JP4237977B2 - Liquid crystal display - Google Patents

Liquid crystal display Download PDF

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JP4237977B2
JP4237977B2 JP2002160758A JP2002160758A JP4237977B2 JP 4237977 B2 JP4237977 B2 JP 4237977B2 JP 2002160758 A JP2002160758 A JP 2002160758A JP 2002160758 A JP2002160758 A JP 2002160758A JP 4237977 B2 JP4237977 B2 JP 4237977B2
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liquid crystal
electrode
crystal display
display device
alignment
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JP2003177418A5 (en
JP2003177418A (en
Inventor
公昭 中村
雄一 井ノ上
洋平 仲西
貴啓 佐々木
善郎 小池
正和 柴崎
真吾 片岡
一孝 花岡
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シャープ株式会社
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate for a liquid crystal display whose optical transmittance is improved without any reduction in the response speed of the same at a transition between tones, and to provide a liquid crystal display using the same. <P>SOLUTION: The substrate for the liquid crystal is provided with a drain bus line 6 formed on an array substrate which holds liquid crystal with counter substrates disposed opposite to the array substrate, a TFT 16 connected to the drain bus line 6, and a stripe-shaped electrode 8 and a space 10 which are connected to the TFT 16 and arranged successively in parallel with the drain bus line 6. The substrate for the liquid crystal is further provided with a pixel electrode 3 in which a stripe-shaped electrode 8 in the vicinity of the drain bus line 6 is formed with an electrode with narrower than that of an electrode 12 located inside the same. <P>COPYRIGHT: (C)2003,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a substrate for a liquid crystal display device and a liquid crystal display device using the same, and in particular, a VA (Vertical Aligned) mode in which liquid crystal having negative dielectric anisotropy is vertically aligned, and a positive dielectric The present invention relates to a substrate for a liquid crystal display device such as an IPS (In-Plane-Switching) mode in which a liquid crystal having anisotropy is horizontally aligned and applies a lateral electric field, and a liquid crystal display device using the same.
In the present invention, a liquid crystal layer containing a polymerizable component (monomer or oligomer) that is polymerized by light or heat is sealed between substrates, and the voltage applied to the liquid crystal layer is adjusted (the applied voltage is 0 (zero). In the following cases, it is simply abbreviated as “applying voltage” depending on the case.) Polymerizable components are polymerized to give a very small tilt angle (so-called pretilt angle) with respect to the substrate interface. The present invention relates to a liquid crystal display device applied to a liquid crystal display device and a substrate for a liquid crystal slip device used therefor.
[0002]
[Prior art]
Multi-domain vertical alignment mode (Multi-domain) in which liquid crystal having negative dielectric anisotropy is vertically aligned and a bank (linear protrusion) or electrode extraction (slit) is provided on the substrate as an alignment regulating structure 2. Description of the Related Art A liquid crystal display device (hereinafter, abbreviated as MVA-LCD) is known. Since the alignment regulating structure is provided, the liquid crystal alignment azimuth during voltage application can be controlled to a plurality of azimuths without performing a rubbing treatment on the alignment film. This MVA-LCD is superior in viewing angle characteristics as compared with a conventional TN (twisted nematic) mode LCD.
[0003]
However, the conventional MVA-LCD has a drawback that white luminance is low and display is dark. The main reason for this is that the upper part of the protrusion and the upper part of the slit are the boundary of the alignment division and dark lines are generated, so that the transmittance at the time of white display is lowered and it looks dark. In order to remedy this drawback, the spacing between the protrusions and slits should be sufficiently wide. It takes time to stabilize, causing a problem that the response speed becomes slow.
[0004]
In order to improve this problem and obtain an MVA-LCD with high brightness and capable of high-speed response, it has been proposed to use a pretilt angle imparting technique using a polymer. In a pretilt angle providing technique using a polymer, a liquid crystal composition in which a polymerizable component such as a monomer or an oligomer (hereinafter abbreviated as a monomer) is mixed with liquid crystal is sealed between substrates. The monomer is polymerized by applying a voltage between the substrates and tilting the liquid crystal molecules. As a result, a liquid crystal layer that tilts at a predetermined pretilt angle even when voltage application is removed is obtained, and the liquid crystal orientation can be defined. As the monomer, a material that is polymerized by heat or light (ultraviolet rays) is selected.
[0005]
However, the pretilt angle imparting technique using a polymer has several problems related to display unevenness when an image is displayed on a completed LCD. First, there is a problem that display unevenness occurs in the image display of the completed LCD due to a liquid crystal alignment abnormality locally generated in liquid crystal driving during monomer polymerization.
[0006]
On the other hand, an IPS mode liquid crystal display device (hereinafter abbreviated as IPS-LCD) that applies a horizontal electric field by horizontally aligning liquid crystals having positive dielectric anisotropy has excellent viewing angle characteristics as well as MVA-LCD. Yes. However, in the IPS-LCD, liquid crystal molecules are switched in a horizontal plane by a comb-shaped electrode, and the aperture ratio of the pixel is remarkably reduced by the comb-shaped electrode, so that a backlight unit having a high light intensity is required.
[0007]
Although the decrease in the actual aperture ratio of the pixels due to the protrusions and slits in the MVA-LCD is not as high as that of the comb-shaped electrode of the IPS-LCD, the light transmittance of the panel is lower than that of the TN mode LCD. Therefore, at present, MVA-LCDs and IPS-LCDs are hardly employed in notebook computers that require low power consumption.
[0008]
The current MVA-LCD has a wide viewing angle, and a large number of slits with linear protrusions and pixel electrodes partially removed are arranged in the pixel so that liquid crystal molecules tilt in four directions when a voltage is applied. ing. For this reason, the light transmittance of a pixel becomes low.
[0009]
In order to improve this, an alignment regulating operation when the interval between adjacent linear protrusions is widened with a simple configuration will be described. FIG. 14 shows an MVA-LCD having a two-part alignment region. FIG. 14A shows a state where one pixel 2 of the MVA-LCD is viewed in the normal direction of the substrate surface. FIG. 14B shows a cross section obtained by cutting the MVA-LCD shown in FIG. 14A in parallel with the drain bus line 6. FIG. 14A shows three pixels 2 connected to one gate bus line 4. As shown in FIGS. 14A and 14B, two linear protrusions 68 extending in parallel to the gate bus line 4 are formed in the vicinity of both ends of the pixel electrode 3 on the gate bus line 4 side. . Also. On the counter substrate side common electrode, a linear protrusion 66 extending in parallel with the gate bus line 4 is formed at a position including the center of the pixel. On the array substrate side, an insulating film (gate insulating film) 23 is formed on the glass substrate 20 and the gate bus line 4, and an insulating film 22 is formed thereon.
[0010]
With this configuration, when a voltage is applied between the pixel electrode 3 and the common electrode 26 to change the electric field distribution in the liquid crystal layer 24, the liquid crystal molecules 24a having negative dielectric anisotropy are inclined in two directions. . That is, the liquid crystal molecules 24a are inclined from the linear protrusions 68 on both ends of the pixel 2 on the gate bus line 4 side toward the linear protrusions 66 on the counter substrate side. As a result, a multi-domain divided into upper and lower parts is formed. In the MVA mode, the inclination direction is sequentially defined from the liquid crystal molecules 24a in the vicinity of the linear protrusions 66 and 68 (or in the vicinity of the slit) by the electric field generated by the linear protrusion (or slit). Accordingly, when the gap between the linear protrusions (or slits) is very wide as shown in FIGS. 14A and 14B, it takes time to propagate the inclination of the liquid crystal molecules 24a. The response of the liquid crystal molecules becomes very slow.
[0011]
Accordingly, it is conceivable to adopt a pretilt angle imparting technique using a polymer. In the pretilt angle providing technique using a polymer, a monomer is polymerized and polymerized in a state where a voltage is applied to a liquid crystal layer 24 containing a polymerizable monomer instead of a conventional liquid crystal material, and the liquid crystal molecules 24a are inclined to the polymer. Remember direction.
[0012]
However, even if a voltage is applied to the liquid crystal layer 24 in the structure of FIGS. 14A and 14B, liquid crystal molecules in the vicinity of the drain bus line 6 are generated by an electric field generated at the end of the pixel electrode 3 in the vicinity of the drain bus line 6. 24a falls down in a direction different from the intended inclination direction by 90 °. For this reason, even if a pretilt angle providing technique using a polymer is used, each display pixel 2 has a light shielding film (BM) as shown in the pixel microscope observation view of the MVA-LCD in FIG. ) Protrudes and a large dark portion X1 is visually recognized along the drain bus line 6.
[0013]
In order to solve this problem, in the previous application by the present applicant (Japanese application number: Japanese Patent Application No. 2001-264117, application date: August 31, 2001), the pixel electrode on the array substrate side on which the TFT 16 is formed. 3 is proposed to be a stripe electrode having a line and space pattern. As an example, FIG. 16 shows an embodiment in which one pixel 2 of the MVA-LCD is viewed in the normal direction of the substrate surface. As shown in FIG. 16, the pixel electrode 3 has a striped electrode 8 and a space 10 in which a line and space pattern is formed in parallel to the drain bus line 6.
[0014]
In general, the alignment regulating force by the alignment film acts only on the liquid crystal molecules 24a in contact with the alignment film, and does not reach the liquid crystal molecules in the center portion in the cell gap direction. Therefore, the liquid crystal molecules 24a in the center part in the cell gap direction are greatly affected by the electric field generated at the pixel end part, and the orientation direction is disturbed. When the pixel electrode 3 having the stripe-shaped electrode 8 and the space 10 parallel to the drain bus line 6 is used, the liquid crystal molecules 24a fall in parallel to the stripe-shaped electrode 8 and the space 10 when a voltage is applied. Further, since the tilt direction of all the liquid crystal molecules 24a is determined by the stripe-shaped electrodes 8 and the spaces 10, the influence of the lateral electric field generated at the pixel end can be minimized.
[0015]
The liquid crystal display device proposed in the above application and the manufacturing method thereof will be specifically described below. 16 shows a state in which one pixel 2 of the proposed MVA-LCD is viewed in the normal direction of the substrate surface, and FIG. 17 shows a cross-sectional shape cut along the line DD in FIG. As shown in FIG. 16, the pixel electrode 3 has a striped electrode 8 and a space 10 in which a line and space pattern is formed in parallel to the drain bus line 6. Each striped electrode 8 is electrically connected by a connection electrode 64 formed substantially in the center of the pixel 2 and parallel to the gate bus line 4. A part of the striped electrode 8 is connected to a source electrode 62 disposed opposite to the drain electrode 60 of the TFT 16.
[0016]
As shown in FIG. 17, linear protrusions 66 extending in parallel with the gate bus lines 4 are formed on the counter substrate side at positions facing the connection electrodes 64 in the center of the pixel region. The alignment protrusion direction of the liquid crystal molecules 24a can be more significantly determined by the linear protrusions 66.
[0017]
Of course, a rubbing treatment may be applied to the alignment film on the array substrate side or the counter substrate side instead of providing the linear protrusion 66 on the counter substrate side. In this case, as indicated by the arrows shown in FIG. 17, the array substrate side is rubbed toward the connection electrode 64 in both regions B and C shown in FIG. The counter substrate side is rubbed in a direction away from the connection electrode 64. It is also possible to use a photo-alignment method.
[0018]
Using the panel structure shown in FIGS. 16 and 17, a voltage is applied to the liquid crystal layer 24 to which the photopolymerizable monomer is added, and the liquid crystal layer 24a in the pixel 2 is tilted in a predetermined direction. The pre-tilt angle and / or orientation direction of the liquid crystal molecules 24a were defined by polymerizing the monomer by irradiating light. When the completed MVA-LCD was displayed and the display area was observed, the dark portion X1 disappeared and light was transmitted from the entire pixel portion, and the transmittance was improved as compared with the conventional case.
[0019]
[Problems to be solved by the invention]
However, in the structure proposed in the above application, although the alignment of the liquid crystal layer can be defined, the liquid crystal molecules on the space 10 are not sandwiched between the upper and lower electrodes, and no direct electric field is applied. Do not (do not fall). For this reason, the problem that the transmittance | permeability falls in the space 10 vicinity arises. For this reason, the structure shown in FIG. 16 can regulate liquid crystal alignment more than the structure shown in FIG. 14, while improving the transmittance without generating the dark portion X1 in the pixel peripheral portion as shown in FIG. However, the light transmittance inside the peripheral portion of the pixel is conversely reduced, and there is a problem that the transmittance of the entire pixel cannot be drastically improved.
[0020]
An object of the present invention is to provide a substrate for a liquid crystal display device in which the light transmittance is improved without reducing the response speed at the time of gradation change, and a liquid crystal display device using the same.
