CN118112832A

CN118112832A - Liquid crystal display device having a light shielding layer

Info

Publication number: CN118112832A
Application number: CN202311406479.4A
Authority: CN
Inventors: 本多真理子; 和歌伸浩; 箱井博之; 佐佐木贵启; 佐藤孝; 坂井彰; 前田诚二
Original assignee: Sharp Display Technology Corp
Current assignee: Sharp Display Technology Corp
Priority date: 2022-11-29
Filing date: 2023-10-26
Publication date: 2024-05-31

Abstract

The invention provides a semi-transmissive liquid crystal display device which suppresses occurrence of display failure due to uneven cell gap. The liquid crystal display device includes a first substrate, a second substrate, and a liquid crystal layer. Each pixel includes a reflective region and a transmissive region. The first substrate has a reflective layer, an interlayer insulating layer provided so as to cover the reflective layer, and pixel electrodes provided on the interlayer insulating layer in each pixel. The interlayer insulating layer has a recess defined by a bottom surface and an inclined side surface, and at least a part of the recess is located in the transmissive region. The depth of the recess of the interlayer insulating layer is 0.5 μm or more, and the inclination angle of the inclined side surface of the recess is 25 DEG or less.

Description

Liquid crystal display device having a light shielding layer

Technical Field

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

Background

In recent years, as a display device for a digital signage for smart watches and for outdoor advertising, a semi-transmissive (also sometimes referred to as "transflective") liquid crystal display device (LCD) has been used. The transflective LCD has, in one pixel, a reflective area for performing display in a reflective mode (reflective display) and a transmissive area for performing display in a transmissive mode (transmissive display). Therefore, high visibility can be obtained in an outdoor environment under sunlight by using reflective display of external light, and information can be confirmed at night by using transmissive display of backlight.

The applicant of the present application has proposed a transflective LCD capable of improving brightness of a reflective display and a transmissive display in patent document 1. In the transflective LCD disclosed in patent document 1, the reflectance is improved by a two-stage electrode structure in which a reflective electrode (reflective layer) and a transparent electrode (pixel electrode) are separated by an interlayer insulating layer. In addition, in patent document 1, a multi-gap structure in which the cell gap in the reflective region and the cell gap in the transmissive region are different is also mentioned. By adopting the multi-gap structure, the transmittance is improved.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2021-96461

Disclosure of Invention

The invention aims to solve the technical problems

However, according to the study of the present inventors, it is found that in a semi-transmissive LCD having a multi-gap structure, the cell gap varies from pixel to pixel, and there is a possibility that display failure may occur due to this.

The present invention has been made in view of the above problems, and an object thereof is to provide a semi-transmissive liquid crystal display device that suppresses occurrence of display failure due to cell gap unevenness.

Solution to the problem

The present specification discloses a display device described in the following items.

[ Item 1]

A liquid crystal display device, comprising:

A first substrate;

A second substrate facing the first substrate; and

A liquid crystal layer provided between the first substrate and the second substrate, and having a plurality of pixels including a plurality of rows and a plurality of columns and arranged in a matrix,

Each of the plurality of pixels includes a reflective region for displaying in a reflective mode and a transmissive region for displaying in a transmissive mode,

The first substrate has:

A reflective layer;

An interlayer insulating layer provided so as to cover the reflective layer; and

A pixel electrode provided on the interlayer insulating layer in each of the plurality of pixels,

The interlayer insulating layer has a recess defined by a bottom surface and an inclined side surface, and at least a portion is located in the transmissive region,

The depth of the recess of the interlayer insulating layer is 0.5 μm or more,

The inclined side surface of the recess has an inclination angle of 25 ° or less.

[ Item 2]

The liquid crystal display device according to item 1, wherein an inclination angle of the inclined side surface of the concave portion is 22 ° or less.

[ Item 3]

The liquid crystal display device according to item 1 or 2, wherein the bottom surface and the inclined side surface of the concave portion are located in the transmissive region.

[ Item 4]

The liquid crystal display device according to any one of items 1 to 3, wherein the reflective layer has a concave-convex surface structure.

[ Item 5]

The liquid crystal display device according to any one of items 1 to 3, wherein the reflective layer has a substantially flat surface.

[ Item 6]

The liquid crystal display device according to any one of items 1 to 5, wherein the liquid crystal layer is vertically aligned.

[ Item 7]

The liquid crystal display device according to any one of items 1 to 5, wherein the liquid crystal layer is horizontally aligned.

[ Item 8]

The liquid crystal display device according to any one of items 1 to 7, wherein the first substrate further has a back plate circuit that drives the plurality of pixels,

The interlayer insulating layer has a contact hole in the transmissive region for electrically connecting the pixel electrode with the back plate circuit.

[ Item 9]

The liquid crystal display device according to any one of items 1 to 8, wherein the transmissive region of each pixel includes a plurality of sub-transmissive regions spaced apart from each other,

The plurality of sub-transmissive regions includes: a first sub-transmission region including the contact hole; and a second sub-transmission region not including the contact hole.

[ Item 10]

The liquid crystal display device according to item 9, wherein each pixel includes a plurality of sub-pixels including: a first subpixel including the first sub-transmissive region; a second sub-pixel including the second sub-transmissive region,

The pixel electrode includes a plurality of sub-pixel electrodes,

The plurality of sub-pixel electrodes includes: a first subpixel electrode disposed on the first subpixel; a second subpixel electrode disposed on the second subpixel,

The first subpixel electrode is electrically connected with the second subpixel electrode.

[ Item 11]

The liquid crystal display device according to item 10, wherein the pixel electrode further includes a connection electrode that connects the first subpixel electrode and the second subpixel electrode, and the first subpixel electrode, the second subpixel electrode, and the connection electrode are U-shaped as a whole.

[ Item 12]

The liquid crystal display device according to item 11, wherein the plurality of sub-transmissive regions further includes a third sub-transmissive region including the contact hole,

The plurality of sub-pixels further includes a third sub-pixel including the third sub-transmissive region,

The plurality of subpixel electrodes further includes a third subpixel electrode disposed between the first subpixel electrode and the second subpixel electrode.

[ Item 13]

In the liquid crystal display device according to item 12, when the first subpixel electrode, the second subpixel electrode, and the connection electrode are referred to as a first electrode segment, the third subpixel electrode is referred to as a second electrode segment, and a gap between the first electrode segment and the second electrode segment is referred to as a segment boundary, the segment boundary has a curved shape.

[ Item 14]

In the liquid crystal display device according to item 13, a portion of the outer edge of the first electrode segment defining the segment boundary and a portion of the outer edge of the second electrode segment defining the segment boundary are each arc-shaped.

[ Item 15]

The liquid crystal display device according to any one of items 1 to 14, wherein the first substrate has an alignment film provided so as to be in contact with the liquid crystal layer.

[ Item 16]

The liquid crystal display device according to any one of items 1 to 15, wherein the plurality of pixels form a plurality of color display pixels each having three or more pixels exhibiting mutually different colors,

The resolution is more than 180ppi,

The size of each color display pixel is 140 μm by 140 μm or less,

The size of the transmission region is 30 μm×30 μm or less.

