JP2005157224A - Liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display that fully stabilizes alignment of liquid crystal with relatively simple constitution, in which a wall structure for alignment control is provided only on a substrate on one side, and that can be manufactured through easier processes than before. <P>SOLUTION: The liquid crystal display includes a first substrate 110a, a second substrate 110b placed to face the first substrate, a liquid crystal layer 120 interposed between the first and second substrates, a first electrode 111 formed on the first substrate, a second electrode 131 formed on the second substrate, an interlayer insulating film 115a placed in between the first electrode and the first substrate, and the wall structure 115b formed integrally with the interlayer insulating film. The liquid crystal display has a plurality of pixels each including the first electrode, the second electrode and the liquid crystal layer interposed between the first and second electrodes. A light-shielding region surrounds each of the plurality of pixels, and the wall structure is placed regularly in the shading region. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device suitably used for a personal digital assistant (for example, PDA), a mobile phone, an in-vehicle liquid crystal display, a digital camera, a personal computer, an amusement device, a television, and the like.

  In recent years, liquid crystal display devices have been widely used for information devices such as notebook personal computers, mobile phones, electronic notebooks, or camera-integrated VTRs equipped with a liquid crystal monitor, taking advantage of their thinness and low power consumption. ing.

  As a display mode capable of realizing a high contrast and a wide viewing angle, a vertical alignment mode using a vertical alignment type liquid crystal layer has attracted attention. The vertical alignment type liquid crystal layer is generally formed using a vertical alignment film and a liquid crystal material having negative dielectric anisotropy.

  For example, Patent Document 1 discloses that an oblique electric field is generated around an opening provided in a counter electrode facing a pixel electrode via a liquid crystal layer, and liquid crystal around the liquid crystal molecules in a vertically aligned state in the opening. A liquid crystal display device in which viewing angle characteristics are improved by tilting molecules is disclosed.

  However, in the configuration described in Patent Document 1, it is difficult to form an oblique electric field in the entire region in the pixel. As a result, a region in which the response of the liquid crystal molecules to the voltage is delayed occurs in the pixel, and an afterimage phenomenon occurs. The problem of appearing arises.

  In order to solve this problem, Patent Document 2 discloses a liquid crystal display device having a plurality of liquid crystal domains exhibiting a radially inclined alignment in a pixel by providing openings regularly arranged in the pixel electrode or the counter electrode. doing.

  Furthermore, Patent Document 3 discloses a technique for stabilizing the alignment state of a liquid crystal domain having an inclined radial alignment that appears around a convex portion by providing a plurality of convex portions regularly in a pixel. . Further, this document discloses that the display characteristics can be improved by regulating the alignment of liquid crystal molecules using an oblique electric field by an opening provided in the electrode, together with the alignment regulating force by the convex part.

  On the other hand, in recent years, liquid crystal display devices capable of high-quality display both outdoors and indoors have been proposed (for example, Patent Document 4 and Patent Document 5). This liquid crystal display device is referred to as a transflective liquid crystal display device, and has a reflective region in a pixel for displaying in a reflective mode and a transmissive region for displaying in a transmissive mode.

  The transflective liquid crystal display devices currently on the market use the ECB mode, the TN mode, and the like. However, in Patent Document 3, the vertical alignment mode is not limited to the transmissive liquid crystal display device but also the transflective liquid crystal. A configuration applied to a display device is also disclosed. Further, in Patent Document 6, in a semi-transmissive liquid crystal display device having a vertical alignment type liquid crystal layer, an insulating layer provided to make the thickness of the liquid crystal layer in the transmissive region twice the thickness of the liquid crystal layer in the reflective region. A technique for controlling the alignment (multiaxial alignment) of liquid crystals by the formed recesses is disclosed. A configuration is disclosed in which the recess is formed in, for example, a regular octagon, and a projection (projection) or a slit (electrode opening) is formed at a position facing the recess via the liquid crystal layer (for example, FIG. 4 and FIG. 16).

Further, in order to improve display quality in the reflection mode, a technique for forming a diffuse reflection layer having excellent diffuse reflection characteristics has been studied. For example, Patent Document 7 discloses a technique for obtaining good diffuse reflection characteristics by forming fine uneven shapes randomly arranged on the surface of the reflective electrode through a photolithography process using a two-layer photosensitive resin film. Is disclosed. Further, in Patent Document 8, for the purpose of simplifying the manufacturing process, a single layer of photosensitive resin is used to expose and develop a contact hole and a photomask for forming fine irregularities. Thus, a technique for forming a reflective electrode having a fine uneven shape is disclosed.
JP-A-6-301036 JP 2000-47217 A JP 2003-167253 A Japanese Patent No. 29555277 US Pat. No. 6,195,140 JP 2002-350853 A JP-A-6-75238 Japanese Patent Laid-Open No. 9-90426

  In the technique disclosed in Patent Document 2 or Patent Document 3, a plurality of liquid crystal domains are formed by providing convex portions or openings in a pixel (that is, divided into pixels), and the alignment regulation force on liquid crystal molecules is strengthened. However, according to the study of the present inventors, in order to obtain a sufficient alignment regulating force, alignment regulating structures such as convex portions and openings are formed on both sides of the liquid crystal layer (the liquid crystal layer side of a pair of substrates facing each other). There is a problem that the manufacturing process becomes complicated. In addition, the effective aperture ratio of the pixel provided with the alignment regulating structure in the pixel may be decreased, or the contrast ratio may be decreased due to light leakage from the periphery of the convex portion in the pixel. In the case where the alignment regulating structure is provided on both the substrates, since it is affected by the alignment margin of the substrates, the effective aperture ratio and / or the contrast ratio are further reduced.

  Further, in the technique disclosed in Patent Document 6, it is necessary to arrange a convex part or an electrode opening on the side opposite to the concave part provided in order to control the multiaxial orientation. Occur.

  In addition, for example, when the reflective electrode is formed using the method described in Patent Document 7 or 8 in order to improve the display quality of the reflective mode of the transflective liquid crystal display device, the manufacturing process becomes complicated. There is. That is, it is necessary to form not only convex portions for regulating the orientation but also fine irregularities for improving the diffuse reflection characteristics, leading to an increase in the cost of the liquid crystal display device.

  The present invention has been made in view of the above points, and its purpose is to provide a relatively simple configuration in which a wall structure for alignment control is provided only on a substrate on one side, and sufficient alignment of liquid crystals. An object of the present invention is to provide a liquid crystal display device that can be stabilized and manufactured by a simpler process than before and a manufacturing method thereof.

  The liquid crystal display device of the present invention includes a first substrate, a second substrate provided to face the first substrate, a liquid crystal layer provided between the first substrate and the second substrate, A first electrode formed on the first substrate; a second electrode formed on the second substrate; an interlayer insulating film provided between the first electrode and the first substrate; and the interlayer A wall structure integrally formed with the insulating film, each of which includes the first electrode, the second electrode, and the liquid crystal layer provided between the first electrode and the second electrode; A plurality of pixels including a light shielding region around each of the plurality of pixels, and the wall structure is regularly arranged in the light shielding region.

  In one embodiment, a plurality of switching elements electrically connected to the first electrode are further provided on the first substrate, and at least a part of the switching elements is covered with the interlayer insulating film.

  In one embodiment, the first electrode included in each of the plurality of pixels includes a transparent electrode and a reflective electrode.

  In one embodiment, the wall structure has an inclined side surface, and the first electrode extends to the side surface.

  In one embodiment, the liquid crystal layer is a vertical alignment type liquid crystal layer and forms at least two liquid crystal domains including liquid crystal molecules aligned in different directions when at least a predetermined voltage is applied.

  In one embodiment, the first electrode and / or the second electrode has a plurality of openings or notches formed at predetermined positions.

  In one embodiment, the first electrode and / or the second electrode has at least two openings and at least one notch formed at predetermined positions.

  In one embodiment, the plurality of openings or notches are formed only in the first electrode.

  In one embodiment, the liquid crystal layer is a vertical alignment type liquid crystal layer, and forms at least two liquid crystal domains each exhibiting axial symmetry alignment when at least a predetermined voltage is applied. The central axis of each axially symmetric orientation is formed in or near the plurality of openings.

  In one embodiment, the wall structure has walls separated by a wall gap.

  In one embodiment, the length of the wall gap existing around one pixel is 40% or less with respect to the length around the pixel.

  In one embodiment, a support that defines the thickness of the liquid crystal layer is regularly arranged in the light shielding region.

  In one embodiment, the wall structure has walls separated by a wall gap, and the support is disposed in the wall gap.

In one embodiment, the diameter of the support is WL (μm), the number N of the support is arranged per regular unit (0.12 mm ² ), and the pitch in the long side direction of the plurality of pixels is PL (Μm), the arrangement density D defined by WL × N / PL satisfies the relationship of 0.01 ≦ D ≦ 0.3.

  In one embodiment, the liquid crystal layer is a vertical alignment type liquid crystal layer, and forms at least one liquid crystal domain each exhibiting axial symmetry alignment when at least a predetermined voltage is applied, and the wall structure is inclined. The cross-sectional shape of the wall structure and the interlayer insulating film in a plane perpendicular to the first substrate has a side surface and a region where a central axis of an axially symmetric orientation of the at least one liquid crystal domain is formed. It is a continuous shape.

  In one embodiment, the wall structure has inclined side surfaces, and an inclination angle of the inclined side surfaces with respect to the surface of the first substrate is 45 ° or less.

  In one embodiment, the first substrate and / or the second substrate and the pair of polarizing plates have a pair of polarizing plates disposed so as to face each other with the first substrate and the second substrate interposed therebetween. And at least one biaxial optically anisotropic medium layer.

  In one embodiment, the liquid crystal display device further includes a pair of polarizing plates disposed so as to face each other with the first substrate and the second substrate interposed therebetween, and the first substrate and / or the second substrate and the pair of polarizations It further has at least one uniaxial optically anisotropic medium layer between the plates.

  The method of manufacturing a liquid crystal display device according to the present invention includes a first substrate, a second substrate provided to face the first substrate, and a liquid crystal provided between the first substrate and the second substrate. A first electrode formed on the first substrate; a circuit element electrically connected to the first electrode; a second electrode formed on the second substrate; and the first electrode; An interlayer insulating film provided between the first substrate and a wall structure formed integrally with the interlayer insulating film, each of which includes the first electrode, the second electrode, A plurality of pixels including the liquid crystal layer provided between the first electrode and the second electrode; a light-shielding region around the plurality of pixels; and the wall structure regularly arranged in the light-shielding region A method for manufacturing a liquid crystal display device disposed on a substrate, comprising: forming a circuit element on a first substrate; A step of forming a positive photosensitive resin film covering the substrate, a step of exposing the photosensitive resin film, forming a predetermined region with different exposure amounts, and the exposed photosensitive resin film Developing an interlayer insulating film having a contact hole exposing a part of the circuit element and integrally formed with the wall structure, and forming a first electrode on the interlayer insulating film And the step of performing.

