JP3514219B2 - Multi-domain liquid crystal display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-domain liquid crystal display device having high contrast and excellent in a visual angle characteristic, without increasing complex processes such as micro-fabrication process of a common electrode, and requiring a high degree of sticking technology. SOLUTION: In the multi-domain liquid crystal display device, a control electrode 73 is connected with a source terminal 57 which is one of the terminals of a TFT 54 as a switching element, and a pixel electrode 71 with an opening part 74 formed therein has coupling capacitance 126 across the control electrode 73, and a divided signal voltage is applied to the pixel electrode 71 through the coupling capacitance 126.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-domain liquid crystal display device, and more particularly to a multi-domain liquid crystal display device having excellent viewing angle characteristics.

[0002]

2. Description of the Related Art Twisted Nematic (Twisted Nematic) which has been widely used in the past
() Type liquid crystal display device, the liquid crystal molecules are twisted in parallel with the substrate surface from the "white" display state when no voltage is applied, and the liquid crystal molecules are aligned in the direction of the electric field depending on the applied voltage. By changing the direction, the “white” display state gradually changes to the “black” display state.
However, due to the behavior of liquid crystal molecules due to this voltage application, T
There is a problem that the N-type liquid crystal display device has a narrow viewing angle. This problem of a narrow viewing angle becomes particularly remarkable in the rising direction of liquid crystal molecules in halftone display.

As a method for improving the visual field characteristics of a liquid crystal display device, a technique disclosed in Japanese Patent Laid-Open No. 6-43461 has been proposed. FIG. 47 is a schematic partial cross-sectional view illustrating an example of the configuration of a liquid crystal display device according to the technique disclosed in the publication. In this technique, a liquid crystal cell in which a liquid crystal 21 having a negative dielectric anisotropy is homeotropically (vertically) aligned, and two polarizing plates (not shown) installed so that their polarization axes are orthogonal to each other are formed. By using the common electrode 81 having the opening 74 sandwiched between them, the electric field is obliquely concentrated in each pixel, whereby each pixel is made into two or more domains, so-called multi-domain, and the viewing angle characteristics are improved. ing. Further, in this technique, an optical compensator may be used as necessary to improve the viewing angle characteristic of black. Further, not only in the homeotropically aligned liquid crystal cell but also in the TN-oriented cell, by using a common electrode having an opening, an oblique electric field is generated to divide each pixel into two or more domains. , The viewing angle characteristics have been improved.

Further, in the technique disclosed in Japanese Patent Laid-Open No. 7-199190, an opening (orientation control window) is provided in the common electrode and an orientation control electrode is provided so as to surround the pixel electrode, and the pixel electrode peripheral portion is provided. The oblique electric field at is emphasized to stabilize the liquid crystal domain.

In addition, in Japanese Unexamined Patent Publication No. 7-230097, an alignment control electrode integrated with a gate line is provided on a pixel electrode, and each pixel is made into two or more liquid crystal domains by an oblique electric field from this alignment control electrode. The viewing angle characteristics are improved.

Further, in the technique disclosed in Japanese Patent Application Laid-Open No. 10-20323, a technique of forming a plurality of liquid crystal domains by providing an opening in a pixel electrode and disposing a control electrode at the position of the opening is disclosed. Disclosure.

Further, in Japanese Patent Laid-Open No. 10-301114, in a liquid crystal cell in which a liquid crystal having a negative dielectric constant is homeotropically aligned, a projection is provided on an alignment film, and the projection causes the tilt direction of the liquid crystal when a voltage is applied. Techniques for controlling and operating by dividing into two or more liquid crystal domains have been devised.

[0008]

However, among these techniques, in the technique having an opening in the common electrode as disclosed in JP-A-6-43461,
In addition to the "microfabrication process such as a photoresist process for the common electrode" which is not required in the normal manufacturing process of a mono-domain type TN type liquid crystal display device,
There is a problem that an advanced bonding technique for the upper and lower substrates is required. This problem is caused by the thin film transistor (Thin)
This is a particularly serious problem in the case of an active matrix liquid crystal display device using a switching element such as a film transistor (TFT). That is, in a normal active matrix liquid crystal display device, since a switching element (active element) such as a thin film transistor is manufactured on one transparent substrate (TFT substrate), a fine processing step such as a photoresist step is required. There is no need to perform fine processing on the other transparent substrate (counter substrate) side electrode, which is usually called "common electrode", because it is only one side of the TFT substrate for manufacturing the switching element, and the common electrode is formed on the entire surface. It has only been done. However, in the conventional technology having an opening in the common electrode, even for the "common electrode" which normally does not require fine processing, a fine processing step such as a photoresist step is required, and the number of steps increases, Advanced bonding technology for the upper and lower substrates will be required.

From such a problem, for example, an opening or a slit is provided in the pixel electrode on the side of the TFT substrate on which a switching element such as a TFT is formed, and an oblique electric field is generated to control the alignment of the liquid crystal. I can think of technology. This is because the pixel electrode on the TFT substrate side originally requires patterning, and in this case, no additional step is required. However, stable liquid crystal domain control is not possible with this configuration. This is because the slope of the electric field around the opening when the common electrode is provided with the opening as in Japanese Patent Laid-Open No. 6-43461 matches the tilt direction of the electric field around the pixel electrode (FIG. 47).
In contrast, when an opening is provided in the pixel electrode on the TFT substrate side, the inclination of the electric field around the opening does not match the inclination direction of the electric field around the pixel electrode.

As disclosed in Japanese Patent Laid-Open No. 7-199190, when the control electrode is provided around the pixel electrode, the inclination of the electric field around the pixel electrode can be emphasized. However, it is necessary to provide an opening in the common electrode on the opposite substrate, and it is necessary to solve the above problem.

On the other hand, as described in Japanese Unexamined Patent Publication No. 7-230097, a diagonal electric field can be generated by disposing a control electrode on a pixel electrode and appropriately setting the potential of the control electrode. However, during so-called inversion driving in which the polarity of the pixel electrode potential is inverted at a constant period, the generation state of the oblique electric field also changes due to the change in the polarity of the pixel electrode potential, so stable and reliable control of the liquid crystal domain cannot be performed. Further, in this configuration, since the control electrode is integrated with the gate bus line, the control electrode potential cannot be changed depending on whether the pixel is turned on or off, that is, the pixel is not turned on (dark display). Even at this time, an electric field in an oblique direction is generated in the control electrode potential, and this electric field causes light leakage around the control electrode, leading to a reduction in display contrast. When a light-shielding layer is provided to shield this light leakage, the aperture ratio is greatly reduced. Further, normally, a DC voltage is applied to the common electrode on the gate bus line during the period excluding the selection period, so that when the control electrode is integrated with the gate bus line, the display area The DC voltage is continuously applied to the liquid crystal layer in the inside, which causes a problem that the reliability of the display element is deteriorated.

Even in the technique as disclosed in Japanese Patent Laid-Open No. 10-20323, in which an opening is provided in a pixel electrode and a control electrode is arranged at that position, a control electrode potential is controlled for each pixel during a display operation. Since it has no
Similar to the technique described in Japanese Patent No. 30097, there is a problem that stable and reliable control of the liquid crystal domain cannot be performed.

As means for solving the above problems in the techniques disclosed in Japanese Patent Application Laid-Open Nos. 7-230097 and 10-20323, for example, a control electrode provided individually for each pixel is used. , A method of controlling with an individual switching element provided in each pixel is conceivable, but in this configuration, it is necessary to provide an individual switching element and a drain bus line corresponding to the pixel electrode and the control electrode, Therefore, the element structure becomes complicated, and it is not realistic in terms of manufacturing cost and manufacturing yield.

Further, in the method of providing the projection on the alignment film as described in Japanese Patent Laid-Open No. 10-301114, the effect of area division by the projection works only in the vicinity of the projection. Therefore, in order to realize reliable area division, it is necessary to provide protrusions not only on the alignment film on the TFT substrate on one side where the switching elements are formed, but also on the alignment film on the opposite substrate side, which is also a significant step. However, there is a problem in that the number of substrates is increased and accurate bonding of both substrates is required.

The present invention has been made in view of the above-mentioned circumstances, and has the problems of the above-mentioned conventional techniques, that is, the number of complicated processes such as the microfabrication process of the common electrode is increased, and the advanced bonding technique is used. It is an object of the present invention to provide a multi-domain liquid crystal display device having high contrast and excellent viewing angle characteristics without requiring

[0016]

In order to solve the above-mentioned problems, the invention according to claim 1 has a liquid crystal sandwiched between a pair of substrates and a plurality of liquid crystals formed on one side of the substrates and extending in the lateral direction. And a plurality of drain bus lines extending in the vertical direction, a plurality of pixels are arranged in a matrix corresponding to each intersection of the gate bus line and the drain bus line, and the pixel each of, the comprises a switching element, a pixel electrode, and a control electrode for by generating an electric field in an oblique direction to form a plurality of alignment regions in one pixel with respect to the liquid crystal, the other of said substrate
According to a multi-domain liquid crystal display device having a common electrode on one side, the control electrode is connected to one terminal of the switching element, and the pixel electrode has a coupling capacitance between the pixel electrode and the control electrode. A signal voltage is applied to the control electrode from the corresponding drain bus line via the corresponding switching element when the corresponding gate bus line is selected, and the signal voltage is applied to the pixel electrode via the coupling capacitance. that the partial pressure of is configured to be applied
Therefore, the voltage applied to the control electrode is applied to the pixel electrode.
The absolute value is larger than the applied voltage, and
The oblique electric field so that it spreads outward from the control electrode.
The feature is that a plurality of alignment regions are formed within one pixel .

The invention according to claim 2 relates to the multi-domain liquid crystal display device according to claim 1, wherein the pixel electrode and the control electrode are formed so that the pixel electrode is a lower layer via an insulating film. It is characterized by being.

The invention according to claim 3 relates to the multi-domain liquid crystal display device according to claim 1 or 2, characterized in that an opening is formed in the pixel electrode.

The invention according to claim 4 relates to the multi-domain liquid crystal display device according to claim 3, characterized in that the control electrode causes an electric field to control the alignment state of the liquid crystal from the opening. There is.

The invention according to claim 5 relates to the multi-domain liquid crystal display device according to any one of claims 1 to 4, further comprising a common capacitance line for adding capacitance to the pixel electrodes. It is characterized by that.

The invention according to claim 6 relates to the multi-domain liquid crystal display device according to claim 5, characterized in that the common capacitance line is disposed at a position corresponding to the opening.

The invention according to claim 7 relates to the multi-domain liquid crystal display device according to claim 5 or 6, wherein an additional capacitance of a predetermined capacitance is provided between the pixel electrode and the common capacitance line. It is characterized by that.

The invention according to claim 8 relates to the multi-domain liquid crystal display device according to any one of claims 1 to 7, characterized in that at least a part of the control electrode is formed of a transparent electrode. .

The invention according to claim 9 relates to the multi-domain liquid crystal display device according to claim 1, characterized in that quarter-wave plates are arranged on both sides of the liquid crystal.

The invention described in claim 10 is the same as claim 1.
According to the multi-domain liquid crystal display device described above, each of the liquid crystals has a quarter-wave plate on both sides, and the optical axes of the quarter-wave plates are arranged to be orthogonal to each other. It has a feature.

The invention described in claim 11 is the same as claim 1.
The multi-domain liquid crystal display device according to any one of items 1 to 10, wherein the switching element is a bottom-gate TFT.

