JP4080245B2 - Liquid crystal display - Google Patents

Liquid crystal display Download PDF

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Publication number
JP4080245B2
JP4080245B2 JP2002160063A JP2002160063A JP4080245B2 JP 4080245 B2 JP4080245 B2 JP 4080245B2 JP 2002160063 A JP2002160063 A JP 2002160063A JP 2002160063 A JP2002160063 A JP 2002160063A JP 4080245 B2 JP4080245 B2 JP 4080245B2
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liquid crystal
direction
electrode
crystal molecules
degrees
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JP2003186017A (en
Inventor
秀雄 千田
秀史 吉田
善郎 小池
有広 武田
泰俊 田坂
貴 笹林
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シャープ株式会社
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    • GPHYSICS
    • G02OPTICS
    • G02FDEVICES OR ARRANGEMENTS, THE OPTICAL OPERATION OF WHICH IS MODIFIED BY CHANGING THE OPTICAL PROPERTIES OF THE MEDIUM OF THE DEVICES OR ARRANGEMENTS FOR THE CONTROL OF THE INTENSITY, COLOUR, PHASE, POLARISATION OR DIRECTION OF LIGHT, e.g. SWITCHING, GATING, MODULATING OR DEMODULATING; TECHNIQUES OR PROCEDURES FOR THE OPERATION THEREOF; FREQUENCY-CHANGING; NON-LINEAR OPTICS; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics
    • G02F1/01Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333Constructional arrangements; Manufacturing methods
    • G02F1/1337Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers
    • G02F1/133707Structures for producing distorted electric fields, e.g. bumps, protrusions, recesses, slits in pixel electrodes

Abstract

<P>PROBLEM TO BE SOLVED: To perform suitable display in either case that a screen is viewed in the upward direction or down ward direction. <P>SOLUTION: A liquid crystal display device has a pair of substrates and a liquid crystal layer which is interposed between a pair of the substrates and wherein liquid crystal molecules are aligned nearly vertically to the substrate when no voltage between the substrates is applied and the liquid crystal molecules fall down in a plurality of directions so as to be nearly parallel to the substrate when voltage between the substrate is applied. If an angle is defined counterclockwise when the right direction of the screen is 0&deg;, when voltage is applied, the ratio of an area where the liquid crystal molecules are inclined in a direction of 0 to 180&deg; and the ratio of an area where the liquid crystal molecules are inclined in a direction of 180 to 360&deg; in the liquid crystal layer are different from each other. <P>COPYRIGHT: (C)2003,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal display device.
[0002]
[Prior art]
In recent years, liquid crystal display devices have been widely used for various applications by taking advantage of thin and light weight, low voltage driving, and low power consumption. As for display characteristics, characteristics comparable to those of CRTs have been realized, and it has come to be used for applications such as monitors and televisions where CRTs have been mainstream.
[0003]
Liquid crystal display devices have been increased in size, gradation display, and high contrast, and have been used as monitors for personal computers or television image display devices. In such an application, the liquid crystal display device needs to be visible from all directions.
[0004]
As a technique for realizing this wide viewing angle, an MVA (Multi-domain Vertical Alignment) type liquid crystal display device has been proposed by Fujitsu Limited.
[0005]
2A and 2B show a basic conceptual configuration of an MVA liquid crystal display device. 2A shows a liquid crystal display device when no voltage is applied to the substrates 201 and 202, and FIG. 2B shows a liquid crystal display device when a voltage is applied to the substrates 201 and 202. A bank 203 is provided on the substrate 201, and a bank 204 is provided on the substrate 202. In FIG. 2A, the liquid crystal molecules 212 are vertically aligned, and the liquid crystal molecules 211 near the banks 203 and 204 are aligned with an inclination. In FIG. 2B, the liquid crystal molecules 221 are aligned in accordance with the direction of the electric field. That is, it is oriented vertically when no voltage is applied, and when a voltage is applied, it is divided into four regions, each inclined in four directions. As a result of the mixing of the viewing angle characteristics of each region, a wide viewing angle can be obtained.
[0006]
Fujitsu Ltd. has applied for a patent for a technique for further improving the viewing angle characteristics of this MVA type liquid crystal display device (for example, Japanese Patent Laid-Open No. 10-153782) and a technique for improving display luminance (patent application number 2001-106283).
[0007]
[Problems to be solved by the invention]
Liquid crystal display devices are desired to realize a wider viewing angle. In addition, a high-brightness liquid crystal display device is desired. Furthermore, a liquid crystal display device having both a high viewing angle and high brightness is desired.
An object of the present invention is to provide a liquid crystal display device that realizes a wide viewing angle and / or high luminance.
[0008]
[Means for Solving the Problems]
According to one aspect of the present invention, a pair of substrates is sandwiched between a pair of substrates, liquid crystal molecules are vertically aligned with respect to the substrate when no voltage is applied between the substrates, and the substrate is subjected to voltage application between the substrates. A liquid crystal display device having a liquid crystal layer in which liquid crystal molecules are tilted in a plurality of directions so as to be substantially parallel is provided. When applying a voltage, the liquid crystal layer defines an angle counterclockwise when the right direction of the screen is 0 degree, The orientation direction of the liquid crystal molecules is regulated by the pixel electrode, and the liquid crystal molecules are tilted in four directions of 45 degrees, 135 degrees, 225 degrees, and 315 degrees, The ratio of the region where the liquid crystal molecules are tilted in the 45 ° and 135 ° orientations is different from the ratio of the region where the liquid crystal molecules are tilted in the 225 ° and 315 ° orientations.
By changing the ratio of the area where the liquid crystal molecules are inclined in the 45 degree and 135 degree azimuths and the ratio of the area where the liquid crystal molecules are inclined in the 225 degree and 315 degree directions to an appropriate ratio, the screen is oriented upward or downward. Appropriate display is possible even when viewed from above.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
FIG. 3 shows the visual characteristics of black and white contrast of an MVA type liquid crystal display (LCD). In the angle display on the circumference of FIG. 3, 0 ° indicates the right, 90 ° indicates the top, 180 ° indicates the left, and 270 ° indicates the bottom. The horizontal axis and the vertical axis indicate the tilt angle from the display surface, and the center is 0 °. A monochrome viewing angle of 10 (CR = 10) or more is realized even at an inclination angle of 80 degrees in the vertical and horizontal viewing angles.
[0016]
However, when a halftone is displayed, it is a normal display when viewed from the front, but when viewed from the lower viewing angle, a phenomenon is observed in which the whole is white and the contrast is lowered. We have found that this whitish phenomenon is peculiar to MVA, vertically oriented panels, or orientation-divided panels.
[0017]
This will be described with reference to FIGS. FIG. 4A is a view of the display surface observed from the front. A case where the liquid crystal display device 400 is divided into four domains 401 to 404 will be described. In the state where no voltage is applied or the liquid crystal is oriented substantially vertically and there is no light leakage, black light leakage is very small even at an oblique viewing angle. In the domains 401, 402, 403, and 404, the liquid crystal molecules A1, A2, B1, and B2 are inclined in different directions, respectively. In the low voltage region, the liquid crystal molecules A1, A2, B1, and B2 are almost vertical and have a small birefringence.
[0018]
FIG. 4B is a view of the display surface observed from the front (lower viewing angle). At an oblique viewing angle, the liquid crystal molecules lie down substantially. Since there is some angle with the polarizing plate, birefringence appears and light leaks.
[0019]
In FIG. 4C, the horizontal axis represents the applied voltage, and the vertical axis represents the amount of transmitted light. A characteristic line 411 shows the characteristic when observed from the front as shown in FIG. A characteristic line 412A shows the characteristics of the liquid crystal molecules B1 and B2 when observed from the front as shown in FIG. A characteristic line 412B shows the characteristics of the liquid crystal molecules A1 and A2 when observed from the front as shown in FIG.
[0020]
When the voltage slightly exceeds the threshold voltage and a dark gradation is displayed, the amount of transmitted light increases as shown in FIG. 4 (C). As shown in FIG. This is because the projection axis of the tilted liquid crystal molecule axis deviates from the projection axis of the polarizing plate axis. The same applies to the liquid crystal molecules located in the upper half of the pixel and the liquid crystal molecules located in the lower half of the pixel. Here, consider a case where an optical material is inserted in order to correct this light leakage. In this case, it is possible to compensate for a dark halftone, but an extra optical effect appears when black display is performed. For this reason, black floating occurs at an oblique viewing angle, and the viewing angle range with good contrast is narrowed.
[0021]
Basically, the above problem is solved by breaking the ratio of the region inclined in the upward (including upper right and upper left) direction and the region inclined in the downward (including lower right and lower left) direction.
[0022]
FIG. 5A shows transmitted light amount-applied voltage (T-V) characteristics when the ratio of the regions of the liquid crystal molecules A1, A2 and the liquid crystal molecules B1, B2 is the same. In this case, the shape of the characteristic line collapses, and the display surface becomes white.
[0023]
FIG. 5B shows TV characteristics when the ratio of the liquid crystal molecules A1 and A2 to the liquid crystal molecules B1 and B2 is adjusted to an appropriate value. The applied voltage and the amount of transmitted light are substantially proportional, and appropriate display can be performed.
[0024]
FIGS. 6A and 6B show a configuration in the case where the alignment is regulated by a fine slit. In FIG. 6A, all the liquid crystal molecules are configured to be tilted to the lower position of the screen. One pixel region 103 is divided into two alignment regions 101 and 102. A pixel region 103 is provided corresponding to the gate line 114 and the data line 113. The pixel region 103 is composed of an ITO (indium tin oxide) transparent electrode 111. The transparent electrode 111 is provided with a contact region 112 for connection to the drain of a thin film transistor (TFT). The ratio of the alignment regions 101 and 102 is 1: 1. In FIG. 6B, the ratio of the region 121 inclined upward and the region 122 inclined downward is set to 1: 1. The orientation of the regions 121 and 122 can be controlled by the direction of the slit of the transparent electrode 123.
[0025]
In FIG. 1A, the shape of the transparent electrode 133 is changed, and the ratio of the region 131 inclined upward and the region 132 inclined downward is set to 1: 3. As described above, the orientation in which the liquid crystal molecules are tilted is normally set to 1: 1, but the balance is intentionally lost to 1: X (X << 1).
[0026]
When the balance is lost in this way, the ratio of superposing the TV characteristics at the upper viewing angle and the lower viewing angle shown in FIG. 4C changes. At this time, the sum is in accordance with the ratio of the two TV characteristic lines 412A and 412B shown in FIG. Here, when the area indicated by the characteristic line 412A in FIG. 4C is increased, a blackish image becomes white as a whole, but since black and white contrast is obtained, a good display is obtained thanks to this contrast. . On the other hand, when the area indicated by the characteristic line 412B is increased, the black image may be crushed in black and partially inverted. However, blackish images do not become white but remain black. If the effect of the characteristic line 412A and the effect of the characteristic line 412B are completely mixed by 1: 1, both good characteristics are canceled out, and it is difficult to realize a good viewing angle characteristic. It was. However, it has been found that good display can be obtained by adjusting the ratio, particularly by setting the ratio of the region of the characteristic line 412A to 70 ± 20% of the whole.
[0027]
6A and 6B will be described in more detail. FIG. 6A shows an example in which all orientations are directed downward. The transparent electrode formed on the TFT substrate was patterned. Here, the transparent electrode 111 was provided in the shape of a comb. Here, the pixel is divided into two regions 101 and 102, and the upper teeth are set so that the comb teeth extend to the lower right. On the other hand, in the lower half, the comb teeth were set to extend to the lower left. Here, the width of each electrode of the comb teeth was set to 3 μm, and the gap between the comb teeth was set to 3 μm. FIG. 6B shows a case where the aperture ratio is set to the maximum and the vertical ratio is the same.
[0028]
FIG. 1A shows an example in which the vertical ratio is changed while the aperture ratio is set to the maximum. The vertical ratio was changed without changing the basic configuration of FIG. From this ITO electrode pattern, a comb-like ITO electrode was set in the upper region 131 in the upper right direction and in the lower region 132 in the lower left direction. Here, the ratio of the upper region 131 was set to 30% of the whole.
[0029]
FIG. 1B shows an example in which one ITO electrode pattern is provided vertically at the center of the left and right of the pixel, and the vertical ratio is changed. The pixel area 103 is divided into four areas 141 to 144. From this ITO electrode pattern, comb-like ITO electrodes were set in the upper direction in the upper regions 141 and 142 and in the lower direction in the lower regions 143 and 144. The method of extending the comb-like ITO electrode was set so that the arm was extended upward on the upper side of the pixel. On the other hand, on the lower side of the pixel, the arms were set to be lowered while spreading left and right. Here, the ratio of the upper areas 141 and 142 was set to 30% of the whole.
[0030]
FIG. 8A shows a main structure of the liquid crystal display device. The TFT 801 has a gate connected to the gate line 114, a source connected to the data line 113, and a drain connected to the transparent electrode 111. One end of the liquid crystal layer 802 is connected to the transparent electrode 111 on the TFT substrate, and the other end is connected to the common electrode (ground electrode) of the counter substrate. The auxiliary capacitor 803 has one end connected to the transparent electrode 111 through the contact region 701 and the other end connected to the ground potential.
[0031]
FIG. 8B is a cross-sectional view of the auxiliary capacitor 803 and its periphery. The auxiliary capacitor 803 is formed by providing an insulating layer between the metal layers 811 and 812. The metal layer 811 is not connected to the source electrode of the TFT 801 (FIG. 8A), but is formed in the same layer. Hereinafter, the metal layer 812 is also referred to as a storage capacitor (Cs) layer. The Cs layer 812 is connected to the ground potential. Metal layer 811 is connected to contact region 701 through contact hole 813.
[0032]
With reference to FIG. 7 and FIG. 9, a more accurate layout of the sawtooth electrode will be described. FIG. 7 corresponds to FIG. 6A, and FIG. 9 corresponds to FIG.
[0033]
In FIG. 7, electrodes 812 (FIG. 8B) for forming auxiliary capacitance (Cs) are formed on the left and right in the center of the pixel, and the ITO electrode 111 and the metal layer 811 (FIG. 8B). A contact region 701 for making contact with is formed. As shown in the enlarged view at the bottom of FIG. 7, the end of the sawtooth electrode 702 is separated from the contact region 701.
[0034]
FIG. 10 is a cross-sectional view of a TFT. A source electrode 1002 and a drain electrode 1003 are formed over the gate electrode 1001 with an insulating film 1011 interposed therebetween. Furthermore, an ITO electrode 1005 is formed thereon via an insulating film 1012. The ITO electrode 1005 and the drain electrode 1003 are connected through a contact hole 1004.
[0035]
The lower part of FIG. 9 shows an enlarged view of the contact region 901 of the TFT drain electrode and ITO electrode. It is important that the end of the stool-like electrode 903 is open, and it was designed to form a slit-like portion between the drain electrode and the drain electrode as much as possible. The slat-like electrode 902 is connected to the contact region 901.
[0036]
FIG. 11 is a cross-sectional view of a normal liquid crystal display device. A liquid crystal layer 1102 is provided between the counter substrate 1101 and the TFT substrate 1103. The counter substrate 1101 is formed by sequentially stacking a glass substrate 1111, a color filter 1112, and an ITO electrode 1113. In the TFT substrate 1103, a glass substrate 1124, an insulating layer 1123, an insulating layer 1122, and an ITO electrode 1121 are sequentially stacked. A source electrode 1133 and a drain electrode 1132 are formed over the gate electrode 1131 with an insulating layer 1123 interposed therebetween. The ITO electrode 1121 is connected to the drain electrode 1132.
[0037]
12A and 12B illustrate a liquid crystal display device in which a color filter 1223 is provided on a TFT substrate 1203. FIG. FIG. 12A is a plan view of a liquid crystal display device. FIG. 12B is a cross-sectional view taken along the line II-II in FIG. A liquid crystal layer 1202 is provided between the counter substrate 1201 and the TFT substrate 1203. The counter substrate 1201 is formed by stacking a glass substrate 1211 and an ITO electrode 1212. In the TFT substrate 1203, a glass substrate 1226, an insulating layer 1225, an insulating layer 1224, a color filter 1223, an acrylic resin layer 1222, and an ITO electrode 1221 are sequentially stacked. A source electrode 1233 and a drain electrode 1232 are formed over the gate electrode 1231 with an insulating layer 1225 interposed therebetween. The ITO electrode 1221 is connected to the drain electrode 1232.
