JP2004163746A - Liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a VA (vertically aligned) type liquid crystal display having no projection of slit in effective pixels of the apparatus and having high luminance, little disclination around pixels and little display irregularity. <P>SOLUTION: In the liquid crystal display having a pixel electrode 4 on a first substrate 1, a color filter 9 formed on a second substrate 7, a common electrode 10 formed on the color filter 9, and perpendicular alignment films 11, 12 layered on the first substrate 1 and the second substrate 7, respectively, the perpendicular alignment film 11 on the first substrate 1 is rubbed to align liquid crystal molecules in a specified direction. A part of the second substrate 7 out of the effective pixel region and opposing to the end part of the pixel electrode 4 in the side of a specified direction is provided with a projection 15 to control the alignment of the liquid crystal molecules. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a liquid crystal display device having a wide viewing angle, and more particularly, to a VA (Vertically Aligned) type liquid crystal display device.
[0002]
[Prior art]
In general, liquid crystal display devices are characterized by being thin and light and having low power consumption. In particular, TFT (Thin Film Transistor) type liquid crystal display devices are widely used from portable terminals to large televisions. As this liquid crystal display device, a twisted nematic (TN) type liquid crystal display device has been often used, and high performance and quality are maintained as the display device.
[0003]
Therefore, in order to understand the VA liquid crystal display device of the present invention, the TN liquid crystal display device will be described first. As shown in FIG. 6A, in a TN mode TFT liquid crystal display device 50, a substrate 52 on which a pixel electrode 51 is formed and a substrate 54 on which a common electrode 53 is formed are arranged so as to face each other. A liquid crystal layer is formed by sealing liquid crystal between a pair of substrates. The alignment films 56 and 57 on both substrates 52 and 54 are subjected to an alignment process by rubbing or the like, and the alignment direction is set so as to differ from the alignment direction of the opposing substrates by 90 degrees (crossed Nicols arrangement). The liquid crystal molecules 55 are regulated in this alignment direction and are horizontally arranged in that direction, and are twisted and arranged 90 degrees in the horizontal direction between the substrates.
[0004]
Polarizing plates 58 and 59 are arranged on the outside of each substrate so as to face the substrate. In a normally black mode, the polarizing plates 58 and 59 are arranged so that the transmission axes of both polarizing plates are in the same direction. Sometimes, the polarizers are arranged such that the transmission axes of the polarizers form 90 degrees. The transmitted light that has passed through one of the polarizing plates becomes linearly polarized light and passes through the liquid crystal layer. At this time, since the liquid crystal molecules are arranged by being twisted by 90 degrees, the transmitted light is turned and the polarization direction is twisted by 90 degrees. At this time, in the normally black mode, the transmitted light that has passed through one liquid crystal layer cannot pass through the other polarizing plate, so that a dark display is obtained. In the normally white mode, the transmitted light that has passed through the liquid crystal layer is not reflected by the other polarizing plate. Can be passed, so the display is bright. The latter is a normally white mode TN mode liquid crystal display device that is often used.
[0005]
Next, when a voltage is applied between the electrodes 52 and 54 to apply an electric field to the liquid crystal molecules 55, the liquid crystal molecules 55 rise in the vertical direction and twist as shown in FIG. 6B. However, since the alignment regulating force is stronger on the alignment film surface, the alignment direction of the liquid crystal molecules 55 remains along the alignment film. In such a state, since the liquid crystal molecules are isotropic with respect to the light passing therethrough, the rotation of the polarization direction of the linearly polarized light incident on the liquid crystal layer does not occur. Therefore, in a normally white mode TN mode liquid crystal display device, linearly polarized light that has passed through the upper polarizing plate 59 cannot pass through the lower polarizing plate 52 and is in a dark state. Thereafter, when the voltage is not applied again, the state shown in FIG. 6A is obtained by the alignment regulating force, and the display returns to the bright state.
[0006]
The manufacturing technology of the TN type TFT type liquid crystal display device has made remarkable progress in recent years, and the contrast and color reproducibility at the front have surpassed those of the CRT. However, the TN mode liquid crystal display device has a great drawback that the viewing angle dependence is large and the viewing angle is narrow. Therefore, an in-plane switching (IPS) type liquid crystal display device that applies an electric field to a liquid crystal layer in a lateral direction has been proposed as a liquid crystal display device capable of achieving a wide viewing angle.
