JPH06208124A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To make the cell gap even over the whole surface of a liquid crystal cell to eliminate the lighting at a wiring part and the unevenness of contrast. CONSTITUTION:A pair of dummy electrodes 33, 34 are also provided at a wiring part 11 of a display area 10, and dummy electrodes 34, 44 respectively having the nearly same shape with the shape of dummy electrodes 34, 44 are provided in wiring electrodes 321, 421 near each electrode of the display area 10, and these dummy electrodes 34, 44 are electrically connected to each other at a seal part. Consequently, the dummy electrodes 34, 44, which are provided in an upper and a lower substrates, have the same electric potential to eliminate the lighting at the wiring part, and the cell gap is evened over the whole surface to improve the contrast.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and in particular, it is a large-sized so-called ST which is particularly sensitive in characteristics to variations in cell gap and which requires uniformity within a screen.
The present invention relates to an N dot matrix type liquid crystal display device.

[0002]

2. Description of the Related Art A dot matrix type liquid crystal display device of this type has an upper glass substrate and a lower glass substrate which are arranged to face each other with a liquid crystal interposed therebetween, and the surfaces of the upper glass substrate which come into contact with the liquid crystal are equidistant and parallel to each other. The formed striped upper transparent electrode group and the striped lower transparent electrode group formed on the surface of the lower glass substrate in contact with the liquid crystal at right intervals and in parallel to the upper transparent electrode group. By applying a voltage between the electrodes arranged via the liquid crystal, the alignment direction of the liquid crystal molecules at the intersections is changed and displayed as dots.

Regarding the driving technique of this type of liquid crystal display device, for example, “Applied Physics Letter” 45, No. 10, 1021, 1984 (Applied
Physics Letter, TJScheffer, J.Nehring: "A new hig
hly multiplexable liquidcrystal display ").

[0004]

In the conventional liquid crystal display device having the above structure, the gap between the transparent electrodes formed on each of the upper substrate and the lower substrate, that is, the cell gap is not uniform. Unevenness occurs and the display quality is degraded.

As one means for dealing with this problem, in Japanese Patent Application No. 4-52755 filed by the present applicant, in order to improve the cell gap uniformity, even in a portion where an electrically transparent electrode is not originally required. , A structure in which a dummy transparent electrode is provided to prevent nonuniformity of the cell gap due to the thickness of the transparent electrode is adopted.

FIG. 6 is a schematic plan view of a main part for explaining the structure of the above-mentioned conventional liquid crystal display device. 1 is an upper substrate (upper glass substrate), 2 is a lower substrate (lower glass substrate), and 3 is an upper substrate. Electrode (upper transparent conductive film), 4 lower electrode (lower transparent conductive film), 8 a sealing material forming a seal portion, 10 a display region, 11 a wiring portion, 31 an upper dummy electrode (upper dummy conductive film) , 32
Is an upper electrode terminal, 41 is a lower dummy electrode (lower dummy conductive film), and 42 is a lower electrode terminal.

FIG. 7 is a cross-sectional view of essential parts taken along the line aa in FIG. 6, and the same reference numerals as those in FIG. 6 correspond to the same parts, 6 is a liquid crystal, 9 is a parting plate, and 51 is a 51. Is an upper alignment film, 5
2 is a lower alignment film, 71 is a first spacer, and 72 is a second spacer.

6 and 7, the liquid crystal display device includes an upper electrode (segment electrode) 3 on the inner surface of the upper substrate 1, an upper alignment film 51 and a dummy electrode 21 coated thereon, and an inner surface of the lower substrate 2. The liquid crystal 6 in which the first spacers 71 are dispersed is sandwiched between the lower electrode (common electrode) 4 and the lower alignment film 52 coated thereon, and a sealing material is provided around the upper substrate 1 and the lower substrate 2. 8 and the second spacer 72 is mixed and sealed with a seal portion.

A first spacer 71 is provided in a cell gap between an upper alignment film 51 formed on the upper substrate 1 and a lower alignment film 52 formed on the lower substrate 2, and a dummy electrode 21 formed on the upper substrate. A second spacer 72 is arranged in the gap between the lower electrode 4 and the lower electrode 4 of the lower substrate 2.

The dummy electrode 21 is installed on the outer peripheral side of the parting plate 9, and normally, in order to eliminate the influence of the shadow of the parting plate 9 which has a tolerance and a position for assembling with the parting plate 9, the parting plate 9 is provided. The distance S between the display area and the display area is 2 to 3 mm.