[0038]
When the color filter 1223 is on the TFT substrate 1203, the electrode pattern can be freely laid out. In the configuration of FIG. 11, the luminance is lowered due to the influence of the lateral electric field from the data line, and the liquid crystal molecules are tilted in an orientation different from the desired angle, resulting in a problem of poor viewing angle characteristics. On the other hand, as shown in FIG. 12B, when the color filter 1223 is on the TFT substrate 1203, the data line is hidden below the color filter 1223. Here, as the slit electrode, an oblique electric field generated between adjacent pixels causes alignment failure. Therefore, conversely, the neighboring pixels are also used for improving the orientation. As shown in FIG. 13A, the gap 1321 between the electrode of the adjacent pixel and the own pixel is made the same as the gap 1322 of the slit in the pixel, and the display operation is performed with the adjacent pixels on the left and right. The phases of were adjusted. Specifically, frame inversion or line inversion driving was performed. At this time, for example, when gray display is performed on the entire surface, the distribution of the electric field in the own pixel and the distribution of the electric field between the pixels are exactly the same. And no orientation failure occurs at all. In this case, the orientation was uniform in the vertical direction on the entire surface, and good viewing angle characteristics and uniform and bright display could be realized.
[0039]
FIG. 13A shows ITO electrodes 1311 to 1316 corresponding to a region of 6 pixels. A contact region 1301 for connecting to the drain electrode of the TFT is provided on the upper left of each ITO electrode 1311 to 1316. The interval 1321 is an interval between the ITO electrodes 1311 to 1316. The interval 1322 is an interval between squirrel-shaped electrodes in each of the ITO electrodes 1311 to 1316. The intervals 1321 and 1322 are the same.
[0040]
In FIG. 13C, a contact hole 1331 for obtaining a connection with the TFT is provided at a connecting portion of the pixel at the center of the pixel to improve the aperture ratio and the stability of the orientation.
[0041]
FIG. 13B is a cross-sectional view taken along the line II of FIGS. 13A and 13C. On the TFT substrate 1342, a data line 1341 is provided below each ITO electrode 1314 to 1316.
[0042]
According to this embodiment, as shown in FIG. 12B, a pair of substrates 1201 and 1203 are provided. The liquid crystal layer 1202 is sandwiched between a pair of substrates 1201 and 1203. When no voltage is applied between the substrates 1201 and 1203, liquid crystal molecules are vertically aligned with respect to the substrates 1201 and 1203, and a voltage is applied between the substrates 1201 and 1203. As a result, the liquid crystal molecules are tilted in a plurality of directions so as to be substantially parallel to the substrates 1201 and 1203 (see FIGS. 1A and 1B). As shown in FIG. 1A, the liquid crystal layer 1203 is a region in which liquid crystal molecules are tilted in a 0 to 180 degree azimuth by defining an angle counterclockwise when a voltage is applied and the right azimuth of the screen is 0 degree. The ratio of 131 is different from the ratio of the region 132 in which the liquid crystal molecules are inclined in the direction of 180 to 360 degrees.
[0043]
In addition, the liquid crystal layer 1203 defines an angle in a counterclockwise direction when the right side orientation of the screen is 0 degree when a voltage is applied, and liquid crystal molecules are oriented in 45 degree and 135 degree orientations as shown in FIG. The ratio of the regions 141 and 142 in which the liquid crystal molecules are inclined is different from the ratio of the regions 143 and 144 in which the liquid crystal molecules are inclined in the directions of 225 degrees and 315 degrees. In the liquid crystal layer 1203, the ratio of the regions 141 and 142 in which the liquid crystal molecules are inclined in the 45 ° and 135 ° orientations is preferably 40% or less of the whole.
[0044]
As shown in FIG. 1B, the pixel electrode is a sawtooth pixel electrode having a width of 10 μm or less and a gap of 10 μm or less, and is provided on the TFT substrate 1203 (FIG. 12B). In the liquid crystal layer 1202, the orientation direction of the liquid crystal molecules is regulated by the pixel electrode, and the liquid crystal molecules are inclined in four directions. The pixel electrode has a shape of 45, 135, 225, and 315 degrees in the extending direction of the soot, and the liquid crystal layer 1202 has 45 directions of 45, 135, 225, and 315 degrees in which the liquid crystal molecules are inclined.
[0045]
The thin film transistor includes a gate, a source, and a drain. As shown in FIG. 9, the pixel electrode has a contact region 901 for connecting to the drain of the thin film transistor, and a slit is provided between at least a part 903 of the plurality of soot and the contact region 901. The gate line is connected to the gate of the thin film transistor. In the pixel electrode, a saw 902 that is closest to the gate line among the plurality of socks is connected to the contact region 901.
[0046]
As shown in FIG. 13A, the pixel electrode has the same gap 1321 between the gap 1322 of the self-shaped pixel electrode and the adjacent pixel electrode. As shown in FIG. 12A, the thin film transistor is connected to the pixel electrode 1221 in the TFT substrate 1203. The color filter layer 1223 is formed on the TFT substrate 1203.
[0047]
As described above, a display having a good viewing angle characteristic can be realized by this embodiment.
[0048]
(Second Embodiment)
The problems of the MVA liquid crystal display device will be described with reference to FIGS. FIG. 14 shows an MVA type liquid crystal display device. A slit 1405 is provided in the ITO pixel electrode 1404 on the TFT substrate side, and a bank 1401 is formed on the ITO electrode of the counter substrate using a resist. Furthermore, a gate line 1402, a data line 1403, and an auxiliary capacitance forming electrode 1406 are formed on the TFT substrate. The pixel electrode is divided into four regions 1411 to 1414. The liquid crystal molecules in each of the regions 1411 to 1414 are aligned in the directions of the liquid crystal molecules A1, B2, A2, and B1 in FIG. Here, compared with the structure of the TN type display, it is necessary to form a resist pattern on the ITO electrode of the counter substrate, which increases the number of processes and increases the cost.
[0049]
FIG. 15 shows a case where a slit 1504 is provided in the ITO electrode of the counter substrate. On the TFT substrate, a gate line 1501, a data line 1502, an auxiliary capacitance forming electrode 1505, and an ITO pixel electrode 1503 are formed. A black arrow 1521 indicates the direction of alignment regulation by the slit electrode 1504. A white arrow 1522 indicates the direction of alignment regulation by the gate line 1501 and the data line 1502. In the region 1511, since there are two or more directions for regulating the orientation, the response is slow.
[0050]
Furthermore, in this case, compared with a TN type display, the number of steps is increased due to the necessity of providing the slit 1504 in the ITO electrode of the counter substrate, resulting in an increase in cost. Further, in the case where the counter substrate is provided with a color filter, the color filter layer is exposed at the slit 1504, and there is a problem that reliability is lowered due to the drop of impurities from the color filter layer. Further, since the alignment regulation azimuth by the data line 1502 or the gate line 1501 and the alignment regulation azimuth by the slit electrode 1504 are different by 45 degrees, there is a problem that it takes time to stabilize the alignment and the response is slow.
[0051]
FIG. 16 illustrates a pattern of pixel electrodes according to an embodiment of the present invention. On the TFT substrate, a gate line 1601, a data line 1602, and fine slit pixel electrodes 1621 and 1622 are formed.
[0052]
A black arrow 1612 indicates the direction of alignment regulation by the fine slit pixel electrodes 1621 and 1622. A white arrow 1611 indicates the direction of alignment regulation by the gate line 1601 and the data line 1602.
[0053]
In the vicinity of the data line 1602, a fine slit pixel electrode 1622 is provided in the horizontal direction (perpendicular to the data line). In the vicinity of the gate line 1601, a fine slit pixel electrode 1621 is provided in the vertical direction (perpendicular to the gate line). As a connecting portion of these electrodes, the ITO electrode 1613 is extended vertically in the center of the pixel, and the ITO electrode 1623 is extended toward the intersection of the data line 1602 and the gate line 1601. The angle at which the ITO electrodes 1623 cross each other is 45 degrees. The ITO electrode 1613 is formed in a spine shape, and the orientation direction of the liquid crystal molecules on the ITO electrode 1613 is determined by the orientation of the liquid crystal molecules in the vicinity of the gate line 1601. Here, the electrode width of the fine electrodes 1621 and 1622 is about 3 μm, and the width of the slit between the electrodes 1621 and 1622 is also about 3 μm.
[0054]
In the fine electrodes 1621 and 1622, when a voltage is applied between the electrode on the TFT substrate and the electrode on the counter substrate, the direction in which the liquid crystal molecules fall is parallel to the direction in which the fine electrode extends. Become. This effect will be described with reference to FIGS. 17 (A) and 17 (B).
[0055]
FIG. 17A shows a case where the pixel electrode pattern is rough. A liquid crystal layer 1702 is provided between the counter substrate 1701 and the TFT substrate 1703. An ITO transparent electrode is formed on the entire surface of the counter substrate 1701. The electrode pattern interval on the TFT substrate 1703 is wide. In the region 1711, since the distance between the electrodes is wide, the liquid crystal molecules are tilted due to the inclination of the electric field. There is no mutual interference because the distance from the region that falls in the opposite direction is large, and the region falls in the left-right direction in the figure.
[0056]
FIG. 17B shows the case where the electrode pattern on the TFT substrate 1703 is fine. In the region 1721, since the gap between the electrodes is narrow, liquid crystal molecules that are about to fall due to the inclination of the electric field collide with each other and cannot fall. In order to escape from the stress, the liquid crystal molecules 1722 fall in a direction parallel to the electrodes (in the drawing, a direction perpendicular to the paper surface).
[0057]
This embodiment uses this principle. As shown in FIG. 16, in the portion where the fine electrode 1622 extending perpendicularly to the data line 1602 exists, the lateral electric field from the fine electrode 1622 and the data line 1602 The liquid crystal molecules fall laterally due to the influence. Here, since the alignment regulating direction of the fine electrode 1622 and the alignment regulating direction due to the lateral electric field from the data line 1602 coincide with each other, the liquid crystal molecules fall down in a straightforward manner. On the other hand, in the portion where the fine electrode 1621 extending in the direction perpendicular to the gate line 1601 exists, the liquid crystal molecules are tilted in the vertical direction due to the influence of the lateral electric field from the fine electrode 1621 and the gate line 1601. Here, since the alignment regulating direction of the fine electrode 1621 and the alignment regulating direction by the lateral electric field from the gate line 1601 coincide with each other, the liquid crystal molecules are tilted.
[0058]
As described above, since the alignment regulation on the liquid crystal molecules is straightforward, it is not necessary to provide a special structure such as a bank or a slit on the counter substrate side.
[0059]
FIG. 16 will be described in more detail. An ITO transparent electrode is provided in a pixel region surrounded by the gate line 1601 and the data line 1602, and a display voltage is applied by the TFT. The ITO electrode is patterned in a comb shape, and the direction of the comb is set to be perpendicular to the data line 1602 in the vicinity of the data line 1602 and perpendicular to the gate line 1601 in the vicinity of the gate line 1601. The comb teeth are connected to an electrode 1613 extending up and down the center of the pixel, and the electrode 1613 like a spine extends toward the intersection of the data line 1602 and the gate line 1601 and takes a Y shape. A good orientation could be obtained when the angle of spreading the Y-shaped hand was set between 30 and 120 degrees. Here, the width of the ITO electrode of the slit electrode was set to 3 μm to 5 μm, and the width of the ITO gap portion of the slit was set to 2 μm to 5 μm.
[0060]
FIG. 18 shows a case where the angle of spreading the hand is about 60 degrees. The length of the comb-like electrode 1821 extending in the vertical direction (perpendicular to the gate line 1801) is increased. In this case, the lateral electric field from the gate line 1801 can be used more effectively.
[0061]
19A to 19C are enlarged views of ITO electrode patterns.
FIG. 19A shows the simplest configuration, and the width of the comb-like ITO electrode is constant. In the region 1902, the liquid crystal molecules are tilted in the horizontal direction in the drawing, in the region 1903, the liquid crystal molecules are tilted in the vertical direction in the drawing, and in the region 1901, the liquid crystal molecules are tilted in a 45 ° diagonal direction in the drawing.
[0062]
In FIG. 19B, the direction of the comb-like electrode is inclined by an angle θ. The extending direction of the comb-like electrode extending upward from the spine with the hand spread was tilted from the upper direction to the arm extending the arm. That is, the comb-like electrode 1922 is an electrode in the vicinity of the gate line, and is inclined at an angle θ with respect to the longitudinal direction of the spine-like electrode 1921. The comb-like electrode 1923 is an electrode near the data line, and is inclined at an angle θ with respect to the vertical direction of the spine-like electrode 1921. The inclination angle θ was changed from 1 degree to 45 degrees.
[0063]
In the region 1911, the liquid crystal molecules are tilted in a 45 ° oblique direction in the figure. The inclinations of the liquid crystal molecules in the regions 1902 and 1903 in FIG. Since the difference between the tilts of the liquid crystal molecules in the regions 1912 and 1913 in FIG. 19B is smaller than 90 degrees, the tilt of the liquid crystal molecules changes gently between the regions 1911 to 1913.
[0064]
FIG. 19C shows a structure in the case where the shape of the electrode is tapered. Here, the angle θ of the tapered electrodes 1931 and 1932 was set to about 1 to 20 degrees. The effect of tapering the shape of the electrode will be described. FIG. 20A shows the case where the fine electrodes 2001 and 2002 are parallel. The liquid crystal molecules 2003 in the vicinity of the fine electrode 2001 and the liquid crystal molecules 2004 in the vicinity of the fine electrode 2002 are different in inclination by 180 degrees. FIG. 20B illustrates a case where the shapes of the fine electrodes 2011 and 2012 are tapered. The difference in tilt between the liquid crystal molecules 2013 near the fine electrode 2011 and the liquid crystal molecules 2014 near the fine electrode 2012 is smaller than 180 degrees. The inclination of the liquid crystal molecules 2013 to 2015 changes gently.
[0065]
FIGS. 21A and 21B show a configuration in the case of utilizing the Cs line for forming the auxiliary capacitance. FIG. 21A is a plan view of a liquid crystal display device. Similar to the gate line 2102 or the data line 2103, a horizontal electric field is formed from the Cs line 2104. This lateral electric field is actively utilized for orientation.
[0066]
The metal layer 2105 corresponds to the metal layer 811 in FIG. 8B and is connected to the ITO pixel electrode 2101. Here, similarly to the case shown in FIGS. 16, 18, and 19 (A) to (C), the tip of the comb-like electrode is placed on the electrode that causes the transverse electric field (FIG. 16, FIG. 18, In FIGS. 19 (A) to 19 (C), it is important to be directed to the data line or the gate line.
[0067]
In FIG. 21A, comb-like electrodes are extended vertically and horizontally in the upper half 2101a and the lower half 2101b of the pixel as comb-like electrodes.
[0068]
FIG. 21B is a cross-sectional view taken along line 2106 in FIG. An ITO pixel electrode 2121 is formed on the entire surface of the counter substrate 2111. On the TFT substrate 2112, a metal layer 2133 is formed on the Cs line 2134 with an insulating film 2132 interposed therebetween. The metal layer 2133 and the ITO pixel electrode 2131 are connected. The Cs line 2134 corresponds to the Cs line 2104 in FIG. 21A, and the metal layer 2133 corresponds to the metal layer 2105 in FIG. As described above, the oblique electric field 1341 generated from the Cs line 2134 can be positively utilized for orientation.
[0069]
As shown in FIG. 22, a backbone region may be provided in the ITO pixel electrode 2101 in each of the regions 2101a and 2101b.
[0070]
FIG. 23A shows an example in which the pixel electrode 2301 is extended to the upper right, upper left, lower left, and lower right. In addition to the pixel electrode 2301, a gate line 2302, a data line 2303, and a Cs line 2304 are formed on the TFT substrate. The pixel electrode 2301 includes an electrode 2305 parallel to the Cs line 2304.
[0071]
FIG. 23B shows a configuration in which the Cs line 2304 is actively used. In the pixel electrode 2311, regions 2311 a and 2311 b having different orientations are formed in a cross shape in the upper half and the lower half of each pixel. The regions 2311 a and 2311 b are connected by a pixel electrode 2312.