[0021]
[Means for Solving the Problems]
  The above purpose isA pair of substrates disposed opposite to each other, a liquid crystal sandwiched between the pair of substrates, and stripe electrodes and spaces periodically arranged in different directions for each predetermined region on the one substrate, The liquid crystal display device is characterized in that at least one of the electrode width of the stripe-shaped electrode and the space width of the space is different between the vicinity of the predetermined region and the portion other than the vicinity of the boundary.Achieved by:
[0022]
DETAILED DESCRIPTION OF THE INVENTION
[First Embodiment]
A substrate for a liquid crystal display device according to a first embodiment of the present invention and a liquid crystal display device using the same will be described with reference to FIGS. In the pixel electrode 3 of the liquid crystal display device according to the present embodiment, striped electrodes 8 and spaces 10 are formed in parallel with the drain bus lines 6 or the gate bus lines 4. However, the electrode width of the striped electrode 8 in the vicinity of the bus line is formed to be narrower than the width of the inner electrode. In addition, the total area of the space 10 is 50% or less of the total area of the pixel electrode 3 (total area of the electrode region), which is the sum of the total area of the space 10 and the total area of the striped electrodes 8 and other electrodes. It has characteristics.
[0023]
Further, when the two-way orientation is performed in the extending direction of the drain bus line 6, the stripe-shaped electrode 8 is provided only in the peripheral portion of the pixel on the drain bus line 6 side and the two-way alignment is performed in the extending direction of the gate bus line 4. Is characterized in that the striped electrodes 8 are provided only in the vicinity of the pixels on the gate bus line 6 side and in the vicinity of the alignment division boundary.
[0024]
The principle for determining the structure of the pixel electrode 3 according to this embodiment will be described with reference to FIGS. FIG. 1 shows a partial cross section of a VA-LCD cut perpendicularly to the substrate surface. In FIG. 1, a pixel electrode 3 is formed on a glass substrate 20 which is an insulating substrate on the array substrate side on which switching elements such as TFTs are formed. The pixel electrode 3 is a combination of the striped electrode 8 and the space 10, and the striped electrode 8 and the space 10 are alternately formed in a region not shown in the left-right direction in the drawing. In this example, the width L of the stripe electrode 8 is 3 μm and the width S of the space 10 is 3 μm. A common electrode 26 is formed on the side surface of the liquid crystal layer of the counter substrate side glass substrate 30 that is disposed opposite to the array substrate side glass substrate 20 and sandwiches the liquid crystal layer 24.
[0025]
A vertical alignment film (not shown) is formed at the interface between the glass substrates 20 and 30 and the liquid crystal layer 24. The liquid crystal layer 24 includes a liquid crystal material having negative dielectric anisotropy to which a photopolymerizable monomer is added.
[0026]
In the VA-LCD having such a configuration, when a voltage is applied between the stripe electrode 8 and the common electrode 26 to change the electric field strength to the liquid crystal molecules 24a in the liquid crystal layer 24, the electric field strength is changed. The transmittance can be changed by changing the tilt angle of the liquid crystal molecules 24a.
[0027]
FIG. 2 is a graph showing a change in transmittance with respect to a change in applied voltage between the striped electrode 8 and the common electrode 26. The horizontal axis shows the arrangement positions of the striped electrodes 8 and the spaces 10 in the left-right direction of the glass substrate 20 of the VA-LCD shown in FIG. The vertical axis represents the transmittance. In the figure, a continuous curve indicated by ◆ indicates a transmittance distribution at an applied voltage of 3V. A curve indicated by continuous Δ marks indicates a transmittance distribution at an applied voltage of 3.5V. A continuous curve indicated by x indicates a transmittance distribution at an applied voltage of 4V. A continuous curve indicated by □ indicates a transmittance distribution at an applied voltage of 5.4V. A continuous curve indicated by-(solid line) indicates a transmittance distribution at an applied voltage of 10V. In either case, the transmittance distribution is shown when 500 ms elapses after voltage application.
[0028]
As shown in FIG. 2, as the applied voltage is increased, the transmittance increases correspondingly. In either case, the curve has a maximum value at the center of the striped electrode 8 and a minimum value at the center of the space 10. Become. That is, as shown in FIG. 1, when the pixel electrode 3 is formed of a combination of the striped electrode 8 and the space 10, there is a difference between the electric field strength above the stripe electrode 8 and the electric field strength above the space 10 when a voltage is applied. Since the electric field strength above the space 10 is relatively low, the transmittance is reduced in the vicinity of the space 10. Thereby, even if the dark portion X1 at the peripheral edge of the pixel electrode 3 near the drain bus line 6 disappears, the overall transmittance does not increase. For example, in FIG. 2, the average transmittance at an applied voltage of 5.4 V indicated by the □ mark curve is 0.784, whereas that of the pixel electrode 3 having a “solid” structure without a space 10 described later is The brightness is 0.897 (see FIG. 4), and the “solid” structure can obtain higher brightness with a brightness difference of about 14% (0.897 / 0.784 = 1.14).
[0029]
FIG. 3 shows a VA-LCD having the same configuration as that of FIG. 1 except that the pixel electrode 3 is uniformly formed in each pixel region. FIG. 4 is a graph showing a change in transmittance with respect to a change in applied voltage between the pixel electrode 3 and the common electrode 26. The horizontal axis corresponds to the left-right direction of the glass substrate 20 of the VA-LCD shown in FIG. 3, and shows the pixel electrode 3 in the central portion of the pixel region. The vertical axis represents the transmittance. In the figure, a continuous curve indicated by ◆ indicates a transmittance distribution at an applied voltage of 3V. A continuous curve indicated by □ indicates a transmittance distribution at an applied voltage of 5.4V. A continuous curve indicated by-(solid line) indicates a transmittance distribution at an applied voltage of 10V. In either case, the transmittance distribution is shown when 500 ms elapses after voltage application.
[0030]
As shown in FIG. 4, as the applied voltage is increased, the transmittance increases accordingly. However, regardless of the magnitude of the applied voltage, any transmittance distribution is flat and no change depending on the substrate position is observed. That is, as shown in FIG. 3, when the pixel electrode 3 has a “solid” structure without the space 10, since the electric field strength at the time of voltage application is flat at the center of the pixel electrode 3, uniform transmittance can be obtained. It is done.
[0031]
However, as already described with reference to FIGS. 14 and 15, when the pixel electrode 3 has a “solid” structure without the space 10, the dark portion X <b> 1 is formed at the peripheral edge of the pixel electrode 3 near the drain bus line 6. As a result, the transmittance of the pixel is lowered as a whole.
[0032]
That is, when the proportion of the space 10 in the pixel electrode 3 is increased, the alignment state of the liquid crystal layer 24 is improved, but the transmittance is not significantly increased. On the other hand, when the proportion of the space 10 becomes too small, the alignment disorder of the liquid crystal layer 24 increases and the transmittance decreases.
[0033]
That is, if the total area of the space 10 has an optimal ratio with respect to the total area of the space 10 and the striped electrodes 8 and other electrodes, that is, the total area of the pixel electrode 3, the transmittance is maximized. be able to. As a result of intensive experiments, it has been found that when the proportion of the space 10 is 4 to 50%, the alignment state of the liquid crystal layer 24 is improved and high transmittance can be obtained.
[0034]
In addition, in order to suppress the occurrence of the dark portion X1, in the case of two-orientation orientation in the extending direction of the drain bus line 6, at least the striped electrode 8 is provided in the pixel peripheral portion on the drain bus line 6 side, and the gate bus line 4 In the case of two-divided alignment in the extending direction, the striped electrode 8 may be provided at least near the pixel peripheral portion on the gate bus line 4 side and in the vicinity of the alignment division boundary.
[0035]
The liquid crystal display device according to the present embodiment will be specifically described below using examples. First, conditions common to all the following examples are listed below.
Alignment film: vertical alignment film;
Liquid crystal: has negative dielectric anisotropy and has a photopolymerizable monomer added;
Polarizing plate: arranged in crossed Nicols on both sides of the liquid crystal panel to achieve normally black mode;
Polarization axis of polarizing plate: 45 ° direction with respect to bus line;
LCD panel: diagonal 15 inches;
Resolution: XGA.
[0036]
[Example 1-1]
The present embodiment will be described with reference to FIGS. FIG. 5 shows an array substrate in which one pixel 2 of the MVA-LCD according to the present embodiment is viewed in the normal direction of the substrate surface, and FIG. 6 shows a cross-sectional shape of the LCD cut along the line AA in FIG. As shown in FIG. 5, the pixel electrode 3 has the inner electrode 12 in which the space 10 is not formed and the electrode material is uniformly formed inward from the periphery of the pixel region. Further, the pixel electrode 3 is at both ends parallel to the drain bus line 6, and is adjacent to the four spaces 10 formed on the upper and lower sides of the connection electrode 64 and the inner electrode 12 via each space 10. There are four matching striped electrodes 8. Each striped electrode 8 is electrically connected to the inner electrode 12 by a connection electrode 64 formed substantially at the center of the pixel 2 when viewed in the vertical direction. The upper left portion of the inner electrode 12 is connected to the source electrode 62 of the TFT 16.
[0037]
In this embodiment, the width L of the stripe electrode 8 is 3 μm and the width S of the space 10 is 3 μm. Further, the total area of the space 10 in this embodiment is 6% with respect to the total area of the pixel electrode 3 which is the total area of the space 10 and the stripe-shaped electrode 8 and other electrodes (inner electrode 12 and connection electrode 66). Have a ratio of
[0038]
As shown in FIG. 6, linear protrusions 66 extending in parallel with the gate bus lines 4 are formed on the counter substrate side at positions facing the connection electrodes 64 in the center of the pixel region. The alignment protrusion direction of the liquid crystal molecules 24a can be more significantly determined by the linear protrusions 66.
[0039]
Of course, a rubbing treatment may be applied to the alignment film on the array substrate side or the counter substrate side instead of providing the linear protrusion 66 on the counter substrate side. In this case, as indicated by the arrow shown in FIG. 6, the regions B and C shown in FIG. 5 are rubbed toward the center of the pixel electrode 3 in parallel with the drain bus line 6 on the array substrate side. The counter substrate side is rubbed in a direction away from the connection electrode 64. It is also possible to use optical (UV) orientation.
[0040]
By the way, there is a case where the alignment disorder occurs in which the tilt direction of the liquid crystal molecules 24b in the region A surrounded by the broken line near the TFT 16 shown in FIG. 5 is opposite to the liquid crystal molecules 24a in the region B as shown in FIG. . Due to this alignment disorder, a dark portion is formed in the region A when a voltage is applied to the liquid crystal layer 24. A modification for improving this is shown in FIG. In the modification, as shown in FIG. 7, two linear protrusions 68 extending in parallel to the gate bus line 4 are formed as alignment regulating structures in the vicinity of both ends of the pixel electrode 3 on the gate bus line 4 side. . If the linear protrusion 68 is added on the gate bus line and between the gate bus line 4 and the pixel electrode 3, the liquid crystal molecules 24b in the region A can be tilted in the same direction as the liquid crystal molecules 24a in the region B. . In addition, it is also possible to use the electrode extraction part (slit) which does not form a part of electrode as a structure for orientation control.
[0041]
7 is applied to the liquid crystal layer 24 using the structure according to the modification (gate electrode: DC 30 V, drain electrode: DC-5 V, common electrode: ground potential) so that the liquid crystal molecules 24 a in the pixel 2 are directed in a predetermined direction. In a tilted state, the liquid crystal added with the photopolymerizable monomer was irradiated with light to polymerize the monomer, thereby defining the pretilt angle and / or orientation direction of the liquid crystal molecules 24a. When the completed MVA-LCD was displayed and the display area was observed, light was transmitted from the entire pixel portion, and the transmittance was improved as compared with the conventional LCD.
[0042]
As described above, according to this embodiment, when the drain bus line 6 is divided into two in the extending direction, the striped electrodes 8 are provided in the peripheral portions of both pixels on the drain bus line 6 side, and the ratio of the space 10 is occupied. Therefore, the alignment state of the liquid crystal layer 24 is improved and high transmittance can be obtained.
[0043]
[Example 1-2]
The present embodiment will be described with reference to FIG. FIG. 8 shows the array substrate side when one pixel 2 of the MVA-LCD according to the present embodiment is viewed in the normal direction of the substrate surface. This example has the same configuration as that of Example 1-1 except for the pixel electrode 3 structure. In contrast to the pixel electrode 3 structure shown in FIG. 5 of Example 1-1, the pixel electrode 3 of this example has both ends parallel to the drain bus line 6 and connection electrodes as shown in FIG. A total of eight spaces 10 are formed on each of the upper and lower sides of 64, and a total of eight stripe electrodes 8 are formed on each of the two spaces 10 adjacent to the inner electrode 12.
[0044]
Since the total area of the space 10 in this embodiment is twice that of the embodiment 1-1, it has an occupation ratio of 12% with respect to the total area of the pixel electrode 3.