Therefore, in this portion S, the film constitution of the liquid crystal display cell is not the same as that of the display region 10 and is thin by the thickness of the upper electrode 3.

Usually, in order to prevent the gap bulge in the central part of the liquid crystal cell, the cell internal pressure after the liquid crystal material is sealed is lower than the atmospheric pressure and is sealed in a negative pressure state.

FIG. 8 is a schematic diagram showing a state in which the cell gap of the above conventional liquid crystal display device is changed at atmospheric pressure. The portion 13 without the upper electrode 3 has a small cell gap, and the influence of this small cell gap. Extends to the outer edge of the display area, and thus a small cell gap at the outer edge of the display area causes a decrease in threshold voltage (small threshold voltage).

However, as a matter of course, an electric field is applied to one wiring electrode, so that if the dummy electrode is simply arranged to face the other substrate, only the display area should be turned on. Since there is a problem that the wiring portion is also turned on, the position where the dummy electrode is arranged is in the seal portion where the upper substrate 1 is bonded via the liquid crystal 6, or the display is effective when the liquid crystal module is mounted. It was limited to the part outside the area, that is, the part hidden by the so-called parting plate.

Further, at the installation position of the dummy electrode, there is still a plane distance from the display area, which is not sufficient to improve the uniformity of the cell gap.
Cell gap non-uniformity (small gap) is likely to occur at the outer peripheral edge of the display region, resulting in a decrease in the threshold voltage at the outer peripheral edge of the display region, which is higher than that at the central portion of the display region. There has been a problem that a part of the part has a frame-like shape and the contrast is lowered.

There is also a method in which a counter electrode is more positively provided outside the display dot portion and a non-selection voltage is always applied by an external circuit. There is an inconvenience that means is required and the cost is increased. An object of the present invention is to avoid the problems caused by providing the dummy electrode as described above up to the vicinity of the electrode of the display dot portion, and to adjust the electrode thickness without adding an external circuit such as the non-selective waveform generating means. An object of the present invention is to provide a liquid crystal display device that eliminates cell gap nonuniformity and improves display quality.

[0017]

In order to achieve the above object, the present invention provides a dummy electrode by electrically connecting the dummy electrode to a wiring portion which is arranged so as to face each other and to which an electric field is applied. The dummy transparent conductive film and the wiring portion are always kept at the same potential so that the wiring portion does not turn on unnecessarily.

The above-mentioned electrical connection means has an anisotropic conductive function in which conductive particles are mixed in the sealant so that the sealant has conductivity in the thickness direction but no conductivity in the plane direction. It adopts the configuration that it has.

That is, according to the present invention, the upper substrate 1 and the lower substrate 2 which are arranged to face each other with the liquid crystal 6 in between, and the surfaces of the upper substrate 1 facing the liquid crystal are formed at equal intervals and in parallel. A plurality of stripe-shaped upper electrodes 3 and the lower substrate 2
A plurality of stripe-shaped lower electrodes 4 which are formed at equal intervals and in parallel with each other on the surface facing the liquid crystal,
An upper alignment film 51 and a lower alignment film 52 that cover the upper electrode 3 and the lower electrode 4 and have a cell gap and are in contact with and face liquid crystal, and a peripheral edge between the upper substrate 1 and the lower substrate 2. At least a sealing material 8 mixed with a spacer for sealing the liquid crystal with the cell gap is interposed between the upper substrate and the lower substrate, and the upper electrode 3 and the lower electrode 4 cross each other. A wiring region 11 is formed in which a display region 10 is formed in a portion thereof and wiring electrodes for connecting the upper electrode and the lower electrode to external connection terminals 32 and 42 are formed around the upper substrate and the lower substrate from the display region. In the liquid crystal display element provided, the wiring part 11 has an upper wiring electrode and a lower wiring electrode, the inner surface of each substrate and a position near the display area from the line portion, and substantially the same as each wiring portion electrode of the wiring portion. Dummy electrode pair 33 43, the upper dummy electrode 34, which is provided so as to extend to the vicinity of the display region, has substantially the same shape as the wiring electrode of the upper electrode while facing the wiring electrode of the lower electrode with substantially the same shape. The lower dummy electrodes 44 are provided so as to face each other and extend to the vicinity of the display region.