[ Item 17]

The liquid crystal display device according to any one of items 1 to 16, wherein a thickness of the liquid crystal layer in the reflection region is 2.0 μm or more and 2.5 μm or less,

The thickness of the liquid crystal layer in the transmissive region is 3.0 μm or more and 3.8 μm or less.

[ Item 18]

The liquid crystal display device according to any one of items 1 to 17, wherein the plurality of pixels includes 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 the reflective region of the blue pixel is smaller than the thickness of the liquid crystal layer in the reflective region of the red pixel and the thickness of the liquid crystal layer in the reflective region of the green pixel, respectively.

[ Project 19]

The liquid crystal display device according to item 18, wherein the second substrate has a color filter layer,

The color filter layer includes a red filter disposed on the red pixel, a green filter disposed on the green pixel, and a blue filter disposed on the blue pixel, wherein the thickness of the blue filter is greater than the thickness of the red filter and the thickness of the green filter, respectively.

Effects of the invention

According to the embodiment of the present invention, a semi-transmissive liquid crystal display device in which occurrence of display failure due to cell gap unevenness is suppressed can be provided.

Drawings

Fig. 1 is a plan view schematically showing a liquid crystal display device 100 according to an embodiment of the present invention, and shows regions of the liquid crystal display device 100 corresponding to three pixels P.

Fig. 2 is a sectional view schematically showing the liquid crystal display device 100, and shows a sectional structure along a line 2A-2A' in fig. 1.

Fig. 3 is a diagram showing an example of gray scale display using the configuration illustrated in fig. 1.

Fig. 4 is a diagram showing conditions at the time of calculation based on simulation.

Fig. 5 is a graph showing a relationship between a cell gap and a mode efficiency.

Fig. 6A is a top view showing photomask 70A.

Fig. 6B is a top view showing photomask 70B.

Fig. 7A is a diagram schematically showing a state in which the photosensitive resin material 13' is exposed using the photomask 70.

Fig. 7B is a diagram schematically showing the state of exposing the photosensitive resin material 13' using the photomask 70B.

Fig. 8A is a diagram for explaining the results of verifying the effect of including the slit portion in the light-transmitting region of the photomask.

Fig. 8B is a diagram for explaining the results of verifying the effect of including the slit portion in the light-transmitting region of the photomask.

Fig. 9 is a cross-sectional view showing another example of the structure of the liquid crystal display device 100.

Fig. 10 is a cross-sectional view showing still another example of the structure of the liquid crystal display device 100.

Fig. 11 is a cross-sectional view showing still another example of the structure of the liquid crystal display device 100.

Fig. 12 is a cross-sectional view showing still another example of the structure of the liquid crystal display device 100.

Fig. 13 is a plan view showing regions of the liquid crystal display device 100 corresponding to three pixels P.

Fig. 14 is a diagram showing an example of gray scale display using the configuration illustrated in fig. 13.

Fig. 15A is a diagram showing an example of actual character display in the case of adopting the electrode structure shown in fig. 1.

Fig. 15B is a diagram showing an example of actual character display in the case of adopting the electrode structure shown in fig. 13.

Fig. 16A is a diagram showing a modification of the shape of the first electrode segment es1 and the second electrode segment es 2.

Fig. 16B is a diagram showing a modification of the shape of the first electrode segment es1 and the second electrode segment es 2.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the following embodiments.

(Embodiment 1)

A liquid crystal display device 100 according to the present embodiment is described with reference to fig. 1 and 2. The liquid crystal display device 100 of the present embodiment is a transflective (transmissive and reflective type) liquid crystal display device. Fig. 1 is a plan view schematically showing the liquid crystal display device 100, and shows regions of the liquid crystal display device 100 corresponding to three pixels P. Fig. 2 is a sectional view schematically showing the liquid crystal display device 100, and shows a sectional structure along a line 2A-2A' in fig. 1.

As shown in fig. 1, the liquid crystal display device 100 has a plurality of pixels P. The plurality of pixels are arranged in a matrix including a plurality of rows and a plurality of columns. The plurality of pixels P typically includes a red pixel P _R that displays red, a green pixel P _G that displays green, and a blue pixel P _B that displays blue.

As shown in fig. 2, the liquid crystal display device 100 includes: a liquid crystal display panel LP, and a backlight (lighting device) BL disposed on the back side (opposite to the viewer side) of the liquid crystal display panel LP. The liquid crystal display panel LP includes a TFT substrate (first substrate) 10, a counter substrate (second substrate) 20 facing the TFT substrate 10, and a vertically aligned liquid crystal layer 30 provided between the TFT substrate 10 and the counter substrate 20. Each pixel P includes a reflection region Rf for displaying in the reflection mode and a transmission region Tr for displaying in the transmission mode.

The thickness (transmissive cell gap) dt of the liquid crystal layer 30 in the transmissive region Tr and the thickness (reflective cell gap) dr of the liquid crystal layer 30 in the reflective region Rf are different. Specifically, the transmissive cell gap dt is greater than the reflective cell gap dr (i.e., dt > dr). Thus, the liquid crystal display device 100 has a multi-gap structure. The reflective cell gap dr is, for example, 2.0 μm or more and 2.5 μm or less, and the transmissive cell gap dt is, for example, 3.0 μm or more and 3.8 μm or less.

The proportion of the area of the transmission region Tr in the pixel P may be appropriately set according to the application, for example, 10% or more and 90% or less. The position and shape of the transmission region Tr in the pixel P can be appropriately set according to the application and the like. In the present specification, the region Iv that does not contribute to the reflective display or the transmissive display in the pixel P is sometimes referred to as an "ineffective region".

The TFT substrate 10 includes a pixel electrode 11 disposed in each pixel P and a reflective layer 12 located on the opposite side of the liquid crystal layer 30 (i.e., on the back surface side of the pixel electrode 11) from 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.

The TFT substrate 10 has its constituent elements (the pixel electrode 11 and the like described above) supported by a transparent substrate 10 a. As a material of the transparent substrate 10a, alkali-free glass or plastic can be used, for example.

A circuit (back plate circuit) (not shown) for driving the plurality of pixels P is formed on the transparent substrate 10 a. The back plate circuit is not particularly limited. For example, the back plane circuit may include a memory circuit (for example, SRAM) connected to each of the plurality of pixels P. A liquid crystal display device provided with a memory circuit for each pixel P is sometimes also referred to as "memory liquid crystal". Specific structures of the memory liquid crystal are disclosed in, for example, japanese patent No. 5036864 (corresponding to the specification of us patent No. 8692758). The disclosure of japanese patent No. 5036864 and us patent No. 8692758 is incorporated by reference into this specification. Alternatively, the back plane circuit may include a Thin Film Transistor (TFT) connected to the pixel electrode 11 as in a general active matrix substrate. The TFT is, for example, a TFT having an amorphous silicon layer, a polysilicon layer, or an oxide semiconductor layer containing an In-Ga-Zn-O semiconductor as an active layer (see japanese patent application laid-open No. 2014-007599). For reference, japanese patent application laid-open No. 2014-007599 is incorporated herein by reference. The back plate circuit may include various wirings such as a gate wiring and a source wiring in addition to the memory circuit and the TFT.