[0045]
As described above, also in this embodiment, in the case where the drain bus line 6 is divided into two in the extending direction, a plurality of the striped electrodes 8 are provided in the periphery of both pixels on the drain bus line 6 side, and the ratio of the space 10 is occupied. Therefore, the alignment state of the liquid crystal layer 24 is improved and high transmittance can be obtained.
[0046]
[Example 1-3]
The present embodiment will be described with reference to FIG. FIG. 9 shows an array substrate in which one pixel 2 of the MVA-LCD according to this embodiment is viewed in the normal direction of the substrate surface. This example has the same configuration as that of Example 1-1 except for the pixel electrode 3 structure. In contrast to the pixel electrode 3 structure shown in FIG. 5 of Example 1-1, the pixel electrode 3 of this example has a lower height in the extending direction of the drain bus line 6 of the inner electrode 12 of FIG. The inner electrode 12 ′ is characterized in that a line-and-space stripe electrode 8 ′ and a space 10 ′ are provided in a region where the height is lowered.
By adopting this structure, the total area of the spaces 10 and 10 ′ in this embodiment has an occupation ratio of 35% with respect to the total area of the pixel electrode 3.
[0047]
As described above, also in this embodiment, in the case where the drain bus line 6 is divided into two in the extending direction, a plurality of the striped electrodes 8 are provided in the periphery of both pixels on the drain bus line 6 side, and the ratio of the space 10 is occupied. Therefore, the alignment state of the liquid crystal layer 24 can be improved and high transmittance can be obtained.
[0048]
[Example 1-4]
The present embodiment will be described with reference to FIGS. FIG. 10 shows an array substrate in which one pixel 2 of the MVA-LCD according to this embodiment is viewed in the normal direction of the substrate surface. The structure of the pixel electrode 3 according to this embodiment is characterized in that the striped electrodes 8 and the spaces 10 are formed in parallel to the gate bus lines 4. In order to perform alignment division in two directions in the left and right directions in the figure, one stripe electrode 8 in the upper half of the pixel connected to the source electrode 62 of the TFT 16 is connected to the upper side of the figure by a connection electrode 64a on the upper right side of the figure through a space 10. One stripe-like electrode 8 in the lower half of the pixel is connected to the inner electrode 12b on the lower side of the drawing via a connection electrode 64d on the lower left side of the drawing. The inner electrode 12a is connected to the stripe-shaped electrode 8 'provided with the space 10 on both sides by the right connection electrode 64b, and the inner electrode 12b is connected by the left connection electrode 64c.
[0049]
By doing so, it is possible to positively utilize the alignment of the liquid crystal molecules inclined in the direction perpendicular to the drain bus line 6 by the lateral electric field generated at the pixel electrode end parallel to the drain bus line 6. It should be noted that the connection electrodes 64a to 64d may be of a pixel electrode 3 structure that is opposite to the left and right in FIG. With this structure, the total area of the space 10 in this embodiment is 4% of the total area of the pixel electrode 3.
[0050]
As described above, in this embodiment, in order to perform the two-divided alignment in the extending direction of the gate bus line 4, at least the stripe electrode 8 is provided in the peripheral portion of the pixel on the gate bus line 4 side and the stripe electrode 8 ′ is aligned with the alignment division boundary. Since it is provided in the vicinity (position where the two inner electrodes 12, 12 ′ face each other) and the ratio of the space 10 is 4%, the alignment state of the liquid crystal layer 24 can be improved and high transmittance can be obtained. .
[0051]
FIG. 11 shows a cross section taken along line BB in FIG. FIG. 12 shows a cross section cut along the line CC in FIG. As shown in FIGS. 11 and 12, linear protrusions 66 are formed on the counter substrate between the connection electrodes 64a and 64d and the drain bus line 6 adjacent thereto. By forming the linear protrusion 66, it is possible to eliminate the influence of the electric field between the ends of the inner electrodes 12, 12 ′ on the connection electrodes 64a, 64d side and the drain bus line 6 adjacent thereto. Further, in order to ensure the orientation direction, rubbing treatment or photo-alignment treatment may be performed.
[0052]
FIG. 13 shows a modification of this embodiment. As shown in FIG. 13, linear protrusions 68 may be formed on the array substrate near the left end of the inner electrode 12 in the drawing and near the right end of the inner electrode 12 ′ in the drawing. By forming the linear protrusion 68, the influence of the electric field between the vicinity of the left end of the inner electrode 12 in the drawing and the vicinity of the right end of the inner electrode 12 'in the drawing and the drain bus line 6 adjacent thereto is affected. Can be eliminated.
[0053]
In this configuration, a voltage is applied to the liquid crystal layer 24 to polymerize the monomers in the liquid crystal layer 24. The completed MVA-LCD is hardly affected by the electric field generated at the pixel end during image display because the direction in which the liquid crystal molecules 24a are tilted is determined by the polymerized polymer. When the display area was observed by displaying the MVA-LCD, light was transmitted from the entire pixel portion, and the transmittance was improved as compared with the conventional LCD.
[0054]
[Second Embodiment]
Next, a liquid crystal display device substrate and a liquid crystal display device using the same according to a second embodiment of the present invention will be described with reference to FIGS. First, as described with reference to FIG. 5 in the first embodiment, in a region A surrounded by a broken line indicating a connection portion between the source electrode 62 and the stripe electrode 8 of the TFT 16, the liquid crystal molecules 24 b are tilted in the reverse direction. Therefore, a dark line is generated at the boundary with the liquid crystal molecules 24a that fall in the positive direction. This phenomenon also occurs in the proposed pixel electrode structure shown in FIGS. 16 and 17 (see liquid crystal molecules 24b in FIG. 17). In the first embodiment, the generation of dark lines is suppressed by providing the linear protrusions 68 on the array substrate side. Here, the state in the case where the linear protrusions 68 are not provided will be further considered.
[0055]
In the case where the linear protrusion 68 is not provided, there is no electric field that defines the position where the dark line is generated, so that the region of the liquid crystal molecules 24b tilted in the reverse direction can be arbitrarily expanded. For this reason, the liquid crystal molecules 24a ′ (not shown) that fall in the direction perpendicular to the bus lines in the vicinity of the drain bus lines 6 are pulled out from the BM region to the display region side, and the region where the liquid crystal molecules 24a ′ exist is the drain bus lines. 6 and the pixel peripheral portion. Therefore, the dark line X1 outside the display area in the vicinity of the drain bus line 6 swells, and the dark line X1 appears in the vicinity of the drain bus line 6 in the display area as shown in the pixel microscope observation view of FIG.
[0056]
In the present embodiment, in order to solve the above problem, the liquid crystal molecules 24b that fall in the reverse direction in the vicinity of the connection portion between the source electrode 62 and the stripe electrode, and the direction orthogonal to the drain bus line 6 in the vicinity of the drain bus line 6 The liquid crystal molecules 24a that fall over are not affected by each other.
[0057]
The liquid crystal display device according to the present embodiment will be specifically described below using examples.
[Example 2-1]
This embodiment will be described with reference to FIG. FIG. 19A shows a state in which one pixel 2 of the MVA-LCD having a two-divided alignment region is viewed in the normal direction of the substrate surface. FIG. 19B is a pixel microscope observation view in which the MVA-LCD is viewed in the normal direction of the substrate surface. As shown in FIG. 19A, in this embodiment, one striped electrode 9 and a space 10 are formed between the drain bus line 6 and the TFT 16.
[0058]
In addition, in order to prevent the liquid crystal molecules 24b from falling in the reverse direction, the stripe electrode 8 at the center of the connection portion is cut at the connection portion side at the connection portion between the source electrode 62 and the stripe electrode 8 of the TFT 16 so that the source electrode A gap 11 is formed between 62 and the end of the striped electrode 8.
[0059]
When at least one stripe electrode 9 and a space 10 are formed between the drain bus line 6 and the TFT 16, the stripe electrode 9 causes the liquid crystal molecules 24 a in the vicinity of the drain bus line 6 on the pixel electrode 3 to form the space 10. Falls in a direction parallel to the longitudinal direction of Thereby, it is possible to prevent the liquid crystal molecules 24 a falling in the direction perpendicular to the drain bus line 6 and the alignment of the liquid crystal molecules 24 b falling in the reverse direction near the source electrode 62 of the TFT 16 from affecting each other. For this reason, the dark line X1 in the vicinity of the drain bus line 6 can be kept on the BM outside the display area.
[0060]
Further, by cutting at least one portion of the striped electrode 8 at the connection portion between the source electrode 62 of the TFT 16 and the pixel electrode 3 to form the gap 11, the same effect as that of forming a new end of the striped electrode 8 is obtained. Therefore, the generation of the dark line X1 can be minimized, and the generation position can be fixed to the BM outside the display area.
[0061]
Since the dark line X1 is often generated with a bead spacer or the like that maintains the cell gap between the substrates as a nucleus, it is desirable to replace the gap-exposing spacer with a columnar spacer and arrange it outside the display area.
[0062]
If the width L of the striped electrodes 8 and 9 is too thin, the stripe electrodes 8 and 9 may be cut. If the width L is too thick, the liquid crystal molecules 24a will not fall in parallel with the longitudinal direction of the space 10. If the width S of the space 10 is too narrow, the striped electrodes 8 and 9 may be short-circuited. If the width S is too wide, the liquid crystal molecules 24a will not fall down in the longitudinal direction of the space 10. Therefore, it is desirable to set the width L of the stripe electrodes 8 and 9 and the width S of the space 10 to 0.5 μm or more and 5 μm or less.
Similarly, it is desirable that the width of the gap 11 (the distance between the end portion of the source electrode 62 and the end portion of the striped electrode 8 opposed thereto) is set to 0.5 μm or more and 5 μm or less.
[0063]
In this example and the following examples, a vertical alignment film is used, the liquid crystal has a negative dielectric anisotropy, and the polarizing plate is attached to both sides of the liquid crystal panel in a crossed Nicol state. The polarization axis is at 45 ° with respect to the bus line. The panel size is 15 inches and the resolution is XGA.
[0064]
[Example 2-2]
This embodiment will be described with reference to FIG. FIG. 20A shows a state in which one pixel 2 of the MVA-LCD having a two-divided alignment region is viewed in the normal direction of the substrate surface. FIG. 20B is a pixel microscope observation view in which the MVA-LCD is viewed in the normal direction of the substrate surface. As shown in FIG. 20A, in this embodiment, a single striped electrode 9 and a space 10 are formed between the drain bus line 6 and the TFT 16 as in the case of the embodiment 2-1.
[0065]
In addition, in order to prevent the liquid crystal molecules 24b from falling in the opposite direction, at the connection portion between the source electrode 62 and the stripe electrode 8 of the TFT 16, the two stripe electrodes 8 on both sides of the connection portion are cut at the connection portion side. The two gaps 11a and 11b are formed between the source electrode 62 and the end of the striped electrode 8.
[0066]
Even in such a configuration, the stripe-shaped electrode 9 causes the liquid crystal molecules 24 a in the vicinity of the drain bus line 6 on the pixel electrode 3 to fall in a direction parallel to the longitudinal direction of the space 10. Thereby, the alignment of the liquid crystal molecules 24a that are tilted in the direction orthogonal to the drain bus line 6 and the liquid crystal molecules 24b that are tilted in the reverse direction in the vicinity of the source electrode 62 of the TFT 16 can be prevented from affecting each other.
[0067]
Further, by forming the gaps 11a and 11b, it is possible to obtain the same effect as when two new stripe electrode 8 ends are formed, so that the generation of the dark line X1 can be minimized and the generation thereof. The position can be fixed to the BM outside the display area.
[0068]
Also in this embodiment, as in the case of Example 2-1, it is desirable to dispose columnar spacers for maintaining the cell gap outside the display area. The width L of the striped electrodes 8 and 9 and the width S of the space 10 are preferably set to 0.5 μm or more and 5 μm or less. Similarly, it is desirable that the widths of the gaps 11a and 11b are set to 0.5 μm or more and 5 μm or less.
[0069]
[Third Embodiment]
Next, a liquid crystal display device substrate and a liquid crystal display device using the same according to a third embodiment of the present invention will be described with reference to FIGS. FIG. 21 schematically shows a cross section of the MVA-LCD according to the present embodiment cut in a direction perpendicular to the substrate surface. FIGS. 22 to 26 are schematic views showing states in the vicinity of the alignment film 32. As shown in FIGS. 21 and 22, a polymer layer 36 is formed on alignment films 32 and 34 provided on the pixel electrode 3 and the common electrode 26, respectively. 23, the molecular orientation of the polymer in the polymer layer 36 is vertical on the surface of the vertical alignment film and is inclined in the direction of θp on the liquid crystal surface.