Further, conductive particles 73 are mixed with the sealing material 8 in addition to the cell gap forming spacers 72, and wiring electrodes opposed by the conductive particles 73 and dummy electrodes formed on the upper substrate. 34 and the dummy electrode 44 formed on the lower substrate are electrically connected.

[0021]

In the above-described structure of the present invention, the dummy electrodes provided to face the electrodes of the wiring part independently of each other are:
Since the seal portion is electrically connected to the opposing wiring portion and both have the same potential, they do not light up.

With this, the dummy electrode can be disposed close to the display area inside the parting plate, and the entire liquid crystal display cell can have the same thickness as that of the display area. Results in a uniform cell gap (uniform liquid crystal layer thickness), and there is no uneven contrast as in the prior art.

[0023]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a plan view of an essential part for explaining an embodiment of a liquid crystal display device according to the present invention, in which 1 is an upper substrate, 2 is a lower substrate, 3 is an upper electrode (segment electrode), and 4 is a lower electrode. (Common electrode), 8 is a sealing material, 11 is a wiring portion, 32 is an electrode terminal of an upper electrode, 33 and 43 are dummy electrode pairs, 34 is an upper dummy electrode, and 44 is a lower dummy electrode.

FIG. 2 is a sectional view of an essential part taken along the line aa of FIG. 1 for explaining an embodiment of the liquid crystal display device according to the present invention, and the same reference numerals as those in FIG. 1 correspond to the same parts. , 9 is a parting plate, 10 is a display region, 51 is an upper alignment film, 52 is a lower alignment film, 71 is a first spacer, 72 is a second spacer,
73 is a conductive particle.

In FIG. 1 and FIG. 2, this liquid crystal display device is opposed to each other with a liquid crystal 6 in between, and an upper substrate 1 and a lower substrate 2 are provided.
And a plurality of stripe-shaped upper electrodes 3 formed at equal intervals and in parallel on the surface of the upper substrate 1 facing the liquid crystal, and the upper electrode on the surface of the lower substrate 2 facing the liquid crystal. A plurality of stripe-shaped lower electrodes 4 which are formed to intersect each other at equal intervals and in parallel, and the upper electrode 3 and the lower electrode 4 are provided.
An upper alignment film 51 and a lower alignment film 52 are provided so as to cover each of the above and have a cell gap and are in contact with and face the liquid crystal.

In addition, a sealing material 8 is interposed between the upper substrate 1 and the lower substrate 2 at a peripheral end portion and the liquid crystal 6 is mixed between the upper substrate and the lower substrate with a spacer having the cell gap. It is sealed.

A display area 10 is formed at the intersection of the upper electrode 3 and the lower electrode 4, and the upper electrode 3 and the peripheral portion of the upper substrate 1 and the lower substrate 2 extend from the display area 10 to the upper electrode 3. An upper wiring electrode 321 that connects the lower electrode 4 to the external connection terminals 32 and 42, respectively, and a wiring portion 11 in which the lower wiring electrode 421 is formed are provided.

On the upper wiring electrode 321 and the lower wiring electrode 421 of the wiring portion 11, the wiring portion electrode 321 of the wiring portion 11 is provided on the inner surface of each substrate and at a position near the display area 10 from the line portion 11. , 421 are provided with dummy electrode pairs 33, 43 having substantially the same shape, and the upper dummy electrodes are provided so as to extend in the vicinity of the display region 10 so as to face the wiring portion electrode 421 of the lower electrode 2 in substantially the same shape. 34, and a lower dummy electrode 44 that is provided so as to face the wiring portion electrode 321 of the upper electrode 3 in substantially the same shape and extend to the vicinity of the display region 10.

That is, the upper dummy electrode 34 and the lower dummy electrode 34 formed of a transparent conductive film having substantially the same shape as the wiring electrodes 321 and 421 connecting the segment electrodes formed of the transparent conductive film in the display region 10 and the external connection terminals 32 and 42, respectively. Dummy electrode 44
Are provided on the opposite substrates (upper substrate 1, lower substrate 2).

Further, the upper dummy electrode 34 and the lower dummy electrode 44 are arranged in the display area 1 from the seal portion made of the seal material 8.
In addition to the first spacer 71 for forming a cell gap dispersed inside the liquid crystal cell, the seal portion is formed to a position very close to 0, and plastic beads made of the same material as the first spacer 71 are used. A conductive second spacer 72 having a conductive metal plated on the surface is mixed. This second
As the spacer 72, one having an average particle diameter of about 15% larger than that of the first spacer 71 for forming the cell gap is used, and the mixing amount into the sealing material 8 is about 100 / mm ² .

