JP5489020B2 - Surface light source and liquid crystal display device - Google Patents

Description

  The present invention relates to a surface light source and a liquid crystal display device including the surface light source.

  Liquid crystal display devices are used in a wide range of fields such as OA devices, AV devices, and portable terminal devices because of their thinness, light weight, and low power consumption. This liquid crystal display device is composed of a liquid crystal panel in which liquid crystal is sandwiched between two opposing substrates, a surface light source (backlight) for illuminating the liquid crystal panel, a housing for holding these, and the like. In order to improve the performance of the device, various proposals have been made regarding the backlight.

  For example, Patent Document 1 below discloses a method for improving tail blurring (moving image blur) when displaying a moving image in a liquid crystal display device including an edge light type backlight in which a light source is disposed on a side surface of a light guide plate. Is disclosed. FIG. 13 shows the configuration of the backlight 11 of the liquid crystal display device. The backlight 11 includes a white LED 1101, an LED array 1102, a light guide plate 1104, and a reflection plate 1105.

  The light guide plate 1104 is divided into a plurality of strip-shaped rectangular parallelepiped blocks, and one or more white LEDs 1101 are arranged on the end face (side surface) in the longitudinal direction of each block. A reflective plate 1105 is disposed between the adjacent light guide plates 1104. And the light radiate | emitted from white LED1101 injects from the end surface close | similar to white LED1101 of the light-guide plate 1104, and is propagated, repeating total reflection. At this time, the light leaking from the light guide plate 1104 is reflected by the reflection plate 1105, so that the light guide plates 1104 that are substantially adjacent to each other are optically separated.

JP 2001-092370 A

  However, the backlight having the above structure has the following problems.

  The first problem is that it is difficult to increase the brightness of the backlight. The reason is that the white LED 1101 is arranged on the end face in the longitudinal direction of each light guide plate 1104 divided into blocks, but the area of the end face of the light guide plate 1104 is smaller than the area of the illumination region of the backlight 11. This is because the number of white LEDs 1101 cannot be increased in order to increase the luminance.

  The second problem is that it is difficult to increase the size of the backlight. The reason for this is that when the illumination area of the backlight 11 is enlarged, the number of white LEDs 1101 needs to be increased in proportion to the area of the illumination area, but as described above, the area of the end face of the light guide plate 1104 is: This is because the number of white LEDs 1101 cannot be increased because the area of the illumination region of the backlight 11 is much smaller, and the luminance of the backlight 11 is reduced.

  A third problem is that uneven brightness occurs in the backlight. The reason is that when the reflector 1105 is disposed between the adjacent light guide plates 1104, a gap is generated between the light guide plates 1104, and that portion emits light slightly due to the non-light emitting portion (or the leaked light from the adjacent light guide plate 1104). It is because it is recognized as a part to be performed.

  The present invention has been made in view of the above problems, and a main object thereof is a surface light source capable of achieving high brightness and large size while suppressing luminance unevenness, and a liquid crystal display including the surface light source. To provide an apparatus.

To achieve the above object, according to the present invention, in a surface light source for illuminating a liquid crystal panel, a light guide plate disposed on a back surface of the liquid crystal panel and a plurality of light guide plates disposed on a surface opposite to the liquid crystal panel. The light guide plate guides the light from the plurality of light sources and holds optical sheets, and the longitudinal direction of the liquid crystal panel is the liquid crystal when viewed from the normal direction. The plurality of blocks are divided into a plurality of blocks parallel to one side of the panel, and the plurality of blocks are arranged at intervals from each other , and a reflective layer is formed on at least the surface of the hollow portion side of the adjacent blocks, The light sources are arranged in the longitudinal direction of each block of the light guide plate and the hollow portion between the blocks.

  The surface light source and the liquid crystal display device of the present invention have the following effects.

  The first effect of the present invention is that the luminance of the surface light source can be increased. The reason is that the light source such as LED is not arranged on the side surface of the light guide plate but on the back side opposite to the liquid crystal panel, so that the light source can be spread over the entire illumination area, and the light guide plate or liquid crystal This is because the number of light sources per unit area of the panel can be increased.

  The second effect of the present invention is that the surface light source can be increased in size. The reason is that as the area of the illumination region increases, the number of light sources that can be arranged can be increased accordingly, and thus the area of the illumination region can be expanded without reducing the luminance.

