JPS6362729B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an electrochromic display device in which upper and lower substrates that sandwich an electrolyte are bonded using an epoxy resin with an imidazole hardener to improve electrolyte resistance and the like. Electrochromic (hereinafter referred to as E and C)
The general structure of a display device will be explained based on the drawings. A transparent electrode 3 having a shape necessary for display is patterned on the upper transparent substrate 1, and a WO ₃ film 4, which is an electrochemical coloring substance, is further formed on the transparent electrode. 2 is a device substrate, which includes a background plate 5, a counter electrode 7, and an electrolyte 6, and an upper transparent substrate and an adhesive 1.
It is a container for packing with 9. 10 is an injection hole for injecting the electrolyte 6, and 11 is a sealant for final sealing the injection hole. Conventionally, the above structure has had the following limitations and problems. (1) Cannot be sealed at high temperatures (approximately 150℃ or higher). (2) Since the electrolyte is a solution of LiClO ₄ and propylene carbonate, it must be packaged with a stable sealant and adhesive. The reason for (1) is that at high temperatures, the oxidation state of the WO ₃ film becomes unstable, which adversely affects characteristics such as response speed and display density (contrast). In the case of (2), it must be sealed at low temperatures (approximately 150 degrees Celsius or less), so inorganic seals cannot be used, so organic seals are used. The problem in this case is that the propylene carbonate liquid corrodes most organic sealants, resulting in a short seal life and, as a result, a short life of the display device. The present invention aims to solve the above-mentioned problems and to produce an E/C display device with stable characteristics and a long life, and to provide a practical level E/C display device. The present invention will be explained below with reference to the structural diagram and the experimental data table in Table 1. First, the E and C display devices will be explained. The upper transparent substrate 1 is made of hard or semi-hard glass with a low Na content, and a low-resistance transparent electrode 3 is formed on the entire surface of the glass by vacuum evaporation, spraying, or the like. The substances are indium oxide (In ₂ O ₃ ) and tin oxide (SnO ₂ ).
It is a thin film with a thickness of 1000 to 5000 Å, and is used depending on the display specifications. The transparent electrode formed on the entire surface is patterned into an arbitrary shape using a photo technique, and unnecessary portions are etched using a chemil method or a dry method. A WO ₃ film 4, which is an electrically colored material, is laminated on the patterned transparent electrode 3. Since this WO ₃ film is electrically colored, it is formed into a shape that meets display specifications. The WO ₃ film is formed by a vacuum evaporation method, and a metal mask is set on the transparent electrode side to form a display shape, and a WO ₃ film of only the required shape is laminated on the transparent electrode. For example, when depositing the number 1, 50
~100μmm stainless metal is etched,
A WO ₃ film of 1 is formed by removing 1 and depositing it according to the above procedure. The film ranges from approximately 3000 to 6000 Å. The display method is to set the electrolyte (LiClO ₄
+ propylene carbonate solution) Li ⁺ ion in 6 is WO ₃
It uses an electrochemical reaction that enters the film and creates tungsten bronze, which becomes colored. XLi ⁺ ₊ ^WO3 ₊ ^{Xe - M +} is pulled out and becomes a colorless state. The applied voltage is about 1.0 to 2.0v. The counter electrode 7 is made of an inert material such as carbon or A _u , and 8 is a lead wire that serves to draw out the counter electrode 7. This is also an inert material and is generally made of A _u
Or a metal wire with a high reaction potential is used.
The coloring of the WO ₃ film is made more vivid by the background plate 5. A clear blue color is displayed on the generally white background plate. This background plate is made of a porous material to improve conductivity between the top and bottom, and the materials used include ceramics, paper, and a sheet of plastic filter mixed with TiO ₂ . The above substances and materials are packaged by the container substrate 2. 9 is the adhesive, 10 is an electrolyte injection hole, and 11 is a sealing material. This sealing material is a low melting point metal such as solder, and is made of a low melting point metal such as solder.
A metal film or the like is previously formed around the wafer, and solder is welded to the wafer. The device substrate 2 is made of the same glass material as the upper transparent substrate glass or a processed ceramic product. In the case of glass, _Cr - A _u is evaporated onto the injection hole. In the case of ceramic, the injection hole is metallized. In the structure of this display device, all materials other than adhesive 9 are made of inorganic materials and organic materials with strong solvent resistance, so they will not be attacked by the electrolyte propylene carbonate. Many adhesives have very weak propylene carbonate properties and cannot be put to practical use. In addition, there are also drawbacks such as high costs due to the large number of adhesives that are not suitable for mass production, so we conducted research and experiments focusing on propylene carbonate resistance, low temperature curing, and mass production. Then, we selected an adhesive that could meet these requirements to some extent, conducted preliminary tests, and were able to obtain the following adhesive. (1) Imidazole-based curing agent epoxy resin (2) Amine-based curing agent epoxy resin (3) Silicone rubber-based adhesive (4) Acrylic-based ultraviolet curing adhesive A reliability test was conducted on the test items. (1) Room temperature test (2) High temperature (60℃) test (3) High temperature and high humidity (45℃, 90%) test As a result, Table 1 was obtained.

