JPH1138444A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a ferroelectric or antiferroelectric liquid crystal display device where a display performance is controlled after manufacture by having a dielectric layer having different electric capacities at an area between a first picture element electrode and a counter electrode and the area between a second picture element electrode and the counter electrode. SOLUTION: Since one picture element is constituted of picture element electrodes 9 and 10 and the thickness of oriented films 22 and 23 differs each other on the picture element electrodes 9 and 10, a different display performance is obtained by independently switching the picture element electrodes 9 and 10. Thus, in the case of switching only the picture element electrode 9, high contrast suitable for a monitor display is obtained because the areas of the oriented films 22 and 23 on the picture element electrode 9 are formed to be thin. Also, in the case of switching only the picture element electrode 10, high speed responsiveness suitable for a moving picture display is obtained because the areas of the alignment layers 22 and 23 on the picture element electrode 9 are formed to be thick.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal display, and more particularly to a liquid crystal display using a smectic liquid crystal material having a large spontaneous polarization such as a ferroelectric liquid crystal material or an antiferroelectric liquid crystal material.

[0002]

2. Description of the Related Art Ferroelectric liquid crystal materials and antiferroelectric liquid crystal materials are smectic liquid crystal materials having a large spontaneous polarization. A liquid crystal display device using such a liquid crystal material is expected to be a next-generation liquid crystal display device because it can obtain a fast response speed and a wide viewing angle by being driven in a surface stabilized display mode. Moving image display by driving using an active matrix has been attempted.

However, since these liquid crystal materials having a large spontaneous polarization have a very high dielectric constant of several tens to several thousands, an alignment film which does not pose a problem in a liquid crystal display device using a nematic liquid crystal material. It has been found that variations in the thickness of the device greatly affect the display performance of the device.
The reason will be described below.

A liquid crystal display device has a pixel electrode formed on a substrate, a counter electrode provided to face the pixel electrode, and a liquid crystal layer provided between the pixel electrode and the counter electrode. . When a predetermined voltage is applied between the pixel electrode and the counter electrode of such a liquid crystal display device, an electric field corresponding to the applied voltage is formed in the liquid crystal layer.

However, since a liquid crystal display device is generally provided with an alignment film and an insulating film on the surface of a pixel electrode and a counter electrode, the voltage applied between the electrodes is applied only to the liquid crystal layer. Instead, the pressure is divided by all members provided between the pixel electrode and the counter electrode, such as an alignment film and an insulating film. Therefore, variations in the thickness of members such as an alignment film and an insulating film affect the electric field formed in the liquid crystal layer and cause variations in contrast.

Further, it is considered that the alignment film or the insulating film provided between the electrodes functions as a capacitor connected in series with the liquid crystal layer. The variation in the capacitance of this capacitor is
When the liquid crystal display device is driven by inverting the orientation of the liquid crystal material for each frame (hereinafter referred to as AC driving), the contrast is affected, and writing is performed over a plurality of frames without inverting the orientation of the liquid crystal material. When driving (hereinafter, referred to as DC driving), the response speed and the contrast are affected.

[0007] In the liquid crystal display device using a nematic liquid crystal material, the thickness variation of the alignment film and the insulating film is about 1/50 of the thickness of the liquid crystal layer. Since the nematic liquid crystal material and the organic polymer material used for the alignment film and the inorganic oxide material used for the insulating film have almost the same dielectric constant, the display performance is hardly affected.

However, in a ferroelectric or antiferroelectric liquid crystal display using a smectic liquid crystal material having a large dielectric constant, a slight variation in the thickness of an alignment film, an insulating film or the like has a great effect on the display performance of the element. To give.

[0009] Such influence on display performance can be reduced by using only a substrate on which an alignment film or the like having a uniform thickness is formed, but the problem is that the yield is reduced and the manufacturing cost is increased. Is generated. Also, the alignment film and the like,
It is very difficult to form with a uniform thickness and a high yield. Therefore, there is a need for a ferroelectric liquid crystal display device capable of controlling display performance after manufacturing even when an alignment film or an insulating film having an uneven thickness is formed.

In the case of direct current drive, the response speed and contrast of a ferroelectric or antiferroelectric liquid crystal display device can be controlled by changing the thickness of the alignment film. However, since there is a trade-off between the response speed and the contrast, it is difficult to simultaneously obtain a high response speed and a high contrast.

