Liquid crystal display device

Abstract

To provide a liquid crystal display device that can perform partial driving with a simple structure.SOLUTION: A liquid crystal display device 10 includes a liquid crystal display panel 20, a backlight 30 disposed on a rear surface of the liquid crystal display panel 20, and a light diffusion element 40 disposed between the liquid crystal display panel 20 and the backlight 30. The backlight 30 emits collimated light 31. The light diffusion element 40 is divided into a plurality of segments. For each segment, a transmission state 41 in which the collimated light 31 from the backlight 30 is transmitted and emitted and an emission state 42 in which the collimated light 31 from the backlight 30 is diffused and emitted can be independently switched.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a liquid crystal display device. [Background technology]

[0002] In order to improve image quality, a liquid crystal display device may perform local dimming, in which the backlight is divided into a plurality of segments and partially illuminated.

[0003] For example, Figures 3 and 8 to 10 of Patent Document 1 describe a technology in which one LED (60) is arranged in each segment (141) that performs local dimming, and each segment (141) is separated by a partition plate (70). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-74264 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the technique described in Patent Document 1 has a problem in that as the number of segments increases, the number of LEDs also increases, resulting in higher costs.

[0006] An object of the present invention is to provide a liquid crystal display device that can perform partial driving with a simple configuration. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, the liquid crystal display device of the present invention comprises a liquid crystal display panel, a backlight arranged on the back of the liquid crystal display panel, and a light diffusion element arranged between the liquid crystal display panel and the backlight, wherein the backlight emits collimated light, and the light diffusion element is divided into a plurality of segments, and each of the plurality of segments can be independently switched between a transmission state in which the collimated light from the backlight is transmitted and emitted, and a diffusion state in which the collimated light from the backlight is diffused and emitted. [Effects of the Invention]

[0008] According to the present invention, it is possible to realize a liquid crystal display device that can perform partial driving with a simple configuration. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a top view of the light diffusing element according to the first embodiment. [Figure 2] FIG. 1 is a cross-sectional view of a liquid crystal display device according to a first embodiment. [Figure 3] FIG. 2 is a cross-sectional view of the light diffusing element of the first embodiment. [Figure 4] FIG. 2 is a plan view of a first substrate in the light diffusing element of the first embodiment. [Figure 5] FIG. 3 is a cross-sectional view illustrating the operation of the light diffusing element of the first embodiment due to an electric field on the first substrate side. [Figure 6] FIG. 3 is a plan view of a second substrate in the light diffusing element of the first embodiment. [Figure 7] FIG. 3 is a cross-sectional view illustrating the operation of the light diffusing element of the first embodiment due to an electric field on the second substrate side. [Figure 8] FIG. 10 is a cross-sectional view of a light diffusing element according to a second embodiment. [Figure 9] FIG. 10 is a plan view of a second substrate in the light diffusing element of Example 2. [Figure 10] FIG. 10 is a perspective view of a backlight according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each drawing and embodiment, the same or similar components are designated by the same reference numerals, and redundant explanations will be omitted. [Example]

[0011] Fig. 1 is a top view of a light diffusing element of Example 1. Fig. 2 is a cross-sectional view of a liquid crystal display device of Example 1. The position of the cross section in Fig. 2 corresponds to the position AA in Fig. 1.

[0012] 2, the liquid crystal display device 10 of this embodiment includes a liquid crystal display panel 20, a backlight 30 disposed on the rear surface of the liquid crystal display panel 20, and a light diffusing element 40 disposed between the liquid crystal display panel 20 and the backlight 30. The liquid crystal display device 10 also includes, for example, an optical sheet, a control device, a housing, and the like, which are not shown in the drawings.

[0013] The liquid crystal display panel 20 has, for example, an upper substrate, a lower substrate, a liquid crystal layer sandwiched between the upper and lower substrates, electrodes for driving the liquid crystal layer, an upper polarizer arranged above the upper substrate, and a lower polarizer arranged below the lower substrate.

[0014] The backlight 30 is a surface-emitting lighting device. The backlight 30 of this embodiment emits collimated light 31.

[0015] 1 and 2, the light diffusing element 40 is divided into a plurality of segments. In this embodiment, an example will be described in which the light diffusing element 40 is divided into four segments (A11, A12, A21, and A22), two segments in the vertical direction and two segments in the horizontal direction. Note that the segment division method and the number of divisions are merely examples and are not limited to these.

[0016] The light diffusion element 40 of this embodiment can independently switch between a transmission state 41 in which collimated light 31 from the backlight 30 is transmitted and emitted, and a diffusion state 42 in which collimated light 31 from the backlight 30 is diffused and emitted, for each of the multiple segments.

