JPS6336485B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an electrochromic display device that produces a reversible color change by applying an electric field to an electrochromic material, and more particularly to its electrodes. FIG. 1 is a cross-sectional view of the prior art. A transparent electrode 2 is formed on a transparent glass substrate 1. On this transparent electrode 2, tungsten oxide (WO ₃ ) 3 as an electrochromic material is provided.
Further, an insulating film 4 is formed on the remaining part of the transparent electrode 2. Another glass substrate 5 facing this glass substrate 1 is formed into a cap shape. A conductor 6 is deposited or sputtered on the inner wall of the glass substrate 5 . On this conductor 6, the other electrode 7 is deposited or sputtered. A white porous plate 8 is interposed between the electrode 7 and the electrochromic material 3. The substrates 1 and 5 are hermetically fixed with an adhesive 9. The space within the substrates 1 and 5 is filled with an electrolytic solution 10. This space accommodates air bubbles 11 to absorb thermal expansion of the electrolytic solution 10. Since the electrode 7 is made of tungsten oxide, the following redox reaction is carried out. WO ₃ +xM ⁺ +xe ^- MxWO ₃ where x is a natural number and M represents a metal atom. In the electrode 7 made of tungsten oxide, the reversible potential generated by the oxidized ring element of the tungsten oxide changes significantly depending on its charge retention ability, that is, the degree of reduction of tungsten in MxWO ₃ (the value of the valence x of the metal). Therefore, when driving by applying a constant voltage between the electrode 2 and the conductor 6, the electrode 2
The potential of will change. Therefore, the degree of color development of the electrochromic substance 3 varies, and a phenomenon called so-called uneven color development occurs. Further, the amount of charge held by the tungsten oxide electrode 7 changes over time, and the potential of the tungsten oxide changes over time. This change over time is particularly significant at high temperatures. In addition, the oxidation degree of tungsten oxide is hexavalent,
A higher degree of oxidation cannot be achieved. Therefore, when first causing a color reaction in an electrochromic device, the tungsten oxide electrode 7
The reaction in the oxidation direction is difficult to occur quickly. In order to smoothly carry out this initial coloring reaction, it is necessary to apply a relatively high voltage between the electrode 2 and the conductor 6.
There is a problem in that this causes deterioration of zero and shortens the life of the electrochromic device. It is known that manganese oxide is suitable as an electrode material instead of tungsten oxide because its potential is stable. Conventionally, the electrode 7 is formed by applying manganese oxide powder, carbon powder, and a binder in the form of a paste or fluid onto the conductor 6. As the binder, organic polymer substances such as epoxy resin, silicone resin, and phenolic resin are used. In such prior art,
The electrode 7 has a large concentration polarization and a large specific resistance. Therefore, the response speed for color development and decolorization was slow, and the potential of manganese oxide was unstable. This is because the manganese oxide powder and the carbon powder are covered with the binder, which reduces the activity of the manganese oxide and increases the resistance at the interface between the carbon powder. Other prior art solutions to this problem use tar, pitch or molasses as the binder. A mixture of manganese oxide powder, carbon powder, and binder is fired at over 1,000 degrees to form a plate, which is used as an electrode. At such a high firing temperature, manganese oxide decomposes and phase transition occurs, making it impossible to fully exhibit the advantageous property of manganese oxide having a stable potential. Therefore, the main object of the present invention is to provide an electrochromic display device having an excellent electrode with stable potential. The present invention provides a first electrode 16 formed on the first substrate 15 and a first electrode 16 on the first electrode 16 in an airtight space formed by the first substrate 15 and the second substrate 21 fixed thereto. an electrochromic material 17 provided on the substrate; a perforated plate 19 forming a background of the electrochromic material 17; and a mixture formed on the perforated plate 19 and consisting of an active material powder and a conductive powder, which is formed by pressure molding. A second electrode 20 configured, and a conductive elastic body 24 disposed on the second electrode 20.
