JPH05232490A - Liquid crystal element - Google Patents

Abstract

PURPOSE:To provide the liquid crystal element with which a higher density is obtainable and which has sufficient visibility. CONSTITUTION:This liquid crystal element is constituted by forming transparent electrodes 4 on one surface of an insulating substrate 5 and at least either of signal wiring lines 6 and connecting terminals on the opposite surface thereof, respectively, connecting the transparent electrodes 4 and at least either of the signal wiring lines 6 and the connecting terminals to each other by conductive paths 8 penetrating the insulating substrate 5 and installing a transparent electrode substrate 1 via a liquid crystal layer 3 on the side of the insulating substrate 5 opposite from the transparent electrodes 4. At least the transparent electrode forming region on one surface of the insulating substrate 5 is formed as a white color surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflective liquid crystal element.

[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 the advantages that it is brighter and has a wider viewing angle because it does not require a polarizing plate, is easier to view, and has flexibility 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 gazette number: Showa 58-501631
No., Publication date: September 29, 1983, Priority claim date: 1
September 16, 983 3) Technical report [Fergason, JL, "Polymer Encapsulate
d Nematic Liquid Crystals for Display and Light Con
trol Applications, "SID International Symposium Dige
st of Technical Papers, pp.68-70, May 1985. This liquid crystal / polymer composite material (hereinafter abbreviated as “polymer composite liquid crystal”) has a liquid crystal dispersed structure in which the liquid crystal is discontinuously dispersed in a polymer medium. PDLC (polymer-di
spersed liquid crystal) and PN-LC in which liquid crystal exists continuously in polymer network (sponge)
(Polymer network liquid crystal) (see Note 4 below).

4) Nikkei Electronics, June 11, 1990 (No. 502) p. 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) Magazine "Applied Physics" Appl. Phys. Lett.
vol.48, pp.27 (1986) 6) Survey materials for display I (report by Electronic Materials Technical Committee)
March 1990, Japan Electronics Industry Promotion Association 58-6
Page 0, 64-65 Recently, Kajiyama et al. Have made a compound liquid crystal, which is a blend of polymer liquid crystal and low molecular weight nematic liquid crystal, an induced smectic liquid crystal, which becomes transparent under high frequency electric field and becomes opaque under 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 Letter Chemistry Le
tters, pp.817 ~ 820 (1989) 8) Polymer Preprints, Jap
an, vol.39, No.3, pp.761 (1990) 9) Polymer Preprints, Jap
an, vol.39, No.8, pp.2373 (1990) These composite liquid crystals have dimming, toning, and
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 gentle slope of the operation threshold characteristic, a crosstalk effect occurs, and thus it is difficult to adopt it.

In the case of a liquid crystal element, there are a reflective type and a transmissive type. In the case of a reflective liquid crystal element, light entering from the incident surface is reflected on the back surface side of the liquid crystal layer and returns to the front surface side, which has a wide range of use and is highly practical.
FIG. 25 shows the pixel electrodes 4 and the signal wiring paths 6 for driving the pixel electrodes 4 in the conventional segment type and dot matrix type reflective liquid crystal display elements. Figure 2
5, the pixel electrode 4 and the signal wiring path 6 are formed on the same surface of the insulating substrate 5 (the surface on the liquid crystal layer side). Therefore, in the conventional liquid crystal display element, the signal wiring path 6 has to pass between the adjacent pixel electrodes 4 and 4, and there is a problem that the density of the pixels cannot be increased.

[0009]

Therefore, the inventors have
By studying from various angles, we devised a reflective liquid crystal device that can achieve high pixel density. That is, the signal wiring path is formed on the surface opposite to the surface on which the electrode is formed, and the two are connected by a conductive path penetrating the substrate. Since it is not necessary to provide the signal wiring path on the same surface as the pixel electrode, the density of pixels can be increased.

However, the liquid crystal element proposed by the inventors has not been sufficiently visible. If the visibility is not good, it is hard to say that it is highly practical. When a voltage is applied between the pixel electrode 4 and the transparent electrode of the transparent electrode substrate, the contact area of the pixel electrode 4 in the liquid crystal layer becomes transparent, and the incident light is reflected by the surface of the pixel electrode 4 and returns. for that reason,
On the screen of the liquid crystal element, a display having a shape corresponding to the planar shape of the pixel electrode 4 appears. However, in the conventional case, since the amount of light reflected and returned is small, the display lacks sharpness. That is, only a display with low contrast is displayed, and the visibility is not good. Even if the surface of the pixel electrode 4 is roughened to increase the diffusivity, the reflectivity is not improved so much.

