Liquid crystal display device

Abstract

To provide a liquid crystal display device capable of suppressing deterioration in luminance uniformity.SOLUTION: An illumination part has a first illumination region with a first luminance and a second illumination region with a second luminance lower than the first luminance, and a liquid crystal display part includes a first region illuminated by the first illumination region, and a second region illuminated by the second illumination region. A pixel provided in the second region of the liquid crystal display device comprises a color filter having a first portion with a first transmittance and a second portion having a second transmittance higher than the first transmittance. A pixel provided in the first region comprises either a color filter having only the first portion, or a color filter having the first and second portions. In the pixel provided in the second region, the ratio of the second portion to the first and second portions is greater than the ratio of the second portion to the first and second portions in the pixel provided in the first region.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present disclosure relates to a liquid crystal display device.

Background Art

[0002] Conventionally, in a liquid crystal display device, a backlight is provided as an illumination device separately from the liquid crystal display panel. If there is luminance unevenness in the illumination device that supplies light to the display panel, there is a problem that the display uniformity of the liquid crystal display device deteriorates (see, for example, Patent Document 1).

[0003] Also, there is known a technique called local dimming in which the brightness of the backlight is controlled in units of areas according to the brightness and darkness of the screen to be displayed, and the contrast of the liquid crystal display device is increased.

[0004] In a local dimming backlight, among the divided areas, the outermost peripheral area has no light-emitting elements arranged, so the light leaking in is less than that in the areas other than the outermost peripheral area, and the luminance of the outermost peripheral area decreases. As a result, there is a problem that the in-plane luminance uniformity in the display area of the liquid crystal display device deteriorates.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Therefore, in a liquid crystal display device, it is required to suppress a decrease in luminance uniformity.

[0007] The present disclosure has been made in view of the above problems, and an object thereof is to provide a liquid crystal display device capable of suppressing a decrease in luminance uniformity.

Means for Solving the Problems

[0008] The liquid crystal display device according to the first embodiment of the present disclosure includes: a lighting unit having a first lighting area with a first luminance and a second lighting area with a second luminance lower than the first luminance; a liquid crystal display unit including a first area illuminated by the first lighting area and a second area illuminated by the second lighting area. The pixels provided in the second area of the liquid crystal display unit include a color filter having a first portion with a first transmittance and a second portion with a second transmittance higher than the first transmittance. i) The pixels provided in the first area include a color filter having only the first portion with the first transmittance, or ii) The pixels provided in the first area include a color filter having the first portion with the first transmittance and the second portion with the second transmittance, and in the pixels provided in the second area of the liquid crystal display unit, the ratio of the second portion to the first portion and the second portion is higher than the ratio of the second portion to the first portion and the second portion in the pixels provided in the first area.

Advantages of the Invention

[0009] According to the present disclosure, it is possible to provide a liquid crystal display device capable of suppressing a decrease in luminance uniformity.

Brief Description of the Drawings

[0010]

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Mode for Carrying Out the Invention

[0011] Hereinafter, with reference to the drawings, the liquid crystal display device according to this embodiment will be described.

[0012] (Embodiment 1) As shown in Figures 1 and 2, the liquid crystal display device 10 according to this embodiment includes a liquid crystal display panel (liquid crystal display unit) 100, a backlight (lighting unit) 200, and a control unit 300. The liquid crystal display panel 100 displays characters or images. The backlight 200 is provided so as to overlap the liquid crystal display panel 100 as shown in Figure 2, and irradiates the liquid crystal display panel 100 with light. The control unit 300 controls the display of the liquid crystal display unit 100 and the brightness of the backlight 200.

[0013] The liquid crystal display panel 100 is, for example, a horizontal electric field type color liquid crystal display panel actively matrix-driven by a TFT (Thin Film Transistor). As shown in FIG. 1, the liquid crystal display panel 100 has a display area 101 in which pixels including three sub-pixels of R, G, and B are arranged in a matrix, and a frame area 102 in which wirings, drive circuits, etc. are arranged and surround the display area 101. The display area 101 is an area capable of displaying characters, images, etc., and the frame area 102 is an area incapable of displaying characters, images, etc.

[0014] The backlight 200 of this embodiment is a local dimming type illumination, and as shown in FIG. 3, has a plurality of emission areas 200a. The illumination area 201 of the backlight 200 is an area composed of a plurality of emission areas 200a and is an area for illuminating the liquid crystal display panel 100. The backlight 200 includes a white LED (Light Emitting Diode) element, a reflection sheet, a diffusion sheet, a lighting circuit, etc. (none of which are shown). In the backlight 200 of this embodiment, for example, one or a plurality of white LED elements are arranged in each of the emission areas 200a.

[0015] FIG. 4(a) shows the illumination area 201 of the backlight 200. FIG. 4(a) corresponds to a plan view of the backlight 200 observed from the user side. Further, FIG. 4(b) is a graph showing the luminance at the B-B line shown in FIG. 4(a). The backlight 200 of this embodiment is composed of a plurality of emission areas 200a as shown in FIG. 3. Therefore, as shown in FIG. 4(b), the central illumination area 210 of the illumination area 201 has substantially the same luminance, but the luminance decreases as it moves away from the central illumination area 210 and toward the outer peripheral edge. The decrease in luminance is, for example, 20 to 30%.

[0016] Further, based on the luminance distribution in Fig. 4(b), compared with the luminance of the central illumination region 210, starting from the position where the luminance begins to decrease, the illumination region is set according to the degree of luminance decrease. Specifically, as shown in Fig. 4(a), from the position where the luminance begins to decrease, the region with a lower luminance compared to the central illumination region 210 is defined as the first illumination region 211. Also, the region with a lower luminance compared to the first illumination region 211 is defined as the second illumination region 212. Similarly, the region with a lower luminance compared to the second illumination region 212 is defined as the third illumination region 213, and the region with a lower luminance compared to the third illumination region 213 is defined as the fourth illumination region 214. In this embodiment, in the backlight 200, the luminance gradually decreases from the center toward the outer peripheral edge. Therefore, the central illumination region 210 is surrounded by the first illumination region 211, and the first illumination region 211 is surrounded by the second illumination region 212. Further, the second illumination region 212 is surrounded by the third illumination region 213, and the third illumination region 213 is surrounded by the fourth illumination region 214. Within the first illumination region 211 to the fourth illumination region 214, the luminance does not necessarily need to be uniform in the plane, and it is sufficient if the luminance is within a specific numerical range.