This is an electrochromic display device characterized in that: and a conductor 23 provided on a conductive elastic body 24 are arranged in this order, and the space is filled with an electrolytic solution 25. In a preferred embodiment, the active material is manganese oxide, Praxian blue, FeO, Fe ₃ O ₄ , Nb ₃ O ₄ ,
Nb ₂ O ₅ , TiO ₂ , Ti ₂ O ₃ , MoO ₃ , MoS ₃ , Li ₂ Wo ₄ ,
_SnO2 , PbO, _Ir2O3 , _IrO2 , _Cu2O , _CuO ,
It is characterized by containing one or a mixture of two or more selected from Bi ₂ O ₃ , Bi ₂ O ₅ , V ₂ O ₃ , V ₂ O ₅ , copper phthalocyanine, cobalt complex, iron complex, SnSe, and TiS ₂ . In a preferred embodiment, the conductor powder is expanded graphite. FIG. 2 is a bottom view of an embodiment of the present invention, and FIGS. 3 and 4 are cross-section lines - and - of FIG. 2.
FIG. A transparent electrode 16 is deposited on the transparent glass substrate 15 .
This electrode 16 is made of a material such as indium oxide or tin oxide. The electrochromic material 17 is, for example, tungsten oxide (WO ₃ ).
It is a thin film and is deposited on the electrode 16. This electrochromic material 17 corresponds to each segment of the character to be displayed. An insulating film 18 is formed on the remaining part of the electrode 16. This insulating film 18 is made of a material such as silicon oxide or aluminum oxide. A perforated plate 19 is provided over the electrochromic material 17. Perforated plate 1
Reference numeral 9 is white to form a background when the electrochromic material 17 is colored, and is made of an electrically insulating material such as ceramic or fluorine resin.
Another electrode 20 is arranged on the perforated plate 19 on the side opposite the electrochromic material 17. A cap-shaped glass substrate 21 having a flange 33 is fixed onto the glass substrate 15 with an adhesive 22, and an airtight internal space is formed between the glass substrates 15 and 21. A power supply conductor 23 is provided on the inner surface of the glass substrate 21 along the longitudinal direction (left-right direction in FIG. 2) up to the flange 33.
is deposited. A conductive elastic body 24, such as carbon fiber, is interposed between the conductor 23 and the electrode 20. The conductive elastic body 24 has an elastic force in its thickness direction (vertical direction in FIGS. 3 and 4). For example, this carbon fiber is manufactured by Toray Industries, Inc. under the trade name Torayka Matsu.
B0030 is preferred. The internal space contains an electrolytic solution 2
5 is filled. This electrolytic solution 25 is 1 mol/
γ-butyrolactone solution containing Lic10 ₄ . Air bubbles 26 are accommodated in a portion of this internal space. The bubbles 26 are for absorbing thermal expansion of the electrolytic solution 25 to prevent damage to the glass substrates 15, 21, etc. The conductor 23 may be comprised of metals, metal oxides such as indium oxide and tin oxide, graphite, and carbon such as carbon black. The electrode 20 is made of 300 mesh manganese dioxide powder and expanded graphite (trade name: EXP- manufactured by Nippon Graphite Co., Ltd.).
F200) were mixed at a weight ratio of 50:50 and pressure-molded into a plate shape under a pressure of 5 tons/cm ² . The specific resistance of this electrode 20 is less than 0.1 Ωcm, and the polarization resistance in the electrolyte 25 is less than 10 Ω/cm ² .
According to the inventor's experiments, such an electrode 20
The reversible potential of the electrode 20 was stable during color development and decolorization (that is, during redox reaction of the electrode 20) and even when left at a high temperature of 70°C. A flange 33 is provided on the glass substrate 15.
A connection terminal 27 for electrically connecting to the conductor 23 is formed. The connection terminal 27 and the conductor 23 are electrically connected via a metal foil 28. A conductive adhesive may be used instead of this metal foil 28. Expanded graphite is produced by immersing graphite in sulfuric acid, drying it, and then heating it. The conductive elastic body 24 achieves electrical connection between the electrode 20 and the conductor 23, and also functions to fix the porous plate 19 and the electrode 20 by its elastic force in the thickness direction. This electrode 20 and conductor 23
comes into elastic contact with the conductive elastic body 24, and is in substantially surface contact with the conductive elastic body 24. This has the advantage that the contact resistance between the electrode 20 and the conductor 23 with respect to the conductive elastic body 24 is reduced. Furthermore, even if the electrode 20 is deformed or broken, the electrical connection between the electrode 20 and the conductor 23 is reliably established. Therefore, there is no need to unnecessarily increase the strength of the electrode 20, and therefore the electrode 20 can be manufactured easily. Note that the bubbles do not enter into the conductive elastic body 24 due to their surface tension, so that the electrochromic display phenomenon can be performed reliably. According to the embodiment described above, when manufacturing an electrochromic display device, the glass substrate 1 on which the electrochromic material 17 etc. are formed is used.