  In one embodiment, the step of forming the interlayer insulating layer includes a step of forming a first region having a substantially flat surface and a second region having a concavo-convex shape, and forming the first electrode. The step of forming includes a step of forming a transparent electrode on the interlayer insulating film in the first region and a step of forming a reflective electrode on the interlayer insulating film in the second region.

  In one embodiment, in the exposure step, a first photomask is used to form a region serving as the wall structure and other regions, and a second photomask is formed in the other regions. And a second exposure step of forming the first region and the second region.

  In one embodiment, the step of forming the first electrode and / or the second electrode includes a step of forming a conductive film and a step of patterning the conductive film. The step of patterning includes the step of forming the first electrode. Including a step of forming a plurality of openings or notches at predetermined positions of one electrode and / or the second electrode.

  In the liquid crystal display device of the present invention, a wall structure is provided on the liquid crystal layer side of a first substrate on which a first electrode (for example, a pixel electrode) is formed. It is formed integrally with an interlayer insulating film provided between the electrodes. The direction in which the liquid crystal molecules are tilted by the electric field is defined by the anchoring action (alignment regulating force) on the inclined side surface of the wall structure, and as a result, when at least a predetermined voltage (voltage above the threshold) is applied, Thus, at least one liquid crystal domain including liquid crystal molecules having different alignment directions is stably formed in a region substantially surrounded by. Accordingly, the orientation of the liquid crystal molecules can be sufficiently stabilized with a simpler structure than before, and a display quality equal to or higher than that of the conventional one can be obtained. Furthermore, since the wall structure is formed integrally with the interlayer insulating film, it can be manufactured by a simpler process than before.

  Furthermore, when the opening or notch is provided in the first electrode and / or the second electrode, the orientation of the liquid crystal molecules can be further stabilized by the influence of an oblique electric field generated around the opening or notch. As the liquid crystal layer, a vertical alignment type liquid crystal layer can be preferably used, and a stable axially symmetric alignment domain can be formed by a wall structure (and an opening or a notch). Note that at least one liquid crystal domain may be formed in each pixel, but two or more liquid crystal domains may be formed depending on the size and shape of the pixel. For a typical rectangular pixel, It is preferable to form two or more liquid crystal domains.

  The opening has an effect of fixing and stabilizing the position of the central axis of the axially symmetric alignment domain. The opening may be provided in one of the first electrode and the second electrode, but providing the opening in both the first electrode and the second electrode can increase the effect of fixing and stabilizing the position of the central axis. it can. The openings provided in the first electrode and the second electrode are preferably provided at positions that overlap each other when viewed from the normal direction of the substrate. On the other hand, the notch is preferably provided only in the first electrode. In addition, the openings and notches formed in the electrodes can be formed in the process of patterning each electrode, unlike the structural orientation regulation structure such as the wall structure and the convex part, so that the manufacturing process increases. There is nothing. According to the present invention, a stable axially symmetric alignment domain can be formed without providing an alignment regulating structure such as a wall structure or a convex portion on the second substrate.

  A liquid crystal display device according to an embodiment of the present invention includes a first substrate (for example, a TFT side glass substrate), a second substrate (for example, a color filter side glass substrate) provided to face the first substrate, and these substrates. A liquid crystal layer (for example, a vertical alignment type liquid crystal layer) provided between the first substrate, a first electrode (for example, a pixel electrode) formed on the first substrate, and a second electrode (for example, a counter electrode) formed on the second substrate. ), An interlayer insulating film provided between the first electrode and the first substrate, and a wall structure formed integrally with the interlayer insulating film. Each of the plurality of pixels included in the liquid crystal display device includes a first electrode, a second electrode, and a liquid crystal layer provided between the first electrode and the second electrode. A light shielding region is provided, and the wall structures are regularly arranged in the light shielding region. The light shielding region is defined by, for example, a gate signal wiring or a source signal wiring connected to a switching element (for example, TFT) provided on the first substrate.

  The present invention can realize a liquid crystal display device capable of displaying with a wide viewing angle and a high contrast ratio, particularly when a vertical alignment type liquid crystal layer is used and a plurality of axially symmetric alignment domains are formed in each pixel. Therefore, in the following, an embodiment of the present invention will be described taking a liquid crystal display device using a vertical alignment type liquid crystal layer (so-called VA mode liquid crystal display device) as an example. However, the present invention is not limited to this, and at least a predetermined voltage is described. Can be applied to a liquid crystal display device in which at least one liquid crystal domain including liquid crystal molecules aligned in different directions is formed in a pixel. From the viewpoint of viewing angle characteristics, the liquid crystal molecules preferably have liquid crystal domains having four or more alignment directions, and an axially symmetric alignment domain is exemplified below.

  In the following embodiments, transmissive and transflective liquid crystal display devices are exemplified, but the present invention can be applied to reflective display devices.

  The configuration of the liquid crystal display device according to the embodiment of the present invention will be specifically described below with reference to the drawings.

(Transmission type liquid crystal display)
First, the configuration of a transmissive liquid crystal display device 100 according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a diagram schematically showing the configuration of one pixel of the transmissive liquid crystal display device 100, (a) is a plan view, and (b) is 1B-1B ′ in FIG. 1 (a). It is sectional drawing along a line.

  The liquid crystal display device 100 includes a transparent substrate (for example, a glass substrate) 110a, a transparent substrate 110b provided to face the transparent substrate 110a, and a vertical alignment type liquid crystal layer provided between the transparent substrates 110a and 110b. 120. A vertical alignment film (not shown) is provided on the surfaces of the substrates 110a and 110b in contact with the liquid crystal layer 120. When no voltage is applied, the liquid crystal molecules of the liquid crystal layer 120 are substantially perpendicular to the surface of the vertical alignment film. Oriented. The liquid crystal layer 120 includes a nematic liquid crystal material having negative dielectric anisotropy, and further includes a chiral agent as necessary.

  The liquid crystal display device 100 includes a pixel electrode 111 formed on the transparent substrate 110a and a counter electrode 131 formed on the transparent substrate 110b, and a liquid crystal provided between the pixel electrode 111 and the counter electrode 131. Layer 120 defines the pixel. Here, both the pixel electrode 111 and the counter electrode 131 are formed of a transparent conductive layer (for example, an ITO layer). Typically, on the liquid crystal layer 120 side of the transparent substrate 110b, a color filter 130 provided corresponding to the pixel (a plurality of color filters may be collectively referred to as the color filter layer 130), and A black matrix (light-shielding layer) 132 provided between adjacent color filters 130 is formed, and a counter electrode 131 is formed thereon. The color filter layer 130 is formed on the counter electrode 131 (the liquid crystal layer 120 side). Alternatively, the black matrix 132 may be formed.

  The liquid crystal display device 100 has a light shielding region around each pixel, and has a wall structure 115b on a transparent substrate 110a in the light shielding region. The wall structure 115b is an interlayer insulating film formed so as to cover circuit elements (including not only active elements such as switching elements but also wiring and electrodes: not shown here) formed on the transparent substrate 110a. 115a is integrally formed. For example, as will be described later, when an interlayer insulating film is provided in a transmissive liquid crystal display device having a TFT as a circuit element, the pixel electrode can be partially overlapped with the gate signal wiring and / or the source signal wiring. , The aperture ratio can be improved.

  Here, the light shielding region is shielded by, for example, a TFT, a gate signal wiring, a source signal wiring, or a black matrix formed on the transparent substrate 110b, which is formed in the peripheral region of the pixel electrode 111 on the transparent substrate 110a. This area does not contribute to display. Therefore, the wall structure 115b formed in the light shielding region does not adversely affect the display.

  The wall structure 115b illustrated here is provided as a continuous wall so as to surround the pixels, but is not limited thereto, and may be divided into a plurality of walls. Since the wall structure 115b acts to define a boundary formed in the vicinity of the extension of the pixels in the liquid crystal domain, it is preferable that the wall structure 115b has a certain length. For example, when the wall structure is composed of a plurality of walls, the length of each wall is preferably longer than the length between adjacent walls.

  The pixel electrode 111 illustrated here has two openings 114 and four notches 113 formed at predetermined positions. When a predetermined voltage is applied to the liquid crystal layer, two liquid crystal domains each having an axially symmetric orientation are formed, and the central axis of each of the liquid crystal domains is formed in or near the opening 114. The As will be described later, the opening 114 provided in the pixel electrode 111 acts to fix the position of the central axis of the axially symmetric orientation. The notch 113 is provided in the vicinity of the boundary of the axially symmetric alignment domain, and defines the direction in which the liquid crystal molecules are tilted by the electric field, and acts to form the axially symmetric alignment domain. An oblique electric field is formed around the opening 114 and the notch 113 by a voltage applied between the pixel electrode 111 and the counter electrode 113, and a direction in which liquid crystal molecules are inclined is defined by the oblique electric field. As a result, it operates as described above. Here, the notch 113 is centered on an opening 114 (here, the opening on the right side in FIG. 1) corresponding to the central axis of the liquid crystal domain formed in the pixel (here, the entire transmission region). It includes four notches 113 arranged symmetrically with respect to a point.

  By providing such a notch 113, the direction in which the liquid crystal molecules fall when a voltage is applied is defined, and two liquid crystal domains are formed. In FIG. 1, the reason why the notch is not provided on the left side of the pixel electrode 111 is that the notch provided at the right end of the pixel electrode (not shown) located on the left side of the illustrated pixel electrode 111 has the same effect. Therefore, a notch that reduces the effective aperture ratio of the pixel is omitted at the left end of the pixel electrode 111. Here, since the alignment regulating force by the wall structure 115b described above can also be obtained, a stable liquid crystal domain can be formed as in the case where the notch portion is provided without providing the notch portion on the left end of the pixel electrode 111. In addition, the effect of improving the effective aperture ratio can be obtained.

  Here, four cutout portions 113 are formed, but at least one cutout portion may be provided between adjacent liquid crystal domains. For example, here, a long and thin cutout portion is provided at the center of the pixel. Others may be omitted.

  The shape of the opening 114 provided to fix the central axis of the axially symmetric orientation domain is preferably circular as illustrated, but is not limited thereto. However, in order to exert substantially the same orientation regulating force in all directions, the polygon is preferably a quadrilateral or more, and is preferably a regular polygon. The shape of the notch 113 acting so as to define the direction in which the liquid crystal molecules in the axially symmetric alignment domain are tilted by the electric field is set so as to exert an alignment regulating force substantially equal to the adjacent axially symmetric alignment. A quadrangle is preferred.