[0017] For example, the segment A11 is in the transmissive state 41, and transmits the collimated light 31 from the backlight 30 and emits it as transmitted light 41A. Therefore, the transmitted light 41A remains collimated light.

[0018] In contrast, segment A12 is in a diffusion state 42, diffusing collimated light 31 from backlight 30 and emitting it as diffused light 42A. Diffused light 42A has a lower front luminance than transmitted light 41A, so segment A12 is darker than segment A11. FIG. 1 shows an example in which segments A21 and A22 are also in the diffusion state 42, just like segment A12.

[0019] As described above, by combining a backlight 30 that emits collimated light 31 with a light diffusion element 40, and using the light diffusion element 40 to independently switch between a transmission state 41 and a diffusion state 42 for each segment, partial driving can be performed, in which the light from the backlight 30 is divided into multiple segments and partially illuminated.

[0020] FIG. 3 is a cross-sectional view of the light diffusing element of the first embodiment.

[0021] The light diffusing element 40 of this embodiment has a first substrate 43, a second substrate 44, a liquid crystal layer 45 disposed between the first substrate 43 and the second substrate 44, and a plurality of electrodes 46, and is capable of switching between a transmissive state 41 and a diffusing state 42 by applying a predetermined voltage to each of the plurality of electrodes 46. The plurality of electrodes 46 are preferably made of transparent electrodes so as to block as little of the collimated light 31 as possible. Note that the number and size of the plurality of electrodes 46 are exaggerated for clarity in the drawings, and therefore it is desirable that they be smaller and that a greater number of them be disposed in practice.

[0022] FIG. 4 is a plan view of the first substrate in the light diffusing element of the first embodiment.

[0023] The plurality of electrodes 46 include a first common electrode 46A formed on the first substrate 43 and extending in a first direction (the vertical direction in the figure in this embodiment), and first drive electrodes 46B formed on the first substrate 43 and extending in the first direction. Here, a voltage is applied to the first drive electrodes 46B independently for each segment.

[0024] 4 does not show the lead-out wiring and terminals for applying predetermined voltages to the first common electrode 46A and the first drive electrode 46B, and only the electrical connection relationship using the lead-out wiring is shown with lines. For example, the first common electrode 46A is connected in common to four segments (A11, A12, A21, and A22), and a voltage E1 is applied to it. In contrast, a voltage E2 is applied to the first drive electrode 46B in segment A11, a voltage E3 is applied to segment A12, a voltage E4 is applied to segment A21, and a voltage E5 is applied to segment A22.

[0025] 5 is a cross-sectional view illustrating the operation of the light diffusing element due to the electric field on the first substrate side in Example 1. FIG 5 is a partial cross-sectional view seen from below in FIG 4.

[0026] In the absence of an electric field 47, the liquid crystal molecules in the liquid crystal layer 45 are oriented with their longitudinal direction aligned with the major surface of the first substrate 43. As shown in FIG. 5, a voltage equal to or greater than a predetermined threshold is applied between the first common electrode 46A and the first drive electrode 46B to generate an electric field 47, thereby driving the liquid crystal layer 45 and controlling the orientation of the liquid crystal molecules to follow the electric field 47. This allows the liquid crystal layer 45 to enter the diffusion state 42. Furthermore, by setting the voltage between the first common electrode 46A and the first drive electrode 46B to zero or a value smaller than a predetermined value, the electric field 47 is eliminated or weakened, allowing the liquid crystal layer 45 to enter the transmissive state 41.

[0027] FIG. 6 is a plan view of the second substrate in the light diffusing element of the first embodiment.

[0028] The second substrate 44 has a configuration similar to that of the first substrate 43, but the extending direction of the electrodes 46 is different. The multiple electrodes 46 include a second common electrode 46C formed on the second substrate 44 and extending in a second direction (the horizontal direction in the figure in this embodiment) different from the first direction, and a second drive electrode 46D formed on the second substrate 44 and extending in the second direction. Here, a voltage is applied to each segment of the second drive electrode 46D independently.

[0029] 6, as in FIG. 4, the drawing wiring and terminals are omitted, and only the electrical connection relationships using the drawing wiring are shown with lines. The second common electrode 46C is connected in common to four segments (A11, A12, A21, and A22), and a voltage E6 is applied to it. It is desirable that the voltage E6 be the same as the voltage E1. In contrast, the second drive electrode 46D is applied with a voltage E7 to segment A11, a voltage E8 to segment A12, a voltage E9 to segment A21, and a voltage E10 to segment A22.

[0030] 7 is a cross-sectional view illustrating the operation of the light diffusing element due to the electric field on the second substrate side in Example 1. FIG. 7 is a partial cross-sectional view seen from the lateral direction of FIG.

