Liquid crystal display device

Abstract

To improve the display quality of a translucent liquid crystal display device which comes with a circular polarizing plate, and in which a liquid crystal layer takes monodomain orientation.SOLUTION: A pixel electrode of the liquid crystal display device includes at least one unit pixel electrode in which a liquid crystal domain is formed above each of these, with each pixel including a unit pixel corresponding to the unit pixel electrode. The unit pixel includes a reference region and a transmission region which is smaller than the reflection region. The outer edge of the unit pixel electrode includes a first and a second electrode side. A direction orthogonal to the first electrode side and leading toward the inside of the unit pixel electrode forms an angle of over 90° with a reference orientation direction, and a direction orthogonal to the second electrode side and leading toward the inside of the unit pixel electrode forms an angle of less than 90° with the reference orientation direction. The liquid crystal layer is of a negative type, and the distance from the second electrode side to the transmission region is smaller than the distance from the first electrode side to the transmission region. Or, the liquid crystal layer is of a positive type, and the distance from the first electrode side to the transmission region is smaller than the distance from the second electrode side to the transmission region.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a liquid crystal display device, and more particularly to a transflective liquid crystal display device in which each pixel includes a reflective region and a transmissive region.

Background Art

[0002] In recent years, a transflective (sometimes called "transmissive-reflective dual-mode") liquid crystal display device (LCD) has been used as a display device for smartwatches and digital signage for outdoor advertising. The transflective LCD has, within one pixel, a reflective region for performing display in a reflective mode (reflective display) and a transmissive region for performing display in a transmissive mode (transmissive display). Therefore, high visibility in an outdoor environment under sunlight can be obtained by reflective display using external light, and information can be confirmed at night by transmissive display using a backlight. The transflective LCD is disclosed, for example, in Patent Document 1.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As a result of intensive studies on the transflective LCD, the inventor of the present application has found that in a transflective LCD provided with a circular polarizing plate as a polarizing plate and in which the liquid crystal layer has a monodomain alignment, flicker that is observed only from an oblique direction occurs during transmissive display. This flicker was not observed from the front direction.

[0005] In recent years, since the requirements for display quality have been increasing, suppression of the above-described flicker is desired. Further, when low-frequency driving (for example, 0.5 Hz driving or the like) is performed for power consumption reduction, flicker is likely to be observed. Therefore, from the viewpoint of performing low-frequency driving, it is preferable that the above-described flicker is suppressed.

[0006] An embodiment of the present invention has been made in view of the above problems, and an object thereof is to improve the display quality of a transflective liquid crystal display device including a circular polarizing plate and in which a liquid crystal layer has a monodomain alignment.

Means for Solving the Problems

[0007] This specification discloses a liquid crystal display device described in the following items.

[0008] [Item 1] A first substrate, A second substrate facing the first substrate, A liquid crystal layer provided between the first substrate and the second substrate, At least a pair of circular polarizing plates facing each other through at least the liquid crystal layer, Comprising, A liquid crystal display device having a plurality of pixels arranged in a matrix, The first substrate has pixel electrodes provided for each of the plurality of pixels, When a voltage is applied to the liquid crystal layer, the liquid crystal layer has a monodomain alignment in which at least one type of liquid crystal domain is formed in each of the plurality of pixels, Each of the pixel electrodes includes at least one unit pixel electrode on which the liquid crystal domain is formed, Each of the plurality of pixels includes at least one unit pixel which is a region corresponding to the at least one unit pixel electrode, The unit pixel includes a reflection region for performing display in a reflection mode and a transmission region for performing display in a transmission mode, and the transmission region has an area smaller than the area of the reflection region in a plan view. The outer edge of the unit pixel electrode includes at least one first electrode side and at least one second electrode side. When the direction of the director of the liquid crystal domain is called the reference alignment direction, the direction perpendicular to the first electrode side and toward the inside of the unit pixel electrode forms an angle greater than 90° with the reference alignment direction. the direction perpendicular to the second electrode side and toward the inside of the unit pixel electrode forms an angle less than 90° with the reference alignment direction. The liquid crystal layer is formed of a negative liquid crystal material, and in the unit pixel, the distance from the second electrode side to the transmission region is smaller than the distance from the first electrode side to the transmission region, or the liquid crystal layer is formed of a positive liquid crystal material, and in the unit pixel, the distance from the first electrode side to the transmission region is smaller than the distance from the second electrode side to the transmission region. A liquid crystal display device.

[0009] [Item 2] a first substrate, a second substrate facing the first substrate, a liquid crystal layer provided between the first substrate and the second substrate, a pair of circular polarizing plates facing each other through at least the liquid crystal layer, and comprising a liquid crystal display device having a plurality of pixels arranged in a matrix, the first substrate has pixel electrodes provided for each of the plurality of pixels, when a voltage is applied to the liquid crystal layer, the liquid crystal layer takes a monodomain alignment in which at least one type of liquid crystal domain is formed in each of the plurality of pixels, each of the pixel electrodes includes at least one unit pixel electrode on which the liquid crystal domain is formed, each of the plurality of pixels includes at least one unit pixel which is a region corresponding to the at least one unit pixel electrode, The unit pixel includes a reflective region that performs display in a reflective mode and a transmissive region that performs display in a transmissive mode, the transmissive region having an area smaller than the area of the reflective region in a plan view. When the direction of the director of the liquid crystal domain is referred to as the reference alignment direction, the liquid crystal layer is formed of a negative liquid crystal material, and in the unit pixel, the transmissive region is displaced to the side opposite to the reference alignment direction with respect to the center of the unit pixel, or the liquid crystal layer is formed of a positive liquid crystal material, and in the unit pixel, the transmissive region is displaced to the reference alignment direction side with respect to the center of the unit pixel. A liquid crystal display device.

[0010] [Item 3] The liquid crystal display device according to item 1 or 2, which can be driven at a driving frequency of 30 Hz or less.

[0011] [Item 4] In each of the plurality of pixels, the thickness of the liquid crystal layer in the reflective region and the thickness of the liquid crystal layer in the transmissive region are substantially the same. The liquid crystal display device according to any one of items 1 to 3.

[0012] [Item 5] The liquid crystal layer does not take a twisted alignment, In each of the plurality of pixels, the thickness of the liquid crystal layer in the transmissive region is larger than the thickness of the liquid crystal layer in the reflective region. The liquid crystal display device according to any one of items 1 to 3.

[0013] [Item 6] The plurality of pixels include a red pixel that displays red, a green pixel that displays green, and a blue pixel that displays blue, The thickness of the liquid crystal layer in at least one of the red pixel, the green pixel, and the blue pixel is different from the thickness of the liquid crystal layer in at least one of the others. The liquid crystal display device according to item 5.

[0014] [Item 7] The liquid crystal display device according to any one of items 1 to 6, further comprising a memory circuit connected to each of the plurality of pixels.