  If the support 133 for defining the thickness (also referred to as a cell gap) of the liquid crystal layer 120 is formed in the light shielding region (here, the region defined by the black matrix 132), the display quality is not deteriorated. preferable. The support 133 may be formed on either of the transparent substrates 110a and 110b, and is not limited to being provided on the wall structure 115b provided in the light shielding region as illustrated. When the support 133 is formed on the wall structure 115b, the sum of the height of the wall structure 115b and the height of the support 133 is set to be the thickness of the liquid crystal layer 120. When the support body 133 is provided in a region where the wall structure 115 b is not formed, the height of the support body 133 is set to be the thickness of the liquid crystal layer 120. The support 133 can be formed by a photolithography process using a photosensitive resin, for example.

  In this liquid crystal display device 100, when a predetermined voltage (a voltage equal to or higher than the threshold voltage) is applied to the pixel electrode 111 and the counter electrode 131, the respective central axes are stabilized in or near the two openings 114. Two axially symmetric orientations are formed, and a pair of notches provided at the center in the longitudinal direction of the pixel electrode 11 define the direction in which liquid crystal molecules in two adjacent liquid crystal domains are tilted by an electric field, and the wall structure 115b and The notch 113 provided in the corner portion of the pixel electrode 111 defines the direction in which the liquid crystal molecules near the extension of the pixel in the liquid crystal domain are tilted by the electric field. It is considered that the alignment regulating force by the wall structure 115b, the opening 114, and the notch 113 acts cooperatively to stabilize the alignment of the liquid crystal domain.

  Note that, on the liquid crystal layer 120 side of the transparent substrate 110a, for example, an active element such as a TFT and circuit elements (not shown) such as a gate signal wiring and a source signal wiring connected to the TFT are provided. Further, the transparent substrate 110a, the circuit elements formed on the transparent substrate 110a, and the pixel electrode 111, the wall structure 115b, the support 133, the alignment film, and the like described above may be collectively referred to as an active matrix substrate. On the other hand, the transparent substrate 110b and the color filter layer 130, the black matrix 132, the counter electrode 131, the alignment film, and the like formed on the transparent substrate 110b may be collectively referred to as a counter substrate or a color filter substrate.

  Further, although omitted in the above description, the liquid crystal display device 100 further includes a pair of polarizing plates arranged so as to face each other through the transparent substrates 110a and 110b. The pair of polarizing plates are typically arranged so that the transmission axes are orthogonal to each other. Furthermore, as described later, a biaxial optically anisotropic medium layer and / or a uniaxial optically anisotropic medium layer may be provided.

  Next, an example of the structure of an active matrix substrate that is preferably used in the transmissive liquid crystal display device 100 will be described with reference to FIGS. 2A and 2B. 2A is a partially enlarged view of the active matrix substrate, and FIG. 2B is a cross-sectional view taken along line X-X ′ in FIG. 2A. The active matrix substrate shown in FIGS. 2A and 2B is different from the active matrix substrate shown in FIG. 1 in that the number of notches 113 is small, but other configurations may be the same.

  The active matrix substrate shown in FIGS. 2A and 2B has a transparent substrate 110a made of, for example, a glass substrate, and the gate signal lines 2 and the source signal lines 3 are provided on the transparent substrate 110a so as to be orthogonal to each other. . A TFT 4 is provided in the vicinity of the intersection of these signal wires 2 and 3, and the drain electrode 5 of the TFT 4 is connected to the pixel electrode 111.

  The active matrix substrate has an interlayer insulating film 115a that covers the gate signal line 2, the source signal line 3, and the TFT 4, and the wall structure 115b is formed integrally with the interlayer insulating film 115a. Accordingly, the interlayer insulating film 115a and the wall structure 115b can be formed from a single photosensitive resin film 115, and can be manufactured by a simpler process than the conventional one.

  The pixel electrode 111 is a transparent electrode formed of a transparent conductive layer such as ITO, and is formed on the interlayer insulating film 115a. The drain electrode 5 is connected to a contact portion 111a formed in the contact hole of the interlayer insulating film 115a. In the predetermined region of the pixel electrode 111, as described above, the notch 113 and the opening 114 are provided in order to control the orientation of the axially symmetric orientation domain.

The pixel electrode 111 is superimposed on the gate signal line of the next stage through the gate insulating film 9. The TFT 4 has a structure in which a gate insulating film 9, a semiconductor layer 12, a channel protective layer 13, and an n ⁺ -Si layer 11 (source / drain electrodes) are stacked on the gate electrode 10 branched from the gate signal line 2. doing.

  Note that although a configuration example of a bottom-gate TFT is shown here, the present invention is not limited to this, and a top-gate TFT can also be used. In addition, a switching element (for example, MIM) other than the TFT can be used.

  In the liquid crystal display device 100, the notch 113 and the opening 114 are formed in the pixel electrode 111 provided on the interlayer insulating film 115a formed integrally with the wall structure 115a, and the alignment control structure is formed on the counter substrate 110b side. Is not provided. According to the present embodiment, there is an advantage that a stable axially symmetric alignment domain can be formed with such a simple configuration. However, the present invention is not limited to this. For example, an alignment regulating structure may be provided on the counter substrate 110b side as in the liquid crystal display device 100 'shown in FIG. By adopting such a configuration, the alignment of liquid crystal molecules can be further stabilized.

  The liquid crystal display device 100 ′ has substantially the same configuration as the liquid crystal display device 100 except that the counter electrode 131 has an opening 114 ′. Common reference numerals are used and description thereof is omitted here.

  The opening 114 ′ formed in the counter substrate 131 of the liquid crystal display device 100 ′ is provided at a position substantially overlapping the opening 114 formed in the pixel electrode 111 when viewed from the normal direction of the substrate. The plan view of the display device 100 ′ is substantially the same as FIG. The opening 114 ′ arranged in this way acts to fix and stabilize the central axis of the axially symmetric orientation together with the opening 114 formed in the pixel electrode 111. As a result, the orientation of the axially symmetric orientation domain is further stabilized.

  Note that it is preferable not to provide a structural alignment regulating structure such as a wall structure or a convex portion on the counter substrate 110b side. In order to form a wall structure or the like, unlike an opening or a notch formed in the electrode, the number of manufacturing steps increases, which increases the cost, which is not preferable. Further, unlike the opening having the function of fixing the central axis, the notch 113 is provided so as to define the direction in which the liquid crystal molecules are tilted by the electric field in cooperation with the anchoring action of the side surface of the wall structure 115. It is preferable to provide only on the same substrate 110 a as the wall structure 115.

(Transflective liquid crystal display device)
Next, the configuration of the transflective liquid crystal display device 200 according to the embodiment of the present invention will be described with reference to FIG.

  It is a figure which shows typically the structure of one pixel of the transmissive liquid crystal display device 200 of embodiment by this invention, (a) is a top view, (b) is 2B- in FIG. 4 (a). It is sectional drawing along a 2B 'line.

  The liquid crystal display device 200 includes a transparent substrate (for example, a glass substrate) 210a, a transparent substrate 210b provided to face the transparent substrate 210a, and a vertical alignment type liquid crystal layer provided between the transparent substrates 210a and 210b. 220. A vertical alignment film (not shown) is provided on the surfaces of both the substrates 210a and 210b in contact with the liquid crystal layer 220. When no voltage is applied, the liquid crystal molecules of the liquid crystal layer 220 are in contact with the surface of the vertical alignment film. Oriented substantially vertically. The liquid crystal layer 220 includes a nematic liquid crystal material having a negative dielectric anisotropy, and further includes a chiral agent as necessary.

  The liquid crystal display device 200 includes a pixel electrode 211 formed on the transparent substrate 210a and a counter electrode 231 formed on the transparent substrate 210b, and a liquid crystal provided between the pixel electrode 211 and the counter electrode 231. Layer 220 defines the pixel. Circuit elements such as TFTs are formed on the transparent substrate 210a as will be described later. The transparent substrate 210a and the components formed thereon may be collectively referred to as an active matrix substrate 210a.

  Further, typically, a color filter 230 (corresponding to a plurality of color filters may be collectively referred to as the color filter layer 230) provided corresponding to the pixel on the liquid crystal layer 220 side of the transparent substrate 210b. A black matrix (light shielding layer) 232 provided between adjacent color filters 230 is formed, and a counter electrode 231 is formed thereon, and the color filter layer 230 is formed on the counter electrode 131 (the liquid crystal layer 120 side). Alternatively, a black matrix 232 may be formed. The transparent substrate 210b and the components formed thereon may be collectively referred to as a counter substrate (color filter substrate) substrate 210b.

  The pixel electrode 211 is formed of a transparent electrode 211a formed from a transparent conductive layer (for example, an ITO layer) and a metal layer (for example, an Al layer, an alloy layer including Al, and a laminated film including any of these). A reflective electrode 211b. As a result, the pixel includes a transparent area A defined by the transparent electrode 211a and a reflective area B defined by the reflective electrode 211b. The transparent area A displays in the transmissive mode, and the reflective area B displays in the reflective mode.

  The liquid crystal display device 200 has a light shielding region around each pixel, and has a wall structure 215b on the transparent substrate 210a in the light shielding region. The wall structure 215b is an interlayer insulating film formed so as to cover circuit elements (including not only active elements such as switching elements but also wiring and electrodes: not shown here) formed on the transparent substrate 210a. It is integrally formed with 215a. For example, as will be described later, when an interlayer insulating film is provided in a transmissive liquid crystal display device having a TFT as a circuit element, the pixel electrode can be partially overlapped with the gate signal wiring and / or the source signal wiring. , The aperture ratio can be improved.

  Further, since the light shielding area does not contribute to the display, the wall structure 215b formed in the light shielding area does not adversely affect the display. The wall structure 215b illustrated here is provided as a continuous wall so as to surround the pixel, but is not limited thereto, and may be divided into a plurality of walls. Since the wall structure 215b acts so as to define the boundary formed in the vicinity of the outer extension of the pixels in the liquid crystal domain, it preferably has a certain length. For example, when the wall structure 215b is composed of a plurality of walls, the length of each wall is preferably longer than the length between adjacent walls.