[0017] The control unit 300 is composed of a CPU (Central Processing Unit), a memory, etc., and controls the display of the liquid crystal display panel 100 and the luminance of the backlight 200. The functions of the control unit 300 are realized, for example, by the CPU executing a program stored in the memory.

[0018] Next, the display region 101 of the liquid crystal display panel 100 is shown in Fig. 5. In this embodiment, as will be described in detail later, the transmittances of the color filters provided in the sub-pixels of the pixels PX to PX4 in the display region 101 are different from each other. The transmittance of the color filter is determined according to the luminance of the illumination region 201 of the backlight 200 that illuminates the display region 101.

[0019] First, the central region 110 of the display area 101 is illuminated by the central illumination region 210 of the illumination area 201. The first region 111 of the display area 101 is illuminated by the first illumination region 211, and the second region 112 of the display area 101 is illuminated by the second illumination region 212. Similarly, the third region 113 of the display area 101 is illuminated by the third illumination region 213, and the fourth region 114 of the display area 101 is illuminated by the fourth illumination region 214.

[0020] As described above, in the backlight 200, the luminance decreases in the order of the central illumination region 210, the first illumination region 211, the second illumination region 212, the third illumination region 213, and the fourth illumination region 214. Therefore, in the liquid crystal display panel 100, the light transmittance from the backlight 200 is increased in the order of the central region 110, the first region 111, the second region 112, the third region 113, and the fourth region 114. As an example, the luminance of the backlight 200 decreases by 20 - 30% in the peripheral portion compared to the central portion. By adjusting the transmittance of the liquid crystal display panel 100, it is preferable that the difference in surface luminance of the liquid crystal display device 10 is within 15%.

[0021] Next, the pixel PX provided in the central region 110 is shown in FIG. 6(a). FIG. 6(b) shows the pixel PX1 provided in the first region 111 in FIG. 6(b), the pixel PX2 provided in the second region 112 in FIG. 6(c), the pixel PX3 provided in the third region 113 in FIG. 6(d), and the pixel PX4 provided in the fourth region 114 in FIG. 6(e). Further, FIG. 7(a) is a cross-sectional view taken along line VIIA - VIIA shown in FIG. 6(a). FIG. 7(b) is a cross-sectional view taken along line VIIB - VIIB shown in FIG. 6(b), FIG. 7(c) is a cross-sectional view taken along line VIIC - VIIC shown in FIG. 6(c), FIG. 7(d) is a cross-sectional view taken along line VIID - VIID shown in FIG. 6(d), and FIG. 7(e) is a cross-sectional view taken along line VIIE - VIIE shown in FIG. 6(e). In the present embodiment, as an example, a configuration in which a region with a high transmittance is provided only in the G color filter among the RGB color filters will be described.

[0022] First, as shown in FIGS. 7(a) to 7(e), the liquid crystal display panel 100 includes an active matrix substrate 103, a counter substrate 104, and liquid crystal LC. The counter substrate 104 is bonded to the active matrix substrate 103 by a sealing material (not shown). Further, the liquid crystal display panel 100 includes a polarizing plate (not shown) provided on the lower surface of the active matrix substrate 103 and a polarizing plate (not shown) provided on the upper surface of the counter substrate 104. The counter substrate 104 is, for example, a glass substrate. As shown in FIG. 4, a color filter 120, an overcoat film 106, and an alignment film (not shown) are provided on the surface of the counter substrate 104 facing the active matrix substrate 103. In this embodiment, the overcoat film 106 is formed thick. This prevents the occurrence of disclination in the pixel at the step due to the second portion 122 of the color filter 120.

[0023] The active matrix substrate 103 is, for example, a glass substrate. Pixel electrodes, gate wirings, data wirings, switching elements, etc. (all not shown) are provided on the surface of the active matrix substrate 103 facing the counter substrate 104. In FIGS. 7(a) to 7(e), for convenience of explanation, these switching elements, pixel electrodes, etc. are collectively shown as an electrode formation layer 107.

[0024] As shown in FIG. 6(a), the pixel PX provided in the central region 110 includes an R-color sub-pixel SPR, a G-color sub-pixel SPG, and a B-color sub-pixel SPB. In this embodiment, a high transmittance region is provided in the color filter 120 of the G-color sub-pixel SPG. Also, among the sub-pixels SPG, the displayable region is the pixel region PR partitioned by the black matrix BM.

[0025] As shown in FIG. 6(a), in pixel PX, the color filter 120 in the pixel region PR is composed of only the first portion 121 having a standard film thickness and a first transmittance. In other words, when pixel PX is viewed in plan view from the user side, in the pixel region PR, the ratio of the area occupied by the second portion 122 is zero. Also, as shown in FIG. 7(a), the color filter is composed of only the first portion 121.

[0026] Next, in pixel PX1 provided in the first region 111 surrounding the central region 110, the color filter 120 is composed of a first portion 121 having a first transmittance and a second portion 122 having a second transmittance higher than the first transmittance. As shown in FIG. 6(b), the pixel region PR includes the first portion 121 and the second portion 122. When pixel PX1 is viewed in plan view, the ratio of the area of the second portion 122 to the combined area of the first portion 121 and the second portion 122 is higher compared to pixel PX. Therefore, the color filter 120 of pixel PX1 has a higher transmittance than the color filter 120 of pixel PX. Also, as shown in FIG. 7(b), in pixel PX1, the film thickness of the second portion 122 of the color filter 120 is formed thinner than the first portion 121.

