Display device and method for manufacturing the same

Abstract

The present invention addresses the problem of implementing a high-definition and high-contract display device by accurate local dimming. To solve the problem, the present invention adopts the following configuration. Provided is a display device comprising a display panel and a backlight, and characterized in that the backlight has a light source and an optical sheet group, the light source has a light source substrate 61 and LEDs 60 disposed on the light source substrate 61, the light source is divided into segments in plan view, at least one of the LEDs 60 is present in the segment, the light source substrate 61 and the LEDs 60 are covered with transparent resin 62, and a groove-shaped gap 70 is formed along a boundary between the segments in the transparent resin 62.

Description

[Technical Field]

[0001] The present invention relates to a display device having a backlight, and more particularly to a display device that uses local dimming to enable a high contrast screen. [Background technology]

[0002] A liquid crystal display device has a TFT substrate on which pixel electrodes and thin film transistors (TFTs) are formed in a matrix, an opposing substrate facing the TFT substrate, and a liquid crystal layer sandwiched between the TFT substrate and the opposing substrate. Images are formed by controlling the light transmittance of the liquid crystal molecules for each pixel.

[0003] On the other hand, in an organic EL display device, pixels each having a light-emitting element made of an organic EL layer, a driving TFT, a switching TFT, etc. are formed in a matrix, and an image is formed by controlling the light-emitting intensity of the organic EL layer for each pixel. Because organic EL display devices are self-emitting elements, they have excellent image contrast.

[0004] However, because the pixel size can be made smaller in LCD devices, LCD devices have superior definition. Therefore, local dimming has been developed as a method for improving the contrast of LCD devices. Prior art related to local dimming is available in, for example, Patent Document 1. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2017-116683 Summary of the Invention [Problem to be solved by the invention]

[0006] Display devices for VR (Virtual Reality) and medical use require images with higher resolution and contrast. When using local dimming in such display devices, more precise control of the local dimming is also required.

[0007] In order to perform local dimming more effectively and improve contrast in such a display device, it is necessary, for example, to reduce the area of the segment that serves as the unit of local dimming and to prevent the light from each segment from reaching adjacent segments.

[0008] Furthermore, if the area of a segment is reduced, it becomes difficult to place multiple LEDs in the segment. On the other hand, if only one LED is placed in each segment, it becomes difficult to uniformly distribute brightness, and the LED can be seen from the screen. If a diffusion sheet is placed to address this issue, for example, the diffusion sheet will cause the light from each segment to leak into adjacent segments, which can be a problem.

[0009] An object of the present invention is to solve such problems, to effectively perform local dimming, and to realize a high-definition, high-contrast screen in a display device having a backlight. [Means for solving the problem]

[0010] The present invention is intended to solve the above problems, and the main specific means are as follows.

[0011] (1) A display device having a display panel and a backlight, wherein the backlight has a light source and a group of optical sheets, the light source has a light source substrate and LEDs arranged on the light source substrate, the light source is divided into segments when viewed in a plane, each segment has at least one LED, the light source substrate and the LEDs are covered with a transparent resin, and the transparent resin has groove-shaped gaps formed along the boundaries of the segments.

[0012] (2) The display device according to (1), wherein a light guide plate is disposed between the group of optical sheets and the transparent resin, and the transparent resin is in contact with the light guide plate.

[0013] (3) The display device according to (1), wherein the groove-shaped gap is not formed in the corner portion of the segment.