Therefore, in the manufacture of a DC-driven ferroelectric or antiferroelectric liquid crystal display device, the thickness of the alignment film and the thickness of the insulating film are changed depending on whether a moving image is displayed or a monitor is used. There is a need. That is,
For moving image display specifications that require a fast response speed, the alignment film and insulating film must be formed thick, and for high-contrast monitor specifications that do not require high-speed response, the alignment film and insulating film must be formed thin. It is.

However, when a ferroelectric or antiferroelectric liquid crystal display device is manufactured according to the respective specifications as described above, the purpose of use is limited to monitor use or moving image display. Therefore, there is a need for a ferroelectric or antiferroelectric liquid crystal device that can be used for both a monitor and a moving image display by controlling the display performance after manufacturing with the same panel.

[0013]

SUMMARY OF THE INVENTION An object of the present invention is to provide a ferroelectric or antiferroelectric liquid crystal display device capable of controlling display performance after manufacturing.

[0014]

According to the present invention, there are provided: a) a first switching element, a second switching element sharing a signal electrode line with the first switching element, and a source of the first switching element. A first pixel electrode electrically connected to the electrode, a second pixel electrode provided in parallel with the first pixel electrode, and electrically connected to a source electrode of the second switching element; A) a first substrate having a counter electrode on the surface of the first substrate on which the first and second pixel electrodes are formed, and c) a second substrate having a counter electrode on the opposite surface of the first substrate. Provided between the first substrate and the second substrate,
A liquid crystal layer containing a ferroelectric or antiferroelectric liquid crystal material; and d) a region provided between the first and second pixel electrodes and the counter electrode, between the first pixel electrode and the counter electrode. And a region between the second pixel electrode and the counter electrode, and a dielectric layer having a different electric capacitance.

The present invention also provides: a) a first element having a switching element and a pixel electrode electrically connected to a source electrode of the switching element.
B) a counter electrode, an insulating layer provided on the counter electrode, and a conductive layer provided at a predetermined position on the insulating layer, wherein a pixel electrode of the first substrate is formed. A second substrate disposed opposite to the surface provided; c) provided between the first substrate and the second substrate;
A liquid crystal layer containing a ferroelectric or antiferroelectric liquid crystal material; d) an alignment film provided on at least one of the first substrate and the second substrate in contact with the liquid crystal layer; and e) the switching element. And a light blocking portion provided between the conductive layer and the conductive layer, wherein the conductive layer is provided corresponding to the pixel electrode and the switching element of the first substrate, and the switching element of the counter electrode and the conductive layer is provided. A liquid crystal display device characterized in that the opposite electrode and the conductive layer are electrically connected by irradiating a portion corresponding to (a) with laser light. The present invention is characterized in that in the above liquid crystal display device, the light blocking portion is a black matrix.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a liquid crystal display device according to the present invention will be described with reference to the drawings. FIG. 1 shows a cross-sectional view of the liquid crystal display device according to the first embodiment of the present invention. FIG.
In the liquid crystal display device 1, an array substrate 2 serving as a first substrate, a counter substrate 3 serving as a second substrate disposed to face the array substrate 2, and a liquid crystal display device 1 disposed between the array substrate 2 and the counter substrate 3. It is constituted by the liquid crystal layer 4 provided.

In the array substrate 2, first and second switching elements (not shown) are provided on a surface of the substrate 5 facing the counter substrate 3, and the first and second switching elements are provided. First and second pixel electrodes 9, 10 electrically connected to the respective source electrodes are formed,
These form an array substrate 2.

In the counter substrate 3, a black matrix 16, a color filter layer 17, a transparent counter electrode 19, and a transparent insulating layer 18 are sequentially provided on a surface of the transparent substrate 15 facing the array substrate 2.

The liquid crystal layer 4 is made of a ferroelectric liquid crystal material or an antiferroelectric liquid crystal material 20.
A spacer 21 is interposed between the substrate and the counter substrate 3 to keep the distance between them constant.

