JPH0358092B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention is an electrochromic display (electrochemical color display, hereinafter abbreviated as ECD).
In particular, the present invention relates to an ECD capable of displaying a matrix pattern, which is manufactured by printing means, which is easy to manufacture, and whose display effect is improved.

ECDs can be broadly divided into those whose basic element, electrochemical coloring substance (hereinafter referred to as EC layer), is an inorganic substance and those whose basic element is an organic substance.
Those in which the EC layer is made of an inorganic material can be divided into those in which the proton (or cation) donor layer (hereinafter referred to as PS layer), which is another basic element, is solid and those in which it is liquid. If the EC layer is made of an organic substance such as biologen or the PS layer is a liquid, it is necessary to have a sealed structure to prevent liquid leakage and outside air from entering, which makes the structure of the display complex. In addition, the complicated manufacturing process resulted in high costs, and it was not possible to immediately apply it to other display materials such as LEDs and liquid crystals.

Such drawbacks are exacerbated as the number of pixels displayed increases, such as in matrix display.
The present inventors have proposed a technique that solved these problems in Japanese Patent Application No. 56-26358 and Japanese Patent Application No. 56-87760, etc.
It has already been shown that by making the PS layer a solid layer that can be formed by printing, we succeeded in simplifying the structure of the ECD and reducing its cost.

Furthermore, conventional ECD matrix displays, like matrix displays such as liquid crystals, have the effect of coloring the surrounding pixels when one matrix pixel develops color, causing the surrounding pixels to also develop some color, resulting in a decrease in visual quality and contrast. There were drawbacks that led to this. This development is also called crosstalk or cross-effect phenomenon, and has been a major problem for ECD drives. Furthermore, in order to create a matrix or multicolor ECD whose EC layer or PS layer is a liquid, it is necessary to divide each pixel into cells, making it extremely difficult to create a matrix, and a significant increase in manufacturing costs is unavoidable. Ta.

The present inventors have developed a matrix display type ECD that does not cause the above-mentioned cross-effect development by applying the novel printing technology disclosed in Japanese Patent Application No. 56-87760 and further improving the structure of the electrodes and insulating layers. The present invention was developed in an effort to provide an ECD that can easily display multiple colors and is easy to manufacture.

That is, the electrochromic display device of the present invention basically uses a transparent substrate such as glass or plastic as a support, and has at least an electrochemical coloring layer (EC layer) between the transparent electrode on the display side and the counter electrode.
and a solid proton donor layer (PS layer) interposed therebetween, in which at least one of the transparent electrode on the display side and the counter electrode is separated into electrodes in a matrix pattern. The solid proton donor layer is separated into a matrix pattern similar to a matrix electrode, and an insulating layer in a lattice pattern is provided to fill the gaps. This is a matrix display type electrochromic display body characterized in that the body layer and the insulating layer are formed by a printing method.

Below, we will discuss the ink for the solid proton donor layer and insulating layer formed by the printing method. First, the preferred main components of the solid PS layer are:
Titanic acid, stannic acid (SnO ₂ x H ₂ O), antimonic acid (Sb ₂ O ₃ x H ₂ O or Sb ₂ O ₅ x H ₂ O), zirconic acid (Zr(OH) ₄ x H ₂ O), Niobic acid (Nb ₂ O ₅ xH ₂ O), tantalic acid (Ta ₂ O ₃ xH ₂ O)
and silicic acid, or a mixture of two or more thereof. These materials are sometimes called hydrated metal oxides or metal oxide hydrates, but they are simply oxides such as titanium oxide, tin oxide, antimony oxide, zirconium oxide, tantalum oxide, and niobium oxide. Please note that this is completely different from mixing water with water from the outside.

Since these above-mentioned materials exhibit white color in a powder state, they are effective in increasing the whiteness of the base of a display device, and moreover, they themselves exhibit high proton conductivity. Its resistance value is 1×10 ⁴ to 1×10 ⁵ Ω/cm at room temperature.
The color development response of the electrochromic display device does not deteriorate when these are added, and on the contrary, both the response speed and the color development density are improved.

In addition, powders of titanic acid, stannic acid, zirconic acid, antimonic acid, niobic acid, tantalic acid, titanic acid, etc. mentioned above have the characteristics that they can be used with the addition of small amounts of binders used in printing inks and coating compositions. , their proton conductivity is preserved, and these layers, printed or coated and cured, are useful as solid PS layers in electrochromic displays.

As a binder, the vapor pressure at 20℃ is
Polyhydric alcohols, water-soluble polymers, or aqueous emulsion-type polymers that are normally liquid at 0.1 mmHg or less are preferred in order to maintain proton conductivity.
Further, as a solvent for forming an ink or coating composition, water or a water-soluble solvent such as lower alcohol, lower ketone, lower ether, etc. may be used.