[0072]
In FIG. 21A, a transparent electrode for transmitting the voltage from the TFT across the Cs line 2104 is provided. Here, the ITO transparent electrode 2101 is set to extend on the Cs line 2104 on the Cs line 2104. Thereby, the auxiliary capacity was realized.
[0073]
FIG. 24 shows a configuration in which the liquid crystal panel is sandwiched between a pair of λ (wavelength) / 4 plates. A liquid crystal panel 2403 is sandwiched between λ / 4 plates 2402 and 2404, and both sides thereof are sandwiched between polarizing plates 2401 and 2405. The absorption axis 2411 of the polarizing plate 2401 is shifted by 45 degrees with respect to the horizontal direction in the figure. The optical axis 2412 of the λ / 4 plate 2402 is shifted by 90 degrees with respect to the horizontal direction in the figure. The optical axis 2414 of the λ / 4 plate 2404 is in the same direction as the horizontal direction in the figure. The absorption axis 2415 of the polarizing plate 2405 is shifted by 135 degrees with respect to the horizontal direction in the figure. The polarizing plates 2401 and 2405 absorb the light components of the absorption axes 2411 and 2415, respectively. The λ / 4 plates 2402 and 2404 perform conversion between linearly polarized light and circularly polarized light and output it. The luminance is improved by sandwiching the liquid crystal panel 2403 between the pair of λ / 4 plates 2402 and 2404.
[0074]
FIG. 25A has the same configuration as FIG. 23B, and the transmitted light amount distribution of the upper half pixel region 2311a is shown in FIGS. FIG. 25B shows a distribution in the case where there is no λ / 4 plate, and a cross-shaped black region is generated in the pixel. This is because the liquid crystal molecules are inclined in a direction perpendicular or parallel to the optical axis of the polarizing plate. FIG. 25C shows the distribution when the λ / 4 plates 2402 and 2404 are applied as shown in FIG. 24. The black region is only in the center of the pixel, and a bright display is realized.
[0075]
According to the present embodiment, as shown in FIG. 16, the pixel electrode is a pixel electrode having a comb shape or a slit shape, and the direction of the comb teeth extends toward the gate line in the vicinity of the gate line 1601. In the vicinity of the data line 1602, it extends toward the data line.
[0076]
As shown in FIG. 21A, the CS line (auxiliary capacitor forming electrode line) 2104 extends in the horizontal direction at the center of the pixel. The pixel electrodes are divided into upper and lower portions with the auxiliary capacitance forming electrode line 2104 as a boundary, and in the vicinity of the auxiliary capacitance forming electrode line 2104, the auxiliary capacitance forming electrode line is overlapped with the auxiliary capacitance forming electrode line. Extends in the same direction.
[0077]
In addition, as shown in FIG. 16, the pixel electrode has a vertical electrode 1613 formed in a spine shape at the center of the pixel, and a comb-like electrode 1621 toward the gate line 1601 and a comb-tooth toward the data line 1602. An electrode portion 1623 connected to the electrode 1622 has a Y-shaped arm shape extending from the spine-shaped electrode 1613 in all directions.
[0078]
As shown in FIG. 21A, the pixel electrode extends toward the auxiliary capacitance forming electrode line in the vicinity of the auxiliary capacitance forming electrode line 2104 in the direction of the comb teeth. The pixel electrode includes a Y-shaped arm-shaped electrode that connects the comb-shaped electrode toward the auxiliary capacitance forming electrode line 2104 and the comb-shaped electrode toward the data line 2103, and a comb-shaped electrode toward the gate line 2102. A Y-shaped arm-shaped electrode connecting the comb-shaped electrode toward the data line 2103;
[0079]
The angle formed by the arms of the Y-shaped arm-shaped electrode is preferably 30 degrees or more and 150 degrees or less. Further, as shown in FIG. 19B, the pixel electrode extends in the direction of the comb-shaped electrode 1922 extending toward the gate line, and inclines toward the data line in the vicinity of the data line. In the vicinity of the gate line, the comb-shaped electrode 1923 extending toward the line is inclined toward the gate line. Further, as shown in FIG. 19C, the pixel electrode has a comb-teeth shape, and the tip portion of the tooth is narrower or narrower.
[0080]
As shown in FIG. 21A, in the pixel electrode, an electrode provided for transmitting a voltage from the drain of the thin film transistor across the auxiliary capacitance forming electrode line 2104 is provided in the vicinity of the auxiliary capacitance forming electrode line 2104. And extend in the same direction so as to overlap the auxiliary capacitance forming electrode line.
As shown in FIG. 24, a pair of orthogonal quarter-wave plates 2402 and 2404 sandwich a liquid crystal panel (a pair of substrates sandwiching a liquid crystal layer) 2403.
[0081]
As described above, by using this embodiment, a bright display can be realized and a liquid crystal display with a wide viewing angle can be realized.
[0082]
(Third embodiment)
In order to further improve the viewing angle characteristics of the MVA type liquid crystal display device, a film configuration as shown in FIG. 26 has been proposed. The liquid crystal layer 2605 is sandwiched between a pair of retardation films 2604 and 2606 having an in-plane retardation. Further, both sides thereof are sandwiched between a pair of negative retardation films 2603 and 2607. Further, both sides thereof are sandwiched between a pair of polarizers 2602 and 2608. Further, both sides are sandwiched between a pair of protective layers 2601 and 2609. The absorption axis 2612 of the polarizer 2602 and the absorption axis 2618 of the polarizer 2608 are shifted by 90 degrees. The optical axis 2614 of the retardation film 2604 and the optical axis 2616 of the retardation film 2606 are shifted by 90 degrees. The absorption axis 2612 of the polarizer 2602 and the optical axis 2614 of the retardation film 2604 are shifted by 90 degrees. As a viewing angle characteristic, a range of contrast 10 or more is realized with an inclination angle of ± 80 degrees or more in all directions. However, the brightness cannot be improved.
[0083]
On the other hand, as a technique for improving luminance, a technique using a circularly polarizing plate as shown in FIG. 27 has been proposed. The liquid crystal panel 2706 has a liquid crystal layer sandwiched between two substrates, and is sandwiched between a pair of triacetyl cellulose (TAC) 2705 and 2707. Further, both sides are sandwiched between a pair of λ / 4 films 2704 and 2708. Further, both sides are sandwiched between a pair of TACs 2703 and 2709. Further, both sides thereof are sandwiched between a pair of polyvinyl alcohol (PVA) polarizing layers 2702 and 2710. Further, both sides are sandwiched between a pair of TACs 2701 and 2711.
[0084]
The absorption axis 2722 of the polarizing layer 2702 is shifted by 90 degrees with respect to the horizontal direction in the figure. The optical axis 2724 of the λ / 4 film 2704 is shifted by 45 degrees with respect to the horizontal direction in the figure. The optical axis 2728 of the λ / 4 film 2708 is shifted by 135 degrees with respect to the horizontal direction in the figure. The absorption axis 2730 of the polarizing layer 2710 is in the same direction as the horizontal direction in the figure.
[0085]
According to this configuration, although the luminance is improved by 20% to 50%, the viewing angle characteristic realized by the configuration shown in FIG. 26 cannot be obtained. Although the range of contrast 10 or more in the vertical and horizontal directions is ± 80 degrees, it remains at ± 50 degrees in the 45 ° oblique direction.
[0086]
The embodiment of the present invention has a configuration having both of the characteristics shown in FIGS.
FIG. 28A shows the simplest principle configuration in the present embodiment. The λ (wavelength) / 2 plate 2802 is sandwiched between a pair of polarizing layers 2801 and 2803. The absorption axis 2811 of the polarizing layer 2801 is in the same direction as the horizontal direction in the figure. The optical axis 2812 of the λ / 2 plate 2802 is also in the same direction as the horizontal direction in the figure. The absorption axis 2813 of the polarizing layer 2803 is shifted by 90 degrees with respect to the horizontal direction in the figure. The λ / 2 plate 2802 converts the incident linearly polarized light into linearly polarized light rotated by 90 degrees and emits it.
[0087]
The polarizing layers 2801 and 2803 indicate PVA polarizing layers. Generally, a polarizing plate is provided with a film of triacetyl cellulose (TAC) on both sides of the PVA polarizing layer, but indicates a state without this TAC film. A half-wave plate 2802 is provided between the pair of polarizing layers 2801 and 2803, and the phase difference in the direction perpendicular to the film of the half-wave plate 2802 ((nx + ny) / 2−nz) × d is zero. Here, nx, ny, and nz are the refractive indexes in each direction, and d is the thickness. The optical axis 2812 of the half-wave retardation plate 2802 is parallel or perpendicular to the absorption axes 2811 and 2813 of the adjacent polarizing layers 2801 and 2803. FIG. 28B shows the state of leakage light in this case, and it can be seen that there is almost no leakage light in all directions.
[0088]
The configuration of the entire liquid crystal panel was made substantially the same as this configuration. That is, an optical film and a liquid crystal layer are laminated on this structure, but they are canceled and become substantially the same as nothing, and as a result, substantially the same as FIG. It comprised so that it might become.
[0089]
FIG. 29A shows a case where a pair of quarter-wave films 2901 and 2902 are laminated so that their optical axes 2911 and 2912 are orthogonal to each other. The quarter-wave films 2901 and 2902 are inserted between the half-wave plate 2802 and the polarizing layer 2803. Here, the orientations of the optical axes 2911 and 2912 of the quarter-wave plates 2901 and 2902 are set to form an angle of 45 degrees with the absorption axes 2811 and 2813 of the polarizing layers 2801 and 2803. The negative phase difference of the quarter wave plates 2901, 2902 was also set to zero. Quarter wave plates 2901, 2902 convert between linearly polarized light and circularly polarized light. FIG. 29B shows the state of leaked light in this case, and it can be seen that the leaked light is very small in all directions.
[0090]
FIG. 30A further shows a liquid crystal layer 3001 that can be vertically aligned and a negative phase difference only in a direction perpendicular to the film surface.
((Nx + ny) / 2-nz) × d <0
A film 3002 having The vertically aligned liquid crystal layer 3001 has a refractive index anisotropy of a positive retardation liquid crystal only in a direction perpendicular to the liquid crystal layer 3001.
Δn × cell thickness d> 0
have. Here, the negative phase difference of the film 3002 and the positive phase difference of the liquid crystal layer 3001 are set to be the same so as to completely cancel each other optically. Δn is n // − n⊥, where n // is the refractive index in the longitudinal direction of the liquid crystal molecules, and n / is the refractive index in the direction perpendicular to the longitudinal direction of the liquid crystal molecules.
[0091]
The stack of the liquid crystal layer 3001 and the film 3002 is inserted between a pair of λ / 4 plates 2901 and 2902. Δn × d of the film 3002 is the same as that of the liquid crystal layer 3001. Δn of the film 3002 is nx−nz.
[0092]
When the configuration of FIG. 28A is adopted, light leakage from the crossed Nicols polarizing layers 2801 and 2803 is very small when viewed from any direction, but its operation will be described. Consider a case where the crossed Nicols polarizing layers 2801 and 2803 are observed obliquely. The absorption axes 2811 and 2813 of the polarizing layers 2801 and 2803 are orthogonal when viewed from the front. When viewed obliquely, from the direction a in FIG. 28A, the absorption axes 2811 and 2813 of the polarizing layers 2801 and 2803 are still orthogonal and light does not leak. On the other hand, when viewed from the b direction in FIG. 28A, the absorption axes 2811 and 2813 of the polarizing layers 2801 and 2803 are not orthogonal. This can be understood, for example, by observing two pencils orthogonally and observing them from the direction b. The function of the half-wave plate 2802 in FIG. 28A is to prevent the light from leaking by changing the polarization state of the incident light even in such a b direction. The angles of the absorption axes 2811 and 2813 of the polarizing layers 2801 and 2803 when viewed from the front while observing from the a direction are the upper left direction on the incident side, the upper right direction on the output side, and the optical axis of the half phase difference plate 2802 Reference numeral 2812 denotes an upper right direction. Here, when an inclination angle is added in the b direction, the absorption axis shifts from the upper left to the left in the incident side, and the absorption axis shifts from the upper right to the right in the output side. However, the optical axis of the half-wave plate 2802 whose negative phase difference is 0 does not move from the upper left direction. For this reason, the polarization direction of the incident light and the half phase difference plate 2802 form an angle in the b direction. And since it has a phase difference of a half wavelength, the polarization direction of the incident light is rotated, but it is output as a linearly polarized light from the phase difference plate 2802. The polarization direction of the emitted light coincides with the absorption axis direction of the polarization layer on the emission side and is completely absorbed. For this reason, as shown in FIG. 28 (B), there is almost no light leakage from any orientation.
[0093]
Next, the operation of the orthogonal λ / 4 plates 2901 and 2902 employed in FIG. 29A will be described. Since the phase difference in the direction perpendicular to the film surface is 0 as described when the half-wave retardation plate 2802 is described above, the direction of the optical axis is unchanged even when the tilt angle to be observed is set. It is. Therefore, the optical axes 2911 and 2912 of the λ / 4 plates 2901 and 2902 whose optical axes are orthogonal to each other at the front are orthogonal to each other when viewed from any orientation and inclination angle. For this reason, the effects as the λ / 4 plates 2901 and 2902 are canceled out and become the same as nothing.
[0094]
Next, an operation of the film 3002 having a negative retardation which is stacked with the liquid crystal layer 3001 in FIG. Here, the positive retardation of the vertically aligned liquid crystal layer 3001 and the negative retardation of the film 3002 are the same. The optical effects of the two layers in this relationship are completely offset and are the same as not. For this reason, the black display as a liquid crystal display is black from anywhere. FIG. 30A shows a liquid crystal panel in which the inside of a pixel is roughly divided into four types, and the liquid crystal is tilted to the upper right, upper left, lower left, and lower right as the voltage is applied. As shown in FIG. 30B, it can be seen that a contrast of 10 or more is realized in all directions.
[0095]
The λ / 4 plates 2901 and 2902 are set so that the optical axes 2911 and 2912 are orthogonal to each other and the absorption axes 2811 and 2813 of the polarizing layers 2801 and 2803 are oriented at 45 degrees. Equivalent to. It serves to convert linearly polarized light that has passed through the polarizing layer into circularly polarized light. In the description so far, each film and the vertically aligned liquid crystal layer cancel each other and have no optical effect, but the situation changes completely when a voltage is applied to the liquid crystal layer 3001. That is, white display is realized by the liquid crystal layer 3001 having an optical effect. The quarter-wave retardation plates 2901 and 2902 improve the brightness of white display at the front viewing angle as described in the above description.
[0096]
First, the half-wave retardation plate 2802 and the quarter-wave retardation plates 2901 and 2902 were realized by stretching a polycarbonate film or a norbornene film. As a stretching method, the film was stretched in-plane and pulled so that stress was applied in the vertical direction.
[0097]
Here, the half-wave retardation plate 2802 was also realized by stacking two quarter-wave retardation plates. Such a film is commercially available from Nitto Denko Corporation under the name of NZ film and from Sumitomo Chemical Co., Ltd. under the name of SZ film.
[0098]
The film 3002 having a negative retardation is realized by stretching a polycarbonate or norbornene-based film in two directions, or coating a resin on a film having no optical effect. Such a film is also commercially available from Nitto Denko Corporation, and is also marketed by Sumitomo Chemical Co., Ltd. under the name of VAC film.
[0099]
As the liquid crystal panel 3001, an MVA type liquid crystal panel commercially available from Fujitsu Limited was used. As for the alignment direction, one pixel is roughly divided into four types of regions, and the liquid crystal molecules are inclined to the upper right, upper left, lower left, and lower right when voltage is applied.
[0100]
As for the polarizing plates 2801 and 2803, a triacetyl cellulose (TAC) film is usually used as a holding material for the polarizing plate. However, if this TAC film is present between the polarizing layers 2801 and 2803 and the liquid crystal layer 3001, the optical properties of the polarizing plate Effects will have a negative effect. For this reason, when the films are laminated, this holding material is used only on one side and is not set on the liquid crystal layer side. In fact, such a polarizing plate having a TAC film provided only on one side of the polarizing layer is commercially available, for example, as an ultra-thin-polarizer from Sumitomo Chemical Co., Ltd. The film configuration shown in FIG. 30A was realized by laminating an optical film on this polarizing plate.