[0007]
As shown in FIG. 7, the IPS type liquid crystal display device 60 has a comb-shaped pixel electrode 61 and a comb-shaped shape on one of the substrates 62 and 64 sandwiching the liquid crystal layer. Of common electrodes 63 are arranged. The alignment films 66 and 67 on both substrates are subjected to alignment processing in the same direction as the direction of the comb-shaped electrodes 61 and 63, and when no voltage is applied to the electrodes, as shown in FIG. The liquid crystal molecules 65 are horizontally arranged in the same direction as the alignment direction. Polarizing plates 68 and 69 are arranged outside the substrates so as to face the substrates 62 and 64. The transmission axes of the two polarizing plates are 90 degrees, and the orientation directions of the substrates facing the transmission axes of the polarizing plates are the same. Direction or orthogonal direction.
[0008]
In the IPS mode liquid crystal display device, light transmitted through one of the polarizing plates passes through the liquid crystal layer in a linear direction. At this time, the liquid crystal layer is different from the liquid crystal layer of the TN mode liquid crystal display device (see FIG. 6). In contrast, since the light is not twisted, the transmitted light passes through the liquid crystal layer without turning. Therefore, the transmitted light is blocked by the other polarizers, resulting in a dark display. When a voltage is applied between the electrodes 61 and 63, a horizontal electric field is generated in the liquid crystal layer, and since the dielectric anisotropy of the liquid crystal molecules 65 is positive, some of the liquid crystal molecules in the liquid crystal layer are twisted in the electric field direction. It is. At this time, the linearly polarized transmitted light that has passed through one of the polarizing plates is birefringent when passing through the liquid crystal layer to become elliptically polarized transmitted light, and passes through the other polarizing plate to provide a bright display.
[0009]
The IPS type liquid crystal display device has a very good viewing angle characteristic because the birefringence does not change much depending on the direction of the liquid crystal molecules because the liquid crystal molecules are arranged in the horizontal direction without rising. Although a liquid crystal display device having an ultra-wide viewing angle can be obtained, it has the disadvantages that the response speed is very slow, the luminance is low, and the quality of chromaticity is low.
[0010]
Accordingly, a VA (vertically aligned) type liquid crystal display device has been developed as a type that provides a quick response while maintaining a wide viewing angle. In a liquid crystal display device 70 of this type, as shown in FIG. 8, a liquid crystal having a negative dielectric anisotropy is sealed between a pair of substrates 72 and 74, and one substrate 72 has a pixel electrode 71 and the other has a pixel electrode 71. A common electrode 73 is arranged on the substrate 74. The alignment films 76 and 77 on both substrates 72 and 74 are both subjected to vertical alignment processing. When no voltage is applied to the electrodes 71 and 73, the liquid crystal molecules 75 are vertically aligned as shown in FIG. Are arranged. Polarizing plates 78 and 79 are arranged in crossed Nicols outside the two substrates 72 and 74. When no voltage is applied to both the electrodes 71 and 73, the liquid crystal molecules 75 between the substrates are arranged vertically, so that the linearly transmitted light passing through one of the polarizing plates passes through the liquid crystal layer as it is. Blocked by the other polarizing plate, a dark body, that is, a black display is obtained. When a voltage is applied to both electrodes 71 and 73, the liquid crystal molecules 75 between the substrates are arranged horizontally, so that the transmitted light of linearly polarized light passing through one polarizing plate is birefringent when passing through the liquid crystal layer. The light passes through the elliptically polarized light, passes through the other polarizing plate, and becomes a light body, that is, a white display.
[0011]
In this VA-mode liquid crystal display device, when no voltage is applied to the electrodes, all the liquid crystal molecules 75 are aligned vertically and completely standing on the alignment film. Since the direction in which the liquid crystal molecules 75 fall in the horizontal direction cannot be controlled, the liquid crystal molecules 75 fall in random directions and are arranged horizontally, and display unevenness is conspicuous. There was a problem that ligation occurred.