[0070]
As described above, the polymer layer 36 defines the alignment direction of the liquid crystal molecules 24a in the gap between the linear protrusions 66 and 68 which are the alignment regulating structure shown in FIG. That is, since the alignment direction of the liquid crystal molecules 24a is also defined between the structures, the response time in halftone display can be shortened, and further, the liquid crystal alignment disorder is reduced, so that the transmittance can be improved.
[0071]
The liquid crystal display device according to this embodiment will be specifically described below with reference to FIGS.
In FIG. 21, the pixel electrode 3 and the common electrode 26 are formed of a transparent pixel electrode material such as ITO. On the pixel electrode 3 and the common electrode 26, linear protrusions (bank-like orientation regulating structures) 66 and 68 having a height of 1.5 μm and a width of 10 μm are formed. The gap between the linear protrusions 66 and 68 is 25 μm. Vertical alignment films 32 and 34 are formed on the pixel electrode 3 and the common electrode 26 and on the linear protrusions 66 and 68, respectively. A negative liquid crystal layer 24 having a thickness of about 4 μm is sealed between the opposing vertical alignment films 32 and 34. As shown in the figure, the liquid crystal molecules 24a are inclined in the θp direction. The surfaces of the vertical alignment films 32 and 34 are not subjected to any rubbing treatment or optical alignment treatment.
[0072]
FIG. 22 shows a state in which the polymer layer 36 is formed on the vertical alignment film 32. Although not shown, a similar polymer layer 36 is also formed on the vertical alignment film 34 on the counter substrate side. FIG. 23 shows a state in which a polymer layer 36 that imparts a pretilt to the liquid crystal molecules 24 a at an angle θp is formed on the surface of the vertical alignment film 32 on the liquid crystal layer 24 side. As shown by the curve 38 indicating the change in the orientation direction, the polymer in the polymer layer 36 is tilted on the outermost surface in contact with the liquid crystal layer 24, and a pretilt is given to the liquid crystal molecules 24 a by the gap between the linear protrusions 66 and 68. It becomes possible to do. As shown in FIG. 23, the surface energy of the polymer increases due to the undulations on the surface of the polymer layer 36. When the thickness of the polymer layer 36 is greater than 5000 mm, the voltage drop at the polymer layer 36 increases, so the driving voltage becomes high and is not practical. Conversely, when the thickness is less than 10 mm, sufficient alignment regulating force cannot be obtained.
[0073]
In the polymer layer 36 shown in FIG. 23, 0.3 wt% of a monomer having an acryloyl group and a liquid crystal skeleton is added to a negative liquid crystal together with a polymerization initiator, and an illuminance of 20 mW / cm is applied while applying a voltage.2It is formed by polymerization with 2J UV light or the like. When a vertically-aligned polyimide film was used for the alignment film 32, it was confirmed by AFM (Atomic Force Microscope) and TEM that a polymer layer 36 having a thickness of about 100 mm was formed on the surface of the vertical alignment film 32. When the retardation (Δn · d) of the polymer was actually measured with an ellipsometer, it was found that the polymer was aligned in the liquid crystal alignment direction, and stable liquid crystal alignment at 0.01 nm or more was confirmed.
[0074]
FIG. 24 is a schematic view showing a state in which the polymer layer 36 is partially formed. As described above, when the amount of added monomer is small (about 0.5 wt% or less), or when it is solidified slowly (about 50 mW / cm2Lamination of the polymer layer on the alignment film or partial lamination can be realized on the following UV light source). Furthermore, by polymerizing while applying an electric field, the polymer can be aligned in the liquid crystal direction and can have retardation. And the provision of this retardation realizes tilted liquid crystal alignment. In addition, when the amount of monomer is large, a network polymer may be mixed.
[0075]
FIG. 25 shows a polymer layer 36 formed when the alignment films 32 and 34 are horizontal alignment films. It is formed by adding a monomer to a positive type liquid crystal and polymerizing while applying a voltage. Alternatively, it can be realized by forming a side chain in the monomer. 25, the molecular orientation of the polymer in the polymer layer 36 is horizontal on the surface of the horizontal alignment film 32 and is inclined in a predetermined angle direction on the surface of the liquid crystal layer 24. A pretilt is imparted to the polymer, and the entire liquid crystal tilts on average.
[0076]
FIG. 26 shows a state in which a film-like polymer layer 36 is formed on the horizontal alignment film 32. As shown by a curve 38 indicating a change in the orientation direction, the molecular orientation of the polymer in the polymer layer 36 polymer can be horizontal on the horizontal alignment film surface and substantially vertical on the liquid crystal surface. This polymer layer 36 can also be realized by polymerizing monomers on the horizontal alignment film 32. Or it can implement | achieve by forming a side chain in a monomer.
[0077]
In this embodiment, linear protrusions are used as the alignment regulating structure, but it is of course possible to use partition walls, slits, fine slits, rubbing alignment films, and the like. Even without using an alignment film, it is possible to form a polymer layer on a substrate having a vertical or horizontal alignment property. The polymer layer according to the present embodiment can also be applied to stabilization of the alignment of ferroelectric liquid crystal using smectic liquid crystal.
[0078]
As described above, according to the present embodiment, a polymer layer that defines the alignment direction can be formed between localized alignment regulating structures, so that liquid crystal can be stably aligned over the entire surface of the substrate. Therefore, the halftone response time can be shortened, and a high transmittance can be realized.
[0079]
[Fourth Embodiment]
Next, a liquid crystal display device substrate and a liquid crystal display device using the same according to a fourth embodiment of the present invention will be described with reference to FIGS. Prior to describing this embodiment, the prerequisite technology will be described. In the previous application by the applicant of the present application (Japanese application number: Japanese Patent Application No. 2001-264117, filing date: August 31, 2001), the pixel electrode 3 on the array substrate side on which the TFT 16 is formed is connected to the line and space. It has been proposed to form a patterned striped electrode. 27 and 28 show the orientation control means proposed in the previous application. As shown in FIG. 27 and FIG. 28, the liquid crystal molecules 24 a are arranged in the longitudinal direction of the stripe electrode 8 or the space 10 by using the stripe electrode 8 and the space 10 formed by repeating stripes of several μm width provided on the substrate. A configuration is proposed in which the alignment division boundaries in the pixel are reduced as much as possible by aligning them in parallel.
[0080]
In this case, the TV characteristics (applied voltage versus transmittance characteristics) of the liquid crystal display device change due to slight variations in the electrode width L of the striped electrode 8 due to variations in the photolithography process, which appear as display unevenness. It is known that there is a problem. In the previous application, it has been proposed to solve this problem as the electrode width L of the striped electrode 8 ≧ the width S of the space 10.
[0081]
In order to control the liquid crystal alignment in a plurality of directions in a panel using the striped electrodes 8 and the spaces 10, for example, as shown in FIGS. 29 and 30, the striped electrodes 8 and the spaces 10 oriented in a plurality of directions. It is necessary to use a (fish-bone-like) pattern in combination. At this time, paying attention to the boundary part (spine part) between the stripe electrode 8 and the space 10, the result of investigating the orientation state with respect to the electrode width L of the stripe electrode 8 and the width S of the space 10 at the time of halftone display is shown in FIG. Shown in As shown in FIG. 31, it was found that when L> S, the dark line at the boundary portion (a line that appears optically dark because the alignment direction is aligned with the polarization axis direction) is thicker and non-uniform. If the dark line is thick and non-uniform, problems such as reduced transmittance and occurrence of unevenness occur. This is a reverse relationship to the relationship between the electrode width L of the striped electrode 8 and the width S of the pace 10 proposed in the previous application. Note that this result is before the polymerization of the monomers in the liquid crystal, and this problem hardly occurs if a sufficiently high voltage is applied during polymerization, but when the polymerization voltage is low or a polymer is used. This may cause a problem when the alignment is performed only with the stripe electrode 8 and the space 10 without using the pretilt angle imparting technique, and the alignment at both the stripe electrode 8 and the space 10 and the boundary is more stable. Is better.
[0082]
The principle of this embodiment is shown in FIG. As shown in FIG. 32, the electrode width L and the space width S of the striped electrode 8 are made different between the vicinity of the boundary portion (spine) and the position away from the boundary portion. Specifically, the electrode width L of the striped electrode 8 is narrower than the space width S near the boundary, and the electrode width L of the striped electrode 8 is wider than the space width S near the boundary. In the vicinity of the boundary portion, the dark line is thin and uniform, and in the region away from the boundary portion, the change in transmittance due to the variation in the widths S and L can be reduced, thereby improving display unevenness.
[0083]
The liquid crystal display device according to the present embodiment will be specifically described below using examples.
[Example 4-1]
The present embodiment will be described with reference to FIG.
A 15-inch XGA panel (pixel pitch: 297 μm, number of pixels: 1024 × 768) was produced. FIG. 33 shows one pixel of this panel. On one substrate, the TFT 16, the gate bus line 4, the drain bus line 6, and the pixel electrode 3 including the striped electrode 8 and the space 10 were formed. A color filter layer and a common electrode were formed on the other substrate. As the substrate material, a glass substrate OA-2 (manufactured by Nippon Electric Glass Co., Ltd.) having a thickness of 0.7 mm was used. The striped electrode 8 was extended in four directions (upper right, lower right, upper left, lower left) from the center of the pixel.
[0084]
Here, the electrode width L of the stripe electrode 8 in the vicinity of the boundary portion (spine) is 2 μm, the width S of the space 10 is 4 μm, the electrode width L of the stripe electrode 8 in the region away from the boundary portion is 4 μm, and the space width. S was 2 μm. The distance x from the boundary end to the stripe electrode 8 pattern width changing portion was 5 μm.
[0085]
A vertical alignment film (polyimide material manufactured by JSR) was formed on these substrates using a printing method, and heat treatment was performed at 180 ° C. for 60 minutes. Furthermore, these substrates were bonded together via a spacer having a diameter of 4 μm (manufactured by Sekisui Fine Chemical Co., Ltd.) to produce an empty cell into which no liquid crystal was injected. A liquid crystal panel having a negative dielectric anisotropy (manufactured by Merck) with a small amount of a photopolymerizable monomer (Dainippon Ink Co., Ltd.) added thereto was poured into this cell to produce a liquid crystal panel. The addition amount of the photopolymerizable monomer was 2.4 wt%. Next, a voltage was applied to the liquid crystal panel and irradiated with ultraviolet rays, and the monomers were polymerized to form a polymer. The applied voltage during polymerization is 10 V, and the UV irradiation amount is 2000 mJ / cm.2(Λ = 365 nm).
[0086]
[Example 4-2]
The present embodiment will be described with reference to FIG. This example is the same as Example 4-1, except for the following requirements. The electrode width of the striped electrode 8 in the vicinity of the boundary portion and the region away from the boundary portion was continuously changed. This also provides the same effect as in Example 4-1.
[0087]
As described above, according to the present embodiment, improvement in display characteristics in a liquid crystal display device that defines a pretilt angle of liquid crystal molecules and a tilt direction when a voltage is applied using a polymer material that is polymerized by heat or light. Can be planned.
[0088]
[Fifth Embodiment]
Next, a liquid crystal display device substrate and a liquid crystal display device using the same according to a fifth embodiment of the present invention will be described.
Liquid crystal by pretilt angle applying technique using a polymer that regulates liquid crystal alignment by sealing a liquid crystal layer containing a monomer that is polymerized by light or heat, and polymerizing a polymerizable component while applying a voltage to the liquid crystal layer. In the display device, if the same image is continuously displayed for a long time, an image sticking phenomenon may occur in which the previous image remains even if the display is changed. An object of the present embodiment is to prevent a seizure phenomenon based on a pretilt angle imparting technique using a polymer.
[0089]
As a result of intensive studies, it has been found that the image sticking phenomenon can be prevented by setting the molecular weight of the monomer to be added to about the same as or less than 1.5 times the average molecular weight of the liquid crystal composition. In particular, it has been found that an excellent effect of preventing a seizure phenomenon can be obtained by setting the monomer molecular weight to be equal to or lower than the average molecular weight of the liquid crystal composition. Further, it has been found that the seizure phenomenon can be prevented by setting the molecular weight of the polymerization initiator to be equal to or lower than the average molecular weight of the liquid crystal composition. This will be specifically described below.
[0090]
As a result of studying various monomers, polymerization initiators, and liquid crystal compositions in order to solve the seizure of a liquid crystal display device using a polymer with a pretilt angle imparting technique, the following knowledge was obtained.
Molecular weight M of liquid crystal compositionlc, Monomer molecular weight Mm, Polymerization initiator molecular weight MiniWhen
(I) MmThe seizure rate decreases as the value decreases. In particular, MmIs MlcThe seizure rate is low when it is about the same as or below.
(Ii) MiniThe smaller the is, the lower the seizure rate. In particular, MiniIs MlcThe seizure rate is low when it is about the same as or below.
(Iii) The monomer concentration is preferably 0.1 wt% or more and 10 wt% or less from the viewpoint of image sticking rate. In particular, about 0.3 wt% is desirable.
