JPH0519274A - Liquid crystal element - Google Patents

Abstract

PURPOSE:To provide a liquid crystal element where the high density of a picture element is accomplished. CONSTITUTION:This liquid crystal element is provided with a transparent conductive substrate 1, an electrode supporting substrate 5a opposed to the substrate 1, and a liquid crystal layer 3 provided between both substrates. A picture element electrode 4a is formed on the surface of the substrate 5a on the liquid crystal layer side and a signal wiring path 6 allowing the picture element electrode 4a to actuate is formed on the surface on an opposite side thereto, then the electrode 4a and the wiring path 6a are allowed to mutually communicate through a through hole wiring path 8a which pierces the substrate 5a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal element useful in the fields of display, light control, color control and the like.

[0002]

2. Description of the Related Art A liquid crystal device having a structure in which transparent conductive films are formed on both surfaces of a liquid crystal / polymer composite film in which a low molecular weight nematic liquid crystal is microscopically dispersed in a polymer uses only a low molecular weight nematic liquid crystal. It was announced in 1985 because it has advantages of brighter and wider viewing angle, easier to see, easier to be flexible, because it does not require a polarizing plate, compared to conventional liquid crystal elements. Since then (see 1-3), research and development have been actively conducted.

1) Nikkei Microdevice, August 1985, p. 53, 2) Patent application publication number: Showa 58-501631
No., Publication date: September 29, 1983, Priority claim date: 1
September 16, 983 3) Fergason, JL, "Polymer Encapsulated Nematic Li
quid Crystalsfor Display and Light Control Applica
tions, "SID International Symposium Digest of Techni
cal Papers, pp.68-70, May 1985. This liquid crystal / polymer composite material (hereinafter abbreviated as “polymer composite liquid crystal”) has a PDLC structure in which the liquid crystal is discontinuously dispersed in a polymer medium due to the dispersion structure of the liquid crystal. polymer-di
spersed liquid crystal) and PN-LC in which liquid crystal exists continuously in polymer network (sponge)
It is classified into two types, (polymer network liquid crystal) (see Note 4 below).

4) Nikkei Electronics, June 11, 1990 (No. 502) Page 102 The polymer composite liquid crystal is normally in an opaque state, but becomes transparent when a voltage is applied. This polymer composite liquid crystal
If a dichroic dye is dissolved in this, it is possible to change from a colored opaque state to a colorless transparent state by applying a voltage. Since these operating principles are described in many documents (Notes 5 and 6 below), they will not be described in detail here.

5) Appl. Phys. Lett. Vol.48, pp.27 (19
86) 6) Survey material for display I (report by Electronic Materials Technical Committee)
March, 1990, Japan Electronics Industry Promotion Association 58-6
0, 64 to 65 Recently, Kajiyama et al. Have made a compound liquid crystal that is a blend of a high molecular liquid crystal and a low molecular nematic liquid crystal into an induced smectic liquid crystal, which becomes transparent under a high frequency electric field and becomes opaque under a low frequency electric field. It has been found that these states are stored in memory even when the power supply is turned off (see Note 7 to 9 below).

7) Chemistry Letters, pp.817-820 (19
89) 8) Polymer Preprints, Japan, vol.39, No.3, pp.761
(1990) 9) Polymer Preprints, Japan, vol.39, No.8, pp.2373
(1990) These composite liquid crystals are dimming, color adjusting,
It is being applied in fields such as displays.

Conventionally, the electrode pattern of a display element using liquid crystal has a segment electrode, a dot matrix electrode,
Matrix electrodes and comb-teeth electrodes are known, and as a driving method, a static driving method and a multiplex (time division) driving method are known. In the segment type and dot matrix type display elements, when the number of pixels is small, a static drive method in which all segment electrodes (pixel electrodes) are individually driven is adopted, but when the number of pixels increases, the electrode pattern generally becomes larger. The multiplex drive system is adopted regardless of the above. However, in the case of a polymer composite liquid crystal having a gradual gradient of the operation threshold characteristic, a crosstalk effect occurs, so that it is difficult to adopt it.