The second interlayer insulating layer 14 is provided so as to cover the back plane circuit. The second interlayer insulating layer 14 is a transparent insulating layer, and is formed of, for example, a transparent organic insulating material. The surface of the second interlayer insulating layer 14 has a concave-convex shape. That is, the second interlayer insulating layer 14 has a concave-convex surface structure. The second interlayer insulating layer 14 having the uneven surface structure is formed using a photosensitive resin, for example, as described in japanese patent No. 3394926.

The reflective layer 12 is disposed on the second interlayer insulating layer 14. The reflective layer 12 is formed of a metal material having high reflectivity. As a metal material for forming the reflective layer 12, for example, aluminum, silver alloy, or the like can be used.

The surface of the reflective layer 12 has a concave-convex shape reflecting the concave-convex surface structure of the second interlayer insulating layer 14. That is, the reflective layer 12 also has a concave-convex surface structure. The uneven surface structure of the reflective layer 12 is also called MRS (Micro Reflective Structure: micro reflective structure) and is provided for performing diffuse reflection of ambient light to realize a display close to paper white. The uneven surface structure is constituted by, for example, a plurality of convex portions p arranged at random such that the center interval 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. The convex portion p has a substantially circular shape or a substantially polygonal shape when viewed from the normal direction of the display surface. The area occupied by the convex portion P in 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.

The reflective layer 12 includes a first portion 12a located in the reflective area Rf of each pixel P and a second portion 12b located between any two pixels P adjacent to each other. The concave-convex surface structures of the reflective layer 12 are formed at the first portion 12a and the second portion 12b, respectively. That is, not only the first portion 12a but also the second portion 12b has a concave-convex surface structure.

Further, the reflective layer 12 may not have a concave-convex surface structure (i.e., may have a substantially flat surface). When the reflective layer 12 does not have a concave-convex surface structure, display close to white paper can be achieved by using the reflective layer 12 and the light scattering layer in combination.

The first interlayer insulating layer 13 is provided so as to cover the reflective layer 12. The first interlayer insulating layer 13 is a transparent insulating layer, and is formed of, for example, a transparent organic insulating material. In the first interlayer insulating layer 13, a concave portion (transmission opening groove) TG for making the transmission cell gap dt larger than the reflection cell gap dr is formed by a photolithography process.

The pixel electrode 11 is disposed on the first interlayer insulating layer 13. That is, the pixel electrode 11 is provided on the reflective layer 12 via the first interlayer insulating layer 13. 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 the back plate circuit.

The contact portion CP electrically connects the pixel electrode 11 and the back plane circuit in 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. The first contact hole CH1 and the second contact hole CH2 are formed, for example, by a photolithography process. The first interlayer insulating layer 13 has a first contact hole CH1 in the transmission region Tr, and the second interlayer insulating layer 14 has a second contact hole CH2 in the transmission region Tr. In the illustrated example, the contact portion CP is constituted by a first contact electrode ce1, a second contact electrode ce2, and a third contact electrode ce 3.

The first contact electrode ce1 is an electrode (or a part of a wiring) exposed in the first contact hole CH 1. The first contact electrode ce1 is formed of, for example, the same conductive film (metal film such as aluminum or copper) as the source wiring of the back plate circuit.

The second contact electrode ce2 is a transparent contact electrode formed of a transparent conductive material (e.g., indium tin oxide, indium zinc oxide). The second contact electrode ce2 includes a portion located in the second contact hole CH2, and contacts the first contact electrode ce1 in the second contact hole CH 2.

The third contact electrode ce3 is a reflective contact electrode formed on the same layer as the reflective layer 12 (i.e., by the same reflective film as the reflective layer 12) so as to be in contact with the second contact electrode (transparent contact electrode) ce 2. The third contact electrode ce3 includes a portion overlapping the first contact hole CH 1. The pixel electrode 11 is in contact with the third contact electrode ce3 in the first contact hole CH1, and is electrically connected to the back plate circuit via the contact portion CP.

When the contact portion CP includes the reflective contact electrode ce3, the reflective contact electrode ce3 functions as a light shielding layer for light from the backlight BL, and therefore, when an alignment defect occurs in the vicinity of the first contact hole CH1, an adverse effect of the alignment defect on the quality of the transmissive display can be prevented.

In the illustrated example, since the contact portion CP includes the reflective contact electrode ce3, the region where the contact portion CP exists becomes the ineffective region IV, and the first contact hole CH1 and the second contact hole CH2 are strictly located in the ineffective region IV, not in the transmissive region Tr. However, in this case, since the contact portion CP is surrounded by the transmission region Tr, in the present specification, the first contact hole CH1 and the second contact hole CH2 may be included in the transmission region Tr in this case.

In the illustrated example, a transparent conductive layer 19 formed of the same conductive film as the second contact electrode ce2 (i.e., the same layer as the second contact electrode ce 2) is interposed between the reflective layer 12 and the second interlayer insulating layer 14. The transparent conductive layer 19 may also be omitted.

The counter substrate 20 has a counter electrode 21, a color filter layer 22, and a second alignment film 25. The counter substrate 20 further includes a plurality of columnar spacers (not shown). The constituent elements of the counter substrate 20 (the counter electrode 21 and the like described above) are supported by the transparent substrate 20 a. As a material of the transparent substrate 20a, alkali-free glass or plastic can be used, for example. Further, the counter substrate 20 does not have a black matrix (light shielding layer) between any two pixels P adjacent to each other.

The counter electrode 21 is provided so as to face the pixel electrode 11. 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. The reflection layer 12 is applied with the same potential (common potential) as that applied by the counter electrode 21, for example.

The color filter layer 22 typically includes a red color filter disposed at a red pixel, a green color filter disposed at a green pixel, and a blue color filter disposed at a blue pixel. The regions of the color filter layer corresponding to the pixels P of different colors are substantially equally divided by the color filters of different colors, for example. An overcoat layer may be formed so as to cover the color filter layer 22.

The columnar spacers define the thickness (cell gap) of the liquid crystal layer 30. The columnar spacers are formed of a photosensitive resin.

The liquid crystal layer 30 comprises a nematic liquid crystal material having negative dielectric anisotropy (i.e. negative), but does not comprise a chiral agent. The liquid crystal layer 30 can be formed by, for example, a one drop fill method.

The first alignment film 15 and the second alignment film 25 are provided so as to be in contact with the liquid crystal layer 30, respectively. That is, the first alignment film 15 and the second alignment film 25 are vertical alignment films, respectively. In the present specification, the "vertical alignment film" may be any film as long as the liquid crystal molecules in the vicinity of the alignment film are substantially vertically aligned with respect to the surface of the alignment film, and may be an alignment film that imparts a pretilt angle of 86.0 ° or more to the liquid crystal molecules, for example. The main component of the vertical alignment film is preferably polyimide, polyamic acid, polymaleimide, or polysiloxane, for example. They are a group of polymers that can be effectively used as an orientation film.