(Iv) The polymerization initiator is necessary to reduce the optimum ultraviolet irradiation amount and increase the production efficiency. However, if the concentration is too high, the image sticking rate deteriorates. The polymerization initiator concentration is desirably 0.1 wt% or more and 10 wt% or less. In particular, about 2 wt% is desirable.
[0091]
The image sticking rate is obtained as follows. A black and white checker pattern is displayed on the LCD display area for a long time. Immediately after that, a predetermined halftone is displayed on the entire display area, the luminance difference between the portion displaying white and the portion displaying black is obtained, and the luminance difference is displayed as the portion displaying black. Divide by the brightness of to obtain the image sticking rate.
[0092]
The liquid crystal display device according to the present embodiment will be described below specifically using examples and comparative examples. In all of the following examples, a vertical alignment film is used, the liquid crystal has a negative dielectric anisotropy, and the polarizing plate is attached to both sides of the liquid crystal panel in a crossed Nicols state, so that the change axis of the polarizing plate is a bus. The direction is 45 ° to the line. The panel size is 15 inches and the resolution is XGA.
[0093]
[Example 5-1]
An LCD having a pretilt angle was produced using a polymer using a liquid crystal material in which 0.3 wt% of a diacrylate monomer having a molecular weight of about 350 was mixed with a liquid crystal composition having an average molecular weight of about 350. The burn-in rate after 48 hours of this LCD was 5%.
[0094]
[Comparative Example 5-1]
On the other hand, an LCD having a pretilt angle was produced using a polymer using a liquid crystal material in which 0.3 wt% of a diacrylate monomer having a molecular weight of about 700 was mixed with a liquid crystal composition having an average molecular weight of about 350. The image sticking rate of this LCD for 48 hours was 30%.
[0095]
[Example 5-2]
5 wt% of a polymerization initiator having a molecular weight of about 260 was added to a diacrylate monomer having a molecular weight of about 350. An LCD was prepared in which a pretilt angle was imparted using a polymer using a liquid crystal material in which 0.3 wt% of a monomer containing the polymerization initiator was mixed with a liquid crystal composition having an average molecular weight of about 350. The burn-in rate after 48 hours of this LCD was 5%. In this example, the amount of ultraviolet irradiation necessary for the expression of the predetermined tilt angle was 1/10 of that in Example 5-1.
[0096]
[Comparative Example 5-2]
On the other hand, 5 wt% of a polymerization initiator having a molecular weight of about 350 was added to a diacrylate monomer having a molecular weight of about 350. An LCD was prepared in which a pretilt angle was imparted using a polymer using a liquid crystal material in which 0.3 wt% of a monomer containing the polymerization initiator was mixed with a liquid crystal composition having an average molecular weight of about 350. The image sticking rate of this LCD for 48 hours was 10%.
[0097]
[Example 5-3]
An LCD having a pretilt angle was produced using a polymer using a liquid crystal material in which 0.3 wt% of a diacrylate monomer having a molecular weight of about 350 was mixed with a liquid crystal composition having an average molecular weight of about 350. This LCD was annealed at 120 ° C. for 2 hours, but the orientation was stable.
[0098]
[Sixth Embodiment]
Next, a liquid crystal display device according to a sixth embodiment of the present invention is described with reference to FIGS. A liquid crystal panel provided with a pretilt angle using a polymer is made of amorphous TN (Japanese Patent Application No. 6-148122), ferroelectric liquid crystal (SID'96, Digest, p699) or the like for the purpose of stabilizing the alignment state. It has been reported. The prior art will be described by taking amorphous TN as an example. A diacrylate resin is added to a liquid crystal containing a predetermined chiral material, and the liquid crystal is injected into an empty panel. By irradiating ultraviolet rays while applying voltage to the liquid crystal layer, both the effect of fixing the alignment defects (disclination) and controlling the number of defects by applying voltage are brought about. TN hysteresis and instability of defects can be eliminated. The point of the pretilt angle technology using polymer is to polymerize the photocurable resin in the liquid crystal layer by applying a voltage to the liquid crystal layer and irradiating ultraviolet rays with the liquid crystal molecules aligned in a predetermined direction. is there.
[0099]
The present embodiment is based on the above-described conventional technology, and presents an improvement when the technology is applied to an LCD having another display method or structure, and further, the reliability of a pretilt angle providing technology using a polymer is presented. Provide technology to further improve performance. In the following, multi-domain in IPS-LCD (transverse electric field switching type liquid crystal display device), improvement of display characteristics (contrast etc.) in reflection type and transflective type liquid crystal display devices, and pretilt angle application technology using polymer As a reliability improvement, reduction of the image sticking phenomenon (the alignment state of the liquid crystal slightly changes by energization and the display pattern remains) will be specifically described with reference to examples.
[0100]
[Example 6-1]
FIG. 35 shows an arrangement configuration of display electrodes and common electrodes of a conventional IPS-LCD. The IPS method requires a rubbing process as in the TN method in order to horizontally align the liquid crystal. As the alignment material, a horizontal alignment film (for example, manufactured by JALS-1054 / JSR) is used. By applying an initial alignment with a slight inclination with respect to the electric field, alignment deformation at the time of voltage application can be easily performed. In addition, the amount of deformation is made uniform. IPS has a wide viewing angle characteristic even in a mono-domain structure (one identical alignment region in a pixel), but multi-domaining is required for further wide viewing angle. For this reason, as shown in FIG. 35, a technology has been established in which the display electrode 70 and the common electrode 26 that are arranged opposite to each other on the same substrate surface are made into a chevron structure ("<")-shaped structure to form two domains. . With this structure, when a voltage is applied, the liquid crystal molecules 24a are divided into two domains as shown in FIG. However, this structure results in further lowering the transmittance because the display electrode 70 and the common electrode 26 are bent in the substrate plane.
[0101]
FIG. 36 shows the electrode structure of the IPS-LCD according to this example. The electrode structure according to the present embodiment is not a chevron structure as shown in FIG. 35, but is a linear display electrode 70 and a common electrode 26 which are almost the same as the conventional one, and the electrode ends thereof are broken ellipses in FIG. As shown in α1 and α2, a partially inclined electrode structure bent at a predetermined angle in the substrate surface is formed. The liquid crystal molecules 24a in the ellipse α1 and the ellipse α2 rotate symmetrically with the longitudinal center line of the common electrode 26 as the axis of symmetry when a voltage is applied, and this is propagated to the other liquid crystal molecules 24a in the same domain. Is realized. Furthermore, a stable two-domain panel can be produced by adding a pretilt angle imparting technique using a polymer to this structure. In the pretilt angle providing technique using a polymer, the monomer is polymerized after waiting for the liquid crystal alignment to reach a steady state. After polymerization, the liquid crystal alignment is stabilized including the transient response. Although the case where the dielectric anisotropy is positive has been described above, the present invention can be similarly applied to the case where the dielectric anisotropy is negative by changing the orientation process direction by approximately 90 °.
[0102]
[Example 6-2]
FIG. 37 shows a reflective LCD according to this example. The reflective LCD can realize display quality close to paper white without parallax by using the uneven reflective electrode 72. However, in the case of the concavo-convex reflective electrode 72, the alignment disorder of the liquid crystal having the concavo-convex as a nucleus is more likely to occur than the flat reflective electrode. In the case where the rubbing process is performed, alignment failure occurs due to insufficient alignment process at the bottom of the uneven surface. In this situation, when a polymer layer 36 is formed on the concavo-convex reflective electrode 72 as shown in FIG. 37 by applying a pretilt angle applying technique using a polymer, a desired uniform alignment is realized and the alignment is a polymer layer. 36, the occurrence of disclination or the like due to orientational disturbance often observed in the past can be greatly suppressed.
[0103]
In FIG. 37, the common electrode 26 is formed of a transparent pixel electrode material such as ITO. Alignment films 32 and 34 are formed on the uneven reflection electrode 72 and the common electrode 26, respectively. The liquid crystal layer 24 is sealed between the facing alignment films 32 and 34. A polymer layer 36 is formed on the alignment films 32 and 34. The polymer in the polymer layer 36 is tilted on the outermost surface in contact with the liquid crystal layer 24, and it is possible to impart a pretilt to the liquid crystal molecules 24a.
[0104]
[Example 6-3]
A transflective LCD according to this embodiment is shown in FIGS. The transflective LCD has a light transmission part and a light reflection part, and can realize a good display regardless of the brightness of the surrounding illumination. In a transflective LCD, the amount of retardation change in the light transmission part that changes due to the rotation (switching) of the liquid crystal molecules is λ / 2, and in the light reflection part, the light passes through the forward path and the return path. It is necessary to switch so that the quantity is λ / 4.
[0105]
In order to realize this, there is a technique (multi-gap structure) for partially changing the liquid crystal cell thickness, but this is not preferable because the manufacturing process becomes complicated. Therefore, it is conceivable to use a pretilt angle providing technique using a polymer. A pretilt angle imparting technique using a polymer is characterized in that a specific orientation state can be fixed as an initial orientation. By utilizing this, it is possible to change the amount of retardation change during switching between the light transmission part and the light reflection part, and it becomes possible to use panels having the same cell thickness.
[0106]
FIG. 38 shows a cross section of the horizontal alignment type LCD according to the present embodiment cut in the direction perpendicular to the substrate surface. FIG. 39 shows a state viewed in the normal direction of the substrate surface at a position corresponding to FIG. As shown in FIGS. 38 and 39, the array substrate side glass substrate 20 and the counter substrate side glass substrate 30 are arranged to face each other and the liquid crystal layer 24 is sealed. An uneven reflective electrode 72 is partially formed on the array substrate side glass substrate 20. The region where the uneven reflective electrode 72 is formed is the light reflecting portion 106, and the region where the uneven reflective electrode 72 is not formed is the light transmitting portion 108. A λ / 4 plate 76 is attached to the surface of the glass substrate 20 opposite to the surface on which the concave / convex reflective electrode 72 is formed, and a polarizing plate 73 is attached thereon. On the surface of the glass substrate 30 opposite to the liquid crystal layer 24 side, a polarizing plate 74 arranged in crossed Nicols with a polarizing plate 73 is attached. Although not shown, an alignment film is formed on the interface between the substrates 20 and 30 and the liquid crystal layer 24.
[0107]
Next, a procedure for providing a pretilt angle using a polymer in the transflective LCD according to this embodiment will be described. In the panel of the pixel electrode structure shown in FIGS. 38 and 39, the orientation of the liquid crystal molecules 24a in the light transmitting portion 108 and the light reflecting portion 106 is slightly inclined from the extending direction (vertical direction in FIG. 39) of the uneven reflecting electrode 72. Horizontal orientation. The liquid crystal molecules 24a have a positive dielectric anisotropy Δε. When a voltage is applied between the concavo-convex reflective electrodes 72, the liquid crystal molecules 24a in the interelectrode gap (light transmission portion 108) perform a switching operation that rotates approximately 90 ° in the horizontal direction (direction parallel to the substrate surface). At this time, the retardation generally changes from (−λ / 4) to λ / 4.
[0108]
In the state where no voltage is applied to the liquid crystal layer 24, ultraviolet rays are irradiated from the array substrate side glass substrate 20 side to stabilize the initial alignment state. When this treatment is performed, the monomer at the light transmitting portion 108 is mainly consumed for polymer formation at the substrate interface, and the monomer at the light reflecting portion 106 that is shielded from light by the concavo-convex reflective electrode 72 remains. Next, in the state where a voltage is applied to the liquid crystal layer 24, ultraviolet light is irradiated from the counter substrate side glass substrate 30 side. For the voltage to be applied, a condition for increasing the maximum switching efficiency of the light reflecting portion 106 is appropriately selected. In this case, since there are many unreacted monomers in the light reflecting portion 106, the polymerization at the interface is sufficiently generated, whereas the light transmitting portion 108 is short of monomers. Therefore, the liquid crystal alignment state of the light transmitting portion 108 is almost the same as that after the first-stage ultraviolet irradiation, and the retardation change amount finally switches to approximately λ / 2, that is, the λ / 4 plate is rotated by 90 °. . On the other hand, the liquid crystal molecules 24a of the light reflecting portion 106 have an azimuth angle in an initial alignment state with respect to the liquid crystal molecules 24a of the light transmitting portion 108 by applying an optimum voltage to give a pretilt angle using a polymer. It can be in the state rotated 45 degrees. By doing so, the liquid crystal molecules 24a of the light reflecting portion 106 can be switched so that the retardation change amount is approximately 45 ° rotation of the λ / 4 plate. As described above, by changing the optical switching capability (the amount of change in retardation during liquid crystal switching) of the light reflecting portion 106 and the light transmitting portion 108, it is efficient as a transflective display without providing a multi-gap structure in the pixel. Switching becomes possible.