[0015] [Item 8] In each of the at least one unit pixel, The liquid crystal display device according to any one of items 1 to 7, wherein the transmissive region has a shape substantially similar to the shape of the unit pixel in plan view. [Advantages of the Invention]

[0016] According to an embodiment of the present invention, it is possible to improve the display quality of a transflective liquid crystal display device including a circular polarizing plate and having a monodomain alignment of a liquid crystal layer. [Brief Description of the Drawings]

[0017]

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Mode for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the following embodiments.

[0019] [Embodiment 1] With reference to FIGS. 1 and 2, the liquid crystal display device 100 in the present embodiment will be described. The liquid crystal display device 100 of the present embodiment is a transflective liquid crystal display device. FIG. 1 is a cross-sectional view schematically showing the liquid crystal display device 100. FIG. 2 is a plan view showing a region corresponding to one pixel P of the liquid crystal display device 100.

[0020] As shown in FIG. 1, the liquid crystal display device 100 includes a TFT substrate (first substrate) 10, a counter substrate (second substrate) 20 facing the TFT substrate 10, and a liquid crystal layer 30 provided between the TFT substrate 10 and the counter substrate 20. The TFT substrate 10 is located on the back side of the liquid crystal layer 30 (i.e., the side opposite to the observer), and the counter substrate 20 is located on the front side of the liquid crystal layer 30 (i.e., the observer side).

[0021] Further, the liquid crystal display device 100 includes a pair of circular polarizing plates 40A and 40B. The pair of circular polarizing plates 40A and 40B face each other at least through the liquid crystal layer 30. In the illustrated example, one of the pair of circular polarizing plates 40A and 40B (hereinafter referred to as the "back circular polarizing plate") 40A is disposed on the back side of the TFT substrate 10, and the other (hereinafter referred to as the "front circular polarizing plate") 40B is disposed on the front side of the counter substrate 20. Each of the back circular polarizing plate 40A and the front circular polarizing plate 40B can be a circular polarizing plate of various known types. For example, the back circular polarizing plate 40A can be a combination of a linear polarizing plate and a retardation plate located between the linear polarizing plate and the TFT substrate 10. Also, for example, the front circular polarizing plate 40B can be a combination of a linear polarizing plate and a retardation plate located between the linear polarizing plate and the counter substrate 20.

[0022] The liquid crystal display device 100 further includes an illumination device (backlight) 50. The illumination device 50 is disposed on the back side of the back circular polarizing plate 40A. In the illustrated example, the illumination device 50 includes a light source (e.g., LED) 51 that emits light, a light guide plate 52 that guides the light from the light source 51 toward the back circular polarizing plate 40A side, and a reflector 53 disposed on the back side of the light guide plate 52. The illumination device 50 may further include a prism sheet and a diffusion sheet disposed on the front side (or back side) of the light guide plate 52.

[0023] The liquid crystal display device 100 has a plurality of pixels P arranged in a matrix. The plurality of pixels P typically include a red pixel for displaying red, a green pixel for displaying green, and a blue pixel for displaying blue. FIG. 2 shows one pixel P among the plurality of pixels P of the liquid crystal display device 100. The TFT substrate 10 has a pixel electrode 11 provided for each pixel P.

[0024] When a voltage is applied to the liquid crystal layer 30, the liquid crystal layer 30 takes a monodomain alignment. That is, when a voltage is applied to the liquid crystal layer 30, at least one liquid crystal domain of one type is formed in each pixel P. Here, three liquid crystal domains of one type are formed in each pixel P. FIG. 2 shows the direction of the director (hereinafter sometimes referred to as the "reference alignment direction") RD of each liquid crystal domain. The direction RD of the director is the tilt direction of the liquid crystal molecules near the center in the thickness direction of the liquid crystal layer 30 when a voltage is applied. The tilt direction here is the azimuthal direction. The reference of the azimuthal direction is the horizontal direction of the display surface, and the counterclockwise direction is positive (taking the display surface as an example of a clock face, the 3 o'clock direction is the azimuth angle 0°, and the counterclockwise direction is positive).

[0025] Each pixel electrode 11 includes at least one unit pixel electrode 11a on which a liquid crystal domain is formed. Here, the pixel electrode 11 includes three unit pixel electrodes 11a. When the pixel electrode 11 includes a plurality of unit pixel electrodes 11a, each unit pixel electrode 11a may also be referred to as a "sub-pixel electrode".

[0026] Each pixel P includes at least one unit pixel Up which is a region corresponding to at least one unit pixel electrode 11a. Here, each pixel P includes three unit pixels Up. When the pixel P includes a plurality of unit pixels Up, each unit pixel Up may also be referred to as a "sub-pixel".

[0027] The unit pixel Up includes a reflective region Rf for performing display in a reflective mode and a transmissive region Tr for performing display in a transmissive mode. The transmissive region Tr has an area smaller than the area of the reflective region Rf in a plan view. The ratio of the area of the transmissive region Tr occupying within the pixel P is appropriately set according to applications and the like, and is not particularly limited. For example, it is 10% or more and less than 50%.

[0028] Here, with further reference to FIGS. 3, 4A, and 4B, the configuration of the liquid crystal display device 100 will be described in more detail. FIG. 3 is a plan view showing regions corresponding to three pixels P (red pixel P R , green pixel P G and blue pixel P B ) of the liquid crystal display device 100. FIGS. 4A and 4B are cross-sectional views taken along lines 4A-4A' and 4B-4B' in FIG. 3, respectively.

[0029] The TFT substrate 10 has a pixel electrode 11 provided for each of a plurality of pixels P and a reflective layer 12 located on the side opposite to the liquid crystal layer 30 with respect to the pixel electrode 11 (that is, on the back side of the pixel electrode 11). The TFT substrate 10 further has a first interlayer insulating layer 13, a second interlayer insulating layer 14, a contact portion CP, and a first alignment film 15.

[0030] The components of the TFT substrate 10 (such as the pixel electrode 11 described above) are supported by the substrate 10a. The substrate 10a is, for example, a glass substrate or a plastic substrate.

[0031] On the substrate 10a, a circuit (backplane circuit) for driving the pixel P is formed (not shown). Here, the backplane circuit has a memory circuit (for example, SRAM) connected to each of a plurality of pixels P. A liquid crystal display device provided with a memory circuit for each pixel P is sometimes called a "memory liquid crystal". The specific configuration of the memory liquid crystal is disclosed, for example, in Japanese Patent No. 5036864 (corresponding to U.S. Patent No. 8692758). All the disclosure contents of Japanese Patent No. 5036864 and U.S. Patent No. 8692758 are incorporated herein by reference for reference purposes.

[0032] The first interlayer insulating layer 13 is provided so as to cover the backplane circuit. The surface of the first interlayer insulating layer 13 has an uneven shape. That is, the first interlayer insulating layer 13 has an uneven surface structure. The first interlayer insulating layer 13 having the uneven surface structure can be formed using a photosensitive resin as described in, for example, Japanese Patent No. 3394926.