Such a solid electrolyte has the advantage that it can be formed by printing, for example, screen printing or various coating methods, and can be applied to a wide range of thicknesses. For example, 2 to 2000μm can be used, especially 50 to 2000μm.
Preferred is a thickness of 400 μm.

On the other hand, it is basically preferable to use transparent insulating resin as the insulating layer. Here "transparent"
This means that unnecessary hues are not imparted to the display surface of the ECD, but as will be explained later, coloring agents are added to the insulating layer and PS layer.
It is also a layer that can give a convenient hue to ECD. A curable resin that does not contain a solvent, such as an oxidative polymerization type resin, an ultraviolet curable resin, a crosslinked polymerization type resin, etc., can be used as a basic component of the insulating layer.
An insulating layer can be obtained by printing these resins in a checkered pattern in an uncured state and then curing them. A cured epoxy resin layer is one example that can be used for the insulating layer.

Regarding the EC layer, it may be any organic or inorganic substance that has electrochromic properties, is solid or almost solid. For example, film-like EC containing biologen derivatives in glycerin or polyvinyl alcohol
Thin films such as tungsten oxide (WO ₃ ), molybdenum oxide (M ₀ O ₃ ), titanium oxide (TiO ₂ ), vanadium oxide (V ₂ O ₅ ), etc. are vacuum-deposited on display electrodes using an electron beam heating method. can give.

These EC layers do not necessarily have to be formed into a matrix pattern. However, if the colored state is to be maintained for a long time, in the case of a solid EC layer, the charge will diffuse and move to the surrounding EC layer that is not colored, causing the surrounding area to develop color, causing the display pattern to lose its sharpness. There is a fear. Practically speaking, it is preferable that the EC layer is also patterned in a matrix to match the shape of the PS layer. When a matrix-like EC layer is used, the clarity of the display pattern is maintained even in a long-term coloring state.

Next, regarding the counter electrode, a metal plate such as copper or aluminum is attached to the solid PS layer while maintaining electrical contact, or a conductive ink such as silver paste is applied on the solid PS layer. thing,
A thin metal film can be formed by vacuum evaporation, CVD, ion plating, etc. and used as a counter electrode, but by containing a reversible oxidizing substance in a part of the counter electrode, The time required for color development and fading can be reduced to 1/3 to 1/4. In particular, it is noteworthy that a counter electrode containing such a reversible oxidizing substance can also be formed by a printing method, and that an ink composition for this purpose can be provided.

Reversible oxidizing substances that are effective when added to the counter electrode include titanium dioxide, nickel oxide, cobalt oxide, iron oxide (FeO, Fe ₂ O ₃ or Fe ₃ O ₄ ), silicon dioxide, lead oxide, and copper oxide (CuO). , iron sulfide (FeS
In addition to metal oxides and sulfides such as FeS ₂ ), bismuth oxide (Bi ₂ O ₃ ), and niobium sulfide, hydroquinone derivatives and iron berlinate derivatives can be mentioned. In addition to the above-mentioned reversible oxidizing material, the reversible oxidizing material layer preferably contains carbon powder as a conductive filler for increasing electrical conductivity. Specifically, carbon blacks and carbon fibers such as buttress black, acetylene black, and conductive furnace black can be mentioned. These conductive fillers and powdered reversible oxidizing substances are combined with a suitable resin binder to form a reversible oxidizing substance layer, and the resin binders include acrylic resin, vinyl chloride resin, epoxy resin, melamine resin, and guanamine resin. Resin binders used in common printing inks can be used, such as , alkyd resins, methacrylic resins, etc.
By kneading these resin binder, conductive filler, and reversible oxidizing substance with a volatile solvent, an ink or coating composition for forming a reversible oxidizing substance layer is created. Considering that the volatile solvent mentioned here is applied by a printing method such as screen printing, the solvent is difficult to evaporate during printing, so the ink composition is less likely to change, and moreover, it can be applied quickly after printing. Preferably dry, with a boiling point of 150
It is a true solvent for resin binders at temperatures between ℃ and 270℃. Examples include diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, tripropylene glycol monomethyl ether, diethylene glycol monobutyl ether, 2-phenoxyethanol, N-methylpyrrolidone, and 2-pyrrolidone. These solvents are completely removed from the reversible oxidizer layer after coating and drying, except for a negligible trace amount remaining.

Furthermore, a trace amount of surfactant may be added to the above-mentioned ink for forming a reversible oxidizing substance to improve printability.