[0027] Furthermore, in pixel PX2 provided in the second region 112 surrounding the first region 111, the color filter 120 is composed of a first portion 121 having a first transmittance and a second portion 122 having a second transmittance higher than the first transmittance. As shown in FIG. 6(c), in the pixel region PR of pixel PX2, more of the second portion 122 is included compared to pixel PX1. Therefore, when pixel PX2 is viewed in plan view, the ratio of the area of the second portion 122 to the combined area of the first portion 121 and the second portion 122 is higher compared to pixel PX1. For this reason, the color filter 120 of pixel PX2 has a higher transmittance than the color filter 120 of pixel PX1. Also, as shown in FIG. 7(c), in pixel PX2 as well, the film thickness of the second portion 122 of the color filter 120 is formed thinner than the first portion 121.

[0028] Furthermore, as shown in FIG. 6(d), even in the pixel PX3 provided in the third region 113 surrounding the second region 112, the color filter 120 is composed of a first portion 121 having a first transmittance and a second portion 122 having a second transmittance higher than the first transmittance. As shown in FIG. 6(c), when the pixel PX3 is viewed in plan view, the ratio of the area of the second portion 122 to the combined area of the first portion 121 and the second portion 122 is higher compared to the pixel PX2. Therefore, the color filter 120 of the pixel PX3 has a higher transmittance than the color filter 120 of the pixel PX2. Also, as shown in FIG. 7(d), even in the pixel PX3, the film thickness of the second portion 122 of the color filter 120 is formed thinner than that of the first portion 121.

[0029] Note that the difference in the thickness of the color filter 120 as shown in FIGS. 7(b) to 7(d) can be manufactured by using a halftone mask.

[0030] In addition, as shown in FIGS. 6(e) and 7(e), in the pixel PX4 provided in the fourth region 114 surrounding the third region 113, the color filter 120 is composed only of the second portion 122 having the second transmittance. In other words, when the pixel PX4 is viewed in plan view from the user side, in the pixel region PR, the ratio of the area occupied by the second portion 122 is 1, and the transmittance of the color filter 120 of the pixel PX4 is higher than that of the pixel PX3.

[0031] In this embodiment, in the pixels PX to PX4, by sequentially increasing the ratio of the area of the second portion 122 having a transmittance higher than that of the first portion 121 with respect to the area when the pixel region PR is viewed in plan view, the transmittance can be increased from the pixel PX to the pixel PX4.

[0032] In the liquid crystal display device 10 of the present embodiment, in pixels PX1 to PX4 provided in the first region 111 to the fourth region 114 provided in the liquid crystal display panel 100, a second portion 122 having a high light transmittance of the backlight 200 is provided. Thereby, the decrease in the luminance of the backlight 200 is compensated for by the liquid crystal display panel 100, and as a result, the in-plane uniformity of the luminance on the surface of the liquid crystal display device 10 can be improved. Further, by gradually increasing the ratio of the second portion 122 having a high transmittance from the first region 111 to the fourth region 114 in accordance with the decrease in luminance, the decrease in the luminance on the surface of the liquid crystal display device 10 can be suppressed, and the in-plane uniformity can be improved.

[0033] Also, in the liquid crystal display device 10 of the present embodiment, in order to improve the luminance by increasing the transmittance of the color filter, it is not necessary to brighten the backlight 200, and the power consumption is not increased.

[0034] Furthermore, in the liquid crystal display device 10 of the present embodiment, it is possible to suppress a decrease in luminance at the outer peripheral edge of the display region 101. For example, when a conventional liquid crystal display device is used as a tiling display, if a low-luminance region is located at the periphery of the liquid crystal display device, there is a problem that the seam between the displays is conspicuous. However, in the liquid crystal display device 10 of the present embodiment, since it is possible to suppress the reduction in luminance at the periphery of the display region 101, it is also possible to obtain an effect that the seam between the displays can be made less conspicuous.

[0035] In this embodiment, a configuration in which a second portion with a high transmittance is provided for G among RGB has been described as an example. However, the color for which the second portion with a high transmittance is provided is not limited to G. For at least one color of the color filters of R, G, and B, the second portion may be provided. That is, the second portion may be provided only for one color of the color filters of R, G, and B, or for any two colors of the color filters, or for all three colors of the color filters. However, due to the change in the thickness of the color filter, the chromaticity also changes. The change in chromaticity is preferably within a range that is difficult for the user to visually recognize. Although there are differences depending on the materials used, G is the least likely to have a change in chromaticity due to a change in film thickness that is visually recognizable, and next, R also has a tendency for a change in chromaticity due to a change in film thickness to be less visually recognizable. For this reason, it is preferable to provide the second portion for the G color filter, and next, it is preferable to provide it for the R color filter.

[0036] Also, in this embodiment, a configuration in which the planar shape of the second portion 122 with a high transmittance is a square is given as an example. However, the planar shape of the second portion 122 is arbitrary and may be, for example, a polygon, a circle, an ellipse, or the like.

[0037] (Embodiment 2) The liquid crystal display device 10 according to Embodiment 2 will be described below. The feature of this embodiment lies in that the arrangement of the first portion 121 and the second portion 122 of the color filter 120 is different from that of Embodiment 1. For features common to Embodiment 1, the same reference numerals are given and detailed descriptions are omitted.

[0038] The pixels PX1 to PX3 according to this embodiment are shown in FIGS. 8(a) to 8(c). FIGS. 8(a) to 8(c) respectively correspond to FIGS. 6(b) to 6(d) of Embodiment 1. The pixels PX1 to PX3 in FIGS. 8(a) to 8(c) are respectively provided in the first region 111, the second region 112, and the third region 113. Note that since the pixels PX and PX4 have the same configuration as in Embodiment 1, the description thereof is omitted.