[0033] The reflective layer 12 is provided on the first interlayer insulating layer 13. The reflective layer 12 is formed of a metal material having a high reflectance. Here, a silver alloy is used as the metal material for forming the reflective layer 12, but it is not limited thereto, and for example, aluminum or an aluminum alloy may be used. The surface of the reflective layer 12 has an uneven shape that reflects the uneven surface structure of the first interlayer insulating layer 13. That is, the reflective layer 12 also has an uneven surface structure. The uneven surface structure of the reflective layer 12 is provided to diffusely reflect ambient light and realize a display close to paper white. The uneven surface structure can be composed of a plurality of convex portions p randomly arranged such that the center-to-center distance between adjacent convex portions p is 5 μm or more and 50 μm or less, preferably 10 μm or more and 20 μm or less. When viewed from the normal direction of the substrate 10a, the shape of the convex portion p is substantially circular or substantially polygonal. The area of the convex portion p occupying the pixel P is, for example, about 20% to 40%. The height of the convex portion p is, for example, 1 μm or more and 5 μm or less.

[0034] The reflective layer 12 includes a first region 12a located within each of the plurality of pixels P and a second region 12b located between any two adjacent pixels P. The uneven surface structure of the reflective layer 12 is formed in each of the first region 12a and the second region 12b. That is, not only the first region 12a but also the second region 12b has an uneven surface structure. Further, the reflective layer 12 of the TFT substrate 10 has an opening 12o formed in the transmission region Tr.

[0035] The second interlayer insulating layer 14 is a transparent insulating layer provided so as to cover the reflective layer 12.

[0036] The pixel electrode 11 is provided on the second interlayer insulating layer 14. That is, the pixel electrode 11 is disposed on the reflective layer 12 via the transparent insulating layer 14. The pixel electrode 11 is formed of a transparent conductive material. As the transparent conductive material, for example, indium tin oxide (ITO), indium zinc oxide (IZO (registered trademark)), or a mixture thereof can be used. The pixel electrode 11 is electrically connected to a backplane circuit including a memory circuit. A part of the pixel electrode 11 is located within the transmission region Tr, and another part of the pixel electrode 11 is located within the reflection region Rf.

[0037] The contact portion CP electrically connects the pixel electrode 11 and the backplane circuit at the first contact hole CH1 formed in the first interlayer insulating layer 13 and the second contact hole CH2 formed in the second interlayer insulating layer 14. In the illustrated example, the contact portion CP is composed of a first contact electrode 16, a second contact electrode 17, and a third contact electrode 18.

[0038] The first contact electrode 16 is an electrode (or a part of a wiring) exposed within the first contact hole CH1. The second contact electrode 17 is formed on the first interlayer insulating layer 13 and within the first contact hole CH1, and is connected to the first contact electrode 16 within the first contact hole CH1. Also, a part of the second contact electrode 17 is exposed within the second contact hole CH2. The third contact electrode 18 is connected to the second contact electrode 17 and the pixel electrode 11 within the second contact hole CH2. In other words, the third contact electrode 18 is interposed between the second contact electrode 17 and the pixel electrode 11. In the illustrated example, a conductive layer 19 formed from the same conductive film as the second contact electrode 17 (that is, in the same layer as the second contact electrode 17) is interposed between the reflective layer 12 and the first interlayer insulating layer 13. Also, the third contact electrode 18 is formed from the same metal film as the reflective layer 12 (that is, in the same layer as the reflective layer 12). The conductive layer 19 and the third contact electrode 18 may be omitted.

[0039] The counter substrate 20 has a counter electrode (common electrode) 21 and a second alignment film 25. Further, the counter substrate 20 further has a color filter layer and a plurality of columnar spacers (both not shown). The components of the counter substrate 20 (such as the counter electrode 21 described above) are supported by the substrate 20a. The substrate 20a is, for example, a glass substrate or a plastic substrate. Note that the counter substrate 20 does not have a black matrix (light-shielding layer) between any two adjacent pixels P.

[0040] The counter electrode 21 is provided so as to face the pixel electrode 11 and the reflective electrode 12. The counter electrode 21 is formed of a transparent conductive material. As the transparent conductive material for forming the counter electrode 21, the same material as that of the pixel electrode 11 can be used.

[0041] The color filter layer typically includes a red color filter provided in a region corresponding to the red pixel P R a green color filter provided in a region corresponding to the green pixel P G and a blue color filter provided in a region corresponding to the blue pixel P. B The red color filter, the green color filter, and the blue color filter transmit red light, green light, and blue light, respectively.

[0042] The columnar spacers define the thickness (cell gap) of the liquid crystal layer 30. The columnar spacers can be formed of a photosensitive resin.

[0043] The liquid crystal layer 30 is formed of a negative-type (that is, the dielectric anisotropy is negative) liquid crystal material. Here, a chiral agent is added to the liquid crystal material. The liquid crystal layer 30 can be formed, for example, by a droplet discharge method.

[0044] The first alignment film 15 and the second alignment film 25 are each provided so as to be in contact with the liquid crystal layer 30. Here, each of the first alignment film 15 and the second alignment film 25 is a vertical alignment film. At least one of the first alignment film 15 and the second alignment film 25 is subjected to an alignment treatment (for example, rubbing treatment) to define a pretilt direction. The liquid crystal molecules 31 of the liquid crystal layer 30 are vertically aligned in a state where no voltage is applied to the liquid crystal layer 30 (see FIG. 4A), and when a predetermined voltage is applied to the liquid crystal layer 30, they fall and twist. Thus, the liquid crystal layer 30 is a vertically aligned liquid crystal layer.

[0045] In the illustrated example, the thickness (cell gap) dt of the liquid crystal layer 30 in the transmission region Tr and the thickness (cell gap) dr of the liquid crystal layer 30 in the reflection region Rf are substantially the same.

[0046] The liquid crystal display device 100 has a configuration for performing gradation display using memory liquid crystal. Specifically, each pixel P of the liquid crystal display device 100 is divided into a plurality of unit pixels (sub-pixels) Up as shown in FIGS. 2 and 3. Here, one pixel P is divided into three unit pixels Up, and the pixel electrode 11 is divided into three unit pixel electrodes (sub-pixel electrodes) 11a. Among the three unit pixel electrodes 11a, the two unit pixel electrodes 11a arranged on the upper and lower sides in the figure are electrically connected to a common one memory circuit, and the one unit pixel electrode 11a arranged in the center in the figure is electrically connected to another one memory circuit. That is, two memory circuits are provided for each pixel P.

[0047] As shown in FIGS. 2 and 3, since the pixel P is divided, as shown in FIG. 5, four - tone display by the area - gradation method can be performed. Specifically, as shown on the far left of FIG. 5, by setting all three unit pixels Up to the black - display state, the entire pixel P can be black - displayed. As shown second from the left in FIG. 5, by setting two unit pixels Up to the black - display state and one unit pixel Up to the white - display state, the entire pixel P can be displayed in a dark intermediate tone. Also, as shown third from the left in FIG. 5, by setting two unit pixels Up to the white - display state and one unit pixel Up to the black - display state, the entire pixel P can be displayed in a bright intermediate tone. As shown on the far right of FIG. 5, by setting all three unit pixels Up to the white - display state, the entire pixel P can be white - displayed.