As a counter electrode, it is preferable to further provide a highly conductive layer in contact with this reversible oxidation material layer. A highly conductive layer is formed by using a commercially available silver paste or by kneading an ink with at least one metal conductive filler selected from silver, palladium, nickel, copper, etc., a resin binder, and a volatile solvent, and drying it. This improves the color development response.

This is because the reversible oxide layer alone has poor conductivity, but by adding this good conductivity layer to the back side, the conductivity increases, eliminating voltage drop, and as a result, it is thought that the color development and fading response improves. .

In addition, the transparent electrode on the display side is a conductive material made of tin oxide (SnO ₂ ), indium oxide (In ₂ O ₃ ), or a thin film of gold with a thickness of less than 400% formed by thin film formation technology such as vacuum evaporation or CVD. A membrane can be used.

According to the ECD of the present invention, color display can be easily achieved by adding a coloring material to one or both of the solid PS layer and the insulating layer. As mentioned earlier, the solid PS layer and insulating layer are formed by printing methods such as screen printing.
By adding colorants in the ink in a range of 0.01 to 10% by weight, any hue can be created.
Can be given to ECD. As a coloring agent,
It is preferable to use a colorant that can exist stably without dissolving or chemically changing in the solvent or binder used in the ink. It has been confirmed that such a coloring agent has no effect on electrical conductivity, and no adverse effects are observed even in the life of repeated coloring and fading. When the solid PS layer is colored, the EC layer becomes transparent when the EC layer is in a decolored state, and the colored background PS layer becomes visible on the display surface, causing the EC layer to become transparent.
When the layer is in a colored state, only the color of the EC layer is viewed, or a mixed color of the EC layer and the PS layer is developed on the display surface. The insulating layer has a lattice pattern, which means that an arbitrary color is given to the gaps between matrix pixels that change color and disappear.

Additionally, it is significant that the matrix-patterned PS layer and the lattice-patterned insulating layer are formed by printing means. Printing is essentially a means of mass-replicating patterned films, and its true strength lies in forming PS layers and insulating layers with complex shapes.

In the present invention, the selection of electrode patterns can be changed depending on the purpose. In the case of a fine matrix pattern in which each pixel of the matrix is about 1 mm square or less, the transparent electrode, which is the electrode on the display side, may be patterned by a known method using a photosensitive resist, and the counter electrode may be a single plane electrode. In the case of a relatively coarse matrix pattern where the pixel size is approximately 1 mm square or more, it is convenient to use a single transparent electrode as the transparent electrode on the display side, and form the counter electrode as each separate pixel in the matrix pattern. It is. The reason for this is that for fine patterns of 1 mm square or less, it is advantageous to use thin film patterning techniques such as mask evaporation, photo etching, and lift-off methods, and the transparent electrode on the display side is formed using a thin film suitable for such patterning techniques. This is because.

In the ECD of the present invention, at least one electrode is formed into a matrix, and a solid PS layer is formed into a matrix according to the shape of this electrode, and furthermore,
By matrixing each separated
Since the insulating layer is provided in a grid pattern in the gap between the PS layers, when a display voltage is applied between the transparent electrode on the display side and the counter electrode, the EC
Charge carriers such as protons (H ⁺ ) or cations that are involved in coloring and fading of layers conduct only within solid PS layers that are individually isolated and insulated, and charge carriers are adjacent to one PS layer. There is no possibility of diffusion and conduction to the surrounding PS layer that is also present. In other words, the charge carriers involved in color development and decolorization are supplied only to the portion of the EC layer that is in electrical contact with the matrix-like solid PS layer. Coloration does not occur, causing ripples of color development and fading in the surrounding EC layer.
That is, an ECD with a matrix display in which no cross-effect phenomenon occurs is provided.

Moreover, the ECD of the present invention is an ECD that can form a large number of color-developing and fading pixels on a single support,
Its structure is solid as it is entirely solid. In addition, since the solid PS layer and insulating layer are formed by printing methods such as screen printing,
Patterning such as a matrix or a grid pattern can be easily performed, which provides great convenience in manufacturing the ECD of the present invention, and makes the ECD low in manufacturing cost. Since it has a structure in which a large number of matrix pixels can be incorporated into a small display, the patterns that can be displayed are also rich in variety, making it a matrix display type electrochromic display that has entered the practical range.

Embodiments of the present invention will be described below based on FIGS. 1 and 2 of the drawings, but it goes without saying that the present invention is not limited to these embodiments.

Embodiment FIG. 1 is a schematic sectional view showing an example of an electrochromic display of the present invention, and FIG. 2 is a plan view thereof.