[0014] (4) The display device according to (1), wherein the depth of the groove-shaped gap is smaller than the thickness of the transparent resin. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a plan view of a liquid crystal display device. [Figure 2] FIG. 1 is a cross-sectional view of a liquid crystal display device. [Figure 3] FIG. 10 is a plan view showing an example of segments in a liquid crystal display device in a local dimming operation. [Figure 4] FIG. 10 is a plan view of Comparative Example 1 using a blue LED. [Figure 5] FIG. 10 is a cross-sectional view of Comparative Example 1 using a blue LED. [Figure 6] FIG. 10 is a plan view of Comparative Example 2 using a white LED. [Figure 7] FIG. 10 is a cross-sectional view of Comparative Example 2 using a white LED. [Figure 8] 1 is a cross-sectional view showing the problems of Comparative Examples 1 and 2. FIG. [Figure 9] FIG. 2 is a cross-sectional view showing the operation of the first embodiment. [Figure 10] 3A to 3C are cross-sectional views showing a process for forming a groove-shaped gap in the transparent resin of Example 1. [Figure 11] FIG. 2 is a plan view of a light source substrate according to the first embodiment. [Figure 12] FIG. 1 is a cross-sectional view of Example 1. [Figure 13] 1 is a graph showing the effect of Example 1. [Figure 14] FIG. 2 is a detailed cross-sectional view of the light source substrate of the first embodiment. [Figure 15] FIG. 4 is a detailed cross-sectional view of a light source substrate showing another example of the first embodiment. [Figure 16] FIG. 10 is a plan view of a light source substrate for explaining a second embodiment. [Figure 17] FIG. 10 is a plan view of a light source substrate showing the configuration of a second embodiment. [Figure 18] FIG. 10 is a cross-sectional view of Example 3. [Figure 19] FIG. 10 is a plan view of a light source substrate showing the configuration of a fourth embodiment. [Figure 20] FIG. 10 is a plan view of a light source substrate showing the configuration of another example of the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] The present invention will be described in detail below using examples. [Example]

[0017] Fig. 1 is a plan view showing an example of a liquid crystal display device. In Fig. 1, a TFT substrate 100 and a counter substrate 200 are bonded with a sealant 16, with liquid crystal sandwiched between them. A display area 14 is formed in the area where the TFT substrate 100 and the counter substrate 200 overlap. In the display area 14, scanning lines 11 extend in the horizontal direction (x direction) and are arranged in the vertical direction (y direction). Video signal lines 12 extend in the vertical direction and are arranged in the horizontal direction. Pixels 13 are formed in the area surrounded by the scanning lines 11 and the video signal lines 12.

[0018] In Fig. 1, the portion where the TFT substrate 100 does not overlap with the counter substrate 200 is a terminal region 15. A flexible wiring substrate 17 is connected to the terminal region 15 to supply power and signals to the liquid crystal display panel. A driver IC that drives the liquid crystal display panel is mounted on the flexible wiring substrate 17. A backlight is arranged on the back of the TFT as shown in Fig. 2.

[0019] Fig. 2 is a cross-sectional view of a liquid crystal display device. In Fig. 2, a backlight 20 is disposed on the back surface of a liquid crystal display panel 10. The liquid crystal display panel 10 has the following configuration: a counter substrate 200, on which a black matrix and color filters are formed, is disposed opposite a TFT substrate 100, on which pixel electrodes, common electrodes, TFTs, scanning lines, video signal lines, etc. are formed. The TFT substrate 100 and the counter substrate 200 are bonded together at their peripheries with a sealant 16, and liquid crystal 300 is sealed inside.

[0020] The liquid crystal molecules are initially aligned by alignment films formed on the TFT substrate 100 and the counter substrate 200. When a voltage is applied between the pixel electrode and the common electrode, the liquid crystal molecules rotate, and an image is formed by controlling the light from the backlight 20 for each pixel. Since the liquid crystal 300 can only control polarized light, a lower polarizer 101 is placed below the TFT substrate 100, and only polarized light is incident on the liquid crystal 300. The light modulated by the liquid crystal 300 is analyzed by the upper polarizer 201, and an image is visible.

[0021] 2, a backlight 20 is disposed on the back surface of the liquid crystal display panel. The backlight 20 has a configuration in which a light guide plate 40 is disposed on a light source 30, and an optical sheet group 50 is disposed on top of that. There are two types of backlights 20 for display devices: a side light type in which light sources such as light emitting diodes (LEDs) that are light emitting elements are disposed on the side of the light guide plate, and a direct type in which light sources such as LEDs are disposed on the underside of the light guide plate. In the present invention, a direct type backlight is used.

[0022] In Fig. 2, a light guide plate 40 is disposed above the light source 30. The light guide plate 40 is made of transparent resin. The light guide plate 40 in Fig. 2 has the role of homogenizing the light from the LED, which is a point light source, by reflecting the light that has entered the light guide plate 40 at the interface.

[0023] A group of optical sheets 50 is disposed on the light guide plate 40. The group of optical sheets 50 may include a prism sheet, a diffusion sheet, etc. In addition, to obtain white light using a blue LED or the like as a light source, a color conversion sheet in which phosphors are dispersed in a resin sheet or a color conversion sheet using quantum dots may be used. Also, a polarized reflection sheet may be used to improve the efficiency of use of light from the backlight 20. The type of optical sheet to be used and the number of such optical sheets to be used are determined depending on the display device.