[0101]
FIG. 30B shows a calculation example of viewing angle characteristics when the above-described film and liquid crystal layer are laminated as shown in FIG.
In the configuration of FIG. 30A, the viewing angle characteristic is as shown in FIG. 30B, but the direction with particularly high contrast is the upper right, the upper left, the lower left, and the right as is clear from FIG. It is a downward direction. A wide viewing angle in the vertical and horizontal viewing directions is particularly required, and the configuration shown in FIG. 31A corresponds to this. Here, the direction of the absorption axis of the polarizing layer and the direction of the optical axis of the film were rotated 45 degrees from FIG. FIG. 31B shows the calculation result of the viewing angle characteristic at this time. The contrast is 10 or more in all directions, and the viewing angle characteristics are vertically and laterally symmetrical, and the viewing angle range in the vertical and horizontal directions is particularly wide. As a result, it is possible to realize a display that is bright and satisfactory as a viewing angle characteristic.
[0102]
FIG. 32 shows measured values of the viewing angle characteristics of the prototyped liquid crystal panel. Since the film characteristics were not perfect, the characteristics were different from the calculation, but a wide viewing angle could be obtained. At the same time, the display brightness of white on the front side could be improved by 20% compared to the case where no film was applied.
[0103]
The description so far has been made on the assumption that the λ / 2 plate 2802 of FIG. 28A is used, but better viewing angle characteristics can be obtained by using a laminate of a pair of special λ / 2 plates. This arrangement is reported by Tohoku University at SID00.
[0104]
Two films having a half-wave retardation are laminated, the refractive index in the direction perpendicular to the film surface is nz, the refractive index in the direction parallel to the optical axis of the film is nx, and the optical axis of the film is Let ny be the refractive index in the vertical film in-plane direction,
Nz coefficient = (nx−nz) / (nx−ny)
Are laminated with the optical axis parallel to each other, and the slow axis of the film is set parallel or perpendicular to the absorption axis of the adjacent polarizing layer. This arrangement was applied instead of FIG. 28A, and films and liquid crystal layers were arranged as shown in FIGS. 29A, 30A, and 31A.
[0105]
Furthermore, the values of (nx−nz) / (nx−ny) of the two films are 0.5 or less and 0.5 or more, respectively, preferably 0.25 and 0.75, or 0. If the sum is about 1, such as 15 and 0.85, similar good light leakage characteristics can be obtained.
[0106]
The negative retardation of the film described above is difficult to make the negative retardation completely zero in the λ / 2 plate and λ / 4 plate. It has been found that good viewing angle characteristics can be obtained if the range of the negative phase difference is ± 20 nm or less, preferably ± 10 nm or less.
[0107]
According to the present embodiment, as shown in FIG. 31 (A), the half-wave plate 2802 is formed by laminating films having a half-wave phase difference and in a direction perpendicular to the film surface. ((Nx + ny) / 2−nz) × d (the refractive index in the direction perpendicular to the film surface is nz, the refractive index in the direction parallel to the optical axis of the film is nx, the in-plane direction of the film perpendicular to the optical axis of the film) The refractive index is ny and the film thickness is d) is 0 or ± 20 nm or less, and the optical axis of the film is parallel or perpendicular to the absorption axis of the adjacent polarizing layer 2801.
[0108]
In addition, the half-wave plate 2802 is formed by laminating two films having a half-wave retardation, the refractive index in the direction perpendicular to the film surface is nz, and the direction parallel to the optical axis of the film is When the refractive index is nx and the refractive index in the in-plane direction perpendicular to the optical axis of the film is ny, the values of (nx−nz) / (nx−ny) of the two films are 0.5 or less and 0.00 respectively. 5 or more, the optical axes of the two films may be parallel, and may be parallel or perpendicular to the absorption axis of the adjacent polarizing layer 2801.
[0109]
The film 3002 has Δn × d (Δn is n // − n⊥, where n // is the refractive index in the longitudinal direction of the liquid crystal molecules, and n 液晶 is perpendicular to the longitudinal direction of the liquid crystal molecules. A negative phase difference of the same size as that of the liquid crystal layer 3001.
[0110]
The pair of quarter-wave plates 2901 and 2902 has a negative phase difference of 0 or ± 10 nm or less, and is provided so as to sandwich the liquid crystal layer 3001 and the film 3002. The optical axes of the pair of quarter wave plates 2901 and 2902 are orthogonal to each other, and form an angle of 45 degrees with the absorption axes of the pair of polarizing layers 2801 and 2803. The direction of the absorption axis of the polarizing layer on the light incident side is set to 0 degree, 45 degrees, 90 degrees, or 135 degrees with the right side of the screen as 0 degrees.
[0111]
As shown in FIG. 31 (A), while maintaining the optical axis relationship between the light incident side polarization layer, the light exit side polarization layer, the quarter wavelength plate, and the half wavelength plate in FIG. The direction of the absorption axis of the polarizing layer is adjusted so that the direction in which the contrast is maximized is the vertical, horizontal, and horizontal directions.
[0112]
The liquid crystal layer 3001 is aligned such that liquid crystal molecules are vertically aligned when no voltage is applied, and the liquid crystal molecules are largely inclined in two or more directions in a pixel when a voltage is applied. Preferably, the liquid crystal layer 3001 is largely divided into four types of liquid crystal molecules in a pixel in a voltage application state, upper right, upper left, lower left, lower right, and slits provided on the electrodes and / or protrusions provided on the electrodes. The orientation of the liquid crystal is controlled using an object (bank).
[0113]
As described above, by using this embodiment, a bright liquid crystal display with a wide viewing angle can be realized.
[0114]
(Fourth embodiment)
In order to further improve the viewing angle characteristics of the MVA type liquid crystal display device, a film configuration as shown in FIG. 33 has been proposed. The liquid crystal layer 3304 is sandwiched between a pair of retardation films 3303 and 3305 having an in-plane retardation. Further, both sides thereof are sandwiched between a pair of negative retardation films 3302 and 3306. Further, both sides thereof are sandwiched between a pair of polarizing plates 3301 and 3307. The absorption axis 3311 of the polarizing plate 3301 and the absorption axis 3317 of the polarizing plate 3307 are shifted by 90 degrees. The optical axis 3313 of the retardation film 3303 and the optical axis 3315 of the retardation film 3305 are shifted by 90 degrees. The absorption axis 3311 of the polarizing plate 3301 and the optical axis 3313 of the retardation film 3303 are shifted by 90 degrees.
[0115]
As a viewing angle characteristic, a range of contrast 10 or more is realized with an inclination angle of ± 80 degrees or more in all directions. However, two films are used, and the refractive index of the film
nx>ny> nz
A special film with a relationship of
[0116]
As shown in FIG. 34, the embodiment of the present invention realizes a display having good viewing angle characteristics without using such a special film. In this embodiment, as a film added to the polarizing plates 3401 and 3404, only one film 3402 is used, and the refractive index of the film 3402 is also set.
nx>nz> = ny
A film having a relationship of
[0117]
As the polarizing plates 3401 and 3404, the thickness of the entire polarizing plate was set to 100 microns or more. On the other hand, the in-plane retardation (nx−ny) × d of the film was set to 40 nm or more and 140 nm or less (preferably 40 nm or more and 130 nm or less).
[0118]
The phase difference when the liquid crystal layer 3403 is vertically aligned is
RLC = (n // − n⊥) × d
And
[0119]
The sum of the negative retardation of the protective film layers of the polarizing plates 3401 and 3404, the negative retardation of the film 3402 having an in-plane retardation, and the negative retardation of other layers having a negative retardation.
R negatototal
When
20 nm <RLC-R negatototal <150 nm
Set to. As a result, it was possible to realize ± 70 degrees or more as an inclination angle capable of ensuring a contrast of 10 or more in all viewing angle directions.
[0120]
The in-plane retardation of the film 3402 having the in-plane retardation functions to rotate the polarization direction of the polarized light. A film having a negative retardation in a direction perpendicular to the layer functions to cancel the positive retardation of the liquid crystal layer 3403. And the positive phase difference as a difference that is not completely canceled
RLC-R negatototal
Has a function of adjusting the ellipticity from linearly polarized light to elliptically polarized light. Also, it acts to change the rotation direction of the polarization of elliptically polarized light.
[0121]
As the refractive index of the film 3402
nx>nz> = ny
The film having the above relationship was realized by stretching a norbornene-based resin film in one direction.
[0122]
Thick polarizing plates 3401 and 3404 have been conventionally used and have a protective film made of triacetyl cellulose and have a thickness of 100 μm or more.
[0123]
The retardation film 3402 and the liquid crystal layer 3404 are sandwiched between a pair of polarizing plates 3401 and 3404. The absorption axis 3411 of the polarizing plate 3401 and the optical axis 3412 of the adjacent retardation film 3402 were orthogonal to each other. The absorption axis 3411 of the polarizing plate 3401 and the absorption axis 3414 of the polarizing plate 3404 are orthogonal to each other.
[0124]
In FIG. 35, the film 3503 having an in-plane retardation of 40 to 130 nm (preferably 60 to 110 nm) is used as a protective film for the polarizing plate 3510. The polarizing plate 3510 is formed by stacking a protective film 3501, a polarizing layer 3502, and a retardation film / protective film 3503. A liquid crystal layer 3504 is sandwiched between polarizing plates 3510 and 3505. The polarizing layer 3502, the retardation film / protective film 3503, the liquid crystal layer 3504, and the polarizing plate 3505 correspond to the polarizing plate 3401, the retardation film 3402, the liquid crystal layer 3403, and the polarizing plate 3404 in FIG.
[0125]
Since the retardation film 3503 also serves as a protective film for the polarizing plate 3510, the total number of films used can be reduced, and the cost can be reduced. The negative retardation of this film was also adjusted so as to satisfy the above-described retardation relationship.
[0126]
As a film having a negative retardation, for example, a norbornene-based resin was stretched in two or more directions.
[0127]
FIG. 36 shows a generalized configuration, and the lower polarizing plate 3505 in FIG. 35 is changed. A polarizing plate 3610 is used instead of the polarizing plate 3505. The polarizing plate 3610 is formed by stacking a film 3601, a polarizing layer 3602, and a protective film 3603. The absorption axis 3612 of the polarizing layer 3602 is in the same direction as the absorption axis 3515 of the polarizing plate 3505 in FIG.
[0128]
The film 3601 can also have an in-plane retardation. In that case, the optical axis was set perpendicular to the absorption axis 3612 of the adjacent polarizing layer 3602. Further, the in-plane retardation of the film 3601 can be made almost zero. It is also possible to use a film having no in-plane retardation and having only a negative retardation.
[0129]
According to the present embodiment, in FIG. 34, the liquid crystal layer 3403 can have liquid crystal molecules vertically aligned. The retardation film 3402 is a retardation film having an in-plane retardation, and is provided so that its optical axis is perpendicular to the absorption axis of the adjacent polarizing layer 3411, and its refractive index is nx>nz> =. ny (nx is the refractive index in the optical axis direction, ny is the refractive index in the in-plane direction perpendicular to nx, and nz is the refractive index in the direction perpendicular to the surface). The first polarizing plate 3401 is provided with a protective film having a thickness of 100 microns or more. The retardation film 3402 has an in-plane retardation (nx−ny) × d (d is a thickness) of 40 nm to 140 nm, preferably 40 nm to 130 nm.
[0130]
The liquid crystal layer 3403 has a retardation RLC = (n // − n∥) × d (n // is a refractive index in the longitudinal direction of the liquid crystal molecules, and n⊥ is a longitudinal direction of the liquid crystal molecules. The refractive index in the direction perpendicular to the direction, d is the thickness), the negative retardation of the protective film of the polarizing plate 3401, the negative retardation of the retardation film 3402, and other negative When a layer having a phase difference is applied, the relationship of 20 nm <RLC-Rnegate <150 nm is established when the sum of the negative phase differences is defined as R negatototal. The polarizing plate 3411 includes a protective film of triacetyl cellulose, norbornene resin, or polycarbonate.
[0131]
In FIG. 35, the polarizing plate 3510 includes a protective film 3503 having an in-plane retardation. The protective film 3503 is provided so that the optical axis of the protective film 3503 is perpendicular to the absorption axis of the polarizing layer 3502. In-plane retardation (nx−ny) × d (nx is the refractive index in the optical axis direction, ny is the refractive index in the in-plane direction perpendicular to nx, and d is the thickness) of the protective film 3503 (preferably 40 nm to 140 nm) Is 40 nm or more and 130 nm or less), and when two protective films are used, the sum of the in-plane retardation of the two sheets is set to 40 nm or more and 140 nm or less (preferably 40 nm or more and 130 nm or less).
[0132]
The liquid crystal layer 3504 has a retardation RLC = (n // − n⊥) × d when liquid crystal molecules are vertically aligned, and a layer having a negative retardation of the protective film 3503 and other negative retardation is applied. In this case, when the sum of the negative phase differences is defined as R negative total, the relationship is 20 nm <RLC−R negative total <150 nm.
[0133]
As described above, by using this embodiment, a bright liquid crystal display with a wide viewing angle can be realized.
[0134]
(Fifth embodiment)
In order to realize a wide viewing angle, the MVA liquid crystal display device is vertically oriented when no voltage is applied, and when a voltage is applied, the MVA liquid crystal display device is divided into four regions and each tilts in four directions. As a result of the mixing of the viewing angle characteristics of each region, a wide viewing angle can be obtained. In such a case, since the boundary of the alignment region becomes black, there has been a problem that white display luminance is not high. In view of this, a method for realizing bright display only in two divisions has been studied.
[0135]
FIG. 37 shows an example of the orientation method of a two-divided liquid crystal display device. On the TFT substrate, a gate line 3701, a data line 3702, a Cs line 3703, and an ITO pixel electrode 3704 are formed. As indicated by thick arrows 3711 and 3712, the orientation is divided by a Cs line 3703 running in the center of the pixel and a gate line 3701. The alignment boundary is hidden by the gate line 3701 and the Cs line 3703. Such a two-divided display has a problem that the viewing angle is narrower than that of the four-divided display. In particular, coloring at an oblique viewing angle becomes a problem.
[0136]
FIG. 38A shows the orientation and the like. As shown by arrows 3711 and 3712, a case where liquid crystal molecules are divided and aligned so as to fall in the vertical direction in the figure is taken as an example. The absorption axis 3811 of the analyzer (polarizing plate) and the absorption axis 3812 of the polarizer (polarizing plate) are orthogonal and provided in the direction of FIG. In this display, when no voltage is applied, the liquid crystal molecules are vertically aligned, and the display is black. On the other hand, when a voltage is applied, the liquid crystal molecules are tilted in the vertical direction in the figure, and light is transmitted by the birefringence of the liquid crystal, resulting in a white display.
[0137]
Here, a case where the observer 3801 observes the display from the vertical direction will be described. FIG. 38B is a cross-sectional view of FIG. 38A viewed from the left-right direction. The length 3822 of the liquid crystal molecules 3821 looks short when viewed from the observer 3801. For this reason, the substantial birefringence of the liquid crystal is reduced, and the white display is slightly darkened or bluish.
[0138]
On the other hand, in FIG. 38A, a case where the viewer 3802 observes the display from the left and right directions will be described. FIG. 38C is a cross-sectional view of FIG. 38A as viewed from above and below. The optical path 3822 of the liquid crystal layer viewed by the observer 3802 is longer than the optical path 3833 when the liquid crystal layer is observed from the front. In this case, the birefringence of the liquid crystal itself does not change, but the birefringence of the liquid crystal layer increases because the optical path becomes longer. For this reason, there has been a problem in that the display changes from white to yellowish.
[0139]
The embodiment of the present invention aims to reduce these bluish or yellowish phenomena. "Technology using a combination of cholesteric layer and λ / 4 layer" has been proposed to increase the brightness of the backlight, but it is possible to use the color at the oblique viewing angle by utilizing the color at the oblique viewing angle. The main point of this embodiment is to reduce the amount.