At least one of the first alignment film 15 and the second alignment film 25 is subjected to an alignment treatment to define a pretilt direction. As the alignment treatment, a rubbing treatment or a photo-alignment treatment can be used. An alignment film in which the strength and direction of an alignment regulating force for liquid crystal molecules are changed by photo-alignment treatment (light irradiation/exposure) is called a "photo-alignment film". The photo-alignment film preferably contains at least one of a cinnamate group, an azo phenyl group, a chalcone group, a stilbene group, and a coumarin group as a photoreactive functional group. This reduces the possibility of dissolution of the photodecomposition into the liquid crystal layer 30, thereby improving reliability and enabling the photoalignment treatment to be performed at a relatively low irradiation energy.

The liquid crystal molecules of the liquid crystal layer 30 are vertically aligned in a state where no voltage is applied to the liquid crystal layer 30, and are horizontally aligned in a state where a predetermined voltage is applied to the liquid crystal layer 30. In the present embodiment, the twist angle of the liquid crystal layer 30 is substantially 0 °, and the display is performed in a VA-ECB (VERTICAL ALIGNED ELECTRICALLY Controlled Birefringence: vertically aligned electrically controlled birefringence) mode. Further, "the torsion angle is substantially 0 °" also includes a case where the torsion angle approaches 0 ° within the range of manufacturing errors.

As the liquid crystal layer 30, a liquid crystal layer containing a nematic liquid crystal material whose dielectric constant anisotropy is positive (i.e., positive) can be used. In this case, the horizontal alignment film is used as the first alignment film 15 and the second alignment film 25, and the ECB mode is used as the display mode. Thus, the liquid crystal layer 30 may be of a horizontal alignment type.

The liquid crystal display device 100 further includes a pair of circularly polarizing plates 40A and 40B. One (first circular polarizing plate) 40A of the pair of circular polarizing plates 40A and 40B is disposed on the back surface side of the liquid crystal display panel LP, and the other (second circular polarizing plate) 40B is disposed on the viewer side of the liquid crystal display panel LP. The first circularly polarizing plate (back circularly polarizing plate) 40A includes a first linear polarizing plate 41A and a first phase difference plate 42A located between the first linear polarizing plate 41A and the liquid crystal display panel LP. The second circular polarizing plate (surface circular polarizing plate) 40B includes a second linear polarizing plate 41B, and a second phase difference plate 42B located between the second linear polarizing plate 41B and the liquid crystal display panel LP.

The second linear polarizing plate (surface linear polarizing plate) 41B is an absorption type linear polarizing plate. As the absorption type linear polarizing plate, a linear polarizing plate composed of a film polarizer dyed and stretched with polyvinyl alcohol (PVA) and a triacetyl cellulose (TAC) protective layer, a dye-based polarizing plate, a coated-type polarizing plate, and the like can be used. The absorption-type linear polarization plate has a transmission axis and an absorption axis orthogonal to the transmission axis.

As the first linear polarizing plate (back linear polarizing plate) 41A, an absorption type linear polarizing plate can be used as in the case of the front linear polarizing plate 41B. Further, a reflective type linear polarizing plate, or a laminate of an absorptive type linear polarizing plate and a reflective type linear polarizing plate may be used. Examples of the reflective linear polarizing plate include a multilayer reflective polarizing plate (trade name: DBEF) manufactured by 3M Japan, a reflective linear polarizing plate formed by combining a cholesteric liquid crystal film with a lambda/4 plate. The reflection type linear polarizing plate has a reflection axis in a direction perpendicular to the transmission axis, unlike the absorption type linear polarizing plate. Therefore, a part of the light from the backlight BL is reflected by the reflective linear polarizing plate, and is further reflected by the reflection plate 53 included in the backlight BL, and is recycled. The reflection type linear polarizing plate may be included in the backlight BL instead of the back surface linear polarizing plate 41A.

The first phase difference plate 42A and the second phase difference plate 42B may be a single λ/4 plate, or may be a combination of a single λ/4 plate and one or two λ/2 plates, or a combination of a single λ/4 plate and a single negative C plate.

The orientations of the absorption axes of the back linear polarizing plate 41A and the front linear polarizing plate 41B and the orientations of the retardation axes of the first phase difference plate 42A and the second phase difference plate 42B are set to display in a normally black mode. The liquid crystal molecules of the liquid crystal layer 30 are vertically aligned in the black display state, and tilt at a twist angle of 0 ° in the white display state (and the intermediate gradation display state).

The backlight BL is disposed on the back surface side of the back circular polarizing plate 40A. The backlight BL 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 to the liquid crystal panel side, and a reflection plate 53 disposed on the back surface side of the light guide plate 52. The backlight BL may further include a prism sheet and a diffusion sheet disposed on the front surface side (or the back surface side) of the light guide plate 52.

The illustrated liquid crystal display device 100 has a configuration for performing gradation display by the memory liquid crystal. Specifically, as shown in fig. 1, each pixel P of the liquid crystal display device 100 includes a plurality of subpixels Sp. Fig. 1 shows an example in which one pixel P is divided into three subpixels Sp. The subpixel Sp1 of the three subpixels Sp disposed at the upper side in the drawing is referred to as a "first subpixel", and the subpixel Sp2 disposed at the lower side in the drawing is referred to as a "second subpixel". The subpixel Sp3 disposed at the center in the figure is referred to as a "third subpixel".

The transmission region Tr of each pixel P includes a plurality of sub-transmission regions Tra, trb, and Trc separated from one another. The plurality of sub-transmission regions Tra, trb, and Trc include a first sub-transmission region Tra included in the first subpixel Sp1, a second sub-transmission region Trb included in the second subpixel Sp2, and a third sub-transmission region Trc included in the third subpixel Sp 3.

The first and third sub-transmission regions Tra and Trc each include a first contact hole CH1 and a second contact hole CH2. In contrast, the second sub-transmission region Trb does not include the first contact hole CH1 and the second contact hole CH2.

The pixel electrode 11 includes a plurality of sub-pixel electrodes 11a, 11b, and 11c. The plurality of sub-pixel electrodes 11a, 11b, and 11c include: the first subpixel electrode 11a disposed in the first subpixel Sp1, the second subpixel electrode 11b disposed in the second subpixel Sp2, and the third subpixel electrode 11c disposed in the third subpixel Sp 3.

The first subpixel electrode 11a disposed at the upper side in the drawing and the second subpixel electrode 11b disposed at the lower side in the drawing are electrically connected. In the illustrated example, the pixel electrode 11 further includes a connection electrode 11d, and the first sub-pixel electrode 11a and the second sub-pixel electrode 11b are connected by the connection electrode 11 d.

The first subpixel electrode 11a, the second subpixel electrode 11b, and the connection electrode 11d are integrally formed, and have a U-shape (japanese "コ" shape) as a whole. The third sub-pixel electrode 11c is located between the first sub-pixel electrode 11a and the second sub-pixel electrode 11 b. When the first subpixel electrode 11a, the second subpixel electrode 11b, and the connection electrode 11d are collectively referred to as "first electrode segments", and the third subpixel electrode 11c is referred to as "second electrode segments", the area ratio of the first electrode segments to the second electrode segments is, for example, about 2:1.