[0109]
It can be easily guessed that the same effect can be obtained in the above-described embodiments when a liquid crystal having negative dielectric anisotropy and horizontal alignment are combined. In this case, the initial alignment treatment direction differs by 90 ° and is almost perpendicular to the electrode stretching direction. In addition, unlike the above-described embodiment using light shielding by the concave and convex reflection electrode 72, by using a light shielding body such as a photomask, the conditions for providing a pretilt angle using a polymer individually in each region are changed, and each region is changed. The switching ability of the liquid crystal can also be changed.
[0110]
[Example 6-4]
FIG. 40 shows a cross section of the horizontal alignment type transflective LCD according to the present embodiment cut in the direction perpendicular to the substrate surface. FIG. 41 shows a state viewed in the normal direction of the substrate surface at a position corresponding to FIG. As shown in FIGS. 40 and 41, the array substrate side glass substrate 20 and the counter substrate side glass substrate 30 are arranged to face each other, and the liquid crystal layer 24 having positive dielectric anisotropy is sealed. An uneven reflective electrode 72 is partially formed on the glass substrate 20 on the array substrate side, and a transparent electrode 104 is formed in a region where the uneven reflective electrode 72 is not formed. The region where the uneven reflective electrode 72 is formed becomes the light reflecting portion 106, and the region where the transmissive electrode 104 is formed becomes the light transmitting portion 108. A λ / 4 plate and a polarizing plate 73 are attached in this order on the surface of the glass substrate 20 opposite to the surface on which the concave / convex reflective electrode 72 is formed. A common electrode 26 is formed on the glass substrate 30 on the liquid crystal layer 24 side. Further, a polarizing plate 74 arranged in parallel Nicol with a polarizing plate 73 is attached to the surface of the glass substrate 30 opposite to the liquid crystal layer 24. Although not shown, an alignment film is formed on the interface between the substrates 20 and 30 and the liquid crystal layer 24.
[0111]
The procedure for giving a pretilt angle using a polymer is the same as in Example 6-3. In the light transmission portion 108, when a voltage is applied, the liquid crystal molecules 24a that are aligned horizontally on the substrate surface rise almost perpendicularly to the substrate surface. At this time, the retardation changes from λ / 2 to 0 (when a sufficient voltage is applied), and the transmission mode is efficiently switched. On the other hand, in the light reflecting portion 106, the initial pretilt angle of the liquid crystal molecules 24a is about 45 °, and the retardation of about λ / 4, which is half of the light transmitting portion 108, is seen from the front. . For this reason, the retardation can be changed from λ / 4 to 0, and the switching can be efficiently performed as the reflection mode.
[0112]
As described above, both regions of the light transmission part 108 and the light reflection part 106 can be efficiently switched. Here, the pretilt angle imparting technique using a polymer is used for partially and appropriately performing retardation correction in accordance with transmission and reflection in the light transmission unit 108 or the light reflection unit 106, respectively. If a pretilt angle is imparted using a polymer in a state where a voltage is applied, a change in retardation during switching can be reduced. Similarly to Example 6-3, it is also possible to partially change the pretilt angle application condition using a polymer by utilizing the presence or absence of voltage application, a photomask, or the like.
[0113]
[Example 6-5]
Next, an embodiment for preventing seizure due to pretilt in the case of using a pretilt angle providing technique using a polymer will be described. As a result of our investigation and investigation, the seizure phenomenon associated with the pretilt angle application technology using polymers is different from the electric seizure that is usually observed, and the pretilt angle caused by insufficient polymerization of the monomers. It has been found that there are also fluctuations. Therefore, stronger and more stable alignment control is required for a pretilt angle application technique using a polymer.
[0114]
First, an example in which a conventional technology for providing a pretilt angle using a polymer is applied to a vertical alignment panel, particularly an MVA-LCD will be described. As is well known, the MVA-LCD forms an insulating structure or a slit (a pixel electrode is partially patterned and removed) on a TFT substrate, and an insulating structure or A slit (a part of the common electrode partially removed by patterning) is formed. A vertical alignment film was applied and formed on both substrates. This is a polyamic acid type alignment film.
[0115]
A negative liquid crystal having a negative dielectric anisotropy Δε, for example, a Merck material (Δε: −3.8, NI point: 70 °) was injected into the empty panel where both substrates were bonded. Here, in the negative liquid crystal, a functional monomer, a photoinitiator and the like for imparting a pretilt angle using a polymer are mixed in a ratio of several percent or less. The concentration of the functional monomer is relative to the liquid crystal matrix, and the concentration of the photoinitiator is relative to the monomer. As this material, both a monomer having a liquid crystalline skeleton and a non-liquid crystalline monomer can be used. Basically, any material that mixes with nematic liquid crystal to form a nematic phase can be used. This time, Dainippon Ink Co., Ltd. liquid crystal monoacrylate monomer (ULC-001-K1) was used as a representative material. Under application of voltage 5V, UV (high pressure mercury lamp) 4J / cm2Irradiation produced a cell.
[0116]
A polarizing plate was attached to the obtained cell, and changes in the TV characteristics before and after a driving test in which an AC voltage of 5 V was applied for 24 hours were investigated. The TV characteristics were compared between the initial stage (before the driving test) and after the driving test, and the change in transmittance in a steep region of the TV curve was expressed as a percentage. On the other hand, a similar experiment was performed under the same conditions for the main structure and skeleton using a monomer having two or more functional groups as a material. These results are shown in Table 1.
[0117]
[Table 1]
[0118]
As shown in Table 1, it has been found that good results can be obtained by using a polyfunctional monomer. This is presumably because the polymer formed has a cross-linked structure due to polyfunctionalization. Table 2 shows similar examples when a cross-linking material is added.
[0119]
[Table 2]
[0120]
The acrylate monomer has been mainly described above, but it can also be applied to other monomers such as styrene-based, methacrylic acid-based, acrylonitrile-based conjugated monomers, and non-conjugated monomers such as ethylene-based, vinyl acetate-based, and vinyl chloride-based monomers. It is.
[0121]
In addition, the cross-linked structure is considered to play an important role when a so-called copolymer (copolymer) is formed by mixing different monomers. For example, it is considered that there is an effect of compensating for the defects of individual monomers in various characteristics such as solubility in mother liquid crystals, electrical characteristics, and stability such as image sticking. FIG. 42 shows a cross section of the LCD according to the present embodiment cut in the direction perpendicular to the substrate surface. As shown in FIG. 42, the liquid crystal layer 24 has a copolymerized polymer layer 37 having a crosslinked structure in the vicinity of the surfaces of both the substrates 20 and 30. FIG. 43 schematically shows an example of the structure of the copolymer. As shown in FIG. 43, the copolymer has, for example, a structure in which two types of repeating units (CRU) A and B are alternately arranged.
[0122]
Furthermore, in the above description, the functional monomer is described. However, it is naturally possible to give a pretilt angle using a polymer by a mixture of an oligomer and a monomer. In this case, examples of the oligomer include polyester acrylate, polyurethane acrylate, epoxy acrylate, polyether acrylate, oligo acrylate, alkyd acrylate, and polyol acrylate. If the degree of polymerization is 10 or less, the solubility is sufficient and more preferable.
[0123]
As described above, this embodiment can be summarized as follows. In the improvement of the IPS-LCD, a sufficient time voltage is applied to a liquid crystal panel having a structure in which the liquid crystal alignment tends to become unstable, thereby stabilizing and uniforming the liquid crystal alignment state. In addition, by applying a pretilt angle using a polymer, uniform stable orientation can be obtained.
[0124]
In the reflection type LCD, there is an effect of eliminating the adverse effect on the liquid crystal alignment due to the surface unevenness when the uneven reflection electrode 72 is formed.
[0125]
As a basic technique for imparting a pretilt angle using a polymer for improving reliability, the polymer has a cross-linked structure and is copolymerized in order to stably form the polymer at the substrate interface.
[0126]
As described above, according to the present embodiment, the liquid crystal alignment can be made uniform and stable with respect to a panel with unstable liquid crystal alignment. Further, according to the present embodiment, the reliability of the liquid crystal panel provided with a pretilt angle using a polymer, in particular, seizure can be significantly reduced.
[Seventh Embodiment]
[0127]
Next, a liquid crystal display device according to a seventh embodiment of the present invention is described with reference to FIGS. The present embodiment relates to a liquid crystal display device in which an operation component in the azimuth direction is given to switching of liquid crystal molecules using a striped electrode provided on a substrate surface.
[0128]
Conventionally, as an active matrix type liquid crystal display device, a TN mode liquid crystal display device in which a liquid crystal material having a positive dielectric anisotropy is aligned so as to be twisted by 90 ° between opposite substrates in parallel is widely used. It is used. However, the TN mode liquid crystal display device has a problem of poor viewing angle characteristics. For this reason, various studies have been made to improve the viewing angle characteristics.
[0129]
As a method for replacing the TN mode, an IPS (In Plane Switching) mode in which an electric field is applied in the substrate surface direction (lateral direction) to drive the device has been proposed. The mode that switches in the azimuth direction, represented by the IPS mode, is extremely superior in terms of viewing angle compared to the mode that switches in the polar direction represented by the TN mode.
[0130]
In such switching in the azimuth direction, it is important that the azimuth angle of the director in the dark state does not deviate from the initial alignment state by driving the liquid crystal molecules. However, even in the orientation control using the rubbing method, when the rubbing strength is low, the orientation direction shifts with respect to the azimuth angle over time as driving is performed, and the contrast is lowered. In the case of using non-contact alignment control such as ultraviolet irradiation that can obtain only anchoring strength (alignment regulating force) weaker than alignment control using the rubbing method, the problem of misalignment of the alignment direction is more serious.
[0131]
An object of the present embodiment is to provide a high-quality liquid crystal display device that suppresses a shift in liquid crystal alignment over time due to driving in a liquid crystal display device having an azimuth direction element for liquid crystal switching as described above. There is.
[0132]
In the liquid crystal switching, in the liquid crystal display device having an azimuth direction element in the switching direction, mainly in the IPS mode in which the azimuth direction component is dominant, in order to suppress the deterioration of the contrast with time, the voltage is increased by driving. It is necessary to prevent the orientation direction from changing from the initial state when off (when a voltage lower than the threshold voltage is applied). However, no specific method other than increasing the rubbing strength has been disclosed for the problem of suppressing this misalignment.
[0133]
As a result of diligent trials, realized by injecting liquid crystal containing photocurable composition and reacting and forming photocured material in a state that almost coincides with the alignment regulation direction in the azimuth angle direction of the alignment film (alignment control layer) It has been found possible. The principle of this embodiment is shown in FIGS. 44 (a) and 44 (b). FIG. 44A shows a state of deviation of liquid crystal alignment over time due to driving of a conventional liquid crystal display device, and FIG. 44B shows liquid crystal alignment over time due to driving of the liquid crystal display device according to the present embodiment. The state which prevented the shift | offset | difference of this is shown. As shown in FIG. 44B, in the liquid crystal display device according to the present embodiment, the photocurable composition contained in the liquid crystal in a state where the liquid crystal molecules 24 are aligned in the alignment regulating direction of the alignment film. Has been reacted and cured. The photocurable composition has a force to keep the liquid crystal molecules 24 in the alignment state at the time of curing. Therefore, as shown in FIG. 44 (b), in addition to the alignment restriction on the liquid crystal molecules 24 of the alignment film, the alignment restriction shown by the arrow 101 in the figure is added to the liquid crystal molecules 24 of the photocured product. The problem of misalignment with time due to driving is greatly improved.
[0134]
At this time, a voltage lower than the threshold voltage on the transmittance characteristic when viewed in the direction perpendicular to the substrate surface, or a voltage lower than the voltage at which there is almost no change in azimuth and only changes in the polar angle direction is applied. The photocurable composition may be cured. That is, the anchoring energy of the azimuth angle must be set to be equal to or greater than the value of the alignment film alone, and the alignment of the liquid crystal molecules at the interface must be more firmly fixed. As shown in FIG. 45 (a), when curing is performed in a state where a voltage higher than the threshold voltage is applied and switching is performed, the orientation regulating force by the photocured material is stored in the direction indicated by the arrow 102 in the figure. End up. For this reason, as shown in FIG. 45 (b), after driving for a long time, the alignment direction of the liquid crystal molecules in the dark state becomes unstable, and a pretilt is generated even when no voltage is applied. Therefore, the photocured material may be formed so that the alignment regulating force is added in the same direction (arrow 101), not in the direction different from the alignment regulating direction of the alignment film (arrow 102). And even if the polar angle orientation is slightly changed, the contrast has little problem. If it is a mode in which the orientation is slightly displaced in the polar angle direction at first, not only the orientation is stabilized if it is stabilized with a photo-cured product in a state where such a polar angle is slightly changed, Response speed is also greatly improved.
[0135]
The liquid crystal display device according to the present embodiment will be specifically described below using examples.