[0140]
As shown in FIG. 39, the liquid crystal alignment directions 3711 and 3712 are opposite to each other. The absorption axis 3901 of the polarizing plate on which the cholesteric reflective layer is laminated is orthogonal to the absorption axis 3902 of the analyzer. The optical axis 3903 of the λ / 4 retardation layer is inclined 45 degrees with respect to the absorption axes 3901 and 3902 described above. The optical axis 3903 of the λ / 4 layer adjacent to the cholesteric layer was set to be perpendicular to the alignment directions 3711 and 3712 of the liquid crystal molecules.
[0141]
As shown in FIG. 41A, in a liquid crystal display device, a backlight 4101, a cholesteric layer 4102, a λ / 4 plate 4103, and a liquid crystal layer (including a polarizing plate) 4104 are stacked in this order. The cholesteric layer 4102 and the λ / 4 plate 4103 adjacent thereto will be described. The cholesteric layer 4102 reflects the counterclockwise circularly polarized light 4122 as the counterclockwise circularly polarized light 4123 out of the light incident from the backlight 4101, and passes the clockwise circularly polarized light 4121 as the clockwise circularly polarized light 4131. Then, the counterclockwise circularly polarized light 4123 reflected by the cholesteric layer 4102 is reflected as clockwise circularly polarized light 4124 by the reflector of the backlight 4101, and is incident on the cholesteric layer 4102 again and passes therethrough. That is, the cholesteric layer 4102 converts incident natural light into clockwise circularly polarized light 4131 in cooperation with the backlight 4101. The λ / 4 plate 4103 has a function of converting incident circularly polarized light into linearly polarized light. The λ / 4 plate will be described with reference to FIGS. 40 (A) and 40 (B).
[0142]
FIG. 40A shows a case where the optical axis 4002 of the λ / 4 plate 4001 is oriented in the depth direction in the figure. The λ / 4 plate 4001 receives circularly polarized light 4012 and 4022 and emits linearly polarized light 4013 and 4023, respectively. An observer 4011 from the front receives light 4013 and an observer 4021 from an oblique direction receives light 4023.
[0143]
When the λ / 4 plate 4001 is a uniaxial optical film, light 4023 emitted to an oblique observer 4021 having an orientation perpendicular to the optical axis 4002 of the λ / 4 plate 4001 is generally yellowish. In this direction, the optical path length (C-D in the figure) of the circularly polarized light 4022 that is incident obliquely becomes longer than the optical path length (A-B in the figure) of the circularly polarized light 4012 that enters perpendicularly. Birefringence increases. For this reason, in a system that is adjusted to be white with no color at the front, the birefringence becomes excessive at an oblique viewing angle, and the system is colored yellow. This phenomenon corresponds to the phenomenon shown in FIG.
[0144]
FIG. 40B shows a case where the optical axis 4032 of the λ / 4 plate 4031 is oriented in the horizontal direction in the figure. The λ / 4 plate 4031 receives circularly polarized light 4042 and 4052 and emits linearly polarized light 4043 and 4053, respectively. An observer 4041 from the front receives light 4043, and an observer 4051 from an angle receives light 4053.
[0145]
The light 4053 emitted obliquely in the direction parallel to the optical axis 4032 of the λ / 4 plate 4031 is generally bluish. In this orientation, the anisotropy of the refractive index itself at an oblique viewing angle is small, and the optical path length is long, but the birefringence effect is small. For this reason, the birefringence at an oblique viewing angle is insufficient, and the color becomes blue. This phenomenon corresponds to the phenomenon shown in FIG.
[0146]
Considering the liquid crystal layer 4104 in FIG. 41A, the direction of the optical axis of the above λ / 4 plate is read as the direction in which liquid crystal molecules are aligned, and is read as having a phase difference of λ / 2. Can be interpreted as linearly polarized light passing through the polarizer, and the same can be said for coloring. That is, the phenomenon of FIGS. 38B and 38C occurs.
[0147]
41A and 41B show the overall structure of a liquid crystal layer (including a polarizing plate) 4104, a λ / 4 plate 4103, a cholesteric layer 4102, and a backlight 4101, and the optical axis 4111 of the λ / 4 plate 4103, respectively. , 4151 and the optical axes 4112 and 4152 of the liquid crystal molecules of the liquid crystal layer are set perpendicular to each other. 41A shows a case where the image is observed from the upper or lower direction of FIG. 39, and FIG. 41B shows a case where the image is observed from the right or left direction.
[0148]
First, FIG. 41A will be described. The front observer 4133 receives light 4132 emitted from the light 4131 via the λ / 4 plate 4103 and the liquid crystal layer 4104. The oblique observer 4143 receives light 4142 emitted from the light 4141 through the λ / 4 plate 4103 and the liquid crystal layer 4104. The light 4142 passing through the λ / 4 plate 4103 adjacent to the cholesteric layer 4102 is yellowish due to the effect of increasing the optical path length. This phenomenon corresponds to the phenomenon shown in FIG. Next, the light 4142 passes through the liquid crystal layer 4104, but becomes bluish because the substantial birefringence of the liquid crystal is reduced. This phenomenon corresponds to the phenomenon shown in FIG. As described above, the influence of the λ / 4 plate 4103 (yellow tint) and the influence of the liquid crystal layer 4104 (blue tint) are offset, and a display with little color is realized.
[0149]
FIG. 41B shows a case where the image is observed from an orientation 90 degrees different from that in FIG. The front observer 4163 receives light 4162 emitted from the light 4161 via the λ / 4 plate 4103 and the liquid crystal layer 4104. The oblique observer 4173 receives light 4172 emitted from the light 4171 via the λ / 4 plate 4103 and the liquid crystal layer 4104. The light 4172 passing through the λ / 4 plate 4103 adjacent to the cholesteric layer 4102 is bluish because the substantial birefringence of the λ / 4 plate 4103 is reduced. This phenomenon corresponds to the phenomenon shown in FIG. Next, this light 4172 passes through the liquid crystal layer 4104, but becomes yellowish due to the effect of increasing the optical path length. This phenomenon corresponds to the phenomenon shown in FIG. As described above, the influence of the λ / 4 plate 4103 (yellow tint) and the influence of the liquid crystal layer 4104 (blue tint) are offset, and a display with little color is realized.
[0150]
In this way, good display is realized by canceling out the coloring of the liquid crystal layer 4104 and the coloring of the λ / 4 plate 4103.
[0151]
FIG. 37 shows an alignment state when performing a typical two-part alignment. A pixel area surrounded by the gate line 3701 and the data line 3702 was set. Each pixel is provided with a TFT. The liquid crystal molecules are vertically aligned when no voltage is applied. The direction in which the liquid crystal molecules tilt with voltage application was controlled by pretilt by irradiation of the alignment film surface with ultraviolet rays or rubbing of the alignment film surface. The direction in which the liquid crystal molecules are tilted is set in a direction perpendicular to the gate line 3701 so that the liquid crystal molecules are tilted so that the arms are widened as viewed from the gate line 3701.
[0152]
FIG. 39 shows the orientation directions 3711 and 3712 with respect to the TFT-LCD, the absorption axes 3901 and 3902 of the polarizing plate, and the optical axis 3903 of the λ / 4 retardation plate. 41A and 41B, as the λ / 4 retardation plate 4103, a film obtained by stretching polycarbonate is used. The birefringence value at 550 nm was set in the range of 137.5 nm ± 10 nm. As the cholesteric liquid crystal layer 4102, a TAC film was used as a substrate film. The pitch of the cholesteric liquid crystal is set so as to include a range that reflects visible light and further includes an infrared region. As a result, the reflection wavelength from the cholesteric liquid crystal layer 4102 was able to be realized with no significant change even at an oblique tilt angle. As the twist direction of the cholesteric layer 4102, a right twisted one was used. The cholesteric liquid crystal layer 4102 was formed by applying it several times, and drying and curing the individual layers at room temperature.
[0153]
FIG. 39 is a plan view, and the cross-sectional configuration will be described with reference to FIGS. 41 (A) and 41 (B). A side edge type was used as the backlight 4101. When viewed from the backlight 4101, a cholesteric liquid crystal layer 4102, a λ / 4 plate 4103, a polarizer 4104, a liquid crystal panel 4104, and an analyzer 4104 are stacked in this order. The Δn × d of the liquid crystal layer was set in the range of 200 nm to 400 nm.
[0154]
It was effective to provide a light scattering layer between the λ / 4 plate 4103 and the liquid crystal substrate 4104. The configuration is shown in FIG. A λ / 4 plate 4202 and a scattering layer 4203 are stacked on the cholesteric layer 4201. The scattering layer 4203 was realized by mixing a scattering material in an adhesive that bonds the λ / 4 plate 4202 and the polarizing plate. As the scattering property, a haze value of 40 or more was applied.
[0155]
FIG. 43 shows a measurement result of viewing angle characteristics when the present embodiment is actually applied. The coloration of white display was measured in increments of 15 degrees in all directions at an inclination angle of 70 degrees from the front. A region 4301 is red, a region 4302 is yellow, a region 4303 is green, a region 4304 is blue, and a central region thereof is white.
[0156]
The graph shown by rhombuses is a case of a panel with a vertically divided orientation (noted as normal in the figure) in which the cholesteric layer 4102 and the λ / 4 plate 4103 are not used, and a yellow colored phenomenon is observed. The graph shown by the square is the case without the scattering layer shown in FIGS. 41A and 41B (indicated in the figure as having no scattering layer). The graph indicated by the triangle is a liquid crystal panel to which the configuration (with a scattering layer in the figure) provided with the scattering layer shown in FIG. 42 is applied, and coloring can be reduced in any viewing angle direction.
[0157]
The above is the case of vertical alignment with no voltage applied, but here, an embodiment applied to a horizontal alignment display will be described. FIGS. 44A and 44B show an example of application to an IPS (in-plane switching mode) liquid crystal display.
[0158]
FIG. 44A is a cross-sectional view of an IPS liquid crystal display. A liquid crystal layer 4402 is provided between the counter substrate 4401 and the TFT substrate 4403. A common electrode 4412 and a drain electrode 4411 are formed on the TFT substrate 4403 with an insulating film 4413 interposed therebetween. The counter substrate 4401 is not provided with an electrode. When a voltage is applied to the drain electrode 4411, an electric field is generated between the drain electrode 4411 and the common electrode (ground potential).
[0159]
FIG. 44B is a plan view of the TFT substrate 4403 of the liquid crystal display of FIG. A gate line 4421, a data line 4422, a drain electrode 4423, and a common electrode 4424 are formed on the TFT substrate. When no voltage is applied, the liquid crystal molecules 4432 are oriented in the direction of 15 degrees clockwise with respect to the direction in which the drain electrode 4423 extends. The absorption axis (polarizer absorption axis) 4442 of the polarizing plate on the light incident side was set to be perpendicular to the alignment direction of the liquid crystal molecules 4432 with no voltage applied. As the voltage is applied, the alignment of the liquid crystal molecules 4431 tilts in the direction perpendicular to the drain electrode 4423. In FIG. 44B, it is oriented in the direction of 60 degrees clockwise when displaying white. Here, the optical axis 4443 of the λ / 4 plate was set in a direction almost perpendicular to the orientation direction of the liquid crystal molecules 4431 in white and at an angle of 45 degrees with the absorption axis 4442 of the polarizer. The analyzer's absorption axis 4441 is perpendicular to the polarizer's absorption axis 4442.
[0160]
Here, in a display such as an IPS type, the orientation direction of liquid crystal molecules in white display cannot be completely specified. In this case, the liquid crystal molecules rotate so that the orientation of the λ / 4 plate is orthogonal to the orientation considered to be oriented as much as possible, and the angle of λ / 4 and the absorption axis of the polarizer is 45 degrees. It was set to make.
[0161]
According to the present embodiment, in FIGS. 41A and 41B, the backlight 4101 supplies light. The cholesteric liquid crystal layer 4102 and the quarter wavelength plate 4103 are sandwiched between the backlight 4101 and the liquid crystal panel 4104. The alignment direction of the liquid crystal molecules of the liquid crystal panel 4104 and the optical axis of the quarter wave plate 4103 are orthogonal to each other.
[0162]
As shown in FIG. 39, the liquid crystal panel is vertically aligned when no voltage is applied to the liquid crystal panel, and tilts in two directions 3711 and 3712 that are 180 degrees different from each other when a voltage is applied. Further, it may be tilted to one position by applying a voltage.
[0163]
42, a scattering layer 4203 is formed between the quarter-wave plate 4202 and the liquid crystal panel 4104 (FIGS. 41A and 41B). The scattering layer 4203 has a haze value of 40 or more.
[0164]
44A and 44B, in the liquid crystal panel, the alignment of the liquid crystal molecules 4431 is horizontal alignment when a voltage is applied, and the alignment direction is perpendicular to the optical axis 4443 of the quarter-wave plate. In the liquid crystal panel, the alignment of the liquid crystal molecules may be horizontal when no voltage is applied, and the alignment direction may be perpendicular to the optical axis of the quarter-wave plate. The display mode of the liquid crystal panel is an in-plane switching mode.
[0165]
As described above, by using this embodiment, a bright display can be realized and a liquid crystal display with a wide viewing angle can be realized.
[0166]
(Sixth embodiment)
45A and 45B show examples of the electrode structure of an MVA liquid crystal panel. 45A shows the case of 4 domains, and FIG. 43B shows the case of 2 domains. The MVA type liquid crystal panel is provided with domain regulating means made of at least one of a pair of substrates, a protrusion, a depression, a slit provided in the electrodes 4510 and 4540, or a combination thereof. When nematic liquid crystal having negative dielectric anisotropy is used and no voltage is applied, liquid crystal molecules are aligned substantially perpendicular to the substrate. When a voltage is applied, the domain regulating means regulates the direction in which the liquid crystal molecules are inclined to be a plurality of directions in each pixel. A pair of polarizing elements are arranged on both sides of the liquid crystal panel so that the absorption axes 4501 and 4502 (absorption axes 4531 and 4532) are orthogonal to each other.
[0167]
In the case of fine slit electrodes 4510 and 4540 having a pitch of about 6 μm (line / space: 3 μm / 3 μm), liquid crystal molecules are inclined in a direction parallel to the slit when a voltage is applied.
[0168]
Therefore, as shown in FIG. 45A, when the slit electrode 4510 is formed so that the liquid crystal molecules 4521 to 4524 are inclined in four directions, the alignment of the four domains 4511 to 4514 is realized. As shown in FIG. 45B, when the slit electrode 4540 is formed so that the liquid crystal molecules 4551 and 4552 are inclined in two directions, the alignment of the two domains 4541 and 4542 is realized.
[0169]
Next, the relationship between the tilt direction of the liquid crystal molecules and the absorption axis direction of the polarizing element will be described with reference to FIGS. As shown in FIG. 46A, when the voltage is off, the liquid crystal molecules 4602 are aligned perpendicular to the substrate surface. FIG. 46A shows the relationship between the liquid crystal molecules 4602 at this time and the absorption axes 4601 and 4603 of the pair of polarizing elements. The light that has passed through one polarizing element passes through the liquid crystal without being affected by the birefringence of the liquid crystal molecules 4602 and is blocked by the other polarizing element, thereby obtaining a black display.
[0170]
As shown in FIGS. 46B and 46C, when the voltage is on, the liquid crystal molecules having negative dielectric anisotropy are inclined with respect to the substrate surface, and when a sufficiently large voltage is applied, the liquid crystal molecules 4612, 4622 is substantially parallel to the substrate surface. In order to realize an optimum white display, the direction in which the liquid crystal molecules are tilted is restricted with respect to the direction of the absorption axis.
[0171]
FIG. 46B shows the case where the liquid crystal molecules 4612 are tilted in the direction parallel or orthogonal to the absorption axis 4613 when the voltage is on. In this case, similarly to when the voltage is off, the light that has passed through one polarizing element passes through the liquid crystal without being affected by the birefringence of the liquid crystal molecules 4612 and is blocked by the other polarizing element. Therefore, a white display cannot be obtained.
[0172]
In order to obtain the optimum white display, the tilt direction of the liquid crystal molecules 4622 must be 45 degrees with respect to the absorption axes 4621 and 4623 as shown in FIG. In this case, the linearly polarized light that has passed through one polarizing element becomes elliptically polarized light due to the influence of the birefringence of the liquid crystal molecules 4622, and light that passes through the other polarizing element is generated, whereby white display is obtained.