  The pixel electrode 211 exemplified here has three openings 214 and four notches 213 formed at predetermined positions. When a predetermined voltage is applied to the liquid crystal layer, three liquid crystal domains each having an axially symmetric orientation are formed, and the central axis of each of the liquid crystal domains is formed in or near the opening 214. The As will be described later, the opening 214 provided in the pixel electrode 211 acts to fix the position of the central axis of the axially symmetric alignment, and the notch 213 is a direction in which the liquid crystal molecules in the axially symmetric alignment domain are tilted by the electric field. Acts to prescribe. An oblique electric field is formed around the opening 214 and the notch 213 by a voltage applied between the pixel electrode 211 and the counter electrode 213, and a direction in which liquid crystal molecules are inclined is defined by the oblique electric field. As a result, it operates as described above. Further, here, the notch 213 is arranged symmetrically with respect to the opening 214 (here, the opening on the right side in FIG. 1) 214 corresponding to the central axis of the liquid crystal domain formed in the transmission region A of the pixel. 4 cutouts 213 formed therein. By providing such a notch 213, the direction in which the liquid crystal molecules fall when a voltage is applied is defined, and three liquid crystal domains are formed. The arrangement of the openings 214 and the notches 213 and their preferred shapes are the same as those of the transmissive liquid crystal display device 100 described above. Although FIG. 4 shows an example in which two liquid crystal domains are formed in the transmissive region A and one liquid crystal domain is formed in the reflective region B, the present invention is not limited to this. In addition, it is preferable that each liquid crystal domain has a substantially square shape from the viewpoint of viewing angle characteristics and alignment stability.

  If the support 233 for defining the thickness (also referred to as a cell gap) of the liquid crystal layer 220 is formed in the light-shielding region (here, the region defined by the black matrix 232), the display quality is not deteriorated. preferable. The support 233 may be formed on either of the transparent substrates 210a and 210b, and is not limited to the case where the support 233 is provided on the wall structure 215b provided in the light shielding region as illustrated. When the support 233 is formed on the wall structure 215 b, the sum of the height of the wall structure 215 b and the height of the support 233 is set to be the thickness of the liquid crystal layer 220. In the case where the support 233 is provided in the region where the wall structure 215 b is not formed, the height of the support 233 is set to be the thickness of the liquid crystal layer 220.

  In this liquid crystal display device 200, when a predetermined voltage (a voltage equal to or higher than the threshold voltage) is applied to the pixel electrode 211 and the counter electrode 231, the respective central axes are stabilized in or near the three openings 214. Axisymmetric alignment is formed, and the four notches 213 provided in the pixel electrode 211 define the direction in which the liquid crystal molecules in the three adjacent liquid crystal domains are tilted by the electric field, and the wall structure 215b is the liquid crystal domain pixel. Stabilizes the boundary formed near the extension.

  Next, a preferable configuration unique to the transflective liquid crystal display device 200 capable of performing both transmission mode display and reflection mode display will be described.

  In the transmission mode display, the light used for display passes through the liquid crystal layer 220 only once, whereas in the reflection mode display, the light used for display passes through the liquid crystal layer 220 twice. Therefore, as schematically shown in FIG. 4B, it is preferable to set the thickness dt of the liquid crystal layer 220 in the transmissive region A to about twice the thickness dr of the liquid crystal layer 220 in the reflective region B. By setting in this way, the retardation that the liquid crystal layer 220 gives to the light in both display modes can be made substantially equal. Although dt = 0.5dr is most preferable, good display can be realized in both display modes as long as it is within the range of 0.3dt <dr <0.7dt. Of course, dt = dr may be used depending on the application.

  In the liquid crystal display device 200, in order to make the thickness of the liquid crystal layer 220 in the reflective region B smaller than the thickness of the liquid crystal layer in the transmissive region A, the transparent dielectric layer 234 is provided only in the reflective region B of the glass substrate 210b. Yes. By adopting such a configuration, there is no need to provide a step using an insulating film or the like under the reflective electrode 211b, so that there is an advantage that the manufacturing of the active matrix substrate 210a can be simplified. Further, when the reflective electrode 211b is provided over the insulating film for providing a step for adjusting the thickness of the liquid crystal layer 220, light used for transmissive display is blocked by the reflective electrode that covers the inclined surface (tapered portion) of the insulating film. However, since the light reflected by the reflective electrode formed on the slope of the insulating film repeats internal reflection, there is a problem that it is not effectively used for reflective display. Occurrence of problems can be suppressed and light utilization efficiency can be improved.

  Furthermore, if the transparent dielectric layer 234 having a function of scattering light (diffuse reflection function) is used, a good white display close to paper white can be realized without providing the reflection electrode 211b with a diffuse reflection function. it can. Even if the transparent dielectric layer 234 is not provided with a light scattering ability, a white display close to paper white can be realized by providing an uneven shape on the surface of the reflective electrode 211b. The position of the central axis of the symmetric orientation may not be stable. On the other hand, if the transparent dielectric layer 234 having light scattering ability and the reflective electrode 211b having a flat surface are used, the position of the central axis can be more reliably stabilized by the opening 214 formed in the reflective electrode 211b. Benefits are gained. In addition, in order to provide a diffuse reflection function to the reflective electrode 211b, when forming unevenness on the surface, the uneven shape is preferably a continuous wave shape so that no interference color is generated, and the central axis of the axially symmetric orientation is It is preferable to set so that it can be stabilized.

  In the transmissive mode, light used for display passes through the color filter layer 230 only once, whereas in reflective mode display, light used for display passes through the color filter layer 230 twice. Therefore, when a color filter layer having the same optical density is used for the transmission region A and the reflection region B as the color filter layer 230, color purity and / or luminance in the reflection mode may be lowered. In order to suppress the occurrence of this problem, it is preferable to make the optical density of the color filter layer in the reflective region smaller than that in the transmissive region. The optical density here is a characteristic value characterizing the color filter layer, and the optical density can be reduced by reducing the thickness of the color filter layer. Alternatively, the optical density can be reduced by reducing the concentration of the added dye, for example, while maintaining the thickness of the color filter layer.

  Next, an example of the structure of an active matrix substrate that is preferably used in a transflective liquid crystal display device will be described with reference to FIGS. FIG. 5 is a partially enlarged view of the active matrix substrate, and FIG. 6 is a cross-sectional view of the liquid crystal display device, which corresponds to a cross-sectional view along the line X-X ′ in FIG. 5. The active matrix substrate shown in FIGS. 5 and 6 has a configuration in which one liquid crystal domain is formed in the transmissive region A (that is, the number of openings 214 and notches 213 is small). Although different from the active matrix substrate shown in FIG. 4, other configurations may be the same, and common components are denoted by common reference numerals.

  The active matrix substrate shown in FIGS. 5 and 6 includes a transparent substrate 210a made of, for example, a glass substrate, and the gate signal lines 2 and the source signal lines 3 are provided on the transparent substrate 210a so as to be orthogonal to each other. . A TFT 4 is provided in the vicinity of the intersection of these signal lines 2 and 3, and the drain electrode 5 of the TFT 4 is connected to the pixel electrode 211.

  The pixel electrode 211 includes a transparent electrode 211a formed from a transparent conductive layer such as ITO, and a reflective electrode 211b formed from Al or the like. The transparent electrode 211a defines the transmission region A, and the reflective electrode 211b reflects. Region B is defined. Note that a transparent conductive layer may be formed over the reflective electrode 211b as necessary.

  The pixel electrode 211 is formed on the interlayer insulating film 215a, and the pixel electrode 211 (transparent electrode 211a) is connected to the drain electrode 5 at a contact portion 211a formed in the contact hole of the interlayer insulating film 215a. The connection electrode 25 is connected. The reflective electrode 211b is connected to the transparent electrode 211a.

  Further, as shown in FIG. 6, the pixel electrode 211 is preferably extended also on the slope of the wall structure 215b formed integrally with the interlayer insulating film 215a. By extending the pixel electrode 211 up to the slope of the wall structure 215b, an effect of efficiently regulating the direction in which the liquid crystal molecules of the liquid crystal layer tilt when a voltage is applied can be obtained.

  In a predetermined region of the pixel electrode 211, as described above, the notch 213 and the opening 214 are provided in order to control the orientation of the axially symmetric orientation domain. The connection electrode 25 forms an auxiliary capacitance with an auxiliary capacitance wiring (auxiliary capacitance electrode) provided so as to face each other with the gate insulating film 9 interposed therebetween. For example, the auxiliary capacitance line is provided in parallel with the gate signal line 2 below the reflective electrode 211b. For example, the auxiliary capacitor wiring is supplied with the same signal (common signal) as that of the counter electrode provided on the color filter side substrate.

  The reflective electrode 211b of the transflective liquid crystal display device of this embodiment has an uneven surface, and has excellent diffuse reflection characteristics. The uneven shape on the surface of the reflective electrode 211 b reflects the uneven shape formed on the surface of the interlayer insulating film 215.

  The interlayer insulating film 215a is formed integrally with the wall structure 215b, and further, a region having a substantially flat surface (sometimes referred to as a “first region”) and a region having a concavo-convex shape (“ Second region ”). A transparent electrode 211a is formed on the first region having a flat surface, and a reflective electrode 211b is formed on the second region having irregularities. The interlayer insulating film 215a formed integrally with the on-wall structure 215b and including the region 215c having a concavo-convex shape on the surface can be formed from a single photosensitive resin film, as will be described later. It can be manufactured by a simpler process than before.

The pixel electrode 211 is superimposed on the gate signal line 2 in the next stage via the gate insulating film 9. The TFT 4 has a structure in which a gate insulating film 9, a semiconductor layer 12, a channel protective layer 13, and an n ⁺ -Si layer 11 (source / drain electrodes) are stacked on the gate electrode 10 branched from the gate signal line 2. doing.

  Note that although a configuration example of a bottom-gate TFT is shown here, the present invention is not limited to this, and a top-gate TFT can also be used. In addition, a switching element (for example, MIM) other than the TFT can be used.

  As described above, the liquid crystal display device 200 having the configuration shown in FIG. 4 is similar to the liquid crystal display device 100 in that the alignment regulating structure (the opening formed in the pixel electrode 211) has an axially symmetric orientation only on one substrate. 213, the notch 214 and the wall structure 215b) are provided with a comparatively simple structure, which has an effect that the alignment of the liquid crystal can be sufficiently stabilized. Note that, in the transflective liquid crystal display device 200 as in the transmissive liquid crystal display device 100 ′ illustrated in FIG. 3, the alignment can be further stabilized by providing the alignment regulating structure on the counter substrate side. However, for the reasons described above, it is preferable that the orientation regulating structure provided on the counter substrate is only an opening for fixing the central axis of the axially symmetric orientation.

  Furthermore, the liquid crystal display device 200 can improve display brightness and color purity in the transmissive mode and the reflective mode by configuring the transparent attractant layer 234 and / or the color filter layer 230 as described above.

  Next, a method for forming the interlayer insulating layer 215a and the wall structure 215b will be described in detail with reference to FIG. In FIG. 6, the transparent substrate 210a and circuit elements such as TFTs and signal wirings formed thereon are collectively referred to as “circuit board 210A”.