In view of the above circumstances, it is an object of the present invention to provide a liquid crystal element which has high visibility and sufficient visibility.

[0012]

In order to solve the above problems, a liquid crystal element according to the present invention has a transparent electrode formed on one surface of an insulating substrate and at least one of a signal wiring path and a connection terminal formed on the opposite surface thereof. The transparent electrode and at least one of the signal wiring path and the connection terminal are connected to each other by a conductive path penetrating the insulating substrate, and a transparent electrode substrate is provided on a side of the insulating substrate opposite to the transparent electrode with a liquid crystal layer. In addition to the configuration in which the transparent substrate is formed through the above, at least the transparent electrode formation region of one surface of the insulating substrate is a white surface.

The transparent conductive substrate is usually one in which a transparent electrode is formed on the inner surface (the surface on the liquid crystal layer side) 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 a transparent electrode material, an ITO film (indium oxide-tin oxide) or a Nessa film (tin oxide) is suitable.

The insulating substrate on which the transparent electrodes for pixels are formed is one of the surfaces on the transparent electrode forming side of the insulating substrate.
At least the transparent electrode formation region is a white surface. The transparent electrode non-formed area does not have to be a white surface because the liquid crystal layer is always opaque, but the transparent electrode unformed area may be a white surface. For example, a white insulating substrate may be used not only on the entire surface but also on the inside, such as an alumina substrate. Further, the surface of a substrate material used for a general printed wiring board may be provided with a white coating layer to form a white surface. In the case of a laminated plate, a white prepreg may be used as the uppermost layer. As for the degree of whiteness of the white surface, the reflectance is 400 nm to 800 nm.
In the entire wavelength range of 70% or more, a flat spectral characteristic with 70% or more and minimal fluctuation is listed.

Specific substrate materials include ceramic substrates such as alumina substrates, rigid substrates such as paper phenol substrates, paper epoxy substrates, glass epoxy substrates and glass polyimide substrates, semi-flexible substrates, polyester films and polyimides. A flexible substrate such as a film can be used. Of course, a semi-flexible substrate may be used. According to the present invention, by selecting materials for the transparent conductive substrate and the insulating substrate, a rigid and flat liquid crystal element to a flexible or semi-flexible liquid crystal element that can be curved can be manufactured.

A transparent electrode for a pixel is formed on the white surface of the insulating substrate. This transparent electrode is, of course, made of a conductive material, and for example, a transparent conductive film such as an ITO film or a nesa film is used. Usually, an ITO film or a NES film is formed on a white surface of an insulating substrate, and then photo-etching or patterning using a laser beam is performed to obtain a predetermined shape. The ITO film can be formed on the insulating substrate by vapor deposition, sputtering or the like. The nesa film can be formed by spraying an aqueous solution containing tin chloride onto a heated insulating substrate. IT
It is easier to obtain an O film having higher transparency than a Nesa film, which is suitable for a liquid crystal element.

As the insulating substrate with the transparent electrodes, the signal wiring paths, the connection terminals, and the conductive paths, specifically, an ordinary insulating board having a through-hole double-sided plate can be used. Such a through-hole double-sided board can be manufactured by a usual printed wiring board technique. The through-hole wiring path connects the transparent electrode to the signal wiring path and the connection terminal. Further, in order to further increase the density of the signal wiring paths, it is useful to make the signal wiring paths multilayer. Such multi-layering can also be performed by a general technique for producing a multilayer printed wiring board.

The signal wiring paths and connection terminals are made of the same material as the transparent electrode, as well as metal materials such as copper, aluminum and nickel.
Alternatively, it may be formed of a conductive material such as a conductive paste. For example, a copper layer having a thickness of about 18 to 36 μm is exemplified, but the thickness is not limited to this. Normally, resist coating,
Patterning is performed by selective etching or the like to form a signal wiring path or a connection terminal having a predetermined shape.

Examples of materials for the through-hole wiring path include copper, tin, solder and gold. For example, a base metal film is formed by electroless plating, and a metal film having a sufficient thickness (for example, several tens of μm) is further laminated by electroplating to form a through-hole wiring path. It is preferable that the holes for through holes are filled with a material having good conductivity (Ag paste or the like) in order to obtain a uniform display surface.

