the cross-sectional shape of the side surface of the recess are the inside of the recess. If the circular arc shape is projected, the refraction effect can be enhanced.

  By using this recess, the range that can be irradiated by individual LEDs can be widened, and a surface light source can be configured with a small number of LEDs.

  The display device of the present invention includes the illumination device having any one of the above-described configurations and a non-self-luminous display element provided on the irradiation surface side of the illumination device.

  The illumination device of the present embodiment will be described with reference to the drawings. The general outline is the same as in FIG. FIG. 2 shows a partially enlarged cross section of the illumination device of this embodiment. As shown in the drawing, the LED light source 5 is provided on the circuit board 6 so that the light emitting surface faces the light guide plate 2 side. Although not shown, wiring for supplying power to each light source is formed on the circuit board 6, and a connector for connecting these wirings to an external control circuit and a power source is also provided. Specifically, the LED light source 5 is formed of an LED element 7 and a translucent covering portion 8 that covers the LED element 7. The LED element 7 is connected to the wiring formed on the circuit board 6 by wire bonding or conductive paste. At this time, the light emitting surface of the LED element 7 faces the lower light guide plate 4 side. The upper light guide plate 3 is disposed above the lower light guide plate 4. Each light guide plate may be made of a transparent resin having the same refractive index, or may be made of a transparent resin having a different refractive index. The lower light guide plate 4 has a recess 1 formed immediately above the position where the light source 5 is provided. That is, the light emitting surface of the LED element 7 is configured to be in the vicinity of the opening surface of the recess 1. As a result, most of the light emitted from the LED element 7 is irradiated to the concave portion 1 to be transmitted / refracted and guided into the lower light guide plate 4. Further, light enters the upper light guide plate 3 from the lower light guide plate 4 and repeats total reflection inside the upper light guide plate 3. Here, when materials having different refractive indexes are used for the respective light guide plates, the light rays entering the upper light guide plate 3 are converted into more diffused light rays. The light guided to the inside of the light guide plate 2 in this manner is guided while repeating total reflection inside the light guide plate 2 except for the light irradiated to the region directly above the LED light source 5. At this time, it is desirable that the light emitting surface of the LED element 7 is on the same plane as the opening surface of the recess 1 provided in the lower light guide plate 4, that is, at the same claw position.

  In the present embodiment, the concave portion 1 has a hemispherical shape in the lower light guide plate 4, and the cross-sectional shape thereof is a semicircle. This hemispherical shape should be formed in a size that can accommodate the light source 5 and should be made smaller. When the thickness of the lower light guide plate is 5 mm, the diameter is suitably 4 mm.

  Moreover, the light source 5 is arrange | positioned at the grid | lattice form, and the recessed part 1 is formed similarly. Further, a fine prism structure is formed on the upper surface of the lower light guide plate 4 and the upper and lower surfaces of the upper light guide plate 3. The arrangement pattern of the fine prisms will be described with reference to FIGS. The fine prism 10 is usually formed such that its ridge line is parallel to each line connecting the concave portions 1 (or LED light sources 5) arranged in a lattice shape as shown in FIGS. Alternatively, as shown in FIG. 5, it can be formed so as to be parallel to the rectangular diagonal line formed by the recess 1. These fine prism structures are formed by connecting a crossing point at a point above the concave portion 1 (or LED light source 5) and a line connecting from one concave portion to the adjacent concave portion as one region, and the fine prism 10 existing in the region. It is possible to apply a constant or variable pitch to each region. Normally, the fine prisms 10 in the region are formed at equal pitches such that p1 = p2 as shown in FIG. 2, but the upper part of the recess 1 is densely arranged so that p3 <p4 as shown in FIG. It can also be formed sparsely as it moves away from it. Normally, the upper light guide plate 3 and the lower light guide plate 4 have the same prism structure, but the prism structures can be formed with different sizes, pitches, and arrangements. In this embodiment, the cross-sectional shape of the fine prism 10 is an isosceles triangle, and its apex angle is about 90 degrees. Moreover, the height should just be 10-100 micrometers and the length of a hypotenuse should be 20-200 micrometers. Furthermore, when the fine prisms 10 are formed sparsely as they move away from above the LED, the pitch between the dense parts is 30 to 100 μm, and the sparse part is 300 to 600 μm. When this pitch is considered as a function of the distance from the central portion, it is a quadratic function. By optimizing the rate of change of the pitch in accordance with the thickness of the light guide plate 2 and the arrangement between the recesses, it becomes possible to adjust the amount of light emitted from the light exit surface of the light guide plate 2. As a result, illumination with uniform brightness can be realized.