  A third effect of the present invention is that luminance unevenness of the surface light source can be suppressed. The reason is that the light source is arranged on the back side of the light guide plate so that the light source and the liquid crystal panel face each other, and a thick reflector for suppressing light leakage is introduced as in the case where the light source is arranged on the side surface of the light guide plate. This is because it is not necessary to intervene between the light plates, so that the non-light emitting portion can be reduced and the luminance uniformity can be enhanced.

1 is a perspective view schematically showing a configuration of a liquid crystal display device according to a first embodiment of the present invention. It is a perspective view which shows typically the structure of the liquid crystal display device which concerns on the 2nd Example of this invention. It is a perspective view which shows typically the structure of the liquid crystal display device which concerns on the 3rd Example of this invention. It is a perspective view which shows typically the structure of the liquid crystal display device which concerns on the 4th Example of this invention. It is the top view and side view which show typically the structure of the light-guide plate which concerns on the 5th Example of this invention. It is a sectional side view which shows typically the other structure of the light-guide plate which concerns on the 5th Example of this invention. It is a figure which shows the optical path in the light guide plate of the light emitted from LED. It is a sectional side view which shows typically the structure of the liquid crystal display device which concerns on the 6th Example of this invention. It is a sectional side view which shows typically the other structure of the liquid crystal display device based on the 6th Example of this invention. It is a sectional side view which shows typically the other structure of the liquid crystal display device based on the 6th Example of this invention. It is a figure which shows the relationship between the writing timing of the image data in the liquid crystal display device which concerns on the 6th Example of this invention, and the lighting timing of a light source. It is a figure which shows the relationship between the writing timing of the image data in the liquid crystal display device which concerns on the 6th Example of this invention, and the lighting timing of a light source. It is a figure which shows the structure of the backlight in the conventional liquid crystal display device.

  As shown in the background art, a backlight having a structure in which a light guide plate is divided into strip-shaped rectangular parallelepiped blocks and a light source is arranged on an end face in the longitudinal direction of each block is known. However, in this structure, since the number of light sources that can be arranged on the end face of the light guide plate is limited, it is difficult to achieve high brightness and large size. In addition, the direction of the light incident on the light guide plate and the direction of the light emitted from the light guide plate are greatly different and light is likely to leak, so a thick reflector must be placed between each block, and a reflector is placed Such a portion becomes a non-light emitting portion, resulting in uneven brightness.

  Therefore, in the present invention, the light source is not arranged on the end face in the longitudinal direction of each block of the rectangular parallelepiped, but the light source is arranged on the back surface opposite to the liquid crystal panel. Thereby, since the area | region which arrange | positions a light source can be enlarged, high brightness and enlargement can be achieved easily. Moreover, since the light source and the liquid crystal panel are opposed to each other by disposing the light source on the back surface of the light guide plate, it is difficult for light to leak. Therefore, the non-light emitting portion caused by the reflection plate for separating the light guide plate is reduced to reduce luminance unevenness. Can be suppressed.

  In order to describe the above-described embodiment of the present invention in more detail, a surface light source and a liquid crystal display device according to a first example of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view schematically showing the configuration of the liquid crystal display device of the present embodiment, and FIG. 7 is a view showing an optical path in a light guide plate of light emitted from an LED.

  As shown in FIG. 1, the liquid crystal display device 1 of this embodiment includes a light source 103, a light guide plate 104, sheets 105, a liquid crystal panel 106, and the like, each of which has an LED 101 mounted on an LED mounting substrate 102 as a light source. Composed.

  The LED 101 is, for example, a combination of chips emitting white or RGB monochromatic light combined in a single package, or a combination of light emitting diodes emitting monochromatic light at an arbitrary ratio.

  The LED mounting board 102 includes a structure for fixing the LED 101 and a wiring pattern for connecting the electrodes of the LED 101, and supplies power supplied from an external power supply circuit (not shown) to each LED 101. The shape of the LED mounting substrate 102 is not particularly limited, and may be a strip shape corresponding to the shape of each light guide plate 104 or a flat plate shape corresponding to the shape of the entire light guide plate 104. A light source 103 is configured by mounting a plurality of LEDs 101 in an array shape, a staggered lattice shape, or the like on a strip-like or flat-plate-like LED mounting substrate 102.