The first subpixel electrode 11a and the second subpixel electrode 11b are electrically connected to a common one of the memory circuits via the first contact hole CH1 and the second contact hole CH2 included in the first subpixel transmissive region Tra. The third subpixel electrode 11c is electrically connected to another memory circuit by the first contact hole CH1 and the second contact hole CH2 included through the third subpixel transmissive region Trc. That is, two memory circuits are provided for each pixel P.

As shown in fig. 1, the pixel P is divided, and thus 4-gradation display by the area gradation method can be performed as shown in fig. 3. Specifically, as shown in the leftmost part of fig. 3, all three subpixels Sp are set to the black display state, so that black display can be performed as a whole in one pixel P, and as shown in the second part of fig. 3 from the left side, two subpixels Sp are set to the black display state, and one subpixel Sp is set to the white display state, so that dark intermediate gradation display can be performed as a whole in one pixel P. Further, as shown in the third from the left in fig. 3, by setting two subpixels Sp to the white display state and setting one subpixel Sp to the black display state, bright intermediate gradation display can be performed as one pixel P as a whole, and as shown in the rightmost side in fig. 3, white display can be performed as one pixel P as a whole by setting all three subpixels Sp to the white display state.

The three sub-pixel electrodes 11a, 11b, and 11c may be electrically connected to different memory circuits, respectively (that is, three memory circuits may be provided in each pixel P).

As already described, the first interlayer insulating layer 13 has a concave portion (transmission opening groove) TG. Hereinafter, the concave portion TG will be described more specifically.

As shown in fig. 2, the recess TG is defined by a bottom surface bf and an inclined side surface if. When the portion uf of the first interlayer insulating layer 13 on the liquid crystal layer 30 side where the concave portion TG is not formed is referred to as the "upper surface", the inclined side surface if is a portion connecting the upper surface uf and the bottom surface bf. The inclined side surface if is inclined with respect to the substrate surface of the transparent substrate 10 a.

At least a part of the concave portion TG is located in the transmission region Tr. The first contact hole CH1 is formed to overlap a portion of the recess TG. The depth d _TG (height difference between the upper surface uf and the bottom surface bf) of the concave portion TG is 0.5 μm or more. The inclination angle θ of the inclined side face if of the concave portion TG is 25 ° or less.

As described above, the liquid crystal display device 100 of the present embodiment has a two-stage electrode structure in which the reflective layer (reflective electrode) 12 and the pixel electrode 11 are separated by the first interlayer insulating layer 13. Thus, the reflective layer 12 may include not only the first portion 12a located within the pixel P, but also the second portion 12b located between two adjacent pixels P. Therefore, the area between the pixels P can contribute to the reflective display, and therefore the reflective aperture ratio (the proportion of the area contributing to the display of the reflective mode in the display area) is improved, and further improvement of the reflectance can be achieved. Therefore, brighter display can be performed in the reflection mode. Further, since the uneven surface structure of the reflective layer 12 is planarized by the first interlayer insulating layer 13 formed under the pixel electrode 11, alignment disorder due to the uneven surface structure of the reflective layer 12 is not generated, and alignment with high in-plane uniformity is obtained.

In the liquid crystal display device 100 of the present embodiment, since the region between the pixels P contributes to the display in the reflection mode, the counter substrate 20 preferably does not have a black matrix between any two pixels P adjacent to each other among the plurality of pixels P.

In the liquid crystal display device 100 of the present embodiment, the first interlayer insulating layer 13 has the concave portion TG, and a multi-gap structure (a structure in which the transmissive cell gap dt is larger than the reflective cell gap dr) is realized. Light used in display in the transmissive mode passes through the liquid crystal layer 30 only once, while light used in display in the reflective mode passes through the liquid crystal layer 30 twice. Therefore, as in the present embodiment, by making the cell gap dt of the transmission region Tr larger than the cell gap dr of the reflection region Rf, the retardation of the liquid crystal layer 30 with respect to light used for display in the transmission mode can be increased, and a preferable voltage-luminance characteristic (capable of realizing brighter display) can be obtained for the transmission region Tr.

According to the studies of the present inventors, it is found that in a semi-transmissive LCD having a multi-gap structure, a cell gap varies from pixel to pixel, and a display failure may occur due to this. In addition, the reason why the cell gap becomes uneven is also known to be that: in the application of the alignment film material for forming the first alignment film 15, the thickness of the application varies from pixel to pixel due to the shape, size, etc. of the recess TG of the first interlayer insulating layer 13, and thus the film thickness of the first alignment film 15 is non-uniform. In contrast, in the liquid crystal display device 100 of the present embodiment, by setting the inclination angle θ of the inclined side surface if of the concave portion TG to 25 ° or less, as will be described below with reference to the verification result, the occurrence of the display failure as described above can be suppressed. Further, from the viewpoint of ensuring the efficiency of the transmission mode required for the aesthetic appearance, the depth d _TG of the concave portion TG is preferably 0.5 μm or more.

Specifically, the verification is performed as follows.

First, a liquid crystal display panel ("panel # 1") in which the inclination angle of the inclined side surface of the concave portion is relatively large and a liquid crystal display panel ("panel # 2") in which the inclination angle is relatively small are produced. After the appearance inspection of the panels #1 and #2, unevenness was observed in the panel #1, whereas no unevenness was observed in the panel # 2.

For the TFT substrate of panel #1, cross-sectional SEM images of two pixels (pixel 1A, pixel 1B) having a difference in display state were obtained. Further, regarding the TFT substrate of the panel #2, cross-sectional SEM images of any two pixels (pixel 2A, pixel 2B) were obtained. Then, the inclination angle of the inclined side face of the concave portion, the depth of the concave portion, the thickness of the first alignment film, and the transmission cell gap are calculated from these SEM images, and the difference in transmission mode efficiency of the two pixels in the panel (pixel 1A and pixel 1B in panel #1, pixel 2A and pixel 2B in panel # 2) is calculated. The results are shown in table 1.

TABLE 1

As is clear from table 1, in the panel #1, the depth of the concave portion was 2.03 μm, and the inclination angle of the inclined side surface was 26 °. In contrast, in the panel #2, the depth of the concave portion was 1.59 μm, and the inclination angle of the inclined side surface was 18 °. The difference in transmission mode efficiency was 3.1% in panel #1 and 0.5% in panel # 2. The concave portion of the panel #1 is deep and the transmission cell gap is large compared to the panel #2, and thus the transmission mode efficiency itself is high. However, it is assumed that in the panel #1, since the concave portion is deep, the inclination angle of the inclined side surface increases, and the thickness of the alignment film becomes uneven.

From the results shown in table 1, the deviation of the thickness of the first alignment film (the thickness on the bottom surface of the concave portion) and the transmission cell gap determined from this were calculated by simulation for the two pixels A, B in the range of the tilt angle of 4 ° to 30 °. In the calculation, as shown in fig. 4, the depth d _TG of the concave portion TG, the thickness t2 of the first alignment film 15 on the bottom surface bf, and the transmission cell gap dt were calculated on the basis of setting the reflection cell gap dr to 2 μm, the width W _TG of the concave portion TG to 20 μm, and the thickness t1 of the first alignment film 15 on the upper surface uf and the inclined side surface if to 0.13 μm. The transmission mode efficiency was calculated by simulation based on measurement data on the trial-produced panel A, B and calculation data of orientation simulation software (LCDMASTER manufactured by Siteck corporation) (relationship between cell gap and mode efficiency shown in fig. 5). The calculation results are shown in tables 2 to 5.