  First, as shown in FIG. 6A, a circuit board 210A on which predetermined circuit elements such as TFTs are formed is prepared, and a positive photosensitive resin film (for example, Tokyo Ohka Co., Ltd.) is provided so as to cover the circuit elements. Manufactured, OFPR-800). The thickness of the photosensitive resin film is, for example, 4.5 μm.

  Next, as shown in FIG. 6B, the photosensitive resin film is exposed. At this time, predetermined regions having different exposure amounts are formed. That is, exposure is performed for each region to be a wall structure 215b (a region shielded from light by a source signal wiring or a gate signal wiring), a region in which unevenness is formed on a surface (a region in which a reflective electrode is formed), and a region in which a contact hole is formed. Change the amount.

Specifically, a light shielding part 52a is provided at a position corresponding to the convex part (the convex part of the concave / convex surface) formed in the reflective region and the wall structure, and the other is provided through a photomask 52 which is a light transmitting part 52b. Then, the photosensitive resin film 215 is exposed. The shape of the light-shielding part 52a corresponding to the convex part formed in the reflection region is, for example, a circular shape or a polygonal shape, and is randomly arranged with a predetermined center interval (5 to 30 μm) and a predetermined density. As the light source, for example, an ultrahigh pressure mercury lamp (for example, illuminance of i-line: 20 to 50 mW) is used, and exposure is performed uniformly (irradiation time: 1 to 4 seconds). For example, the exposure amount is preferably about ²⁰ to 100 mJ / cm ² .

Next, as shown in FIG. 6C, exposure is performed uniformly using a photomask 62 having a light transmitting portion 62b corresponding to the contact hole portion and the other being a light shielding portion 62a (irradiation time: 10 to 10). 15 seconds). The amount of exposure is preferably about 200 to 500 mJ / cm ² , for example.

  Next, as shown in FIG. 6D, development processing is performed under predetermined conditions using, for example, a TMAH (tetramethylammonium hydroxide) developer. For example, the resin film in the high exposure area is completely removed (contact holes are formed), and about 90% of the resin film in the unexposed area remains (wall structures and protrusions are formed), resulting in low exposure. About 40% of the resin film in the region remains (recesses are formed).

  Further, as shown in FIG. 6 (e), drying and baking are performed as necessary. Firing is performed at 200 ° C., for example. By performing the baking, a smooth uneven shape 215c is obtained due to a thermal sag phenomenon or the like of the resin in the reflective region 215c 'formed with a plurality of fine protrusions. By making the surface of the reflective electrode 211b smooth and uneven, it is possible to obtain good diffuse reflection characteristics in which the generation of interference colors is suppressed.

  In this way, a continuous batch exposure process is performed on the photosensitive resin film 215, and a subsequent development process is performed, so that the region 215c and the contact hole which are formed integrally with the wall structure 215b and have a fine uneven shape are formed. Thus, an interlayer insulating film 215a having the following can be obtained.

  In the above exposure process, the method of forming regions with different exposure amounts by adjusting the irradiation time for each region using a photomask having a light transmitting portion and a light shielding portion has been described. An interlayer insulating film having a surface whose shape continuously changes can also be formed by performing exposure using a grayscale mask having a changing shading pattern.

  Further, in the exposure process, a third photomask having only a region where the wall structure is formed is used as a light shielding portion, and the exposure for forming the wall structure is continuously performed before the exposure process for forming the contact hole. It is also possible to do this.

  Next, as shown in FIG. 6F, the pixel electrode 211 is formed on the interlayer insulating film 215a and the wall structure 215b obtained through the above-described steps. For example, the transparent electrode 211a is obtained by depositing and patterning a transparent conductive film (for example, an ITO film) to a predetermined film thickness (for example, 100 nm) by a sputtering method. The reflective electrode 211b is formed by depositing a reflective electrode film (for example, an Al thin film) to a predetermined film thickness (for example, 180 nm) by sputtering and patterning. When forming each electrode 211a and 211b, an opening part and / or a notch part are formed.

  According to the present embodiment, the wall structure 215b and the fine uneven shape of the reflective electrode portion are formed in the same layer as the interlayer insulating film layer 215a, and the pixel electrode is formed in the upper layer, so that the wall structure In particular, it is possible to dispose the pixel electrode on the inclined side surface on the pixel side. By extending the pixel electrode 211 on the inclined side surface of the wall structure, the electric field (electric field lines) around the side surface of the wall structure 215b is distorted, so that it is combined with the structural orientation regulating force by the wall structure 215b. As a result, the effect of efficiently regulating the tilt direction of the liquid crystal molecules is brought about.

  In addition, you may form a transparent electrode film on the reflective electrode 211b as needed. By forming a transparent conductive film over the reflective electrode 211b, it is possible to reduce a difference in potential difference (electrode potential difference) between the reflective region and the transmissive region. The material of the transparent electrode film formed on the reflective electrode 211b is preferably the same material as the transparent electrode 211a.

  As described above, according to the manufacturing method of the present embodiment, the concavo-convex structure for expressing the diffuse reflection characteristics and the wall structure as the orientation control structure can be obtained simply by performing the photolithography process on the single photosensitive resin film. A body can be formed, and cost reduction can be effectively performed.

  Hereinafter, after forming a vertical alignment film on a counter substrate (CF substrate) facing the active matrix substrate obtained as described above under a predetermined condition, these are bonded to each other through a seal resin, and the gap is formed in the gap. By enclosing a liquid crystal material having a negative dielectric anisotropy, the liquid crystal display device of this embodiment can be obtained. Since these steps are performed by a known method, description thereof is omitted.

  Although an example of a method for manufacturing a transflective liquid crystal display device has been described here, a wall structure, a contact hole, and the like, which are one of the alignment regulation structures of the liquid crystal domain, are collectively used when forming an interlayer insulating film layer. The technology that is manufactured in a continuous process can also be applied to transmissive liquid crystal display devices and reflective liquid crystal display devices. Of course, this is a simpler process than conventional methods, and has the effect of reducing costs and shortening the tact time during production. Play.

  Next, preferred shapes of the wall structure 215b and the interlayer insulating film 215a will be described in more detail with reference to FIGS. 8 (a) and 8 (b). 8A and 8B are cross-sectional views taken along the line 8A-8A 'in FIG. 4, and FIG. 8B is an enlarged view of a portion surrounded by a broken line in FIG. 8A. .

  According to the embodiment of the present invention, as described above, the interlayer insulating film 215a and the wall structure 215b, which are upper layers of the switching elements, are integrally formed through a batch exposure process. Therefore, as schematically shown in FIGS. 8A and 8B, the cross-sectional shape of the wall structure 215b and the interlayer insulating film 215a in the plane perpendicular to the first substrate 210a is the center of the axially symmetric alignment of the liquid crystal domain. The region where the shaft is formed can be a continuous shape with the bottom 215B. Here, since the pixel electrode 211a has the opening 214 for fixing and stabilizing the position of the central axis of the axially symmetric alignment domain, the bottom 215B of the cross-sectional shape of the interlayer insulating film 215a corresponds to the opening 214. Formed in position.

  As described above, when the inclined side surface 215S of the wall structure 215b and the upper surface of the interlayer insulating film 215a have a continuous mortar shape, the pixel electrode 211 and the vertical alignment film formed on the mortar-shaped surface allow the axially symmetric alignment. The domain orientation can be further stabilized. As a result, it is possible to obtain the effect of improving the response characteristics in the halftone, the effect of reducing the rough feeling of the display in the halftone, and the effect of recovering in a short time even if the alignment disorder occurs when the liquid crystal panel is pressed. it can. Note that the effect of stabilizing the alignment by forming a mortar shape is obtained because the surfaces of the pixel electrode and the vertical alignment film are formed in a mortar shape. That is, the pixel electrode having a mortar-shaped surface generates an electric field inclined about the bottom of the mortar with respect to the liquid crystal layer, and the vertical alignment film having the mortar-shaped surface allows liquid crystal molecules to center on the bottom of the mortar. Demonstrate the ability to regulate orientation so that it tilts. As described above, since the alignment regulating force due to the mortar-like shape is additionally obtained, the axially symmetric alignment domain is further stabilized.

  8A and 8B, the mortar shape is exaggerated, but the cross-sectional shape including the surface perpendicular to the substrate 210a has a gentle slope near the side surface of the wall structure. In addition, it is preferable that the central portion of the pixel region has a substantially flat structure or a structure that continuously inclines from the side surface of the wall structure toward the central portion. If it has such a cross-sectional shape, the effect of stabilizing the axially symmetric alignment domain can be obtained. The mortar shape can be controlled by, for example, patterning the photosensitive resin film constituting the interlayer insulating film 215a and the wall structure 215b, and then adjusting the temperature and time of the heat treatment step.

  As schematically shown in FIG. 8B, the inclination angle α of the side surface 215S of the wall structure 215b with respect to the surface of the substrate 210a is preferably 45 ° or less, and preferably 25 ° or less. .

  The vertical alignment film (not shown) formed on the side surface 215S of the wall structure 215b has a regulating force so that the liquid crystal molecules are aligned perpendicular to the surface thereof, so that the liquid crystal molecules on the side surface 215 are the substrate 210a. Oriented in a direction inclined with respect to the surface. The degree of inclination of the liquid crystal molecules increases as the inclination angle α of the side surface 215S increases. Since the alignment regulating force by the vertical alignment film acts regardless of the presence or absence of voltage, light leakage due to tilted liquid crystal molecules in the vicinity of the side surface 215S occurs in the black display state. Therefore, when the inclination angle α of the side surface 215S of the wall structure 215b is too large, the contrast ratio is lowered. In order to suppress the decrease in the contrast ratio, the inclination angle α is preferably 45 ° or less, and more preferably 25 ° or less. When the inclination angle α exceeds 45 °, the orientation may become unstable. When no voltage is applied, the liquid crystal molecules that are tilted with respect to the horizontal plane at the wall side face will move so that the liquid crystal molecules are aligned perpendicular to the distorted electric field when the voltage is applied. This is thought to be because the horizontal direction that should naturally fall over and the opposite direction. In order to obtain the effect of stabilizing the orientation, the inclination angle α is preferably 3 ° or more, and more preferably 5 ° or more.

  Next, a preferred arrangement of the support that defines the thickness of the liquid crystal layer will be described with reference to FIG. FIG. 9 is a plan view schematically showing the structure of a transflective liquid crystal display device 300 according to another embodiment of the present invention.

  Since the liquid crystal display device 300 has a structure similar to that of the liquid crystal display device 200 described above, differences from the liquid crystal display device 200 will be mainly described below.

