JPH06100758B2 - Electrochromic display - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrochromic display device (hereinafter referred to as ECD) capable of displaying a plurality of different information in a plurality of different colors.

Background Art and Its Problems ECD is a display device that utilizes a phenomenon (electrochromism) that causes a reversible color change when an electric field is applied. It is a solution electrolyte type in which the electrolyte is a solution, or a solid electrolyte in which the electrolyte is a solid. Various ECDs such as molds are known.

A solution electrolyte type ECD in which a substance that causes coloring or color change by applying an electric field (hereinafter referred to as an EC substance) and an electrolytic solution are enclosed in an ECD cell and an electric field is applied to the electrolytic solution for display is , A dissolution type in which the EC substance is dissolved in the electrolytic solution before and after the electric field is applied, a precipitation type in which the EC substance dissolved in the electrolytic solution is deposited on the electrode after the electric field is applied, and the EC substance is It is roughly divided into the fixed type fixed on the top. However, these ECDs using an electrolytic solution are monochromatic ECDs, and one type of EC substance is colored or changes in color when an electric field is applied to display.

Clearly, it would be more convenient than the conventional monochromatic ECD if a multicolor ECD capable of displaying various information in different colors was obtained, and development thereof was strongly desired.

As an ECD capable of displaying multiple colors, an EC substance that develops color upon reduction (hereinafter referred to as reduced EC substance) and a substance that develops color upon oxidation (hereinafter referred to as oxidized EC substance) are dispersed in a synthetic polymer. JP-A-58-80625 discloses an all-solid-state ECD in which a colored active material layer is provided on a display electrode. This all-solid-state ECD is in a color erasing state when the applied voltage is 0 V, and multicolor display is performed by voltage application. However, for ECD applications, it is quite often that one colored display is always performed and another display is performed as needed.

Object of the invention In view of the above points, the present invention, in a multicolor ECD using an electrolytic solution and an EC substance, by always displaying a color when no voltage is applied, by changing the potential of the electrode, if necessary. It provides an ECD that displays different information in different colors.

SUMMARY OF THE INVENTION The present invention focuses on that a fixed type of a solution electrolyte type electrochromic substance is colored in the state of the spontaneous potential of an electrode, and the fixed type is It was invented by contemplating clever combination with a reducing electrochromic substance that is a solution electrolyte type, but a dissolution type or a precipitation type other than the fixed type. Then, the ECD of the present invention is a solution electrolyte type oxidation electrochromic substance, a conductive layer composed of a reduction electrochromic substance which is a solution electrolyte type and an electrolytic solution, and a voltage for applying an electric field to the conductive layer. An electrode connected to a source, the oxidation electrochromic material is a fixed type in which the electrochromic material is fixed to the electrode before and after the application of the electric field, and is patterned on the electrode. It is fixed and colored when the electrode is in the state of natural potential, the reduction electrochromic substance is a dissolution type in which the electrochromic substance is dissolved in the electrolytic solution before or after the application of the electric field, or The electrochromic substance dissolved in the electrolytic solution before the application of the electric field A deposition type that deposits on the electrode, is dissolved in the electrolyte solution at least before the application of the electric field, and when the electrode is in the state of natural potential, the pattern of the oxidation electrochromic substance The first information is displayed in a first color according to the first color, and when a predetermined potential is applied to the electrode, the first information is displayed in accordance with the pattern of the electric field applied to the electrolytic solution by the electrode. The second information different from the information is displayed in the second color different from the first color.

In the ECD of the present invention configured as described above, the oxidation type EC that is colored when the electrode is in the state of the natural potential (the state in which the equilibrium potential is maintained with respect to the reference electrode with no voltage applied) By using a substance and a colorless reduced EC substance, colored display can always be performed without consuming power, and different information is displayed in different colors by changing the electrode potential only when necessary. To be done. As the EC substance colored in the state of the natural potential, an oxidized EC substance such as Prussian blue K ₄ Fe ^III ₄ [Fe ^II (CN) ₆ ] ₃ can be used, and it can be used on an electrode under certain conditions. By electrolytic synthesis, it is possible to quantitatively form and fix the film. In addition, when the Prussian blue uses an aqueous solution of KCl as an electrolytic solution, the color reaction performed before and after applying an electric field is shown by a color reaction equation. Becomes Further, in this color development reaction formula, the left side of shows the electric field before the electric field is applied, and the right side of the same shows the electric field after the electric field is applied.

The electrolyte of the electrolytic solution forming the conductive layer may be a usual water-soluble supporting electrolyte such as KCl, and can be used at a usual concentration of about 0.1 to 1M.

Embodiments of an ECD of the present invention will be described below with reference to the drawings.

Example 1 FIG. 1 shows a display electrode 1 of the ECD of this example. This electrode 1 comprises a transparent glass substrate 2, a transparent ITO electrode layer 3 and a transparent SiO ₂ insulating layer 4 which are sequentially laminated. On the insulating layer 4, a pattern 5 of the character "purple" and a pattern 6 of the character "blue" are formed. The pattern 5 is formed to a depth reaching the surface of the electrode layer 3. The pattern 6 is formed by forming a depth reaching the surface of the electrode layer 3 and then depositing a Prussian blue thin film on the exposed ITO electrode layer portion by electrolytic synthesis. This electrolytic synthesis was carried out by using a constant current (10 to 50 μA) with the exposed ITO electrode layer portion as a cathode in an equal mixture of Fe ³⁺ (for example, FeCl ₃ ) solution and potassium ferricyanide (K ₃ Fe (CN) ₆ ) solution. (Low current density of about / cm ² ), Prussian blue is quantitatively synthesized. An Ag-AgCl reference electrode 7 is provided at an appropriate position on the insulating layer 4.