When each transparent electrode serving as a pixel electrode is provided with an independent connection terminal, it is suitable for active matrix driving in which a voltage is independently applied to each pixel. When a large display or advertisement display is performed, a voltage is applied by connecting a power supply wiring path to the connection terminal of a predetermined transparent electrode, but when an independent connection terminal is provided for each transparent electrode, it is adjusted according to the display pattern. The power supply wiring path can be easily formed and its change can be easily performed. Although the power supply wiring path connected to the connection terminal corresponding to the display pattern is provided on the surface of the insulating substrate on which the connection terminal is formed, the power supply wiring path can be easily formed and changed. This is very useful when the display pattern changes infrequently, such as when displaying a certain pattern for a certain period of time such as in the case of an event and displaying another pattern at 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 it 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 a conductive foil, it is possible to dispose the conductive foil by cutting it out into an electric circuit pattern that matches the display pattern and arranging it at one time.

Further, by using the magnetic material, the power supply wiring path can be easily formed and changed. A multilayer 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. In the case of (including also), the conductive tape or conductive foil is connected to the connection terminal by the magnetic force of this 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 the conductive foil, it is also possible to use a method in which a notch is formed in an electric circuit pattern that matches the display pattern, and the permanent magnet sheet is pressed through the 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 prepared 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 banding 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 mentioned above, polymer composite liquid crystals such as so-called PDLC and PN-LC dispersed in a continuous or continuous form are easy to increase in 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 used more preferably because it has the same advantages and has a memory property by being driven at two frequencies.

2 used in the liquid crystal layer of the liquid crystal device of the present invention
Examples of the colorant include anthraquinone-based, azo-based, quinophthalone-based, perylene-based, coumarin-based, and thioindigo-based compounds used in fiber disperse dyes and the like. Specifically, the following chemical formulas (1) to (3)
Compounds of are exemplified. The one represented by the chemical formula (1) is yellow to orange, the one represented by the chemical formula (2) is red to purple, and the one represented by the chemical formula (3) is blue to sky blue. When producing a black color, a plurality of compounds are used in combination.

[0027]

[Chemical 1]

[0028]

[Chemical 2]

[0029]

[Chemical 3]

In the case of a reflection type liquid crystal element, it is preferable to use a color liquid crystal in which a dichroic dye is blended with the liquid crystal because the contrast is better when the base is hidden, but the invention is not limited to this. Next, the production of a through-hole wiring board that can be used in the liquid crystal element of the present invention will be specifically described.

First, as shown in FIG. 6, a through hole 31 is formed in an alumina substrate (insulating substrate) 5 whose both surfaces are white. The holes are formed by using, for example, punching processing or laser processing. Then, as shown in FIG. 7, a recess 32 for a conductive land is formed in the opening peripheral edge of the hole 31 on the surface on which the transparent electrode is formed. The recess 32 can also be formed by using laser processing or the like. The thickness of the alumina substrate 5 is, for example, about 1 mm, the diameter of the hole 31 is about 0.35 mm, and the recess 3 is formed.
The diameter of 2 is about 0.60 mm.

Following the processing of the recess 32, a copper film 33 is formed on both surfaces of the alumina substrate 5 and the inner surface of the hole 31, as shown in FIG.
To form. The copper film on the inner surface of the hole 31 is, of course, the through-hole wiring path 8. The copper film 33 can be formed by performing electroless copper plating and then electrolytic copper plating. After the through-hole wiring path 8 is formed, as shown in FIG. 9, the through-hole 31 is filled with the burying material 35 so that the through-hole wiring path 8 is not damaged in the etching process, and then the resist films 36 and 37 are formed. It is formed on the copper film 33. The resist film may be a commonly used one such as a solution or a film. Then, as shown in FIG. 10, the resist film 36,
37 is developed and selectively etched to form etching masks 38 and 39 that cover only necessary portions, and then etching is performed to remove unnecessary portions of the copper film to form a predetermined pattern. The copper film 33 remaining on the back surface of the alumina substrate 5 is a signal wiring path or a connection terminal. The copper film 33 remaining on the surface of the alumina substrate 5 is a conductive land.