  The liquid crystal display device 300 has pixels arranged in a delta arrangement. The pixel electrode 311 that defines a pixel includes a transparent electrode 311a and a reflective electrode 311b. The pixel electrode 311 has three openings 314 and four notches 313 formed at predetermined positions. Like the liquid crystal display device 200, when a predetermined voltage is applied to the liquid crystal layer, Three liquid crystal domains having an axially symmetric orientation are formed, and the central axis of each of the liquid crystal domains is formed in or near the opening 314.

  The liquid crystal display device 300 has a light shielding region around the pixel, and has a wall structure 315b on a transparent substrate in the light shielding region. Similarly to the liquid crystal display device 200, the wall structure 315b is formed integrally with an interlayer insulating film (not shown) formed so as to cover circuit elements formed on the transparent substrate. In the liquid crystal display device 200, the wall structure 215b is provided as a continuous wall so as to surround the pixels. However, in the liquid crystal display device 300, the wall structure 215b is composed of walls (wall portions) separated by a wall gap 315S. Yes. In addition, a support (spacer) 333 for defining the thickness (cell thickness) of the liquid crystal layer is provided in the wall gap 315 </ b> S that separates the wall structure 315.

  Thus, by separating the wall structure 315 by the wall gap 315S and arranging the support body 333 in the wall gap 315S, the following effects can be obtained.

  As described above, there are variations in the finished shape and height of the wall structure 315 due to the effect of the process margin and the case where the interlayer insulating film and the wall structure are formed through a batch of photolithography processes. Sometimes. Therefore, if the support is provided on the wall structure, even if the variation in the height of the support is suppressed, the thickness of the liquid crystal layer varies due to the influence of the variation in the height and shape of the wall structure. become. Therefore, in order to suppress variation in the thickness of the liquid crystal layer, it is preferable to provide a wall gap 315S that separates the wall structure 315 and dispose the support 333 there like the liquid crystal display device 300. Note that the support 333 may be formed on the active matrix substrate side or may be formed on the counter substrate side. In addition, by providing the wall gap 315, an effect of shortening the injection time of the liquid crystal material can be obtained. Since the support 333 is provided in the light shielding region, the display quality is not deteriorated, and the thickness of the liquid crystal layer can be made uniform over the entire panel by arranging the support 333 at an appropriate density. The impact resistance of the panel can be improved.

  However, when the width of the wall gap 315S becomes too large, the orientation control effect by the wall structure 315 is reduced. As a result of various investigations, the length of the wall gap existing around one pixel (the total length of the plurality of wall gaps when a plurality of wall gaps are provided around the pixel) is the length of the circumference of the pixel. Is preferably 40% or less. In other words, in order to sufficiently exert the alignment regulating force of the wall structure 333, the length of the wall structure 315 is preferably 60% or more with respect to the peripheral length of the pixel. Here, as shown in FIG. 9, the peripheral length of a pixel is given by 2 × (PL + PS) where PS is the pitch in the row direction of the pixel and PL is the pitch in the column direction. Further, the length of the wall structure 315 indicates the length of a line passing through the central portion of the wall structure 315 in the width direction.

In addition, as a result of various investigations, the arrangement density of the support 333 disposed in the liquid crystal cell is determined by determining the diameter of the support 333 as WL (μm) and the regular unit of the support 333 (0.12 mm ² , here, vertical: horizontal = In correspondence with the aspect ratio of the display panel of 3: 4, the arrangement number in the region of 0.3 mm length × 0.4 mm width) is N (pieces) and the long side pitch of the pixels is PL (μm). When the density D is expressed by WL × N / PL, the arrangement density D preferably satisfies the relationship of 0.01 ≦ D ≦ 0.3, and satisfies the relationship of 0.05 ≦ D ≦ 0.2. Further preferred.

Thus, the preferable arrangement density D of the supports is related to the pixel long side pitch PL, the support diameter WL, and the number N of supports per regular unit (here, 0.12 mm ² ). If the pitch is large, the arrangement density D tends to decrease, and if the pixel pitch is reduced by increasing the definition, the arrangement density tends to increase. In particular, in order to make the cell thickness in the panel uniform and improve the impact resistance, it is important to optimize the arrangement density D of the support. In addition, when the arrangement density D of the support is smaller than the lower limit allowable value, the uniformity of the cell thickness is lowered, the impact resistance is lowered, and the alignment disorder at the time of pressing becomes a problem. Furthermore, when the arrangement density D of the support is larger than the upper limit allowable value, the orientation of the liquid crystal molecules is disturbed near the support, and the contrast ratio may be lowered due to light leakage.

  FIG. 9 is not limited to the liquid crystal display device having the pixels in the delta arrangement, and can be applied to a liquid crystal display device having pixels in the stripe arrangement and other arrangements. Needless to say, the present invention is not limited to the illustrated transmissive / reflective liquid crystal display device, and can be applied to a transmissive display device and a reflective display device.

〔Operating principle〕
The reason why the liquid crystal display device of the embodiment of the present invention having the vertical alignment type liquid crystal layer has excellent wide viewing angle characteristics will be described with reference to FIG.

  10A and 10B are diagrams for explaining the action of the alignment regulating force by the opening 15 provided in the pixel electrode 6, where FIG. 10A is a state when no voltage is applied, and FIG. 10B is an alignment state of liquid crystal molecules when a voltage is applied. Is schematically shown. The state shown in FIG. 10B is a state where a halftone is displayed.

  The liquid crystal display device shown in FIG. 10 has an insulating film layer 16, a pixel electrode 6 having an opening 15, and an alignment film 22 in this order on a transparent substrate 1. On the other transparent substrate 17, the color filter layer 18, the counter electrode 19, and the alignment film 32 are formed in this order. The liquid crystal layer 20 provided between the two substrates includes liquid crystal molecules 21 having negative dielectric anisotropy.

  As shown in FIG. 10A, when no voltage is applied, the liquid crystal molecules 21 are aligned substantially perpendicular to the substrate surface by the alignment regulating force of the vertical alignment films 22 and 32.

  On the other hand, when a voltage is applied, as shown in FIG. 10B, the liquid crystal molecules 21 having negative dielectric anisotropy tend to have the molecular long axis perpendicular to the lines of electric force. The direction in which the liquid crystal molecules 21 are tilted is defined by the formed oblique electric field. Therefore, for example, it is oriented in an axially symmetrical manner with the opening 15 as the center. In this axially symmetric alignment domain, the liquid crystal directors are aligned in all directions (directions in the substrate plane), so that viewing angle characteristics are excellent.

  Here, the action of the oblique electric field formed around the opening 15 has been described, but an oblique electric field is similarly formed in the vicinity of the notch formed at the edge of the pixel electrode 6, and the liquid crystal molecules 21. The direction in which is tilted by the electric field is defined. Further, the wall structure defines the direction in which the liquid crystal molecules 21 are tilted by the alignment regulating force of the side surface (wall surface). Typically, since the vertical alignment film is formed so as to cover the wall structure, the liquid crystal molecules are subjected to a regulating force so as to be aligned perpendicular to the wall surface.

  Next, a more specific configuration example of the liquid crystal display device according to the embodiment of the present invention will be described with reference to FIG.

  The liquid crystal display device shown in FIG. 11 includes a backlight, a transflective liquid crystal panel 50, a pair of polarizing plates 40 and 43 provided so as to face each other through the transflective liquid crystal panel 50, and the polarizing plate 40. Quarter wave plates 41 and 44 provided between the liquid crystal panel 50 and the liquid crystal panel 50, and the optical anisotropy provided between the quarter wave plates 41 and 44 and the liquid crystal panel 50 is negative. The phase difference plates 42 and 45 are included. The liquid crystal panel 50 includes a vertical alignment type liquid crystal layer 20 between a transparent substrate (active matrix substrate) 1 and a transparent substrate (counter substrate) 17. Here, a liquid crystal panel 50 having the same configuration as that of the liquid crystal display device 200 shown in FIG. 4 is used.

  The display operation of the liquid crystal display device shown in FIG. 11 will be briefly described below.

  For the reflection mode display, incident light from above passes through the polarizing plate 43 and becomes linearly polarized light. This linearly polarized light becomes circularly polarized light when it enters the quarter wavelength plate 44 so that the transmission axis of the polarizing plate 43 and the slow axis of the quarter wavelength plate 44 are 45 °, and is formed on the substrate 17. It passes through a color filter layer (not shown). Here, a phase difference plate 45 that does not give a phase difference to light incident from the normal direction is used.

  When no voltage is applied, since the liquid crystal molecules in the liquid crystal layer 20 are aligned substantially perpendicular to the substrate surface, the incident light is transmitted with a phase difference of approximately 0 and is reflected by the reflective electrode formed on the lower substrate 1. The The reflected circularly polarized light passes through the liquid crystal layer 20 again, passes through the color filter layer, passes again through the retardation plate 45 having negative optical anisotropy as circularly polarized light, passes through the quarter-wave plate 44, and then first. The light is converted into linearly polarized light having a polarization direction orthogonal to the polarization direction when passing through the polarizing plate 43 and reaches the polarizing plate 43, so that light cannot pass through the polarizing plate 43 and is displayed in black.

  On the other hand, when a voltage is applied, the liquid crystal molecules in the liquid crystal layer 20 are inclined in the horizontal direction from the direction perpendicular to the substrate surface, so that the incident circularly polarized light becomes elliptically polarized light due to the birefringence of the liquid crystal layer 20 and is formed on the lower substrate 1. Reflected by the reflected electrode. The reflected light is further broken in the polarization state by the liquid crystal layer 20, passes through the liquid crystal layer 20 again, passes through the color filter layer, passes through the retardation plate 45 having negative optical anisotropy again, and becomes 1/4. Since the light is incident on the wave plate 44 as elliptically polarized light, all the light does not become linearly polarized light orthogonal to the polarization direction at the time of incidence when reaching the polarizing plate 43, and part of the light is transmitted through the polarizing plate 43. In particular, by adjusting the applied voltage, the direction in which the liquid crystal molecules are tilted can be controlled, and the amount of light that can be reflected by the polarizing plate 43 is modulated, thereby enabling gradation display.

  Regarding the display of the transmission mode, the two upper and lower polarizing plates 43 and 40 are arranged so that their transmission axes are orthogonal to each other, and the light emitted from the light source becomes linearly polarized light by the polarizing plate 40, This linearly polarized light becomes circularly polarized light and has a negative optical anisotropy when incident on the ¼ wavelength plate 41 so that the slow axis between the transmission axis of the polarizing plate 40 and the ¼ wavelength plate 41 is 45 °. The light enters the transmission region A of the lower substrate 1 through the phase difference plate 42. Here, a phase difference plate 42 that does not give a phase difference to light incident from the normal direction is used.

