JPH0822033A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To obviate the inversion of a halftone contrast display even when a visual angle is inclined forward as the voltages impressed to respective display electrodes constituting one pixel vary, to obtain a high contrast as a nonlinear resistance element structure is Ta-Ta2O5-ITO and to obtain a specified display characteristic even if a photoetching stage fluctuates as the areas of the nonlinear resistance elements are constant. CONSTITUTION:This liquid crystal display device has a first substrate having the nonlinear resistance elements consisting of first electrodes 2, nonlinear resistance layers and second electrodes 4 formed of indium tin oxide films, display electrodes and driving electrodes 9 and a second substrate having counter electrodes 11. The one pixel is composed of the one counter electrode 11, the plural display electrodes 6, 8 and the nonlinear resistance elements 5, 7 connected to these display electrodes 6, 8 and is so constituted that the areas of the display electrodes are the same and that the areas of the nonlinear resistance elements 5, 7 vary.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a metal-insulator-metal or metal-insulator-transparent conductor structure (hereinafter referred to as MIM) used in a liquid crystal switching element applied to an active matrix liquid crystal display panel. The present invention relates to the structure of a liquid crystal display panel having a nonlinear resistance element.

[0002]

2. Description of the Related Art In recent years, the display capacity of a liquid crystal display device using a liquid crystal display panel has been increasing. In the display system using the multiplex drive for the display device having the simple matrix configuration, the contrast or the response speed is lowered as the time division is increased. Therefore, in a display device having about 200 scanning lines,
It becomes difficult to obtain sufficient contrast.

Therefore, in order to eliminate such a defect, an active matrix type liquid crystal display panel in which a switching element is provided in each pixel has been adopted.

This active matrix type liquid crystal display panel has a three-terminal system using thin film transistors (TFTs) as a switching element and a two-terminal system using a non-linear resistance element. Among them, the two-terminal system is superior in that the structure and the manufacturing method are simple.

For the two-terminal system, diode type, varistor type, MIM type, etc. have been developed. this house,
The MIM type is characterized by a particularly simple structure and a short manufacturing process.

FIG. 6 shows a conventional M using a non-linear resistance element.
It is a top view which shows the structure of an IM type liquid crystal display device. Further, FIG. 7 is a cross-sectional view showing a cross section taken along the line AA in the plan view of FIG. The prior art will be described below by alternately using FIG. 6 and FIG. 7.

A first electrode 32 is provided on the first substrate 31, and a non-linear resistance layer 33 is provided on the first electrode 32. Further, the second electrode 34 is provided so as to overlap the non-linear resistance layer 33 to form the non-linear resistance element 30. A part of the second electrode 34 also serves as the display electrode 35.

The display electrode 35 is formed on the second substrate 36.
A counter electrode 39 is provided so as to face the.

A first electrode 32 provided on a first substrate 31
Is normally the first electrode 32, as shown in the plan view of FIG.
It is connected to the drive electrode 38 formed of the same material as the above, and is arranged with a constant space dimension from the display electrode 35.

The display electrode 35 constitutes one pixel of the liquid crystal display panel by arranging the display electrode 35 so as to overlap the counter electrode 39.

Further, the first substrate 31 and the second substrate 36 are provided with alignment films 40 and 40, respectively, as processing layers for regularly arranging the molecules of the liquid crystal 41.

Furthermore, by means of the spacer 42,
The first substrate 31 and the second substrate 36 are opposed to each other with a predetermined gap, and the liquid crystal 41 is sealed between the first substrate 31 and the second substrate 36.

When the scanning signal is applied to the drive electrode 38, the display electrode 35 can be controlled to a desired brightness by applying the data signal to the counter electrode 39.

Conversely, even if a scanning signal is applied to the counter electrode 39 and a data signal is applied to the drive electrode 38, the display electrode 35 can be controlled to have a desired brightness.

Of the write voltage Vin applied between the drive electrode 38 and the counter electrode 39 during writing, the voltage Vmim applied to the nonlinear resistance element 30 is the capacitance C of the display electrode 35.
Using the capacitance ratio CR which is a value obtained by dividing lc by the capacitance Cmim of the nonlinear resistance element 30, Vmim = Vin × CR / (1
+ CR).

Since the resistance of the non-linear resistance element 30 becomes lower as the applied voltage becomes higher, if the capacitance ratio CR is large, Vmim.
Becomes large, the resistance of the nonlinear resistance element 30 becomes low, and a data signal can be effectively written in the liquid crystal.

At the time of holding after writing is completed, the display electrode 35
The voltage Vlc held in the liquid crystal 41 between the counter electrode 39 and the counter electrode 39 is
The voltage drops by ΔV due to capacitive coupling between Clc and Cmim, and is represented by ΔV = Vin / (1 + CR).

Therefore, the larger the capacity ratio CR, the more ΔV
Becomes smaller. As a result, the voltage Vl held in the liquid crystal 41
c can be increased. After that, until the next writing, liquid crystal 4
The voltage Vlc held at 1 is held by the liquid crystal capacitance Clc.