Finally, as shown in FIG. 11, a transparent conductive film is formed on the surface of the alumina substrate 5 (for example, an ITO film is formed by vapor deposition or sputtering), and a predetermined pattern is formed using a resist mask or the like. Then, the transparent electrode 4 serving as a pixel electrode is formed. A colored layer may be provided on the front surface or the back surface of the transparent electrode 5 to form a color electrode structure.

As shown in FIG. 14, when the colored layer 15 is provided on the back surface of the transparent electrode 5, the colored layer is formed by a printing method or the like in the same pattern as the transparent electrode before forming the transparent electrode. Transparent electrode 4 is formed by forming a transparent conductive film and patterning
To form. However, whether the colored layer 15 has conductivity,
It is preferable that the colored layer 15 be provided with a hole so that the transparent electrode 4 is connected to the through hole wiring path 8 through the hole. Otherwise, the driving voltage will be high.

Further, as shown in FIG. 15, when the colored layer 15 is provided on the surface of the transparent electrode 5, the colored layer 15 is formed on the transparent electrode 4 in the substantially same pattern by a printing method or the transparent electrode 4 is formed. The colored layer 15 is formed by electrodeposition or electrolytic polymerization using the electrode as an electrode.
To form. Also in this case, the colored layer 15 is preferably conductive. In the case of electrodeposition method or electrolytic polymerization method,
A voltage can be applied to the transparent electrode 4 through the through hole wiring path 8.

Printing, electrodeposition, or electrolytic polymerization is performed in plural times, and the color and position of the colored layer are changed each time, and the colored layers of the transparent electrodes on the same insulating substrate are different in the transparent electrodes from each other. You can easily change the color.
A so-called RGB full-color configuration can also be used. It is also possible to simply form colored layers of the same color on all the transparent electrodes at the same time to form a monochromatic (single color) structure. The printing method includes lithographic printing, gravure printing, screen printing and the like using ink, and the electrodeposition method includes cation electrodeposition or anion electrodeposition.

It is preferable that the colored layer contains a fluorescent dye, a fluorescent pigment, or another fluorescent substance and has fluorescence, because fluorescence is added to the reflected light. Further, instead of providing the copper film for land, the conduction between the transparent electrode 4 and the through-hole wiring path 8 may be ensured as follows. That is, in the process of FIG. 7, instead of forming the recess for land in the hole 31 for through hole, as shown in FIG. 12, the linear taper 3 which is divergent toward the transparent electrode formation surface side is formed.
1a so that the transparent electrode 4 comes into contact with the through hole wiring path 8 at the taper 31a portion, or as shown in FIG.
If b is added and the transparent electrode 4 contacts the through-hole wiring path 8 at the taper 31b portion, the contact area is increased and the connection between the transparent electrode 4 and the through-hole wiring path 8 is ensured. Of course, in addition, holes 3 for through holes
1 may be filled with an embedding material.

In the display element using the liquid crystal element of the present invention,
The output terminal portion of the signal wiring path to the outside may be gathered at the end portion of the insulating substrate and directly connected to the connector,
A DIP (dual in package) system or a PGA (pin grid array) system may be used. In this way, high-density wiring can be accommodated, and a large screen display can be easily realized by expanding with a large number of display element units.

Although the liquid crystal element of the present invention has been described above by taking the display application as an example, the application of the liquid crystal element according to the present invention is not necessarily limited to the display application.

[0040]

In the liquid crystal element of the present invention, since the transparent electrode for the pixel and the signal wiring line and the power feeding wiring line are formed separately on one surface and the other surface of the same insulating substrate, the signal between the adjacent transparent electrodes is reduced. Since it is not necessary to pass the wiring path or the power feeding wiring path, the transparent electrodes for pixels can be brought close to each other,
It is possible to increase the density of pixels.

When the connection terminal is formed on the opposite surface of the insulating substrate for each transparent electrode, the power supply wiring path can be easily formed in accordance with the display pattern, and its change can be easily made. Easy setting and changing of patterns. In the liquid crystal element of the present invention, when the liquid crystal layer 3 is made of a polymer dispersed liquid crystal containing a dichroic dye, a voltage is applied between the transparent electrode 2 and the pixel transparent electrode 4 as shown in FIG. When not present, the liquid crystal layer 3 is opaque, and as shown in FIG. 17, when a voltage is applied between the transparent electrode 2 and the transparent electrode 4, the liquid crystal layer 3 becomes transparent. When it is made transparent, the light entering from the front surface of the transparent substrate 1 is reflected on the back surface side of the liquid crystal layer 3 and returns to the front surface again.