  Further, as shown in FIG. 2, a light reflection layer 9 is disposed between the lower light guide plate 4 and the circuit board 6 except for a portion where the LED light source 5 exists. The light reflection layer 9 has an effect of improving light utilization efficiency by reflecting and reusing light leaked from the lower light guide plate 4 to the circuit board 6 side. As the light reflecting layer 9, a layer formed by vapor-depositing silver, a silver compound or aluminum on a polymer film, or a resin binder mixed with a white pigment was applied to form a reflecting layer. Things can be used. Of course, the light reflecting layer 9 may be directly formed on the surface of the circuit board 6 through an electrically insulating layer.

  The direct type illumination device of this example was able to realize substantially the same luminance and good luminance distribution even when the number of LED light sources used was 30 to 50% less than that of a sidelight illumination device of the same size.

  Next, the illuminating device of a present Example is demonstrated based on figures. FIG. 8 is a cross-sectional view schematically showing an enlarged vicinity of the concave portion of the lighting device. In the first embodiment, the case where the concave portion 12 is formed in a hemispherical shape as shown in FIG. 7 is described. However, in this embodiment, the concave portion 13 provided in the lower light guide plate 4 as shown in FIG. Describe the case. Since other than that is the same as that of Example 1, the detail is abbreviate | omitted. The cone is a cone whose cross-sectional shape is formed so as to protrude inside the recess 13 and is isosceles triangle. By making the side surface of the concave portion into a cone, light incident on the lower light guide plate 4 is greatly refracted, and light can be diffused into the lower light guide plate 4. Furthermore, since the light emitted almost directly from the light source 5 enters the light exit surface of the light guide plate 2 at a large angle near the critical angle after entering from the side wall of the recess 13, Light can be efficiently guided inside the light guide plate. As a cone shape having a high diffusion effect, it is desirable that the base angle of the isosceles triangle is about 60 to 85 degrees. If the total thickness of the light guide plate 2 is 10 mm, it is suitable that the depth of the recess 13 is 4 to 5 mm. Furthermore, as shown in FIG. 2, the fine prism structure formed on the light emitting surface of the light guide plate 2 effectively acts to realize a lighting device having uniform and bright radiance.

  In FIG. 9, the concave portion 13 is larger than the thickness of the lower light guide plate 4 and has a cone that reaches the upper light guide plate 3. Since the height of the cone can be increased, the base angle can be increased, and the refraction effect at the concave section can be enhanced. Further, not only the lower light guide plate 4 but also the upper light guide plate 3 can be directly irradiated with light, and the light can be diffused inside the light guide plate 2. As a desirable shape of the cone at this time, if the base angle of the isosceles triangle is about 60 to 85 degrees and the total thickness of the light guide plate 2 is 10 mm, the total depth of the recess 13 is 7 to 8 mm. Is suitable. In addition, when materials having different refractive indexes are used for the upper light guide plate 3 and the lower light guide plate 4, the recesses 13 on the upper light guide plate 3 side and the recesses 13 on the lower light guide plate 4 side are used for the materials constituting each light guide plate. Different light diffusion effects can be obtained due to the difference in refractive index. In general, the upper light guide plate 3 needs to diffuse light from the light source more than the lower light guide plate 4, so that a higher diffusion effect can be obtained if the refractive index of the upper light guide plate 3 is larger than the refractive index of the lower light guide plate 4. And a uniform luminance distribution can be obtained.