[0019]

By the way, in the conventional liquid crystal display panel, the twisted nematic (in which the alignment state of the liquid crystal 41 is twisted by 80 to 100 degrees between the first substrate 31 and the second substrate 36). TN) mode. This T
The N-mode liquid crystal display panel changes in brightness when the liquid crystal display panel is tilted to the front, rear, left and right, and has a bad viewing angle characteristic.

FIG. 8 shows the display characteristics of the conventional liquid crystal display panel in the front-rear direction. The horizontal axis represents the display electrode 35 and the counter electrode 39.
The applied voltage between the two is shown, and the vertical axis shows the transmittance. In a normally white mode, the upper and lower polarizing plates are installed in a 90 ° twisted TN mode liquid crystal display panel so as to be orthogonal to each other by 90 °.

The solid line L in the graph of FIG. 8 shows the transmittance-voltage characteristics when the liquid crystal display panel is viewed from the front, and the solid line M.
Indicates the transmittance-voltage characteristic when tilted forward by 40 °, and the solid line N indicates the transmittance-voltage characteristic when tilted backward by 40 °.

On the front side, the voltage of V1 may be applied for producing a black display, the voltage of V3 may be applied for producing a white display, and the voltage of V2 may be applied for producing a gray display of halftone. Apply.

When the liquid crystal display panel is tilted backward by 40 ° while displaying the gray display and the black display, the black display changes from the intersection of the solid line L and the straight line V1 to the intersection of the solid line N and the straight line V1 and becomes bright. . On the other hand, the gray display changes from the intersection of the solid line L and the straight line V2 to the intersection of the solid line N and the straight line V2, and the display becomes considerably white and the contrast decreases.

On the contrary, when the liquid crystal display panel is tilted by 40 ° in the forward direction, the black display changes from the intersection of the solid line L and the straight line V1 to the intersection of the solid line M and the straight line V1 and becomes bright, but the gray display shows the solid line. From the intersection of L and the straight line V2, the solid line M and the straight line V
It changes to the intersection of 2 and becomes black on the contrary, and inversion of black and gray display occurs. Therefore, there is a problem that the display quality is significantly reduced.

As a means for improving the viewing angle characteristic, there is a means disclosed in Japanese Patent Laid-Open No. 53150/1993.
This publication describes that one pixel is composed of a plurality of display electrodes and a non-linear resistance element connected to the display electrodes, and that the display electrodes and the non-linear resistance elements have different capacitance ratios.

The configuration of the liquid crystal display device described in this publication will be described with reference to FIG. 9, which is a drawing rotated 90 ° from the drawing shown in FIG. 1 in JP-A-5-53150.

One pixel is composed of one counter electrode 51, a first display electrode 54 and a second display electrode 55. Moreover, the area ratio between the first display electrode 54 and the first nonlinear resistance element 58 and the area ratio between the second display electrode 55 and the second nonlinear resistance element 59 are changed.

Therefore, the capacitance ratio between the first display electrode 54 and the first non-linear resistance element 58, and the second display electrode 55.
And the capacitance ratio of the second non-linear resistance element 59 is different, and even if the same data signal is written, the drive voltage of the first display electrode 54 and the second display electrode 55 changes.

The operation of improving the viewing angle characteristics in the liquid crystal display device will be described with reference to the graph of FIG. The horizontal axis of FIG. 5 represents the voltage applied between the drive electrode 50 and the counter electrode 51, and the vertical axis represents the transmittance of the liquid crystal display device.

The solid line X indicates the capacitance ratio CR = display electrode capacitance Cl.
c / non-linear resistance element shows a voltage-transmittance curve tilted by 40 ° in the forward direction when the second display electrode 55 has a large capacitance Cmim, and the solid line Y indicates the first display electrode 54 having a small capacitance ratio.
In this case, the voltage-transmittance characteristic inclined by 40 ° in the forward direction is shown.

In the first display electrode 54 having a small capacitance ratio,
The voltage applied to the non-linear resistance element at the time of writing decreases, the resistance of the non-linear resistance element does not become sufficiently small, and the writing efficiency decreases. Furthermore, since the voltage drop amount ΔV during holding also becomes large, a high voltage must be applied as compared with a display electrode having a high capacitance ratio, and therefore the solid line Y moves to a higher voltage side than the solid line X.

The brightness of a pixel is the average of a plurality of display electrodes. The average voltage-transmittance curve is shown by the dashed line Z. When the applied voltage V1 for black display and V2 for gray display are applied when viewed from the front, black gray inversion occurs in the solid line X, but the broken line Z
In, black ash inversion does not occur, and the viewing angle characteristic in the forward direction is improved.

However, the steepness of the broken line Z in FIG.
As can be seen from the fact that the steepness of the solid line X is lower, the steepness of the front voltage-transmittance curve L is also lower.
Therefore, in order to display black, the voltage V in FIG.
A voltage of 1 or more is required, and a driving capability of the non-linear resistance element is required to be higher than V1-V3.

The driving ability of the MIM element is determined by the element structure, the element configuration, the element material, and the manufacturing conditions. The element material has the greatest influence.

The non-linear resistance element used in the above-mentioned Japanese Patent Laid-Open No. 05-053150 has a first electrode 52 and a non-linear resistance layer provided by anodizing the first electrode 52 as shown in FIG. , The second electrode 56 and the second electrode 57.