[0024] When displaying an image on an LCD, the bright areas transmit the backlight and the dark areas block the backlight. The contrast of the image is defined by the ratio of the bright and dark areas. In LCDs, the dark areas are created by blocking the light from the backlight with the liquid crystal. However, the liquid crystal does not completely block the backlight, and some light leaks through. This reduces the contrast.

[0025] Local dimming enables a deep black display by not illuminating dark areas with backlight. Therefore, high contrast can be achieved. Figure 3 is an example of a liquid crystal display device that illustrates a form of local dimming. Figure 3 is a plan view of the liquid crystal display device, and the configuration is the same as that described in Figure 1. In Figure 3, the display area 14 is divided by segments 141. The dotted lines in Figure 3 indicate the boundaries of the segments 141, but this is shown for convenience and the liquid crystal display panel does not actually have such boundaries. Light sources in the backlight are arranged at positions corresponding to each segment.

[0026] In Figure 3, segment (4, 2) is a bright area, and segment (5, 2) is a dark area. With local dimming, the light source for segment (4, 2), i.e., the LED, is turned on, and the light source for segment (5, 2), i.e., the LED, is not turned on. This results in a deep black display in segment (5, 2), achieving high contrast.

[0027] However, since there are no boundaries between the segments, depending on the brightness distribution of the segments, for example, the light from segment (4, 2) may reach segment (5, 2). In this case, the backlight will also illuminate segment (5, 2), which should display black, and the effect of local dimming will not be fully realized.

[0028] 4 and 5 show a comparative example 1 showing the configuration of a backlight that enables local dimming. In FIGS. 4 and 5, a blue LED 60 is used as the light source. FIG. 4 is a plan view showing the arrangement of the LEDs 60, which are light sources, in each segment 141 of the backlight. In FIG. 4, each segment 141 is separated by a dotted line. However, this dotted line is for convenience and does not actually separate the segments. The size of each segment is 4 mm square or less, and in the case of FIG. 5, it is, for example, 2 mm square. The size of the segments 141 in the following examples is similar. In FIG. 4, one LED 60 is arranged in each segment 141.

[0029] Fig. 5 is a cross-sectional view of a backlight in Comparative Example 1. In Fig. 5, LEDs 60 are arranged on a light source substrate 61, and transparent resin 62 is formed to cover the LEDs 60. A blue LED is used as the LED 60. For example, an acrylic resin or a silicone resin is used as the transparent resin 62. The transparent resin 62 is intended to protect the LEDs 60 and the electrodes and wiring formed on the light source substrate 61. The dotted lines drawn on the light source substrate 61 in Fig. 5 indicate the boundaries of segments for convenience.

[0030] A light guide plate 40 is disposed on a transparent resin 62. The light guide plate 40 is transparent, but it reflects light incident on the light guide plate 40 at the interface and functions to homogenize the light from the LEDs 60. A color conversion sheet 51 is disposed on the light guide plate 40. The color conversion sheet 51 is a transparent resin sheet in which a phosphor that receives blue light and emits yellow light is dispersed, and light that passes through the color conversion sheet 51 becomes white light. The thickness of the color conversion sheet 51 is, for example, 50 μm to 200 μm.

[0031] A diffusion sheet 53 is disposed on the color conversion sheet 51. The diffusion sheet 53 diffuses light from the light source 60 to uniformize the brightness. The thickness of the diffusion sheet 53 is, for example, 50 μm to 200 μm. A prism sheet 52 is disposed on the diffusion sheet 53. The prism sheet 52 is composed of prisms with triangular cross sections extending in the y direction and arranged in the x direction. The role of the prism sheet 52 is to improve light utilization efficiency by redirecting light emitted obliquely from the main surface of the color conversion sheet 51 in a direction perpendicular to the main surface of the color conversion sheet 51. In FIG. 5, there is only one prism sheet 52, but a prism sheet having a prism array extending in a direction perpendicular to the prism array of the prism sheet 52 in FIG. 5 may also be added. The thickness of the prism sheet is, for example, 50 microns for the prism array portion (i.e., the height of the prisms) and 70 microns for the base portion, totaling approximately 120 microns.