The invention according to claim 12 is the same as claim 1
The multi-domain liquid crystal display device according to any one of items 1 to 10, wherein the switching element is a TFT having a top gate structure.

The invention according to claim 13 is the same as claim 1.
The multi-domain liquid crystal display device according to 1 or 12,
The insulating film is characterized by being formed integrally with an insulating film that protects the TFT.

The invention according to claim 14 is the same as claim 1
The multi-domain liquid crystal display device according to 2 or 13,
The control electrode is formed integrally with the source terminal of the TFT.

The invention according to claim 15 is the same as claim 3
The multi-domain liquid crystal display device described is characterized in that the opening is formed in a window shape.

The invention according to claim 16 is the same as claim 3
The multi-domain liquid crystal display device described is characterized in that the opening is formed so as to make a cut from one side or both sides of the pixel electrode.

The invention according to claim 17 is the same as claim 1
The multi-domain liquid crystal display device described above is characterized in that a resistance element for discharging electric charge accumulated in the pixel electrode is provided between the pixel electrode and the control electrode.

The invention according to claim 18 is the same as claim 1.
According to the multi-domain liquid crystal display device of item 7, the resistance element has a substantially finite resistance value.

The invention according to claim 19 is the invention according to claim 5.
The multi-domain liquid crystal display device described above is characterized in that a resistance element having a substantially finite resistance value is provided between the pixel electrode and the common capacitance line.

The invention according to claim 20 is the same as claim 1
The above-mentioned multi-domain liquid crystal display device is characterized in that the operation mode of the liquid crystal is a TN mode in which a liquid crystal having a positive dielectric anisotropy is twisted and aligned.

The invention of claim 21 is the same as claim 2 of the invention.
0. The multi-domain liquid crystal display device according to 0, characterized in that the liquid crystal has a spontaneous chiral property .

The invention according to claim 22 is the same as claim 2
0. The multi-domain liquid crystal display device according to 0, characterized in that the liquid crystal is non-spontaneous chiral .

The invention of claim 23 is the same as claim 1
The multi-domain liquid crystal display device described above is characterized in that the operation mode of the liquid crystal is a homogeneous mode in which liquid crystal having positive dielectric anisotropy is uniformly aligned.

The invention according to claim 24 is the same as claim 1
The multi-domain liquid crystal display device described above is characterized in that the operation mode of the liquid crystal is a VA mode in which liquid crystal having a negative dielectric anisotropy is homeotropically (vertically) aligned.

A twenty-fifth aspect of the present invention relates to the multi-domain liquid crystal display device according to the first, second or third aspect, wherein the pixel electrode is formed of a plurality of minute pixel electrodes each having a square shape, The control electrodes are arranged along the sides, and the remaining three sides are openings or pixel electrode end portions.

The invention according to claim 26 relates to the multi-domain liquid crystal display device according to claim 1, 2 or 3, wherein the pixel electrode is formed of a plurality of minute pixel electrodes each having a quadrangular shape, The control electrodes are arranged along the sides, and the remaining two sides are openings or pixel electrode end portions.

The invention according to claim 27 is the same as claim 2
The multi-domain liquid crystal display device according to 5 or 26,
The quadrangle is characterized by being substantially square.

The invention according to claim 28 relates to the multi-domain liquid crystal display device according to claim 1, 2 or 3, wherein the pixel electrode is formed of a plurality of minute pixel electrodes each having a triangular shape. The control electrodes are arranged along the two sides of the above, and the remaining one side is the opening or the pixel electrode end opening.

A twenty-ninth aspect of the present invention relates to the multi-domain liquid crystal display device according to the first, second or third aspect, wherein the pixel electrode is formed of a plurality of minute pixel electrodes each having a triangular shape. The control electrode is arranged along one side of the above, and the remaining two sides are openings or openings of the pixel electrode end.

The invention according to claim 30 relates to the multi-domain liquid crystal display device according to claim 1, 2 or 3, wherein the pixel electrode is formed of a plurality of minute pixel electrodes each having a pentagonal shape. The control electrodes are arranged along two sides of the above, and the remaining three sides are openings or pixel electrode end openings.

The thirty-first aspect of the present invention relates to the multi-domain liquid crystal display device according to the first, second or third aspect, wherein the pixel electrode is formed of a plurality of minute pixel electrodes. It is characterized in that two or more kinds of the minute pixel electrodes according to any one of claims 25 to 30 are combined.

The invention of claim 32 is the same as claim 2
7. In the multi-domain liquid crystal display device according to 7, the ratio of the control electrode voltage applied to the control electrode to the pixel electrode voltage applied to the pixel electrode is 1.1 to 1 with reference to the voltage of the common electrode. It is characterized by being set to 0.4.

Further, the invention of claim 33 is based on claim 32.
The multi-domain liquid crystal display device described above is characterized in that the ratio of the electrode voltage to the pixel electrode voltage is set to 1.2 to 1.4.

The invention according to claim 34 is the same as claim 3
The multi-domain display device according to the third aspect is characterized in that the ratio of the control electrode voltage to the pixel electrode voltage is set to about 1.3.

Further, the invention of claim 35 is the same as claim 2
The multi-domain liquid crystal display device described in Item 7, characterized in that the size of the fine alignment region in which the liquid crystal has a substantially single alignment is approximately 20 μm 2 or less.

The invention of claim 36 is the same as that of claim 2
According to the multi-domain liquid crystal display device of item 7, the size of the fine alignment region in which the liquid crystal has a substantially single alignment is approximately 40 μm square or more.

The invention according to claim 37 is the same as claim 2
The multi-domain liquid crystal display device according to 7, wherein the size of the fine alignment region in which the liquid crystal has a substantially single alignment is 20 to 40 μm.
It is characterized by being m square.

The invention according to claim 38 is the same as claim 1.
The multi-domain liquid crystal display device according to 1 or 12,
By superimposing a coupling capacitance terminal electrically connected to either one of the pixel electrode or the control electrode and another electrode not connected to the coupling capacitance terminal via a gate insulating film, It is characterized in that it constitutes at least a part of the coupling capacitance.

The invention according to claim 39 is the invention according to claim 7.
According to the multi-domain liquid crystal display device described above, an additional capacitance terminal electrically connected to either one of the pixel electrode or the common capacitance line and the other not connected to the additional capacitance terminal are provided with a protective insulating film. It is characterized in that at least a part of the additional capacitance is formed by superimposing the additional capacitances.

The invention according to claim 40 is the invention according to claim 7
According to the multi-domain liquid crystal display device described above, an additional capacitance terminal electrically connected to either one of the pixel electrode or the common capacitance line and the other not connected to the additional capacitance terminal are provided with a gate insulating film. It is characterized in that at least a part of the additional capacitance is formed by superimposing the additional capacitances.

The invention described in Item 41 is the same as Item 1
The multi-domain liquid crystal display device described above is characterized in that a discharging element for discharging the electric charge accumulated in the pixel electrode is arranged on the gate bus line corresponding to the preceding stage of an arbitrary pixel.

The invention according to claim 42 is the invention according to claim 4
In the multi-domain liquid crystal display device according to 1, the protective insulating film is removed from a portion of the opening provided in the pixel electrode, the portion corresponding to the opening on which the control electric field from the control electrode arranged in the lower layer acts. It is characterized by that.

Further, the invention according to claim 43 has a liquid crystal sandwiched between a pair of substrates, and a plurality of pixels arranged in a matrix on one side of the substrates, each of the pixels comprising: a switching element, a pixel electrode, together with the by generating an electric field in an oblique direction to the liquid crystal and a control electrode for forming a plurality of alignment regions in one pixel, the group
According to a multi-domain liquid crystal display device having a common electrode on the other side of a plate, the control electrode is connected to one terminal of the switching element, and the pixel electrode has a coupling capacitance with the control electrode. Then, a signal voltage is applied to the control electrode via the corresponding switching element,
Since the voltage division of the signal voltage is applied to the pixel electrode via the coupling capacitance, the absolute value of the voltage applied to the control electrode is greater than the voltage applied to the pixel electrode. It is characterized in that a large electric field is generated so as to spread outward from the control electrode, and a plurality of alignment regions are formed in one pixel.

[0059]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. The description will be specifically made using the embodiments. First Embodiment FIG. 1 is a schematic plan view showing the configuration of a pixel (repeating unit) of the multi-domain liquid crystal display device according to the first embodiment of the present invention, and FIG. 2 is a schematic view taken along the line AA ′ in FIG. Partial sectional view, FIG. 3 is a schematic partial sectional view taken along line BB ′ of FIG. 1,
4 is a schematic partial cross-sectional view taken along the line CC ′ of FIG. 1, FIG. 5 is an equivalent circuit diagram of a pixel of the multi-domain liquid crystal display device, and FIGS. 6 and 7 are manufacturing methods of the multi-domain liquid crystal display device. FIG. 7 is a process drawing showing the step order. The multi-domain liquid crystal display device of this example, as shown in FIGS.
One pixel is formed by a unit of a region surrounded by a plurality of gate bus lines 55 extending in the horizontal direction and a plurality of drain bus lines 56 extending in the vertical direction, and each pixel is formed on the first substrate 11. , Are repeatedly arranged in a matrix in the vertical and horizontal directions.

Each pixel has a TFT 54, a pixel electrode 71 and a control electrode 73. The TFT 54 has a bottom gate structure in which the gate is located below the source and drain, and amorphous silicon, polysilicon, or the like can be used as an active layer (semiconductor layer), and it should be formed by a self-alignment technique. You can The pixel electrode 71 is electrically floating, and the control electrode 73
And the common capacitance line 72 and the inter-layer insulation film 63 and the gate insulation film 61, respectively, to couple the coupling capacitance 126 and the additional capacitance 12.
Forming 7. The TFT 54 is covered with a protective insulating film 65. Silicon nitride or the like is used for the interlayer insulating film 63, the gate insulating film 61, and the protective insulating film 65. Here, the common capacitance line 72 is provided to add capacitance to the pixel electrode 71.

The capacitances of the coupling capacitance 126 and the additional capacitance 127 can be set to desired values by parameters such as the material, size and thickness of the interlayer insulating film 63 and the gate insulating film 61. The pixel electrode 71 and the control electrode 73 are made of transparent electrodes and are made of ITO (Indium Tin Oxide).
Etc. materials are used. The control electrode 73 is connected to the source terminal 57 of the TFT 54. The control electrode 73 is a TFT
It is also possible to form it integrally with the source terminal of 54. The gate bus line 55, the source terminal 57, the drain terminal 58, and the common capacitance line 72 are made of a metal film such as chromium. A common electrode 81 is formed on the second substrate 12 and is overlaid on the first substrate 11 so as to face the first substrate 11 with a predetermined gap. Both boards 11, 12
A liquid crystal 20 is sandwiched between them. Although the TFT 54 is shown as a bottom gate structure, it may have a top gate structure in which the gate is arranged above the source and the drain, as in a fifth embodiment described later.

Further, in this example, the common capacitance line 72 for adding capacitance to the pixel electrode 71 is provided, but the coupling between the pixel electrode 71 and the control electrode 73 in FIG. If the necessary potential difference can be obtained between the capacitor 126 and the liquid crystal capacitor 125 between the pixel electrode 71 and the common electrode 81, the common capacitor line 72 need not be provided.