Although not described in detail in this publication, it is clear that the materials of the second electrodes 56 and 57 and the display electrodes 54 and 55 are different. And the second electrode 5
It is presumed that a metal film of chromium (Cr) or the like is used as each of 6, 57.

A non-linear resistance element formed of a Ta-Ta ₂ O ₅ -Cr element material using a tantalum (Ta) film as the first electrode 52 has a small driving ability. For this reason, a sufficiently large driving voltage cannot be applied, and the display contrast is lowered, so that it is difficult to put it into practical use even if the viewing angle characteristic is improved.

Furthermore, in any of FIGS. 1, 5 and 6 of Japanese Patent Laid-Open No. 53150/1993, a large area non-linear resistance element is used for a large area display electrode, and an area large area is used for a small area display electrode. Is connected to a small non-linear resistance element.

Therefore, the amount of change in the area ratio between the display electrodes and the non-linear resistance element is small, the difference in the capacitance ratio is small, and it is difficult to increase the drive voltage difference between the display electrodes. I can't get it.

Furthermore, since the very small second non-linear resistance element 59 is used, the probability that the area ratio is changed by over-etching or under-etching in the photo-etching process for forming the non-linear resistance element is the first.
Second non-linear resistance element 59 rather than the non-linear resistance element 58 of
Is bigger. For this reason, the drive voltage varies from substrate to substrate.

An object of the present invention is to provide a MIM having a large driving ability.
By using multiple display electrodes that have a large difference in capacitance ratio between the display element and the non-linear resistance element, it is possible to suppress the inversion of black and gray display that occurs when the liquid crystal display panel is tilted forward and to achieve a good viewing angle. An object of the present invention is to provide a structure of a liquid crystal display device having characteristics and having sufficient contrast.

Further, an object of the present invention is to provide a liquid crystal display device in which even if over-etching or under-etching in the photo-etching process is performed, the driving voltage difference between a plurality of display electrodes does not change so much and constant display characteristics are always obtained. Is to provide the structure of.

[0043]

In order to achieve the above object, a liquid crystal display device of the present invention comprises a non-linear resistance element comprising a first electrode, a non-linear resistance layer and a second electrode, a display electrode and a drive electrode. A first substrate having a counter electrode, a second substrate having a counter electrode, and a liquid crystal sealed between the first substrate and the second substrate, and one pixel having one counter electrode and a plurality of displays. It consists of an electrode and a non-linear resistance element connected to each display electrode,
Each of the non-linear resistance elements has the same area and the display electrodes have different areas, and the non-linear resistance element and the display electrode have different capacitance ratios.

Further, the liquid crystal display device of the present invention has a first substrate having a non-linear resistance element including a first electrode, a non-linear resistance layer and a second electrode, a display electrode and a drive electrode, and a counter electrode. A second substrate and a liquid crystal sealed between the first substrate and the second substrate are provided, and one pixel includes one counter electrode, a plurality of display electrodes, and a non-linear resistance element that connects each display electrode. And the area of each display electrode is the same, and the area of the non-linear resistance element is different,
The non-linear resistance element and the display electrode have different capacitance ratios.

Further, the liquid crystal display device of the present invention has a first substrate having a non-linear resistance element including a first electrode, a non-linear resistance layer and a second electrode, a display electrode and a drive electrode, and a first substrate having a counter electrode. A second substrate and liquid crystal sealed between the first substrate and the second substrate, and one pixel is connected to one counter electrode, a plurality of display electrodes of different sizes, and a plurality of display electrodes. The non-linear resistance element is composed of non-linear resistance elements of different sizes, and a large-area display electrode is connected to a small-area non-linear resistance element, and a small-area display electrode is connected to a large-area non-linear resistance element. And a display electrode having a different capacitance ratio.

Furthermore, the liquid crystal display device of the present invention comprises the first
The second electrode formed on the substrate is formed of a transparent conductive film that is the same material as the display electrode.

Furthermore, the liquid crystal display device of the present invention comprises the first
An insulating thin film is provided on the non-linear resistance element of the substrate, or on the non-linear resistance element and the display electrode of the first substrate.

[0048]

The pixel structure of the liquid crystal display device of the present invention is a structure in which one pixel is divided into a plurality of pixels having different capacitance ratios of the nonlinear resistance element capacitance and the display electrode capacitance, and the capacitance ratios are different. Therefore, even if the same data signal is written, the applied voltage to each display electrode changes, and the voltage-
The transmittance characteristic becomes gentle, and the viewing angle characteristic can be improved.

Further, a plurality of display electrodes forming one pixel and a non-linear resistance element connected to the display electrode are made to have a constant area of the non-linear resistance element and different only in the area of the display electrode. As a result, the rate of change of the capacitance ratio can be made larger than that of the conventional example, and the effect of improving the viewing angle characteristics can be made larger.

Further, even if over-etching or under-etching occurs in the photo-etching process, the area of the non-linear resistance element remains the same. Therefore, the variation ratio of the capacity ratio is small, and a constant display characteristic can be obtained.