[0012]
In order to regulate the direction in which liquid crystal molecules that stand vertically when a voltage is applied between the electrodes fall down and to achieve a uniform display state, when the voltage is not applied between the electrodes, the liquid crystal molecules are completely vertical. Instead, it is necessary to stand at a slight angle from the vertical axis, that is, at a tilt of the pretilt angle, and to make the distribution state of the tilt direction substantially the same for each pixel.
[0013]
On the other hand, as a technique for solving the above-mentioned problems of the VA type liquid crystal display device, a structure (domain) for controlling the alignment of a plurality of liquid crystal molecules in one pixel is formed. A liquid crystal display device of a so-called multi-domain-VA system (MVA system) as disclosed in US Pat.
[0014]
Before describing the invention disclosed in Patent Document 1, the operation principle of an MVA type liquid crystal display device shown as a conventional example in Patent Document 1 will be described with reference to FIG. FIG. 9A is a cross-sectional view of a conventional MVA liquid crystal display device in a state where no voltage is applied. The first projection patterns 106 are formed on the opposite surface of the glass substrate 101, and the second projection patterns 118 are alternately arranged on the opposite surface of the opposite substrate 136. A vertical alignment film 128 is formed on the opposing surfaces of the glass substrate 101 on which the TFT is formed and the opposing substrate 136 so as to cover the projection patterns 116 and 118, and liquid crystal molecules 130 are interposed between the glass substrate 101 and the opposing substrate 136. Containing liquid crystal material 129 is filled. The liquid crystal molecules 130 have negative dielectric anisotropy. Polarizing plates 131 and 132 are arranged in crossed Nicols outside the glass substrate 101 and the counter substrate 136, respectively.
[0015]
In this MVA liquid crystal display device, when no voltage is applied, the liquid crystal molecules 130 are aligned perpendicular to the substrate surface, so that the liquid crystal molecules 130a on the slopes of the first and second projection patterns 116 and 118 are placed on the slopes. Attempts to orient vertically. For this reason, the liquid crystal molecules 130 a on the slopes of the first and second projection patterns 116 and 118 are aligned obliquely with respect to the substrate surface, but the liquid crystal molecules 130 are vertically aligned in a wide area within the pixel. A good black display state is obtained.
[0016]
On the other hand, FIG. 9B is a cross-sectional view in a state in which a voltage at which the liquid crystal molecules 30 are inclined is applied, that is, in a halftone display state. As shown in FIG. 9A, the liquid crystal molecules 130a that are tilted in advance tilt more greatly in the tilt direction, and the surrounding liquid crystal molecules 130 also tilt in the same direction under the influence of the tilt of the liquid crystal molecules 130a. For this reason, the liquid crystal molecules 130 between the first projection pattern 116 and the second projection pattern 118 are arranged such that the major axis thereof rises to the right in the figure, and the liquid crystal molecules 130 are arranged on the left side of the first projection pattern 116. The liquid crystal molecules 130 and the liquid crystal molecules 130 on the right side of the second protrusion pattern 118 are arranged such that their long axes are lower right in the drawing.
[0017]
In the conventional MVA type liquid crystal display device, a plurality of domains having different inclination directions of liquid crystal molecules are defined in one pixel, and the first and second projection patterns 116 and 118 define a domain boundary. Therefore, the direction in which the vertically standing liquid crystal molecules fall can be regulated, so that uniform display is possible. However, in this MVA type liquid crystal display device, white display is performed by the birefringence effect of the liquid crystal material. Therefore, red (R) and green (G) in the white display body are caused by the wavelength dispersion effect at the time of birefringence. , Blue (B) have a difference in the transmittance of each pixel, and there is a drawback that coloring occurs. For this reason, the invention according to Patent Document 1 below employs not only the above-described projection pattern but also a pixel electrode having a slit as described below. The configuration of the MVA liquid crystal display device of the present invention will be described with reference to FIGS. FIG. 10 is a plan view of one pixel portion including R, G, and B as viewed from above, and FIG. 11 is a cross-sectional view taken along line AA of FIG.