[0031] The operation in Figure 7 is almost the same as the operation described in Figure 5, except that the first common electrode 46A is replaced by the second common electrode 46C, and the first drive electrode 46B is replaced by the second drive electrode 46D, so a detailed description will be omitted.

[0032] In this embodiment, the liquid crystal layer 45 is driven on both the first substrate 43 and the second substrate 44, which makes it possible to strengthen the diffusion in the diffusion state 42. Furthermore, the plurality of electrodes 46 extend in the first direction on the first substrate 43, and the plurality of electrodes 46 extend in the second direction on the second substrate 44, which makes it possible to make the diffusion direction uniform.

[0033] As described above, according to this embodiment, unlike the method of performing partial driving by individually driving the LEDs that are the light sources, there is no need to increase the number of LEDs for partial driving even if the number of segments increases, so partial driving can be performed with a simple configuration. [Example]

[0034] Fig. 8 is a cross-sectional view of the light diffusing element of Example 2. Fig. 9 is a plan view of the second substrate in the light diffusing element of Example 2.

[0035] Example 2 is a modification of Example 1, in which the second substrate 44 side is provided with a solid common electrode. In this example, the multiple electrodes 46 include a second common electrode 46C formed on the second substrate 44 and covering the entire surfaces of the multiple segments. A voltage E6 is applied to the second common electrode 46C. It is desirable that the voltage E6 be the same as the voltage E1.

[0036] According to this embodiment, partial driving can be performed with an even simpler configuration than in the first embodiment. [Example]

[0037] FIG. 10 is a perspective view of a backlight according to a third embodiment.

[0038] The third embodiment is an embodiment that explains an example of the structure of the backlight 30 explained in the first embodiment.

[0039] The backlight 30 of this embodiment is a side light type backlight, as shown in Fig. 10. The backlight 30 emits collimated light 31. The backlight 30 includes a reflective sheet 32, a light guide plate 33, and a prism sheet 34, which are stacked in the Z direction. The light source 35 is disposed on a light source substrate 36 along the Y direction. The light source substrate 36 on which the light source 35 is mounted is disposed opposite a side surface of the light guide plate 33. Light emitted from the light source 35 in the X direction enters the light guide plate 33 from the side surface of the light guide plate 33 and is emitted from the surface of the light guide plate 33 facing the prism sheet 34.

[0040] According to this embodiment, by using a side light type backlight, a thin backlight 30 can be obtained, and by combining it with the light diffusing element 40, partial driving becomes possible.

[0041] Although the embodiments of the present invention have been described above, the present invention is not limited to the configurations described in the embodiments, and various modifications are possible within the scope of the technical concept of the present invention. In addition, some or all of the configurations described in the embodiments may be combined and applied. [Explanation of symbols]

[0042] 10:LCD display device 20: LCD display panel 30: Backlight 31: Collimated light 32: Reflective sheet 33: Light guide plate 34: Prism sheet 35: Light source 36: Light source board 40: Light diffusion element 41:Transparent state 41A: Transmitted light 42: Diffusion state 42A: Diffused light 43: First substrate 44: Second board 45: Liquid crystal layer 46: Electrode 46A: First common electrode 46B: First drive electrode 46C: Second common electrode 46D: Second drive electrode 47: Electric field A11, A12, A21, A22: Segments E1~E10: Voltage

Claims

1. A liquid crystal display panel; a backlight disposed on the rear surface of the liquid crystal display panel; a light diffusing element disposed between the liquid crystal display panel and the backlight; the backlight emits collimated light; The liquid crystal display device is characterized in that the light diffusion element is divided into a plurality of segments, and each of the plurality of segments can be independently switched between a transmission state in which the collimated light from the backlight is transmitted and emitted, and a diffusion state in which the collimated light from the backlight is diffused and emitted.

2. In claim 1, The liquid crystal display device is characterized in that the light diffusion element has a first substrate, a second substrate, a liquid crystal layer arranged between the first substrate and the second substrate, and a plurality of electrodes, and is capable of switching between the transmissive state and the diffusing state by applying a predetermined voltage to each of the plurality of electrodes.

3. In claim 2, the plurality of electrodes include a first common electrode formed on the first substrate and extending in a first direction, and a first drive electrode formed on the first substrate and extending in the first direction; A liquid crystal display device, characterized in that a voltage is applied to the first drive electrodes independently for each of the segments.

4. In claim 3, the plurality of electrodes include a second common electrode formed on the second substrate and extending in a second direction different from the first direction, and a second drive electrode formed on the second substrate and extending in the second direction; A liquid crystal display device, characterized in that a voltage is applied to the second drive electrodes independently for each of the segments.

5. In claim 3, The liquid crystal display device according to claim 1, wherein the plurality of electrodes includes a second common electrode formed on the second substrate and covering the entire surfaces of the plurality of segments.

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