In this example, the gate bus line 55
At the moment when is selected, the TF from the drain bus line 56
The signal voltage is written to the control electrode 73 connected to the source terminal 57 via T54. At this time, the potential of the floating pixel electrode 71 is set to a predetermined potential between the control electrode 73 and the common capacitance line 72 according to the capacitance ratio of the coupling capacitance 126 to the additional capacitance 127 and the liquid crystal capacitance 125. The common capacitance line 72 is, for example, the second substrate 1
It may be configured to have the same potential as that of the common electrode 81 on the upper part 2, or may be connected to the gate bus line of the preceding stage or the like. In this example, the control electrode 73, the pixel electrode 71,
Since the potential relationship of the common electrode 81 is in the order shown in this list or the reverse order thereof, the pixel electrode 71 and the control electrode 73,
The liquid crystal driving electric field E1 generated between the common electrode 81 and the common electrode 81 is obliquely generated so as to spread outward from the control electrode 73, as shown in FIG.

Hereinafter, a VA (Vertical Align) in which homeotropically aligned liquid crystal having a negative dielectric anisotropy is aligned.
The operation will be described by taking the case of the H. The liquid crystal 20 (or liquid crystal molecules 21) interposed between the first substrate 11 and the second substrate 12 changes its alignment state by the liquid crystal driving electric field E1. In this example, the liquid crystal driving electric field E1 is applied to the control electrode 73 as described above.
The liquid crystal molecules 21 change their alignment directions to different directions on both sides of the control electrode 73, as shown in FIGS. 3 and 4. Therefore, the liquid crystal molecule 2
Regions (liquid crystal domains) having different tilt directions of 1 mutually compensate for the viewing angle characteristics, and as a whole, symmetrical viewing characteristics can be obtained. In the description here, the liquid crystal seen as a bulk is referred to as the liquid crystal 20 and the individual liquid crystal molecules are referred to as the liquid crystal molecules 21, but this difference is not so important in the present invention.

As described above, in this example, the liquid crystal 20
The operation mode was described in the case of the VA mode in which the liquid crystal having the negative dielectric anisotropy was homeotropically aligned, but other than this, the liquid crystal having the positive dielectric anisotropy was twist-aligned. A TN mode or a homogeneous mode in which a liquid crystal having a positive dielectric anisotropy is uniformly aligned may be used. T
When the N mode is selected, the liquid crystal may have a spontaneous chiral property or an involuntary chiral property. In the case of the non-spontaneous chiral property, the liquid crystal driving electric field E1 described above can be divided into a plurality of regions having different chiral directions to operate. In order to stabilize the liquid crystal domain, it is possible to mix a polymer compound with the liquid crystal. Further, it is possible to stabilize the domain by adding a monomer to the liquid crystal to form the domain and then polymerizing the domain.

As shown in FIG. 4, by forming an appropriate opening 74 in the pixel electrode 71, formation of the liquid crystal domain can be made more reliable. The opening 74 may be formed in a window shape, or may be formed so as to be cut in from one side or both sides of the pixel electrode 71. Of course, the opening 7
The object of the present invention can be achieved without providing 4. It is also possible to provide a color layer (not shown) or a light shielding layer (not shown) on the first substrate 11 or the second substrate 12 as in a fourth embodiment described later. It is also possible to form a part or the whole of the common capacitance line 72 with transparent electrodes.

Next, with reference to FIGS. 6 and 7, a method of manufacturing the multi-domain liquid crystal display device of this example will be described in the order of steps. First, as shown in FIG. 6A, chromium is sputter-deposited on the entire surface of the first substrate 11 made of glass, and the photolithography technique is used to pattern chromium into a desired shape. 55 and the common capacitance line 72 are formed. Then, CVD (Ch
A gate insulating film 6 is formed by depositing silicon nitride on the entire surface by an electronic vapor deposition method.
1 was formed.

Next, as shown in FIG. 6B, after depositing amorphous silicon on the entire surface by the CVD method, the active layer 64 was formed by patterning the amorphous silicon into a desired shape by the photolithography technique. Next, after chromium was deposited on the entire surface by sputtering, the chromium was patterned into a desired shape by a photolithography technique to form a drain bus line 56, a drain terminal 58, and a source terminal 57. Next, after depositing ITO on the entire surface by sputtering, the ITO is formed by photolithography technology.
Was patterned into a desired shape to form a pixel electrode 71 having an opening 74. The pixel electrode 71 becomes floating as described above. As described above, the TFT 54 was formed on the first substrate 11.

Next, as shown in FIG. 7C, a silicon nitride film is formed on the entire surface by a CVD method, and then the silicon nitride is patterned into a desired shape by a photolithography technique to form the interlayer insulating film 63 and the TFT 54. A protective insulating film 65 was formed, and a contact hole 59 was formed to expose the source terminal 57. In this case, the interlayer insulating film 63 and the protective insulating film 65 may be integrally formed. Next, ITO was sputtered on the entire surface, and then the ITO was patterned into a desired shape by a photolithography technique to form a control electrode 73. The control electrode 73 is connected to the source terminal 57 via the contact hole 59.

Next, as shown in FIG. 7D, R (Re
d), G (Green), B (Black) color layers and a black matrix (not shown) are formed, and I is formed thereon.
After forming TO by sputtering, the common electrode 81 was formed by patterning ITO into a desired shape by a photolithography technique.

First substrate 11 prepared as described above
An alignment film (not shown) for vertical alignment was formed on each of the first and second substrates 12. As the alignment film material, SE-1211 manufactured by Nissan Chemical Co., Ltd. was used. Next, the first substrate 11
A sealing material (not shown) is linearly applied on the top surface, and spherical spacers (not shown) are sprinkled on the second substrate 12 to bond the two substrates 11 and 12 to each other and heat the sealing material. Cured. Next, after cutting the structure in which the first substrate 11 and the second substrate 12 are integrated by the sealing material into individual panel shapes, nematic liquid crystal having negative dielectric anisotropy is injected from the injection hole. After the injection, the injection hole was sealed with a photo-curing resin. Next, after a negative compensation film is attached to both sides of the panel, a polarizing plate is further attached to both sides so that their transmission axes are orthogonal to each other, and a peripheral drive circuit is attached to form a module. As shown in
The multi-domain liquid crystal display device of this example was completed.

The planar shape of each component of the multi-domain liquid crystal display device manufactured by the above manufacturing method is as shown in FIG. 1, and the size of the pixel is approximately 100 μm in width × 300 μm in length. The planar shape of each component is not limited to the shape shown in FIG. 1, and various shapes can be considered as shown in FIG. 20 described later.

In the multi-domain liquid crystal display device of this example, when the deflection plates are arranged so that their transmission axes are orthogonal to each other, in each of the main liquid crystal alignment regions, the tilting directions of the liquid crystal molecules 21 are on both sides. A good bright state can be displayed by applying the liquid crystal driving electric field E1 because it coincides with the direction that bisects the transmission axis, that is, the upper, lower, left, and right directions. May occur. For the cause of the dark line, see the second section below.
An example will be described. When the generation of dark lines is a problem, an optical anisotropic medium called a quarter-wave plate is inserted between the polarizing plate and the liquid crystal 20 so that circular polarization is incident on the liquid crystal layer. By configuring, it is possible to eliminate the occurrence of dark lines. Further, in this case, the control electrode 73 may be composed of a transparent electrode.

As described above, according to the multi-domain liquid crystal display device of this example, the control electrode 73 is connected to the source terminal 57 which is one terminal of the TFT 54 serving as a switching element, and the pixel in which the opening 74 is formed is formed. The electrode 71 has a coupling capacitance 126 between itself and the control electrode 73, and
Since the voltage division of the signal voltage is applied to the pixel electrode 71 via the coupling capacitance 126, the periphery of the control electrode 73 and the pixel electrode 71 are operated.
The liquid crystal can be divided into a plurality of regions and operated by the action of an oblique electric field generated around the region. Therefore, it is possible to provide a multi-domain liquid crystal display device having high contrast and excellent viewing angle characteristics without increasing complicated processes such as a microfabrication process of the common electrode or requiring advanced bonding technology.

Second Embodiment FIG. 8 is a schematic plan view showing the structure of a multi-domain liquid crystal display device according to the second embodiment of the present invention, and FIG.
-D 'is a schematic partial cross-sectional view, FIG. 10 is E- of FIG.
It is a typical fragmentary sectional view in E '. The configuration of the multi-domain liquid crystal display device of this example is largely different from the configuration of the first embodiment described above, in that the control electrode is formed so as to be lower than the pixel electrode via the interlayer insulating film. Is. That is, as shown in FIGS. 8 to 10, the multi-domain liquid crystal display device of this example includes the first substrate 1
Pixels (the structure shown in FIG. 8) are repeatedly arranged in a matrix on the upper and lower sides in the vertical direction, and a control electrode 73 made of ITO or the like is also provided via an interlayer insulating film 63 made of silicon nitride or the like. Is formed in a layer below the pixel electrode 71 made of ITO or the like. The pixel electrode 71 is in the floating state as in the first embodiment. Control electrode 73
Can be formed integrally with the source terminal 57 of the TFT 54, which is advantageous in the manufacturing process.
Normally, the source terminal 57 is formed of an opaque metal such as chrome as described above, and therefore the disadvantage that the light transmittance of the element is reduced cannot be avoided. On the other hand, when the control electrode 73 is made of a transparent electrode such as ITO as described above, as shown in FIG. 8, for example, the overlapping portion with the pixel electrode 71 so that the capacitance value of the coupling capacitance 126 becomes sufficiently large. Even if a large value is taken, a sufficient aperture ratio can be secured.

In this example, as described above, the control electrode 73
Is below the pixel electrode 71, but the pixel electrode 71 is provided with an opening 74, and the electric field from the control electrode 73 acts on the liquid crystal through the opening 74, so that the liquid crystal is divided into a plurality of regions. Can be operated. Further, like the first embodiment, the invention is not limited to the bottom gate structure but can be applied to the top gate structure. Other than this, it is substantially the same as the above-described first embodiment. Therefore, in FIGS. 8 to 10, parts corresponding to those in FIGS. 1 to 5 are denoted by the same reference numerals and the description thereof will be omitted.

The opening 74 of the pixel electrode 71 in this example
Like the first embodiment, may be formed in a window shape, or may be formed so as to make a cut from one side or both sides of the pixel electrode 71. By forming an appropriate opening 74 in the pixel electrode 71 in addition to the portion on which the electric field from the control electrode 73 acts, the formation of the liquid crystal domain can be made more reliable. In the opening 74 where the electric field from the control electrode 73 acts, the liquid crystal driving electric field E1 acts so as to spread from the opening 74. However, when the control electrode 73 does not exist in the opening 74, or in FIG. 8 or FIG.
When the common capacitance line 72 exists in the opening 74 as shown in FIG. 7, the liquid crystal driving electric field E1 acts so as to converge to the center of the width of the opening 74.

FIG. 11 is a diagram schematically showing the alignment of the multi-domain liquid crystal in this example, and shows the alignment state of the portion including the pixel electrode 71 and the control electrode 73 of FIG. As shown in FIG. 11, regions having different tilt directions of the liquid crystal molecules 21 are formed with the openings 74 of the pixel electrodes 71 as boundaries, and the alignment of the liquid crystal molecules 21 is caused by the elasticity of the liquid crystal at each region boundary. The azimuth is continuously changing.

In this example, the deflection plates are arranged outside the first substrate 11 and the second substrate, respectively. Various combinations of the transmission axes of the deflecting plates on both sides are possible, and above all, the transmission axes of the deflecting plates on both sides are orthogonal to each other, and
By arranging so that the tilt azimuth of the liquid crystal molecules 21 in the main liquid crystal alignment region coincides with the azimuth that bisects the transmission axis of the deflecting plate orthogonal to each other, bright and high-contrast display can be realized. Further, by inserting an optical compensator called a negative compensator, which has a refractive index in the plane larger than the refractive index in the normal direction of the surface, between the liquid crystal and the deflector, black display is performed. The viewing angle characteristics of can be improved.