[0018]
10 and 11, a plurality of gate bus lines 205 extend in the row direction (horizontal direction) on the surface of the glass substrate 201, and the gate bus lines 205 are covered with a gate insulating film 240. I have. A plurality of drain bus lines 207 extending in the column direction (longitudinal direction) of the figure are arranged on the gate insulating film 240, and the thin film transistors are disposed at the intersections of the gate bus lines 205 and the data bus lines 207. (TFT) 210 is provided. The drain electrode of the TFT 210 is connected to the corresponding drain bus line 207, and the gate bus line 205 also serves as the gate electrode of the corresponding TFT 210.
[0019]
The drain bus line 207 and the TFT 210 are covered with a protective insulating film 248, and the pixel electrode 212 is arranged in a region surrounded by the two gate bus lines 205 and the two data bus lines 207. Each pixel electrode 212 is connected to the source electrode of the corresponding TFT 210. The pixel electrode 212R of the red pixel, the pixel electrode 212G of the green pixel, and the pixel electrode 212B of the blue pixel are arranged in this order in the row direction to constitute one pixel.
[0020]
A counter substrate 236 is arranged at a certain interval on a glass substrate 201 on which a TFT is formed, and a projection pattern 218 is formed on a counter surface of the counter substrate 236 along a zigzag pattern extending in a column direction. ing. The projection patterns 218 are arranged at equal intervals in the row direction, and are bent at about 90 degrees at positions intersecting the gate bus lines 205 and at the center of the two gate bus lines 205.
[0021]
A slit 217 is formed in each pixel electrode 212, and the slits 217 are arranged along a virtual zigzag pattern obtained by shifting the projection patterns 218 in the row direction by half the arrangement pitch. As a result, an electric field is generated near the substrate in a direction oblique to the substrate surface. Since the oblique electric field tilts the liquid crystal molecules in a specific direction, the slit 127 defines a domain boundary similarly to the first projection pattern 16 shown in FIG. 9B.
[0022]
On the TFT substrate 235, a gate insulating film 240 and a protective insulating film 248 are provided on the glass substrate 201, and the pixel electrode 212 is formed on the protective insulating film 248. A slit 217 is formed in the pixel electrode 212, and the surfaces of the pixel electrode 212 and the protective insulating film 248 are covered with an alignment film 228.
[0023]
In the counter substrate 236, a color filter 251 is formed on a surface facing the glass substrate 227, and a common electrode 254 made of ITO is formed on the surface of the color filter 251. A projection pattern 218 is formed on the surface of the common electrode 254. The projection pattern 218 is formed of, for example, a polyimide-based photoresist. An alignment film 228 covers the surfaces of the projection pattern 218 and the common electrode 254.
[0024]
In this example, the width of the slit 217 formed in the pixel electrode 212B of the B pixel is set to 10 μm, the width of the slit 217 formed in the pixel electrodes 212R and 212G of the R and G pixels is set to 7 μm, The slit width is set so as to maximize the transmittance of the pixel.
[0025]
When the cell gap is 4 to 4.5 μm, the transmittance of the B pixel becomes relatively low. Therefore, in this example, the slit widths of the R and G pixels are shifted from the optimum values. As described above, the transmittance of the R and G pixels is relatively reduced as compared with the transmittance of the B pixel, thereby compensating for the decrease in the transmittance of the B pixel due to the wavelength dispersion of the birefringence effect. As a result, the difference in transmittance between the RGB pixels is reduced, and coloring during white display can be reduced.
[0026]
[Patent Document 1]
JP 2000-267079 A
[0027]
[Problems to be solved by the invention]
As described above, in the conventional VA-mode liquid crystal display device, if the pretilt direction of each liquid crystal molecule is not controlled in one direction, display unevenness is conspicuous and disclination occurs around a pixel. Existed. Further, the MVA liquid crystal display device disclosed in Patent Document 1 has a constitutional requirement that a slit is provided in a pixel electrode. However, since an electric field is not generated inside the slit, liquid crystal molecules in the slit are formed. There is a problem that the alignment regulation is weakened, and the liquid crystal molecules are inclined in opposite directions near the edges facing each other in the slit, so that the alignment of the liquid crystal molecules is easily disturbed in the slit, and display unevenness is easily generated. In addition to providing slits on the pixel electrodes, it is necessary to provide projections on each pixel to control the alignment of liquid crystal molecules for each pixel. As long as the projections are transparent, the loss in transmittance is almost zero. Although high luminance can be expected by eliminating it, as a practical problem, the loss of transmittance of this projection cannot be ignored, and as the luminance decreases, Look black phenomenon occurs.