【table】

[Table] ○: Practical
△: Needs improvement
×: Not practical. As a result, it was found that a practical level E and C display device is possible by using the imidazole curing agent epoxy resin. Table 1 will be explained. ○△× is an evaluation symbol, and the value in parentheses is the time when the E and C display devices were damaged.
Test items without parentheses indicate that they have not been damaged yet, and more than two years have passed. Since the high temperature, high temperature and humidity test is an accelerated test, the time in parentheses is one evaluation time, and generally it is about 1500 hours at high temperature (60℃), and about 1500 hours at high temperature (60℃),
90%), if you can clear about 750 hours, you will get about 5
It is said to have a lifespan of more than a year. In this experiment, we found that the water permeability of the adhesive has a very large effect in high-temperature and high-humidity tests. it is,
WO ₃ by water entering the E,C display
The problem is that the membrane dissolves. Silicone rubber adhesives are inferior in this respect.
At 1000 hours, the WO ₃ film had almost disappeared.
In the end, it was discovered that silicone rubber adhesives are highly water-absorbing or have high water permeability. To summarize the above results, etc., (1) Propylene carbonate resistance can be evaluated in room temperature and high temperature tests. (2) High temperature tests can evaluate adhesive strength. (3) The water permeability of adhesives can be evaluated in high temperature and high humidity tests. etc., and it became clear that clearing these tests would result in obtaining a practical level E or C display device. Based on the above results, the present invention uses an imidazole hardening agent epoxy resin for the upper transparent substrate 1 and the container substrate 2.
It was found that a highly reliable E, C display device could be obtained by using this as an adhesive. From this, (1) it can be constructed using an inexpensive organic sealant; (2) Since it is an organic sealant, it can be bonded at low temperatures. (3) Since it is an imidazole-based hardener epoxy resin, the sealant can be printed and it is easy to rationalize. With these wonderful effects, a practical and long-life electrochromic display device has been completed.

[Brief explanation of drawings]

The figure is a sectional view showing the structure of an electrochromic display device. DESCRIPTION OF SYMBOLS 1... Upper transparent substrate, 2... Device substrate, 3... Transparent electrode, 4... WO ₃ film, 5... Background plate, 6... Electrolyte, 7
... Counter electrode, 8... Counter electrode lead wire, 9... Adhesive, 10... Injection hole, 11... Sealing material.

Claims (1)

[Claims] 1 An electrolyte is sandwiched between a pair of substrates, at least one of which is transparent, and a plurality of display electrodes coated with an electrochemical coloring substance are formed on at least one of the substrates, and at least a part of the plurality of display electrodes is 1. An electrochromic display device comprising display pixels, wherein an electrolyte is sandwiched and a lower substrate is bonded with an epoxy resin having an imidazole hardening agent.