[0032] 6 and 7 show Comparative Example 2 in which a white LED 65 is used as the light source. FIG. 6 is the same as FIG. 4 except that the LED serving as the light source is a white LED 65. FIG. 7 is a cross-sectional view of the backlight in Comparative Example 2. In FIG. 7, a white LED 65 is disposed on a light source substrate 61, and a transparent resin 62 is formed to cover the white LED 65.

[0033] A light guide plate 40 is disposed on transparent resin 62. The role of the light guide plate 40 is the same as that described in Comparative Example 1. A diffusion sheet 53 is disposed on the light guide plate 40, and a color conversion sheet 51 is not disposed. This is because white LEDs 65 are used, so color conversion is not necessary. The role of the diffusion sheet 53 is the same as that described in FIG. 5. A prism sheet 52 is disposed on the diffusion sheet 53. The structure and function of the prism sheet are the same as those described in FIG. 5.

[0034] The problem with Comparative Examples 1 and 2 is that light from the LED 60 or 65 leaks into adjacent segments through the transparent resin 62 that covers the LED 60 or 65, the light guide plate 40, the color conversion sheet 51, and the diffusion sheet 53. In particular, there is a large amount of light leakage into adjacent segments through the transparent resin 62, which is close to the light source.

[0035] Fig. 8 is a cross-sectional view showing the problems with Comparative Examples 1 and 2. In Fig. 8, LEDs 60 are arranged on a light source substrate 61, and transparent resin 62 is formed to cover the LEDs 60. A light guide plate 40 is arranged on the transparent resin 62. The optical sheets above the light guide plate 40 are omitted. The dotted lines in Fig. 8 indicate the boundaries of the segments, but this is for convenience only, and no such lines actually exist.

[0036] The arrows in Figure 8 indicate the direction of light travel. Light from the LED 60 is emitted not only upward, but also sideways and diagonally. In Figure 8, the light emitted diagonally from the LED 60 is incident on an adjacent segment. Even when the adjacent segment displays black, this light is irradiated onto the display panel, making effective local dimming impossible.

[0037] FIG. 9 is a cross-sectional view showing the configuration and operation of this embodiment. The configuration in FIG. 9 is the same as that in FIG. 8, except that the transparent resin 62 is divided by groove-shaped gaps 70 at the boundary between the segments. The arrows in FIG. 9 indicate the direction of light emission from the LED 60. In FIG. 9, light emitted obliquely from the LED 60 is reflected by the groove-shaped gaps 70 in the transparent resin 60, and a significantly reduced amount of light enters the adjacent segment. This is because the difference in refractive index between the transparent resin 62 and air causes light to be reflected at the interface between the transparent resin 62 and the groove-shaped gaps 70. This minimizes the effect of light leakage on local dimming.

[0038] Therefore, the higher the refractive index of the transparent resin 62, the better. For example, acrylic resin, silicone resin, etc. can be used as the material of the transparent resin 62. In FIG. 9, the plane of the LED 60 is rectangular, e.g., square, and the width lx of the LED 60 is 0.1 mm to 0.5 mm. The thickness rt of the transparent resin is, e.g., 0.5 mm to 1 mm. The height lh of the LED 60 is, e.g., 0.3 mm to 0.5 mm.

[0039] The width gw of the groove gap 70 has a relatively large degree of freedom, but it is better to make it as small as possible within the range that can be processed. In other words, since light from the LED 60 does not reach the groove gap 70, the groove gap 70 portion becomes dark, and when observed from the surface of the transparent resin 62, this results in brightness unevenness. However, normally, the effects of the light guide plate 40, diffusion sheet 53, etc., placed on the transparent resin 62 disperse the influence of the groove gap 70, and brightness unevenness is not noticeable on the screen of the display panel. However, the fact remains that the narrower the width gw of the groove gap 70, the less likely brightness unevenness will occur.

[0040] FIG. 10 is a cross-sectional view showing a process for forming the transparent resin 62 in FIG. 9. In FIG. 10, the transparent resin 62 is processed by photolithography. In FIG. 10, a positive photosensitive resin is used as the material for the transparent resin 62. The photosensitive resin 62 is applied onto the light source substrate 61, covering the LEDs 60, and temporarily cured. Thereafter, only the portion 621 corresponding to the groove gap 70 is exposed using an exposure mask 400, and developed. Thereafter, the resin is finally cured.