[0008]

Conventional segment-type and dot-matrix type display elements have a structure as shown in FIGS. 7 shows an example of a transmissive type, and FIG. 8 shows an example of a reflective type. Then, FIG. 9 shows pixel electrodes and signal wiring paths for driving each pixel electrode in these elements. In these figures, 1 is a transparent substrate, 2 is a transparent conductive (common) electrode, 3 is a polymer composite liquid crystal, 4 is a transparent conductive pixel (segment) electrode, 5 is a transparent electrode supporting substrate, 6 is a transparent conductive signal wiring path, 7 represents a colored reflector. As can be seen from FIG. 9, the pixel electrode 4 and the signal wiring path 6 are formed on the same surface (the surface on the liquid crystal layer 3 side) of the electrode supporting substrate 5. Therefore, in these conventional liquid crystal display elements, the signal wiring path 6 must pass between the adjacent pixel electrodes 4 and 4, and there is a problem in that the density of pixels cannot be increased.

Therefore, the present invention solves the above problems,
It is a first object to provide a liquid crystal element capable of increasing the density of pixels regardless of whether it is a reflective type or a transparent type.
In addition, a second object is to provide a liquid crystal element that can easily set and change the display pattern.

[0010]

In order to solve the first problem, the invention according to claim 1 is provided between a transparent conductive substrate, an electrode supporting substrate facing the transparent conductive substrate, and these two substrates. In a liquid crystal element including a liquid crystal layer, a pixel electrode is formed on the surface of the electrode supporting substrate on the liquid crystal layer side, and a signal wiring path for operating the pixel electrode is formed on the opposite surface. The pixel electrode and the signal wiring path are electrically connected to each other by a through hole wiring path penetrating the electrode supporting substrate.

In order to solve the second problem, a second aspect is provided.
The described invention is a liquid crystal element comprising an electrode supporting substrate facing the substrate and a liquid crystal layer provided between the two substrates, wherein the electrode supporting substrate has a pixel electrode on its liquid crystal layer side surface. The connection terminals of the respective pixel electrodes are formed independently on the opposite surface, and the pixel electrodes corresponding to the respective connection terminals are electrically connected to each other by a through-hole wiring path penetrating the electrode supporting substrate. It is characterized by

The transparent conductive substrate is usually one in which a transparent electrode is formed on the inner surface (the surface on the side of the liquid crystal layer) of the transparent substrate as in the conventional example, but if the transparent substrate itself has conductivity, Does not require transparent electrodes. In this case, examples of the transparent substrate include a glass plate, a transparent ceramics plate, a transparent resin film such as polyethylene terephthalate (PET) and polycarbonate, and a transparent plastic plate such as an acrylic plate and a polycarbonate plate.

As the electrode supporting substrate, a commonly used through-hole double-sided plate can be used. Since a double-sided copper clad laminate is often used as the through-hole double-sided plate, the material of the electrode is usually copper, but the material is not limited to this, and other metals such as aluminum and nickel are used. May be In the present invention, different metals may be used on both sides of the electrode supporting substrate. Such a through-hole double-sided board can be manufactured by a usual printed wiring board technique. As the substrate material, a substrate material used for general printed wiring boards can be used.
That is, a rigid substrate such as a paper phenol substrate, a paper epoxy substrate, a glass epoxy substrate, and a glass polyimide substrate, a semi-flexible substrate, and a flexible substrate such as a polyester film and a polyimide film can be used. Of course, a semi-flexible substrate may be used. According to the present invention, by selecting the materials of the transparent conductive substrate and the electrode supporting substrate, it is possible to manufacture from a rigid and flat liquid crystal device to a flexible or semi-flexible liquid crystal device capable of processing a curved surface. When the electrode supporting substrate needs to be transparent, the above-mentioned transparent substrate or the like is used as the substrate material.

The material of the pixel electrode, the signal wiring path, and the through-hole wiring path may be any material having good conductivity.
When the pixel electrode also serves as a reflector, a metal having high reflectance is preferable. In order to obtain a uniform display surface, it is preferable that the through-hole wiring path is formed by filling the through-hole with a material having good conductivity (Ag paste or the like) and forming a part of the pixel electrode. The through-hole wiring path is preferably transparent, but it may not necessarily be transparent depending on the application as long as its proportion to the pixel electrode is small.