A polarizing plate 11 and a polarizing plate 14 are provided on the back surfaces of the opposing surfaces of the array substrate 2 and the opposing substrate 3, respectively. On the opposing surfaces of the array substrate 2 and the opposing substrate 3, the first pixel electrode 9 and the second pixel electrode 10
Alignment films 22 and 23 having different thicknesses are formed as dielectric layers. Here, the dielectric layer refers to the alignment films 22 and 23 provided between the pixel electrodes 9 and 10 and the counter electrode 18 except for a conductor such as a metal or a liquid crystal material 20.
And a layer having a dielectric property such as the insulating film 19.

Array substrate 2 of the ferroelectric liquid crystal display device
Will be described with reference to FIGS. 2 and 3. FIG.
3 and 3 are a top view and an equivalent circuit diagram of the array substrate 2, respectively. In FIG. 2, a first switching element 6, a second switching element 7 sharing a signal electrode line 8 with the first switching element 6, and a source electrode of the first switching element 6 are electrically connected to a substrate 5. The first connected to
And a second pixel electrode 10 electrically connected to the source electrode of the second switching element 7.

First and second switching elements 6, 7
Are gate electrode lines 12 and 13 that are driven independently of each other.
And a first pixel electrode 9 and a second pixel electrode 10
Is switched independently of.

As described above, in the liquid crystal display device according to the first embodiment of the present invention, one pixel is constituted by the pixel electrodes 9 and 10, and the thickness of the alignment films 22 and 23 is
Since the pixel electrodes 9 and 10 are different from each other, different display performances can be obtained by switching the pixel electrodes 9 and 10 independently.

That is, when only the pixel electrode 9 is switched, a high contrast suitable for monitor display can be obtained because the regions of the alignment films 22 and 23 on the pixel electrode 9 are formed thin. When only the pixel electrode 10 is switched, since the regions of the alignment films 22 and 23 on the pixel electrode 9 are formed thick, high-speed responsiveness suitable for displaying moving images can be obtained.

When the pixel electrode 9 and the pixel electrode 10 are switched in conjunction with each other, not only can a high contrast suitable for display on a monitor or the like be obtained, but also a high contrast can be obtained.
Light use efficiency can be improved.

As described above, according to the liquid crystal display device according to the first embodiment of the present invention, it is possible to control the display performance of the device by controlling the driving method after manufacturing the device.

As described above, both thicknesses of the alignment films 22 and 23 are
Although the case where the thickness is changed between the pixel electrode 9 and the pixel electrode 10 has been described, the thickness of one of the alignment films 22 and 23 may be changed. The pixel electrodes 9 and 10 and the counter electrode 19
A dielectric layer other than the alignment films 22 and 23 is provided between them, and the display performance of the device can be controlled even if the thickness of the dielectric layer is changed. Further, the same effect can be obtained even if this dielectric layer is formed of materials having different relative dielectric constants in the region between the pixel electrode 9 and the counter electrode 19 and the region between the pixel electrode 10 and the counter electrode 19. it can.

When the electric capacity of the dielectric layer is converted into the thickness of a polyimide film having the same electric capacity, the pixel electrode 9-
The difference between the region between the counter electrode 19 and the region between the pixel electrode 10 and the counter electrode 19 is preferably about 10 nm to 150 nm, more preferably about 30 nm to 50 nm. When such a difference is formed in the capacitance of the dielectric layer, a high contrast and a high response speed can be obtained by driving each of the driving methods.

Next, a liquid crystal display device according to a second embodiment of the present invention will be described with reference to FIG. FIG.
, The liquid crystal display device 31 includes an array substrate 32 as a first substrate, and a second substrate
, And a liquid crystal layer 34 provided between the array substrate 32 and the counter substrate 33.

In the array substrate 32, the opposite substrate 3 of the substrate 5
The switching element 35 is provided on a surface facing the switching element 3, and a pixel electrode 36 electrically connected to a source electrode of the switching element 35 is formed. On this switching element 35, the black matrix 3
7 are formed, and an alignment film 38 is provided on the black matrix 37 and the pixel electrodes 36. That is, the array substrate 32 has a black matrix (BM) on-array structure.

The liquid crystal layer 34 is made of a ferroelectric liquid crystal material or an antiferroelectric liquid crystal material 20, and a spacer is provided between the array substrate 32 and the counter substrate 33 to keep a constant distance therebetween. 21 intervenes.

In the counter substrate 33, the color filter layer 17, the counter electrode 19, the insulating layer 39, the conductive layer 41 patterned in a predetermined pattern, the insulating layer 40, An alignment film 42 is provided sequentially.