FIG. 12 schematically shows a state of transmitted light corresponding to a multi-domain alignment state in this example, and similar to FIG. 11, the pixel electrode 71 of FIG.
7A and 7B show a state of transmitted light in a portion including the control electrode 73. Here, although the pixel electrode 71 and the control electrode 73 are transparent electrodes, since the common capacitance line 72 is usually formed of an opaque metal such as chrome as described above, the area on the common capacitance line 72 is Although light is not actually transmitted, the light shielding by the common capacitance line 72 is neglected in order to explain the relationship between the liquid crystal alignment state and light transmission.

In FIG. 12, the deflecting plates are arranged so as to be orthogonal to each other so that their transmission axes are diagonal to each other in the figure. In such an arrangement, in each of the main liquid crystal alignment regions, the tilt direction of the liquid crystal molecules 21 coincides with the direction that bisects the deflection plate transmission axes on both sides, that is, the upper, lower, left, and right directions in the figure. Therefore, a good bright state can be displayed by applying the liquid crystal driving electric field E1, but a dark line 25 as shown in FIG. 12 is generated at the boundary portion of each liquid crystal alignment region. The dark line 25 corresponds to a portion where the tilt direction of the liquid crystal molecules 21 coincides with the deflecting plate transmission axis direction. Regarding the direction of the transmission axis of the deflector, even if the liquid crystal is tilted in that direction, it does not allow light to pass therethrough.
Occurs.

The dark line 25 as described above does not cause a big problem on the display, but is temporary when, for example, a black display state in which no voltage is applied is changed to a white display state by applying a voltage. A change in orientation, that is, a change in the liquid crystal molecule 21 tilting in a direction defined by the electric field from the control electrode 73 may be followed by a secondary change in orientation in which the liquid crystal molecule 21 changes its tilting direction. In some cases it can be a problem. In this case, after the dark line 25 is generated, its shape and width are changed. The time scale of this secondary orientation change is slower than that of a temporary orientation change, and causes a change in the light transmittance of the corresponding pixel over time. The change in light transmittance with time can be roughly divided into two patterns. One is a case where the change from black to white is substantially delayed, which causes an afterimage. On the other hand, there is a case where the brightness changes once and then becomes gradually dark, and in this case, the brightness of the display in the steady state becomes insufficient.

As described above, when the occurrence of the dark line 25 becomes a problem, an optically anisotropic medium called a quarter-wave plate is inserted between the deflecting plate and the liquid crystal 20 to make the liquid crystal. It is also possible to eliminate the occurrence of the dark line 25 by configuring the layer so that the circular deflection is incident. In this example, since the control electrode 73 is formed of the transparent electrode, the elimination of the dark line 25 of the present invention directly leads to the improvement of the element transmittance and the response characteristic. As the quarter-wave plate, a stretched film of polycarbonate or the like can be used as a single layer or by laminating it, and it is preferable to dispose the stretched films on both sides of the liquid crystal layer so that their optical axes are orthogonal to each other. When a plurality of stretched films, which is referred to as a broadband quarter-wave plate, is used, the corresponding layers may be arranged so as to be orthogonal to each other on both sides of the liquid crystal layer.

Even in the case where a change in transmittance is observed such that it becomes bright once and then gradually darkens in the normal driving method, black is displayed for each frame of display for the purpose of sharpening an image during moving image display. When the drive for inserting the display is performed, such a change with time does not pose a problem.

Also in this example, the operation of the liquid crystal 20 is performed in substantially the same manner as in the first embodiment. Here, especially in the case of the homogeneous mode, the compensation film having negative refractive index anisotropy (the refractive index of the optical axis is small) is adjusted so that its optical axis matches the optical axis of the liquid crystal when no voltage is applied. When used in the normally black mode arranged, good viewing angle characteristics can be obtained. At this time, it is preferable that the retardation of the compensation film and the retardation of the liquid crystal layer have opposite signs and have the same absolute value. It is also possible to improve display contrast and viewing angle characteristics by using a biaxial compensation film.

The method of manufacturing the multi-domain liquid crystal display device of this example can be carried out in accordance with that of the first embodiment described with reference to FIGS. 6 and 7. That is, in FIG. 6B, the control electrode 73 may be formed instead of forming the pixel electrode 71, and in FIG. 7C, the pixel electrode 71 may be formed instead of forming the control electrode 73. . The opening 74 is also formed when patterning the pixel electrode 71. The planar shape of each component of the multi-domain liquid crystal display device manufactured by the above manufacturing method is as shown in FIG. 6, and the size of the pixel is 100 μm in the horizontal direction.
m × length approximately 300 μm. The planar shape of each component is not limited to the shape shown in FIG. 6, and various shapes are conceivable as shown in FIG. 20 described later.

As described above, also with the configuration of this example, it is possible to obtain substantially the same effects as those described in the first embodiment.

[Third Embodiment] FIG. 13 is a schematic partial sectional view showing a structure of a multi-domain liquid crystal display device according to a third embodiment of the present invention (corresponding to FIG. 2 of the first embodiment), and FIG. FIG. 3 is an equivalent circuit diagram of a pixel of the multi-domain liquid crystal display device. The structure of the multi-domain liquid crystal display device of this example is greatly different from the structure of the first embodiment described above in that the pixel electrodes are formed so as not to be completely floating. That is, the multi-domain liquid crystal display device of this example has the structure shown in FIG.
Also, as shown in FIG. 14, in order to prevent charges from being accumulated in the pixel electrode 71 for some reason, a coupling capacitor 12 is formed between the pixel electrode 71 and the control electrode 73 as shown in FIG.
A coupling resistor 1 having a substantially finite resistance value in parallel with 6
For example, a semiconductor film 62 made of amorphous silicon or the like is formed instead of the interlayer insulating film 63 of the first embodiment so that 35 are connected. Then, a desired resistance value can be obtained by doping the semiconductor film 62 with appropriate impurity ions.

When a resistor is connected in parallel to the additional capacitance 127 shown in FIG. 14, the common capacitance line 72 and the pixel electrode 7 are connected.
Instead of the inter-layer insulating film 63, a finite coupling resistance may be connected by forming a semiconductor film 62 of amorphous silicon or the like as described above. Coupling resistance 135
In order to prevent the display from being burned in due to the influence of the electric charge accumulated in the pixel electrode 71 and the occurrence of an afterimage that exceeds the response time of the liquid crystal when a moving image is displayed,
The value is set so that the accumulated charge is discharged. 1 depending on the usage of the liquid crystal display device.
The discharge can be completed within the frame display period, or the discharge can be completed by suspending operation for several seconds to several minutes. Other than this, it is substantially the same as the above-described first embodiment. Therefore, in FIG. 13 and FIG.
-Each component corresponding to the component of FIG. 5 is assigned the same number and its description is omitted.

The method of manufacturing the multi-domain liquid crystal display device of this example can be carried out in accordance with that of the first embodiment described with reference to FIGS. 6 and 7. That is, in the process according to FIGS. 6B and 7C,
After the amorphous silicon is formed on the entire surface by the CVD method and then the active layer 64 is formed by patterning the amorphous silicon by the photolithography technique, the semiconductor film 62 may be formed by patterning the desired shape at the same time. Good.

FIG. 15 is an equivalent circuit showing a pixel of a modified example of the multi-domain liquid crystal display device of this example. In this modification, as shown in the figure, the TFT 141 is formed so as to connect each pixel electrode 71 and the common capacitance line 72, and T
By connecting the gate of the FT 141 to the gate bus line 55 of the preceding stage, the potential of the common capacitance line 72 is set to the pixel electrode 71 at the moment when the gate bus line 55 of the preceding stage is selected.
By writing in, it is possible to discharge the electric charge accumulated in the pixel electrode 71.

As described above, also with the configuration of this example, it is possible to obtain substantially the same effects as those described in the first embodiment.

Fourth Embodiment FIG. 16 is a schematic partial sectional view (corresponding to FIG. 2 of the first embodiment) showing the structure of a multi-domain liquid crystal display device according to the fourth embodiment of the invention. The structure of the multi-domain liquid crystal display device of this example is greatly different from the structure of the first embodiment described above in that the pixel electrode and the control electrode are formed on the color layer and the light shielding layer. That is, in the multi-domain liquid crystal display device of this example, as shown in FIG. 16, the color layer 91 and the light shielding layer 93 are formed on the first substrate 11, and the pixel electrode 71 and the control electrode 73 are formed thereon. The pixel electrode 71 faces the common capacitance line 72 via the capacitance terminal 75. Other than this, it is substantially the same as the above-described first embodiment. Therefore, in FIG. 16, the same numbers are given to the respective units corresponding to the components of FIGS. 1 to 5, and the description thereof will be omitted.

The manufacturing method of the multi-domain liquid crystal display device of this example can be carried out in accordance with that of the first embodiment described with reference to FIGS. 6 and 7. That is, in the process according to FIGS. 6B and 7C, after forming the active layer 64, chromium is sputter-deposited on the entire surface, and then chromium is patterned into a desired shape by a photolithography technique. Then, the drain bus line 56, the drain terminal 58, and the source terminal 57 were formed, and at the same time, the capacitance terminal 75 was formed. Furthermore, T is made by silicon nitride.
The protective insulating film 65 of the FT 54 was formed, the light shielding layer 93 was formed using a black resist, and the R, G, B color layers 91 were formed using a color resist. Subsequently, an overcoat layer 92 was formed and planarized to form a pixel electrode 71, an interlayer insulating film 63, and a control electrode 73. The control electrode 73 is connected to the source terminal 57 and the pixel electrode 71 is connected to the capacitance terminal 75 through contact holes. The pixel electrode 73 is in a floating state while being connected to the capacitance terminal 75.

By forming the semiconductor film 62 between the pixel electrode 71 and the control electrode 73, it is possible to prevent the pixel electrode 71 from completely floating, as in the third embodiment.

As described above, also with the configuration of this example, substantially the same effects as those described in the first embodiment can be obtained.

Fifth Embodiment FIG. 17 is a schematic plan view showing a pixel configuration of a multi-domain liquid crystal display device according to a fifth embodiment of the present invention, FIG.
19 is a schematic partial sectional view taken along line FF ′ in FIG.
FIG. 18 is a schematic partial cross-sectional view taken along line GG ′ of FIG. 17.
The structure of the multi-domain liquid crystal display device of this example is greatly different from the structure of the first embodiment described above in that the TFT as a switching element is formed in a top gate structure. That is, as shown in FIGS. 17 to 19, the multi-domain liquid crystal display device of this example has a TF
The T54 has a top gate structure in which the gate bus line 55 is arranged above the source terminal 57 and the drain terminal 58. Other than this, the first described above
This is almost the same as the embodiment. Therefore, in FIGS. 17 to 19, parts corresponding to the components in FIGS. 1 to 5 are denoted by the same reference numerals and the description thereof will be omitted.