[0041] 11 is a plan view of the light source substrate 61 thus formed. Groove-shaped gaps 70 are formed in the photosensitive resin 62 along the boundaries of the segments 141, and an LED 60 is disposed in the center of the segment 141. The size of each segment 141 is 4 mm square or less, for example, 2 mm square.

[0042] Fig. 12 is a cross-sectional view of a backlight according to the present invention that uses the light source substrate 61 shown in Fig. 11. In Fig. 12, the upper side from the light guide plate 40 is the same as Fig. 5, which shows Comparative Example 1. In Fig. 12, groove-like gaps 70 are formed in the transparent resin 62 that covers the LEDs 60 at the boundaries of the segments. Therefore, as explained in Fig. 9, light leakage to adjacent segments through the transparent resin 62 can be reduced.

[0043] FIG. 13 is a graph comparing light leakage to adjacent segments between Example 1 and Comparative Example 1. The data in the upper graph and the lower table in FIG. 13 are the same. In the graph in FIG. 13, the horizontal axis represents the distance from the center of the specific segment where the LED is placed, and the unit is the number of segments. The vertical axis represents the diameter of the LED (lx in FIG. 9). The vertical axis represents the relative luminance. In other words, the relative luminance is measured when the luminance at the center of the LED is set to 1. The luminance was measured above each of the prism sheets in FIG. 5 (Comparative Example 1) and FIG. 12 (Example 1).

[0044] The correspondence between the graph in Figure 13 and the table in Figure 13 is as follows: The "boundary" in the table corresponds to 0.5 or -0.5 on the horizontal axis of the graph, the "1 segment boundary" in the table corresponds to 1.5 or -1.5 on the horizontal axis of the graph, and the "2 segment boundary" in the table corresponds to 2.5 or -2.5 on the horizontal axis of the graph.

[0045] In the graph and table of FIG. 13, the brightness should theoretically be symmetrical across the center of a specific segment, but due to experimental error and other factors, it is asymmetrical. However, the trend can be discerned. Taking the average of the brightness in the positive direction of the horizontal axis and the brightness in the negative direction of the horizontal axis in the graph of FIG. 13 enables a more reasonable comparison. As shown in the graph and table of FIG. 13, light leakage to adjacent segments is reduced in Example 1 compared to Comparative Example 1. Therefore, Example 1 can perform more accurate local dimming.

[0046] The full-light luminance in the table of Fig. 13 is the luminance when the entire screen is displayed in white. In this case, it is almost the same in Example 1 and the comparative example. Note that the full-light luminance is about 1% higher in Example 1, but this can be considered to be because in Example 1, the amount of light that escapes to the outside of the screen when viewed from a plane is smaller in the segments on the periphery of the screen.

[0047] FIG. 14 is a detailed cross-sectional view showing the LED 60, transparent resin 62, groove gap 70, etc. The LED 60 is a blue LED. In FIG. 14, a light source substrate 61 is formed of, for example, epoxy resin. An electrode pad 612 connected to an anode 601 of the LED 60 and an electrode pad 613 connected to a cathode 602 of the LED 60 are formed of metal on the light source substrate 61. Various other wirings are formed on the light source substrate 61, but are omitted in FIG. 14. The LED 60 is flip-chip bonded to the electrode pads 612 and 613 of the light source substrate 61. The terminal electrodes 601 and 602 of the LED 60 face the electrode pads 612 and 613 of the light source substrate 61 and are connected via solder 615. The LED 60 is formed by bonding a p-type semiconductor and an n-type semiconductor, but in reality, various layers are formed to increase light-emitting efficiency.

[0048] In Figure 14, the LED 60 is covered and protected by a transparent resin 62. When a voltage is applied to the LED 60, light is emitted at the boundary between the p-type layer and the n-type layer. The light from the LED 60 is emitted not only upward but also laterally. Light emitted laterally enters adjacent segments and adversely affects local dimming operation. Therefore, as explained in Figure 9, a groove-like gap 70 is formed to reflect the light and reduce light leakage into adjacent pixels.

[0049] 14, for example, electrodes 612, 613, etc. are not protected by transparent resin 62 and are exposed to the outside air. If a material that corrodes easily is used as the electrode material, there is a risk of the electrodes being broken. In addition, since the transparent resin 62 is relatively thick, about 0.5 mm to 1 mm, it may be difficult to reduce the width gw of the groove-like gap 70.