As the transparent conductive electrode material, in addition to transparent semiconductors such as indium tin oxide (ITO) and tin oxide, there are metal thin films such as Au, Ag, Cu and Al. In the case of the second aspect of the invention, each pixel electrode is provided with an independent connection terminal, which is suitable for active matrix driving in which a voltage is independently applied to each pixel. When a large display or an advertisement display is performed, a power supply wiring line is connected to a connection terminal of a predetermined pixel electrode and a voltage is applied. However, in the liquid crystal element according to the invention of claim 2, the power supply wiring line according to the display pattern is formed. It can be easily formed and can be easily changed. Although the power supply wiring path connected to the connection terminal corresponding to the display pattern is provided on the surface of the electrode supporting substrate on the side where the connection terminal is formed, the power supply wiring path can be easily formed and changed. In this case, when a display pattern is not frequently changed, such as when displaying a predetermined pattern for a certain period of time such as in the case of an event and displaying another pattern in the next event. Useful for. The power supply wiring path can be easily realized by, for example, creating an electric path pattern corresponding to a display pattern at an actual size and attaching this to a connection terminal. Specifically, there are the following methods.

The power supply wiring path can also be easily realized by printing a commercially available conductive paste (mixture of conductive filler, binder, solvent and additive) in a predetermined electric path pattern. The conductive filler, silver powder, copper powder,
Nickel powder, graphite, carbon black, etc. are used. As the binder, a resin composition of epoxy, urethane, acrylic, alkyd, melamine, phenol or the like is used.

There is also a method of forming a predetermined electric circuit pattern using a conductive tape or a conductive foil (conductive sheet). A conductive tape or conductive foil with a conductive adhesive is used, and the conductive tape or conductive tape is adhered to the connection terminal with the conductive adhesive applied to the surface. In the case of a conductive adhesive, it can be easily removed and replaced with another power supply wiring path. In the case of the conductive foil, it is possible to cut out an electric circuit pattern that matches the display pattern and dispose it at once.

Further, by using the magnetic material, the power supply wiring path can be easily formed and changed. A multi-layer sheet (tape-shaped one) in which a magnetic material is used for at least a part of the connection terminal or a through hole is filled with a conductive magnetic material while a conductive tape or conductive foil is laminated with a permanent magnet layer. (Including also), the conductive tape or conductive foil is connected to the connection terminal by the magnetic force of the permanent magnet layer. Also in this case, if the conductive foil is notched in the electric path pattern that matches the display pattern, it can be arranged at one time, which is convenient. Further, in the case of a conductive foil, it is also possible to use a method in which a circuit pattern corresponding to a display pattern is cut out and pressed by a permanent magnet sheet via an insulating sheet.

The conductive magnetic material includes metals such as iron, cobalt and nickel and alloys thereof. Further, as the permanent magnet layer material, alnico magnet alloy, ferrite magnet material,
There are rare earth cobalt magnet materials, Fe-Cr-Co magnet materials and Pt-Co magnet materials. Be done. The above-mentioned multi-layer sheet in which a conductive layer and a permanent magnet layer are laminated (including a tape-shaped sheet)
Can be produced by bonding a conductive foil or a conductive tape to a so-called rubber magnet or plastic magnet sheet (including a tape-shaped sheet) obtained by blending these magnet materials with rubber or a thermoplastic or thermosetting resin.

A power supply wiring path can be easily realized by connecting a metal wire to a connection terminal corresponding to a display pattern by using a bander or a conductive adhesive. As the liquid crystal layer,
In addition to low-molecular nematic liquid crystals and ferroelectric liquid crystals, host-guest type liquid crystals in which a dichroic dye is dissolved can be used, but recently developed low-molecular nematic liquid crystals are discontinuous in a polymer matrix. As described above, polymer composite liquid crystals such as so-called PDLC and PN-LC dispersed in a continuous or continuous form are easy to have a large area and have flexibility, and since a polarizing plate is unnecessary, they are bright and have a wide viewing angle. It is preferably used because it is easy to see. The induced smectic liquid crystal obtained by blending the high molecular weight liquid crystal and the low molecular weight nematic liquid crystal can be more preferably used because it has the same advantage and has a memory property by being driven at two frequencies.