The method of manufacturing the multi-domain liquid crystal display device of this example can be carried out in accordance with that of the first embodiment described with reference to FIGS. 6 and 7. That is, in the process according to FIGS. 6A to 7C,
A drain bus line 56, a drain terminal 58, a source terminal 57, and a control electrode 73 are simultaneously formed by forming a chromium film on the first substrate 11 and patterning it.
Subsequently, an amorphous silicon layer, an insulating layer, and a chromium sputtered film were formed, and these were collectively patterned to form the TFT 54. Further, an interlayer insulating film 63 made of silicon nitride was formed, and then ITO was sputtered and patterned to form the pixel electrode 71. The pixel electrode 71 is in a floating state, and the opening 74 is provided in alignment with the position of the control electrode 73. Next, a gate insulating film 61 and a common capacitance line 72 were formed by continuously forming a film of silicon oxide and ITO by sputtering and collectively patterning.

According to this example, the structure of the TFT 54 is changed from the bottom gate structure to the top gate structure.
As shown in FIG. 19, it is possible to form a multi-domain which is substantially the same as that of the second embodiment described with reference to FIG.

In this case as well, the semiconductor film 62 is formed by replacing the interlayer insulating film 63 between the pixel electrode 71 and the control electrode 73 or the gate insulating film 61 between the pixel electrode 71 and the common capacitance line 72. It is possible that the pixel electrode 71 is not in a completely floating state, as in the third embodiment.

As described above, also with the configuration of this example, substantially the same effects as those described in the first embodiment can be obtained.

Sixth Embodiment FIG. 20 is a diagram showing a planar shape of a combination example of a pixel electrode and a control electrode of a multi-domain liquid crystal display device according to a sixth embodiment of the present invention, and FIGS. 21 and 22 are In a combination example of pixel electrodes and control electrodes of the same multi-domain liquid crystal display device, FIG. 23 is a diagram showing a planar shape of a basic configuration. FIG. 23 shows an example of applying the same basic configuration to the multi-domain liquid crystal display device. It is a figure which shows a planar shape. That is, the pixel electrode 71 and the control electrode 7 of the multi-domain liquid crystal display device of this example
As for the combination example of No. 3, various examples are conceivable as shown in FIGS. Here, FIG.
2 (n) and FIG. 22 (o) to (r), FIG.
The planar shape of the application example of 3 (s) to (y) is the pixel electrode 71.
And a control electrode 73 projected onto a plane. In particular, the control electrode 73 is an opening 74 provided on the pixel electrode 71.
Only the part that can be seen from is drawn.

In this example, the positional relationship between the control electrode 73, the opening 74 provided on the pixel electrode 71, and the end of the pixel electrode 71 is important. In order to explain these positional relationships, the positional relationship on the plan view will be described. First, a basic combination example of the pixel electrode 71, the control electrode 73, and the end portion of the pixel electrode 71 is formed using the unit electrodes shown in FIGS.
FIG. 23 (s)-(r) will be described, and next, an application example in which these unit electrodes are applied to an actual liquid crystal display device,
This will be described with reference to (y). For the sake of explanation, the pixel electrode 71 and the control electrode 73 will be described as if they are on the same plane, but in the multi-domain liquid crystal display device of this example, both electrodes 71, 7 are formed.
3 are on different planes. Note that a structure in which some or all of the electrodes 71 and 73 are on the same plane is also possible if conduction is ensured through contact holes or the like.

The unit electrode shown in FIG. 21I is the pixel electrode 71.
Is a quadrangle and the control electrode 7 is formed along one side of the pixel electrode 71.
3 are arranged, and the remaining three sides of the pixel electrode 71 are openings or pixel electrode end portions 76. In the unit electrode of FIG. 21 (j), the pixel electrode 71 is a quadrangle, the control electrode 73 is arranged along two sides of the pixel electrode 71, and the remaining two sides of the pixel electrode 71 are openings or pixel electrode ends. It is characterized in that it is a part 76. Figure 2
In the unit electrode of 1 (k), the pixel electrode 71 is a quadrangle, and the control electrodes 73 are arranged along the three sides of the pixel electrode 71, and the remaining one side of the pixel electrode 71 is an opening or a pixel electrode end. It is characterized in that it is 76. Figure 21
In the unit electrode of (l), the pixel electrode 71 is triangular, and the control electrode 73 is arranged along two sides of the pixel electrode 71.
The remaining one side of the pixel electrode 71 is an opening or a pixel electrode end 76. In the unit electrode shown in FIG. 21 (m), the pixel electrode 71 has a triangular shape.
The control electrode 73 is arranged along one side of the pixel electrode 71, and the remaining two sides of the pixel electrode 71 are openings or pixel electrode end portions 76. In the unit electrode of FIG. 21 (n), the pixel electrode 71 is a pentagon, and the control electrode 73 is arranged along two sides of the pixel electrode 71, and the remaining three sides of the pixel electrode 71 are openings or pixel electrode ends. It is characterized in that it is a part 76.

Next, the unit electrodes shown in FIGS. 21 (i) to 21 (n) are used as pixel repeating units: horizontal approximately 100 μm × vertical approximately 300 μm.
Regarding the example applied to the multi-domain liquid crystal display device of
Description will be made with reference to application examples of FIGS. The application example of FIG. 23 (s) uses some of the unit electrodes of FIG. 21 (i). That is, a unit electrode (i) and a unit electrode in which the unit electrode (i) is line-symmetric with respect to the control electrode 73 are arranged so as to share the control electrode 73 with each other to form an electrode such as the electrode (o). Then, two electrodes (o) were used to form one pixel electrode of the multi-domain liquid crystal display device. The reason for using the electrode (o) is to control the liquid crystal direction in approximately two directions by the oblique electric field from the control electrode 73 and the oblique electric fields at the left and right ends of the electrode (o). This FIG.
In the application example of (s), the control electrode 73 is made parallel to the long side of the pixel. When applied to the multi-domain liquid crystal display device, the pixel electrode 71 is not divided by the control electrode 73 as shown by the electrode (o), and the pixel electrode 71 on one pixel is set to have the same potential. A joint is provided. The junction is provided so that the pixel electrode 71 on one pixel has the same electric potential because the electrode (o) is formed as shown in FIG.
In the application example of 3 (t), the unit electrode (l) is applied to the application example of FIG. 23 (u), the unit electrode (j) is applied to the application example of FIG. 23 (w),
The unit electrode (k) and the unit electrode (n) are applied to the application example of FIG. 23 (x), and the unit electrode (i), the unit electrode (l) and the unit electrode (j) are applied to the application example of FIG. 23 (y), respectively. The same applies when applied.

In the application example of FIG. 23 (t), the electrode (o) is set to 5
The control electrodes 73 were arranged so that the control electrodes 73 were parallel to the short sides of the pixels to form one pixel electrode of the multi-domain liquid crystal display device. The application example of FIG. 23 (u) is composed of a unit electrode (l). First, four unit electrodes (1) are arranged so as to share the control electrode 73 with each other to form an electrode like the electrode (p), and two electrode (p) are used to form a multi-domain liquid crystal display device. One pixel electrode. The reason why the unit electrode (l) and the electrode (p) are used is that the unit electrode (l) is formed by three oblique electric fields of the oblique electric field from the two control electrodes 73 of the unit electrode (l) and the oblique electric field at the pixel end portion. The upper orientation is controlled in approximately one direction, and the unit electrode (l) is connected to the electrode (p).
This is because by arranging as described above, the directions of the liquid crystal are controlled in approximately four directions.

The application example of FIG. 23 (v) is the unit electrode (l).
And a unit electrode (m). The four unit electrodes (m) were arranged so that the control electrode 73 was on the outer side, and formed into a shape like the electrode (q). The electrode (q) was arranged between two electrodes (p) and used as one pixel electrode of the multi-domain liquid crystal display device. However, in the application example of FIG. 23 (v), in order to ensure the alignment matching between the electrode (p) and the electrode (q), the electrode (p) among the control electrodes 73 outside the electrode (q) is used. The part that touches is removed. As described above, basically, the pixel electrodes are formed by using the unit electrodes (i) to (n), but the shape of the unit electrodes is partially changed in order to ensure the alignment matching as described above. It is also possible.

The application example of FIG. 23 (w) is the unit electrode (j).
It consists of The unit electrode (j) has a substantially square shape, and four unit electrodes (j) are arranged so as to share the control electrode 73 with each other to have a shape like the electrode (r).
Three electrodes (r) were used as one pixel electrode of the multi-domain liquid crystal display device. The reason why the unit electrode (j) and the electrode (r) are used is that the electrode (r) is formed by four oblique electric fields of the oblique electric field from the two control electrodes 73 of the unit electrode (j) and the oblique electric field of the two pixel end portions. This is because the above orientation is controlled in approximately one direction, and the unit electrode (j) is arranged like the electrode (r) to control the liquid crystal direction in approximately four directions. FIG. 23
In the application example of (w), the number of electrodes (r) is set to 3, but the number is not limited to this, and can be arbitrarily designed according to the pixel size and the application.

The application example of FIG. 23 (x) is composed of two unit electrodes (k) and two unit electrodes (n). The quadrangle of the unit electrode (k) was trapezoidal. The control electrode 73 was placed on the upper base of the trapezoid, and the two unit electrodes (k) were arranged so as to share the upper base. The unit electrode (n) was arranged on the oblique side of the electrode thus formed so as to share the control electrode 73 with the unit electrode (k). At the time of combination, the upper base of the trapezoid, that is, a part of the control electrode 73 is hidden in order to ensure alignment matching. As a result, an electrode is formed in which the "Y" type and the "Y" type inverted control electrodes 73 are arranged on the rectangular pixel electrode 71. This was used as one pixel electrode of the multi-domain liquid crystal display device.

The application example of FIG. 23 (y) is formed from three types of unit electrodes: a unit electrode (i), a unit electrode (l), and a unit electrode (j). In the application example of FIG. 23 (y), the unit electrode (i) is a trapezoid, the unit electrode (l) is an isosceles right triangle having a right angle between the control electrodes 73, and the unit electrode (j) is It was a parallelogram. The hypotenuse of the unit electrode (l) is in contact with the upper bottom (opening) of the unit electrode (i), and the lower bottom of the unit electrode (i) and the unit electrode (j)
Share the control electrode 73. Several electrodes thus formed were used as one pixel electrode of a multi-domain liquid crystal display device. Since a part of the minute pixel electrode is an isosceles right triangle, the control electrode 73 and the opening 74 inside the pixel electrode 71 are approximately 4 with respect to the short side of the pixel.
The angle is 5 ° or approximately 135 °. FIG. 23
In any of the application examples of (s) to (y), the pixel electrode is basically formed by using the unit electrode. However, in order to ensure alignment alignment in the entire pixel, the unit electrode is formed. It is also possible to partially change the shape of. A multi-domain liquid crystal display device having the pixel electrodes designed as described above was manufactured. The details of this control electrode can be implemented according to those of the second embodiment.

The orientation state of the application example of FIGS. 23 (s) to 23 (y) described above is shown in micrographs in FIGS. 24 to 30. In FIGS. 24 to 27 and 29, the two polarizing plates are arranged so that the absorption axes of the polarizing plates are orthogonal to each other, and the absorption axis of one polarizing plate is relative to the long side of the pixel. About 45 °
It is set in the direction of. In FIGS. 28 and 30, the arrangement method of the two polarizing plates is such that the absorption axes of the polarizing plates are orthogonal to each other and the absorption axis of one of the polarizing plates is about 0 ° with respect to the long side of the pixel. It is oriented.