[0173]
Therefore, as shown in FIG. 46D, in the MVA type liquid crystal panel, the four directions in which the liquid crystal molecules 4641 to 4644 should tilt when a voltage is applied are limited to the directions that form 45 degrees with respect to the absorption axes 4631 and 4632. It is done.
[0174]
In an MVA liquid crystal panel in which liquid crystal molecules tilt in different directions when a voltage is applied within one pixel, the liquid crystal molecules tilt only in four directions shown in FIG. 46D. desirable. However, in reality, there are liquid crystal molecules inclined in directions other than the four directions shown in FIG.
[0175]
An MVA type liquid crystal panel having electrodes 4710 of four domains 4711 to 4714 shown in FIG. 47 will be described as an example. Liquid crystal molecules 4721 to 4724 are inclined in four different directions by fine slit electrodes 4710 formed so as to form 45 degrees with respect to absorption axes 4701 and 4702 of the pair of polarizing elements. However, in the boundary region where each region is adjacent, the liquid crystal molecules 4725 to 4728 must be inclined in an orientation parallel or orthogonal to the absorption axes 4701 and 4702.
[0176]
In the region where the liquid crystal molecules 4725 to 4728 are inclined in the direction parallel or orthogonal to the absorption axes 4701 and 4702, light is not transmitted. Therefore, in the case of the electrode structure shown in FIG. 47, a black area is formed in a cross shape in white display, which is a major factor for reducing the transmittance.
[0177]
In the embodiment of the present invention, in the MVA liquid crystal panel, the direction of the domain restricting means periodically arranged at a fine pitch is 45 degrees with respect to the absorption axis of the polarizing element and the other directions. To include.
[0178]
As described above, in the MVA liquid crystal panel, when the liquid crystal molecules are tilted in an orientation other than 45 degrees with respect to the absorption axis of the polarizing element, the region does not transmit light, and thus the factor of decreasing the transmittance. It became. Means for solving this problem will be described below.
[0179]
The first means is to add a chiral agent to the liquid crystal material. By adding a chiral agent, liquid crystal molecules are tilted while twisting from one substrate to the other when a voltage is applied. This utilizes the same principle as a horizontally aligned liquid crystal panel generally called a TN mode. Therefore, it is desirable that the twist angle of the liquid crystal molecules is around 90 degrees.
[0180]
That is, when d is the cell gap of the liquid crystal panel and p is the helical pitch of the chiral agent, it is desirable that d / p = 1/4, and at least 1/8 ≦ d / p ≦ 3/8 must be satisfied. I must.
[0181]
48, as shown in FIG. 48, a pair of quarter-wave plates 4802 and 4804 are arranged on both sides of the liquid crystal panel 4803, and a pair of polarizing elements 4801 and 4805 are arranged on both sides thereof. The slow axes 4812 and 4814 of the quarter-wave plates 4802 and 4804 and the absorption axes 4811 and 4815 of the polarizing elements 4801 and 4805 adjacent thereto form 45 degrees, respectively. The quarter-wave plates 4802 and 4804 are arranged so that the slow axes 4812 and 4814 are orthogonal to each other, and the absorption axes 4811 and 4815 of the polarizing elements 4801 and 4805 are orthogonal to each other.
[0182]
The light that has passed through the polarizing element becomes linearly polarized light, and further becomes circularly polarized light by passing through the quarter wavelength plate. At this time, the transmitted light intensity does not depend on the tilt direction of the liquid crystal molecules, but is determined only by the retardation of the liquid crystal cell.
[0183]
49A to 49C show examples of patterns of domain regulating means (ITO pixel electrodes) arranged periodically. As shown in FIG. 49A, by arranging pixel electrodes 4901 as domain regulating means in a substantially radial manner, the tilt direction of the liquid crystal molecules can be continuously changed from approximately 0 to 360 degrees. .
[0184]
Similarly, as shown in FIG. 49B, the pattern of the pixel electrode 4902 in which the tilt directions of the liquid crystal molecules are eight, and as shown in FIG. 49C, the concentric pixel electrode 4903 is formed. Various variations such as patterns are possible. The pixel electrodes 4901 to 4903 in FIGS. 49A to 49C are each connected to one pixel electrode.
[0185]
As described above, the direction of the domain regulating means periodically arranged at a fine pitch includes a direction forming 45 degrees with respect to the absorption axis of the polarizing element and other directions, and adding a chiral agent In combination with a quarter-wave plate, a wide viewing angle and high brightness can be realized simultaneously.
[0186]
This embodiment will be described more specifically. A solid electrode is formed on the entire surface of the display region on one of the pair of substrates constituting the liquid crystal panel. A pixel electrode is formed on the other substrate. As shown in FIG. 49A, the pixel electrode is formed of a fine slit electrode 4901 having a radial pattern. Further, a color filter, a gate bus line, a data bus line, a TFT element, and the like are formed on the substrate.
[0187]
A vertical alignment film is formed on both substrates. Both substrates are bonded via a spacer, and a nematic liquid crystal having negative dielectric anisotropy added with a chiral agent so as to satisfy d / p = 1/4 is sealed to produce a liquid crystal panel. Polarizing elements are arranged on both sides of the liquid crystal panel so that the absorption axes are orthogonal to each other.
[0188]
Another configuration example will be described. A solid electrode is formed on the entire surface of the display region on one of the pair of substrates constituting the liquid crystal panel. A pixel electrode is formed on the other substrate. As shown in FIG. 49A, the pixel electrode is formed of a fine slit electrode 4901 having a radial pattern. Further, a color filter, a gate bus line, a data bus line, a TFT element, and the like are formed on the substrate.
[0189]
A vertical alignment film is formed on both substrates. Both substrates are bonded together via a spacer, and a nematic liquid crystal having negative dielectric anisotropy is sealed to manufacture a liquid crystal panel.
[0190]
Polarizing elements are arranged on both sides of the liquid crystal panel so that the absorption axes are orthogonal to each other. One quarter wavelength plate is disposed between the liquid crystal panel and the polarizing elements on both sides, and the slow axis of the quarter wavelength plate and the absorption axis of the adjacent polarizing element form 45 degrees, and the quarter wavelength. The plates are arranged so that their slow axes are orthogonal to each other.
[0191]
According to this embodiment, as shown in FIG. 48, the liquid crystal panel 4803 has liquid crystal sealed between a pair of substrates. The pair of polarizing elements 4801 and 4805 are arranged on both sides of the liquid crystal panel 4803 so that the absorption axes are orthogonal to each other. Domain regulating means is provided on at least one surface of the pair of substrates constituting the liquid crystal panel 4803. The domain regulating means regulates the orientation of the liquid crystal molecules in the liquid crystal panel, including a periodic pattern of any one of protrusions such as banks, depressions, slits provided in the electrodes (FIG. 47), or a combination thereof.
[0192]
As shown in FIG. 47, the orientation direction of the liquid crystal molecules 4721 to 4728 by the domain regulating means includes four directions forming 45 degrees with respect to the absorption axes 4701 and 4702 of the polarizing element and other directions. In the liquid crystal panel, when no voltage is applied, the liquid crystal molecules are aligned substantially perpendicular to the substrate, and when a voltage is applied, the direction in which the liquid crystal molecules are slanted by the domain regulating means becomes a plurality of directions in each pixel. Regulated by
[0193]
As shown in FIGS. 49A to 49C, the liquid crystal panel includes a region where the alignment direction of the liquid crystal molecules by the domain regulating means continuously changes, and a region where the liquid crystal panel continuously changes from 0 degrees to 360 degrees. But you can. In FIG. 49 (A), the domain regulating means includes a radially arranged region, and the width of the domain regulating means becomes wider from the center of the radial pattern to the outside. In FIG. 49C, the domain regulating means includes a region arranged concentrically.
[0194]
In the liquid crystal panel, a chiral agent is added to the liquid crystal material. When the cell gap of the liquid crystal panel is d and the helical pitch of the chiral agent is p, 1/8 ≦ d / p ≦ 3/8 is satisfied.
[0195]
As shown in FIG. 48, the pair of quarter-wave plates 4802 and 4804 are provided so as to sandwich the liquid crystal panel 4803 between the pair of polarizing elements 4801 and 4805. The slow axis of the pair of quarter wave plates 4802 and 4804 and the absorption axis of the pair of polarizing elements 4801 and 4805 adjacent to each other form 45 degrees, and the slow phase of the pair of quarter wave plates 4802 and 4804 The axes are orthogonal to each other.
[0196]
As described above, according to the present embodiment, a liquid crystal display device with a wide viewing angle and high brightness can be realized.
[0197]
(Seventh embodiment)
Examples of the MVA type orientation control technology include the following.
(1) Orientation control by bank or slit
50A and 50B show the orientation control by the bank. A liquid crystal layer 5002 is provided between the counter substrate 5001 and the TFT substrate 5003. The counter substrate 5001 is provided with a transparent electrode 5012 and a bank 5011. The TFT substrate 5003 is provided with a transparent electrode 5016 and a bank 5015. As shown in FIG. 50A, when no voltage is applied, the liquid crystal molecules 5013 near the banks 5011 and 5015 are inclined according to the shapes of the banks 5011 and 5015. Liquid crystal molecules 5014 away from the banks 5011 and 5015 are vertically aligned. As shown in FIG. 50B, when voltage is applied, the electric field 5021 is formed in accordance with the shapes of the banks 5011 and 5015. A force for aligning the liquid crystal molecules 5022 in a direction perpendicular to the electric field 5021 acts. As described above, the alignment of the liquid crystal molecules can be controlled by the banks 5011 and 5015.
[0198]
FIGS. 50C and 50D show alignment control by the electrode slit. A liquid crystal layer 5032 is provided between the counter substrate 5031 and the TFT substrate 5033. The counter substrate 5031 is provided with a transparent electrode 5041. The TFT substrate 5033 is provided with a transparent electrode 5042 having a slit. As shown in FIG. 50C, when no voltage is applied, the liquid crystal molecules 5043 are aligned vertically to the substrate. As shown in FIG. 50D, when voltage is applied, an oblique electric field 5051 is generated by the slit of the transparent electrode 5042. A force to align the liquid crystal molecules 5052 in a direction perpendicular to the electric field 5051 is applied. As described above, the alignment of the liquid crystal molecules can be controlled by the slit-shaped electrode 5042. The operation of the bank and the liquid crystal in the vicinity thereof is the same as that shown in FIG.
[0199]
(2) Orientation control by auxiliary bank and auxiliary slit
FIG. 51A shows the orientation control by the auxiliary bank. The pixel electrode 5101 is provided on the TFT substrate, and the bank 5102 is provided on the counter substrate. Further, an auxiliary bank 5103 is provided on the counter substrate corresponding to the edge portion of the pixel electrode 5101. The liquid crystal molecules 5104 can align the alignment direction of the liquid crystal even between the bank 5102 and the auxiliary bank 5103. Without the auxiliary bank 5103, as shown in FIG. 51C, the alignment of the liquid crystal 5122 controlled by the bank 5102 and the alignment of the liquid crystal 5121 controlled by the electric field at the edge portion of the pixel electrode 5101 are in competition. .
[0200]
FIG. 51B shows the alignment control by the auxiliary slit. The pixel electrode 5113 is provided with a slit 5111. Further, an auxiliary slit 5112 is provided in the vicinity of the edge portion of the pixel electrode 5113. Competition between the alignment by the edge portion of the pixel electrode 5113 and the alignment by the slit 5111 can be prevented, and the alignment direction of the liquid crystal molecules can be aligned.
[0201]
(3) Orientation control by fine pattern (bank, slit)
FIG. 52A shows the alignment control by the fine slit. The pixel electrode 5201 has a fine slit. The electric field 5202 is formed according to the shape of the fine slit. The liquid crystal molecules 5203 are aligned according to the electric field 5202. As shown in FIG. 52B, a slit 5212 is provided between the pixel electrodes 5211 and 5213, and a bank 5214 is further provided. The alignment direction of the liquid crystal molecules 5221 when a voltage is applied is controlled by an electric field generated in the vicinity of the slit 5212 of the pixel electrode 5213. The alignment of the liquid crystal molecules 5223 is controlled by a bank 5214. When the minute slits in FIG. 52A are formed in the pixel electrode 5213, the orientation of the liquid crystal molecules 5222 between the liquid crystal molecules 5221 and 5223 can also be controlled.
[0202]
(4) Orientation control by paddy pattern
FIG. 53 shows orientation control by a square pattern (cross pattern). The pixel electrode 5303 is provided on the TFT substrate. Cross-shaped banks 5301 and 5302 are provided on the counter substrate. The banks 5301 and 5302 form four regions, and the liquid crystal molecules 5311 to 5314 in each region can be aligned in different directions.
[0203]
Each of the above-mentioned orientation controls (1) to (4) has characteristics, and it is desirable to use them properly depending on the application. However, for example, in the control according to (1), it is necessary to arrange a large number of banks and slits, and in FIG. 14, the layout is such that the slits are located immediately inside the pixel edge like the upper left and lower left corners of the pixel electrode 1404. There is a case. Since the pixel edge is equivalent to the slit, the control of the slit is adjacently influenced at the upper left and lower left corners. An unstable domain occurred in the pixel corner, and the luminance was lowered.
[0204]
It is difficult to completely control the orientation of the entire area within the pixel by only one type of control (1) to (4). Especially this problem is
a) Higher brightness (increased transmittance)
b) High definition
c) Fast response
When doing, it becomes a serious problem.
[0205]
Rather than using the control means (1) to (4) individually, it is more effective to combine the control means suitable for the essential pixel locations in combination.
FIG. 54 shows a first configuration example. Pixel electrodes are provided corresponding to the data lines 5401 and the gate lines 5402. First, the fine slits 5416 are laid out in the pixel corner portion to facilitate the layout in the corner portion. In FIG. 54, it is only necessary to lay out two straight banks 5411 and 5417 in the pixel and extend the fine slit 5416 from there toward the pixel corner. Not only is the layout simple, but unstable domains are not formed, and the transmittance is increased. In addition, the orientation is controlled by a slit 5412, a fine slit 5415, an auxiliary slit 5414, and an auxiliary bank 5413. The bank and the auxiliary bank are provided on the counter substrate, and the data line, the gate line, the pixel electrode, and the electrode slit are provided on the TFT substrate.
[0206]
According to this configuration, the transmittance is improved by 10 to 20% compared to the single technique (1). There are locations in the pixel where it is better to change the orientation direction of the liquid crystal within a range of 90 degrees or less, and locations where it is better to change the orientation direction within a range of 90 to 180 degrees. For example, the control by the bank (1) is a control means suitable for changing the orientation direction of 180 degrees, but ideal control is difficult even if it is applied to a place where 90-degree deformation is required.
[0207]
(1) is 180 degrees
(2), (4) is 90 degrees
(3) can correspond to either by the angle to attach.
[0208]
FIG. 54 will be described in more detail. A fine slit 5416 was extended to the upper right and lower right corner of the pixel to match the corner shape. (3) A fine slit 5415 is provided in a direction orthogonal to the main slit 5412 to enhance controllability. Further, the fine slit 5415 at the pixel edge portion is partially deepened to (2) the auxiliary fine slit 5414 to suppress the occurrence of abnormal domains. Of course, (1) Banks 5411 and 5417 which are the basis of MVA are also provided, and the techniques (1) to (3) are laid out in the right place. (1) The transmittance was improved by about 1.15 times compared to the control using only the bank and slit, which is the basis of MVA.
[0209]
FIG. 55 shows a second configuration example. A TFT substrate is provided with a data line 5501, a gate line 5502, a pixel electrode 5512, and an auxiliary fine electrode slit 5513. A bank 5511 is provided on the counter substrate. In the second configuration example, the technique (3) is more actively used than in the first configuration example, and the fine slit 5513 is matched with the shape of the location where the orientation direction of the pixel corner and the pixel center is deformed by 90 °. Provided. In this case, the number of domains is only four, and the transmittance loss at the alignment division part can be minimized. The transmittance improved by 1.09 times more than the first configuration example.