[0028]
The present inventors comprehensively consider the advantages and disadvantages of the above-described VA or MVA liquid crystal display device, and have high brightness without any protrusions or slits in effective pixels of the liquid crystal display device. As a result of repeated experiments in order to obtain a VA type liquid crystal display device with less disclination around the pixels and less display unevenness, the present invention was completed.
[0029]
[Means for Solving the Problems]
In the VA type liquid crystal display device as shown in FIG. 8, the inventors of the present application have made the alignment directions of the respective alignment films on the substrates 72 and 74 to be opposite by 180 degrees and from the vertical axis to the pretilt angle. By aligning by a corresponding angle, it is possible to control the pretilt direction of each liquid crystal molecule in one direction, but in such a method, the pixel electrode is formed around one end of each pixel in the pretilt direction. The orientation of the liquid crystal molecules is disturbed by the presence of the corner 73, and disclination occurs in the peripheral portion. However, this disclination causes the protrusion for controlling the orientation of the liquid crystal molecules to be out of the effective pixel range. It has been found that it can be prevented by providing.
[0030]
That is, according to the present invention, the pixel electrode formed on the first substrate, the color filter formed on the second substrate, the common electrode formed on the color filter, the first substrate and the second substrate A liquid crystal display device having a vertical alignment film laminated thereon, wherein the first substrate and the second substrate are disposed to face each other, and a liquid crystal having a negative dielectric anisotropy is sealed between the pair of substrates; The vertical alignment film on the first substrate is subjected to a rubbing treatment so that liquid crystal molecules are aligned in a predetermined direction, and the second substrate portion facing the end of the pixel electrode on the predetermined direction side. A liquid crystal display device provided with a projection for controlling the alignment of liquid crystal molecules outside the effective pixel range is provided. According to such a liquid crystal display device, a VA type liquid crystal display device having high luminance because there are no protrusions or slits in the effective pixels and having little disclination around the pixels can be obtained.
[0031]
In this aspect, it is preferable that the vertical alignment film on the second substrate be rubbed so as to be oriented in a direction opposite to the predetermined direction by 180 degrees. According to this aspect, since the orientation of the liquid crystal molecules becomes better, disclination around the pixel can be further reduced.
[0032]
Further, it is preferable that an end of the pixel electrode on a predetermined direction side is an end opposite to an end on which a thin film transistor (TFT) is formed. According to this aspect, since the distance between the end of the pixel electrode and the projection is reduced, disclination of liquid crystal molecules generated at the end of the pixel electrode can be effectively reduced.
[0033]
Further, it is preferable that the protrusion is provided at a position of a black matrix provided on the second substrate. According to this aspect, since the black matrix is originally provided for the purpose of shielding light, even if the projections are provided, there is no influence on the luminance, so that a high-luminance liquid crystal display device can be obtained.
[0034]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 is a plan view showing the relationship between a pixel electrode and a color filter, FIG. 2 is a cross-sectional view taken along the line AA in FIG. 1, and FIGS. 3 (A) to 3 (D) show alignment of liquid crystal molecules on each pixel electrode. FIG. 4 is a cross-sectional view taken along line BB of the liquid crystal display device in the state of FIG. 3C, and FIG. 5 is a CC line of the liquid crystal display device in the state of FIG. 3D. FIG.
[0035]
On a first substrate 1 such as a glass substrate, scanning lines 2 and signal lines 3 are arranged in a matrix. A region surrounded by the scanning line 2 and the signal line 3 corresponds to one pixel, a pixel electrode 4 is arranged in this region, and a thin film transistor 5 (TFT) is formed at an intersection of the scanning line 2 and the signal line 3. I have. The TFT 5 is formed by stacking a source electrode 5b and a drain electrode 5c extending from the signal line 3 on a gate electrode 5a extending from the scanning line 2. An insulating film 6 is laminated on the source electrode 5b and the drain electrode 5c, and the drain electrode 5c and the pixel electrode 4 are connected via a contact hole formed in the insulating film 6. As shown in FIG. 1, the pixel electrode 4 has a substantially rectangular shape in which a portion of the TFT 5 is chipped when viewed from the normal direction of the first substrate 1, and is disposed on the first substrate 1 including the pixel electrode 4. Is covered with a vertical alignment film 11.