With the above-mentioned structure, the entire liquid crystal cell can be made to have a uniform thickness without lighting the wiring portion, and the contrast due to the small gap at the outer edge of the display area, which has been a problem in the past, can be achieved. The unevenness can be eliminated.

Next, an embodiment of a liquid crystal display device using the liquid crystal display element according to the present invention will be described.

FIG. 3 is a developed perspective view for explaining the overall structure of a liquid crystal display device using a liquid crystal display element according to the present invention. The same reference numerals as those of the embodiment of the liquid crystal display element correspond to the same portions, and 60 is Liquid crystal display element, 61 is a birefringent member, 62
Is an upper polarizing plate, and 63 is a lower polarizing plate.

In the figure, the upper substrate 1 holding the liquid crystal 6 in between.
The rubbing directions of the upper alignment film 51 and the lower alignment film 52 are set so that liquid crystal molecules have a twisted spiral structure between the lower alignment film and the lower alignment film 2.

The orientation films 51 and 52 are subjected to orientation treatment by rubbing (rubbing) the surface of an organic polymer resin sheet such as polyimide in one direction with a cloth or the like.

The alignment directions of the upper alignment film 51 and the lower alignment film 52 intersect with each other in the range of 180 ° to 360 °, and are opposed to each other with a cell gap d. The sealing material 8 has a liquid crystal injection port in a part thereof, and liquid crystal is injected into the gap between the alignment films 51 and 52 of the upper electrode 1 and the lower electrode 2 from the liquid crystal injection port, and is sealed as described above. It

A birefringent member 61 for phase compensation is arranged on the upper substrate of the liquid crystal display cell 60 thus constructed, and an upper polarizing plate 62 and a lower polarizing plate 63 are provided above and below the liquid crystal cell 60. The liquid crystal display device is configured by being provided.

FIG. 4 is a partially cutaway perspective view showing the structure around the upper substrate when a color liquid crystal display device is constructed using the liquid crystal display device according to the present invention.
Is an upper substrate, 301 is an upper red electrode (red segment electrode), 3
02 is an upper green electrode (green segment electrode), 303 is an upper blue electrode (blue segment electrode), 511 is an upper alignment film, 512 is a smoothing layer, 513 is a red filter, 514 is a green filter, 5
Reference numeral 15 is a blue filter and 516 is a light shielding film.

In the figure, when a liquid crystal display device for color display is constructed, the upper electrodes are electrodes 301, 302, 303 for driving the three primary colors of red, green, and blue, and correspondingly, red, green , Blue three primary color filters 513, 514, 51
5 and the light shielding film 516, a smoothing layer 512 for ensuring the smoothness of the upper alignment film 511 is provided.

By forming the above-mentioned dummy electrodes on the upper substrate having such a structure, the entire surface of the liquid crystal cell can be made to have a uniform thickness without lighting the wiring portion, which is a problem in the conventional display area. It is possible to eliminate unevenness in contrast due to a small gap at the outer edge of the.

FIG. 5 is an exploded perspective view of a liquid crystal display device using the liquid crystal display device according to the present invention assembled as a module, and 60 is the liquid crystal display device described in FIG.
Reference numeral 1 is a printed circuit board on which an IC 62 for driving a liquid crystal display device is mounted, 63 is a frame-like body, 64 is a diffusion plate, 65 is a light guide plate, 66 is a cold cathode ray tube (backlight), and 67 is a reflection plate.

In the figure, a liquid crystal display element 60 having a printed circuit board 61 fixed thereto has a frame-shaped body 63 and a front frame (partition plate) 6.
8 and the cold cathode ray tube 66 and the light guide plate 6 provided on the back surface.
5, integrated with the reflection plate 67 and the diffusion plate 64.

In such a structure, the cold cathode ray tube 66
The light from is directed toward the liquid crystal display element by the reflection plate 67, the light guide plate 65, and the diffusion plate 64, and is driven by the IC 62 or the like to pass to the front side by the twist of the liquid crystal molecules formed in the display area of the liquid crystal cell. As a result, an image or the like is reproduced in the liquid crystal display area.

