JPH0145894B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thin film type electrochromic display (electrochemical color display).
The present invention relates to improvements in ECD (hereinafter abbreviated as ECD), and in particular to thin film displays with improved appearance and service life by arranging insulating layers in optimal positions and selecting materials for them.

ECDs can be roughly divided into those whose basic element, the electrochemical coloring layer (hereinafter abbreviated as EC layer), is made of inorganic material and those whose electrochemical coloring layer is made of organic material.
Those whose layers are made of inorganic substances can be divided into those whose proton (or cation) donor layer (hereinafter referred to as PS layer), which is another basic element, is solid and those whose layer is liquid. If the EC layer is made of an organic substance such as biologen, or if the PS layer is a liquid, the structure of the display element will be complicated due to the need to prevent liquid leakage and have a sealed structure.
Due to the complexity of the manufacturing process, the manufacturing cost of display elements became extremely high, and other display elements such as LEDs and liquid crystals could not be used immediately. EC layer and
A structure in which both PS layers are solid can be manufactured by a single process called vapor deposition or by a process called printing, which has a significant cost advantage.

Recently, research on all-solid-state ECDs has progressed, and they are approaching the point of practical application, but one major problem is that as the display electrodes are formed with indium oxide, etc. One drawback is that the transparent electrode on the front glass substrate is gradually reduced and turns brownish. To avoid this, silicon dioxide (SiO ₂ ), magnesium fluoride (MgF ₂ ), cerium oxide (Ce ₂ O ₃ ), and silicon nitride (Si ₃ N ₄ ) are applied to the entire surface of the display electrode except for the display pattern area. etc., but it did not fundamentally solve the problem. This means that SiO ₂ , MgF ₂ , Ce ₂ O ₃ , Si ₃ N ₄ etc.
Because it is a thin film of about 1.5 Å thick and has some proton mobility, when a voltage is applied, protons that have passed through the EC layer from the proton supply layer, which is the supply source, also pass through these insulating layers and reach the display electrode. This was to reduce the amount of When indium oxide, which is a constituent material of display electrodes, is reduced, it not only changes color as mentioned above, but also decreases electrical conductivity, which reduces both color density and color development speed, reducing its value as an ECD. .

The present invention has been made to solve the above-mentioned problems, and is directed to an electrochromic display having at least a display electrode, an electrochemical coloring layer, a proton donor layer, and a counter electrode. A thin film display, characterized in that an insulating layer having a shape excluding a portion is provided between the proton donor layer and the counter electrode, and the material constituting the insulating layer is an alkali metal oxide,
An insulating film-forming material containing an alkaline earth metal oxide alone or containing these oxides is used.
Insulating layers containing these alkali metal oxides and alkaline earth metal oxides were experimentally extremely effective in solving the above problems. Alkali metal elements include lithium, sodium, potassium, rubidium, cesium, and francium; alkaline earth metal elements include beryllium, magnesium, calcium,
There are strontium, barium, and radium, and in the present invention, oxides of elements other than extremely expensive francium and radium are used alone, or these oxides are combined with other film-forming materials such as silicon dioxide and titanium oxide. used. Most of the oxides of alkali metal elements and some of the oxides of alkaline earth metal elements change by absorbing moisture and carbon dioxide gas in the air when they are alone, and when they are alone, they are not stable as a deposited film. It is difficult to exist in Therefore, other deposition materials SiO ₂
and TiO ₂ to ensure stability as an insulating film.

FIG. 1 is an enlarged sectional view of essential parts showing an example of the thin film display of the present invention, and this will be explained as follows.
A transparent conductive film made of tin oxide (SnO ₂ ) or indium oxide (In ₂ O ₃ ) alone or in combination is laminated as a display electrode 2 on one side of a transparent substrate 1 made of glass, synthetic resin, etc. The EC layer 3 is formed by vapor-depositing an electrochromic material such as tungsten oxide (WO ₃ ) in the shape of a desired graphic or lexical pattern. Next, a solid type PS layer 4 that supplies protons (or cations) to the EC layer 3 by applying a voltage and causes reduction color development.
, and before forming the counter electrode 6, corresponds to the area other than the displayed pattern area, that is, the area where the EC layer 3 is not applied in this example.
An insulating layer 5 is formed on the surface of the PS layer 4. Note that the layer 7 formed on the counter electrode 6 is a light antireflection layer, and is provided to enhance the contrast of the display section.