5 and the glass substrate 21 on which the conductor 23 is formed, the porous plate 19, the electrode 20, and the conductive elastic body 24 are interposed, and the conductor 23 and the connection terminal 27
This is completed by interposing a metal foil 28 between them. Therefore, the manufacturing process is extremely simple.
Conventionally, the conductive elastic body 24 and the conductor 23 are not provided, and a lead wire connected to an electrode made of another material in place of the electrode 20 is guided outside through a hole drilled in the glass substrate 21, and then this hole is opened. It is sealed airtight. Manufacturing an electrochromic display device having such a conventional structure is extremely complicated. In contrast, the above-described embodiments are superior in mass production and can be produced at low prices. Furthermore, in conventional electrochromic display devices, the lead wires connected to the conventional electrodes corresponding to the electrodes 20 are led out through holes drilled in the glass substrate 21, so that other electrodes 16 are included. Therefore, the electrical connection work with the drive circuit is troublesome. In the embodiment described above, the electrode 20 is electrically connected to the connection terminal 27 formed on the same plane as the other electrodes 16, so that the electrical connection with the drive circuit can be made using a conventional connector. You will be able to do it easily. According to experiments by the present inventor, when a constant voltage was applied between the electrode 16 and the connection terminal 27 in the above-mentioned embodiment, the uneven coloring that occurred in the prior art did not occur in the present embodiment. In addition, when the first color develops, the electrode 16 and the connecting terminal 27
Unlike the prior art described above, there is no need to apply a high voltage to the electrochromic display device, and therefore the life of the electrochromic display device of this embodiment can be extended. In addition, the manganese oxide powder, carbon powder, and epoxy resin mentioned above as the prior art,
In an electrode made of a molded body made of a binder made of an organic polymer substance such as a silicone resin and a phenol resin, when the molded body is used as the electrode 20, it takes about 1 second to develop a response after applying a voltage. Although there was a delay, in the example described above, the response delay could be reduced to about 100 milliseconds due to the small concentration polarization of the electrodes 20.

[Table] Table 1 shows experimental data regarding the electrode 20 by the present inventor. This electrode 20 is made of 300 mesh manganese dioxide powder and expanded graphite (trade name: EXP-F200 manufactured by Nippon Graphite Co., Ltd.), and when the weight composition ratio is changed, the molding pressure when pressurized at room temperature is Those in which an electrode with the same shape as the mold was obtained when the electrode was changed are marked with an ○, and those in which the shape of the mold could not be obtained and molding was impossible are marked with an x. All of these electrode samples marked with a circle could be satisfactorily used as the electrode 20. Since these moldings were carried out at room temperature, decomposition of the active material manganese dioxide and crystal phase transition did not occur, and an electrode capable of maintaining a stable potential could be realized. The above-mentioned active materials include manganese oxide, Praxian blue, FeO, Fe ₃ O ₄ , Nb ₃ O ₄ , Nb ₂ O ₅ , TiO ₂ ,
_Ti2O3 , _MoO3 , _MoS3 , _Li2Wo4 , _{SnO2 , PbO} ,
_{Ir2O3 , IrO2} , _{Cu2O ,} CuO, _Bi2O3 , _{Bi2O5 ,}
It may be a pressure-molded mixture of one or more selected from the group consisting of V ₂ O ₃ , V ₂ O ₅ , copper phthalocyanine, cobalt complex, iron complex, SnSe, and TiS ₂ . Manganese oxide includes not only manganese dioxide but also manganese monoxide.