[0039] In this embodiment, a second portion 122 is provided so as to extend from the center of the pixel region PR toward both upper and lower ends. As shown in FIG. 8(a), in the color filter 120 of the pixel PX1, the second portion 122 with a high transmittance is provided in the central portion of the pixel PX1, and the first portion 121 with a low transmittance is provided above and below the second portion 122. In particular, the first portion 121 and the second portion 122 are arranged to be line-symmetric about the center line in the short-side direction of the pixel region PR shown in FIG. 8(a). By arranging in this way, the ratio of the area of the second portion 122 to the total area of the first portion 121 and the second portion 122 can be made the same in the upper half region and the lower half region of the pixel region PR. Further, as shown in FIGS. 8(b) and (c), when increasing the ratio of the second portion 122, the area of the second portion 122 provided in the central portions of the pixels PX2 and PX3 is increased.

[0040] FIG. 9 is a diagram for explaining the effect of this embodiment. As shown in FIG. 9, the electrode is bent at the central portion of the pixel, and the pixel has a multi-domain structure. In this case, in the upper domain, the ratio occupied by the second portion 122 with respect to the first portion 121 and the second portion 122 is made the same as the ratio occupied by the second portion 122 with respect to the first portion 121 and the second portion 122 in the lower domain.

[0041] It is known that light on the short-wavelength side appears strong when viewing the liquid crystal from the long-axis direction, and light on the long-wavelength side appears strong when viewing from the uniaxial direction. When the first portion 121 and the second portion 122 are provided as shown in FIG. 9, the transmittances of the upper domain and the lower domain can be made equal. Therefore, there is no difference in the color when viewed from the A direction and the color when viewed from the B direction. Thereby, it is possible to prevent the occurrence of color difference due to the second portion 122 with a high transmittance within the pixel.

[0042] In this way, making the ratio occupied by the second portion 122 with respect to the first portion 121 and the second portion 122 the same within each domain is particularly advantageous in the case of a multi-domain structure.

[0043] (Embodiment 3) The liquid crystal display device 10 according to Embodiment 3 will be described below. The feature of this embodiment lies in that the arrangement of the first portion 121 and the second portion 122 of the color filter 120 is different from those of Embodiments 1 and 2. For the features common to Embodiments 1 and 2, the same reference numerals are used and the detailed description is omitted.

[0044] The pixels PX1 to PX3 according to this embodiment are shown in FIGS. 10(a) to 10(c). FIGS. 10(a) to 10(c) respectively correspond to FIGS. 6(b) to 6(d) of Embodiment 1. The pixels PX1 to PX3 in FIGS. 10(a) to 10(c) are provided in the first region 111, the second region 112, and the third region 113, respectively. Note that since the pixels PX and PX4 have the same configuration as in Embodiment 1, the description thereof is omitted.

[0045] In this embodiment, as shown in FIGS. 10(a) to 10(c), a plurality of second portions 122 are arranged in a stripe shape. Thereby, the first portion 121 and the second portion 122 can be arranged with a fine pitch. In FIGS. 10(a) to 10(c), stripes extending in the short side direction of the pixel are taken as an example, but stripes extending in the long side direction or in an oblique direction may also be used.

[0046] When the pitch between the first portion 121 and the second portion 122 of the color filter 120 is large, a luminance difference may be visually recognized as streak-like unevenness. In such a case, there is a concern that when the pitch between the thin film portion and the standard film thickness portion of the color resist is large, the luminance difference is visually recognized as streak-like unevenness. By providing the second portion 122 at a plurality of locations as in this embodiment, the pitch between the first portion 121 and the second portion 122 becomes fine, and it is possible to prevent streak-like unevenness from being visually recognized.

[0047] (Embodiment 4) The liquid crystal display device 10 according to Embodiment 4 will be described below. In the above-described embodiment, the transmittance was made different by changing the thicknesses of the first portion 121 and the second portion 122 of the color filter 120. However, in this embodiment, the transmittance is made different by using different materials for the first portion and the second portion. Regarding the features common to the above-described embodiment, the same reference numerals are given and detailed description thereof is omitted.

[0048] The pixels PX to PX4 according to this embodiment are shown in FIGS. 11(a) to 11(e). FIGS. 11(a) to 11(e) respectively correspond to the line cross-sectional views described in FIGS. 6(a) to 6(e) of Embodiment 1. The pixels PX to PX4 in FIGS. 11(a) to 11(e) are provided in a central region 110, a first region 111, a second region 112, a third region 113, and a fourth region 114, respectively.

[0049] In this embodiment, in pixels PX1 to PX3, the color filters 125 each have the same planar shape as in FIGS. 6(b) to 6(d) of Embodiment 1. Also, as shown in FIGS. 11(b) to 11(d), the color filter 125 includes a first portion 126 having a first transmittance and a second portion 127 having a second transmittance higher than the first transmittance. In this embodiment, the second portion 127 is formed of a material having a higher light transmittance with the same film thickness as compared with the first portion 126. As shown in FIGS. 11(b) to 11(d), the first portion 126 and the second portion 127 of the color filter 125 are formed with the same film thickness.

[0050] When the materials are made different between the first portion 126 and the second portion 127 as in this embodiment, it is necessary to prepare two types of resists for forming the color filter and form films by different processes. However, since the film thickness is the same, there is an advantage that it is not necessary to use a halftone mask.

[0051] Also, in the color filters 125 within the pixels PX1 to PX3, since no step is generated, an effect of being able to reduce the possibility of occurrence of disclination can be obtained.

[0052] (Embodiment 5) The liquid crystal display device 10 according to Embodiment 5 will be described below. In Embodiment 1 described above, the overcoat film 106 was formed thick with respect to the color filter 120 so as not to cause a step in the overcoat film 106. However, in this embodiment, there is a step in the overcoat film 108, and the cell gap is widened in the region where the second portion 122 is provided. Regarding the features common to the above-described embodiments, the same reference numerals are given, and detailed descriptions thereof are omitted.

[0053] The pixels PX to PX4 according to this embodiment are shown in FIGS. 12(a) to 12(e). FIGS. 12(a) to 12(e) respectively correspond to the line cross-sectional views described in FIGS. 6(a) to 6(e) of Embodiment 1. The pixels PX to PX4 in FIGS. 12(a) to 12(e) are provided in the central region 110, the first region 111, the second region 112, the third region 113, and the fourth region 114, respectively.