[0050] On the other hand, light is emitted from the LED 60 at the junction between the p-type semiconductor and the n-type semiconductor. Therefore, it may be possible to obtain the effect of blocking light from the LED 60 without forming the groove gap 70 all the way to the bottom of the LED 60. In such cases, the groove gap 70 may be stopped midway rather than being formed deep enough to reach the surface of the electrode or light source substrate.

[0051] Fig. 15 is a cross-sectional view showing this example. In Fig. 15, the depth gd of the groove gap 70 is greater than half the thickness rt of the transparent resin 62, but is smaller than the thickness rt of the transparent resin 62. Alternatively, the depth of the groove gap 70 can be set to a value greater than the distance between the junction between the p-type semiconductor and the n-type semiconductor and the surface of the transparent resin 62, but smaller than the thickness rt of the transparent resin 62. [Example]

[0052] As explained in Example 1, when groove gaps 70 are formed along the boundaries of the segments, it is possible to reduce light leakage into adjacent segments, as explained in Fig. 9. On the other hand, because light from the LEDs 60 in the segments on both sides does not easily reach the groove gaps 70, the groove gaps 70 appear dark when viewed directly above the transparent resin 62. However, due to the effects of the light guide plate 40 and diffusion sheet 63, which are placed on the transparent resin 62, this brightness unevenness is usually not visible.

[0053] However, when the entire screen is displayed in white, the brightness decreases in the circled areas in Fig. 16, i.e., the corners of the segments, which may result in brightness unevenness. Fig. 16 is a plan view showing a state in which LEDs 60 and transparent resin 62 are formed on a light source substrate, and groove gaps 70 are formed in the transparent resin 62. As shown in Fig. 16, the corners are the areas most susceptible to the influence of groove gaps 70 on brightness.

[0054] FIG. 17 is a plan view showing the shape of groove gaps 70 formed in the transparent resin 62 to address this brightness unevenness. As shown in FIG. 17, the groove gaps 70 are not formed in the portions corresponding to the corners of the segments. In other words, if the groove gaps 70 were not formed, the light from the LEDs 60 would not be blocked, and brightness would not decrease. Furthermore, since the corners of the segments are far from the center of the LEDs 60, the amount of light leaking through the corners to adjacent pixels is small. Therefore, even if groove gaps 70 are not formed in the corners, the effect of local dimming is not significantly impaired.

[0055] The range in the corners where the groove gap 70 is omitted is determined by balancing the brightness unevenness during all-white display and the effect of local dimming. In other words, the range in which the groove gap 70 is formed is determined so that brightness unevenness does not occur during all-white display. For example, if the range in the corners where the groove gap 70 is omitted is s, experiments have shown that s should be in the range of approximately two to six times the width gw of the groove gap 70.

[0056] In this way, according to the configuration of the second embodiment, it is possible to prevent uneven brightness in all-white display and to improve the effect of local dimming. [Example]

[0057] In Examples 1 and 2, the case where a blue LED 60 is used as the light source has been described. However, the present invention can also be applied to the case where a white LED 65 is used. FIG. 18 is a cross-sectional view showing a backlight according to the present invention when a white LED 65 is used. The light source portion in FIG. 18 is the same as that in FIG. 12 of Example 1, except that the blue LED 60 has been replaced with a white LED 65. In FIG. 18, no color conversion sheet is present in the optical sheet group. This is because the light source is white light, and color conversion is not necessary. The other configurations in FIG. 18 are the same as those in FIG. 12.

[0058] A detailed cross-sectional view of the light source substrate when using white LEDs 65 is the same as that of FIG. 14 or FIG. 15 in the first embodiment, except that the blue LEDs 60 are replaced with white LEDs. The effects of these configurations are also the same as those described in FIGS. 14 and 15 in the first embodiment. Furthermore, the configuration described in the second embodiment can also be applied to the third embodiment. [Example]

[0059] In the first to third embodiments, the case where one LED 60 serving as a light source is used per segment has been described. However, the present invention can be applied without any problems to the case where multiple LEDs 60 are formed per segment. When multiple LEDs 60 are present per segment, the brightness of each LED 60 can be low, so the problem of bright spots caused by the LEDs 60 being visible from the screen side is unlikely to occur. Therefore, it may be possible to remove the diffusion sheet 63 from the group of optical sheets.