The liquid crystal element according to the present invention may be a reflection type element in which the electrode supporting substrate is an opaque substrate and the pixel electrode is made of a metal having a high reflectance, and the electrode supporting substrate is It may be a transmissive element which is a transparent substrate and in which the pixel electrodes and the signal wiring paths are made of a transparent material. However, in the case of the liquid crystal element of claim 2, as described above, the wiring is performed on the back side of the electrode supporting substrate, so that it is usually a reflective type.

As the reflection type display element, it is preferable to use a color liquid crystal in which a dichroic dye is blended with the liquid crystal because it is better to hide the underlayer so that the contrast is better, but the invention is not limited to this. In the reflective type, the surface of the pixel electrode may be polished to increase its reflectance,
It is effective for improving the contrast. Changing the reflection color from the pixel electrode is preferable for obtaining a color image for the reason of improving the contrast property. As the method of changing the reflection color, 1) change the material of the metal (only the surface layer may be changed by plating), 2) make a thin film on the surface and use the interference of light (the technology of color titanium), 3) )
For example, applying a colored paint to the surface. In this case, the pixel electrodes may have the same color as a whole or may have different colors for different colors.

In particular, in the case of the liquid crystal device according to the first aspect, it is useful to make the signal wiring paths multi-layered in order to further increase the density of the signal wiring paths. Such multi-layering can also be performed by a normal technique for producing a multilayer printed wiring board. In the display element using the liquid crystal element according to claim 1, the extraction terminal portions to the outside of the signal wiring path may be gathered at the end portions of the electrode supporting substrate and directly connected to the connector, or the DIP (dual in package) method. Alternatively, a PGA (pin grid array) method may be used. With this configuration, high-density wiring can be accommodated, and a large-screen display can be easily realized by using a large number of display element units for expansion.

The liquid crystal device according to claim 2 can be taken out in various ways, not limited to the above case. The above is a description of the liquid crystal element of the present invention by taking a display application as an example.
The use of the liquid crystal element according to the present invention is not necessarily limited to the display use, and may be the use such as light control and color control.

[0025]

In the liquid crystal element of the present invention, the signal wiring line and the power feeding wiring line are formed on the surface of the electrode supporting substrate opposite to the pixel electrodes, so that the signal wiring line and the power feeding wiring line are formed between the adjacent pixel electrodes. Since it is not necessary to pass through the path, the pixel electrodes can be brought close to each other, and the pixel density can be increased.

In the liquid crystal element of claim 2, in addition, the connection terminal is formed on the opposite surface of the electrode supporting substrate for each pixel electrode, so that the power supply wiring path can be easily formed according to the display pattern. Since it can be easily changed, it is easy to set and change the display pattern.

[0027]

EXAMPLES Examples of the present invention will be described below, but the scope of the present invention is not limited thereto. -Example of liquid crystal element according to claim 1-Fig. 1 shows an example of a reflective liquid crystal element according to the present invention. In the figure, 1 is a transparent substrate, 2 is a transparent common electrode, and these both constitute a transparent conductive substrate. Also,
3 is a polymer composite liquid crystal, 4a is a pixel electrode which also serves as a reflector, and 5
Reference numeral a represents an electrode supporting substrate, 6a represents a signal wiring path, and 8a represents a through hole wiring path. FIG. 2 shows an example of a transmissive liquid crystal element according to the present invention. Pixel electrode 4b, electrode support substrate 5b,
The signal wiring path 6b and the through-hole wiring path 8b are both transparent and have the same structure as that of the embodiment of FIG. FIG. 3 shows a pixel electrode 4a (4b) and a signal wiring path 6 for driving each pixel electrode in these two types of liquid crystal elements.
a (6b) is shown. As can be seen from FIG. 3, the signal wiring path 6a (6b) is formed on the surface of the electrode supporting substrate 5a (5b) opposite to the surface on which the pixel electrode 4a (4b) is formed (the surface on the liquid crystal layer 3 side). The pixel electrode 4a is formed so as to overlap the electrode 4a (4b) and is adjacent to the pixel electrode 4a.
It does not pass between (4b) and 4a (4b). Therefore, the distance between adjacent pixel electrodes is narrow. The terminal portion 9a (9b) of each signal wiring path 6a (6b) is gathered at the end portion of the electrode supporting substrate.