  When no voltage is applied, the liquid crystal molecules in the liquid crystal layer 20 are aligned substantially perpendicular to the substrate surface, so that incident light is transmitted with a phase difference of approximately 0 and is incident on the lower substrate 1 in a circularly polarized state. In the state of circular polarization, the light passes through the liquid crystal layer 20 and the upper substrate 17 and passes through the retardation plate 45 having the negative optical anisotropy to reach the quarter-wave plate 44. Here, the slow axis of the lower ¼ wavelength plate 41 and the upper ¼ wavelength plate 44 intersect each other by 90 °, so that the upper ¼ wavelength plate 44 is separated by the polarizing plate 40. The linearly polarized light is orthogonal to the linearly polarized light, and is absorbed by the polarizing plate 43 to display black.

  On the other hand, when a voltage is applied, since the liquid crystal molecules 21 in the liquid crystal layer 20 are inclined in the horizontal direction from the direction perpendicular to the substrate surface, the circularly polarized light incident on the liquid crystal display device becomes elliptically polarized light due to the birefringence of the liquid crystal layer 20, and the upper side. Since the CF substrate 16 and the retardation plate 45 and the quarter wavelength plate 44 having negative optical anisotropy on the upper side reach the polarizing plate 43 as elliptically polarized light, the linearly polarized light orthogonal to the polarization component at the time of incidence is not obtained. Instead, light passes through the polarizing plate 43. In particular, by adjusting the applied voltage, the direction in which the liquid crystal molecules are tilted can be controlled, and the amount of light that can be reflected by the polarizing plate 43 is modulated, thereby enabling gradation display.

  A retardation plate having a negative optical anisotropy minimizes the amount of change in retardation when the viewing angle is changed in a vertically aligned state of liquid crystal molecules, and suppresses black floating on the wide viewing angle side. Further, a biaxial retardation plate in which a retardation plate having negative optical anisotropy and a quarter wavelength plate are integrated may be used.

  When a normally black mode in which black display is performed when no voltage is applied and white display is performed when a voltage is applied as in the present invention is performed in an axially symmetric alignment domain, a pair of quarter wavelengths are formed above and below the liquid crystal display device (panel). By providing the plate, it is possible to improve the brightness by eliminating the extinction pattern caused by the polarizing plate. In addition, when the normally black mode is performed in the axially symmetric alignment domain by arranging the transmission axes of the upper and lower polarizing plates orthogonally to each other, in principle, the same degree as that of a pair of polarizing plates arranged in crossed Nicols. Since a black display can be realized, an extremely high contrast ratio can be realized, and a wide viewing angle characteristic led to an omnidirectional orientation can be achieved.

  Below, the specific example regarding this invention is described and demonstrated.

(Example 1)
A liquid crystal display device was configured by arranging an active matrix substrate having the configuration shown in FIG. 6 and a color filter substrate in which a color filter layer, a transparent dielectric layer 234 layer, and a counter electrode were laminated on the opposite side.

  In the active matrix substrate of this example, the interlayer insulating film and the wall structure were formed by the above-described process under the following exposure conditions.

The first exposure step for forming the concavo-convex shape and the wall structure on the positive photosensitive resin film is performed using the first photomask 52 under a low exposure amount condition (60 mJ / cm ² ), and contact The second exposure step for forming holes and the like was performed using the second photomask 62 under a high exposure amount condition (300 mJ / cm ² ). Then, the active matrix substrate of the present example was obtained by executing the series of steps described above. The baking step after development was performed at 200 ° C. for 1 hour. As a result, a wall structure having a height of about 1.2 μm, a width of about 13 μm, and a side surface inclination angle α of about 10 ° was obtained, and a mortar-like cross-sectional shape was obtained.

  On the other hand, in the color filter substrate, a step of the transparent dielectric layer is arranged in the reflection region, and a support (dielectric) provided to define the liquid crystal layer thickness in the light shielding layer portion outside the display pixel is formed.

  After forming a vertical alignment film on the active matrix substrate and the color filter substrate under a predetermined condition (no rubbing treatment), the substrates are bonded together with a seal resin, and a liquid crystal material having a negative dielectric anisotropy ( Refractive index anisotropy Δn; 0.1 and dielectric anisotropy Δε; −4.5) were injected and sealed to prepare a liquid crystal display panel. In this example, the liquid crystal layer thickness dt in the transmissive region was 4 μm, and the liquid crystal layer thickness dr in the reflective region was 2.1 μm.

  Subsequently, an optical film was disposed on both sides of the liquid crystal display panel for the following, to obtain a liquid crystal display device.

  The configuration of the liquid crystal display device of the present embodiment includes a polarizing plate (observation side), a quarter-wave plate (retardation plate 1), and a retardation plate with negative optical anisotropy (retardation plate 2) in this order from the viewer side. (NR plate)), liquid crystal layer (upper side: color filter substrate, lower side: active matrix substrate), retardation plate with negative optical anisotropy (retardation plate 3 (NR plate)), quarter wavelength plate ( The phase difference plate 4) and the polarizing plate (backlight side) were laminated. In addition, in the upper and lower quarter-wave plates (the phase difference plate 1 and the phase difference plate 4) of the liquid crystal layer, their slow axes were orthogonal to each other, and each phase difference was set to 140 nm. Retardation plates having negative optical anisotropy (retardation plate 2 and retardation plate 3) each have a retardation of 135 nm. The two polarizing plates (observation side and backlight side) were arranged with their absorption axes orthogonal to each other.

  A drive signal was applied to the obtained liquid crystal display device (4 V was applied to the liquid crystal layer) to evaluate display characteristics.

  FIG. 12 shows the results of viewing angle-contrast characteristics in transmissive display. The viewing angle characteristics in the transmissive display are almost omnidirectional and symmetric, the CR> 10 region is as good as ± 80 °, and the transmissive contrast is as high as 300: 1 or more in the front.

  On the other hand, the characteristics of the reflective display are evaluated by a spectrocolorimeter (CM 2002 manufactured by Minolta Co., Ltd.), about 8.6% (converted value of aperture ratio 100%) based on the standard diffusion plate, and the contrast value of the reflective display is 21. Therefore, the contrast was high as compared with the conventional liquid crystal display device.

  In addition, it was confirmed that the rough feeling in the halftone (gradation level 2 at the time of eight gradation division) was also improved. Furthermore, the halftone response time (time required for the change from gradation level 3 to gradation level 5 when divided into eight gradations; m seconds) is 38 msec, and the wall structure is integrated with the interlayer insulating film in a continuous process. In contrast, the liquid crystal display device has a characteristic equal to or higher than that of a liquid crystal display device having a structure in which a wall structure is formed in a later process.

  In addition, the alignment disturbance generated when the display panel was pressed with the fingertip when the voltage of 4 V was applied (white display) was recovered immediately after the pressing was stopped. Thus, the on-wall structure formed so as to substantially surround the pixel, and a mortar shape that continuously changes from the side surface of the on-wall structure provided around the pixel toward the center of the pixel. The alignment stability of the axially symmetric alignment domain was improved by the pixel electrode and the vertical alignment film formed on the surface of the substrate.

  In addition, when the cross-sectional shape is not a mortar shape, when the inclination angle of the side surface of the wall-shaped structure exceeds 45 °, the contrast ratio does not reach 300: 1, or the alignment disorder due to pressing occurs. Something was seen.

(Example 2)
A semi-transmission type liquid crystal display device having the structure shown in FIG. 9 was manufactured in the same process as in Example 1 (Prototype Examples 1 to 6). In each prototype, the diameter WL (μm) of the support, the number N of the support per regular unit (here 0.12 mm ² ), the long side pitch PL (μm) of the pixel, and the regular unit Table 1 shows the arrangement density D. For each liquid crystal panel, the results of evaluating the front contrast ratio and impact resistance when a voltage of 4 V was applied are also shown. For the front contrast ratio, the design value was 300, and the lower limit allowable value was 270. In the impact resistance evaluation, the time until the orientation was restored (returned to the original orientation state) after pressing the panel with a pressure of 1 kgf / cm ² was evaluated. The case where the orientation was restored from the defective orientation to the normal orientation within 1 minute was marked as ◯, the case where the orientation was restored from the defective orientation within 5 minutes over 1 minute, and the case where the alignment disorder remained after 10 minutes.

  As can be seen from the results in Table 1, when the relationship of the arrangement density D0.01 ≦ D ≦ 0.3 in the regular unit of the support is satisfied, even if orientation failure occurs due to pressing, it is restored within 5 minutes. . Furthermore, when the arrangement density D is in the range of 0.05 ≦ D ≦ 0.2, it is possible to recover from the orientation failure within 1 minute. Further, all of these prototype examples excellent in impact resistance have a front contrast ratio of 270 or more, and have a good display quality.

  Further, in all of the prototypes shown in Table 1, the length of the wall gap existing around one pixel (when a plurality of wall gaps are provided around the pixel, the total length of the plurality of wall gaps) Is 40% or less with respect to the peripheral length of the pixel, and has a good response characteristic (for example, halftone; about 50 ms at room temperature by changing from gradation level 3 to gradation level 5 in 8 gradation divisions) Below). On the other hand, when the length of the wall gap exceeds 60%, a sufficient axisymmetric orientation cannot be formed, or the response time becomes long because the orientation in the halftone is not sufficiently stabilized (for example, halftone; In some cases, the change from the gradation level 3 to the gradation level 5 in the eight gradation division causes a problem such as about 150 ms or more at room temperature.

(Comparative example)
An ECB mode homogeneous alignment liquid crystal display panel was manufactured using a liquid crystal panel having the same configuration as the liquid crystal panel of the example. The liquid crystal panel of the comparative example is not formed with a wall structure or an opening or notch of the pixel electrode. In addition, the liquid crystal panel of the comparative example uses a horizontal alignment film instead of the vertical alignment film of the liquid crystal panel of the embodiment, and the liquid crystal layer has a liquid crystal material (Δn; 0.07, Δε having positive dielectric anisotropy). 8.5) was injected to form a homogeneously oriented liquid crystal layer. The liquid crystal layer thickness dt in the transmissive region was 4.3 μm, and the liquid crystal layer thickness dr in the reflective region was 2.3 μm.

  A liquid crystal display device of a comparative example was obtained by arranging optical films formed of a plurality of optical layers including retardation plates such as polarizing plates and quarter-wave plates on both surfaces of the liquid crystal display panel.

  A drive signal was applied to the liquid crystal display device of this comparative example (4 V was applied to the liquid crystal layer), and display characteristics were evaluated according to the same evaluation method as in the example.

  The viewing angle characteristics in transmissive display were ± 30 ° in the region of CR> 10, and the gradation inversion was significant. The transmission contrast was 140: 1. On the other hand, the characteristics of the reflective display are about 9.3% (value converted to 100% aperture ratio) with respect to the standard diffusion plate, the contrast value of the reflective display is 8, and the display image is compared with the embodiment in the vertical mode. White contrast was low and blurred.