[0210]
FIG. 56 shows a third configuration example. The TFT substrate is provided with a data line 5501, a gate line 5502, a pixel electrode 5612, and an auxiliary fine electrode slit 5613. A bank 5611 is provided on the counter substrate. Similarly to the second configuration example, the third configuration example has a configuration with four domains. Basically, it is similar to the second configuration example, but the main slit 5614 is obliquely provided in the center of the pixel and the point that the bank 5611 is arranged in a T shape (control of (2) and (4)). Different points. The third configuration example includes all the control methods (1) to (4). The transmittance was improved 1.12 times compared to the first configuration example.
[0211]
FIG. 57 shows a fourth configuration example. A TFT substrate is provided with a data line 5501, a gate line 5502, a pixel electrode 5712, and an auxiliary fine electrode slit 5713. A bank 5711 is provided on the counter substrate. Although it is similar to the third configuration example, the way of attaching the bank 5711 is different. The transmittance was improved by about 10% compared to the first configuration example.
[0212]
58 to 60 show a fifth configuration example. 58, a data line 5501, a gate line 5502, a pixel electrode 5811, and a contact region 5812 are provided on the TFT substrate. In FIG. 59, a data line 5501, a gate line 5502, a pixel electrode 5911, and a contact region 5912 are provided on the TFT substrate, and a bank 5913 is provided on the counter substrate. In FIG. 60, a data line 5501, a gate line 5502, a pixel electrode 6011, and a contact region 6012 are provided on the TFT substrate, and a bank 6013 is provided on the counter substrate. In the fifth configuration example, the fine electrodes are connected in a form of being connected by a cross pattern at the center of the pixel. Each has a layout in which the controls (2) to (4) are combined. The transmittance was improved by about 20% compared to the first configuration example.
[0213]
61 and 62 show a sixth configuration example. In FIG. 61, a data line 5501, a gate line 5502, and a pixel electrode 6111 are provided on the TFT substrate, and a bank 6112 is provided on the counter substrate. In FIG. 62, a data line 5501, a gate line 5502, and a pixel electrode 6211 are provided on the TFT substrate, and a bank 6212 is provided on the counter substrate. The sixth configuration example is similar to the fifth configuration example, but the connection method of the fine electrodes is different, and the pixels are connected by a linear pattern at the center of the pixel. The transmittance was the same as in the fifth configuration example, which was improved by about 20% compared to the first configuration example. The second to sixth configuration examples are all configured with four domains, and are particularly advantageous when applied with high definition.
[0214]
63 to 66 show a seventh configuration example. In FIG. 63, a data line 5501, a gate line 5502, and a pixel electrode 6311 are provided on the TFT substrate, and a bank 6312 is provided on the counter substrate. In FIG. 64, a data line 5501, a gate line 5502, and a pixel electrode 6411 are provided on the TFT substrate, and a bank 6412 is provided on the counter substrate. In FIG. 65, a data line 5501, a gate line 5502, and a pixel electrode 6511 are provided on the TFT substrate. In FIG. 66, a data line 5501, a gate line 5502, and a pixel electrode 6611 are provided on the TFT substrate, and a bank 6612 is provided on the counter substrate. In all the seventh configuration examples, the number of divided domains is six. These are suitable when the pixels are relatively large (it does not mean that the second to sixth configuration examples cannot cope with large pixels). This is because if the number of divisions is reduced with a large pixel, the area of one divided region increases, and the region that must be covered by one control element increases. Even in the seventh configuration example, the transmittance was improved by about 10% compared to the first configuration example.
[0215]
67 and 68 show an eighth configuration example. In FIG. 67, a data line 5501, a gate line 5502, a pixel electrode 6711, and a fine slit 6712 are provided on the TFT substrate, and a bank 6713 is provided on the counter substrate. In FIG. 68, a data line 5501, a gate line 5502, a pixel electrode 6811, and a bank 6813 are provided on the TFT substrate, and a bank 6812 is provided on the counter substrate. The eighth configuration example is a six-domain configuration that is an improved version of the first configuration example. The transmittance is higher because the bank area in the pixel is smaller than in the first configuration example. Compared to the first configuration example, it is improved by about 0.5%.
[0216]
The ninth configuration example incorporates a slightly different idea from the other configuration examples. In the ninth configuration example, FIG. 67 shows only one pixel, but the adjacent pixel is laid out by inverting the pattern left and right (neighboring pixels do not necessarily have to be reversed but are adjacent pixels). It only has to be reversed). A four-way domain is obtained with one set of two pixels. The transmittance was improved by about 10% compared to the first configuration example.
[0217]
FIG. 69 shows a tenth configuration example. The bank 6901 is provided on the counter substrate (upper substrate), and the bank 6902 is provided on the TFT substrate (lower substrate). The bank pattern is exchanged between the upper and lower substrates in a region where the orientation direction changes by 90 °. By doing so, the liquid crystal orientation can be changed without difficulty, and a stable alignment can be obtained. As a result of applying this pattern to the center of the pixel in the first configuration example, the transmittance was improved by about 0.5%.
[0218]
The above configuration example is only an example, and basically the above-described transmittance improvement effect can be expected by combining the controls (1) to (4) in the right place (of course, if wrong combinations are made). The effect drops). Needless to say, it is possible to further stabilize the alignment and increase the response speed by a method of polymerizing the monomer mixed in the liquid crystal to polymerize it. Furthermore, the transmittance can be further increased in combination with the λ / 4 plate.
[0219]
According to this embodiment, as shown in FIG. 50A, the two substrates 5001 and 5003 are subjected to vertical alignment processing on the substrate surfaces, and the liquid crystal layer 5002 is vertically aligned without application of voltage. As shown in FIG. 50B, the liquid crystal layer 5002 is a negative liquid crystal layer which is sandwiched between substrates and in which liquid crystal molecules are directed in a vertical direction with respect to an electric field 5021 by voltage application. The domain regulating means regulates the direction in which the orientation of the liquid crystal is oblique when a voltage is applied to the direction of a plurality of liquid crystal domains in each pixel, and includes first and second domain regulating means. The first restricting means is partially provided in the pixel or its peripheral region, and the alignment direction of the liquid crystal is varied in the range of 90 to 180 degrees across the center of the partially provided domain restricting means. The second domain regulating means varies the alignment direction of the liquid crystal within a range of 0 to 90 degrees. The first and second domain regulating means preferably regulate the liquid crystal domain so that the number of domains formed in the pixel is 4 to 12.
[0220]
The first domain regulating means includes a dielectric protrusion (bank) 5214 (FIG. 52B) extending in a direction different from 45 to 90 degrees from the direction of the liquid crystal domain, and extending in a direction different from 45 to 90 degrees from the direction of the liquid crystal domain. Electrode slits 5213 and 5212 (FIG. 52B), electrode slits 5201 (FIG. 52A) elongated in the direction of the liquid crystal domain and periodically repeated in a direction different by 45 to 90 degrees from the direction of the liquid crystal domain. The dielectric protrusion is elongated in the direction of the domain and periodically repeated in a direction different from 45 to 90 degrees from the direction of the liquid crystal domain, or a combination of a plurality of these.
[0221]
The second domain regulating means includes dielectric protrusions (banks) 5301 and 5302 (FIG. 53) extending in a direction different from 0 to 45 degrees from the liquid crystal domain direction, or electrodes extending in a direction different from the liquid crystal domain direction by 45 degrees. It is a slit.
[0222]
The above-described embodiments are merely examples of implementation in carrying out the present invention, and the technical scope of the present invention should not be construed in a limited manner. That is, the present invention can be implemented in various forms without departing from the technical idea or the main features thereof.
[0223]
The embodiment of the present invention can be applied in various ways as follows, for example.
(Appendix 1) a pair of substrates;
The liquid crystal molecules are sandwiched between the pair of substrates so that the liquid crystal molecules are vertically aligned with respect to the substrate when no voltage is applied between the substrates, and the liquid crystal molecules are substantially parallel to the substrate by applying a voltage between the substrates. A liquid crystal display device having a liquid crystal layer falling in a plurality of directions,
The liquid crystal layer defines an angle counterclockwise when the right direction of the screen is set to 0 degrees when the voltage is applied, and a ratio of a region in which the liquid crystal molecules are tilted in the 0 to 180 degree azimuth and the 180 to 360 degree azimuth. Liquid crystal display devices in which the ratio of the region where the liquid crystal molecules are inclined is different.
(Appendix 2) The liquid crystal layer defines an angle counterclockwise when the screen right direction is set to 0 degrees when the voltage is applied, and a ratio of a region in which the liquid crystal molecules are tilted to 45 degrees and 135 degrees, Item 2. The liquid crystal display device according to appendix 1, wherein the ratio of the region where the liquid crystal molecules are inclined in the directions of 225 degrees and 315 degrees is different.
(Supplementary note 3) The liquid crystal display device according to supplementary note 2, wherein the liquid crystal layer has a ratio of a region where the liquid crystal molecules are inclined in the 45-degree and 135-degree orientations of 40% or less.
(Supplementary Note 4) Further, the pixel electrode is provided on at least one of the pair of substrates, and has a squirrel-like pixel electrode having a width of 10 μm or less and a gap of 10 μm or less,
The liquid crystal display device according to appendix 2, wherein the liquid crystal layer has liquid crystal molecules tilted in four directions as the orientation direction of liquid crystal molecules is regulated by the pixel electrode.
(Additional remark 5) Furthermore, it has a thin-film transistor containing a gate, a source, and a drain,
The liquid crystal display device according to appendix 1, wherein the pixel electrode has a contact region for connecting to a drain of the thin film transistor, and a slit is provided between at least a part of the plurality of soots and the contact region.
(Appendix 6) First and second substrates;
A sawtooth pixel electrode provided on the first substrate and having a width of 10 μm or less and a gap of 10 μm or less;
A liquid crystal display device having a liquid crystal layer sandwiched between the first and second substrates, the orientation direction of which is regulated by the pixel electrode, and a direction in which liquid crystal molecules are inclined in two vertical directions of the screen; ,
The pixel electrode is a liquid crystal display device in which a gap between a self sac-like pixel electrode and a gap between adjacent pixel electrodes are the same.
(Appendix 7) Further, a thin film transistor connected to the pixel electrode in the first substrate;
The liquid crystal display device according to appendix 6, further comprising a color filter layer formed on the first substrate.
(Appendix 8) First and second substrates;
A liquid crystal layer sandwiched between the first and second substrates and in which liquid crystal molecules are vertically aligned with respect to the first and second substrates in a state where no voltage is applied between the first and second substrates; ,
A thin film transistor provided on the first substrate and including a gate, a source, and a drain;
A gate line connected to the gate of the thin film transistor;
A data line connected to a source of the thin film transistor;
Comb-shaped or slit-shaped pixel electrode connected to the drain of the thin film transistor, the direction of the comb teeth extending toward the gate line in the vicinity of the gate line, and the data line in the vicinity of the data line And a pixel electrode extending toward the surface.
(Additional remark 9) Furthermore, it has the electrode line for auxiliary capacity formation extended in the horizontal direction of the center of a pixel,
9. The liquid crystal display device according to appendix 8, wherein the pixel electrode is divided into upper and lower parts with the auxiliary capacitor forming electrode line as a boundary, and overlaps the auxiliary capacitor forming electrode line in the vicinity of the auxiliary capacitor forming electrode line.
(Additional remark 10) The said pixel electrode is vertically formed in the center of the pixel in the shape of a backbone, and is connected to the comb-like electrode toward the gate line and the comb-like electrode toward the data line. Item 9. The liquid crystal display device according to appendix 8, wherein the electrode portion extends in four directions from the spine-shaped electrode and has a Y-shaped arm shape.
(Supplementary note 11) The liquid crystal display device according to supplementary note 9, wherein the pixel electrode has a comb tooth direction extending toward the auxiliary capacitance forming electrode line in the vicinity of the auxiliary capacitance forming electrode line.
(Supplementary note 12) The liquid crystal display according to supplementary note 8, wherein the pixel electrode extends in a direction inclined toward the data line in the vicinity of the data line as a direction in which the comb-like electrode extends toward the gate line. apparatus.
(Supplementary note 13) The liquid crystal display according to supplementary note 8, wherein the pixel electrode extends in a direction inclined toward the gate line in the vicinity of the gate line as a direction in which a comb-like electrode extending toward the data line extends. apparatus.
(Supplementary note 14) The liquid crystal display device according to supplementary note 8, wherein the pixel electrode has a comb-teeth shape and a tip portion of the tooth is narrower or narrower.
(Supplementary Note 15) The pixel electrode includes an electrode provided to transmit a voltage from the drain of the thin film transistor across the auxiliary capacitance forming electrode line, and the auxiliary capacitance is formed in the vicinity of the auxiliary capacitance forming electrode line. Item 9. The liquid crystal display device according to appendix 8, which extends in the same direction so as to overlap the forming electrode line.
(Supplementary note 16) The liquid crystal display device according to supplementary note 8, further comprising a pair of orthogonal quarter-wave plates sandwiching the first and second substrates sandwiching the liquid crystal layer.
(Supplementary Note 17) A pair of polarizing layers whose absorption axes are orthogonal to each other;
A half-wave plate having a half-wave phase difference sandwiched between the pair of polarizing layers;
A liquid crystal display device having a liquid crystal layer sandwiched between the pair of polarizing layers and capable of vertically aligning liquid crystal molecules,
The half-wave plate is
A film having a phase difference of ½ wavelength is laminated, and the phase difference in the direction perpendicular to the film surface ((nx + ny) / 2−nz) × d (the refractive index in the direction perpendicular to the film surface is nz, the film The refractive index in the direction parallel to the optical axis of the film is nx, the refractive index in the in-plane direction perpendicular to the optical axis of the film is ny, and the film thickness of the film is d) is 0 or ± 20 nm or less. The optical axis is parallel or perpendicular to the absorption axis of the adjacent polarizing layer;
Or, two films having a phase difference of ½ wavelength are laminated, the refractive index in the direction perpendicular to the film surface is nz, the refractive index in the direction parallel to the optical axis of the film is nx, and the light of the film When the refractive index in the in-plane direction of the film perpendicular to the axis is ny, the values of (nx−nz) / (nx−ny) of the two films are 0.5 or less and 0.5 or more, respectively. A liquid crystal display device in which the optical axis of the film is parallel and parallel or perpendicular to the absorption axis of the polarizing layer adjacent thereto.
(Supplementary Note 18) The half-wave plate has a retardation ((nx + ny) / 2-nz) × d of ± 10 nm or less, or (nx-nz) / (nx-ny) of the two films. 18. The liquid crystal display device according to appendix 17, wherein the sum of the values of is approximately 1.
(Supplementary Note 19) Further, Δn × d (Δn is n // − n⊥, where n // is a refractive index in the longitudinal direction of the liquid crystal molecules, and n⊥ is a liquid crystal molecule. The film having a negative phase difference of the same size as that of the refractive index in the direction perpendicular to the longitudinal direction of the liquid crystal and d being the thickness is provided close to the liquid crystal layer. Liquid crystal display device.
(Additional remark 20) Furthermore, it has a pair of 1/4 wavelength plates whose negative phase difference is 0 or ± 10 nm or less so as to sandwich the liquid crystal layer and the film,
20. The liquid crystal display device according to appendix 19, wherein optical axes of the pair of quarter-wave plates are orthogonal to each other and form an angle of 45 degrees with an absorption axis of the pair of polarizing layers.
(Supplementary note 21) The liquid crystal display according to supplementary note 20, wherein the direction of the absorption axis of the polarizing layer on the light incident side is set to 0 degree, 45 degrees, 90 degrees, or 135 degrees with the right side of the screen being 0 degrees apparatus.
(Supplementary Note 22) The relationship between the optical axis of the light incident side polarizing layer, the light emitting side polarizing layer, the ¼ wavelength plate, and the ½ wavelength plate is the maximum while maintaining the above relationship. Item 20. The liquid crystal display device according to appendix 20, wherein the direction of the absorption axis of the polarizing layer is adjusted so that the azimuth becomes the vertical and horizontal azimuth.
(Supplementary Note 23) First and second polarizing plates;
A liquid crystal layer sandwiched between the first and second polarizing plates and capable of vertically aligning liquid crystal molecules;
A retardation film having a phase difference in a plane sandwiched between the first and second polarizing plates, provided such that an optical axis thereof is perpendicular to an absorption axis of a neighboring polarizing plate, and a refractive index thereof is a retardation film having a relationship of nx>nz> = ny (nx is a refractive index in the optical axis direction, ny is a refractive index in an in-plane direction perpendicular to nx, and nz is a refractive index in a direction perpendicular to the surface). Liquid crystal display device.