According to this example, in any of the application examples shown in FIGS. 23 (s) to 23 (y), the periphery of the control electrode 73, the periphery of the opening 74, and the periphery of the pixel electrode 71 are inclined. Good multi-domain liquid crystal alignment was obtained by the effect of the electric field. In particular, in the pattern of the application example of FIG. 23 (w), the viewing angle characteristics were good, the transmittance was high, and the orientation excellent in stability was obtained. In the application example of FIG. 23 (w), since the unit electrode (j) has a substantially square shape, the liquid crystal is tilted in a diagonal direction. Therefore, the orientation directions of the adjacent unit electrodes (j) are different from each other by approximately 90 °. On the electrode (r), there is a 4-fold symmetrical orientation divided by a “+” type control electrode 73.

As described above, also with the configuration of this example, it is possible to obtain substantially the same effects as those described in the first embodiment.

Seventh Embodiment In the seventh embodiment of the present invention, FIG. 23 shown in the sixth embodiment is used.
In the application example of (w), the influence on the orientation controllability when the control electrode voltage coefficient (control electrode voltage / pixel electrode voltage) is varied was compared and examined. Here, the pixel electrode voltage and the control electrode voltage refer to the voltage of the pixel electrode 71 and the control electrode 73 based on the voltage of the common electrode 81. As described above, the voltage ratio between the pixel electrode voltage and the control electrode voltage is determined by the coupling capacitance 126 between the pixel electrode 71 and the control electrode 73,
Additional capacitance 1 between the pixel electrode 71 and the common capacitance line 72
It is determined by the ratio of 27 and the liquid crystal capacitance 125. Here, when the voltage of the common capacitance line 72 is the same as that of the common electrode 81, (control electrode voltage coefficient) = {(capacitance value of liquid crystal capacitance 125) + (capacitance value of coupling capacitance 126) +
(Capacity value of additional capacity 127) / (capacity value of coupling capacity 126).

The liquid crystal capacitance 125 fluctuates depending on the change of the alignment state, but for the sake of simplicity, the liquid crystal capacitance 125 was considered as the maximum value. That is, when the capacitance value of the liquid crystal capacitance 125 is calculated, the larger value of the relative dielectric constants of the liquid crystal molecules axis is taken as the relative dielectric constant of the liquid crystal molecule axis and the vertical direction. Was decided to be used. In this example, the control electrode voltage coefficient was changed by changing the capacitance value of the coupling capacitance 126. Coupling capacity 1
Since 26 is formed in the overlapping portion of the pixel electrode 71 and the control electrode 73, the capacitance value of the coupling capacitance 126 depends on the area of the overlapping portion, the film thickness of the interlayer film between the electrodes 71 and 73, and the relative dielectric constant. However, here, an example is shown in which the area of the overlapping portion of the control electrode 73 and the pixel electrode 71 is changed as shown in Table 1 below. The interlayer film between the electrodes 71 and 73 was made of silicon nitride having a thickness of about 200 nm formed by CVD. The relative dielectric constant of the silicon nitride film is about 6.4.

[0116]

[Table 1]

Next, as shown in Table 1, the TFT-LCD (Liquid Cry) in which the control electrode voltage coefficient is changed.
The display device was manufactured, and the display device was observed by a microscope and visually. Each value of the control electrode voltage coefficient of Table 1, 1.1, 1.2, 1.3, and 1.
31, 32, 33 and 34 are micrographs of pixels corresponding to each of Nos. 4 and 4 at the time of display. Figure 3
As is clear from FIGS. 1 to 34, multi-domain liquid crystal alignment control based on the principle of the present invention could be realized in each TFT-LCD having different control electrode voltage coefficients. In particular, when the control electrode voltage coefficient is 1.2 or more, more preferably 1.3 or more, more accurate orientation control can be realized. On the other hand, in the TFT-LCD having a small control electrode voltage coefficient of 1.1,
A slight roughness was observed by visual observation. As is clear from the above results, regarding the control electrode voltage coefficient,
The larger the value, the better the orientation controllability, but the voltage applied to the pixel electrode relatively decreases accordingly. Therefore, the control electrode voltage coefficient becomes too large in terms of driving voltage or brightness. Is not desirable. Considering these things, it is considered that the control electrode voltage coefficient is most preferably about 1.3.

As described above, also with the configuration of this example, it is possible to obtain substantially the same effects as those described in the first embodiment.

Eighth Embodiment In the eighth embodiment of the present invention, FIG. 23 shown in the sixth embodiment is used.
Based on the application example of (w), experimental liquid crystal cells having different wind numbers in which the sizes of the minute alignment regions were made were manufactured and comparatively examined. Here, the minute alignment region means the control electrode 73, the end of the pixel electrode 71, and the opening 7 provided in the pixel electrode 71.
A region divided by boundaries such as 4 is shown, and a region in which the liquid crystal has a substantially single orientation is shown. In the application example of FIG. 23 (w) in this example, the size of one fine alignment region is approximately 40 μm square. On the basis of this, an experimental liquid crystal cell having a minute alignment region size of about 20 μm square was manufactured. As a comparative example, the size of the minute alignment region is about 40μ.
An experimental liquid crystal cell of m square was also manufactured. In these experimental liquid crystal cells, the TFT, the gate bus line, the drain bus line, and the like are omitted, and the structure is such that a voltage can be directly applied to each of the control electrode 73 and the pixel electrode 72.

FIG. 35 is a photomicrograph of the experimental liquid crystal cell of this example after the voltage was switched from the dark state to the bright state. FIG. 35 (a) is a photograph showing a state after switching the voltage from the dark state to the bright state and leaving it for 20 ms, and FIG. 35 (b) is after leaving the voltage for 1 second or more after switching the voltage from the dark state to the bright state. Is a photograph showing the situation. As is clear from comparison of both photographs, in this example, an alignment state almost equal to the steady state alignment state was obtained within 20 ms after voltage application, and the alignment stability and electro-optical response characteristics were excellent. I understood it. The specific measurement values of the response time were dark → light about 15 ms, and light → dark about 9 ms.

On the other hand, FIG. 36 shows a photomicrograph after switching the voltage from the dark state to the bright state in the comparative example. 36 (a) is a photograph showing a state after switching the voltage from the dark state to the bright state and leaving it for 20 ms, FIG.
(B) is a photograph showing a state after switching the voltage from the dark state to the bright state and leaving it for 1 second or more. As is clear from comparison between the two photographs, it was found that in Comparative Example, it took some time until a bright steady state alignment state was obtained after voltage application. The specific measured response time is dark →
Light was about 140 ms, and light → dark was about 9 ms.

As described above, in this example, with respect to the electro-optical response characteristic, the size of the fine alignment region is reduced (20
(μm square) increases the size of the fine alignment region (4
It was confirmed to be superior to the case of 0 μm square). However, regarding the light transmittance of the entire device, it was found that it is preferable that the size of the minute region orientation region is large, due to the difference in the density of dark lines seen at the boundaries of each minute region. That is, the size of the fine alignment region is increased (40 μm).
The size of the micro alignment region is smaller (2 m)
It was confirmed that the light transmittance of the entire experimental liquid crystal cell was higher than that in the case of 0 μm square).

For the reasons described above, the size of the minute alignment region can be appropriately selected depending on the application such as whether or not to display a moving image, and in consideration of the balance with the target pixel pitch of the TFT-LCD. When a moving image is displayed, it is preferably about 20 μm square or less, and when not displaying a moving image, it is preferably about 40 μm square or more. Of course, depending on the application, it may be set in the range of 20 μm to 40 μm square.

As described above, also with the configuration of this example, substantially the same effects as those described in the first embodiment can be obtained.

38. Ninth Embodiment FIG. 37 is a schematic plan view showing a pixel configuration of a multi-domain liquid crystal display device according to a ninth embodiment of the present invention.
39 is a schematic partial sectional view taken along the line HH ′ in FIG.
FIG. 38 is a schematic partial cross-sectional view taken along the line II ′ of FIG. 37.
The structure of the multi-domain liquid crystal display device of this example is greatly different from the structure of the first embodiment described above in that the control electrode is formed integrally with the source terminal of the TFT as a switching element. That is, in the multi-domain liquid crystal display device of this example, as shown in FIGS. 37 to 39, the control electrode 73 is formed integrally with the source terminal 57 of the TFT 54 by an opaque metal such as chrome.
With this configuration, as described above, the coupling capacitance 1
When the capacitance value of 26 is formed to be large, it is feared that the aperture ratio may be lowered, but in this example, the configuration is such that a sufficient aperture ratio can be secured in consideration of this point.
Specifically, the coupling capacitance electrode 171 is formed below the control electrode 73 through the gate insulating film 61, and the pixel formed above the control capacitance 73 through the coupling capacitance electrode 171 and the interlayer insulating film 63. The electrode 71 and the control electrode 73 have overlapping portions, and are connected to each other through a contact hole 172. In FIG. 37, it is difficult to understand because most of the coupling capacitance electrode 171 is hidden under the control electrode 73, but as is clear from FIG. 39, the coupling capacitance electrode 171 is formed along the shape of the control electrode 73. It is located on the lower side.

According to this example, since the coupling capacitance 126 can be formed on both upper and lower sides of the control electrode 73, it is sufficient to increase the capacitance value of the coupling capacitance 126 without increasing the area of the control electrode 73. It is possible to secure a high aperture ratio. In this example, the example in which the control electrode 73 is formed in the lower layer than the pixel electrode 71 is shown, but conversely, the pixel electrode 71 can be formed in the lower layer in the control electrode 73.
By connecting the coupling capacitance electrode 171 disposed on the lower layer of 1 and the control electrode 73 on the upper layer through the contact hole 172, the coupling capacitance can be formed on both upper and lower sides of the pixel electrode 71.

Furthermore, according to this example, the additional capacitance 127
As for the above, a configuration for obtaining a sufficient capacitance value with a small overlapping area is adopted. That is, in the contact hole 177, the additional capacitance terminal 175 and the pixel electrode 71 connected to the common capacitance line 72 by the connection terminal 176.
The additional capacitance 127 is formed by the overlapping portion of Here, the common capacitance line 72 is formed of a metal film in the same layer as the gate bus line 55, and the additional capacitance terminal 175 is formed of a metal film in the same layer as the drain bus line 56. Since the additional capacitance terminal 175 is thus formed in a layer closer to the pixel electrode 71 than the common capacitance line 72, a sufficient capacitance value of the additional capacitance 127 can be secured with a small overlapping area.

In this example, the additional capacitor 127 is formed via the interlayer insulating film 63, but the gate insulating film 61 is used.
Even in the case where the additional capacitance 127 is formed via the above, it is easier to secure a larger capacitance value than the configuration in which the additional capacitance 127 is formed via these two insulating films 63 and 61. In order to obtain a sufficient capacitance value and secure an aperture ratio with a small overlapping area, in addition to the device in the layer structure as described above, for example, the film thickness of the gate insulating film 61 or the interlayer insulating film 63 is reduced. It is also effective in increasing the dielectric constant.

In addition to the above-mentioned effect of ensuring the aperture ratio, in this example, the control electrode 73 is made of a metal film, so that the patterning accuracy of the control electrode 73 can be improved. The reason for this is usually
This is because the accuracy of wet etching is higher with an opaque metal such as Cr than with a transparent electrode such as ITO. In the multi-domain liquid crystal display device of the present invention, since the capacitance value of each capacitor formed in the overlapping portion of each electrode is an important design parameter, it is important to improve the patterning accuracy of each electrode that determines the area of the overlapping portion. Is.