[0048] Note that the three unit - pixel electrodes 11a may be electrically connected to different memory circuits respectively (that is, three memory circuits may be provided for each pixel P).

[0049] Subsequently, with reference to FIGS. 6 and 7, the relationship between the direction of the director of the liquid - crystal domain (reference - alignment direction) RD and the arrangement of the transmission region Tr in the unit pixel Up will be described.

[0050] FIG. 6 shows the pre - tilt orientation PD1 defined by the first alignment film 15 of the TFT substrate 10, the pre - tilt orientation PD2 defined by the second alignment film 25 of the counter substrate 20, and the direction of the director of the liquid - crystal domain (reference - alignment direction) RD. Here, the pre - tilt orientation PD1 by the first alignment film 15 is in the 65° direction, the pre - tilt orientation PD2 by the second alignment film 25 is in the 165.5° direction, and the reference - alignment direction RD is in the 25.25° direction.

[0051] FIG. 7 is a diagram for explaining the arrangement of the transmissive region Tr in the unit pixel Up. In the liquid crystal display device 100 of the present embodiment, as shown in FIG. 7, in the unit pixel Up, the transmissive region Tr is arranged so as to be shifted to the side opposite to the reference alignment direction RD with respect to the center cp of the unit pixel Up. Thereby, flicker when observing the transmissive display from an oblique direction is suppressed. The reason for this will be explained below.

[0052] As shown in FIG. 7, the outer edge of the unit pixel electrode 11a includes four electrode sides SD1, SD2, SD3, and SD4. In FIG. 7, directions e1, e2, e3, and e4 that are orthogonal to the respective electrode sides SD1, SD2, SD3, and SD4 and face the inside of the unit pixel electrode 11a are shown. In the present specification, the electrode sides SD1 to SD4 are classified into two types of electrode sides, "first electrode sides" and "second electrode sides", according to the magnitude of the angle formed by these directions e1 to e4 and the reference alignment direction RD. That is, it can be said that the outer edge of the unit pixel electrode 11a includes at least one "first electrode side" and at least one "second electrode side".

[0053] The direction orthogonal to the "first electrode side" and facing the inside of the unit pixel electrode 11a forms an angle of more than 90° with the reference alignment direction RD. On the other hand, the direction orthogonal to the "second electrode side" and facing the inside of the unit pixel electrode 11a forms an angle of less than 90° with the reference alignment direction.

[0054] The electrode side SD1 (referred to as the "upper electrode side") located at the upper end of the unit pixel electrode 11a extends in the horizontal direction of the display surface (the left - right direction in FIG. 7), so the direction e1 is the 270° direction. Therefore, the angle θ1 formed by the direction e1 and the reference alignment direction RD is 115.25°. Therefore, the upper electrode side SD1 is a first electrode side.

[0055] The electrode side SD2 (referred to as the "right electrode side") located at the right end of the unit pixel electrode 11a extends in the vertical direction of the display surface (the up - down direction in FIG. 7), so the direction e2 is the 180° direction. Therefore, the angle θ2 formed by the direction e2 and the reference alignment direction RD is 154.75°. Therefore, the right electrode side SD2 is a first electrode side.

[0056] Since the electrode side (referred to as the "lower electrode side") SD3 located at the lower end of the unit pixel electrode 11a extends in the horizontal direction of the display surface (the left-right direction in FIG. 7), the direction e3 is the 90° direction. Therefore, the angle θ3 formed by the direction e3 and the reference alignment direction RD is 64.75°. Thus, the lower electrode side SD3 is the second electrode side.

[0057] Since the electrode side (referred to as the "left electrode side") SD4 located at the left end of the unit pixel electrode 11a extends in the vertical direction of the display surface (the up-down direction in FIG. 7), the direction e4 is the 0° direction. Therefore, the angle θ4 formed by the direction e4 and the reference alignment direction RD is 25.25°. Thus, the left electrode side SD4 is the second electrode side.

[0058] As described above, the upper electrode side SD1 and the right electrode side SD2 are the first electrode sides, and the lower electrode side SD3 and the left electrode side SD4 are the second electrode sides. When a voltage is applied to the liquid crystal layer 30, disclination lines are generated in the vicinity of the first electrode sides. In contrast, no disclination lines are generated in the vicinity of the second electrode sides.

[0059] The above-described disclination lines are not observed when the liquid crystal display device 100 is provided with the circular polarizing plates 40A and 40B, but can be observed when a pair of linear polarizing plates are provided instead of the circular polarizing plates 40A and 40B. FIG. 8 shows an example of the disclination line DL observed when a pair of linear polarizing plates are provided. Here, the polarization axes PA1 and PA2 of the pair of linear polarizing plates are parallel to the horizontal direction of the display surface and the vertical direction of the display surface, respectively. As shown in FIG. 8, disclination lines DL are generated in the vicinity of the upper electrode side SD1 and the right electrode side SD2, while no disclination lines DL are generated in the vicinity of the lower electrode side SD3 and the left electrode side SD4.

[0060] Figs. 9A and 9B are diagrams for explaining the cause of the occurrence of the disclination line DL. Fig. 9A shows the alignment direction (the tilt direction of the liquid crystal molecules 31 near the center in the thickness direction of the liquid crystal layer 30 when a voltage is applied) defined by the first alignment film 15 and the second alignment film 25, and Fig. 9B shows the alignment direction by the oblique electric field near the outer edge of the unit pixel electrode 11a.

[0061] The liquid crystal molecules 31 within the pixel P (within the unit pixel Up) are basically controlled in their alignment direction by the alignment regulating forces of the first alignment film 15 and the second alignment film 25 as shown in Fig. 9A. However, the liquid crystal molecules 31 near the outer edge of the unit pixel electrode 11a are subject to the alignment regulating force by the oblique electric field generated near the electrode sides SD1 to SD4, so they can take an alignment state different from the alignment by the alignment regulating forces of the first alignment film 15 and the second alignment film 25 as shown in Fig. 9B. Therefore, the alignment state of the liquid crystal molecules 31 within the unit pixel Up is affected by both the alignment regulating forces of the first alignment film 15 and the second alignment film 25 and the alignment regulating force by the oblique electric field near the electrode sides SD1 to SD4. Near the upper electrode side SD1 and the right electrode side SD2, since the misalignment of the alignment direction is large, as shown in Fig. 8, the disclination line DL occurs.

[0062] In the region where the disclination line DL occurs, different alignment regulating forces are in competition, so the alignment orientation is likely to change due to a voltage change caused by the inversion of the polarity of the voltage applied to the liquid crystal layer 30, or a difference in minute offset voltages between different polarities. That is to say, the region where the disclination line DL occurs can be said to be a region with unstable alignment.