[0054] In this embodiment, in pixels PX1 to PX3, the color filters 120 each have the same planar shape as in FIGS. 6(b) to 6(d) of Embodiment 1. Further, as shown in FIGS. 12(b) to 12(d), the color filter 120 includes a first portion 121 having a first transmittance and a second portion 122 having a second transmittance higher than the first transmittance. In this embodiment, the second portion 122 is formed with a thinner film thickness than the first portion 121, similar to Embodiment 1. Due to the difference in the film thickness between the first portion 121 and the second portion 122, a step is generated in the overcoat film 108. The cell gap in the region where the first portion 121 is provided is G1, and the cell gap in the region where the second portion 122 is provided is G2, and G2 is larger than G1 (G2 > G1). Also, in pixel PX4, which is entirely the second portion 122, the cell gap is G2.

[0055] In the region where the cell gap increases, the transmittance of light tends to increase. Therefore, by increasing the cell gap in the region where the second portion 122 is provided, it is possible to further increase the transmittance.

[0056] Therefore, in the liquid crystal display device of the present embodiment, the light transmittance can be further increased in pixels PX1 to PX4.

[0057] (Embodiment 6) The liquid crystal display device 10 according to Embodiment 6 will be described below. In the above-described Embodiment 1, the configuration in which a second portion having a high transmittance is provided for one color of color filter among R, G, and B was described as an example. In this embodiment, a second portion having a high transmittance is provided for two or more colors of R, G, and B, and the area ratio of the second portion in each pixel of R, G, and B is made different. For the features common to the above-described embodiments, the same reference numerals are given and detailed descriptions are omitted.

[0058] Pixels PX to PX4 according to this embodiment are shown in FIGS. 13(a) to 13(e). As shown in FIG. 13(a), in pixel PX, the color filter 120 in the pixel region PR1 of the R-color sub-pixel SPR, the pixel region PR2 of the G-color sub-pixel SPG, and the pixel region PR3 of the B-color sub-pixel SPB is composed only of the first portion 121 having a standard film thickness and a first transmittance. In other words, when pixel PX is viewed in a plan view from the user side, the ratio of the area occupied by the second portion 122 in pixel regions PR1 to PR3 is zero. FIG. 14(a) is a cross-sectional view taken along line XIVa-XIVa of the sub-pixel SPR shown in FIG. 13(a). FIG. 14(b) is a cross-sectional view taken along line XIVb-XIVb of the sub-pixel SPG shown in FIG. 13(a). FIG. 14(c) is a cross-sectional view taken along line XIVc-XIVc of the sub-pixel SPB shown in FIG. 13(a). As shown in FIGS. 14(a) to 14(c), the color filters of R, G, and B are composed only of the first portion 121.

[0059] Next, in pixel PX1, the color filter 120 is composed of a first portion 121 having a first transmittance and a second portion 122 having a second transmittance higher than the first transmittance. As shown in FIG. 13(b), the pixel regions PR1 and PR2 include the first portion 121 and the second portion 122. FIG. 14(d) is a cross-sectional view taken along line XIVd-XIVd of the sub-pixel SPR shown in FIG. 13(b). Further, FIG. 14(e) is a cross-sectional view taken along line XIVe-XIVe of the sub-pixel SPG shown in FIG. 13(b). Further, FIG. 14(f) is a cross-sectional view taken along line XIVf-XIVf of the sub-pixel SPB shown in FIG. 13(b). As shown in FIGS. 14(d) to (f), the B-color color filter is composed of only the first portion 121, and the R- and G-color color filters are composed of the first portion 121 and the second portion 122. In pixel PX1, the film thickness of the second portion 122 of the color filter 120 is formed thinner than that of the first portion 121. When pixel PX1 is viewed in plan view, in pixel regions PR1 and PR2, the ratio of the area of the second portion 122 to the combined area of the first portion 121 and the second portion 122 is higher compared to pixel PX. Therefore, the color filter 120 of pixel PX1 has a higher transmittance than the color filter 120 of pixel PX. Here, the ratio of the area of the second portion 122 in pixel region PR1 and the ratio of the area of the second portion 122 in pixel region PR2 are not the same, and the ratio of the area of the second portion 122 in pixel region PR2 is larger. Further, in pixel region PR3, similar to pixel PX, the ratio of the area occupied by the second portion 122 is zero. Therefore, the ratio of the area of the second portion 122 in pixel region PR3 is different from the ratio of the area of the second portion 122 in pixel regions PR1 and PR2.

[0060] Furthermore, in pixel PX2, the color filter 120 is composed of a first portion 121 having a first transmittance and a second portion 122 having a second transmittance higher than the first transmittance. As shown in FIG. 13(c), in pixel regions PR1 and PR2 of pixel PX2, compared with pixel PX1, more of the second portion 122 is included. Furthermore, in pixel region PR3, compared with pixel PX1, in addition to the first portion 121, the second portion 122 is included. Therefore, when pixel PX2 is viewed in plan view, the ratio of the area of the second portion 122 to the combined area of the first portion 121 and the second portion 122 is higher compared with pixel PX1. For this reason, the color filter 120 of pixel PX2 has a higher transmittance than the color filter 120 of pixel PX1. Here, the ratios of the areas occupied by the second portion 122 in each of pixel regions PR1, PR2, and PR3 are not the same, and the ratio of the area occupied by the second portion 122 is larger in the order of pixel regions PR3, PR1, and PR2. FIG. 14(g) is a cross-sectional view taken along line XIVg-XIVg of the sub-pixel SPR shown in FIG. 13(c). Also, FIG. 14(h) is a cross-sectional view taken along line XIVh-XIVh of the sub-pixel SPG shown in FIG. 13(c). Also, FIG. 14(i) is a cross-sectional view taken along line XIVi-XIVi of the sub-pixel SPB shown in FIG. 13(c). As shown in FIGS. 14(g) to (i), the color filters for R, G, and B are composed of the first portion 121 and the second portion 122, and also in pixel PX2, the film thickness of the second portion 122 of the color filter 120 is formed thinner than that of the first portion 121.