  The light guide plate 104 is composed of a plurality of rectangular parallelepipeds (referred to as blocks) divided into strips, and the plurality of blocks are arranged in parallel. The longitudinal dimension of each block of the light guide plate 104 is substantially the same as the long side of the liquid crystal panel 106, and each surface of each block of the light guide plate 104 is smooth. Adjacent blocks are fixed so that the interval (gap) is approximately 0.5 mm or less. The fixing structure is not particularly limited. For example, a structure in which the fixing structure is sandwiched and fixed from the outside of the blocks arranged at both ends is preferable.

  In FIG. 1, each block of the light guide plate 104 is divided so that the longitudinal direction thereof is parallel to the long side of the liquid crystal panel 106, but may be divided so as to be parallel to the short side of the liquid crystal panel 106. Alternatively, the liquid crystal panel 106 may be divided in a direction intersecting the long side and the short side. In FIG. 1, the light guide plate 104 is divided into five blocks, but the width of each block may be an integer multiple of the pixels of the liquid crystal panel 106, and the number of divisions is arbitrary.

  Further, it is desirable to increase the reflectance by making the surface of the light guide plate 104 a mirror surface or the like. For example, a reflective sheet made of a silver vapor deposited film or the like is disposed on the entire surface or one surface of the light guide plate 104 excluding the region facing the liquid crystal panel 106 and the area facing the LED 101, or by vapor deposition, sputtering, plating, coating, or the like. It is desirable to form a thin reflective layer.

  The sheets 105 are constituted by a diffusion sheet, a lens sheet, a polarizing sheet, and the like, and make the light emitted from the light guide plate 104 be uniform light and enter the liquid crystal panel 106. The sheets 105 can be omitted as necessary.

  The liquid crystal panel 106 includes liquid crystal sandwiched between one substrate on which a switching element such as a thin film transistor (TFT) is formed, the other substrate on which a color filter, a black matrix, or the like is formed, and both substrates. It is composed of materials.

  A liquid crystal panel 106 is arranged on the front side of the light guide plate 104 composed of a plurality of blocks via sheets 105, a light source 103 is arranged on the back side of the light guide plate 104, and a power circuit (not shown) is provided on the light source 103. The drive circuit (not shown) is connected to the liquid crystal panel 106, and the liquid crystal display device 1 of the present embodiment is completed by holding and fixing them with a housing (not shown).

  In addition, a present Example has the characteristics in the structure of the light-guide plate 104, and arrangement | positioning of LED101, The structure, arrangement | positioning, material, etc. of another member are not specifically limited. For example, the configuration and arrangement of the power supply circuit that turns on the LED 101, the connection method, the configuration of the sheets 105, the structure and type of the liquid crystal panel 106, the configuration and arrangement of the drive circuit that drives the liquid crystal panel 106, the connection method, and each member The structure, shape, and the like of the housing that holds and fixes the housing are arbitrary.

  Next, the operation of the liquid crystal display device 1 having the above configuration will be described.

  The LED 101 is driven by direct current or PWM (Pulse Width Modulation), and the light emitted from the LED 101 is incident on the opposing light guide plates 104 and travels straight in the light guide plate 104 as shown in FIG. Or it advances, repeating total reflection on the side, and is emitted from the end face on the liquid crystal panel 106 side. Further, as shown in FIG. 7B, a part of the light is reflected by the end face of the light guide plate 104 on the liquid crystal panel 106 side, but again by the reflective layer formed on the end face facing the LED 101, the liquid crystal panel 106. Reflected to the side.

  The plurality of lights incident on the light guide plate 104 from the LED 101 are mixed while propagating through the light guide plate 104, and are sufficiently mixed when emitted from the liquid crystal panel 106 side end surface of the light guide plate 104.

  Thus, in this embodiment, since the LEDs 101 are arranged on the back surface of the light guide plate 104, the LEDs 101 can be arranged more densely than in the structure in which the light sources are arranged on the side surfaces of the light guide plate, thereby increasing the brightness. Can be easily achieved. Further, when the liquid crystal panel 106 is enlarged, the area of the back surface of the light guide plate 104 is increased, and the number of the LEDs 101 to be mounted is increased, so that an increase in size can be easily achieved.

  Further, in this embodiment, since the LED 101 is disposed on the back surface of the light guide plate 104, the light emitted from the side surface of the light guide plate 104 is substantially determined by the refractive index of the light guide plate 104 and the lens design, structure design, and arrangement of the LED 101. The light leaking from between the adjacent light guide plates 104 can be reduced. Therefore, it is not necessary to partition each light guide plate 104 with a thick reflector, and the interval between each light guide plate is almost “0” (even if a reflective sheet is disposed on the surface of the light guide plate, even if a reflective sheet is arranged) 200 μm or less), the area that becomes the non-light-emitting portion can be reduced, and thereby uneven luminance can be suppressed.