[0063] In the observation from the front direction in the configuration provided with the circular polarizing plate, the change in the alignment orientation during the polarity inversion as described above is hardly optically visible. However, in the observation from an oblique direction, since the apparent retardation and the axis angle of the circular polarizing plate are different from those in the front direction (i.e., an ideal circular polarizing plate), the change in the alignment orientation (instability of the liquid crystal alignment) as described above is visually recognized as flicker.

[0064] In the liquid crystal display device 100 of the present embodiment, in the unit pixel Up, the transmission region Tr is displaced and arranged on the side opposite to the reference alignment direction RD with respect to the center cp of the unit pixel Up. Therefore, as shown in FIG. 7, each of the distance d3 from the lower electrode side SD3 to the transmission region Tr and the distance d4 from the left electrode side SD4 to the transmission region Tr is smaller than each of the distance d1 from the upper electrode side SD1 to the transmission region Tr and the distance d2 from the right electrode side SD2 to the transmission region Tr. That is, the transmission region Tr is shifted toward the second electrode side where no disclination line DL is generated in the vicinity thereof. In other words, it is separated from the first electrode side where the disclination line DL is generated in the vicinity thereof. Therefore, flicker when observing the transmissive display from an oblique direction is suppressed, and the display quality is improved.

[0065] Here, as shown in FIG. 9C, consider four regions R1, R2, R3, and R4 obtained by bisecting the unit pixel Up in the row direction (the horizontal direction of the display surface, the left-right direction in the figure) and also in the column direction (the vertical direction of the display surface, the up-down direction in the figure). The region R1 including the portion located in the 0° to 90° direction with respect to the center cp of the unit pixel Up is called the "first quadrant region", and the region R2 including the portion located in the 90° to 180° direction is called the "second quadrant region". Similarly, the region R3 including the portion located in the 180° to 270° direction with respect to the center cp of the unit pixel Up is called the "third quadrant region", and the region R4 including the portion located in the 270° to 360° (0°) direction is called the "fourth quadrant region".

[0066] In the example where the reference alignment direction RD is in the 25.25° direction, the first quadrant region R1 is a region including two first electrode sides. Also, the second quadrant region R2 and the fourth quadrant region R4 are regions each including one first electrode side, and the third quadrant region R3 is a region not including the first electrode side. From the viewpoint of more surely suppressing flicker, it is preferable that the transmission region Tr is not included in the first quadrant region R1. Further, it is more preferable that the transmission region Tr is included only in the second quadrant region R2 and the third quadrant region R3, or only in the third quadrant region R3 and the fourth quadrant region R4, and it is even more preferable that the transmission region Tr is included only in the third quadrant region R3.

[0067] In the liquid crystal display device 100 of the present embodiment, the reflection region Rf may include a region where the disclination line DL is generated. However, since the reflection region Rf is larger than the transmission region Tr, the influence of the change in the alignment direction at the time of polarity inversion is relatively small. Also, originally, flicker itself is relatively difficult to visually recognize in reflection display, so it can be said that the concern about the deterioration of flicker during reflection display is small.

[0068] FIG. 10 shows one pixel P of a liquid crystal display device 900 of a comparative example. The liquid crystal display device 900 of the comparative example is different from the liquid crystal display device 100 of the present embodiment in the arrangement of the transmission region Tr in the unit pixel Up.

[0069] In the liquid crystal display device 900 of the comparative example, as a result of simply using the region where the wiring of the backplane circuit is not provided as the transmission region Tr, the positions of the transmission regions Tr in the three unit pixels Up are not aligned. As shown in FIG. 10, in the unit pixel Up located in the center of the figure and the unit pixel Up located on the lower side, the transmission region Tr is not displaced to the side opposite to the reference alignment direction RD with respect to the center cp of the unit pixel Up. Therefore, as shown in FIG. 11, the transmission region Tr may be located near the disclination line DL. Although FIG. 11 shows the unit pixel Up located on the lower side in FIG. 10, the same applies to the unit pixel Up located in the center in FIG. 10. Thus, when the transmission region Tr is located near the disclination line DL, there is a possibility that flicker may be visually recognized when the transmissive display is observed from an oblique direction.

[0070] On the other hand, in the liquid crystal display device 100 of the present embodiment, since the transmission region Tr is displaced to the side opposite to the reference alignment direction RD with respect to the center cp of the unit pixel Up, flicker when the transmissive display is observed from an oblique direction is suppressed.

[0071] [Verification Results of Flicker Suppression Effect] The liquid crystal display device 100 of the present embodiment was manufactured (Example), and the results of verifying the improvement effect of flicker will be described.

[0072] The screen size of the manufactured liquid crystal display device 100 was 1.2 type, and the size of one pixel P was 126 μm in length and 42 μm in width. The first alignment film 15 of the TFT substrate 10 and the second alignment film 25 of the counter substrate 20 were subjected to rubbing treatment as the alignment treatment. As described with reference to FIG. 6, the pretilt azimuth PD1 by the first alignment film 15 is in the 65° direction, the pretilt azimuth PD2 by the second alignment film 25 is in the 165.5° direction, and the direction RD of the director of the liquid crystal domain is in the 25.25° direction.

[0073] The thickness (cell gap) of the liquid crystal layer 30 is 3 μm in both the transmission region Tr and the reflection region Rf. A chiral agent was added to the liquid crystal material of the liquid crystal layer 30 to stably and uniquely determine the twist direction. The voltage applied to the liquid crystal layer 30 was set to 0 V during black display and ±3.2 V during white display. The driving frequency was set to 0.5 Hz.

[0074] When microscopic observation was performed using a linear polarizer as the polarizer, disclination lines DL were generated near the upper electrode side SD1 and the right electrode side SD2 of the unit pixel electrode 11a during white display, and changes in the disclination line DL and the alignment state around it were visually recognized corresponding to the polarity inversion.

[0075] Next, when microscopic observation was performed using circular polarizers 40A and 40B as the polarizers, no changes in the disclination line DL or the alignment state were visually recognized near the upper electrode side SD1 and the right electrode side SD2. As can be understood from this, for a liquid crystal display device that originally uses a circular polarizer, by performing alignment observation using a linear polarizer, the preferred arrangement of the transmission region Tr can be determined.

[0076] Regarding the example, flicker was measured when observing white display in the transmission mode from the front direction (polar angle is 0°) and the diagonal direction (polar angle is 60° and azimuth angle is 225°). The measurement results are shown in FIGS. 12 and 13. FIG. 12 is a graph showing the luminance change with respect to time when observed from the front direction, and FIG. 13 is a graph showing the luminance change with respect to time when observed from the diagonal direction.

[0077] When the flicker value in the front direction was obtained by the contrast method from the results shown in FIG. 12, it was -19.32 dB. Also, when the flicker value in the diagonal direction was obtained by the contrast method from the results shown in FIG. 13, it was -14.82 dB. These flicker values were all at levels that could not be recognized visually.