Furthermore, an indium tin oxide film, which is a transparent conductive film, which is the same material as the display electrode, is used as the second electrode material to form an element structure of Ta-Ta ₂ O ₅ -ITO. As a result, the driving capability of the MIM element is improved, and the viewing angle characteristics can be improved without lowering the contrast.

[0052]

The structure of a liquid crystal display device according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a plan view showing the structure of the liquid crystal display device according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view showing a cross section taken along the line BB in the plan view of FIG. Hereinafter, the configuration of the liquid crystal display device according to the first embodiment of the present invention will be described by alternately using FIG. 1 and FIG.

A first electrode 2 made of a tantalum (Ta) film is provided on the first substrate 1. Further, a non-linear resistance layer 3 made of a tantalum oxide (Ta ₂ O ₅ ) film provided by anodizing the first electrode 2 is provided on the first electrode 2.

Further, a second electrode 4 made of an indium tin oxide (ITO) film is provided as a transparent conductive film on the nonlinear resistance layer 3.

The first electrode 2, the non-linear resistance layer 3 and the second
The first non-linear resistance element 5 and the second non-linear element 7 of the MIM structure are constituted by the electrode 4 of the above.

As shown in the plan view of FIG. 1, a partial region of the second electrode 4 serves as both the first display electrode 6 and the second display electrode 8. The first electrode 2 is connected to the drive electrode 9 made of a tantalum film.

The areas of the first display electrode 6 and the second display electrode 8 are different from each other. In the embodiment of the present invention, the area of the first display electrode 6 is equal to the area of the second display electrode 8.
It is configured to be about 30% larger.

Further, a counter electrode 11 made of an indium tin oxide film is provided on the second substrate 10 so as to face the first display electrode 6 and the second display electrode 8.

By arranging the first display electrode 6 and the second display electrode 8 so as to overlap with the counter electrode 11, respectively, the first display electrode 6 and the second display electrode 8 are provided. It becomes one pixel of the liquid crystal display device and performs a predetermined display.

Further, the first substrate 1 and the second substrate 10 are provided with alignment films 12 and 12, respectively, as processing layers for regularly aligning the molecules of the liquid crystal 13. Furthermore, the spacer 14 causes the first substrate 1 and the second substrate 10 to face each other with a predetermined distance, and
A liquid crystal 13 is sealed between the substrate 1 and the second substrate 10.

Next, the operation of the liquid crystal display device according to the first embodiment of the present invention described above will be described.

In the first embodiment of the present invention, a 4-inch black and white liquid crystal display device is used. 640 horizontal by 10 cm diagonally across the display
Pixel x 240 pixels vertically, pixel pitch is 125 μm horizontally x 2 pixels vertically
It is 40 μm.

The first display electrode 6 is 65 μm wide × 200 vertical.
The second display electrode 8 has a width of 45 μm and a length of 200 μm.
m, the first nonlinear resistance element 5 and the second nonlinear resistance element 7
Has an area of 3 μm × 3 μm, and the liquid crystal gap is 4 μm.

The nonlinear resistance layer 3 is as thin as about 0.07 μm, and has a dielectric constant of 25 to 30, which is 5 to 10 times larger than the dielectric constant of 3 to 5 of the liquid crystal. Therefore, the capacitance ratio between the first display electrode 6 and the first non-linear resistance element 5 is about 4, and the capacitance ratio between the second display electrode 8 and the second non-linear resistance element 7 is about 3.

Therefore, the voltage Vmim1 applied to the first nonlinear resistance element 5 at the time of writing becomes 4/5 Vin, and the voltage Vmim applied to the second nonlinear resistance element 7.
2 becomes 3/4 Vin, and Vmim2 = Vmim1 × 1
It becomes 5/16.

Applied voltage V between the drive electrode 9 and the counter electrode 11
When about 10 V is applied as in, a voltage difference of about 0.5 V is generated between the first display electrode 6 and the second display electrode 8.

In FIG. 5, the solid line X represents the voltage-transmittance characteristic of the first display electrode 6 having a capacitance ratio of 4 tilted forward by 40 °, and the solid line Y represents the second display electrode 8 having a capacitance ratio of 3. It shows the voltage-transmittance characteristic inclined by 40 ° in the forward direction.

The pixel brightness is the average of the two display electrodes, and the average voltage-transmittance curve is shown by the broken line Z. When the applied voltage V1 for black display and V2 for gray display are applied when viewed from the front, black grey inversion occurs in the solid line X, but black grey inversion does not occur in the broken line Z showing the characteristics of the present invention. , The viewing angle characteristics in the forward direction have been improved.

Since the material of Ta-Ta ₂ O ₅ -ITO is used for the first non-linear resistance element 5 and the second non-linear resistance element 7, the driving capability of the MIM element is high and sufficient contrast characteristics are obtained. Obtainable.

In the first embodiment of the present invention, the first
The areas of the non-linear resistance element 5 and the second non-linear resistance element 7 are made constant, and only the areas of the display electrodes of the first display electrode 6 and the second display electrode 8 are different from each other. This makes it possible to increase the rate of change of the capacity ratio compared to the conventional example,
The effect of improving the viewing angle characteristics can be increased.