  10 and 11 show a case where the shape of the recess 1 on the upper light guide plate 3 side is different from the conical shape formed by the recess of each light guide plate. If the concave portion on the upper light guide plate 3 side is the upper concave portion 13a and the concave portion on the lower light guide plate 4 side is the lower concave portion 13b, the upper light guide plate 3 side and the lower light guide plate are changed from the light source 5 by changing the shape of the upper concave portion 13a. An effect of adjusting the spread of the incident angle with respect to the light incident on the concave portion on the four side can be provided. Further, when a fine prism is formed on the upper light guide plate 3 and the lower light guide plate 4, a gap is generated between them, and therefore a gap as shown in FIG. 10 is also formed in the concave portion, so that a complete conical shape is not obtained. Therefore, the light incident from the light source 5 escapes from the gap, and ring-shaped light is seen on the upper surface of the upper light guide plate 3, affecting the uniformity. As the shape of each concave portion to prevent this, the base angle of the cone formed with the upper concave portion 13a is made smaller than the base angle of the cone formed with the lower concave portion 13b. Can be mentioned. Alternatively, when the base angle of the cone formed with the upper concave portion 13a is the same as the base angle of the cone formed with the lower concave portion 13b, the base of the former cone is replaced with the latter cone. It is mentioned to make it larger than the bottom of By enlarging the upper concave portion 13b in this way, it is possible to irradiate all the incident light from the light source 5 onto the side surface of the concave portion, and a large luminance distribution is improved.

  Next, the illuminating device of a present Example is demonstrated based on figures. 12 and 13 are cross-sectional views schematically showing the lighting device partially enlarged. In this embodiment, the recess 14 provided in the light guide plate 2 has an arc shape. Since other than that is the same as that of Example 1, the detail is abbreviate | omitted. In FIG. 12, an arc-shaped recess 14 is formed in the lower light guide plate, and the arc shape is formed so as to protrude inside the recess 14. By making the side surface of the recess 14 into an arc shape, the light emitted almost directly from the light source 5 reaches the light emitting surface of the light guide plate 2 at a larger angle than in the case of a cone. Light from the light source 5 can be efficiently guided into the lower light guide plate 3. Thus, by making the recessed part 14 into circular arc shape, a more uniform illuminating device is realizable rather than the case of a cone shape.

  In FIG. 13, as described in the second embodiment, the concave portion is larger than the thickness of the lower light guide plate 4 and has an arc shape reaching the upper light guide plate 3. Details are described in the second embodiment, and are omitted here. As described in the second embodiment, even in the case of an arc shape, it is possible to obtain a wide range of different incident angles due to the difference in the refractive index of the material of the upper light guide plate 3 and the lower light guide plate 4 as in the case of a cone. As a result, a uniform effect on the luminance distribution can be obtained.

  Further, in the case of an arc shape, as shown in FIGS. 10 and 11, the case where the shapes of the upper concave portion 13a and the lower concave portion 13b are not shown is not shown, but the present invention can be sufficiently applied to the arc shape.

  Next, the proving apparatus of the present embodiment will be described with reference to the drawings. 14 and 15 are cross-sectional views schematically showing the illuminating device partially enlarged. In FIG. 14, the upper light guide plate 3 and the lower light guide plate 4 are joined using the diffusion adhesive layer 11 without forming a fine prism on the contact surface between the upper light guide plate 3 and the lower light guide plate 4. The diffusion adhesive layer 11 is a combination of a diffusion effect and an adhesive effect, and examples thereof include a diffusion adhesive film. By using this diffusion adhesive layer 11, the upper light guide plate 3 and the lower light guide plate 4 can be handled as an integrated light guide plate, and a uniform illumination device can be realized by a diffusion effect. In addition, the diffusion adhesive layer 11 can be used even when the fine prism 10 is present as shown in FIG. 15, and the illumination device has a better luminance distribution due to the diffusion effect of the fine prism 10 and the diffusion adhesive layer 11. Can be obtained.

  In each embodiment described above, a transparent material is used for the light guide plate 2. As the transparent material to be used, an acrylic resin (refractive index = about 1.5), a polycarbonate resin (refractive index = about 1.6), or a cycloolefin resin (refractive index = about 1.5) is suitable. In order to clarify the difference in refractive index between the upper light guide plate and the lower light guide plate, a transparent material that can be set in the range of refractive index = 1.4 to 1.7 can be used.