The polarizing plate 11 and the polarizing plate 14 are provided on the back surfaces of the respective opposing surfaces of the array substrate 32 and the opposing substrate 33, respectively. The liquid crystal display device 31 immediately after manufacture has a counter electrode 1 as shown by reference numeral 43.
9 and the conductive layer 41 are arranged close to each other, but are electrically insulated. Therefore, in the state shown by reference numeral 43, the conductive layer 41 does not function as a counter electrode.

However, when the opposite electrode 19 and the conductive layer 41 of the liquid crystal display device 31 are irradiated with laser light such as a YAG laser from the substrate 15 side, the opposite electrode 19 and the conductive layer 41 are separated from each other as indicated by reference numeral 44. It is electrically connected, and the conductive layer 41 functions as a counter electrode.

Therefore, by irradiating a predetermined position with a laser beam, the electric capacity of the alignment film and the insulating film located between the pixel electrode 36 and the counter electrode changes, so that compared with before the laser beam irradiation, The same effect as when the thickness of the insulating film or the alignment film is reduced can be obtained.

The case where one conductive layer 41 is laminated on the counter electrode 19 with the insulating layer 39 interposed therebetween has been described. However, a configuration in which a plurality of conductive layers are laminated on the counter electrode 19 with the insulating layer interposed therebetween is described. It may be. When a plurality of conductive layers are stacked in this manner, the electric capacities of the alignment film and the insulating film can be controlled in multiple steps by appropriately controlling the intensity of laser light to be applied.

When a plurality of conductive layers are stacked, if the respective conductive layers are partially shifted, the desired conductive layer can be electrically connected to the counter electrode 19 by controlling the irradiation position of the laser beam. Can be connected.

In order to selectively melt only the opposing electrode 19, the conductive layer 41 and the insulating layer 39 at the position indicated by the reference numeral 43, the opposing electrode 19, the conductive layer 41, Preferably, at least one of the insulating layers 39 is made of a light-absorbing material having a relatively low melting point. When the device has such a configuration, the opposing electrode 19 and the conductive layer 41 can be efficiently conducted, and the alignment film 42, the insulating layer 40, and the like can be prevented from being melted.

In order to prevent an electrical short circuit between the counter electrode 19 and the pixel electrode 36 when the cell gap is narrowed, it is preferable that the insulating layer 40 be formed to have a thickness of 100 nm or more.

The irradiation of the laser beam may damage the switching element 35 formed on the array substrate 32. However, in the ferroelectric liquid crystal display device according to the second embodiment of the present invention, the switching element 35 may be damaged. , Switching element 35
Since the light blocking portion such as the black matrix 37 is provided on the upper side, the laser light is absorbed or reflected by the light blocking portion, and there is no possibility that the switching element 35 is damaged.

This light blocking section does not necessarily need to be provided on the switching element 35. The light blocking part is a transparent substrate 1
The laser beam incident from the fifth side is arranged so as to reach the counter electrode 19 and the conductive layer 41 and not to reach the switching element 35. Therefore, the light blocking section may be arranged, for example, between the conductive layer 41 and the insulating layer 40 so as to prevent laser light from reaching the switching element 35.

The light blocking portion is not particularly limited as long as it blocks laser light, and is made of a light reflecting material or a light absorbing material. Particularly, a black matrix is preferable. When the light shielding portion is made of a black matrix, good display performance can be obtained, and the configuration of the device can be simplified.

The above-described liquid crystal display device 31 has a moving image display specification in which an alignment film or an insulating film is formed thick, or a laser light beam is irradiated after manufacturing to substantially reduce the thickness of the alignment film or the insulating film. , Monitor specification. Further, when there is a variation in display performance in the display surface, the above-described ferroelectric liquid crystal display device 31 can uniformly irradiate the display performance in the surface by selectively irradiating a predetermined position with laser light. Can be

In the liquid crystal display devices according to the first and second embodiments of the present invention described above, a transparent substrate such as glass is used as an array substrate, and a gate electrode line,
A switching element including a signal electrode line, a TFT, and the like, an alignment film, and the like are formed.