A transparent conductive film of indium oxide containing 5% tin oxide is formed on one side of a transparent substrate 8 made of glass as a transparent electrode 1 on the display side, and tungsten oxide (WO ₃ ) is formed on it in a matrix pattern.
EC layers 2, 9, 10, and 11 were formed by vapor deposition into 4 mm squares with an interval of 2 mm between them. Furthermore, the insulating layers 3 and 12 are coated with epoxy resin screen ink (#25-000 manufactured by Toyo Ink Mfg. Co., Ltd.) to prevent the display electrode 1 from exposing parts other than the EC layers 2, 9, 10, and 11. A 2 mm grid pattern was printed. Next, metastannic acid (manufactured by Mitsuwa Chemicals)
is mixed with glycerin at a ratio of 4:1 to form an ink.
A 4 mm square matrix pattern with a thickness of approximately 200 μm was formed by screen printing to match the EC layer, and the PS
It was set as layer 4. PS layer 4 is colored by adding 2 to 0.5% of DuPont's chromaline toner (organic pigment) to the total amount of metastannic acid ink to create yellow ink (yellow), magenta ink (red), and cyan ink (indigo).
was produced and printed three times in total with each ink, resulting in 9 yellow pixels, 10 magenta pixels, and 11 cyan pixels. On this PS layer 4, a conductive paint Dotite D-550 (manufactured by Fujikura Kasei Co., Ltd.) was screen printed and laminated as a counter electrode 6. Furthermore, an insulating protective layer 5 is screen printed on the counter electrode 6 using the same epoxy resin as the insulating layer 3, except for the terminal part 7 for drawing out the electrode, thereby forming a multicolor matrix ECD having 9×9 pixels. Created. When the display electrode 1 of this ECD was used as a negative electrode and all of the counter electrodes 6 were used as positive electrodes, all pixels (all EC layers) were colored blue by applying a voltage of 1.3V, the ECD screen became black.
By reversing the direction of the applied voltage and decolorizing only the EC layer 9 of the yellow pixel to make it transparent, the background of the yellow pixel can be erased.
The yellow of PS layer 4 was visible and it appeared yellow as an ECD screen, and if only the magenta pixel EC layer 10 was decolored, it appeared red. The cyan pixels also appeared indigo using the same operation, making it an interesting matrix-type ECD capable of color display. By specifying and coloring a pixel, it is possible to display a variety of characters, graphs, videos, etc. in multiple colors, and when one pixel is colored, surrounding pixels do not color in a ripple manner, and cross-color display is possible. It was an ECD with a matrix display in which no effect phenomenon was observed.

In the above embodiment, as a method for coloring pixels,
Although we have shown a method of mixing pigments into the PS layer, dyes may also be used as long as they do not have a large effect on the color development of the EC layer or the mobility of protons. Further, coloring is not limited to the PS layer, but may also be applied to an insulating layer, a method of providing a color filter on the outside of a transparent substrate, a method of coloring a transparent substrate, and the present invention is not limited to these methods.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of the electrochromic display of the present invention, and FIG. 2 is a plan view showing the electrochromic display of FIG. 1 as viewed from the display surface. . 1...Transparent electrode, 2,9,10,11...EC
Layer, 3, 12... Insulating layer, 4... PS layer, 6...
Counter electrode, 8...transparent substrate.

Claims (1)

[Scope of Claims] 1. In an electrochromic display comprising at least an electrochemical coloring layer and a solid proton donor layer interposed between a transparent electrode on the display side and a counter electrode, the transparent electrode on the display side At least one of the electrode and the counter electrode is separated in a matrix pattern, and the solid proton donor layer is similarly separated in the matrix pattern according to the electrode, and a lattice pattern is formed in the gap between the solid proton donor layers. 1. A matrix display type electrochromic display comprising an insulating layer, wherein the solid proton donor layer and the insulating layer are formed by a printing method. 2. The solid proton donor layer contains titanic acid, stannic acid, antimonic acid, zirconic acid, niobic acid,
The main component is one or a mixture of two or more selected from tantalic acid and silicic acid, and is bound with at least one binder selected from polyhydric alcohols, water-soluble polymers, and aqueous emulsion type polymers. The first claim is
The electrochromic display described in Section 1. 3. The electrochromic display according to claim 1, wherein the electrochemical coloring layers are separated into matrix patterns according to the proton donor layers. 4. The electrochromic display according to claim 1, wherein the insulating layer is formed by printing and curing an insulating resin in an uncured state. 5. The electrochromic display according to claim 1, wherein at least one of the insulating layer and the solid proton donor layer contains 0.01 to 10 percent by weight of a coloring material. 6. The electrochromic display according to claim 1, wherein the counter electrode contains a reversible oxidizing substance.