[0061] Furthermore, as shown in FIG. 13(d), also in pixel PX3, the color filter 120 is composed of a first portion 121 having a first transmittance and a second portion 122 having a second transmittance higher than the first transmittance. When pixel PX3 is viewed in plan view, the ratio of the area of the second portion 122 to the combined area of the first portion 121 and the second portion 122 is higher compared to pixel PX2 shown in FIG. 13(c). For this reason, the color filter 120 of pixel PX3 has a higher transmittance than the color filter 120 of pixel PX2. Here, the ratio of the area occupied by the second portion 122 in each of pixel regions PR1, PR2, and PR3 is not the same as in pixel PX2, and the ratio of the area occupied by the second portion 122 is large in the order of pixel regions PR3, PR1, and PR2. FIG. 15(j) is a cross-sectional view taken along line XVj-XVj of the sub-pixel SPR shown in FIG. 13(d). Also, FIG. 15(k) is a cross-sectional view taken along line XVk-XVk of the sub-pixel SPG shown in FIG. 13(d). Also, FIG. 15(l) is a cross-sectional view taken along line XVl-XVl of the sub-pixel SPB shown in FIG. 13(d). As shown in FIGS. 15(j) to (l), the color filters for R, G, and B are composed of the first portion 121 and the second portion 122, and also in pixel PX3, the film thickness of the second portion 122 of the color filter 120 is formed thinner than the first portion 121.

[0062] In addition, as shown in FIG. 13(e), in pixel PX4, color filter 120 includes a first portion 121 having a first transmittance in pixel regions PR1 and PR3 except for pixel region PR2, and a second portion 122 having a second transmittance higher than the first transmittance. In contrast, in pixel region PR2, it is composed only of the second portion 122 having the second transmittance. When pixel PX4 is viewed in plan view, the ratio of the area of the second portion 122 to the combined area of the first portion 121 and the second portion 122 in pixel regions PR1 and PR3 is higher than that of pixel PX3 shown in FIG. 13(d). Further, in pixel region PR2, the ratio of the area occupied by the second portion 122 is 1, and the transmittance of color filter 120 of pixel PX4 is higher than that of pixel PX3. FIG. 15(m) is a cross-sectional view taken along line XVm-XVm of the sub-pixel SPR shown in FIG. 13(e). Also, FIG. 15(n) is a cross-sectional view taken along line XVn-XVn of the sub-pixel SPG shown in FIG. 13(e). Also, FIG. 15(o) is a cross-sectional view taken along line XVo-XVo of the sub-pixel SPB shown in FIG. 13(e). As shown in FIGS. 15(m) to (o), the color filters for R and B are composed of the first portion 121 and the second portion 122, and the color filter for G is composed only of the second portion 122. Also in pixel PX4, the film thickness of the second portion 122 of color filter 120 is formed thinner than that of the first portion 121.

[0063] In this embodiment, in pixels PX to PX4, by increasing in order the ratio of the area of the second portion 122 having a transmittance higher than that of the first portion 121 with respect to the areas of pixel regions PR1, PR2, and PR3 when viewed in plan view, the transmittance can be increased from pixel PX to pixel PX4. Further, in pixel regions PR1, PR2, and PR3, the ratios of the area of the second portion 122 are made different from each other. By providing a second portion with a high transmittance for the R, G, and B color filters, the thickness of the color filter changes, and due to this change in the thickness of the color filter, a change also occurs in the chromaticity. This change in chromaticity is preferably within a range that is difficult for the user to visually recognize. Here, G has the least visible change in chromaticity due to the change in film thickness, and next, R tends to have a less visible change in chromaticity due to the change in film thickness. Therefore, the ratio of the second portion is changed by the color filter, that is, the change in the ratio of the second portion of the G-color filter is made the largest, next, the change in the ratio of the second portion of the R-color filter is made large, and the change in the ratio of the second portion of the B-color filter is made the smallest. Thereby, within a range where the change in chromaticity is suppressed and the change in chromaticity is not visually recognized, the transmittance can be increased from pixel PX to pixel PX4.

[0064] (Embodiment 7) The liquid crystal display device 10 according to Embodiment 7 will be described below. In the above-described Embodiment 6, a configuration in which a second portion having a high transmittance is provided in two or more of R, G, and B, and the area ratios of the second portions in the respective pixels of R, G, and B are made different from each other was described as an example. However, in this embodiment, a second portion having a high transmittance is provided in two or more of R, G, and B, and the film thickness difference between the standard film thickness portion which is the first portion and the thinning portion which is the second portion in each pixel of R, G, and B is made different. For features common to the above-described embodiments, the same reference numerals are given, and detailed descriptions thereof are omitted.

[0065] The pixels PX to PX4 according to this embodiment are shown in FIGS. 16(a) to 16(e). As shown in FIG. 16(a), in pixel PX, the color filters 120 in the pixel region PR1 of the sub-pixel SPR of the R color, the pixel region PR2 of the sub-pixel SPG of the G color, and the pixel region PR3 of the sub-pixel SPB of the B color are composed of only the first portion 121 having a standard film thickness and a first transmittance. In other words, when the pixel PX is viewed in plan view from the user side, the ratio of the area occupied by the second portion 122 in the pixel regions PR1 to PR3 is zero. FIG. 17(a) is a cross-sectional view taken along line XVIIa-XVIIa of the sub-pixel SPR shown in FIG. 16(a). Further, FIG. 17(b) is a cross-sectional view taken along line XVIIb-XVIIb of the sub-pixel SPG shown in FIG. 16(a). Further, FIG. 17(c) is a cross-sectional view taken along line XVIIc-XVIIc of the sub-pixel SPB shown in FIG. 16(a). As shown in FIGS. 17(a) to 17(c), the color filters of R, G, and B are composed of only the first portion 121.