As the opposing substrate, a transparent substrate such as glass is used, and a color filter layer is formed on the surface as necessary. The pixel electrode, the counter electrode, and the conductive layer formed on the array substrate and the counter substrate are made of a transparent conductive material such as ITO, and the alignment film is polyimide, polyamide,
Polyvinyl alcohol, polyimide amide, and SiN
And the like, which is used for a general alignment film. The insulating film is made of a transparent insulating inorganic material such as SiO ₂ , Ta ₂ O _5, or the like, and a polarizing plate is provided on each of the array substrate and the counter substrate. As the liquid crystal material forming the liquid crystal layer, a smectic liquid crystal material having a large spontaneous polarization such as a ferroelectric liquid crystal material or an antiferroelectric liquid crystal material is used.

[0046]

Embodiments of the present invention will be described below. These embodiments are described for the purpose of facilitating the understanding of the present invention, and can be variously modified without departing from the gist of the present invention.

Example 1 An antiferroelectric liquid crystal display device shown in FIG. 1 was manufactured as follows. First, FIG.
The array substrate 2 in which two switching elements 6, 7 and pixel electrodes 9, 10 made of ITO are formed on a transparent glass substrate 5 shown in FIG. Was printed to a thickness of 20 nm and baked.

Next, a phenolic resin-based positive resist is applied to the entire surface of the array substrate 2 on which the polyimide film is formed, and the resist film is patterned in a pattern corresponding to the pixel electrode 9 using UV light having a center wavelength of 436 nm. Exposure. The exposed resist was removed using a developer NMD-3 manufactured by Tokyo Ohka Co., Ltd. to expose a polyimide film on the pixel electrode 9, and the exposed polyimide film was removed by etching.

Further, the remaining resist film was removed by using a resist stripper 104 made by Tokyo Ohka Co., Ltd.
Polyimide A was applied to a thickness of 40 nm on the entire surface of the array substrate 2 on which the pixel electrodes 9 and 10 were formed, and baked.
As described above, the thickness on the pixel electrode 9 is 40 nm,
An alignment film 22 having a thickness of 60 nm on the pixel electrode 10 was formed.

Next, the orientation film 23 is formed on the glass substrate 15 on the color filter 17, the black matrix 16, the insulating film 18, and the counter electrode 19 in the same manner as the array substrate 2. did.

A rubbing treatment was applied to the alignment films 22 and 23 of the array substrate 2 and the counter substrate 3 manufactured as described above, and a liquid crystal cell was manufactured with a cell gap of 2 μm. This liquid crystal cell has a spontaneous polarization of 250
nC / cm ² , response speed 70 μs, saturation voltage 1.5
A V / μm thresholdless antiferroelectric liquid crystal material B manufactured by Mitsui Oil Co., Ltd. was injected, and the liquid crystal cell was sealed. Polarizing plates 11 and 14 were provided on both sides of the liquid crystal cell, and an antiferroelectric liquid crystal display device 1 was manufactured.

A VGA having a maximum applied voltage of ± 5 V and a number of pixels of 640 × 480 was used as the array substrate 2 on which the switching elements 6 and 7 were formed. When the antiferroelectric liquid crystal display device 1 manufactured as described above was driven by direct current by inputting a scanning signal only to the gate electrode line 13, the response speed was 60 ms and the contrast ratio was 20, which was suitable for displaying moving images. High-speed response was obtained. Also,
When a scanning signal was simultaneously input to the gate electrode lines 12 and 13 to perform pseudo DC driving, a response speed of 90 ms, a contrast ratio of 80, and a high contrast suitable for display on a monitor or the like could be obtained.

Comparative Example 1 An antiferroelectric liquid crystal display shown in FIG. 6 was formed in the same manner as in Example 1 except that the thickness of the alignment film was formed uniformly and one pixel electrode was used for each pixel. Apparatus 1
01 was produced.

That is, a pixel electrode 109 having an area equal to the sum of the pixel electrode 9 and the pixel electrode 10 is formed on the glass substrate 5, and a switching element (not shown) for switching the pixel electrode 109 is formed. Using the array substrate 102 thus formed, an alignment film 103 made of polyimide was formed on the array substrate 102 with a uniform thickness. Also,
An anti-ferroelectric liquid crystal display device 10 is also formed by forming an alignment film 104 made of polyimide with a uniform thickness on the surface of the counter substrate 3.
1 was produced.