  Also, by dividing each light guide plate 104 into blocks of rectangular parallelepiped, it is possible to limit the area of the backlight illuminating surface irradiated with light incident from the LED 101, so it is easy to improve luminance and color unevenness in that area. . Further, by providing a sensor or the like for each block of the light guide plate 104, the luminance and chromaticity can be controlled independently. Further, the luminance and chromaticity in the light guide plate 104 can be adjusted by dividing each light guide plate 104 into a plurality of LEDs 101 and a plurality of circuits for driving the LEDs 101.

  Next, a surface light source and a liquid crystal display device according to a second embodiment of the present invention will be described with reference to FIG. FIG. 2 is a perspective view schematically showing the configuration of the liquid crystal display device of this embodiment.

  In the first embodiment described above, the blocks of the light guide plate are brought into close contact with each other. However, in this embodiment, as shown in FIG. The blocks are arranged at a predetermined interval (in this case, the width of the block), hollow portions 207 are formed between adjacent blocks, and the LEDs 201 are arranged on the back side of each block of the light guide plate 204 and each hollow portion 207. ing.

  In this case, a reflection sheet made of a silver vapor deposition film or the like is disposed on the end surface of each block of the light guide plate 204 facing the space that is the hollow portion 207, or by vapor deposition, sputtering, plating, coating, or the like. By forming the thin reflective layer 209, it is possible to prevent color mixture of light and light leakage between blocks.

  Next, a surface light source and a liquid crystal display device according to a third embodiment of the present invention will be described with reference to FIG. FIG. 3 is a perspective view schematically showing the configuration of the liquid crystal display device of this embodiment.

  When each LED is combined with a chip that emits white or RGB monochromatic light, the light guide plate can sufficiently mix the colors, but each LED is composed only of a chip that emits a single color such as R, G, B, etc. In such a case, there may be a case where the light guide plate alone cannot sufficiently mix colors. Therefore, in this embodiment, the LEDs 301 are arranged in a certain combination (GRBG, GBRBG, etc.), and as shown in FIG. 3, the light guide plate is replaced with the light guide plate 304b on the LED 301 side and the light guide plate 304a on the liquid crystal panel 306 side. Divided and a diffusion layer 308 is disposed between them.

  By combining the diffusion layer 308 with the light guide plate in this way, the color mixing property of the light emitted from the LED 301 can be improved and the light guide plate does not have to be thick for color mixing, so that the liquid crystal display device is thin. Can be achieved.

  In FIG. 3, the light guide plate is substantially equally divided, but the division position is arbitrary. In FIG. 3, the light guide plate is divided in the thickness direction, and the diffusion layer 308 is provided therebetween. However, the light guide plate is not divided, and the diffusion layer is provided on the liquid crystal panel 306 side surface or the LED 301 side surface of the light guide plate 304 a. 308 may be arranged. The diffusion layer 308 may be formed of a member that scatters and transmits light, and the thickness and material of the diffusion layer 308 and the structure for fixing the light guide plate and the diffusion layer 308 are not particularly limited. In addition, the diffusion layer 308 is desirably a strip shape corresponding to the shape of each block of the light guide plate, but may be a flat plate shape corresponding to the shape of the entire light guide plate.

  Next, a surface light source and a liquid crystal display device according to a fourth embodiment of the present invention will be described with reference to FIG. FIG. 4 is a perspective view schematically showing the configuration of the liquid crystal display device of this embodiment.

  In the first to third embodiments described above, the light guide plate is divided into strips so that the longitudinal direction of each block of the light guide plate is parallel to the long side or short side of the liquid crystal panel. Since it is not necessary to insert a thick reflecting plate between the light guide plates, the light guide plate can be divided into arbitrary shapes.

  Therefore, in this embodiment, as shown in FIG. 4, the light guide plate 404 is divided into a matrix parallel to the long and short sides of the liquid crystal panel 406, and one or more LEDs 401 are arranged on the back side of each block. To do. Thereby, the illumination surface of the backlight is divided vertically and horizontally, and finer adjustment of luminance and chromaticity can be made possible.

  In FIG. 4, the light guide plate 104 is divided into 5 × 6 30 blocks, but the width of each block may be an integer multiple of the pixels of the liquid crystal panel 106, and the number of divisions is arbitrary. Further, when viewed from the normal direction of the liquid crystal panel 106, each block may be square or rectangular.