[0060] Fig. 19 is a plan view of a case where four LEDs 60 are used per segment. In Fig. 19, groove-like gaps 70 are formed along the boundaries of each segment. The other configurations are the same as Fig. 11 of Example 1. Also, the cross-sectional view is the same as Fig. 12 of Example 1, except that there are multiple LEDs.

[0061] Fig. 20 is a plan view showing an example in which four LEDs 60 are used per segment in the configuration of Example 2. Fig. 20 is the same as Fig. 17 of Example 2 except that four LEDs 60 exist per segment.

[0062] In this way, even when there are multiple LEDs 60 per segment, applying the present invention makes it possible to effectively perform local dimming. In addition, by controlling the range in which the groove gap 70 is formed, it is possible to effectively perform local dimming while preventing uneven brightness.

[0063] In the above description, the light guide plate 40 is disposed on the transparent resin 62 that covers the LEDs 60, 65. However, if there is no problem with uneven brightness, the light guide plate 40 is not necessarily required. In this case, the optical sheet group 50 is disposed directly on the transparent resin 62 that covers the LEDs 60, 65. [Explanation of symbols]

[0064] 10...display panel, 11...scanning line, 12...video signal line, 13...pixel, 14...display area, 15...terminal area, 16...sealing material, 17...flexible wiring board, 20...backlight, 30...light source, 40...light guide plate, 50...optical sheet group, 60...blue LED, 61...light source substrate, 62...transparent resin, 65...white LED, 70...groove-shaped gap, 100...TFT substrate, 101...lower polarizer, 200...counter substrate, 201...upper polarizer, 300...liquid crystal, 400...exposure mask, 601...anode, 602...cathode, 612...electrode pad, 613...electrode pad, 615...solder, 621...exposed area

Claims

1. A display device having a display panel and a backlight, the backlight includes a light source and a group of optical sheets; the light source includes a light source substrate and an LED disposed on the light source substrate; The light source is divided into segments when viewed in a plane, At least one of the LEDs is present in the segment; the light source substrate and the LED are covered with a positive photosensitive transparent resin that can be photolithographically processed by exposure and development; A display device characterized in that the transparent resin has groove-like gaps formed by removing a portion of the transparent resin along the boundaries of the segments.

2. 2. The display device according to claim 1, wherein a light guide plate is disposed between the group of optical sheets and the transparent resin, and the transparent resin is in contact with the light guide plate.

3. 2. The display device according to claim 1, wherein the groove-shaped gap is not formed at a corner portion of the segment.

4. 2. The display device according to claim 1, wherein the depth of the groove-shaped gap is smaller than the thickness of the transparent resin.

5. 2. The display device according to claim 1, wherein the groove-like gap is a space.

6. 2. The display device according to claim 1, wherein the LED is a blue LED, and the group of optical sheets includes a color conversion sheet.

7. 2. The display device according to claim 1, wherein each segment includes only one LED, and the group of optical sheets includes a diffusion sheet.

8. 2. The display device according to claim 1, wherein the group of optical sheets includes a prism sheet, a color conversion sheet, and a diffusion sheet.

9. 9. The display device according to claim 1, wherein the backlight is capable of performing a local dimming operation.

10. 9. The display device according to claim 1, wherein the display panel is a liquid crystal display panel.

11. A method for manufacturing a display device comprising: a display panel; a light source substrate; a light source having LEDs arranged on the light source substrate; and a backlight having a group of optical sheets, wherein the light source is divided into segments when viewed in a plane, and at least one LED is present in each segment, the light source substrate and the LEDs are covered with a transparent resin, and groove-like gaps are formed in the transparent resin along the boundaries of the segments, applying a positive photosensitive transparent resin onto the light source substrate so as to cover the LEDs; a step of temporarily curing the applied positive photosensitive transparent resin; a step of exposing only a portion of the pre-cured positive photosensitive transparent resin corresponding to the groove-shaped gap using an exposure mask; developing the exposed positive photosensitive transparent resin to remove the positive photosensitive transparent resin in the portion corresponding to the groove gap, thereby forming the groove gap; a step of completely curing the developed positive photosensitive transparent resin to form the transparent resin; A method for manufacturing a display device comprising the steps of:

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