A device was manufactured by changing the thickness of each of the alignment films 103 and 104 in the range of 0 to 100 nm, and the response speed and the contrast ratio of each device were measured in the same manner as in Example 1. FIG. 7 shows the result.

In FIG. 7, the horizontal axis indicates the thickness of the alignment film provided on one substrate, and the vertical axis indicates the response speed and the contrast ratio. Further, a curve 130 shows data on the contrast ratio, and a curve 131 shows data on the response speed. When an insulating film is provided, the same graph is plotted by converting the relative dielectric constant into a polyimide film thickness.

As is clear from this graph, Example 1
The antiferroelectric liquid crystal display device 1 manufactured in Comparative Example 1 has an alignment film thickness of 40 n of the antiferroelectric liquid crystal display device manufactured in Comparative Example 1.
Display performance equivalent to the case of m and 60 nm can be obtained by changing the driving method.

(Example 2) An antiferroelectric liquid crystal display device was manufactured in the same manner as in Example 1 except that the alignment films 22 and 23 were formed as described below.

First, a polyimide film having a thickness of 40 μm was formed on the array substrate 2 in the same manner as in Example 1, and a resist film having a predetermined pattern was formed thereon. Next, 20 μm is formed on the entire surface of the array substrate 2 on which the resist film is formed.
A polyimide film having a thickness of m was formed, and the polyimide film on the resist film was removed together with the resist.

Thus, an alignment film 22 having a thickness of 40 nm on the pixel electrode 9 and a thickness of 60 nm on the pixel electrode 10 was formed. In addition, the alignment film 23 was formed on the counter substrate 3 in the same manner, and the antiferroelectric liquid crystal display device 1 was manufactured.

The response speed and contrast ratio of the antiferroelectric liquid crystal display device 1 manufactured as described above were measured, and the same values as those of the device manufactured in Example 1 were obtained.

(Embodiment 3) An insulating layer made of SiO ₂ is provided on the pixel electrodes 9 and 10 and the counter electrode 19 as described below, and the alignment films 22 and ₂ are formed on these insulating layers.
An antiferroelectric liquid crystal display device on which No. 3 was formed was manufactured.

First, the entire surface of the array substrate 5 on which the pixel electrodes 9 and 10 are formed is the same as that used in the first embodiment.
Using a VD film forming apparatus, a thickness of 34 nm made of SiO ₂
Was formed. This insulating layer has a thickness of 20n.
m has a capacitance equivalent to that of the polyimide alignment film.

Next, a resist pattern is formed on the entire surface of the insulating layer formed on the array substrate 2 as described above.
The exposed insulating layer was removed by etching with hydrofluoric acid. After removing the remaining resist film, a polyimide film having a thickness of 40 nm was formed.

As described above, the thickness 4
A polyimide film having a thickness of 74 nm is formed on the pixel electrode 10 with a thickness of 74 nm.
m of SiO ₂ -polyimide composite film was formed. Note that this composite film has an electric capacity corresponding to a polyimide film having a thickness of 60 nm.

Similarly, a polyimide film and a SiO ₂ -polyimide composite film were formed on the opposing substrate 3 to produce an antiferroelectric liquid crystal display device 1. When the response speed and the contrast ratio of the antiferroelectric liquid crystal display device thus manufactured were measured, values similar to those of the device manufactured in Example 1 were obtained.

(Example 4) An antiferroelectric liquid crystal display device 1 was manufactured in the same manner as in Example 1 except that the alignment films 22 and 23 were formed as described below.

First, 20 nm thick photosensitive polyimide C manufactured by Nippon Synthetic Rubber Co., Ltd. was printed on the entire surface of the pixel electrodes 9 and 10 of the array substrate 2 similar to that used in Example 1.
Next, parallel light having an intensity of 380 mJ / cm ² and a maximum wavelength of 365 nm is irradiated through an exposure mask to form a pixel electrode 1.
Only the photosensitive polyimide film formed on the substrate 0 was selectively exposed. This photosensitive polyimide film has 1. 5kg / cm
^In a nitrogen gas atmosphere of No. ³ , a developer was sprayed at a flow rate of 9 mL / min for 240 seconds, and subsequently, a mixed solution of the developer and the rinsing solution and a rinsing solution were sprayed for 10 seconds each.
Furthermore, spin drying was performed for 20 seconds while blowing nitrogen gas to dry the surface of the array substrate 2.