Hereinafter, the present invention will be explained in detail together with examples.

<Example 1> A transparent display electrode 2 made of indium oxide with 5% tin oxide added was formed on a glass transparent substrate 1, and tungsten oxide was patterned to a thickness of 5000 Å on this display electrode 2. Electrochemical coloring layer 3
Then, a chromium oxide layer and a silicon dioxide layer containing 20% boron oxide are laminated as a proton donor layer 4 with a total thickness of 3000 Å, and then a pattern other than the previously formed tungsten oxide electrochemical coloring layer 3 is formed. Barium oxide was deposited (as a negative pattern) on the entire surface as an insulating layer 5 with a thickness of 800 Å, gold as a counter electrode 6 with a thickness of 150 Å, and silicon dioxide as a light antireflection layer 7 with a thickness of 800 Å. The lamination method is all vacuum evaporation, and in forming the insulating layer 5, pressure-molded barium oxide tablets containing 30 to 50% titanium oxide are used as the evaporation source. there was. Regarding the barium oxide vapor deposition film, it becomes a barium oxide enriched layer of about 60 to 90%,
With the counter electrode 6 as the positive electrode, no protons are generated when a voltage of 1 to 3 V is applied, and no reduction of the display electrode 2 is observed even after 10 ⁷ or more repetitions, indicating that barium oxide has extremely good insulation against protons. confirmed. The insulation layer 5 is removed by applying 1 to 2V.
The portion of the electrochemical coloring layer 3 that has not been colored develops blue.

<Example 2> In Example 2, as in Example 1, a 5000 Å film was placed on a glass transparent substrate 1 on which a transparent display electrode 2 was formed.
Electrochemical coloring layer 3 was formed by patterning tungsten oxide to a thickness of 1,800 Å, and proton donor layer 4 was formed by laminating a chromium oxide layer to a thickness of 1800 Å. Next, a tablet made by press-molding a mixture of 20% sodium oxide, 15% calcium oxide, and 65% silicon dioxide was used as an evaporation material to insulate the parts other than the pattern of the electrochemical coloring layer 3 to a thickness of 800 Å by vacuum evaporation. It was arranged as layer 5. Furthermore, 150% gold was added as the counter electrode 6.
Å, magnesium fluoride is used as the anti-reflection layer 7.
The film was laminated to a thickness of 700 Å over the entire surface to form a thin film display.

When a voltage of 1.3V was applied between the display electrode 2 and the counter electrode 6 of this thin film display with the latter being used as the positive electrode, the electrochemical coloring layer 3 developed a blue color, and the portion where the insulating layer 5 was applied did not change color. No reduction of the display electrode 2 was observed even after repeating coloring and fading more than ¹⁰ times, confirming that the insulating layer 5 was extremely effective in blocking protons.

In the above embodiments of the present invention, the method of forming the insulating layer is exemplified by the vapor deposition method, but the present invention is not limited to this, and may be performed using known techniques such as sputtering, CVD, ion plating, etc. Alternatively, a film forming method such as printing, coating, bonding, etc. may be used in which a resin contains an alkali oxide or an alkaline earth oxide.

Furthermore, there is no limitation on the mixing ratio or method of the alkali metal oxide or alkaline earth metal oxide contained in the insulating layer.

The present invention prevents the reduction of the display electrode, which has been a problem in electrochromic displays, and
In addition, due to its anti-reduction effect, the proton donor layer can be coated over the entire surface of the display, making it difficult to distinguish the patterned area from other non-patterned areas when decolored, increasing the contrast with the coloring This greatly increases the product value of the product.

[Brief explanation of drawings]

FIG. 1 is an enlarged sectional view of essential parts showing an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...Transparent substrate, 2...Display electrode, 3...Electrochemical coloring layer (EC layer), 4...Proton donor layer (PS
layer), 5...insulating layer, 6... counter electrode.

Claims (1)

[Claims] 1. A solid-state electrochromic display comprising at least a display electrode, an electrochemical coloring layer, a proton donor layer, and a counter electrode in this order, excluding a pattern portion to be displayed. A thin film display, characterized in that a shaped insulating layer is provided between the proton donor layer and the counter electrode. 2. The thin film display according to claim 1, wherein the material constituting the insulating layer is an insulating film-forming material containing an alkali metal oxide, an alkaline earth metal oxide alone, or an oxide of these oxides.