In the liquid crystal element of the present invention, the transparent electrode 4 is formed on the white surface of the insulating substrate 5. When there is no colored layer on the front and back surfaces of the transparent electrode 4, when the liquid crystal layer 3 becomes transparent, incident light passes through the transparent electrode 4 and is reflected by the white surface of the insulating substrate 5 and again passes through the transparent electrode 4 and the surface of the transparent substrate 1. Come back to. Since the white surface has a high reflectance and hardly absorbs the light incident through the transparent electrode 4, a large amount of light is reflected and returned. Therefore, a clear white display having the same shape as the planar shape of the transparent electrode appears on the screen of the liquid crystal element of the present invention.

Further, even when the transparent electrode 4 has a colored layer on the front surface or the back surface thereof, the white surface does not lose the physical properties as a white system, that is, the uniform and high reflectance characteristic. In this way, since the white surface of the insulating substrate 5 has a high reflectance characteristic, incident light passing through the colored layer and the transparent electrode 4 returns to the incident side without being absorbed by the insulating substrate 5. Therefore, a bright color tone (high lightness) is displayed on the screen of the liquid crystal element. Further, since the uniformity of the reflectance characteristics is maintained without being lost, the color expression by the colored layer is not affected by the influence of the insulating substrate. Therefore, an appropriate color display will appear on the screen. Also, regarding the type of display color,
When the colored layer is formed, it is possible to make the colorant suitable by selecting a colorant capable of producing a color suitable for the display purpose.

When the insulating substrate 5 has a white surface, since the insulating substrate 5 has a certain thickness, not only when the entire insulating substrate is white, but also when a white coating layer is provided. Since the thickness of the coat layer can be sufficiently secured, the back side of the white surface is not transparent,
It is possible to easily secure the physical properties as a white system that is uniform and has high reflectance characteristics.

When the transparent electrode forming surface of the insulating substrate 5 is not a white surface, the surface of the insulating substrate 5 absorbs incident light, and the amount of light reflected and returned is small, so that the display is not clear. Since the color of the colored layer is overlapped with the color of the surface of the insulating substrate, the expression of the color by the colored layer is impaired, so that the display is not an appropriate color. On the transparent electrode formation surface of the insulating substrate, there is a conductive land connected to the through hole wiring path,
A transparent electrode is formed on the conductive land, or a hole for a through hole is tapered toward the transparent electrode forming surface side, and the transparent electrode contacts the through hole wiring path at the tapered portion. In such a case, the contact area between the transparent electrode and the through-hole wiring path is substantially wide and the connection is ensured.

[0046]

EXAMPLES Examples of the present invention will be described below, but the scope of the present invention is not limited thereto. First, a basic configuration example of the liquid crystal element of the present invention will be described. —Structure Example A— FIG. 1 shows a reflective liquid crystal element according to Structure Example A. In the figure, 1 is a transparent substrate, 2 is a transparent common electrode, and these both constitute a transparent electrode substrate. Also,
3 is a polymer composite liquid crystal layer, 4 is a transparent electrode for pixels, 5 is an insulating substrate, 6 is a signal wiring path, and 8 is a through-hole wiring path. FIG. 2 shows the transparent electrode 4 in the liquid crystal element of Structural Example A.
And a signal wiring path 6 for driving each transparent electrode 4. As can be seen from FIG. 2, the signal wiring path 6 is formed so as to overlap the transparent electrode 4 on the surface of the insulating substrate 5 opposite to the surface on which the transparent electrode is formed (the surface on the liquid crystal layer 3 side), and is adjacent to the transparent electrode 4. It does not pass between the transparent electrodes 4 and 4.
Therefore, the distance between adjacent transparent electrodes for pixels is narrowed. The terminal portion 9 of each signal wiring path 6 is connected to the insulating substrate 5
Are gathered at the end of. Needless to say, the transparent electrode forming surface of the insulating substrate 5 is a white surface.

-Structural Example B- FIG. 3 shows a reflective liquid crystal element according to Structural Example B. 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 layer, 4 is a transparent electrode for pixels, 5 is an insulating substrate, 8 is a through-hole wiring path, and 10 is a connection terminal. The size of the connection terminal 10 is smaller than the size of the transparent electrode 4. Further, a copper foil tape (not shown) having a back surface coated with a conductive adhesive is attached to the connection terminal 10 so as to form a predetermined electric path pattern. Further, in order to facilitate the connection with the external electrode, as shown in FIG. 5, the power supply connection terminal 11 is formed on the back surface of the insulating substrate 5.