Further, even if the non-linear resistance element area changes due to over-etching or under-etching in the photo-etching process, the areas of the first non-linear resistance element 5 and the second non-linear resistance element 7 are the same. For this reason, the change in voltage difference between the first display electrode 6 and the second display electrode 8 is small, and constant display characteristics can always be obtained.

Next, a method of manufacturing the liquid crystal display device according to the first embodiment of the present invention will be briefly described with reference to FIGS.

The first substrate 1 is preferably made of glass having a low content of alkali metals. In the first embodiment of the present invention, a product name OA2 manufactured by Nippon Electric Glass Co., Ltd. having a thickness of 1.1 mm is used. To use.

Next, as the material of the first electrode 2 and the drive electrode 9 on the first substrate 1, the entire surface has a thickness of 0.1 to 0.3 μm.
The tantalum film is formed by a sputtering method or a vacuum evaporation method. After that, the tantalum thin film is patterned by dry etching using SF ₆ and a mixed gas of helium and oxygen as an etching gas to form the first electrode 2 and the driving electrode 9. The wiring line width of the drive electrode 9 is 20 μm,
The line width of the nonlinear element portion of the first electrode 2 is 3 μm.

Next, the first substrate 1 is immersed in an anodizing bath filled with an anodizing solution such as citric acid or ammonium borate, and a direct current voltage of 30V to 50V is applied to the anodizing treatment to achieve a thickness of 0. A nonlinear resistance layer 3 made of a tantalum oxide (Ta ₂ O ₅ ) film having a thickness of 0.05 to 0.1 μm is formed.

Further, as a material for the second electrode 4 and a material for the display electrode, an indium tin oxide film, which is a transparent conductive film, is formed on the entire surface by a sputtering method or a vacuum evaporation method to a thickness of 0.1.
The second electrode 4, the first display electrode 6, and the second display electrode 8 are provided by a photo etching process. In the first embodiment of the present invention, the indium tin oxide film is etched using a mixed solution of ferric chloride and hydrochloric acid, and the line width of the second electrode 4 is set to 3 μm.

Next, a method of manufacturing the second substrate 10 will be described. The second substrate 10 is also the same glass substrate as the first substrate 1, and an indium tin oxide film having a thickness of 0.1 to 0.4 μm is provided as a material of the counter electrode 11 by a sputtering method or a vacuum evaporation method. The counter electrode 11 is provided by photo etching.

After the alignment film 12 is formed on both the first substrate 1 and the second substrate 10 by a printing method, a rubbing process is performed, and the spacer 14 is sandwiched between the two substrates by an epoxy adhesive. The liquid crystal 13 is injected by laminating at a predetermined interval.

Then, a polarizing plate is attached to the outside of the first substrate 1 and the second substrate 10 so that the polarization axes intersect each other at 90 °, and the normally white mode MIM active matrix liquid crystal display device is obtained.

In the first embodiment of the present invention, the liquid crystal 13 is
A fluorine-based material with Δn = 0.13 is used, and the cell gap is 4 μm.

The 4-type MIM type black and white liquid crystal display device according to the embodiment of the present invention has a sufficient contrast characteristic even on the front side, and further the viewing angle characteristic when tilted in the front-back direction is improved. Good display quality is obtained. Furthermore, the viewing angle characteristic when tilted in the left-right direction is numerically the same as that of the conventional one, but when viewed, the vertical viewing angle component is included, so that it appears wider than before.

In the first embodiment of the present invention, it is preferable that the first non-linear resistance element 5 and the second non-linear resistance element 7 of the first substrate 1 are provided, or the first non-linear resistance element 7 of the first substrate 1 is provided. On the non-linear resistance element 5, the second non-linear resistance element 7, the first display electrode 6 and the second display electrode 8, a silicon dioxide or an oxide having a thickness of 0.1 to 0.5 μm is formed by a sputtering method. An insulating film of tantalum is provided. This insulating film is used for the first non-linear resistance element 5 and the second non-linear resistance element 7 and the liquid crystal 13.
Remove the interaction of. As a result, the image sticking phenomenon is reduced, and a display image of higher quality can be provided.

In the first embodiment of the present invention, one pixel is composed of two sets of non-linear resistance elements and display electrodes, but it is also possible to compose three or more sets of non-linear resistance elements and display electrodes.

Next, a second embodiment of the liquid crystal display device of the present invention will be described with reference to FIGS. 3 and 4. FIG.
It is sectional drawing which shows the structure of the 2nd Example of this invention, and shows the cross section in the CC line of the top view of FIG. Below, FIG.
The configuration of the liquid crystal display device according to the second embodiment of the present invention will be described by alternately using FIG.

A first electrode 2 made of a tantalum (Ta) film is provided on the first substrate 1, and the first electrode 2 is further provided.
A non-linear resistance layer 3 made of a tantalum oxide (Ta ₂ O ₅ ) film provided by anodizing the first electrode 2 is provided thereon.

Further, a second electrode 4 made of an indium tin oxide (ITO) film is provided as a transparent conductive film on the nonlinear resistance layer 3.

The first electrode 2, the non-linear resistance layer 3 and the second
The first non-linear resistance element 5 and the second non-linear element 7 having the MIM structure are provided by the electrode 4 of FIG.