TABLE 2

TABLE 3

TABLE 4

TABLE 5

The "average transmission cell gap" shown in tables 2 and 3 is a value obtained by averaging the thickness of the liquid crystal layer 30 in the transmission region Tr, including the thickness of the region corresponding to the inclined side face if of the concave portion TG. In addition, in tables 4 and 5, the difference in transmission mode efficiency in the two pixels a and B and the display quality determined based thereon are also shown. The display quality is very good ("O") when the difference in transmission mode efficiency is 2.0% or less, good ("Δ") when it is more than 2.0% and 3.0% or less, and poor ("×") when it is more than 3.0%.

As is clear from tables 2 to 5, the smaller the inclination angle θ is, the smaller the variation in the thickness of the first alignment film 15 is, and the display quality tends to be improved. From the viewpoint of display quality, the tilt angle θ is preferably 25 ° or less, and more preferably 22 ° or less. As described above, the depth d _TG of the concave portion TG is preferably 0.5 μm or more from the viewpoint of securing the transmission mode efficiency required for the aesthetic appearance.

Next, based on the results shown in tables 2 to 5, the transmission mode efficiency was calculated by simulation when the transmission cell gap dt was increased up to the theoretical limit in a state where the tilt angle θ was fixed. At the time of calculation, the thickness of the first alignment film 15 (thickness t2 on the bottom surface bf) entirely depends on the inclination angle θ of the inclined side face if. The calculation results are shown in tables 6 to 9.

TABLE 6

TABLE 7

TABLE 8

TABLE 9

As can be seen from tables 6 to 9, the transmission mode efficiency is improved by increasing the transmission cell gap dt.

Next, based on the results shown in tables 2 to 5, the transmission mode efficiency was calculated by simulation when the tilt angle θ was reduced to the limit with the depth d _TG of the concave portion TG fixed. At the time of calculation, the thickness of the first alignment film 15 (thickness t2 on the bottom surface bf) entirely depends on the inclination angle θ of the inclined side face if. The calculation results are shown in tables 10 to 13.

TABLE 10

TABLE 11

TABLE 12

TABLE 13

As is clear from tables 10 to 13, by reducing the inclination angle θ of the inclined side face if of the concave portion TG, the variation in the thickness of the first alignment film 15 can be suppressed, and the display quality (the difference in the transmission mode efficiency is reduced) can be improved.

From these results, it is found that by reducing the inclination angle θ of the inclined side face if of the concave portion TG (specifically, 25 ° or less, preferably 22 ° or less) while maintaining the relatively large transmission cell gap dt, it is possible to achieve both a sufficiently high transmission mode efficiency and good display quality.

Here, an example of a method of appropriately forming the inclined side surface if having the relatively small inclination angle θ will be described.

When a photosensitive resin material is used as the material of the first interlayer insulating layer 13, a recess TG can be formed by first applying the photosensitive resin material to the reflective layer 12, then exposing the photosensitive resin material to light (for example, ultraviolet light) through a photomask, and then developing the exposed photosensitive resin material. Here, a case where a positive photosensitive resin material is used will be described as an example.

Fig. 6 and 6B show an example of a photomask used when forming the concave portion TG. In fig. 6 and 6B, the outer edge of one sub-transmission region is shown with a dotted line.

The photomask 70A shown in fig. 6A has a light-shielding region 71 and a light-transmitting region 72. In the photomask 70A, the light-transmitting region 72 includes island-shaped portions 72a arranged corresponding to the respective sub-transmitting regions, and a concave portion TG corresponding to one sub-transmitting region is formed corresponding to one (single) island-shaped portion 72 a.

The photomask 70B shown in fig. 6B also has a light-shielding region 71 and a light-transmitting region 72. However, in the photomask 70B, the light-transmitting region 72 includes island-shaped portions 72a and a plurality of slit portions 72B arranged in correspondence with the respective sub-transmission regions, and concave portions TG corresponding to one sub-transmission region are formed in correspondence with one island-shaped portion 72a and a plurality of slit portions 72B. The slit portions 72b are located outside the island portions 72a and are arranged near the outer edge of the sub-transmissive region. The width of the slit portion 72b is equal to or smaller than the resolution of the exposure machine (for example, 1.0 μm to 2.0 μm).

Fig. 7A and 7B are diagrams schematically showing the exposure of the photosensitive resin material 13' using the photomasks 70A and 70B, respectively. In fig. 7 and 7B, the cross-sectional shape of the recess TG formed after development is shown by a broken line.

As can be seen from a comparison of fig. 7A and 7B, when exposure is performed using the photomask 70B, an inclined side surface if is formed at a smaller (i.e., gentle) inclination angle θ than in the case of exposure using the photomask 70A. This is because, when the photomask 70B including the slit portion 72B is used for the light-transmitting region 72, the region that becomes the inclined side face if is exposed to the intermediate light amount.

Here, the results of verifying the effect of including the slit portion in the light-transmitting region of the photomask will be described.

As shown in fig. 8A, a photomask 70B having a slit portion 72B with a width of 1.5 μm arranged on one side of the island portion 72a with an angle of 4 μm and having no slit portion 72B arranged on the other side was prepared, and a photosensitive resin material 83' was exposed using the photomask 70B. As shown in fig. 8B, in the recess TG of the insulating layer 83 obtained by development thereafter, the inclination angle θ of the inclined side face if is 38 ° on the side corresponding to the slit portion 72B, and 49 ° on the side not corresponding to the slit portion 72B. In this way, it was confirmed that by including the slit portion in the light transmitting region of the photomask, the inclined side face if having the relatively small inclination angle θ can be appropriately formed.

Fig. 9 shows another example of the configuration of the liquid crystal display device 100 according to the embodiment of the present invention. In the example shown in fig. 2, a part of the bottom surface bf and the inclined side surface if of the concave portion TG are located in the reflection region Rf. In contrast, in the example shown in fig. 9, the bottom surface bf and the inclined side surface if of the concave portion TG are located in the transmission region Tr, and are not included in the reflection region Rf. When a part of the bottom surface bf of the concave portion TG and the inclined side surface if are located in the reflection region Rf, there is a possibility that yellow displacement of the reflection whiteness occurs due to the increase of the effective reflection cell gap dr. As shown in the example shown in fig. 9, since the bottom surface bf and the inclined side surface if of the concave portion TG are not included in the reflection region Rf, the yellow shift of the reflection whiteness can be suppressed.

Still another example of the structure of the liquid crystal display device 100 will be described with reference to fig. 10, 11, and 12. Fig. 10, 11, and 12 are sectional views schematically showing the liquid crystal display device 100, and show areas corresponding to the red pixel P _R, the green pixel P _G, and the blue pixel P _B. In fig. 10, 11 and 12, the structure of the TFT substrate 10 is simplified.