Not only in the configuration example B but also in the configuration example A, in the insulating substrate 5, as shown in FIG. 4, the transparent electrodes 4 for pixels arranged in order in the vertical and horizontal directions are provided on the surface. As shown in FIG. 5, the connection terminal 10 (the signal wiring path 6 in the case of the configuration example A) is formed on the back surface for each transparent electrode 4. For the sake of convenience, the group of transparent electrodes 4 is 1 in FIG.
3x13 dots, 16x16 dots, 50x1
Others such as 00 dots can of course be used. In this embodiment, 24 × 96 dots are used. Also, instead of using a single large display panel, 16 x 16 dots, or 2
You may connect small display units of 4 × 24 dots into one display panel.

The through-hole wiring path has a diameter of about 0.3 to 0.5 mm and was manufactured by an ordinary printed wiring board manufacturing process. Solder was filled into the through-holes that were electrolessly plated and electroplated. In addition, it goes without saying that a colored layer may be provided on the front surface or the back surface of the transparent electrode 4 in both the configuration examples A and B.

To cover normal applications, the transparent electrode 4
Size is about 1 to 10 mm square, and transparent electrode spacing is 0.1 to
It is about 2 mm, but not limited to this. For example, the transparent electrode size is 5 mm square, the transparent electrode interval is 1 mm, and the connection terminal 10 is 3 mm square. The shape of the transparent electrode may be other than square, such as rectangle, rhombus, circle, and ellipse.

-Example 1- Example 1 is a liquid crystal device of structural example A. The through-hole wiring board which is important in the construction of the present invention is as follows. First, a 1.0% thick 96% alumina substrate is used as an insulating substrate, and conductive lands are connected to the front surface, signal wiring paths are connected to the back surface, and conductive lands and signal wiring paths are connected to the inside of the substrate as shown in FIG. 6 and below. A through hole wiring path is formed.

Then, an ITO film having a thickness of 1000 liters was formed on the land forming surface by sputtering, a resist mask was formed and etching was performed to form a transparent electrode made of ITO. A spectral reflection characteristic (spectral reflection spectrum) measured by applying incident light to the surface of the transparent electrode of this through-hole wiring board is shown by a solid line in FIG. For spectral reflectance characteristics, use a standard spectrophotometer UV-350 (manufactured by Shimadzu Corp.)
(Daylight). Also, color / chromaticity meter CR-200
The reflectance and the three-dimensional coordinates (L, a, b) at a specific wavelength (see Table 1) were measured with (Minolta). Table 1 shows the measurement results
Shown in. L is an index showing lightness, and a and b are indexes showing hue.

Example 2-Using the through-hole wiring board obtained in Example 1, covering the signal wiring path forming side with a mask, immersing in the electrodeposition liquid consisting of red pigment and resin, and using the signal wiring path Apply voltage, current
The time was controlled to deposit the film on the transparent electrode.
Then, it is the same as Example 1 except that the red colored layer having a thickness of 1 μm was formed by washing with water, baking, and curing.

Similar to Example 1, the spectral reflection characteristics measured by applying incident light to the surface of the colored layer of the transparent electrode are shown by the solid line in FIG. Table 1 shows the reflectance at the specific wavelength and the three-dimensional coordinates (L, a, b). -Example 3- It is the same as Example 2 except that the red pigment at the time of electrodeposition was a green pigment and a green colored layer having a thickness of 1 m was formed.

FIG. 20 shows the spectral reflection characteristics, and Table 1 shows the reflectance at the specific wavelength and the three-dimensional coordinates (L, a, b). -Example 4- It is the same as Example 1 except that the red pigment at the time of electrodeposition was a blue pigment and a blue colored layer having a thickness of 1 m was formed.

FIG. 21 shows the spectral reflection characteristics, and Table 1 shows the reflectance and three-dimensional coordinates (L, a, b) at specific wavelengths. —Example 5— Thickness of 8 μm with ink containing red pigment before formation of transparent electrode
Forming a red colored layer of, and forming a transparent electrode on it,
Other than not forming a colored layer on the transparent electrode,
This is the same as the second embodiment.