  As described above, the liquid crystal display device according to the embodiment of the present invention has a transmissive and reflective display by applying the vertical alignment mode to the transmissive display and the reflective display as compared with the conventional homogeneous liquid crystal display device and the conventionally known technology. A good contrast ratio can be obtained in both reflection displays.

  Furthermore, in the embodiment of the present invention, the regulation structure (wall structure and opening or notch) of the liquid crystal domain alignment is disposed only on one side substrate (illustratively, active matrix substrate), and the wall structure is disposed between the layers. The manufacturing process can be simplified because it can be integrated with the insulating film layer and can be continuously formed in a batch with the formation of the fine irregularities of the reflecting portion and the contact hole forming step. In addition, it is possible to regulate the direction in which the liquid crystal molecules fall when a voltage is applied in the rubbing-less process by the alignment regulating force of the wall structure, the opening, or the notch. In addition, as exemplified in the embodiment of the present invention, by providing a liquid crystal domain alignment regulating structure, a plurality of liquid crystal domains that exhibit axial symmetry when a voltage is applied are formed for each pixel. Angular characteristics can be realized.

  As described above, the liquid crystal display device according to the present invention can realize a liquid crystal display device with excellent display quality with a relatively simple configuration. The present invention is suitably applied to a transmissive liquid crystal display device and a transflective (transmission / reflection) liquid crystal display device. In particular, the transflective liquid crystal display device is suitably used as a display device for mobile devices such as mobile phones.

It is a figure which shows typically the structure of one pixel of the transmissive liquid crystal display device 100 of embodiment by this invention, (a) is a top view, (b) is 1B- in FIG. 1 (a). It is sectional drawing along a 1B 'line. It is a top view which shows typically the structure of the active matrix substrate of the other transmissive liquid crystal display device of embodiment by this invention. It is sectional drawing which shows typically the structure of the active matrix substrate shown to FIG. 2A. It is sectional drawing which shows typically the structure of the other transmissive liquid crystal display device 100 'of embodiment by this invention. It is a figure which shows typically the structure of one pixel of the transflective liquid crystal display device 200 of embodiment by this invention, (a) is a top view, (b) is 4B in Fig.4 (a). It is sectional drawing along the -4B 'line. It is a top view which shows typically the structure of the active matrix substrate of the transflective liquid crystal display device of embodiment by this invention. It is sectional drawing which shows typically the structure of a liquid crystal display device provided with the active matrix substrate shown in FIG. FIGS. 5 and 6 are schematic views for explaining a method of manufacturing an active matrix substrate. (A) And (b) is sectional drawing along the 8A-8A 'line of FIG. 4, (b) is an enlarged view of the part enclosed with the broken line of (a). It is a top view which shows typically the structure of the transflective liquid crystal display device 300 of other embodiment by this invention. It is the schematic explaining the operation | movement principle of the liquid crystal display device of embodiment by this invention, (a) shows the time at the time of no voltage application, and (b) at the time of voltage application, respectively. It is a schematic diagram which shows an example of a structure of the liquid crystal display device of embodiment by this invention. It is a figure which shows the viewing angle-contrast ratio characteristic of the liquid crystal display device of the Example by this invention.

Explanation of symbols

1 TFT (active matrix) substrate 2 Gate signal line 3 Source signal line 4 TFT
5 Drain electrode 6 Pixel electrode 7 Transparent electrode 8 Reflective electrode 9 Gate insulating film 10 Gate electrode 11 Source / drain electrode (n + -Si layer)
12 Semiconductor Layer 13 Channel Protection Layer 14 Opening Structure 15 Opening 16 Insulating Film 17 Transparent Substrate (Counter (CF) Substrate)
18 Color filter layer 19 Counter electrode 20 Liquid crystal layer 21 Liquid crystal molecule 22, 32 Alignment film 50 Liquid crystal panel 40, 43 Polarizing plate 41, 44 1/4 wavelength plate 42, 45 Retardation plate (NR plate) with negative optical anisotropy )
100, 100 'Transmission type liquid crystal display device 110a Active matrix substrate 110b Counter substrate (color filter substrate)
DESCRIPTION OF SYMBOLS 111 Pixel electrode 113 Notch part 114 Opening 115a Interlayer insulation film 115b Wall structure 130 Color filter layer 131 Counter electrode 133 Support body 200, 300 Transflective liquid crystal display device 210a Active matrix substrate 210b Counter substrate (color filter substrate)
211 Pixel electrode 213 Notch 214 Opening 215a Interlayer insulating film 215b Wall structure 230 Color filter layer 231 Counter electrode 232 Transparent dielectric layer (reflection step)
233 Support

Claims (22)

A first substrate, a second substrate provided to face the first substrate, a liquid crystal layer provided between the first substrate and the second substrate, and formed on the first substrate. The first electrode, the second electrode formed on the second substrate, the interlayer insulating film provided between the first electrode and the first substrate, and the interlayer insulating film are formed integrally. A wall structure,
Each includes a plurality of pixels including the first electrode, the second electrode, and the liquid crystal layer provided between the first electrode and the second electrode, and each of the periphery of the plurality of pixels. The liquid crystal display device has a light shielding region, and the wall structure is regularly arranged in the light shielding region.   2. The device according to claim 1, further comprising a plurality of switching elements electrically connected to the first electrode on the first substrate, wherein at least a part of the switching elements is covered with the interlayer insulating film. Liquid crystal display device.   The liquid crystal display device according to claim 1, wherein the first electrode included in each of the plurality of pixels includes a transparent electrode and a reflective electrode.   The liquid crystal display device according to claim 1, wherein the wall structure has an inclined side surface, and the first electrode extends to the side surface.   5. The liquid crystal layer according to claim 1, wherein the liquid crystal layer is a vertical alignment type liquid crystal layer, and forms at least one liquid crystal domain including liquid crystal molecules aligned in different directions when at least a predetermined voltage is applied. The liquid crystal display device described.   6. The liquid crystal display device according to claim 1, wherein the first electrode and / or the second electrode has a plurality of openings or notches formed at predetermined positions.   The liquid crystal display device according to claim 6, wherein the first electrode and / or the second electrode has at least two openings and at least one notch formed at predetermined positions.   The liquid crystal display device according to claim 6, wherein the plurality of openings or notches are formed only in the first electrode.   The liquid crystal layer is a vertical alignment type liquid crystal layer, and forms at least two liquid crystal domains each exhibiting axial symmetry when at least a predetermined voltage is applied, and the axial symmetry of each of the at least two liquid crystal domains. 9. The liquid crystal display device according to claim 6, wherein the central axis is formed in or near the plurality of openings.   The liquid crystal display device according to claim 1, wherein the wall structure has walls separated by a wall gap.   11. The liquid crystal display device according to claim 10, wherein a length of the wall gap existing around one pixel is 40% or less with respect to a length around the pixel.   The liquid crystal display device according to claim 1, wherein a support that regulates a thickness of the liquid crystal layer is regularly arranged in the light shielding region.   The liquid crystal display device according to claim 12, wherein the wall structure has walls separated by a wall gap, and the support is disposed in the wall gap. The diameter of the support is WL (μm), the number N of the support is arranged per regular unit (0.12 mm ² ), and the pitch in the long side direction of the plurality of pixels is PL (μm). In case,
14. The liquid crystal display device according to claim 12, wherein the arrangement density D defined by WL × N / PL satisfies a relationship of 0.01 ≦ D ≦ 0.3. The liquid crystal layer is a vertical alignment type liquid crystal layer, and forms at least one liquid crystal domain each exhibiting an axially symmetric alignment when at least a predetermined voltage is applied,
The wall structure has inclined side surfaces, and a cross-sectional shape of the wall structure and the interlayer insulating film in a plane perpendicular to the first substrate is formed by a central axis of an axially symmetric orientation of the at least one liquid crystal domain The liquid crystal display device according to claim 1, wherein the liquid crystal display device has a continuous shape with a region to be formed as a bottom.   The liquid crystal display device according to claim 1, wherein the wall structure has inclined side surfaces, and an inclination angle of the inclined side surfaces with respect to a surface of the first substrate is 45 ° or less.   A pair of polarizing plates arranged to face each other with the first substrate and the second substrate interposed therebetween, and at least between the first substrate and / or the second substrate and the pair of polarizing plates The liquid crystal display device according to claim 1, further comprising one biaxial optically anisotropic medium layer.   It further has a pair of polarizing plates arranged so as to face each other with the first substrate and the second substrate interposed therebetween, and between the first substrate and / or the second substrate and the pair of polarizing plates. The liquid crystal display device according to claim 1, further comprising at least one uniaxial optically anisotropic medium layer. A first substrate, a second substrate provided to face the first substrate, a liquid crystal layer provided between the first substrate and the second substrate, and formed on the first substrate. A first electrode; a circuit element electrically connected to the first electrode; a second electrode formed on the second substrate; and provided between the first electrode and the first substrate. An interlayer insulating film and a wall structure formed integrally with the interlayer insulating film, each of which is between the first electrode, the second electrode, and the first electrode and the second electrode. A method of manufacturing a liquid crystal display device, comprising: a plurality of pixels including the liquid crystal layer provided; a light shielding region around the plurality of pixels; and the wall structure regularly arranged in the light shielding region Because
Forming a circuit element on the first substrate;
Forming a positive photosensitive resin film covering the circuit element;
A step of exposing the photosensitive resin film, the step of forming predetermined regions having different exposure amounts;
Developing the exposed photosensitive resin film to form an interlayer insulating film having a contact hole exposing a part of the circuit element and integrally formed with the wall structure;
Forming a first electrode on the interlayer insulating film;
A method for manufacturing a liquid crystal display device. The step of forming the interlayer insulating layer includes a step of forming a first region having a substantially flat surface and a second region having a concavo-convex shape on the surface,
The step of forming the first electrode includes a step of forming a transparent electrode on the interlayer insulating film in the first region and a step of forming a reflective electrode on the interlayer insulating film in the second region. A method for manufacturing a liquid crystal display device according to claim 19. The exposure step uses a first photomask to form a region that becomes the wall structure and a region other than the first exposure step,
21. The method of manufacturing a liquid crystal display device according to claim 20, further comprising a second exposure step of forming the first region and the second region using a second photomask in the other region. The step of forming the first electrode and / or the second electrode includes a step of forming a conductive film and a step of patterning the conductive film. The step of patterning includes the first electrode and / or The method for manufacturing a liquid crystal display device according to claim 19, comprising a step of forming a plurality of openings or notches at predetermined positions of the second electrode.