As shown in the plan view of FIG. 3, a partial region of the second electrode 4 serves as both the first display electrode 6 and the second display electrode 8. The first electrode 2 is connected to the drive electrode 9 made of a tantalum film.

In the second embodiment of the present invention, the area of the first display electrode 6 and the area of the second display electrode 8 are the same. However, the line width of the first electrode 2 forming the first nonlinear resistance element 5 is 3 μm, and the line width of the first electrode 2 forming the second nonlinear resistance element 7 is 4 μm. Configure with different line width dimensions.

Further, the second substrate 10 is provided with a black matrix 15 formed by patterning a chrome film into a shape shown by a diagonal line descending to the right in FIG. Further, color filters 16 and 17 are provided on the display section.

An insulating film 18 made of acrylic resin is provided on the color filters 16 and 17. Further, a counter electrode 11 made of an indium tin oxide film is provided so as to face the first display electrode 6 and the second display electrode 8.

The first display electrode 6 and the second display electrode 8 are arranged so as to overlap the counter electrode 11. As a result, one pixel of the liquid crystal display panel is formed by both the first display electrode 6 and the second display electrode 8, and a predetermined display is performed.

Further, the first substrate 1 and the second substrate 10 are provided with alignment films 12 and 12, respectively, as processing layers for regularly aligning the molecules of the liquid crystal 13. Furthermore, the spacer 14 allows the first substrate 1 and the second substrate 1 to be
0 and 0 are opposed to each other at a predetermined interval. Liquid crystal 13 is sealed between the first substrate 1 and the second substrate 10.

The operation of the liquid crystal display device according to the second embodiment of the present invention will be described next.

In the second embodiment of the present invention, a 4-type color liquid crystal display device is used. The width of the display is 10 cm and the width is 64 cm.
0 pixels x 240 pixels vertically, pixel pitch size is 125μ horizontally
m × length 240 μm.

The first display electrode 6 and the second display electrode 8 are
The width is the same as 55 μm × 200 μm in length, but the line width of the first electrode 2 of the first non-linear resistance element 5 is 3 μm, the line width of the second electrode 4 is 3 μm, and the area is 9 μm ² . The line width of the first electrode 2 of the nonlinear resistance element 7 is 4 μm, the line width of the second electrode 4 is 3 μm, and the area is 12 μm ² . The liquid crystal gap is 4 μm.

The nonlinear resistance layer 3 is as thin as about 0.07 μm and has a dielectric constant of 25 to 30 which is 5 to 10 times larger than the dielectric constant of 3 to 5 of the liquid crystal.

Therefore, the capacitance ratio between the first display electrode 6 and the first non-linear resistance element 5 is about 4, and the capacitance ratio between the second display electrode 8 and the second non-linear resistance element 7 is about 3. .

Therefore, the voltage Vmim1 applied to the first nonlinear resistance element 5 at the time of writing becomes 4/5 Vin,
The voltage Vmim2 applied to the second nonlinear resistance element 7 is 3
Becomes / 4 Vin, and Vmim2 = Vmim1 × 15/1
It becomes 6.

Applied voltage V between the drive electrode 9 and the counter electrode 11
When about 10 V is applied as in, a voltage difference of about 0.5 V is generated between the first display electrode 6 and the second display electrode 8.

In FIG. 5, the solid line X represents the voltage-transmittance characteristic of the first display electrode 6 having a capacitance ratio of 4 tilted forward by 40 °, and the solid line Y represents the second display electrode 8 having a capacitance ratio of 3. It shows the voltage-transmittance characteristic inclined by 40 ° in the forward direction.

The brightness of a pixel is the average of a plurality of display electrodes, and the average voltage-transmittance curve is shown by a broken line Z. When applying the applied voltage V1 for black display and V2 for gray display as viewed from the front, black grey inversion occurs in the solid line X, but in the broken line Z showing the characteristics of the present invention, black grey inversion does not occur, The viewing angle characteristics in the forward direction are improved.

Since the material of Ta-Ta ₂ O ₅ -ITO is used for the first nonlinear resistance element 5 and the second nonlinear resistance element 7, the driving ability of the MIM element is high and sufficient contrast characteristics are obtained. Obtainable.

Further, the areas of the first display electrode 6 and the second display electrode 8 are made constant, and only the areas of the first nonlinear resistance element 7 and the second nonlinear resistance element 7 are different. There is. As a result, the rate of change of the capacitance ratio can be made larger than that of the conventional example, and the effect of improving the viewing angle characteristics can be made larger.

Further, even if the display electrode area changes due to over-etching or under-etching in the display electrode forming step, the first display electrode 6 and the second display electrode 8 are formed.
Have the same area. For this reason, the change in voltage difference between the first display electrode 6 and the second display electrode 8 is small, and constant display characteristics can always be obtained.

Even if the non-linear resistance area changes due to over-etching or under-etching in the process of forming the non-linear resistance element, the first non-linear resistance element 5 is provided more than the conventional example.
And the area difference between the second non-linear resistance element 7 is small. Therefore, the change in the voltage difference between the first display electrode 6 and the second display electrode 8 is reduced, and a constant display characteristic can be obtained.

Next, a method of manufacturing the liquid crystal display device according to the second embodiment of the present invention will be briefly described with reference to FIGS.