[0036]
On the other hand, a second substrate 7 is arranged at a predetermined distance from the first substrate 1, and a lattice-shaped black matrix 8 is formed on the second substrate 7. The black matrix 8 is provided on the first substrate 1 at a position corresponding to the scanning lines 2 and the signal lines 3. A color filter 9 is provided for each pixel on the second substrate, and is arranged in the row direction in the order of R, G, and B. The broken line in FIG. 1 indicates the peripheral edge 9a of the color filter 9, and the peripheral edge 9a of the color filter 9 overlaps with the black matrix 8 and corresponds to the vicinity of the contour of the pixel electrode 4. The black matrix 8 and the color filter 9 are covered with a common electrode 10 and a vertical alignment film 12 formed of ITO or the like, and when a voltage is applied to the pixel electrode 4, an electric field is generated between the pixel electrode 4 and the common electrode 10. Has been made to occur.
[0037]
Here, an example in which the color filter 9 and the black matrix 8 are provided so as not to overlap with each other is shown. However, since color filters of the same color are generally formed in a strip shape along the pixels of the vertical line, the color filter 9 is provided on the black matrix. A filter may be formed. In any of the above cases, when the liquid crystal panel is viewed from the display surface, a portion where the black matrix, which is the shield of the second substrate, and the shield (the TFT element, the wiring, etc.) of the first substrate do not contribute to the display. Therefore, this portion becomes an effective pixel range.
[0038]
In the following, the shape of the pixel electrode 4 is represented by a rectangle with the TFT part omitted for the sake of explanation. First, unless a rubbing process is performed on the vertical alignment film 11 provided on the surface of each pixel electrode 4, when no voltage is applied to each pixel electrode 4, each liquid crystal molecule is vertically aligned. When a voltage is applied to each pixel electrode, the orientation direction of the liquid crystal molecules becomes as shown by an arrow in FIG. When a rubbing process is performed on the alignment film 11 provided on the surface of the pixel electrode 4 so that alignment is performed in a direction indicated by a white arrow in FIG. 3B, a voltage is not applied to each pixel electrode 4. Although the liquid crystal molecules are tilted very slightly in the direction of the arrow but are arranged substantially in the vertical direction, when a voltage is applied to each pixel electrode 4, the liquid crystal molecules firstly become liquid crystal molecules at the interface of the alignment film. Are tilted, and the adjacent liquid crystal molecules are sequentially tilted, so that the liquid crystal molecules are aligned in one direction as shown in FIG. However, in the region near the upper end 13 in FIG. 3C, that is, in the region indicated by reference numeral 13 near the right end in FIG. 4, the alignment direction of the liquid crystal molecules 14 is aligned with the alignment direction of the other portions due to the edge effect of the pixel electrode 4. And disclination occurs. Note that if a rubbing process is performed on the vertical alignment film 12 on the second substrate side facing the pixel electrode 4 so as to be oriented in a direction 180 degrees opposite to the direction shown in FIG. Although the liquid crystal molecules 14 can be more strongly aligned, disclination still occurs in the region indicated by the reference numeral 13.
[0039]
On the other hand, as shown in FIGS. 3D and 5, when the projection 15 is provided outside the effective pixel range on the second substrate side facing the end of the pixel electrode 4, the projection 15 The alignment of the liquid crystal molecules 14 at the upper end, that is, at the right end in FIG. 5 is regulated, so that disclination in the end region 13 as shown in FIGS. 3C and 4 can be prevented. In this case, since a black matrix for shielding light is provided outside the effective pixel range on the second substrate side to partition each pixel, as shown in FIG. It is good to provide.