(Supplementary note 24) The liquid crystal display device according to supplementary note 23, wherein the first polarizing plate is provided with a protective film having a thickness of 100 microns or more on a surface thereof.
(Supplementary note 25) The liquid crystal display device according to supplementary note 23, wherein the retardation film has an in-plane retardation (nx−ny) × d (d is a thickness) of 40 nm to 140 nm (preferably 40 nm to 130 nm).
(Supplementary Note 26) The liquid crystal layer has a phase difference RLC = (n // − n∥) × d (n // is a refractive index in the longitudinal direction of the liquid crystal molecules when the liquid crystal molecules are vertically aligned. The refractive index in the direction perpendicular to the longitudinal direction of the liquid crystal molecules, d is the thickness)
When the negative retardation of the protective film of the first polarizing plate, the negative retardation of the retardation film, and other layers having a negative retardation are applied, the sum of the negative retardation is defined as R negatotal when doing,
20 nm <RLC-R negatototal <150 nm
24. The liquid crystal display device according to appendix 23, having the relationship:
(Supplementary note 27) first and second polarizing plates;
A liquid crystal display device having a liquid crystal layer sandwiched between the first and second polarizing plates and capable of vertically aligning liquid crystal molecules,
The first polarizing plate includes a protective film having an in-plane retardation and a polarizing layer, and is provided so that an optical axis of the protective film is perpendicular or parallel to an absorption axis of the polarizing layer .
(Supplementary Note 28) In-plane retardation (nx−ny) × d (nx is the refractive index in the optical axis direction, ny is the refractive index in the in-plane direction perpendicular to nx, and d is the thickness) of the protective film is 40 nm or more. Appendix 27, wherein 140 nm or less (preferably 40 nm or more and 130 nm or less), and when the protective film is two sheets, the sum of the in-plane retardation of the two sheets is set to 40 nm or more and 140 nm or less (preferably 40 nm or more and 130 nm or less) Liquid crystal display device.
(Supplementary Note 29) The liquid crystal layer has a phase difference RLC = (n // − n⊥) × d (n // is a refractive index in the longitudinal direction of the liquid crystal molecules when the liquid crystal molecules are vertically aligned. The refractive index in the direction perpendicular to the longitudinal direction of the liquid crystal molecules, d is the thickness)
When the negative phase difference of the protective film and other layers having a negative phase difference are applied, the sum of the negative phase differences is set as R negatototal.
20 nm <RLC-R negatototal <150 nm
28. The liquid crystal display device according to appendix 27, wherein
(Supplementary Note 30) A cholesteric liquid crystal layer;
A quarter wave plate,
A backlight for supplying light;
A liquid crystal display device having a liquid crystal panel in which liquid crystal molecules can be aligned,
The cholesteric liquid crystal layer and the quarter wavelength plate are sandwiched between the backlight and the liquid crystal panel, and the alignment direction of the liquid crystal molecules of the liquid crystal panel and the optical axis of the quarter wavelength plate are orthogonal to each other. Liquid crystal display device.
(Supplementary note 31) The liquid crystal display device according to supplementary note 30, wherein the liquid crystal panel has a vertical orientation in which liquid crystal molecules are not applied with a voltage and is inclined to one position when a voltage is applied.
(Supplementary note 32) The liquid crystal display device according to supplementary note 30, wherein the liquid crystal panel is vertically aligned in a state where no voltage is applied, and is inclined in two directions different from each other by 180 degrees when a voltage is applied.
(Supplementary note 33) The liquid crystal display device according to supplementary note 30, wherein a scattering layer is formed between the quarter-wave plate and the liquid crystal panel.
(Supplementary note 34) The liquid crystal display according to supplementary note 30, wherein the liquid crystal panel has a liquid crystal molecule in a horizontal orientation when no voltage is applied, and the orientation direction is perpendicular to the optical axis of the quarter-wave plate. apparatus.
(Supplementary note 35) The liquid crystal display device according to supplementary note 30, wherein the liquid crystal panel has a liquid crystal molecule in a horizontal orientation when a voltage is applied, and the orientation direction is perpendicular to the optical axis of the quarter-wave plate. .
(Appendix 36) A liquid crystal panel in which liquid crystal is sealed between a pair of substrates;
A pair of polarizing elements disposed on both sides of the liquid crystal panel so that the absorption axes are orthogonal to each other;
Alignment of liquid crystal molecules in the liquid crystal panel, including at least one surface of a pair of substrates constituting the liquid crystal panel, a periodic pattern of any one of protrusions, depressions, slits provided in electrodes, or a combination thereof A liquid crystal display device having a domain regulating means for regulating
The orientation direction of the liquid crystal molecules by the periodically arranged domain regulating means includes a direction forming 45 degrees with respect to the absorption axis of the polarizing element and other directions, and when no voltage is applied, the liquid crystal molecules are A liquid crystal display device that is oriented substantially perpendicular to the liquid crystal and is regulated such that the direction in which the liquid crystal molecules are inclined becomes a plurality of directions in each pixel when a voltage is applied.
(Supplementary note 37) The supplementary note 36, wherein the orientation direction of the liquid crystal molecules by the periodically arranged domain regulating means includes four directions forming 45 degrees with respect to the absorption axis of the polarizing element and other directions. Liquid crystal display device.
(Supplementary note 38) The liquid crystal display device according to supplementary note 36, wherein the liquid crystal panel includes a region in which an orientation direction of liquid crystal molecules is continuously changed by the periodically arranged domain regulating means.
(Supplementary note 39) The liquid crystal display device according to supplementary note 36, wherein the periodically arranged domain regulating means includes a radially arranged region.
(Supplementary note 40) The liquid crystal display device according to supplementary note 36, wherein the periodically arranged domain regulating means includes regions arranged concentrically.
(Supplementary note 41) The liquid crystal display device according to supplementary note 36, wherein the liquid crystal panel has a chiral agent added to a liquid crystal material.
(Supplementary note 42) The liquid crystal display device according to supplementary note 36, further comprising a pair of quarter-wave plates provided so as to sandwich the liquid crystal panel between the pair of polarizing elements.
(Supplementary note 43) Two substrates having a substrate surface subjected to vertical alignment treatment;
A negative liquid crystal sandwiched between the substrates;
Domain restricting means for restricting the liquid crystal domains to be oriented in a plurality of liquid crystal domains in each pixel, the liquid crystal being partially provided in a pixel or a peripheral region thereof, and the liquid crystal sandwiching a center of the partially provided domain restricting means First domain regulating means for varying the orientation direction of the liquid crystal in the range of 90 to 180 degrees, and domain regulating means including second domain regulating means for varying the orientation direction of the liquid crystal in the range of 0 to 90 degrees. A liquid crystal display device.
(Supplementary note 44) The liquid crystal display device according to supplementary note 43, wherein the first domain regulating means is a dielectric protrusion extending in a direction orthogonal to a direction of the liquid crystal domain.
(Supplementary note 45) The liquid crystal display device according to supplementary note 43, wherein the first domain regulating means is an electrode slit extending in a direction orthogonal to a direction of the liquid crystal domain.
(Supplementary note 46) The liquid crystal display device according to supplementary note 43, wherein the first domain regulating means is a dielectric protrusion that is elongated in a direction of the liquid crystal domain and periodically repeated in a direction orthogonal to the direction of the liquid crystal domain.
(Supplementary note 47) The liquid crystal display device according to supplementary note 43, wherein the first domain regulating means is an electrode slit elongated in a direction of the liquid crystal domain and periodically repeated in a direction orthogonal to the direction of the liquid crystal domain.
(Supplementary Note 48) The first domain regulating means includes dielectric protrusions extending in a direction different from 45 to 90 degrees from the liquid crystal domain direction, electrode slits extending in a direction different from 45 to 90 degrees from the liquid crystal domain direction, Dielectric protrusions that are elongated in the direction of the liquid crystal domain and periodically repeated in a direction different from 45 to 90 degrees from the direction of the liquid crystal domain, and elongated in the direction of the liquid crystal domain and differ from the direction of the liquid crystal domain by 45 to 90 degrees. 44. The liquid crystal display device according to appendix 43, comprising a plurality of combinations of electrode slits periodically repeated in the direction.
(Supplementary note 49) The liquid crystal display device according to supplementary note 43, wherein the second domain regulating means is a dielectric protrusion extending in a direction different by 0 to 45 degrees from a direction of the liquid crystal domain.
(Supplementary note 50) The liquid crystal display device according to supplementary note 43, wherein the second domain regulating means is an electrode slit extending in a direction different by 0 to 45 degrees from a direction of the liquid crystal domain.
[0224]
【The invention's effect】
As explained above, 45 degrees, 135 degrees The proportion of the region where the liquid crystal molecules tilt in the orientation, 225 degrees, 315 degrees By changing the ratio of the region where the liquid crystal molecules are inclined in the azimuth direction to an appropriate ratio, it is possible to display appropriately even when the screen is viewed from the upper direction or the lower position.
[Brief description of the drawings]
FIGS. 1A and 1B are diagrams showing pixel electrode patterns according to a first embodiment of the present invention.
FIG. 2 is a perspective view showing a basic configuration of an MVA liquid crystal display device.
FIG. 3 is a diagram illustrating a viewing angle characteristic of black and white contrast of an MVA type liquid crystal display device.
FIGS. 4A to 4C are diagrams for explaining the reason and principle of causing a whitish phenomenon on the display surface. FIGS.
FIGS. 5A and 5B are diagrams showing characteristics of transmitted light amount-applied voltage.
6A and 6B are diagrams illustrating pixel electrode patterns. FIG.
FIG. 7 is a diagram showing a contact region for connecting a pixel electrode and an auxiliary capacitor.
FIGS. 8A and 8B are diagrams illustrating a basic configuration of a liquid crystal display device.
FIG. 9 is a diagram showing a contact region for connecting a pixel electrode and a TFT.
FIG. 10 is a cross-sectional view of a TFT.
FIG. 11 is a cross-sectional view of a liquid crystal display device.
12A is a plan view of a liquid crystal display device, and FIG. 12B is a cross-sectional view of the liquid crystal display device.
13A and 13C are diagrams showing pixel electrode patterns, and FIG. 13B is a cross-sectional view of a TFT substrate.
FIG. 14 is a diagram showing a four-part alignment MVA liquid crystal display device.
FIG. 15 is a diagram showing a technique for aligning liquid crystal molecules by providing a Y-shaped slit on a counter substrate.
FIG. 16 is a diagram showing a liquid crystal display device according to a second embodiment of the present invention.
FIGS. 17A and 17B are diagrams illustrating a principle configuration in which liquid crystal molecules are tilted when a minute slit is provided.
FIG. 18 is a diagram for explaining an example in which the Y-angle of the pixel electrode is changed.
FIGS. 19A to 19C are diagrams for explaining modifications of the shape of fine slits.
FIGS. 20A and 20B are diagrams for explaining the effect when the pixel electrode has a tapered shape. FIGS.
FIGS. 21A and 21B are a plan view and a cross-sectional view of a liquid crystal display device utilizing an oblique electric field from the Cs line, respectively.
FIG. 22 is a plan view of another liquid crystal display device.
FIG. 23A is a diagram showing a configuration in which electrodes are formed obliquely, and FIG. 23B is a diagram showing a configuration in which an oblique electric field from a Cs line is utilized.
FIG. 24 is a diagram showing a liquid crystal display device when a λ / 4 plate is applied.
25A is a plan view of a liquid crystal display device, FIG. 25B is a diagram showing a transmitted light amount distribution when a λ / 4 plate is not applied, and FIG. 25C is a diagram showing a λ / 4 plate. It is a figure which shows the transmitted light amount distribution at the time of applying.
FIG. 26 is a diagram showing a film configuration for realizing a wide viewing angle.
FIG. 27 is a diagram showing a film configuration for realizing high luminance.
FIGS. 28A and 28B are diagrams showing film configurations and characteristics according to the third embodiment of the present invention. FIGS.
FIGS. 29A and 29B are diagrams showing a film configuration and characteristics according to the present embodiment.
FIGS. 30A and 30B are diagrams showing the film configuration and characteristics according to the present embodiment.
FIGS. 31A and 31B are diagrams showing the film configuration and characteristics according to this embodiment. FIGS.
FIG. 32 is a diagram showing viewing angle characteristics.
FIG. 33 is a diagram showing a film configuration.
FIG. 34 is a view showing a film configuration according to a fourth embodiment of the present invention.
FIG. 35 is a diagram showing another film configuration.
FIG. 36 is a diagram showing another film configuration.
FIG. 37 is a diagram showing a liquid crystal display device with two-part alignment.
FIGS. 38 (A) to (C) are diagrams showing problems of the bipartite alignment. FIGS.
FIG. 39 is a plan view showing a liquid crystal display device according to a fifth embodiment of the present invention.
FIGS. 40A and 40B are views for explaining a λ / 4 plate.
41A and 41B are cross-sectional views of the liquid crystal display device of the present embodiment.
FIG. 42 is a diagram showing a configuration in which a scattering layer is added to a film.
FIG. 43 is a diagram showing a measurement result with color when a display that is white in front is observed from an oblique direction.
44 (A) and 44 (B) are diagrams showing an IPS liquid crystal display device.
45A and 45B are diagrams showing an electrode configuration of an MVA liquid crystal display device.
46A to 46D are diagrams showing alignment of liquid crystal molecules.
FIG. 47 is a diagram showing a four-domain electrode configuration.
FIG. 48 is a diagram showing a film configuration.
49A to 49C are diagrams showing a configuration of a pixel electrode.
50A to 50D are diagrams showing alignment control by banks and slits.
FIGS. 51A to 51C are diagrams showing alignment control by an auxiliary bank and auxiliary slits.
52 (A) and 52 (B) are diagrams showing alignment control by fine slits.
FIG. 53 is a diagram illustrating orientation control by a bank of a cross pattern.
54 is a diagram showing a layout of a liquid crystal display device. FIG.
FIG. 55 is a diagram showing a layout of a liquid crystal display device.
FIG. 56 is a diagram showing a layout of a liquid crystal display device.
FIG. 57 is a diagram showing a layout of a liquid crystal display device.
FIG. 58 is a diagram showing a layout of a liquid crystal display device.
FIG. 59 is a diagram showing a layout of a liquid crystal display device.
FIG. 60 is a diagram showing a layout of a liquid crystal display device.
FIG. 61 is a diagram showing a layout of a liquid crystal display device.
FIG. 62 is a diagram showing a layout of a liquid crystal display device.
FIG. 63 is a diagram showing a layout of a liquid crystal display device.
FIG. 64 is a diagram showing a layout of a liquid crystal display device.
FIG. 65 is a diagram showing a layout of a liquid crystal display device.
66 is a diagram showing a layout of a liquid crystal display device. FIG.
FIG. 67 is a diagram showing a layout of a liquid crystal display device.
FIG. 68 is a diagram showing a layout of a liquid crystal display device.
FIG. 69 is a diagram illustrating a bank layout.
[Explanation of symbols]
101,102 Orientation region
103 pixel area
111 pixel electrodes
112 Contact area
113 data lines
114 Gate line
121,122 Orientation region
123 Pixel electrode
131,132 Orientation region
133 pixel area
141-144 Orientation region
201 TFT substrate
202 Counter substrate
203,204 bank

Claims (1)

  1. A pair of substrates;
    The liquid crystal molecules are sandwiched between the pair of substrates so that the liquid crystal molecules are vertically aligned with respect to the substrate when no voltage is applied between the substrates, and the liquid crystal molecules are substantially parallel to the substrate by applying a voltage between the substrates. A liquid crystal display device having a liquid crystal layer falling in a plurality of directions,
    When the voltage is applied, the liquid crystal layer defines an angle counterclockwise when the right direction of the screen is 0 degree, and the orientation direction of the liquid crystal molecules is regulated by the pixel electrode to 45 degrees, 135 degrees, and 225 degrees. And the ratio of the region in which the liquid crystal molecules are tilted in the four directions of 315 degrees and the liquid crystal molecules are tilted in the directions of 45 degrees and 135 degrees, and the ratio of the regions in which the liquid crystal molecules are tilted in the directions of 225 degrees and 315 degrees are different.
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