As shown in fig. 10, 11 and 12, the color filter layer 22 of the liquid crystal display device 100 includes a red color filter 22R disposed at the red pixel P _R, a green color filter 22G disposed at the green pixel P _G, and a blue color filter 22B disposed at the blue pixel P _B. The thickness t _B of the blue filter 22B is greater than the thickness t _R of the red filter 22R and the thickness t _G of the green filter 22G, respectively. Therefore, the reflective cell gap dr _B of the blue pixel P _B is smaller than the reflective cell gap dr _R of the red pixel P _R and the reflective cell gap dr _G of the green pixel P _G, respectively.

Specifically, in the example shown in fig. 10, the reflection cell gap dr _R of the red pixel P _R is the same as the reflection cell gap dr _G of the green pixel P _G, and the reflection cell gap dr _B of the blue pixel P _B is smaller than them (i.e., dr _R＝dr_G＞dr_B). In addition, in the example shown in fig. 11, the reflective cell gap dr _R of the red pixel P _R is smaller than the reflective cell gap dr _G of the green pixel P _G, and the reflective cell gap dr _B of the blue pixel P _B is smaller than the reflective cell gap dr _R (i.e., dr _G＞dr_R＞dr_B) of the red pixel P _R. In the example shown in fig. 12, the reflective cell gap dr _G of the green pixel P _G is smaller than the reflective cell gap dr _R of the red pixel P _R, and the reflective cell gap dr _B of the blue pixel P _B is smaller than the reflective cell gap dr _G of the green pixel P _G (i.e., dr _R＞dr_G＞dr_B).

As described above, in the examples shown in fig. 10, 11 and 12, the reflection cell gap dr _B of the blue pixel P _B is smaller than the reflection cell gap dr _R of the red pixel P _R and the reflection cell gap dr _G of the green pixel P _G, respectively. In the case of using the VA-ECB mode as the display mode, by setting the reflective cell gap dr _R of the red pixel P _R, the reflective cell gap dr _G of the green pixel P _G, and the reflective cell gap dr _B of the blue pixel P _B in this manner, it is possible to suppress a change in reflectance due to a change in cell gap.

The structure of the pixel electrode 11 is not limited to the example shown in fig. 1. Fig. 13 shows another example of the structure of the pixel electrode 11.

The example shown in fig. 13 differs from the example shown in fig. 1 in the following points: the first subpixel Sp1 is located at the center of the figure, and the third subpixel Sp3 is located at the upper side of the figure. That is, in the example shown in fig. 1, the third subpixel Sp3 is located between the first subpixel Sp1 and the second subpixel Sp2, whereas in the example shown in fig. 13, the first subpixel Sp1 and the second subpixel Sp2 are adjacent without the third subpixel Sp 3.

In the example shown in fig. 13, the first sub-pixel electrode 11a and the second sub-pixel electrode 11b adjacent to each other are continuously formed. When the first subpixel electrode 11a and the second subpixel electrode 11b are collectively referred to as "first electrode segments" and the third subpixel electrode 11c is referred to as "second electrode segments", the first electrode segments are rectangular with a larger aspect ratio than the second electrode segments. The area ratio of the first electrode segment to the second electrode segment is, for example, about 2:1.

In the example shown in fig. 13, as shown in fig. 14, 4-gradation display by the area gradation method can be performed. Specifically, as shown in the leftmost part of fig. 14, all three subpixels Sp are set to the black display state, so that black display can be performed as a whole in one pixel P, and as shown in the second part of fig. 14 from the left side, two subpixels Sp are set to the black display state, and one subpixel Sp is set to the white display state, so that dark intermediate gradation display can be performed as a whole in one pixel P. Further, as shown in the third from the left in fig. 14, by setting two subpixels Sp to the white display state and setting one subpixel Sp to the black display state, bright intermediate gradation display can be performed as one pixel P as a whole, and as shown in the rightmost side in fig. 14, white display can be performed as one pixel P as a whole by setting all three subpixels Sp to the white display state.

However, in the example shown in fig. 13, the clarity of the display of characters and the like may be slightly lowered. The reason for this will be described below.

In the case of displaying a character, in order to express the smoothness of the character, only a part of the subpixels Sp may be turned on in the pixels P at the end of the displayed character (in a white display state). In the case of the configuration shown in fig. 13, when only the first subpixel Sp1 and the second subpixel Sp2 are turned on, when only the third subpixel Sp3 is turned on, and when all the subpixels Sp are turned on, the positions of the center of gravity (the geometric center of the area in the white display state) of the luminance are different, and thus, the luminance varies. This variation in brightness causes a decrease in the sharpness of the display of the character or the specific pattern.

In contrast, as shown in the example of fig. 1, since the first electrode segment has a U-shape sandwiching the second electrode segment, the difference in the position of the center of gravity (the geometric center of the area in the white display state) of the luminance can be reduced (for example, the center of gravity position is made substantially the same) when only the first subpixel Sp1 and the second subpixel Sp2 are turned on, only the third subpixel Sp3 is turned on, and all the subpixels Sp are turned on. Therefore, the variation in brightness can be reduced, and the definition of the display of the character or the specific pattern can be improved (more natural display can be realized).

Fig. 15 shows an example of actual character display in the case where the electrode structure shown in fig. 1 is used, and fig. 15 shows an example of actual character display in the case where the electrode structure shown in fig. 13 is used. In the display example shown in fig. 15A, it is known that the character display is smoother than that in the display example shown in fig. 15B.

The change in the shape of the first electrode segment es1 and the second electrode segment es2 is described with reference to fig. 16A and 16B.

In either one of the pixel electrode 11 shown in fig. 16A and the pixel electrode 11 shown in fig. 16B, the first electrode segment es1 is U-shaped sandwiching the second electrode segment es 2. However, as will be described later, the gap SB between the first electrode segment es1 and the second electrode segment es2 (hereinafter referred to as "segment boundary") has a curved shape in the example shown in fig. 16B, and does not include a curved portion in the example shown in fig. 16A.

In the pixel electrode 11 shown in fig. 16A, the portion po1 of the predetermined segment boundary SB in the outer edge of the first electrode segment es1 and the portion po2 of the predetermined segment boundary in the outer edge of the second electrode segment es2 are each constituted by 3 straight portions, and do not include a curved portion. Therefore, the segment boundary SB also does not include a curved portion.

In contrast, in the pixel electrode 11 shown in fig. 16B, the portion po1 of the predetermined segment boundary SB in the outer edge of the first electrode segment es1 and the portion po2 of the predetermined segment boundary in the outer edge of the second electrode segment es2 are arc-shaped, respectively, and the second electrode segment es2 is half-moon-shaped. Thus, the segment boundary SB has a curved shape.

As shown in fig. 16B, if the segment boundary SB has a curved shape, the area of the segment boundary SB (so-called non-lit region) can be reduced and the aperture ratio can be increased as compared with the case where the segment boundary SB does not include a curved portion as shown in fig. 16A. The area of the reflection region Rf (hatched region in fig. 16A and 16B) was calculated and compared in the example shown in fig. 16A and the example shown in fig. 16B on the assumption of a certain pixel size, and as a result, the former was about 3512 μm ² and the latter was about 3547 μm ². That is, in the example shown in fig. 16B, the area of the reflection region Rf is increased by 1.01 times as compared with the example shown in fig. 16A.