41 to 43, a method of manufacturing the multi-domain liquid crystal display device of this example will be described in the order of steps. First, as shown in FIG. 41A, after chromium is sputter-deposited on the first substrate 11 made of glass, the chromium is patterned by wet etching using a photolithography technique, and the gate bus line 55, Common capacitance line 72 and coupling capacitance electrode 17
1 was formed. Then, as shown in FIG. 41 (b), C
A silicon nitride film was formed by using the VD method to uniformly form the gate insulating film 61. The gate insulating film 61 may be, for example, silicon dioxide, or may be a laminated film of silicon nitride and silicon oxide. Of course, an organic film or the like may be used. Next, an amorphous silicon layer is formed by the CVD method, and is patterned by dry etching using the photolithography technique to form an island-shaped T layer.
An active layer 64 of FT54 was formed.

Next, as shown in FIG. 42C, after chromium is sputter-deposited, patterning is performed by wet etching using the photolithography technique, and the drain bus line 56, drain terminal 58, source terminal 57, The control electrode 73 and the additional capacitance terminal 175 are formed. continue,
As shown in FIG. 42D, a silicon nitride film is formed by CVD to integrally and uniformly form the interlayer insulating film 63, and further, the interlayer insulating film 63 and the gate insulating film 63 are dry-etched by using a photolithography technique. 61 was continuously patterned to form contact holes 172 and 177. Subsequently, as shown in FIG. 43, ITO was sputter-deposited and patterned by wet etching using a photolithography technique to form a floating pixel electrode 71 and a connection terminal 176. In the process of forming the pixel electrode 71 and the connection terminal 176, IT
Patterning accuracy can be improved by patterning O by dry etching instead of wet etching.

As described above, the first substrate 11 is formed by the 5PR process using the photolithography technique a total of 5 times.
To form. Although not described in detail, in the multi-domain liquid crystal display device of the present invention, all peripheral elements such as a gate bus line terminal, a drain bus line terminal, a common capacitance line connecting portion, and an electrostatic protection transistor, which are provided around the display area, are provided. As for the above, it is possible to simultaneously form the above steps in parallel without adding any process. For details of this, for example, Japanese Patent Laid-Open No. 10-23
No. 2409, etc. Other processes such as the manufacturing process of the second substrate 12 and the bonding process of the first substrate 11 and the second substrate 12 can be performed according to the manufacturing method of the first embodiment. .

As described above, also with the configuration of this example, it is possible to obtain substantially the same effects as those described in the first embodiment.

10th Embodiment FIG. 44 is a schematic plan view showing the structure of a pixel of a multi-domain liquid crystal display device according to a 10th embodiment of the present invention.
5 is a schematic partial sectional view taken along the line KK 'in FIG.
6 is a schematic partial cross-sectional view taken along line LL ′ of FIG. 44. The configuration of the multi-domain liquid crystal display device of this example is largely different from the configuration of the first embodiment described above, in that a discharge TFT is arranged on the gate bus line corresponding to the preceding stage of the pixel of interest. Is. That is, the multi-domain liquid crystal display device of this example is shown in FIGS.
15, in the modification of the third embodiment particularly described with reference to FIG. 15, the discharging TFT 141 is arranged in the gate bus line 55 corresponding to the preceding stage of the pixel of interest. Here, the gate terminal, the drain terminal, the source terminal, the active layer, and the like that configure the TFT 141 can be formed in parallel with the display TFT 54 at the same time. T
The drain terminal of the FT 141 has a contact hole 1
42 to the common capacitance line 72, and the source terminal through the contact hole 143.
Connected to 1. With this configuration, the common capacitance line 72 is provided at the moment when the previous-stage gate bus line 55 is selected.
By writing the potential of 2 to the pixel electrode 71, the electric charge accumulated in the pixel electrode 71 can be discharged.

Further, in this example, in the opening 74 provided in the pixel electrode 71, a portion corresponding to the opening 74 on which the control electric field from the control electrode 73 arranged in the lower layer acts, is the interlayer insulating film. The configuration is such that 63 is removed. With such a structure, there is no loss of voltage in the insulating film portion between the control electrode 73 and the liquid crystal layer, and the electric field from the control electrode 73 is directly applied to the liquid crystal layer. Further, since the concave shape formed by removing the interlayer insulating film 63 matches the tilt direction of the liquid crystal molecules due to the action of the tilt electric field, the effect that the alignment of the liquid crystal at the boundary of the fine alignment region is stabilized can be obtained. . Since the removal of the interlayer insulating film 63 can be performed in parallel with the step of exposing the terminal portion around the display region,
No additional steps are required.

As described above, also with the configuration of this example, it is possible to obtain substantially the same effects as those described in the first embodiment.

Although the embodiment of the present invention has been described in detail above with reference to the drawings, the specific structure is not limited to this embodiment, and there are design changes and the like within a range not departing from the gist of the present invention. Also included in the present invention. For example, although an example in which a TFT is used as an element that operates as a switching element has been described, the present invention is not limited to this, and MIM (Metal
A diode such as an insulator metal element may be used. In addition, although an example in which ITO is used as the transparent electrode forming the pixel electrode and the control electrode has been described,
Not limited to this, it is also possible to use other materials such as a Nesa film (tin oxide film). Further, when the control electrode is composed of a transparent electrode, the transparent electrode may be used only partially. Further, although the example in which chromium is used as the metal composing the gate bus line, the source terminal, the drain terminal, etc. has been described, the present invention is not limited to this, and other materials such as molybdenum, tantalum or alloys thereof can be used. Is.

[0138]

As described above, according to the present invention, the control electrode provided for each pixel is driven by the switching element provided for each pixel, so that the pixel displays bright or dark. Alternatively, even in the case of intermediate display, the control electrode potential is controlled accordingly, so that the domain formation of the liquid crystal can be surely controlled by the oblique electric field generated so as to spread from the control electrode. Further, since the divided voltage of the control electrode voltage is applied to the pixel electrode via the coupling capacitance, 1
2 control electrodes and pixel electrodes with only one switching element
One electrode potential can be controlled. Therefore, the number of complicated processes such as the microfabrication process of the common electrode is increased,
It is possible to provide a multi-domain liquid crystal display device having high contrast and excellent viewing angle characteristics without requiring advanced bonding technology.

[Brief description of drawings]

FIG. 1 is a schematic plan view showing a pixel configuration of a multi-domain liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a schematic partial cross-sectional view taken along the line AA ′ in FIG.

FIG. 3 is a schematic partial cross-sectional view taken along the line BB ′ of FIG.

FIG. 4 is a schematic partial cross-sectional view taken along the line CC ′ in FIG.

FIG. 5 is an equivalent circuit diagram of a pixel of the multi-domain liquid crystal display device.

FIG. 6 is a process chart showing a method of manufacturing the multi-domain liquid crystal display device in the order of steps.

FIG. 7 is a process chart showing the method of manufacturing the multi-domain liquid crystal display device in the order of steps.

FIG. 8 is a schematic plan view showing a pixel configuration of a multi-domain liquid crystal display device according to a second embodiment of the present invention.

9 is a schematic partial cross-sectional view taken along the line DD ′ of FIG.

10 is a schematic partial cross-sectional view taken along line EE ′ of FIG.

FIG. 11 is a diagram schematically showing multi-domain liquid crystal alignment in the same multi-domain liquid crystal display device.

FIG. 12 is a diagram schematically showing a state of transmitted light corresponding to a multi-domain alignment state in the same multi-domain liquid crystal display device.

FIG. 13 is a schematic partial cross-sectional view showing the structure of a multi-domain liquid crystal display device which is a third embodiment of the present invention.

FIG. 14 is an equivalent circuit diagram of a pixel of the multi-domain liquid crystal display device.

FIG. 15 is an equivalent circuit diagram of a pixel of a modified example of the multi-domain liquid crystal display device.

FIG. 16 is a schematic partial sectional view showing the structure of a multi-domain liquid crystal display device which is a fourth embodiment of the present invention.

FIG. 17 is a schematic plan view showing a pixel configuration of a multi-domain liquid crystal display device which is a fifth embodiment of the present invention.

FIG. 18 is a schematic partial cross-sectional view taken along the line FF ′ in FIG.

19 is a schematic partial cross-sectional view taken along line GG ′ of FIG.

FIG. 20 is a diagram showing a planar shape of a combination example of a pixel electrode and a control electrode of a multi-domain liquid crystal display device which is a sixth embodiment of the present invention.

FIG. 21 is a diagram showing a planar shape of a basic configuration in an example of a combination of pixel electrodes and control electrodes of the same multi-domain liquid crystal display device.

FIG. 22 is a diagram showing a planar shape of a basic configuration in an example of a combination of pixel electrodes and control electrodes of the same multi-domain liquid crystal display device.

FIG. 23 is a diagram showing a planar shape of an example in which the same basic configuration is applied to the same multi-domain liquid crystal display device.

FIG. 24 is a micrograph showing an alignment state of pixels of the multi-domain liquid crystal display device.

FIG. 25 is a micrograph showing an alignment state of pixels of the multi-domain liquid crystal display device.

FIG. 26 is a micrograph showing an alignment state of pixels of the multi-domain liquid crystal display device.

FIG. 27 is a micrograph showing an alignment state of pixels of the multi-domain liquid crystal display device.

FIG. 28 is a micrograph showing an alignment state of pixels of the multi-domain liquid crystal display device.

FIG. 29 is a micrograph showing an alignment state of pixels of the multi-domain liquid crystal display device.

FIG. 30 is a micrograph showing an alignment state of pixels of the multi-domain liquid crystal display device.

FIG. 31 is a micrograph of a pixel at the time of display of the multi-domain liquid crystal display device which is the seventh embodiment of the present invention.

FIG. 32 is a micrograph of a pixel at the time of displaying by the multi-domain liquid crystal display device.

FIG. 33 is a micrograph of a pixel at the time of displaying by the multi-domain liquid crystal display device.

FIG. 34 is a micrograph of a pixel at the time of display of the multi-domain liquid crystal display device.

FIG. 35 is a micrograph of the experimental liquid crystal cell of the multi-domain liquid crystal display device according to the eighth embodiment of the present invention after the voltage is switched from the dark state to the bright state.

FIG. 36 is a micrograph of a comparative liquid crystal cell of the same multi-domain liquid crystal display device after switching the voltage from a dark state to a bright state.

FIG. 37 is a schematic plan view showing a pixel configuration of a multi-domain liquid crystal display device which is a ninth embodiment of the present invention.

FIG. 38 is a schematic partial cross-sectional view taken along the line HH ′ of FIG. 37.

FIG. 39 is a schematic partial cross-sectional view taken along the line II ′ of FIG. 37.

FIG. 40 is a schematic partial cross-sectional view taken along the line JJ ′ of FIG. 37.

FIG. 41 is a process drawing showing the manufacturing method of the multi-domain liquid crystal display device in the order of processes.

FIG. 42 is a process chart showing the method of manufacturing the multi-domain liquid crystal display device in the order of steps.

FIG. 43 is a process drawing showing the manufacturing method of the multi-domain liquid crystal display device in the order of processes.

FIG. 44 is a schematic plan view showing a pixel configuration of a multi-domain liquid crystal display device which is a tenth embodiment of the present invention.

45 is a schematic partial cross-sectional view taken along the line KK ′ of FIG. 44.

FIG. 46 is a schematic partial cross-sectional view taken along line LL ′ of FIG. 45.

FIG. 47 is a schematic partial cross-sectional view showing the configuration of a pixel of a conventional multi-domain liquid crystal display device.