[0066] Next, in pixel PX1, color filter 120 is composed of a first portion 121 having a first transmittance and a second portion 122 having a second transmittance higher than the first transmittance. As shown in FIG. 16(b), pixel regions PR1, PR2, and PR3 include the first portion 121 and the second portion 122. When pixel PX1 is viewed in plan view, in pixel regions PR1, PR2, and PR3, the ratio of the area of the second portion 122 to the combined area of the first portion 121 and the second portion 122 is the same and is higher compared to pixel PX. Therefore, color filter 120 of pixel PX1 has a higher transmittance than color filter 120 of pixel PX. FIG. 17(d) is a cross-sectional view taken along line XVIId-XVIId of the sub-pixel SPR shown in FIG. 16(b). Further, FIG. 17(e) is a cross-sectional view taken along line XVIIe-XVIIe of the sub-pixel SPG shown in FIG. 16(b). Further, FIG. 17(f) is a cross-sectional view taken along line XVIIf-XVIIf of the sub-pixel SPB shown in FIG. 16(b). As shown in FIGS. 17(d) to (f), the color filters 120 for R, G, and B are composed of the first portion 121 and the second portion 122. In pixel PX1, the film thickness of the second portion 122 of color filter 120 is formed thinner than the first portion 121. Here, the film thickness of the second portion 122 of the G-color filter 120 in pixel region PR2 is formed thinner than the film thickness of the second portion 122 of the R-color filter 120 in pixel region PR1 and the film thickness of the second portion 122 of the B-color filter 120 in pixel region PR3. Therefore, regarding the film thickness difference between the first portion 121 which is the standard film thickness portion and the second portion 122 which is the thinned film portion, the film thickness difference in the G-color filter 120 is larger than the film thickness difference in the R-color and B-color filters 120. Since the transmittance increases when the film thickness is formed thinner, even if the areas are the same, in pixel PX1, the ratio of the area of the second portion 122 in pixel regions PR1, PR2, and PR3 is the same, but the transmittance of pixel region PR2 is higher than that of pixel regions PR1 and PR3. As described above, since the G color has the property that a change in chromaticity due to a change in film thickness is difficult to be visually recognized, even if the film thickness difference is large compared to other colors, the change in chromaticity is difficult for the user to visually recognize.

[0067] Furthermore, in pixel PX2, the color filter 120 is composed of a first portion 121 having a first transmittance and a second portion 122 having a second transmittance higher than the first transmittance. As shown in FIG. 16(c), in pixel regions PR1, PR2, and PR3 of pixel PX2, compared with pixel PX1, more of the second portion 122 is included. Therefore, when pixel PX2 is viewed in plan view, the ratio of the area of the second portion 122 to the combined area of the first portion 121 and the second portion 122 is higher compared with pixel PX1. For this reason, the color filter 120 of pixel PX2 has a higher transmittance than the color filter 120 of pixel PX1. Here, the ratio of the area occupied by the second portion 122 in each of pixel regions PR1, PR2, and PR3 is the same. FIG. 17(g) is a cross-sectional view taken along line XVIIg-XVIIg of the sub-pixel SPR shown in FIG. 16(c). Further, FIG. 17(h) is a cross-sectional view taken along line XVIIh-XVIIh of the sub-pixel SPG shown in FIG. 16(c). Further, FIG. 17(i) is a cross-sectional view taken along line XVIIi-XVIIi of the sub-pixel SPB shown in FIG. 16(c). As shown in FIGS. 17(g) to (i), the color filters 120 for R, G, and B are composed of the first portion 121 and the second portion 122. Also in pixel PX2, the film thickness of the second portion 122 of the color filter 120 is formed thinner than that of the first portion 121. Also, the film thickness of the second portion 122 of the color filter 120 for G is formed thinner than the film thickness of the second portion 122 of the color filters 120 for the other colors and has a higher transmittance.

[0068] Furthermore, as shown in FIG. 16(d), also in pixel PX3, the color filter 120 is composed of a first portion 121 having a first transmittance and a second portion 122 having a second transmittance higher than the first transmittance. When pixel PX3 is viewed in plan view, the ratio of the area of the second portion 122 to the combined area of the first portion 121 and the second portion 122 is higher than that of pixel PX2 shown in FIG. 16(c). Therefore, the color filter 120 of pixel PX3 has a higher transmittance than the color filter 120 of pixel PX2. Here, the ratio of the area occupied by the second portion 122 in pixel regions PR1, PR2, and PR3 is the same. FIG. 18(j) is a cross-sectional view taken along line XVIIIj-XVIIIj of the sub-pixel SPR shown in FIG. 16(d). FIG. 18(k) is a cross-sectional view taken along line XVIIIk-XVIIIk of the sub-pixel SPG shown in FIG. 16(d). FIG. 18(l) is a cross-sectional view taken along line XVIIIl-XVIIIl of the sub-pixel SPB shown in FIG. 16(d). As shown in FIGS. 18(j) to (l), the color filters of R, G, and B are composed of the first portion 121 and the second portion 122. Also in pixel PX3, the film thickness of the second portion 122 of the color filter 120 is formed thinner than that of the first portion 121. Further, the film thickness of the second portion 122 of the G-color filter 120 is formed thinner than the film thicknesses of the second portions 122 of the color filters 120 of other colors, and has a high transmittance.

[0069] In addition, as shown in FIG. 16(e), in pixel PX4, the color filter 120 is composed only of a second portion 122 having a second transmittance higher than the first transmittance in pixel regions PR1, PR2, and PR3. When pixel PX4 is viewed in plan view, the ratio of the area of the second portion 122 to the combined area of the first portion 121 and the second portion 122 is 1, which is higher than that of pixel PX3 shown in FIG. 16(d). FIG. 18(m) is a cross-sectional view taken along line XVIII m-XVIII m of the sub-pixel SPR shown in FIG. 16(e). FIG. 18(n) is a cross-sectional view taken along line XVIII n-XVIII n of the sub-pixel SPG shown in FIG. 16(e). FIG. 18(o) is a cross-sectional view taken along line XVIII o-XVIII o of the sub-pixel SPB shown in FIG. 16(e). As shown in FIGS. 18(m) to (o), also in pixel PX4, the film thickness of the second portion 122 of the G-color filter 120 is formed thinner than that of the second portion 122 of the color filters 120 of other colors, and the transmittance is high.