  FIG. 16 is a perspective view schematically showing the configuration of the liquid crystal display device of this embodiment. As shown in the figure, this liquid crystal display device is configured to illuminate a liquid crystal element using the illumination device having the configuration described in each of the above-described embodiments. A diffusion sheet 16 and a prism sheet 17 are disposed between the illumination device 15 and the liquid crystal element 18. A connector cable 20 for supplying power to the LED light source on the circuit board is disposed on the circuit board of the illumination device 15. The liquid crystal element 18 is provided with a connector cable 19 for supplying an image signal and power thereto.

  The light emitted from the illumination device 15 is diffused by the diffusion sheet 16 to become more uniform light, and enters the prism sheet 17. The prism sheet 17 is a transparent sheet in which a prism group having parallel ridgelines with a substantially right apex angle is formed, and has a function of aligning light components in a direction perpendicular to the ridgelines more vertically. In FIG. 16, only one prism sheet 17 is provided, but two prism sheets having ridge lines orthogonal to each other may be arranged. In addition, the prism sheet 17 can be omitted when the emitted light is emitted vertically to the illumination device. Moreover, it is also possible to use it in a configuration in which the diffusion sheet 16 is omitted. Furthermore, when a light reflection layer is formed on the back surface of the illumination device 15, it is possible to improve the light utilization efficiency by arranging a selective reflection polarizer in the gap between the illumination device 15 and the liquid crystal element 18. As the liquid crystal element 18, either a simple matrix type liquid crystal element or an active matrix type liquid crystal element can be used.

  In each of the above-described embodiments, the circuit board 6 may be a glass epoxy board or a polyimide film board that is usually used. Since these circuit boards 6 can easily carry out multilayer wiring, they are suitable for mounting a large number of LED light sources thereon.

  The liquid crystal display device having the above-described configuration can display a uniform bright image with fewer LED light sources.

It is a schematic diagram which shows the structure of the illuminating device by this invention. It is the elements on larger scale explaining the structure of the illuminating device by this invention. It is a schematic diagram which shows typically the Example of a fine prism. It is a schematic diagram which shows typically the Example of a fine prism. It is a schematic diagram which shows typically the Example of a fine prism. It is the elements on larger scale which show the structure of the Example of this invention. It is a fragmentary sectional view explaining the example of composition of a crevice typically. It is a fragmentary sectional view explaining the example of composition of a crevice typically. It is a fragmentary sectional view explaining the example of composition of a crevice typically. It is a fragmentary sectional view explaining the example of composition of a crevice typically. It is a fragmentary sectional view explaining the example of composition of a crevice typically. It is a fragmentary sectional view explaining the example of composition of a crevice typically. It is a fragmentary sectional view explaining the example of composition of a crevice typically. It is a fragmentary sectional view which shows typically the structure of the illuminating device by this invention. It is a fragmentary sectional view which shows typically the structure of the illuminating device by this invention. It is a perspective view which shows typically the structure of the liquid crystal display device by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Recessed part 2 Light guide plate 3 Upper light guide plate 4 Lower light guide plate 5 Light source 6 Circuit board 7 LED element 8 Translucent covering part 9 Light reflection layer 10 Fine prism structure 11 Diffusion adhesive layer 12 Recessed part (hemispherical shape)
13 Concave (substantially conical)
13a Upper recessed part 13b Lower recessed part 14 Recessed part (arc shape)
DESCRIPTION OF SYMBOLS 15 Illumination device 16 Diffusion sheet 17 Prism sheet 18 Liquid crystal element 19, 20 Connector cable

Claims (23)