  Next, a surface light source and a liquid crystal display device according to a fifth embodiment of the present invention are described with reference to FIGS. 5 and 6 are diagrams schematically showing the configuration of the light guide plate of the present embodiment.

  In the fourth embodiment described above, the cross-sectional shape of each light guide plate (the cross-sectional shape of the surface parallel to the liquid crystal panel surface) is rectangular, but in this embodiment, as shown in FIG. The cross-sectional shape of the optical plate is a honeycomb. At this time, the shape of each block of the light guide plate 504 is a hexagonal column shape (light guide plate 504a) as shown in FIG. Furthermore, the shape (light guide plate 504c) having a curved surface can be used.

  Moreover, the longitudinal cross-sectional shape (cross-sectional shape of a surface parallel to the normal line of a liquid crystal panel) of a light-guide plate may not be a rectangle, For example, it can be set as various shapes as shown in FIG. Specifically, in the light guide plates 604a to 604f, at least one of the end surface on the LED side or the end surface on the liquid crystal panel is a convex surface or a concave surface. The light guide plate 604g is a wedge-shaped polygon in which the width of the LED-side end face of the light guide plate is approximated to the LED light-emitting portion size, and the width is gradually increased toward the end face on the liquid crystal panel side. The light guide plates 604 h to 604 have a curved surface or a staircase shape as a modified example. The light guide plate 604j is provided with a recess capable of accommodating the LED on the end face on the LED side. The light guide plate 604k is filled with a filling material 609 made of a material constituting the light guide plate such as silicone resin or a material optically similar to the resin filled in the light emitting portion of the LED. is there. In the light guide plate 604m, a lens-shaped light collector 613 is disposed between the light guide plate and the LED 601.

  In each of the above shapes, if necessary, a reflective sheet composed of a silver vapor deposition film or the like is disposed on the entire surface or one surface excluding the region facing the liquid crystal panel of the light guide plate and the LED, or vapor deposition, sputtering, plating, A thin reflective layer may be formed by coating or the like. Thereby, the improvement of the incident efficiency of the light from LED to a light-guide plate and the weight reduction of a light-guide plate can be anticipated. In FIG. 5, the cross-sectional shape of the light guide plate is a hexagon, but it can be any polygon (for example, a triangle, a rhombus, a parallelogram, etc.) that can be combined without a gap.

  Next, a surface light source and a liquid crystal display device according to a sixth embodiment of the present invention will be described with reference to FIGS. 8 to 10 are side sectional views schematically showing the configuration of the liquid crystal display device of this example.

  In the first to third embodiments described above, a point light source such as an LED is used as the light source. However, in each embodiment, a linear light source such as a CCFL (Cold Cathode Fluorescent Lamp) may be used as the light source. it can. 8 is an example in which the line light source 812 is arranged in the configuration of FIG. 1 in the first embodiment, and FIG. 9 is an example in which the line light source 812 is arranged in the configuration of FIG. 2 in the second embodiment. FIG. 10 is an example in which a line light source 1012 is arranged in the configuration of FIG. 3 of the third embodiment.

  In this case, in order to prevent the light from the line light sources 812, 912, 1012 from entering the adjacent light guide plates 804, 904, 1004 other than immediately above, the light from the line light sources 812, 912, 1012 is efficiently guided. In order to guide to 804, 904, and 1004, reflectors 811, 911, and 1011 are arranged for each line light source. Thereby, the same effect as when LED is used as a light source can be obtained.

  8 to 10 show an example in which one line light source is arranged in each block (or each block and each hollow portion) of the light guide plate, but each block (or each block and each hollow portion) is shown. A plurality of line light sources may be arranged side by side. Moreover, you may divide | segment a line light source in the longitudinal direction of each block (or each block and each hollow part).

  Next, a surface light source and a liquid crystal display device according to a seventh embodiment of the present invention are described with reference to FIGS. 11 and 12 are diagrams showing the relationship between the writing timing of image data and the lighting timing of the light source in the liquid crystal display device of this embodiment.

  In the first to sixth embodiments described above, the structure of the surface light source is described. However, in each embodiment, the writing of the image data of the liquid crystal panel and the lighting timing of the light source such as an LED or a line light source are optimized. Therefore, it is possible to reduce tailing (moving image blur) of an image when displaying a moving image on the liquid crystal panel. An example is shown in FIG.