MnO, manganese trioxide Mn ₂ O ₃ , manganese tetroxide
It may be Mn ₃ O ₄ or a mixture thereof. Instead of graphite, other conductive powders may be used. The invention also provides that in solutions such as potassium bromide,
An electrochromic display device containing an electrochromic substance such as pebyl pyrogen bromide or Lu-diphthalocyanine, which undergoes an oxidation-reduction reaction to produce a colored, insoluble reactant on the cathode. It is specifically pointed out that it can be carried out in connection with its cathode or anode. In manufacturing the electrochromic display device described above, the electrochromic material 17
A glass substrate 15 on which a conductor 23 and the like are integrally formed, and a glass substrate 21 on which a conductor 23 is integrally formed are prepared, and then these glass substrates 15, 21 are prepared.
are placed facing each other with a porous plate 19 and an electrode 20 interposed therebetween, and filled with an electrolytic solution 25, and then an adhesive 2
Both glass substrates 15 and 21 are held in pressure contact with each other in the direction of proximity until the glass substrates 2 are cured. As the adhesive 22, for example, SE1700 white manufactured by Toray Silicon Co., Ltd. may be used, and when this adhesive is used,
Cures in about 10 minutes in an atmosphere of 150℃. During the time until the adhesive 22 hardens, the glass substrates 15 and 21 are kept pressed in the direction of mutual proximity, so that the electrode 20 and the conductor 23 are substantially in surface contact, This state of surface contact will be maintained even after the adhesive 22 is cured. As described above, according to the present invention, since the electrode is formed by pressure molding a mixture of active material powder and conductor powder, the concentration polarization of the electrode is greater than in the case of using a binder as in the past. can be made small, and specific resistance can be made small. Therefore, the response speed can be improved, and the potential of the electrode is prevented from becoming unstable, so that uneven coloring does not occur. Moreover, since this pressure molding can be carried out, for example, at room temperature, decomposition and phase transition of the active material are prevented. In particular, in the present invention, a conductive elastic body 24 is interposed between the second electrode 20 and the conductor 23. As a result, the contact resistance between the second electrode 20 and the conductor 23 with respect to the conductive elastic body can be reduced, and even if the second electrode 20 is deformed or broken, the contact resistance between the second electrode 20 and the conductor 23 can be reduced. The electrical connection is made securely. Therefore, there is no need to increase the strength of the second electrode 20 unnecessarily, and therefore the manufacture of the second electrode 20 becomes easier.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the prior art, FIG. 2 is a bottom view of an embodiment of the present invention, and FIGS. 3 and 4 are sectional views taken from the cutting plane lines - and - in FIG. 2, respectively. . 15, 21... Glass substrate, 16, 20... Electrode, 17... Electrochromic substance, 18...
...Insulating film, 19... Porous plate, 22... Adhesive, 2
3...Electrical conductor for power supply, 24...Electroconductive elastic body, 2
5... Electrolyte, 26... Bubbles, 27... Connection terminal, 28... Metal foil.

Claims (1)

[Claims] 1. A first electrode 16 formed on the first substrate 15, and a first electrode 16 formed on the first substrate 15 in an airtight space formed by the first substrate 15 and the second substrate 21 fixed thereto. An electrochromic material 17 provided on the electrode 16; a perforated plate 19 forming a background of the electrochromic material 17; and a mixture formed on the perforated plate 19 and consisting of an active material powder and a conductive powder. A second electrode 20 formed by molding, and a conductive elastic body 24 disposed on the second electrode 20.
An electrochromic display device characterized in that: and a conductor 23 provided on a conductive elastic body 24 are arranged in this order, and the space is filled with an electrolytic solution 25. 2 The active materials are manganese oxide, Prasyan Blue, FeO, Fe ₃ O ₄ , Nb ₃ O ₄ , Nb ₂ O ₅ , TiO ₂ ,
_Ti2O3 , _MoO3 , _MoS3 , _Li2Wo4 , _{SnO2 , PbO} ,
_{Ir2O3 , IrO2} , _{Cu2O ,} CuO, _Bi2O3 , _{Bi2O5 ,}
The electrolyte according to claim 1, characterized in that it contains one or a mixture of two or more selected from V ₂ O ₃ , V ₂ O ₅ , copper phthalocyanine, cobalt complex, iron complex, SnSe, and TiS ₂ . Chromic display device. 3. The electrochromic display device according to claim 1 or 2, wherein the conductor powder is expanded graphite.