-Embodiment of Liquid Crystal Element According to Claim 2-FIG. 4 shows an example of a reflective liquid crystal element according to the present invention. In the figure, 1 is a transparent substrate, 2 is a transparent common electrode, and these both constitute a transparent conductive substrate. Also,
3 is a polymer composite liquid crystal, 4a is a pixel electrode which also serves as a reflector, and 5
Reference numeral a represents an electrode supporting substrate, 8a represents a through hole wiring path, and 10 represents a connection terminal. The size of the connection terminal 10 is smaller than the size of the pixel electrode 4a.

A double-sided copper clad laminate (epoxy laminate, plate thickness 1.6 mm) is used for the electrode support substrate 5a, and as shown in FIG. 5, a group of pixel electrodes 4a arranged vertically and horizontally on the surface is shown in FIG. As shown in 6, the connection terminal 1 is provided on the back surface for each pixel electrode 4a.
Group 0 was formed respectively. The group of pixel electrodes 4a is shown as 13 × 13 dots for convenience in FIG. 5, but 16 × 16 dots, 50 × 100 dots, and the like can of course be used. In this embodiment, 24 × 96 dots are used. Further, instead of using a single large display panel, small display units of 16 × 16 dots or 24 × 24 dots may be connected to form a single display panel.

The through hole has a diameter of 0.3 mm and was manufactured by an ordinary printed wiring board manufacturing process. Solder was filled into the through-hole holes that were electrolessly plated and electrolytically copper-plated to form through-hole wiring paths. The pixel electrode was roughened by chemical treatment and then electroless tin-plated to obtain a white diffuse reflector. To obtain a color display, the surface of the pixel electrode may be coated with a thin color ink.

In order to cover ordinary applications, the pixel electrode size is about 1 to 10 mm square, and the pixel electrode interval is 0.1 to 2 mm.
The degree is not limited to this. In this embodiment, the pixel electrode size is 5 mm square, and the pixel electrode interval is 1 mm. Also,
The connection terminal 10 is 3 mm square. The shape of the pixel electrode is a square in this embodiment, but may be another shape such as a rectangle, a rhombus, a circle or an ellipse.

In this example, a plurality of dichroic dyes were added to the polymer composite liquid crystal so as to give a black color in order to obtain a black and white display element. A copper foil tape having a back surface coated with a conductive adhesive was attached to the connection terminal 10 so as to form a predetermined electric circuit pattern. Further, an example in which the connection terminal 10 was plated with nickel (magnetic material) was prepared, and a tape-shaped multi-layer sheet in which copper foil was laminated and adhered to a plastic magnet sheet was used. When it was attached to the connection terminal 10 so as to be and actually driven, an appropriate display was made.

In order to facilitate the connection with the external electrode, the power supply connecting terminal 11 may be formed on the electrode supporting substrate 5a as shown in FIG.

[0034]

As described above in detail, in the liquid crystal element according to the present invention, the pixel electrode and the signal wiring path are formed separately on the front and back surfaces, not on the same surface of the electrode supporting substrate. Therefore, it is not necessary to pass the signal wiring path and the power feeding wiring path between the adjacent pixel electrodes, and it is possible to greatly increase the density of the pixels.

In the liquid crystal device according to the second aspect, in addition, since it is easy to form the power supply wiring path according to the display pattern and it is easy to change it, it is possible to set the display pattern.
It is very useful because it can be easily changed.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a liquid crystal element of the present invention that is a reflective type.

FIG. 2 is a cross-sectional view of a liquid crystal element of the present invention that is a transmissive type.

FIG. 3 is a plan view showing pixel electrodes and signal wiring paths of the liquid crystal element of the present invention.

FIG. 4 is a cross-sectional view of a liquid crystal element of the present invention that is a reflective type.