[Example 7-1]
This embodiment will be described with reference to FIG. FIG. 46A shows a part of a pixel of the liquid crystal display device according to the present embodiment, and FIG. 46B shows a cross section taken along the line FF of FIG. 46A. As shown in FIGS. 46A and 46B, an IPS mode evaluation cell in which comb-like electrodes 100 having a width of 5 μm and a gap width of 20 μm were formed on the array substrate-side glass substrate 20 was produced. The alignment film was formed by spin-coating a polyimide material on the substrate. In order to give five types of alignment regulating force to the alignment film, rubbing was performed with three different intensities, and two types of photo-alignment were obtained by irradiating linearly polarized ultraviolet rays with two different intensities. The azimuth angle direction of the alignment regulating force was set to 10 ° with respect to the longitudinal direction of the comb-like electrode 100.
[0136]
The result of measuring the azimuth anchoring energy of the above five types of alignment films using the Neel Wall method, the contrast of the initial black display of the evaluation cell, and the evaluation cell over a period of 72 hours in an environment of 35 ° C. Table 3 shows the contrast at the time of black display after the white display is continued with the AC voltage.
[0137]
[Table 3]
[0138]
As shown in Table 3, the smaller the azimuth anchoring energy, the greater the deviation of the orientation direction after continuing white display with an AC voltage for 72 hours in an environment of 35 ° C., resulting in a decrease in contrast. Observed. However, there was no significant change in the one with the highest azimuth anchoring energy.
[0139]
Next, 0.3 wt% of a bifunctional acrylate monomer manufactured by Merck was added to the above five types of evaluation cells, and cured by ultraviolet irradiation with no voltage applied after injection. The results of improvement are shown in Table 4. As shown in Table 4, in four types of cells having a small anchoring energy, a significant contrast improvement effect was observed by applying a pretilt angle using a polymer.
[0140]
[Table 4]
[0141]
[Example 7-2]
The present embodiment will be described with reference to FIG. FIG. 47A shows a part of a pixel of the liquid crystal display device according to this embodiment, and FIG. 47B shows a cross section taken along the line GG of FIG. 47 (a) and 47 (b), a comb-like electrode 100 having a width of 5 μm formed on the array substrate side glass substrate 20 and a comb having a width of 5 μm formed on the counter substrate side glass substrate 30 are used. An oblique electric field switching mode evaluation cell was fabricated in which the tooth-like electrodes 101 were alternately arranged with a gap width of 20 μm when viewed in the direction perpendicular to the substrate surface. The alignment film was formed by spin-coating a polyimide material on the substrate.
[0142]
In order to impart three types of alignment regulating force to the alignment film, rubbing was performed at three strengths in the same manner as in Example 7-1. Further, the azimuth angle direction of the alignment regulating force was made parallel to the longitudinal direction of the comb-like electrodes 100 and 101.
[0143]
Next, 0.3 wt% of a bifunctional acrylate monomer manufactured by Merck Co., Ltd. was added to the above three types of evaluation cells, and a DC voltage of 2.3 V, which is lower than the threshold voltage on the transmittance characteristics after injection, was applied. The response speed was compared between those cured by UV irradiation and those not added. The results are shown in Table 5. The response speed of the added material was increased. Note that no deterioration or the like was observed in contrast or the like.
[0144]
[Table 5]
[0145]
As described above, according to the present embodiment, in the liquid crystal display device having elements in the azimuth direction for switching of liquid crystal molecules, it is possible to suppress a shift in liquid crystal alignment over time due to driving. In addition, according to the present embodiment, the response speed can be improved at the same time by applying to a mode having a polar angle element for switching of liquid crystal molecules, such as a liquid crystal mode driven by an oblique electric field. A liquid crystal display device can be realized.
[0146]
The substrate for a liquid crystal display device according to the first embodiment of the present invention described above and the liquid crystal display device using the same are summarized as follows.
(Appendix 1)
A substrate that sandwiches the liquid crystal together with the opposing substrate disposed oppositely;
A bus line formed on the substrate;
A switching element connected to the bus line;
A stripe electrode and a space connected to the switching element and connected in parallel to the bus line are provided, and the electrode width of the stripe electrode in the vicinity of the bus line is narrower than the width of the inner electrode. Pixel electrode
A substrate for a liquid crystal display device, comprising:
[0147]
(Appendix 2)
In the substrate for a liquid crystal display device according to appendix 1,
The pixel electrode has a total area of 50% or less of a total area of the electrode region.
A substrate for a liquid crystal display device.
[0148]
(Appendix 3)
In the substrate for a liquid crystal display device according to appendix 1 or 2,
The pixel electrode includes the striped electrode and the space also in the vicinity of a boundary between a plurality of alignment division regions for dividing the liquid crystal.
A substrate for a liquid crystal display device.
[0149]
(Appendix 4)
In the liquid crystal display substrate according to any one of appendices 1 to 3,
The pixel electrode is formed such that the electrode length of the stripe electrode in the vicinity of the bus line is longer than the electrode length of the stripe electrode inside the pixel electrode.
A substrate for a liquid crystal display device.
[0150]
The substrate for a liquid crystal display device according to the second embodiment of the present invention described above and the liquid crystal display device using the same are summarized as follows.
(Appendix 5)
A substrate that sandwiches the liquid crystal together with the opposing substrate disposed oppositely;
A bus line formed on the substrate;
A switching element connected to the bus line;
A pixel electrode that is connected to the switching element and includes a striped electrode and a space arranged in parallel to the bus line between the switching element and the bus line;
A substrate for a liquid crystal display device, comprising:
[0151]
(Appendix 6)
In the substrate for a liquid crystal display device according to appendix 5,
The pixel electrode includes a plurality of stripe electrodes and spaces at a connection portion with the switching element, and at least one of the stripe electrodes is cut off at the connection portion, so that the switching element and the stripe current are cut. A gap is formed between the extreme parts
A substrate for a liquid crystal display device.
[0152]
(Appendix 7)
In the substrate for liquid crystal display device according to appendix 6,
The gap has a length of not less than 0.5 μm and not more than 5 μm.
A substrate for a liquid crystal display device.
[0153]
(Appendix 8)
The substrate for a liquid crystal display device according to any one of appendices 5 to 7,
The width of the stripe electrode has a length of 0.5 μm or more and 5 μm or less.
A substrate for a liquid crystal display device.
[0154]
(Appendix 9)
In the liquid crystal display device in which the array substrate and the counter substrate are bonded to face each other and the liquid crystal is sealed,
The liquid crystal display substrate according to any one of appendices 1 to 8 is used as the array substrate.
A liquid crystal display device.
[0155]
(Appendix 10)
In the liquid crystal display device according to appendix 9,
The liquid crystal includes a liquid crystal molecule that has a negative dielectric anisotropy and is vertically aligned when no voltage is applied, and a polymer that defines a pretilt angle of the liquid crystal molecule and / or a tilt direction during driving.
A liquid crystal display device.
[0156]
(Appendix 11)
In the liquid crystal display device according to appendix 9 or 10,
An alignment regulating structure is disposed at least on the counter substrate side.
A liquid crystal display device.
[0157]
The liquid crystal display device substrate and the liquid crystal display device using the same according to the third embodiment of the present invention described above can be summarized as follows.
[0158]
(Appendix 12)
In the liquid crystal display device in which the array substrate and the counter substrate are bonded to face each other and the liquid crystal in contact with the alignment film or the electrode is sealed,
In the liquid crystal, a polymer layer that defines a pretilt angle of liquid crystal molecules and / or a tilt direction during driving is formed on either the alignment film or the electrode.
A liquid crystal display device.
[0159]
(Appendix 13)
In the liquid crystal display device according to attachment 12,
The thickness of the polymer layer is not less than 10 mm and not more than 5000 mm
A liquid crystal display device.
[0160]
(Appendix 14)
In the liquid crystal display device according to appendix 12 or 13,
The orientation of the polymer on the outermost surface in contact with the liquid crystal in the polymer layer is different from the orientation direction defined by the orientation film or electrode.
A liquid crystal display device.
[0161]
(Appendix 15)
In the liquid crystal display device according to appendix 14,
The polymer has different alignment lamination states in a plurality of regions
A liquid crystal display device.
[0162]
(Appendix 16)
In the liquid crystal display device according to appendix 14 or 15,
The polymer has optical anisotropy
A liquid crystal display device.
[0163]
The liquid crystal display device substrate and the liquid crystal display device using the same according to the fourth embodiment of the present invention described above are summarized as follows.
(Appendix 17)
A substrate that sandwiches the liquid crystal together with the opposing substrate disposed oppositely;
A stripe electrode and a space periodically arranged in different directions for each predetermined region on the substrate, and the electrode width or the space of the stripe electrode near the boundary of the predetermined region and other than the vicinity of the boundary It is formed so that at least one of the space widths is different
A substrate for a liquid crystal display device, comprising:
[0164]
(Appendix 18)
In the liquid crystal display device substrate according to appendix 17,
In the vicinity of the predetermined region boundary,
The electrode width of the stripe electrode ≦ the width of the space
And
Other than the vicinity of the boundary,
The electrode width of the striped electrode ≧ the width of the space
Be
A substrate for a liquid crystal display device.
[0165]
(Appendix 19)
In the liquid crystal display substrate according to appendix 17 or 18,
The electrode width of the striped electrode is continuously changing.
A substrate for a liquid crystal display device.
[0166]
(Appendix 20)
The liquid crystal display substrate according to any one of appendices 17 to 19,
The stripe electrode and the space constitute a pixel electrode
A substrate for a liquid crystal display device.
[0167]
(Appendix 21)
In the liquid crystal display device in which the array substrate and the counter substrate are bonded to face each other and the liquid crystal is sealed,
The substrate for a liquid crystal display device according to any one of appendices 17 to 20 is used as the array substrate.
A liquid crystal display device.
[0168]
(Appendix 22)
In the liquid crystal display device according to attachment 21,
The liquid crystal includes a liquid crystal molecule that has a negative dielectric anisotropy and is vertically aligned when no voltage is applied, and a polymer that defines a pretilt angle of the liquid crystal molecule and / or a tilt direction during driving.
A liquid crystal display device.
[0169]
The liquid crystal material according to the fifth embodiment of the present invention described above and the liquid crystal display device using the liquid crystal material are summarized as follows.
(Appendix 23)
A liquid crystal material used in a liquid crystal display device,
Monomer molecular weight MmAnd the average molecular weight M of the liquid crystal composition excluding the monomerlcBetween
Mm<Mlc× 1.5
The relationship of
Liquid crystal material characterized by
[0170]
(Appendix 24)
In the liquid crystal material according to attachment 23,
further,
Mm≦ Mlc
Be
Liquid crystal material characterized by
[0171]
(Appendix 25)
In the liquid crystal material according to appendix 23 or 24,
The monomer concentration is 0.1 wt% or more and 10 wt% or less.
Liquid crystal material characterized by
[0172]
(Appendix 26)
In the liquid crystal material according to any one of appendices 23 to 25,
The monomer has a molecular weight MiniContaining a polymerization initiator
Mini≦ Mlc
Satisfying the relationship
Liquid crystal material characterized by
[0173]
(Appendix 27)
In the liquid crystal material according to appendix 26,
The concentration of the polymerization initiator in the monomer is 0.1 wt% or more and 10 wt% or less.
Liquid crystal material characterized by
[0174]
(Appendix 28)
28. The liquid crystal material according to any one of appendices 23 to 27,
The molecular weight of the monomer is 400 or less
Liquid crystal material characterized by
[0175]
(Appendix 29)
In a liquid crystal display device in which two substrates are bonded to each other and a liquid crystal layer is sealed between the substrates,
The liquid crystal layer includes the liquid crystal material according to any one of appendices 23 to 28.
A liquid crystal display device.
[0176]
The liquid crystal display device according to the sixth embodiment of the present invention described above can be summarized as follows.
(Appendix 30)
In the lateral electric field switching type liquid crystal display device in which the liquid crystal is oriented substantially horizontally on the substrate surface and a lateral electric field substantially parallel to the substrate surface is applied,
It has a polymer layer that gives a pretilt angle to liquid crystal molecules formed by polymerizing the polymerizable component while applying a voltage to the liquid crystal containing a polymerizable component that is polymerized by light or heat.
A lateral electric field switching type liquid crystal display device.
[0177]
(Appendix 31)
A liquid crystal containing a polymerizable component that is sealed by a pair of opposed substrates and polymerized by light or heat;
A reflective electrode disposed on one of the substrates;
A polymer layer formed on the reflective electrode by polymerizing the polymerizable component while applying a voltage to the liquid crystal, and providing a pretilt angle to the liquid crystal molecules;
A reflective liquid crystal display device comprising:
[0178]
(Appendix 32)
A liquid crystal containing a polymerizable component that is sealed by a pair of opposed substrates and polymerized by light or heat;
A light reflecting portion and a light transmitting portion disposed on one of the substrate surfaces;
A polymer layer that imparts a pretilt angle to liquid crystal molecules formed by polymerizing the polymerizable component while adjusting a voltage applied to the liquid crystal to form the light reflecting portion and the light transmitting portion;
A transflective liquid crystal display device comprising:
[0179]
(Appendix 33)
In the transflective liquid crystal display device according to attachment 32,
The liquid crystal molecules on the light reflecting portion are rotated by approximately 45 ° in a plane substantially parallel to the substrate surface to obtain a retardation change amount of λ / 4.