FIG. 22 shows the spectral reflection characteristics, and Table 1 shows the reflectance and three-dimensional coordinates (L, a, b) at specific wavelengths. -Example 6- It is the same as Example 5 except that the red pigment at the time of printing was a green pigment and a green colored layer having a thickness of 10 μm was formed.

FIG. 23 shows the spectral reflection characteristics, and Table 1 shows the reflectance at the specific wavelength and the three-dimensional coordinates (L, a, b). —Example 7— The same as Example 5, except that the red pigment at the time of printing is a blue pigment and a blue colored layer having a thickness of 10 μm is formed.

FIG. 24 shows the spectral reflection characteristics, and Table 1 shows the reflectance at a specific wavelength and the three-dimensional coordinates (L, a, b). -Example 8- It is the same as Example 1 except having used the following as an insulating substrate instead of an alumina substrate.

Six pieces of epoxy resin-impregnated glass cloth prepreg were superposed, and a resin composition in which 230 parts by weight of titanium oxide (white inorganic powder: manufactured by Fuji Titanium Co., Ltd.) was added to 100 parts by weight of the epoxy resin was impregnated with a thickness of about 150 μm. The two glass cloth prepregs were laminated and cured at a predetermined temperature to produce an insulating substrate having a white surface. The spectral reflection characteristics are shown in FIG.
Is the same as. Table 1 shows the reflectance at the specific wavelength and the three-dimensional coordinates (L, a, b).

Example 9 The same as Example 2 except that the insulating substrate is the substrate used in Example 8. The spectral reflection characteristics, the reflectance at a specific wavelength, and the three-dimensional coordinates (L, a, b) were almost the same as in the case of Example 2. -Example 10- As an insulating substrate, a commercially available glass epoxy substrate was used as a base substrate, and a commercially available white paint [NAX-Mightylac (white) Nippon Paint Co., Ltd.] was applied thereon to a thickness of 20 μm to give a white surface. Other than that, it is the same as in Example 1.

The spectral reflection characteristics are the same as in FIG. Table 1 shows the reflectance and three-dimensional coordinates (L, a, b) at specific wavelengths.
Shown in. -Example 11-Example 2 except that the insulating substrate is the substrate used in Example 10
Is the same as. The spectral reflection characteristics, the reflectance at a specific wavelength, and the three-dimensional coordinates (L, a, b) were almost the same as in the case of Example 2.

-Comparative Example 1-The same as Example 1 except that the glass epoxy substrate used in Example 10 was used as an insulating substrate without being white-coated. The surface color of the glass epoxy substrate was pale blue-green. Spectral reflection characteristics are shown by a broken line in FIG. In addition, the reflectance at a specific wavelength and the three-dimensional coordinates (L, a,
b) is shown in Table 1.

Comparative Example 2 The same as Example 2 except that the glass epoxy substrate used in Example 10 was used as the insulating substrate without white coating. Spectral reflection characteristics are shown by broken lines in FIG. Also,
Table 1 shows the reflectance at the specific wavelength and the three-dimensional coordinates (L, a, b).

A liquid crystal element having the form of Structural Example B was manufactured in the same manner as in Examples 1 to 11, and Structural Example A was obtained.
The same result was obtained as in.

[0066]

[Table 1]

When the liquid crystal element of the example was driven, white, red, green and blue colors were clearly displayed on the screen.

[0068]

As described above in detail, in the liquid crystal element according to the present invention, the transparent electrodes for the pixels and the signal wiring paths and the connection terminals are formed separately on the front and back surfaces of the insulating substrate, not on the same surface. Therefore, it is not necessary to pass the signal wiring path and the power feeding wiring path between the adjacent transparent electrodes, and it is possible not only to greatly increase the density of pixels but also to make the transparent electrodes a white surface on the insulating substrate. The white-based surface does not lose its physical properties as a white-based even after the transparent electrode type or the colored layer forming coloring, and the display color is bright and appropriate, and the visibility is high.

When the colored layer is provided, there is also an advantage that a display with higher visibility can be performed by selecting a colorant that expresses an appropriate kind of color suitable for the display purpose. On the transparent electrode formation surface of the insulating substrate, there is a conductive land connected to the through hole and the transparent electrode is formed on the conductive land, or in the hole for the through hole, a taper that spreads toward the transparent electrode formation surface side. When the transparent electrode is formed so as to come into contact with the through-hole wiring path at the tapered portion, the liquid crystal element can be surely contacted with the transparent electrode and the through-hole wiring path. Has the advantage of improving reliability.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a basic configuration example of a liquid crystal element of the present invention.