5 is a plan view showing a pixel electrode formation surface of the liquid crystal element of FIG.

6 is a plan view showing a connection terminal formation surface of the liquid crystal element of FIG.

FIG. 7 is a cross-sectional view of a conventional liquid crystal element that is a transmissive type.

FIG. 8 is a cross-sectional view of a conventional liquid crystal element that is a reflective type.

FIG. 9 is a plan view showing pixel electrodes and signal wiring paths of these conventional liquid crystal elements.

[Explanation of symbols]

1 transparent substrate 2 Transparent common electrode 3 Polymer composite liquid crystal 4a Pixel electrode that also serves as a reflector 4b transparent pixel electrode 5a electrode support substrate 5b Transparent electrode support substrate 6a Signal wiring path 6b Transparent signal wiring path 8a through hole wiring path 8b Transparent through hole wiring path 10 connection terminals

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Fumiaki Kobayashi             1048, Kadoma, Kadoma-shi, Osaka Matsushita Electric Works Co., Ltd.             Inside the company (72) Inventor Koji Takagi             1048, Kadoma, Kadoma-shi, Osaka Matsushita Electric Works Co., Ltd.             Inside the company

Claims (15)

[Claims] 1. A liquid crystal element comprising a transparent conductive substrate, an electrode supporting substrate facing the transparent conductive substrate, and a liquid crystal layer provided between the both substrates, wherein the electrode supporting substrate has a liquid crystal layer side. A pixel electrode is formed on the surface, and a signal wiring path for operating the pixel electrode is formed on the opposite surface,
A liquid crystal element, wherein the pixel electrode and the signal wiring path are electrically connected to each other by a through-hole wiring path penetrating the electrode supporting substrate. 2. A liquid crystal element comprising a transparent conductive substrate, an electrode supporting substrate facing the transparent conductive substrate, and a liquid crystal layer provided between the two substrates, wherein the electrode supporting substrate has a liquid crystal layer side. Pixel electrodes are formed on the surface, connection terminals for each pixel electrode are independently provided on the opposite surface, and pixel electrodes corresponding to each connection terminal are formed by a through-hole wiring path penetrating the electrode support substrate. A liquid crystal element, which is electrically connected to each other. 3. The liquid crystal device according to claim 1, wherein the electrode supporting substrate is an opaque substrate, and the pixel electrode is made of a metal having a high reflectance, which is a reflective device. 4. The liquid crystal device according to claim 1, wherein the electrode supporting substrate is a transparent substrate, and the pixel electrode and the signal wiring path are made of a transparent material. 5. The liquid crystal device according to claim 1, wherein the signal wiring path has a multilayer structure. 6. The through hole wiring path is made by filling a conductive material or a conductive magnetic material.
The liquid crystal device according to any one of 1 to 3 above. 7. The signal wiring path terminal is taken out by a pin grid array method, or claim 3.
7. The liquid crystal device according to any one of 1 to 6. 8. The liquid crystal element according to claim 2, wherein the connection terminal is formed directly behind the corresponding pixel electrode, and the size of the connection terminal is smaller than the size of the pixel electrode. 9. The liquid crystal device according to claim 2, wherein the connection terminal is formed of a conductive magnetic material. 10. The liquid crystal device according to claim 2, wherein a power supply wiring path connected to a connection terminal corresponding to a display pattern is provided on a surface opposite to the electrode supporting substrate. . 11. The liquid crystal device according to claim 10, wherein the power supply wiring path is formed of a metal wire, a conductive paste, a conductive tape, or a conductive foil. 12. The liquid crystal device according to claim 1, wherein the liquid crystal layer is a PDLC having a structure in which a low-molecular liquid crystal is dispersed in a polymer in a discontinuous manner. 13. The liquid crystal device according to claim 1, wherein the liquid crystal layer is a PN-LC having a structure in which low molecular weight liquid crystals are continuously present in a polymer network. 14. The liquid crystal device according to claim 1, wherein the liquid crystal layer is a smectic liquid crystal formed by mixing a high molecular liquid crystal and a low molecular liquid crystal. 15. The liquid crystal device according to claim 1, wherein the surface of the pixel electrode is colored in multiple colors.