[Explanation of symbols]

11 First Substrate 12 Second Substrate 20 Liquid Crystal 21 Liquid Crystal Molecules 54 TFT (Switching Element) 55 Gate Bus Line 56 Drain Bus Line 57 Source Terminal 58 Drain Terminals 59, 142, 143, 149, 172, 177
Contact hole 61 Gate insulating film 62 Semiconductor film 63 Interlayer insulating film 64 Active layer (semiconductor layer) 65 TFT protective film 71 Pixel electrode 72 Common capacitance line 73 Control electrode 74 Opening 75 Capacitance terminal 76 Opening or pixel electrode end 81 Common electrode 91 Color layer 92 Overcoat layer 93 Light shielding layer 125 Liquid crystal capacitance 126 Coupling capacitance 127 Additional capacitance 135 Coupling resistance 141 TFT (Discharging element) 171 Coupling capacitance electrode 175 Additional capacitance terminal 176 Connection terminal E1 Liquid crystal driving electric field

─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Hiroshi Hayama 5-7-1, Shiba, Minato-ku, Tokyo NEC Corporation (72) Inventor Hiroshi Kano 5-7-1, Shiba, Minato-ku, Tokyo NEC Co., Ltd. (72) Inventor Naoyasu Ikeda 5-7 Shiba 5-7, Minato-ku, Tokyo NEC Corporation (72) Inventor Kenichi Takatori 5-7-1 Shiba, Minato-ku, Tokyo NEC Corporation (72) Inventor Takashi Nose, 5-7-1, Shiba, Minato-ku, Tokyo, NEC Corporation (72) Takahiko Watanabe, 5-7-1, Shiba, Minato-ku, Tokyo, NEC Corporation (56) Reference Documents JP-A-4-348323 (JP, A) JP-A-57-32484 (JP, A) JP-A-10-333180 (JP, A) JP-A-8-179278 (JP, A) JP-A-3- 141325 (JP, A) JP 10-90708 (JP , A) JP-A-6-43461 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G02F 1/1337 G02F 1/1333 G02F 1/1343 G02F 1/1362

Claims (43)

(57) [Claims] 1. A liquid crystal sandwiched between a pair of substrates, a plurality of gate bus lines extending in the lateral direction and formed on one side of the substrates, and a plurality of drain bus lines extending in the vertical direction, A plurality of pixels are arranged in a matrix corresponding to each intersection of the gate bus line and the drain bus line, and each pixel has a switching element, a pixel electrode, and an oblique direction with respect to the liquid crystal. A control electrode for generating an electric field to form a plurality of alignment regions in one pixel is provided, and a common electrode is provided on the other side of the substrate.
A multi-domain liquid crystal display device comprising a pole , wherein the control electrode is connected to one terminal of the switching element, the pixel electrode has a coupling capacitance with the control electrode, When a corresponding gate bus line is selected, a signal voltage is applied from the corresponding drain bus line via the corresponding switching element, and the signal voltage is divided into the pixel electrodes via the coupling capacitance. by but which is configured to be applied, the voltage applied to the control electrode applied of the pixel electrode
The absolute value is larger than the voltage
Generate an oblique electric field so that it spreads outward from the control electrode.
Therefore, a multi-domain liquid crystal display device is characterized in that a plurality of alignment regions are formed in one pixel . 2. The multi-domain liquid crystal display device according to claim 1, wherein the pixel electrode and the control electrode are configured such that the pixel electrode is a lower layer via an insulating film. 3. The multi-domain liquid crystal display device according to claim 1, wherein an opening is formed in the pixel electrode. 4. The multi-domain liquid crystal display device according to claim 3, wherein the control electrode causes an electric field to control an alignment state of the liquid crystal from the opening. 5. The multi-domain liquid crystal display device according to claim 1, further comprising a common capacitance line for adding capacitance to the pixel electrode. 6. The multi-domain liquid crystal display device according to claim 5, wherein the common capacitance line is arranged at a position corresponding to the opening. 7. The multi-domain liquid crystal display device according to claim 5, further comprising an additional capacitance having a predetermined capacitance between the pixel electrode and the common capacitance line. 8. The multi-domain liquid crystal display device according to claim 1, wherein at least a part of the control electrode is a transparent electrode. 9. The multi-domain liquid crystal display device according to claim 1, wherein quarter-wave plates are arranged on both sides of the liquid crystal, respectively. 10. The quarter-wave plate is provided on both sides of the liquid crystal, and the optical axes of the quarter-wave plate are arranged so as to be orthogonal to each other. 1
The multi-domain liquid crystal display device described. 11. The switching element is a TFT having a bottom-gate structure.
2. The multi-domain liquid crystal display device according to any one of 1. 12. The switching device according to claim 1, wherein the switching device is a TFT having a top gate structure.
2. The multi-domain liquid crystal display device according to any one of 1. 13. The multi-domain liquid crystal display device according to claim 11, wherein the insulating film is formed integrally with an insulating film that protects the TFT. 14. The control electrode is integrally formed with a source terminal of the TFT.
14. The multi-domain liquid crystal display device according to 2 or 13. 15. The multi-domain liquid crystal display device according to claim 3, wherein the opening is formed in a window shape. 16. The multi-domain liquid crystal display device according to claim 3, wherein the opening is formed so as to make a cut from one side or both sides of the pixel electrode. 17. The multi-domain liquid crystal display according to claim 1, further comprising a resistance element between the pixel electrode and the control electrode, the resistance element discharging electric charge accumulated in the pixel electrode. apparatus. 18. The multi-domain liquid crystal display device according to claim 17, wherein the resistance element has a substantially finite resistance value. 19. The multi-domain liquid crystal display device according to claim 5, further comprising a resistance element having a substantially finite resistance value between the pixel electrode and the common capacitance line. 20. The multi-domain liquid crystal display device according to claim 1, wherein the operation mode of the liquid crystal is a TN mode in which a liquid crystal having a positive dielectric anisotropy is twist-aligned. 21. The multi-domain liquid crystal display device according to claim 20, wherein the liquid crystal has a spontaneous chiral property . 22. The multi-domain liquid crystal display device according to claim 20, wherein the liquid crystal is non-spontaneous chiral . 23. The multi-domain liquid crystal display device according to claim 1, wherein the operation mode of the liquid crystal is a homogeneous mode in which liquid crystal having positive dielectric anisotropy is uniformly aligned. 24. The multi-domain liquid crystal display device according to claim 1, wherein an operation mode of the liquid crystal is a VA mode in which a liquid crystal having a negative dielectric anisotropy is homeotropically (vertically) aligned. 25. The pixel electrode is formed of a plurality of minute pixel electrodes each having a quadrangular shape, a control electrode is arranged along one side of the quadrangle, and the remaining three sides are an opening or a pixel electrode end. Claim 1, characterized in that
2. The multi-domain liquid crystal display device according to 2 or 3. 26. The pixel electrode is formed of a plurality of minute pixel electrodes each having a quadrangle, control electrodes are arranged along two sides of the quadrangle, and the remaining two sides are an opening or a pixel electrode end. Claim 1, characterized in that
2. The multi-domain liquid crystal display device according to 2 or 3. 27. The multi-domain liquid crystal display device according to claim 25, wherein the quadrangle is a substantially square shape. 28. The pixel electrode is formed of a plurality of minute pixel electrodes each having a triangular shape, control electrodes are arranged along two sides of the triangle, and the remaining one side is an opening or a pixel electrode end. 4. The multi-domain liquid crystal display device according to claim 1, wherein the multi-domain liquid crystal display device is a partial opening. 29. The pixel electrode is formed of a plurality of minute pixel electrodes each having a triangle shape, a control electrode is arranged along one side of the triangle, and the remaining two sides are an opening or a pixel electrode end. 4. The multi-domain liquid crystal display device according to claim 1, wherein the multi-domain liquid crystal display device is a partial opening. 30. The pixel electrode is formed of a plurality of minute pixel electrodes each having a pentagonal shape, control electrodes are arranged along two sides of the pentagonal shape, and the remaining three sides are openings or pixel electrode ends. 4. The multi-domain liquid crystal display device according to claim 1, wherein the multi-domain liquid crystal display device is a partial opening. 31. The pixel electrode is formed of a plurality of minute pixel electrodes, and the minute pixel electrodes are defined by claim 25.
2. The micro pixel electrode according to any one of 0 above is configured by combining two or more kinds.
2. The multi-domain liquid crystal display device according to 2 or 3. As claimed in claim 32 the reference voltage of the common electrode, the ratio of the pixel electrode voltage applied to the pixel electrode of the control electrode voltage applied to the control electrode, 1.1-1.4
28. The multi-domain liquid crystal display device according to claim 27, wherein: 33. The multi-domain liquid crystal display device according to claim 32, wherein a ratio of the control electrode voltage to the pixel electrode voltage is set to 1.2 to 1.4. 34. The multi-domain liquid crystal display device according to claim 33, wherein a ratio of the control electrode voltage to the pixel electrode voltage is set to about 1.3. 35. The liquid crystal display device according to claim 27, wherein the size of the fine alignment region in which the liquid crystal has a substantially single alignment is about 20 μm square or less. 36. The liquid crystal display device according to claim 27, wherein the size of the fine alignment region in which the liquid crystal has a substantially single alignment is approximately 40 μm square or more. 37. The liquid crystal display device according to claim 27, wherein the size of the fine alignment region in which the liquid crystal has a substantially single alignment is 20 to 40 μm 2. 38. A coupling capacitance terminal electrically connected to one of the pixel electrode and the control electrode and another electrode not connected to the coupling capacitance terminal are overlapped with each other through a gate insulating film. 13. The multi-domain liquid crystal display device according to claim 11 or 12, wherein at least a part of the coupling capacitance is constituted by the above. 39. An additional capacitance terminal electrically connected to either the pixel electrode or the common capacitance line,
8. At least a part of the additional capacitance is formed by superimposing the other one of the additional capacitance terminals not connected via a protective insulating film.
The multi-domain liquid crystal display device described. 40. An additional capacitance terminal electrically connected to either one of the pixel electrode and the common capacitance line,
8. The multi-domain liquid crystal display device according to claim 7, wherein at least a part of the additional capacitance is configured by superimposing the other one of the additional capacitance terminals which is not connected via a gate insulating film. 41. A discharge element for discharging an electric charge accumulated in the pixel electrode is arranged on a gate bus line corresponding to a preceding stage of an arbitrary pixel.
The multi-domain liquid crystal display device described. 42. The protective insulating film is removed from a portion of the opening provided in the pixel electrode, the portion corresponding to the opening on which the control electric field from the control electrode arranged in the lower layer acts. Item 41. The multi-domain liquid crystal display device according to item 41. 43. A liquid crystal sandwiched between a pair of substrates, and a plurality of pixels arranged in a matrix on one side of the substrates, each pixel having a switching element, a pixel electrode, and A control electrode for generating an electric field in an oblique direction with respect to the liquid crystal to form a plurality of alignment regions in one pixel, and a common electrode on the other side of the substrate.
In the multi-domain liquid crystal display device, the control electrode is connected to one terminal of the switching element, the pixel electrode has a coupling capacitance with the control electrode, and the control electrode corresponds to the control electrode. wherein the signal through the switching element voltage is applied, is the pixel electrode is configured to the partial pressure of the signal voltage through the coupling capacitor is applied to
The voltage applied to the control electrode is applied to the pixel electrode.
The absolute value is larger than the voltage
Generate an oblique electric field so that it spreads outward from the control electrode.
Therefore, a multi-domain liquid crystal display device is characterized in that a plurality of alignment regions are formed in one pixel .