  An illumination apparatus comprising: a plurality of LED light sources arranged on a circuit board; and a light guide plate that receives light from the LED light source from an incident surface and guides the light as an illumination light to an output surface. The light guide plate includes an upper light guide plate and a lower light guide plate The light guide plate includes a concave portion for guiding light emitted from each LED light source into the light guide plate, and the LED light source is disposed in the vicinity of the opening of the concave portion. Lighting device.   2. The LED light source and the concave portion are arranged in a lattice shape, the concave portion is formed above the LED light source, and the LED light source forms a square or a rectangle by three other LED light sources in the vicinity. The lighting device described in 1.   3. The illumination device according to claim 1, wherein a fine prism structure is formed on a light incident surface and an output surface of the upper light guide plate and a light output surface of the lower light guide plate.   The illumination device according to claim 2, wherein the fine prism structure is arranged in parallel to each side of a square or a rectangle formed by the LED light source, and is also arranged in parallel to a diagonal line thereof.   The illumination device according to claim 3 or 4, wherein a pitch of the fine prism structure is constant.   5. The illumination device according to claim 3, wherein a pitch of the fine prism structure is not constant but becomes dense just above the recess and becomes sparse as the distance from the recess increases.   The illumination device according to claim 1, wherein the concave portion has a substantially hemispherical shape.   The illumination device according to claim 1, wherein the concave portion is a substantially conical body.   The lighting device according to any one of claims 1 to 6, wherein a cross-sectional shape of the concave portion is a part of an arc protruding outside the concave portion.   The lighting device according to claim 1, wherein the upper light guide plate and the lower light guide plate are formed of materials having different refractive indexes.   The lighting device according to any one of claims 1 to 10, wherein the upper light guide plate and the lower light guide plate are joined by a diffusion adhesive layer.   The illumination device according to any one of claims 1 to 11, wherein a light incident surface of the lower light guide plate is covered with a light reflecting material except for a region near the concave portion. A plurality of LED light sources disposed on a circuit board;
A first light guide plate that is provided so as to face the LED light source and that irradiates light from the LED light source from a light incident surface and irradiates from a light exit surface;
A second light guide plate that receives light from the light exit surface of the first light guide plate and irradiates from the irradiation surface; and
The lighting device, wherein the first light guide plate and the second light guide plate are formed of materials having different refractive indexes.   The illumination device according to claim 13, wherein a concave portion is provided on the light incident surface of the first light guide plate in correspondence with the arrangement of the LED light sources. A plurality of LED light sources disposed on a circuit board;
A first light guide plate that is provided so as to face the LED light source and that irradiates light from the LED light source from a light incident surface and irradiates from a light exit surface;
A second light guide plate that receives light from the light exit surface of the first light guide plate and irradiates from the irradiation surface; and
The first light guide plate is provided with a through hole corresponding to the arrangement of the LED light sources,
The lighting device, wherein the second light guide plate is provided with a recess corresponding to the through hole.   The lighting device according to claim 15, wherein a wall surface of the through hole is formed continuously with a wall surface of the recess.   The lighting device according to claim 15, wherein a wall surface of the through hole is formed discontinuously with a wall surface of the recess.   The lighting device according to claim 16, wherein the concave portion is a substantially conical body.   The concave portion is a substantially conical body, and a base angle of the substantially conical body is larger than a base angle formed by a through hole of the lower light guide plate and a light incident surface of the lower light guide plate. The lighting device described.     The lighting device according to claim 17, wherein the concave portion is a substantially conical body, and a bottom side of the substantially conical body is larger than a bottom side formed by the through hole on a light output surface of the lower light guide plate. Provided on the exit surface side of the light guide plate, and a lighting device having a plurality of LED light sources arranged on the circuit board, a light guide plate that enters the light from the LED light source from the incident surface and guides it to the exit surface as illumination light A display device comprising a non-self-luminous display element,
The light guide plate is composed of an upper light guide plate and a lower light guide plate, and the lower light guide plate has a recess for guiding light emitted from each LED light source to the inside of the light guide plate, and the LED light source is in the vicinity of the opening surface of the recess. A display device characterized by being arranged in A plurality of LED light sources disposed on a circuit board;
A first light guide plate that is provided so as to face the LED light source and that irradiates light from the LED light source from a light incident surface and irradiates from a light exit surface;
The light from the light exit surface of the first light guide plate is incident and irradiated from the irradiation surface, and the second light guide plate formed of a material having a refractive index different from that of the first light guide plate;
And a non-self-luminous display element provided on the irradiation surface side of the second light guide plate. A plurality of LED light sources disposed on a circuit board;
A first light guide plate that is provided so as to face the LED light source and that irradiates light from the LED light source from a light incident surface and irradiates from a light exit surface;
A second light guide plate that receives light from a light exit surface of the first light guide plate and irradiates from an irradiation surface; and
While comprising a non-self-luminous display element provided on the irradiation surface side of the second light guide plate,
The first light guide plate is provided with a through hole corresponding to the arrangement of the LED light sources,
The display device, wherein the second light guide plate is provided with a recess corresponding to the through hole.

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