The first substrate 1 is preferably made of glass having a low content of alkali metal. In the second embodiment of the present invention, a product name OA2 manufactured by Nippon Electric Glass Co., Ltd. having a thickness of 1.1 mm is used. To use.

Next, on the first substrate 1, as a material of the first electrode 2 and the driving electrode 9, a thickness of 0.1 to 0.3 μm is formed on the entire surface.
A tantalum film of m is provided by a sputtering method or a vacuum evaporation method. After that, by dry etching using a mixed gas of SF ₆ , helium and oxygen as an etching gas,
The tantalum film is patterned to provide the first electrode 2 and the drive electrode 9. Here, the wiring line width of the drive electrode 9 is 20
μm, the line width of the first electrode 2 of the first nonlinear resistance element 5 is 3 μm, and the line width of the first electrode 2 of the second nonlinear resistance element 7 is 4 μm.

Next, the first substrate 1 is immersed in an anodizing tank filled with an anodizing solution such as citric acid or ammonium borate, and a direct current voltage of 30V to 50V is applied to the anodizing treatment to achieve a thickness of 0. A non-linear resistance layer 3 made of a tantalum oxide (Ta ₂ O ₅ ) film having a thickness of 0.05 to 0.1 μm is provided.

Further, as a material for the second electrode 4 and a material for the display electrode, an indium tin oxide film which is a transparent conductive film is formed on the entire surface to a thickness of 0.1 by a sputtering method or a vacuum evaporation method.
To 0.3 μm. Then, the second electrode 4, the first display electrode 6, and the second display electrode 8 are provided by photoetching. In the example of the present invention, etching is performed using a mixed solution of ferric chloride and hydrochloric acid. The line width of the second electrode 4 is 3 μm.

Next, a method of manufacturing the second substrate 6 will be described. The second substrate 10 is also the same glass substrate as the first substrate 1, and a chromium film having a thickness of 0.1 to 0.2 μm is formed on the entire surface by sputtering or vacuum evaporation.
Then, the chromium film is photoetched using a mixed solution of cerium ammonium nitrate and perchloric acid to form the black matrix 15.

Then, a photosensitive organic material such as gelatin or casein is formed on the entire surface by spin coating. Then, after the drying treatment, photoetching is performed to impregnate the second substrate 10 into the dyeing tank for dyeing, and to impregnate the fixing tank by impregnating the second substrate 10 to fix the green color filter-1 having a thickness of 1 μm.
6 is provided. This process is repeated 3 times to provide a blue color filter 17 and a red color filter (not shown).

After the acrylic organic material is formed on the color filters 16 and 17 as the material of the insulating film 18 by the spin coating method, the organic material is heat-treated at a temperature of 150 to 200 ° C. Is cured to form an insulating film 18 having a thickness of 2 to 5 μm.

Next, as a material for the counter electrode 11, an indium tin oxide film having a thickness of 0.2 to 0.4 μm is provided by the low temperature sputtering method, and the counter electrode 11 is provided by photoetching.

After the alignment film 12 is formed on both the first substrate 1 and the second substrate 10 by a printing method, a rubbing process is performed.
Both substrates are bonded at a predetermined interval with an epoxy adhesive sandwiching the spacer 14, and the liquid crystal 13 is injected.

Polarizing plates were attached to the outside of both substrates so that the polarization axes crossed 90 °, and the MI of normally white mode was set.
It becomes an M type active matrix liquid crystal display device.

In the embodiment of the present invention, the liquid crystal 13 is made of a fluorine-based material with Δn = 0.13 and has a cell gap of 4 μm.
to m.

The 4-type MIM type color liquid crystal display device of the second embodiment of the present invention has a sufficient contrast characteristic even on the front side, and can further improve the viewing angle characteristic when tilted in the front-back direction. It is possible to obtain good display quality without inversion of halftone. Further, the viewing angle characteristic when tilted in the left-right direction is the same as that of the conventional one in terms of numerical values, but when viewed, the component of the vertical viewing angle is included, so that it looks wider than before.

In the second embodiment of the present invention, it is preferable that the first non-linear resistance element 5 and the second non-linear resistance element 7 of the first substrate 1 are provided, or the first non-linear resistance element of the first substrate 1 is made. Resistance element 5, second nonlinear resistance element 7, and first display electrode 6
An insulating film of silicon dioxide or tantalum oxide having a thickness of 0.1 to 0.5 μm is provided on the second display electrode 8 by the sputtering method. This insulating film has a role of removing the interaction between the first nonlinear resistance element 5, the second nonlinear resistance element 7 and the liquid crystal 13. As a result, the image sticking phenomenon is reduced, and a display image of higher quality can be provided.

In the second embodiment of the present invention, one pixel is composed of two sets of nonlinear resistance elements and display electrodes, but it is also possible to form three pixels or more of non-linear resistance elements and display electrodes.

In the second embodiment of the present invention, the first non-linear resistance element 5 and the second non-linear resistance element 7 are used to form the second electrode 4.
And the line width of the first electrode 2 is 3 μm.
Although the line width of the first electrode 2 is changed to 3 μm, the line width of the second electrode 4 is changed to 3 μm.
Even if the thickness is changed to μm and 4 μm, the same effect can be obtained.