  FIG. 11 shows an example in which the vertical direction of the liquid crystal panel is divided into six, and writing of image data in one frame starts from the upper end of the display area, ends at the lower end, and the timing of lighting the LED accordingly. This is a schematic representation. As shown in FIG. 11, after the writing of the image data in the corresponding region is completed (the solid line pattern in FIG. 11), or immediately before the writing of the next image data starts after the writing is finished (broken line in FIG. 11). The light source is turned on in pulses.

  In the example of FIG. 11 above, the lighting time of the light source does not overlap with adjacent blocks, but may of course be overlapped. That is, the light source may be sequentially turned on except during the writing of the image data (ideally during the liquid crystal response).

  Also, the contrast can be improved by adjusting the luminous intensity of the light source in the corresponding region in accordance with the brightness of the image data. FIG. 12 shows an example, and when it is determined that the image is dark (low gradation) from the written image data, the brightness is lowered by narrowing the lighting pulse width of the light source, and conversely bright (high gradation). If it is determined, the brightness is increased by widening the lighting pulse width. This may be not the pulse width but the pulse height and a combination thereof.

  By increasing the number of divisions of the light guide plate, a great effect can be obtained by reducing the moving image blur and improving the contrast. In addition, since the light source only illuminates only the necessary area in a pulse shape, the light emission intensity of the light source can be weakened for dark image data, and it is possible to reduce power consumption compared to the case where all light is lit. Become.

  In each of the above-described embodiments, the case where the surface light source of the present invention is applied to a liquid crystal display device has been described. However, the present invention is not limited to the above-described embodiment, and any arbitrary light that requires uniform illumination light may be used. It can be applied to a lighting device.

  The present invention relates to an arbitrary illumination device that requires uniform illumination light, an arbitrary liquid crystal display device using the illumination device as a backlight, a computer monitor using the liquid crystal display device, a liquid crystal television, a mobile phone terminal, a GPS, and the like. It can be used for a terminal, a car navigation system, a game machine, a bank / convenience store terminal, a medical diagnostic device, and the like.

1-4, 8-10 Liquid crystal display device 11 Backlight 101, 201, 301, 401, 501, 601, 701 LED
102, 202, 302, 402 LED mounting substrate 103, 203, 303, 403 Light source 104, 204, 304, 404, 504, 504a-c, 604a-m, 804, 904, 1004a, 1004b, 1104a-e 105, 205, 305, 405, 805, 905, 1005 Sheets 106, 206, 306, 406, 806, 906, 1006 Liquid crystal panel 207, 907 Hollow part 209 Reflective layer 308, 1008 Diffuser plate 609 Filler 613 Condenser 710a, 710b Optical path 811, 911, 1011 Reflector 812, 912, 1012 Line light source 1105 Reflector 1101a-j White LED
1102a, 1102b LED array

Claims (7)

In the surface light source that illuminates the liquid crystal panel,
A light guide plate disposed on the back surface of the liquid crystal panel, and a plurality of light sources disposed on a surface of the light guide plate opposite to the liquid crystal panel,
The light guide plate guides light from the plurality of light sources and holds optical sheets, and when viewed from the normal direction of the liquid crystal panel, the light guide plate has a plurality of longitudinal directions parallel to one side of the liquid crystal panel. The plurality of blocks are divided into blocks, and the plurality of blocks are arranged with an interval between each other , and a reflective layer is formed on at least the surface of the hollow portion side of the adjacent blocks,
The light source is arranged in the longitudinal direction of each block of the light guide plate and a hollow portion between the blocks. The surface light source according to claim 1, wherein the light source is a line light source. 3. The surface light source according to claim 1, wherein each block of the light guide plate is divided in a thickness direction, and a diffusion layer is disposed between the divided blocks on both sides . 4. The light source is sequentially turned on in synchronization with writing of image data in a display area of the liquid crystal panel corresponding to each block of the light guide plate . 5. Surface light source. The light source, based on the brightness of the image data in the display area of the liquid crystal panel corresponding to each block of the light guide plate, in any one of claims 1 to 3, characterized in that the light intensity is adjusted The surface light source described. The light sources are sequentially turned on in synchronization with the writing of image data in the display area of the liquid crystal panel corresponding to each block of the light guide plate , and the light intensity is adjusted based on the brightness of the image data. The surface light source according to any one of claims 1 to 3 . A liquid crystal display device comprising the surface light source according to claim 1 as a backlight light source.

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