[0078] For comparison, a liquid crystal display device 900 of a comparative example was also fabricated and the same measurements were performed. The measurement results are shown in FIGS. 14 and 15. FIG. 14 is a graph showing the luminance change with respect to time when observed from the front direction, and FIG. 15 is a graph showing the luminance change with respect to time when observed from an oblique direction.

[0079] When the flicker value in the front direction was obtained by the contrast method from the results shown in FIG. 14, it was -19.26 dB, which was at a level not recognizable by the naked eye. However, when the flicker value in the oblique direction was obtained by the contrast method from the results shown in FIG. 15, it was -9.80 dB, which was at a level clearly recognizable by the naked eye.

[0080] Thus, it was confirmed that the liquid crystal display device 100 of the present embodiment can obtain an effect of improving flicker.

[0081] In the above description, the case where the reference alignment direction RD is in the 25.25° direction was exemplified. Of course, the reference alignment direction RD is not limited to this. Depending on the azimuth of the reference alignment direction RD, which of the electrode sides SD1 to SD4 correspond to the "first electrode side" and the "second electrode side" is determined. Therefore, the transmission region Tr may be moved away from the "first electrode side" and closer to the "second electrode side".

[0082] When the reference alignment direction RD is in a direction greater than 0° and less than 90°, the upper electrode side SD1 and the right electrode side SD2 are the first electrode sides, and the lower electrode side SD3 and the left electrode side SD4 are the second electrode sides. Therefore, the distances d3 from the lower electrode side SD3 to the transmission region Tr and d4 from the left electrode side SD4 to the transmission region Tr may be made smaller than the distances d1 from the upper electrode side SD1 to the transmission region Tr and d2 from the right electrode side SD2 to the transmission region Tr, respectively.

[0083] When the reference alignment direction RD is in a direction greater than 90° and less than 180°, the upper electrode side SD1 and the left electrode side SD4 are the first electrode sides, and the right electrode side SD2 and the lower electrode side SD3 are the second electrode sides. Therefore, each of the distance d2 from the right electrode side SD2 to the transmission region Tr and the distance d3 from the lower electrode side SD3 to the transmission region Tr may be made smaller than each of the distance d1 from the upper electrode side SD1 to the transmission region Tr and the distance d4 from the left electrode side SD4 to the transmission region Tr.

[0084] When the reference alignment direction RD is in a direction greater than 180° and less than 270°, the lower electrode side SD3 and the left electrode side SD4 are the first electrode sides, and the upper electrode side SD1 and the right electrode side SD2 are the second electrode sides. Therefore, each of the distance d1 from the upper electrode side SD1 to the transmission region Tr and the distance d2 from the right electrode side SD2 to the transmission region Tr may be made smaller than each of the distance d3 from the lower electrode side SD3 to the transmission region Tr and the distance d4 from the left electrode side SD4 to the transmission region Tr.

[0085] When the reference alignment direction RD is in a direction greater than 270° and less than 360°, the right electrode side SD2 and the lower electrode side SD3 are the first electrode sides, and the upper electrode side SD1 and the left electrode side SD4 are the second electrode sides. Therefore, each of the distance d1 from the upper electrode side SD1 to the transmission region Tr and the distance d4 from the left electrode side SD4 to the transmission region Tr may be made smaller than each of the distance d2 from the right electrode side SD2 to the transmission region Tr and the distance d3 from the lower electrode side SD3 to the transmission region Tr.

[0086] Note that flicker is likely to be observed when performing low-frequency driving. Therefore, the embodiment of the present invention can be said to be of great significance in a liquid crystal display device in which low-frequency driving is performed (for example, it can be driven at a driving frequency of 30 Hz or less).

[0087] [Shape of the transmission region] There is no particular limitation on the shape of the transmission region Tr in plan view. FIGS. 16A, 16B, and 16C show examples of the shape of the transmission region Tr.

[0088] In any of the examples shown in FIGS. 16A, 16B, and 16C, the unit pixel Up is substantially square-shaped. In the example shown in FIG. 16A, the transmission region Tr is substantially square-shaped. In contrast, in the example shown in FIG. 16B, the transmission region Tr is substantially rectangular with a width in the row direction (the horizontal direction of the display surface, the left-right direction in the figure) smaller than the width in the column direction (the vertical direction of the display surface, the up-down direction in the figure). In the example shown in FIG. 16C, the transmission region Tr is substantially rectangular with a width in the row direction larger than the width in the column direction.

[0089] As the shape of the transmission region Tr, any of the examples shown in FIGS. 16A, 16B, and 16C may be adopted. However, from the viewpoint of equally distancing the transmission region Tr from the two disclination lines DL generated in the vicinity of the first electrode sides (here, the upper electrode side SD1 and the right electrode side SD2), as in the example shown in FIG. 16A, it is preferable that the transmission region Tr has a shape substantially similar to the shape of the unit pixel Up in plan view.

[0090] [Embodiment 2] The liquid crystal display device 200 in the present embodiment will be described with reference to FIGS. 17 and 18. FIG. 17 is a plan view showing a region corresponding to one pixel P of the liquid crystal display device 200. FIG. 18 is a diagram showing the pretilt direction PD1 defined by the first alignment film 15 of the TFT substrate 10, the pretilt direction PD2 defined by the second alignment film 25 of the counter substrate 20, and the reference alignment direction RD. Hereinafter, the description will focus on the differences between the liquid crystal display device 200 of the present embodiment and the liquid crystal display device 100 in Embodiment 1.

[0091] In this embodiment, as shown in FIG. 18, the pretilt direction PD2 by the second alignment film 25 is antiparallel to the pretilt direction PD1 by the first alignment film 15. Specifically, the pretilt direction PD1 by the first alignment film 15 is in the 25.25° direction, the pretilt direction PD2 by the second alignment film 25 is in the 205.25° direction, and the reference alignment direction RD is in the 25.25° direction, the same as that of the liquid crystal display device 100 of Embodiment 1. No chiral agent is added to the liquid crystal material, and the liquid crystal layer 30 does not take a twist alignment when a voltage is applied and when no voltage is applied.

[0092] Also in the liquid crystal display device 200 of this embodiment, as shown in FIG. 17, in the unit pixel Up, the transmission region Tr is displaced to the side opposite to the reference alignment direction RD with respect to the center cp of the unit pixel Up. Therefore, the transmission region Tr is shifted toward the second electrode sides (the lower electrode side SD3 and the left electrode side SD4) where no disclination line DL is generated in the vicinity thereof, and is separated from the first electrode sides (the upper electrode side SD1 and the right electrode side SD2) where the disclination line DL is generated in the vicinity thereof. Therefore, flicker when observing the transmissive display from an oblique direction is suppressed.