The liquid crystal molecules on the light transmission part are rotated by approximately 90 ° in a plane substantially parallel to the substrate surface, resulting in a retardation change amount of λ / 2.
A transflective liquid crystal display device.
[0180]
(Appendix 34)
In the transflective liquid crystal display device according to attachment 32,
The liquid crystal molecules on the light reflecting portion are rotated by approximately 45 ° in a plane substantially perpendicular to the substrate surface to obtain a retardation change amount of λ / 4.
The liquid crystal molecules on the light transmission part are rotated by approximately 90 ° in a plane substantially perpendicular to the substrate surface, resulting in a retardation change amount of λ / 2.
A transflective liquid crystal display device.
[0181]
(Appendix 35)
In the transflective liquid crystal display device according to appendix 33 or 34,
The polymer layer defines an initial alignment state of the liquid crystal molecules on the light reflecting portion and the light transmitting portion.
A transflective liquid crystal display device.
[0182]
(Appendix 36)
In a liquid crystal display device in which a polymer layer that gives a pretilt angle to liquid crystal molecules is formed on a substrate surface by polymerizing the photopolymerizable component while applying a voltage to a liquid crystal containing a photopolymerizable component that is polymerized by light.
The photopolymerizable component has two or more types of photopolymerizable monomers and is polymerized by copolymerization.
A liquid crystal display device.
[0183]
(Appendix 37)
In a liquid crystal display device in which a polymer layer that gives a pretilt angle to liquid crystal molecules is formed on a substrate surface by polymerizing the photopolymerizable component while applying a voltage to a liquid crystal containing a photopolymerizable component that is polymerized by light.
The photopolymerizable component is polymerized and cross-linked
A liquid crystal display device.
[0184]
The liquid crystal display device according to the seventh embodiment of the present invention described above can be summarized as follows.
(Appendix 38)
A pair of opposed substrates;
An alignment film formed on each of the opposing surfaces of the substrate;
A liquid crystal layer including a nematic liquid crystal and a photocured material cured so that an azimuth azimuth in an alignment direction of liquid crystal molecules substantially coincides with an azimuth azimuth in the alignment control of the alignment film;
An electrode structure for generating an electric field having a component parallel to the substrate surface for the liquid crystal layer;
A liquid crystal display device comprising:
[0185]
(Appendix 39)
In the liquid crystal display device according to attachment 38,
An azimuthal anchoring energy for liquid crystal molecules on the surface of the alignment film is
3 × 10-FiveJ / m2Must be
A liquid crystal display device.
[0186]
(Appendix 40)
In the liquid crystal display device according to appendix 38 or 39,
As the alignment regulating factor of the liquid crystal molecules, the uneven shape on the surface of the alignment film is used.
A liquid crystal display device.
[0187]
【The invention's effect】
As described above, according to the present invention, the light transmittance can be improved without reducing the response speed at the time of gradation change.
[Brief description of the drawings]
FIG. 1 is a diagram (part 1) for explaining the principle for determining the structure of a pixel electrode 3 according to a first embodiment of the present invention;
FIG. 2 is a diagram (part 2) for explaining the principle for determining the structure of the pixel electrode 3 according to the first embodiment of the present invention;
FIG. 3 is a diagram (No. 3) for explaining the principle for determining the structure of the pixel electrode 3 according to the first embodiment of the invention;
FIG. 4 is a diagram (No. 4) for explaining the principle for determining the structure of the pixel electrode 3 according to the first embodiment of the invention;
FIG. 5 is a diagram showing an array substrate when one pixel 2 of the MVA-LCD according to Example 1-1 of the first embodiment of the invention is viewed in the normal direction of the substrate surface;
6 is a diagram showing an LCD cross-sectional shape cut along line AA in FIG. 5;
FIG. 7 is a diagram showing a modification of the MVA-LCD according to Example 1-1 of the first embodiment of the invention.
FIG. 8 is a diagram showing an array substrate when one pixel 2 of the MVA-LCD according to Example 1-2 of the first embodiment of the invention is viewed in the normal direction of the substrate surface;
FIG. 9 is a diagram showing an array substrate when one pixel 2 of the MVA-LCD according to Example 1-3 of the first embodiment of the invention is viewed in the normal direction of the substrate surface;
FIG. 10 is a diagram showing an array substrate when one pixel 2 of the MVA-LCD according to Example 1-4 of the first embodiment of the present invention is viewed in the normal direction of the substrate surface.
11 is a diagram showing a cross-sectional shape of an LCD cut along a line BB in FIG.
12 is a diagram showing a cross-sectional shape of an LCD cut along a line CC in FIG.
FIG. 13 is a diagram showing a modification of the MVA-LCD according to Example 1-4 of the first embodiment of the invention.
FIG. 14 is a diagram showing an MVA-LCD having a two-divided alignment region. FIG. 14A shows a state where one pixel 2 of the MVA-LCD is viewed in the normal direction of the substrate surface. FIG. 14B shows a cross section obtained by cutting the MVA-LCD shown in FIG. 14A in parallel with the drain bus line 6.
FIG. 15 is a pixel microscope observation view of the MVA-LCD as viewed in the normal direction of the substrate surface.
FIG. 16 is a view of one pixel 2 of the proposed MVA-LCD as viewed in the normal direction of the substrate surface.
17 shows a cross-sectional shape cut along the line DD in FIG.
FIG. 18 is a pixel microscope observation view of a conventional MVA-LCD as viewed in the normal direction of the substrate surface.
FIG. 19 is a diagram showing one pixel 2 of an MVA-LCD having a two-part alignment region according to Example 2-1 of the second embodiment of the present invention.
FIG. 20 is a diagram showing one pixel 2 of an MVA-LCD having a two-part alignment region according to Example 2-2 of the second embodiment of the present invention.
FIG. 21 is a diagram showing a cross section of a liquid crystal display device according to a third embodiment of the present invention cut in a direction perpendicular to the substrate surface.
FIG. 22 is a diagram showing an array substrate side of a cross section obtained by cutting the liquid crystal display device according to the third embodiment of the present invention in a direction perpendicular to the substrate surface;
FIG. 23 is a diagram showing an array substrate side of a cross section obtained by cutting the liquid crystal display device according to the third embodiment of the present invention in a direction perpendicular to the substrate surface;
FIG. 24 is a diagram showing an array substrate side of a cross section obtained by cutting the liquid crystal display device according to the third embodiment of the present invention in a direction perpendicular to the substrate surface;
FIG. 25 is a diagram showing an array substrate side of a cross section obtained by cutting the liquid crystal display device according to the third embodiment of the present invention in a direction perpendicular to the substrate surface;
FIG. 26 is a diagram showing an array substrate side of a cross section obtained by cutting the liquid crystal display device according to the third embodiment of the present invention in a direction perpendicular to the substrate surface;
FIG. 27 is a diagram showing a proposed orientation control means.
FIG. 28 is a diagram showing the proposed orientation control means.
FIG. 29 is a diagram of a (fishbone-like) pattern in which stripe-shaped electrodes 8 facing a plurality of directions and spaces 10 are combined, viewed in the normal direction of the substrate surface.
30 is a view showing a cross section taken along line EE of FIG. 29. FIG.
FIG. 31 is a result of investigating the alignment state with respect to the electrode width L of the stripe electrode 8 and the width S of the space 10 at the time of halftone display, paying attention to the boundary part (spine part) between the stripe electrode 8 and the space 10; FIG.
FIG. 32 is a diagram showing the relationship between the electrode width L of the striped electrode 8 and the width S of the space 10 in the LCD according to the fourth embodiment of the present invention.
FIG. 33 is a diagram for explaining Example 4-1 according to the fourth embodiment of the present invention;
FIG. 34 is a diagram for explaining an example 4-2 according to the fourth embodiment of the present invention;
FIG. 35 is a diagram showing an arrangement configuration of display electrodes and common electrodes of a conventional IPS-LCD.
FIG. 36 is a diagram showing a configuration of a liquid crystal display device according to Example 6-1 of the sixth embodiment of the present invention;
FIG. 37 is a cross-sectional view showing a configuration of a liquid crystal display device according to Example 6-2 of the sixth embodiment of the present invention;
FIG. 38 is a cross-sectional view showing a configuration of a liquid crystal display device according to Example 6-3 of the sixth embodiment of the present invention;
FIG. 39 is a diagram showing a configuration of a liquid crystal display device according to Example 6-3 of the sixth embodiment of the present invention;
FIG. 40 is a cross-sectional view showing a configuration of a liquid crystal display device according to Example 6-4 of the sixth embodiment of the present invention;
FIG. 41 is a diagram showing a configuration of a liquid crystal display device according to Example 6-4 of the sixth embodiment of the present invention;
FIG. 42 is a cross-sectional view showing a configuration of a liquid crystal display device according to Example 6-5 of the sixth embodiment of the present invention;
FIG. 43 is a diagram schematically showing the structure of a copolymer.
FIG. 44 is a diagram for explaining the principle of a liquid crystal display device according to a seventh embodiment of the present invention;
FIG. 45 is a diagram for explaining the principle of a liquid crystal display device according to a seventh embodiment of the present invention;
FIG. 46 is a diagram showing a configuration of a liquid crystal display device according to Example 7-1 of the seventh embodiment of the present invention;
FIG. 47 is a diagram showing a configuration of a liquid crystal display device according to Example 7-2 of the seventh embodiment of the present invention;
[Explanation of symbols]
2 pixels
3 Pixel electrode
4 Gate bus line
6 Drain bus line
8, 8 ', 9 Striped electrode
10 spaces
11, 11a, 11b Gap
12 Inner electrode
16 TFT
20 Array substrate side glass substrate
22 Insulating film
23 Insulating film (gate insulating film)
24 Liquid crystal layer
24a, 24b Liquid crystal molecules
26 Common electrode
30 Opposite substrate side glass substrate
32, 34 Alignment film
36 Polymer layer
38 Curve showing change of orientation direction
60 Drain electrode
62 Source electrode
64 connection electrode
66, 68 Linear protrusion
70 Display electrode
72 Uneven reflection electrode
73, 74 Polarizing plate
76 λ / 4 plate
100 Comb electrode
101, 102 arrows
104 Transparent electrode
106 Light reflector
108 Light transmission part
X1 Dark part (or dark line)

Claims (8)

  1. A pair of opposed substrates;
    A liquid crystal including liquid crystal molecules sandwiched between the pair of substrates and having negative dielectric anisotropy and aligned in a plurality of directions when a voltage is applied ;
    Having stripe-shaped electrodes and spaces periodically arranged in different orientations for each predetermined region on one of the substrates;
    The liquid crystal display device is characterized in that at least one of the electrode width of the stripe-shaped electrode and the space width of the space is different between the vicinity of the predetermined region boundary portion and other than the vicinity of the boundary portion.
  2. The liquid crystal display device according to claim 1.
    In the vicinity of the predetermined region boundary,
    The electrode width of the stripe electrode ≦ the width of the space,
    Other than the vicinity of the boundary,
    An electrode width of the stripe-shaped electrode ≧ the width of the space.
  3. The liquid crystal display device according to claim 1 or 2,
    The liquid crystal
    Between the molecular weight M m of the monomer and the average molecular weight M lc of the liquid crystal composition excluding the monomer, M m <M lc × 1.5
    A liquid crystal display device comprising a liquid crystal material satisfying the above relationship.
  4. The liquid crystal display device according to claim 3.
    further,
    M m ≦ M lc
    A liquid crystal display device characterized by
  5. The liquid crystal display device according to any one of claims 1 to 4,
    The concentration of the monomer contained in the liquid crystal is 0.1 wt% or more and 10 wt% or less.
  6. The liquid crystal display device according to any one of claims 3 to 5,
    The monomer contains a polymerization initiator having a molecular weight Mini ,
    M ini ≦ M lc
    A liquid crystal display device characterized by satisfying the above relationship.
  7. The liquid crystal display device according to any one of claims 1 to 6,
    The liquid crystal is in contact with the alignment film or electrode,
    The liquid crystal display apparatus characterized by further having a partially formed on the alignment film, the polymer layer defining an inclination direction when the pretilt angle and / or the driving of the liquid crystal molecules.
  8. The liquid crystal display device according to claim 7.
    The liquid crystal display device, wherein the polymer has different alignment and lamination states in a plurality of regions.
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