[0070] In the present embodiment, in pixels PX to PX4, by increasing in order the ratio of the area of the second portion 122 having a transmittance higher than that of the first portion 121 with respect to the area when the pixel regions PR1, PR2, and PR3 are viewed in plan view, the transmittance can be increased from pixel PX to pixel PX4. Further, in the pixel regions PR1, PR2, and PR3, the film thickness difference between the first portion 121 and the second portion 122 is made different. By providing a second portion with a high transmittance for the R, G, and B color filters, the thickness of the color filter changes, and due to this change in the thickness of the color filter, the chromaticity also changes. This change in chromaticity is preferably within a range that is difficult for the user to visually recognize. Here, G is the least likely to have a change in chromaticity due to a change in film thickness being visually recognized, and next, R has a tendency for a change in chromaticity due to a change in film thickness to be difficult to visually recognize. Therefore, by making the film thickness difference between the first portion 121 and the second portion 122 different for each color of the color filter, the change in chromaticity is difficult to visually recognize, and the required transmittance can be obtained. That is, the film thickness difference between the first portion 121 and the second portion 122 of the G-color filter is made the largest, next, the film thickness difference of the R-color filter is made large, and the film thickness difference of the B-color filter is made the smallest. Thereby, within a range where the change in chromaticity is suppressed and the change in chromaticity is not visually recognized, the transmittance can be increased from pixel PX to pixel PX4. In the above embodiment, the area ratio of the second portion 122 of the filter of each color within the same pixel is made the same, but it may be different, and by combining it with the change in the film thickness difference, the degree of freedom in setting the transmittance increases.

[0071] Although the present disclosure has been described in accordance with each embodiment, the present disclosure is not limited to these. It is obvious to those skilled in the art that various changes, improvements, combinations, etc. are possible.

[0072] Also, in the above-described present embodiment, a configuration including four regions surrounding the central region 110 has been described as an example, but the number of regions surrounding the central region 110 is not limited to four. Such a region may have at least one, and can be any number. The number and position of the regions provided can be changed according to the luminance distribution of the backlight 200.

[0073] In addition, in the above-described embodiments, a configuration in which the backlight is a local dimming backlight has been taken as an example. However, the backlight is not limited to this. The configuration of the present disclosure can be applied to any liquid crystal display device in which there is a region where the in-plane luminance of the backlight is decreased, and as a result, the display region includes a region where the luminance distribution is not uniform.

[0074] In the above-described embodiments, a case where the liquid crystal display panel has color filters of three colors, RGB, has been taken as an example. However, the colors of the color filters are not limited to these. For example, colors other than RGB may be used, or a single color may be used.

Explanation of Reference Numerals

[0075] 10 Liquid crystal display device, 100 Liquid crystal display panel, 101 Display region, 102 Frame region, 103 Active matrix substrate, 104 Counter substrate, 106, 108 Overcoat film, 107 Electrode formation layer, 110 Central region, 111 First region, 112 Second region, 113 Third region, 114 Fourth region, 120, 125 Color filter, 121, 126 First portion, 122, 127 Second portion, 200 Backlight, 200a Emission region, 201 Illumination region, 210 Central illumination region, 211 First illumination region, 212 Second illumination region, 213 Third illumination region, 214 Fourth illumination region, 300 Control unit, BM Black matrix, LC Liquid crystal, PR, PR1, PR2, PR3 Pixel region, PX~PX4 Pixel, SPR, SPG, SPB Sub-pixel

Claims

1. A lighting unit having a first lighting area with a first luminance and a second lighting area with a second luminance lower than the first luminance, A liquid crystal display unit including a first area illuminated by the first lighting area and a second area illuminated by the second lighting area, Pixels provided in the second area of the liquid crystal display unit include a color filter having a first portion with a first transmittance and a second portion with a second transmittance higher than the first transmittance, i) Pixels provided in the first area include a color filter having only the first portion with the first transmittance, or ii) Pixels provided in the first area include a color filter having the first portion with the first transmittance and the second portion with the second transmittance, and in the pixels provided in the second area of the liquid crystal display unit, the ratio of the second portion to the first portion and the second portion is higher than the ratio of the second portion to the first portion and the second portion in the pixels provided in the first area, A liquid crystal display device.

2. The thickness of the second portion is thinner than that of the first portion, The liquid crystal display device according to Claim 1.

3. The second portion and the first portion of the color filter are formed of different materials, The liquid crystal display device according to Claim 1.

4. The first portion and the second portion are arranged side by side in a stripe shape when the pixel is viewed in plan view, The liquid crystal display device according to Claim 1.

5. The pixel is divided into a plurality of domains, In each of the plurality of domains, the ratio of the second portion to the first portion and the second portion is the same, The liquid crystal display device according to Claim 1.

6. The cell gap of the area where the second portion is provided is larger than the cell gap of the area where the first portion is provided, The liquid crystal display device according to Claim 2.

7. The lighting unit is a local dimming backlight, The second lighting area is provided so as to surround the first lighting area, The second area is provided so as to surround the first area, The liquid crystal display device according to Claim 1.

8. The color filter includes color filters of three colors, R, G, and B, The second portion is provided in at least one color filter of R, G, and B, The liquid crystal display device according to Claim 1.

9. The color filter includes color filters of three colors, R, G, and B, the second portion is provided in at least two color filters of R, G, and B, and the ratio occupied by the second portion with respect to the first portion and the second portion varies for each color. The liquid crystal display device according to claim 1.

10. The color filter includes color filters of three colors, R, G, and B, the second portion is provided in at least two color filters of R, G, and B, and the film thickness difference between the second portion and the first portion varies for each color. The liquid crystal display device according to claim 1.

Images