FIG. 2 is a plan view showing a transparent electrode and a signal wiring path of the liquid crystal element of FIG.

FIG. 3 is a cross-sectional view showing another basic configuration example of the liquid crystal element of the present invention.

FIG. 4 is a plan view showing a transparent electrode formation surface of the liquid crystal element of FIG.

FIG. 5 is a plan view showing a connection terminal formation surface of the liquid crystal element of FIG.

FIG. 6 is a sectional view showing a step of forming a through hole in an insulating substrate.

FIG. 7 is a cross-sectional view showing a step of forming a recess for a land of an insulating substrate.

FIG. 8 is a cross-sectional view showing a step of forming a through hole in an insulating substrate.

FIG. 9 is a cross-sectional view showing the first half of a copper film patterning process for an insulating substrate.

FIG. 10 is a cross-sectional view showing the latter half of the copper film patterning process for the insulating substrate.

FIG. 11 is a cross-sectional view showing a step of forming a transparent electrode for a pixel.

FIG. 12 is a cross-sectional view showing another configuration example of the through-hole wiring board.

FIG. 13 is a cross-sectional view showing another configuration example of the through-hole wiring board.

FIG. 14 is a cross-sectional view showing a configuration example of a through-hole wiring board with a colored layer.

FIG. 15 is a cross-sectional view showing another configuration example of a through-hole wiring board with a colored layer.

FIG. 16 is a cross-sectional view showing a state of the liquid crystal element of the present invention when the liquid crystal layer is in an opaque state.

FIG. 17 is a cross-sectional view showing a state of the liquid crystal element of the present invention when the liquid crystal layer is in a transparent state.

FIG. 18 is a graph showing spectral reflection characteristics of transparent electrode surfaces of Examples and Comparative Examples.

FIG. 19 is a graph showing the spectral reflection characteristics of the colored layer surface of Examples and Comparative Examples.

FIG. 20 is a graph showing the spectral reflection characteristics of the colored layer surface of the example.

FIG. 21 is a graph showing the spectral reflection characteristics of the colored layer surface of the example.

FIG. 22 is a graph showing the spectral reflection characteristics of the electrode surface of the example.

FIG. 23 is a graph showing the spectral reflection characteristics of the electrode surface of the example.

FIG. 24 is a graph showing the spectral reflection characteristics of the electrode surface of the example.

FIG. 25 is a plan view showing a pixel electrode and a signal wiring path of a conventional liquid crystal element.

[Explanation of symbols]

 1 Transparent Substrate 2 Transparent Common Electrode 3 Polymer Composite Liquid Crystal Layer (Liquid Crystal Layer) 4 Transparent Electrode 5 Insulating Substrate 6 Signal Wiring Path 8 Through Hole Wiring Path 10 Connection Terminal 15 Coloring Layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Eiji Shiohama 1048 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works Co., Ltd.

Claims (4)

[Claims] 1. A transparent electrode is formed on one surface of an insulating substrate, and at least one of a signal wiring path and a connection terminal is formed on the opposite surface of the insulating substrate, and the transparent electrode and at least one of the signal wiring path and the connection terminal are the insulating substrate. A liquid crystal element which is connected to each other by a conductive path penetrating the transparent substrate, and a transparent electrode substrate is provided on the opposite side of the transparent electrode of the insulating substrate via a liquid crystal layer, At least a transparent electrode forming area of the liquid crystal element has a white surface. 2. The liquid crystal element according to claim 1, wherein a colored layer is formed on the front surface or the back surface of the transparent electrode formed on the insulating substrate. 3. A conductive path penetrating the insulating substrate is a through-hole wiring path, and a conductive land connected to the through-hole wiring path is formed on the transparent electrode formation surface of the insulating substrate, and the transparent electrode is The liquid crystal element according to claim 1, which is formed on the conductive land. 4. An electric path penetrating the insulating substrate is a through-hole wiring path, and the hole for the through-hole is tapered toward the transparent electrode formation surface side, and the transparent electrode is formed in the tapered portion. The liquid crystal element according to claim 1, wherein the liquid crystal element is formed so as to be in contact with the through hole wiring path.