After a 20-nm-thick polyimide film is formed only on the pixel electrode 10 in this manner, a
A 40 nm thick polyimide film was formed on the pixel electrode 9 and a 60 nm thick polyimide film was formed on the pixel electrode 10 by applying soluble polyimide A to a thickness of 10 nm. The polyimide film formed from the soluble polyimide A and the polyimide film formed from the photosensitive polyimide C had substantially the same relative dielectric constant.

A polyimide film was formed on the opposite substrate 3 in the same manner, and the antiferroelectric liquid crystal display device 1 was manufactured. When the response speed and the contrast ratio of the antiferroelectric liquid crystal display device thus manufactured were measured, values similar to those of the device manufactured in Example 1 were obtained.

Example 5 The antiferroelectric liquid crystal display device shown in FIG. 4 was manufactured as follows. First, a switching element 35 and a pixel electrode 36 made of ITO were formed on the transparent glass substrate 5, and a black matrix 37 was formed on the switching element 35. Next, polyimide A was applied on the surface of the transparent glass substrate 5 on which the pixel electrodes 36 were formed, to form a polyimide film having a thickness of 40 nm. Further, a rubbing treatment was performed on the surface of the polyimide film to form an alignment film 38, thereby forming an array substrate 32 having a BM-on-array structure.

Next, on the glass substrate 15 on which the color filter layer 17 was formed, a 150 nm thick counter electrode 19 was formed.
to form an ITO film of m, to form a SiO ₂ film with a thickness of 8.5nm as the insulating layer 39 on the ITO film. This S
A 150 nm thick IT layer is formed on the iO ₂ film as a conductive layer 41.
An O film is formed in a pattern corresponding to the pixel electrode 36, and a 17 nm thick SiO ₂ film is formed on the ITO film as an insulating layer 40.
A film was formed. Further, a counter substrate 33 was formed by forming an alignment film 42 of polyimide having a thickness of 30 nm on the SiO ₂ film.

The array substrate 32 formed as described above
An antiferroelectric liquid crystal display device 31 was formed in the same manner as in Example 1 except that the counter substrate 33 was used. In addition,
The 8.5-nm-thick SiO ₂ film formed as the insulating layer 39 has an electric capacity corresponding to a 5-nm-thick polyimide film.

A lighting test was performed on the antiferroelectric liquid crystal display device 31 formed as described above. As a result, variations in response speed and contrast in the display surface were observed due to variations in the thickness of the alignment films 38 and 42.

FIG. 5 shows a top view of the antiferroelectric liquid crystal display device 31. In this figure, reference numerals 52 and 53 indicate a signal electrode line and a gate electrode line, respectively, and reference numeral 50
Indicates a pixel having uniform display performance, and reference numeral 51 indicates a pixel having non-uniform display performance. Reference number 4
TFTs and the like are formed at positions indicated by reference numeral 3.

As is apparent from this figure, many pixels 51 having non-uniform display performance were found at the corners of the display surface. Also,
When the variation in the display performance of the pixel 51 with respect to the pixel 50 was converted into the variation in the film thickness of the alignment films 38 and 42 from the graph shown in FIG.
It was found that each alignment film was formed to be about 2.5 nm thick.

Next, a YAG laser beam was applied to the position indicated by reference numeral 43 from the counter substrate 33 side of the ferroelectric liquid crystal display device 31 for the pixel 51 having non-uniform display performance. As a result, the counter electrode 19 shown in FIG.
Then, the insulating layer 39 was melted at the position 43, and the counter electrode 19 and the conductive layer 41 were electrically connected as indicated by reference numeral 44. Accordingly, the variation in the display performance of the pixels 51 is corrected, and an antiferroelectric liquid crystal display device having a uniform display performance in the display surface can be obtained.

In the above, Embodiments 1 to 5 have been described for the case of DC driving. However, the same effect can be obtained for the antiferroelectric liquid crystal display device of Embodiment 5 even in the case of AC driving. Further, in the above-described Examples 1 to 5, the case where the antiferroelectric liquid crystal is used has been described. However, the same effect can be obtained by using the ferroelectric liquid crystal.