[0093] In the liquid crystal display device 200 of this embodiment, the cell gap dt of the transmission region Tr and the cell gap dr of the reflection region Rf may be substantially the same as those of the liquid crystal display device 100 of Embodiment 1. Also, unlike the liquid crystal display device 100 of Embodiment 1, the cell gap dt of the transmission region Tr may be larger than the cell gap dr of the reflection region Rf.

[0094] Also, the cell gap in at least one of R the red pixel P G the green pixel P B and the blue pixel P R may be different from the cell gap in at least one of the others. The cell gap of the red pixel P G the cell gap of the green pixel P B the cell gap of the blue pixel P R are respectively "dG 」, "d" B When expressed as "", for example, d R > d G = d B , d R = d G > d B , or d R > d G > d B may be.

[0095] [Embodiment 3] With reference to FIGS. 19 and 20, the liquid crystal display device 300 in this embodiment will be described. FIG. 19 is a plan view showing a region corresponding to one pixel P of the liquid crystal display device 300. FIG. 20 is a diagram showing the pretilt direction PD1 defined by the first alignment film 15 of the TFT substrate 10, the pretilt direction PD2 defined by the second alignment film 25 of the counter substrate 20, and the reference alignment direction RD. Hereinafter, the description will focus on the differences between the liquid crystal display device 300 of this embodiment and the liquid crystal display device 100 in Embodiment 1.

[0096] In the liquid crystal display device 300 of this embodiment, the liquid crystal layer 30 is formed of a positive-type (i.e., dielectric anisotropy is positive) liquid crystal material. Also, each of the first alignment film 15 and the second alignment film 25 is a horizontal alignment film. Thus, the liquid crystal layer 30 is a horizontally aligned liquid crystal layer.

[0097] Also, in this embodiment, as shown in FIG. 20, the pretilt direction PD2 by the second alignment film 25 is antiparallel to the pretilt direction PD1 by the first alignment film 15. Specifically, the pretilt direction PD1 by the first alignment film 15 is in the 25.25° direction, the pretilt direction PD2 by the second alignment film 25 is in the 205.25° direction, and the reference alignment direction RD is in the 25.25° direction, the same as that of the liquid crystal display device 100 in Embodiment 1.

[0098] In the liquid crystal display device 300 of the present embodiment, as shown in FIG. 19, in the unit pixel Up, the transmission region Tr is disposed so as to be shifted toward the reference alignment direction RD with respect to the center cp of the unit pixel Up. Therefore, as shown in FIG. 21, each of the distance d1 from the upper electrode side SD1 to the transmission region Tr and the distance d2 from the right electrode side SD2 to the transmission region Tr is smaller than each of the distance d3 from the lower electrode side SD3 to the transmission region Tr and the distance d4 from the left electrode side SD4 to the transmission region Tr.

[0099] In the present embodiment, since the liquid crystal layer 30 is formed of a positive-type liquid crystal material, the alignment direction due to the oblique electric field in the vicinity of the outer edge of the unit pixel electrode 11a is opposite to the case where the liquid crystal layer 30 is formed of a negative-type liquid crystal material. Therefore, as shown in FIG. 22, a disclination line DL is generated in the vicinity of the lower electrode side SD3 and the left electrode side SD4, which are the second electrode sides, whereas no disclination line DL is generated in the vicinity of the upper electrode side SD1 and the right electrode side SD2, which are the first electrode sides. As already described, the transmission region Tr is disposed so as to be shifted toward the reference alignment direction RD with respect to the center cp of the unit pixel Up. Therefore, the transmission region Tr is shifted toward the first electrode side (the upper electrode side SD1 and the right electrode side SD2) where no disclination line DL is generated in the vicinity thereof, and is separated from the second electrode side (the lower electrode side SD3 and the left electrode side SD4) where the disclination line DL is generated in the vicinity thereof. Therefore, flicker when observing the transmissive display from an oblique direction is suppressed.

[0100] Here, considering the four regions R1, R2, R3, and R4 shown in FIG. 9C, in the example where the reference alignment direction RD is in the 25.25° direction, the third quadrant region R3 is a region including two second electrode sides. Also, the second quadrant region R2 and the fourth quadrant region R4 are regions each including one second electrode side, and the first quadrant region R1 is a region not including the second electrode side. From the viewpoint of more reliably suppressing flicker, it is preferable that the transmission region Tr is not included in the third quadrant region R3. Further, it is more preferable that the transmission region Tr is included only in the first quadrant region R1 and the second quadrant region R2, or only in the first quadrant region R1 and the fourth quadrant region R4, and it is even more preferable that the transmission region Tr is included only in the first quadrant region R1.

[0101] In addition, in this embodiment, the case where the reference alignment direction RD is in the 25.25° direction is illustrated, but of course the reference alignment direction RD is not limited thereto. Depending on the azimuth of the reference alignment direction RD, which of the electrode sides SD1 to SD4 correspond to the "first electrode side" and the "second electrode side" is determined, so the transmission region Tr may be moved away from the "second electrode side" and closer to the "first electrode side".

[0102] When the reference alignment direction RD is in a direction greater than 0° and less than 90°, the upper electrode side SD1 and the right electrode side SD2 are the first electrode sides, and the lower electrode side SD3 and the left electrode side SD4 are the second electrode sides. Therefore, each of the distance d1 from the upper electrode side SD1 to the transmission region Tr and the distance d2 from the right electrode side SD2 to the transmission region Tr may be made smaller than each of the distance d3 from the lower electrode side SD3 to the transmission region Tr and the distance d4 from the left electrode side SD4 to the transmission region Tr.

[0103] When the reference alignment direction RD is in a direction greater than 90° and less than 180°, the upper electrode side SD1 and the left electrode side SD4 are the first electrode sides, and the right electrode side SD2 and the lower electrode side SD3 are the second electrode sides. Therefore, each of the distance d1 from the upper electrode side SD1 to the transmission region Tr and the distance d4 from the left electrode side SD4 to the transmission region Tr may be made smaller than each of the distance d2 from the right electrode side SD2 to the transmission region Tr and the distance d3 from the lower electrode side SD3 to the transmission region Tr.

[0104] When the reference alignment direction RD is in a direction greater than 180° and less than 270°, the lower electrode side SD3 and the left electrode side SD4 are the first electrode sides, and the upper electrode side SD1 and the right electrode side SD2 are the second electrode sides. Therefore, each of the distance d3 from the lower electrode side SD3 to the transmission region Tr and the distance d4 from the left electrode side SD4 to the transmission region Tr may be made smaller than each of the distance d1 from the upper electrode side SD1 to the transmission region Tr and the distance d2 from the right electrode side SD2 to the transmission region Tr.

[0105] When the reference alignment direction RD is in a direction greater than 270° and less than 360°, the right electrode side SD2 and the lower electrode side SD3 are the first electrode sides, and the upper electrode side SD1 and the left electrode side SD4 are the second electrode sides. Therefore, each of the distance d2 from the right electrode side SD2 to the transmission region Tr and the distance d3 from the lower electrode side SD3 to the transmission region Tr may be made smaller than each of the distance d1 from the upper electrode side SD1 to the transmission region Tr and the distance d4 from the left electrode side SD4 to the transmission region Tr.