Further, in the first nonlinear resistance element 5 and the second nonlinear resistance element 7, the line width of the first electrode 2 and the second electrode 4 are
It is also possible to change both the line width and the line width. By changing the line widths of both the first electrode 2 and the second electrode 4, the areas of the first nonlinear resistance element 5 and the second nonlinear resistance element 7 can be greatly changed.

Further, the areas of the first display electrode 6 and the second display electrode 8 are changed, and the first nonlinear resistance element 5 and the second display electrode 8 are changed.
It is also possible to change the area with the non-linear resistance element 7. At this time, the area of the first display electrode 6 is made larger than that of the second display electrode 8, and the area of the first nonlinear resistance element 5 is made smaller than that of the second nonlinear resistance element 7.

In the liquid crystal display device of the present invention, the capacitance ratio can be changed more than in the conventional example, and the voltage difference between the first display electrode 6 and the second display electrode 8 can be increased. Like

Further, if the capacitance ratio difference is the same as that of the conventional example, the area difference between the first display electrode 6 and the second display electrode 8,
Further, the area difference between the first nonlinear resistance element 5 and the second nonlinear resistance element 7 can be reduced. Therefore, even if over-etching or under-etching in the photo-etching process occurs, the first display electrode 6 and the second display electrode 8
There is little fluctuation in the voltage difference of, and constant display characteristics can be obtained.

[0128]

As is apparent from the above description, by using the configuration of the liquid crystal display device of the present invention, the viewing angle characteristics in the front-rear direction are improved while the front contrast is improved, and the halftone display is reversed. It is possible to provide a MIM type liquid crystal display device which is hard to occur and has a high contrast wide viewing angle characteristic.

Furthermore, even if there is over-etching or under-etching in the photo-etching process, the driving voltage difference between the plurality of display electrodes does not change so much that constant display characteristics are always obtained, and a liquid crystal display with stable display characteristics is obtained. A device can be provided.

[Brief description of drawings]

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

FIG. 2 is a sectional view showing a liquid crystal display device according to a first embodiment of the present invention.

FIG. 3 is a plan view showing a liquid crystal display device according to a second embodiment of the present invention.

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

FIG. 5 is a graph showing the relationship between applied voltage and transmittance when the liquid crystal display device is tilted forward by 40 °.

FIG. 6 is a plan view showing a liquid crystal display device in a conventional example.

FIG. 7 is a cross-sectional view showing a liquid crystal display device in a conventional example.

FIG. 8 is a graph showing the relationship between applied voltage and transmittance for explaining the viewing angle characteristics of the liquid crystal display device in the front-rear direction.

FIG. 9 is a plan view showing a liquid crystal display device in a conventional example.

[Explanation of symbols]

 1 1st board 2 1st electrode 3 Non-linear resistance layer 4 2nd electrode 5 1st non-linear resistance element 6 1st display electrode 7 2nd non-linear resistance element 8 2nd display electrode 9 Drive electrode 10th 2 substrate 11 counter electrode 12 alignment film 13 liquid crystal

Claims (5)

[Claims] 1. A first substrate having a non-linear resistance element including a first electrode, a non-linear resistance layer and a second electrode, a display electrode and a drive electrode, a second substrate having a counter electrode, and A liquid crystal to be sealed between a first substrate and a second substrate; one pixel is composed of one counter electrode, a plurality of display electrodes and a non-linear resistance element connected to each of the display electrodes, and each non-linear A liquid crystal display device, wherein the resistance elements have the same area and the display electrodes have different areas, and the capacitance ratio between the non-linear resistance element and the display electrode is different. 2. A first substrate having a non-linear resistance element including a first electrode, a non-linear resistance layer and a second electrode, a display electrode and a drive electrode, a second substrate having a counter electrode, A liquid crystal to be sealed between a first substrate and a second substrate, and one pixel is composed of one counter electrode, a plurality of display electrodes and a non-linear resistance element connected to each display electrode, and each display A liquid crystal display device, characterized in that the areas of the electrodes are the same, the areas of the non-linear resistance elements are different, and the capacitance ratios of the non-linear resistance elements and the display electrodes are different. 3. A first substrate having a non-linear resistance element including a first electrode, a non-linear resistance layer and a second electrode, a display electrode and a drive electrode, a second substrate having a counter electrode, and a first substrate.
And a liquid crystal sealed between the second substrate and a second substrate, and a plurality of different size non-linear resistance elements for connecting one pixel to one counter electrode, a plurality of display electrodes of different sizes, and each display electrode. And a non-linear resistance element with a small area is connected to the display electrode with a large area, a non-linear resistance element with a large area is connected to the display electrode with a small area, and the capacitance ratio between the non-linear resistance element and the display electrode is Liquid crystal display device characterized by different. 4. The second electrode provided on the first substrate is made of a transparent conductive film made of the same material as that of the display electrode, according to claim 1, 2, or 3. Liquid crystal display device. 5. The non-linear resistance element of the first substrate, or the non-linear resistance element of the first substrate and the display electrode,
An insulating film is provided, Claim 1, Claim 2,
The liquid crystal display device according to claim 3 or 4.