This type of liquid crystal display module is used as an image output means for personal computers, word processors, and other information equipment.

[0046]

As described above, according to the present invention,
Even if a dummy electrode is arranged in the wiring part of the liquid crystal display element, the entire liquid crystal cell can be made to have a uniform thickness without being lit, and the small gap at the outer edge of the display dot part, which was a conventional problem, It is possible to provide a liquid crystal display element having excellent quality while avoiding uneven contrast.

[Brief description of drawings]

FIG. 1 is a plan view of relevant parts for explaining an embodiment of a liquid crystal display device according to the present invention.

FIG. 2 is a cross-sectional view of an essential part taken along line aa of FIG. 1 for explaining an embodiment of the liquid crystal display device according to the present invention.

FIG. 3 is a developed perspective view illustrating the overall structure of a liquid crystal display device using a liquid crystal display element according to the present invention.

FIG. 4 is a partially cutaway perspective view illustrating a configuration around an upper substrate when a color liquid crystal display device is configured using the liquid crystal display element according to the present invention.

FIG. 5 is an exploded perspective view in which a liquid crystal display device using the liquid crystal display element according to the present invention is assembled as a module.

FIG. 6 is a schematic view of a main part plane for explaining a configuration of a conventional liquid crystal display element.

FIG. 7A of FIG. 6 for explaining the configuration of a conventional liquid crystal display element.
It is a principal part sectional drawing cut | disconnected along the -a line.

FIG. 8 is a schematic view showing a state in which the cell gap of a conventional liquid crystal display element changes at atmospheric pressure.

[Explanation of symbols]

 1 Upper Substrate 2 Lower Substrate 3 Upper Electrode (Segment Electrode) 4 Lower Electrode (Common Electrode) 8 Sealing Material 9 Parting Plate 10 Display Area 11 Wiring Section 31 Upper Dummy Electrode 32 Upper Electrode Terminal 33,43 Dummy Electrode Pair 34 Upper Dummy Electrode 44 Lower dummy electrode 51 Upper alignment film 52 Lower alignment film 71 First spacer 72 Second spacer 73 Conductive particles.

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[Procedure amendment]

[Submission date] November 9, 1993

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 2

[Correction method] Change

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[Fig. 2]

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 7

[Correction method] Change

[Correction content]

[Figure 7]

[Procedure 3]

[Document name to be corrected] Drawing

[Correction target item name] Figure 8

[Correction method] Change

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[Figure 8]

Claims (2)

[Claims] 1. An upper substrate and a lower substrate which are arranged to face each other with a liquid crystal interposed therebetween, and a plurality of stripe-shaped upper electrodes which are formed in parallel on the surface of the upper substrate facing the liquid crystal at equal intervals. A plurality of stripe-shaped lower electrodes formed on the surface of the lower substrate facing the liquid crystal, at equal intervals and in parallel with the upper electrode group, and a cell covering each of the upper electrode and the lower electrode. An upper alignment film and a lower alignment film that are in contact with and face liquid crystal with a gap, and the liquid crystal is interposed between the upper substrate and the lower substrate by interposing a peripheral edge between the upper substrate and the lower substrate. At least a sealing material mixed with a spacer that seals with a cell gap is formed, and a display region is formed at a portion where the upper electrode and the lower electrode intersect with each other, and the display region is provided around the upper substrate and the lower substrate. The upper electrode and the lower electrode above are external In a liquid crystal display element having a wiring portion formed with a wiring electrode connected to a connection terminal, an upper wiring electrode and a lower wiring electrode of the wiring portion, the inner surface of each substrate and a position near the display area from the line portion. A dummy electrode pair of substantially the same shape is provided on each of the wiring part electrodes of the wiring part, and the dummy electrode pair is provided so as to face the wiring part electrode of the lower electrode in substantially the same shape and extend to the vicinity of the display region. A liquid crystal display device comprising: a dummy electrode; and a lower dummy electrode that is provided so as to face the upper electrode wiring portion electrode in substantially the same shape and extend to the vicinity of the display region. 2. The dummy formed on the upper substrate according to claim 1, wherein conductive particles are mixed with the sealing material in addition to the cell gap forming spacers, and the wiring electrodes are opposed to each other by the conductive particles. A liquid crystal display element, characterized in that an electrode and a dummy electrode formed on the lower substrate are electrically connected.