[0079]

As described above, according to the present invention,
One pixel is provided with two pixel electrodes that are independently driven, and the electric capacity of a dielectric layer such as an alignment film is different on each pixel electrode. A ferroelectric or antiferroelectric liquid crystal display device capable of controlling
According to the present invention, on the counter electrode, a conductive layer patterned for each pixel is provided via an insulating layer, and a light blocking portion is provided between the switching element and the conductive layer.
Provided is a ferroelectric or antiferroelectric liquid crystal display device capable of controlling display performance by electrically connecting a counter electrode and a conductive layer by irradiating a predetermined position from a display surface with a laser beam. Is done.

[Brief description of the drawings]

FIG. 1 is a sectional view of a liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a top view of an array substrate used in the liquid crystal display device according to the first embodiment of the present invention.

FIG. 3 is an equivalent circuit diagram of an array substrate used in the liquid crystal display device according to the first embodiment of the present invention.

FIG. 4 is a sectional view of a liquid crystal display device according to a second embodiment of the present invention.

FIG. 5 is a top view of a liquid crystal display device according to a second embodiment of the present invention.

FIG. 6 is a cross-sectional view of a conventional anti-liquid crystal display device.

FIG. 7 is a graph showing changes in response speed and contrast ratio with respect to the thickness of an alignment film in a conventional antiferroelectric liquid crystal display device.

[Explanation of symbols]

 1, 31, 101: Liquid crystal display device 2, 32, 102: Array substrate 3, 33: Counter substrate 4, 34: Liquid crystal layer 5: Substrate 6, 7, 35: Switching element 8, 52: Signal electrode line 9, 10 , 109: pixel electrode 11, 14, polarizing plate 12, 13, 53, 105: gate electrode line 15, transparent substrate 16, 37: black matrix 17: color filter layer 18, 39, 40 ... insulating layer 19: counter electrode 20 ... ferroelectric or anti-ferroelectric liquid crystal material 21 ... spacers 22, 23, 38, 42, 103, 104 ... alignment film 41 ... conductive layer 43, 44 ... position 50, 51 ... pixels 130, 131 ... curve

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tsuyoshi Ito 33 Shinisogocho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Inside Toshiba Production Technology Research Institute (72) Inventor Hiroyuki Nagata 33 Shinisogocho, Isogo-ku, Yokohama-shi, Kanagawa Address: Within Toshiba Production Technology Laboratory (72) Inventor Takaki Takato 33, Shinisogocho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Inside Toshiba Production Technology Laboratory (72) Inventor: Haruhiko Okumura Isogo-ku, Yokohama-shi, Kanagawa 33 Shin-Isago-cho Toshiba Production Technology Research Institute

Claims (3)

[Claims] A) a first switching element; a second switching element sharing a signal electrode line with the first switching element; and a source electrode of the first switching element. A first pixel electrode, and a second pixel electrode provided in parallel with the first pixel electrode and electrically connected to a source electrode of the second switching element.
A) a first substrate having a pixel electrode; b) a second substrate having a counter electrode disposed on the surface of the first substrate on which the first and second pixel electrodes are formed, and having a counter electrode on the opposite surface. A substrate, c) provided between the first substrate and the second substrate;
A liquid crystal layer containing a ferroelectric or antiferroelectric liquid crystal material; and d) a region provided between the first and second pixel electrodes and the counter electrode, between the first pixel electrode and the counter electrode. And a region between the second pixel electrode and the counter electrode, and a dielectric layer having a different electric capacitance. 2. A first substrate comprising: a) a switching element; and a pixel electrode electrically connected to a source electrode of the switching element; b) a counter electrode; and an insulating layer provided on the counter electrode. A second substrate, comprising: a conductive layer provided at a predetermined position on the insulating layer; and a second substrate disposed to face a surface of the first substrate on which a pixel electrode is formed; Provided between the first substrate and the second substrate,
A liquid crystal layer containing a ferroelectric or antiferroelectric liquid crystal material; d) an alignment film provided on at least one of the first substrate and the second substrate in contact with the liquid crystal layer; and e) the switching element. And a light blocking portion provided between the conductive layer and the conductive layer, wherein the conductive layer is provided corresponding to the pixel electrode and the switching element of the first substrate, and the switching element of the counter electrode and the conductive layer is provided. A liquid crystal display device, wherein the opposite electrode and the conductive layer are electrically connected by irradiating a laser beam to a portion corresponding to. 3. The liquid crystal display device according to claim 2, wherein the light blocking portion is a black matrix.