[0106] Also in the liquid crystal display device 300 of the present embodiment, there is no particular limitation on the shape of the transmission region Tr in plan view. However, from the viewpoint of equally distancing the transmission region Tr from the two disclination lines DL generated in the vicinity of the second electrode side, it is preferable that the transmission region Tr has a shape substantially similar to the shape of the unit pixel Up in plan view.

[0107] [Other aspects] Here, a backplane circuit having a memory circuit for each pixel P has been exemplified, but the backplane circuit is not limited to this example. The backplane circuit may include a TFT connected to the pixel electrode 11 and a gate bus line, a source bus line, etc. connected to the TFT, like a general active matrix substrate. The TFT is, for example, a TFT having, as an active layer, an amorphous silicon layer, a polysilicon layer, or an oxide semiconductor layer containing an In-Ga-Zn-O-based semiconductor (see Japanese Patent Application Laid-Open No. 2014-007399). Japanese Patent Application Laid-Open No. 2014-007399 is incorporated herein by reference for reference purposes.

[0108] Also, although a configuration in which each pixel P includes a plurality of unit pixels Up has been exemplified, each pixel P may include only one unit pixel Up. In that case, the entire pixel electrode 11 is a single unit pixel electrode 11a.

Industrial Applicability

[0109] The embodiments of the present invention can be widely applied to a liquid crystal display device (i.e., a transflective liquid crystal display device) in which each pixel includes a reflective region for performing display in a reflective mode and a transmissive region for performing display in a transmissive mode.

Explanation of Reference Numerals

[0110] 10 TFT substrate 10a substrate 11 pixel electrode 11a unit pixel electrode 12 reflective layer 12a first region 12b second region 12o opening 13 first interlayer insulating layer 14 second interlayer insulating layer 15 first alignment film 16 first contact electrode 17 second contact electrode 18 third contact electrode 20 counter substrate 20a substrate 21 counter electrode 25 second alignment film 30 Liquid crystal layer 31 Liquid crystal molecules 40A, 40B Circular polarizing plates 50 Lighting device (backlight) 51 Light source 52 Light guide plate 53 Reflector 100, 200, 300 Liquid crystal display devices P pixel P R Red pixel P G Green pixel P B Blue pixel Up unit pixel Rf Reflection region Tr Transmission region RD Reference alignment direction CP Contact part CH1 First contact hole CH2 Second contact hole SD1, SD2, SD3, SD4 Electrode sides R1 First quadrant region R2 Second quadrant region R3 Third quadrant region R4 Fourth quadrant region

Claims

1. a first substrate, a second substrate facing the first substrate, a liquid crystal layer provided between the first substrate and the second substrate, a pair of circular polarizing plates facing each other at least through the liquid crystal layer, comprising a liquid crystal display device having a plurality of pixels arranged in a matrix, the first substrate has pixel electrodes provided for each of the plurality of pixels, when a voltage is applied to the liquid crystal layer, the liquid crystal layer takes a monodomain alignment in which at least one type of liquid crystal domain is formed in each of the plurality of pixels, each of the pixel electrodes includes at least one unit pixel electrode on which the liquid crystal domain is formed, each of the plurality of pixels includes at least one unit pixel which is a region corresponding to the at least one unit pixel electrode, the unit pixel includes a reflection region for performing display in a reflection mode and a transmission region for performing display in a transmission mode, the transmission region having an area smaller than the area of the reflection region in plan view, the outer edge of the unit pixel electrode includes at least one first electrode side and at least one second electrode side, when the direction of the director of the liquid crystal domain is referred to as a reference alignment direction, the direction perpendicular to the first electrode side and toward the inside of the unit pixel electrode forms an angle greater than 90° with the reference alignment direction, the direction perpendicular to the second electrode side and toward the inside of the unit pixel electrode forms an angle less than 90° with the reference alignment direction, the liquid crystal layer is formed of a negative liquid crystal material, and in the unit pixel, the distance from the second electrode side to the transmission region is smaller than the distance from the first electrode side to the transmission region, or the liquid crystal layer is formed of a positive liquid crystal material, and in the unit pixel, the distance from the first electrode side to the transmission region is smaller than the distance from the second electrode side to the transmission region, a liquid crystal display device.

2. a first substrate, a second substrate facing the first substrate, a liquid crystal layer provided between the first substrate and the second substrate, a pair of circular polarizing plates facing each other at least through the liquid crystal layer, comprising a liquid crystal display device having a plurality of pixels arranged in a matrix, the first substrate has pixel electrodes provided for each of the plurality of pixels, When a voltage is applied to the liquid crystal layer, the liquid crystal layer has a monodomain alignment in which at least one type of liquid crystal domain is formed in each of the plurality of pixels. Each of the pixel electrodes includes at least one unit pixel electrode on which the liquid crystal domain is formed. Each of the plurality of pixels includes at least one unit pixel which is a region corresponding to the at least one unit pixel electrode. The unit pixel includes a reflection region for performing display in a reflection mode and a transmission region for performing display in a transmission mode, the transmission region having an area smaller than the area of the reflection region in a plan view. When the direction of the director of the liquid crystal domain is called a reference alignment direction, the liquid crystal layer is formed of a negative liquid crystal material, and in the unit pixel, the transmission region is displaced to the side opposite to the reference alignment direction with respect to the center of the unit pixel, or the liquid crystal layer is formed of a positive liquid crystal material, and in the unit pixel, the transmission region is displaced to the reference alignment direction side with respect to the center of the unit pixel, a liquid crystal display device.

3. The liquid crystal display device according to claim 1 or 2, which can be driven at a driving frequency of 30 Hz or less.

4. The liquid crystal display device according to claim 1 or 2, wherein in each of the plurality of pixels, the thickness of the liquid crystal layer in the reflection region and the thickness of the liquid crystal layer in the transmission region are substantially the same.

5. The liquid crystal layer does not take a twist alignment, The liquid crystal display device according to claim 1 or 2, wherein in each of the plurality of pixels, the thickness of the liquid crystal layer in the transmission region is larger than the thickness of the liquid crystal layer in the reflection region.

6. The plurality of pixels include a red pixel for displaying red, a green pixel for displaying green, and a blue pixel for displaying blue, The liquid crystal display device according to claim 5, wherein the thickness of the liquid crystal layer in at least one of the red pixel, the green pixel, and the blue pixel is different from the thickness of the liquid crystal layer in at least one other of them.

7. The liquid crystal display device according to claim 1 or 2, further comprising a memory circuit connected to each of the plurality of pixels.

8. In each of the at least one unit pixel, The liquid crystal display device according to claim 1 or 2, wherein the transmission region has a shape substantially similar to the shape of the unit pixel in a plan view.

Images