[0040]
In the case of the configuration shown in FIG. 5, the left side of the projection 15 effectively acts to regulate the alignment of liquid crystal molecules, but the right side does not effectively act. Therefore, the direction in which the liquid crystal molecules are regulated by the right side of the projection 15 is opposite to the direction in which the liquid crystal molecules are regulated by the vicinity of the edge of another pixel electrode (not shown) adjacent to the right side of the projection. If the distance between the pixel electrode and the edge of another pixel electrode adjacent to the right side is too short, display unevenness occurs. Therefore, by providing the projections 15 on the black matrix 8, the distance between the projections 15 and another pixel electrode adjacent to the right side of the projections 15 can be increased, and the right side of the projections 15 can be blackened. By shading with a matrix, a portion where display unevenness occurs can be set outside the effective pixel range, thereby achieving a good display image quality. In addition, as is likely to occur in a conventional MVA liquid crystal display device. Since there is no new light absorption due to irregular projections or the like, the luminance can be increased.
[0041]
In addition, on the left side of the projection 15, it may be better to overlap the left side of the projection with the edge of the pixel electrode 4 in order to remove the edge effect on the left side of the pixel electrode. In this case, a part of the protrusion 15 protrudes from the black matrix 8 and enters the effective pixel range, causing a slight decrease in luminance. However, since the edge effect of the pixel electrode 4 can be reduced more effectively. , It is possible to achieve better display image quality.
[0042]
【The invention's effect】
As described above, in the liquid crystal display device of the present invention, since the protrusion for regulating the alignment of the liquid crystal molecules is provided at the position where the black matrix exists on the counter substrate, disclination in the peripheral portion is reduced, and This has an excellent effect that a liquid crystal display device having a high luminance can be obtained as compared with a liquid crystal display device having a projection in an effective pixel.
[Brief description of the drawings]
FIG. 1 is a plan view showing a relationship between a pixel electrode and a color filter in a liquid crystal display device of the present invention.
FIG. 2 is a cross-sectional view taken along line AA of FIG.
FIG. 3 is a view for explaining the alignment direction of liquid crystal molecules on each pixel electrode, and FIG. 3A shows the alignment direction of liquid crystal molecules due to the edge effect when no alignment processing is performed. FIG. 3 (B) is a diagram for explaining an alignment direction given by rubbing, FIG. 3 (C) is a diagram for explaining generation of disclination when liquid crystal molecules are aligned in a predetermined direction, and FIG. () Is a diagram for explaining a configuration according to the present invention in which a projection is provided outside the effective pixel range.
FIG. 4 is a cross-sectional view taken along line BB of FIG. 3 (C).
FIG. 5 is a cross-sectional view taken along line CC of FIG. 3 (D).
FIG. 6 is a diagram illustrating the operation principle of a TN mode liquid crystal display device.
FIG. 7 is a diagram illustrating the operation principle of an IPS-mode liquid crystal display device.
FIG. 8 is a diagram illustrating an operation principle of a VA-mode liquid crystal display device.
FIG. 9 is a diagram illustrating the operation principle of an MVA liquid crystal display device.
FIG. 10 is a plan view of a conventional MVA liquid crystal display device having a slit and a projection.
FIG. 11 is a transverse sectional view taken along line AA of FIG. 10;
[Explanation of symbols]
1 First substrate
3 signal lines
4 Pixel electrode
5 TFT
7 Second substrate
8 Black Matrix
9 Color filters
10 Common electrode
11, 12 alignment film
14 Liquid crystal molecules
15 protrusion

Claims (4)

A pixel electrode formed on the first substrate, a color filter formed on the second substrate, a common electrode formed on the color filter, and a vertical alignment film laminated on the first substrate and the second substrate A liquid crystal display device having the first substrate and the second substrate opposed to each other and having a liquid crystal having a negative dielectric anisotropy sealed between the pair of substrates. The film is subjected to a rubbing treatment so that the liquid crystal molecules are oriented in a predetermined direction, and the liquid crystal molecules are out of an effective pixel range of the second substrate portion facing the end of the pixel electrode on the predetermined direction side. A liquid crystal display device provided with a projection for controlling the alignment of the liquid crystal. 2. The liquid crystal display device according to claim 1, wherein a rubbing process is performed so that the vertical alignment film on the second substrate is oriented in a direction opposite to the predetermined direction by 180 degrees. 3. 2. The liquid crystal display device according to claim 1, wherein an end of the pixel electrode on a predetermined direction is an end opposite to an end on which a thin film transistor (TFT) is formed. The liquid crystal display device according to claim 1, wherein the protrusion is provided at a position of a black matrix provided on the second substrate.

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