The plurality of pixels P of the liquid crystal display device 100 may constitute a plurality of color display pixels. Each color display pixel has three or more pixels P which exhibit mutually different colors. For example, one color display pixel is constituted by the red pixel P _R, the green pixel P _G, and the blue pixel P _B shown in fig. 1.

The embodiment of the present invention is applied to, for example, a liquid crystal display device having a resolution of 180ppi or more, a size of each color display pixel of 140 μm×140 μm or less, and a size of the transmission region Tr (the size of each sub-transmission region when the transmission region Tr is divided into a plurality of sub-transmission regions) of 30 μm×30 μm or less.

In the above description, the configuration in which each pixel P is divided into the plurality of subpixels Sp has been described, but each pixel P may not be divided into the plurality of subpixels Sp.

Industrial applicability

According to the embodiment of the present invention, a semi-transmissive liquid crystal display device in which occurrence of display failure due to cell gap unevenness is suppressed can be provided. The semi-transmissive liquid crystal display device according to the embodiment of the present invention is preferably used as a display device for a smart watch or a digital signage for outdoor advertising.

Description of the reference numerals

10 TFT substrate

10A, 20a transparent substrate

11. Pixel electrode

11A first sub-pixel electrode

11B second sub-pixel electrode

11C third sub-pixel electrode

11D connection electrode

12. Reflective layer

First part of the 12a reflective layer

12B second portion of the reflective layer

13. A first interlayer insulating layer

14. Second interlayer insulating layer

15. First alignment film

19. Transparent conductive layer

20. Counter substrate

21. Counter electrode

22. Color filter layer

22R red filter

22G green filter

22B blue filter

25. Second alignment film

30. Liquid crystal layer

40A back circular polarizing plate

40B surface circular polarizing plate

41A back linear polarizing plate

41B surface linear polarizing plate

42A first phase difference plate

42B second phase difference plate

51. Light source

52. Light guide plate

53. Reflecting plate

70A, 70B photomask

71. Shading area

72. Light-transmitting region

72A island

72B slit portion

100. Liquid crystal display device having a light shielding layer

LP liquid crystal display panel

BL backlight

P pixel

P _R red pixel

P _G green pixel

P _B blue pixel

Sp sub-pixel

Sp1 first sub-pixel

Sp2 second sub-pixel

Sp3 third subpixel

Rf reflective region

Tr transmission region

Tra first sub-transmission region

Trb second sub-transmission region

Trc third sub-transmission region

CP contact

Ce1 first contact electrode

Ce2 second contact electrode

Ce3 third contact electrode

CH1 first contact hole

CH2 second contact hole

Recess of TG first interlayer insulating layer (transmission open groove)

Upper surface of uf first interlayer insulating layer

Bottom surface of bf concave portion

Inclined side of if recess

Es1 first electrode segment

Es2 second electrode segment

SB segment boundary

Claims

1. A liquid crystal display device, comprising:

A first substrate;

A second substrate facing the first substrate; and

A liquid crystal layer disposed between the first and second substrates, and

The liquid crystal display device has a plurality of pixels which include a plurality of rows and a plurality of columns and are arranged in a matrix, and is characterized in that,

The first substrate has:

A reflective layer;

The depth of the recess of the interlayer insulating layer is 0.5 μm or more,

2. The liquid crystal display device according to claim 1, wherein,

The inclined side surface of the recess has an inclination angle of 22 DEG or less.

3. The liquid crystal display device according to claim 1 or 2, wherein,

The bottom surface and the inclined side surface of the recess are located in the transmissive region.

4. The liquid crystal display device according to claim 1 or 2, wherein,

The reflective layer has a concave-convex surface structure.

5. The liquid crystal display device according to claim 1 or 2, wherein,

The reflective layer has a substantially planar surface.

6. The liquid crystal display device according to claim 1 or 2, wherein,

The liquid crystal layer is vertically oriented.

7. The liquid crystal display device according to claim 1 or 2, wherein,

The liquid crystal layer is horizontally oriented.

8. The liquid crystal display device according to claim 1 or 2, wherein,

The first substrate also has a back-plate circuit that drives the plurality of pixels,

9. The liquid crystal display device according to claim 1 or 2, wherein,

The transmissive region of each pixel includes a plurality of sub-transmissive regions spaced apart from each other,

The plurality of sub-transmissive regions includes: a first sub-transmission region including a contact hole; and a second sub-transmission region not including the contact hole.

10. The liquid crystal display device according to claim 9, wherein,

Each pixel comprises a plurality of sub-pixels,

The plurality of subpixels includes: a first subpixel including the first sub-transmissive region; a second sub-pixel including the second sub-transmissive region,

The pixel electrode includes a plurality of sub-pixel electrodes,

11. The liquid crystal display device according to claim 10, wherein,

The pixel electrode further comprises a connection electrode connecting the first sub-pixel electrode and the second sub-pixel electrode,

The first sub-pixel electrode, the second sub-pixel electrode and the connecting electrode are U-shaped as a whole.

12. The liquid crystal display device of claim 11, wherein the liquid crystal display device comprises,

The plurality of sub-transmissive regions further comprises a third sub-transmissive region, the third sub-transmissive region comprising the contact hole,

13. The liquid crystal display device of claim 12, wherein the liquid crystal display device comprises,

When the first sub-pixel electrode, the second sub-pixel electrode, and the connection electrode are referred to as a first electrode segment, the third sub-pixel electrode is referred to as a second electrode segment, and a gap between the first electrode segment and the second electrode segment is referred to as a segment boundary, the segment boundary has a curved shape.

14. The liquid crystal display device of claim 13, wherein the liquid crystal display device comprises,

The portion of the outer edge of the first electrode segment defining the segment boundary and the portion of the outer edge of the second electrode segment defining the segment boundary are each arc-shaped.

15. The liquid crystal display device according to claim 1 or 2, wherein,

The first substrate has an alignment film provided in contact with the liquid crystal layer.

16. The liquid crystal display device according to claim 1 or 2, wherein,

The plurality of pixels constitutes a plurality of color display pixels,

Each of the plurality of color display pixels has three or more pixels exhibiting mutually different colors,

The resolution is more than 180ppi,

The size of each color display pixel is 140 μm by 140 μm or less,

The size of the transmission region is 30 μm×30 μm or less.

17. The liquid crystal display device according to claim 1 or 2, wherein,

The thickness of the liquid crystal layer in the reflective region is 2.0 μm or more and 2.5 μm or less,

18. The liquid crystal display device according to claim 1 or 2, wherein,

The plurality of pixels includes a red pixel displaying red, a green pixel displaying green, and a blue pixel displaying blue,

19. The liquid crystal display device of claim 18, wherein the liquid crystal display device comprises,

The second substrate has a color filter layer,

The color filter layer includes a red filter disposed in the red pixel, a green filter disposed in the green pixel, and a blue filter disposed in the blue pixel,

The thickness of the blue filter is respectively larger than that of the red filter and that of the green filter.