The display electrode 1 having such a structure is used as a counter electrode 1 composed of the transparent glass substrate 8 and the transparent ITO electrode layer 9 shown in FIG.
2, a cell is formed by fixing with adhesive 10 via a spacer 11, and heptyl viologen 0.05M and K are added to this cell.
The ECD of this embodiment is configured by enclosing the mixed solution 13 with the electrolytic solution that is an aqueous solution of Cl0.3M. In FIG. 2, the display electrode 1 is shown in a sectional view taken along the line II-II in FIG.

In this ECD, the natural potential of the display electrode 1 is 0.1V vs. SSC.
E, and pattern 6 is blue. Display electrode 1
The potential of was changed to obtain the cyclic voltammogram shown in FIG. Pattern 6 of the Prussian blue thin film is oxidized in the positive potential region and is colored blue, −0.1 V vs.
It becomes transparent at SSCE level. On the other hand, heptyl viologen dissolved in the electrolytic solution is a precipitation type that is dissolved in the electrolytic solution before the application of the electric field but is deposited on the electrode after the application of the electric field, and is −0.5 V vs. SSCE or less. Is reduced to purple and deposited on the pattern 5. Incidentally, when the heptyl viologen is an aqueous solution of KCl as an electrolytic solution, the coloring reaction carried out before and after the application of an electric field is shown by a coloring reaction formula, Becomes Further, in this color development reaction formula, the left side of shows the electric field before application of the electric field, and the right side of the same shows after the electric field is applied.

In the ECD of this example, the range of the potential E of the display electrode 1 which can clearly distinguish the coloring and the erasing (transparent) of each pattern is as follows.

E ≦ −0.5V vs. SSCE Purple (Pattern 5) −0.35V ≦ E ≦ −0.05V vs.SSCE Transparent (Patterns 5 and 6) 0.1V ≦ E vs.SSCE Blue (Pattern 6) The example ECD displays two colors on the same display electrode.

Example 2 In this example, an ECD will be described in which two electrodes facing each other are respectively configured as a first display electrode and a second display electrode. The first display electrode 14 shown in FIG. 4 includes a glass substrate 15 and transparent ITO electrode layers 16a to 16c on the substrate 15.
And SiO ₂ insulating layer 17 are sequentially deposited, and electrode layers 16a to 1
6c is insulated from each other by grooves 18, 19. Electrode layer 16
A pattern A of characters is formed on the insulating layer 17 deposited on b to a depth reaching the surface of the electrode layer 16b.

The second display electrode 20 shown in FIG. 5 includes a glass substrate 21, a transparent ITO electrode layers 22a to 22c and a SiO ₂ insulating layer 2 on the substrate 21.
3 are sequentially deposited, and the electrode layers 22a to 22c are insulated from each other by the grooves 24 and 25. The character pattern B on the insulating layer 23 deposited on the electrode layer 22b is formed in the same manner as in the first embodiment, and is composed of a Prussian blue thin film obtained by electrolytic synthesis. As shown in FIG. 6, the display electrodes 14 and 20 are fixed by an adhesive 26 and a spacer 27 to form a cell. A mixed liquid 28 of heptyl viologen having the same composition as that of the first embodiment and an electrolytic solution is enclosed in this cell to form an ECD. In this ECD, the electrode layers of the display electrodes 14 and 20 shown in FIG. 4 and FIG.
a, 16c and 22a are electrically connected to form a counter electrode,
The electrode layers 16b and 22b are electrically connected to form a working electrode,
The electrode layer 22c is provided so as to serve as a reference electrode. In FIG. 6, the first display electrode 14 and the second display electrode 20 are shown.
Are shown in sectional views taken along line VI-VI in FIGS. 4 and 5, respectively, and reference numerals 30 to 33 correspond to pattern A, and reference numerals 34 and 35 correspond to pattern B.

In the ECD constructed as described above, when no potential is applied to the working electrode, that is, the pattern B is always displayed in blue in the state of the natural potential, and the potential E of the working electrode is changed, the above-mentioned Example 1 is used.
Similarly, the potential E corresponds to the color of the pattern as follows,
Two-color display is performed.

E ≦ −0.5V Purple (display of “STOP” of pattern A) −0.35V ≦ E ≦ −0.05V Transparent (no display) 0.1V ≦ E Blue (display of “GO” of pattern B) ECD of the present invention Is an oxidized EC substance in addition to the EC substance used in each of the above-mentioned examples, and is M in Fe ^III ₄ [M ^II (CN) ₆ ] ₃ .
^II = Ru ^II , ruthenium purple (purple), M ^II = Os ^II
Osmium purple (purple) (however, the color in parentheses indicates the color that each substance fixed on the electrode shows on the electrode in the state of natural potential), and the reduced EC substance is methyl. Use viologen (purple), cyanoviologen (green), p-benzoquinone (yellowish brown), benzylviologen (purple) (however, the color in parentheses represents the color of each substance in the reduced state). You can

EFFECTS OF THE INVENTION According to the present invention, when the electrode is in the state of the natural potential, the first information is given as the first information according to the pattern of the fixed type of the solution electrolyte type of the oxidation electrochromic substance.
Since it is possible to display in different colors, it is possible to always perform colored display without consuming power, and by applying a predetermined potential to the electrodes, display information different from the above colored display in a different color. Therefore, it is most suitable for a display device in which a predetermined color display is always performed and other information is displayed in another color as needed.

Further, the fixed type of the electrolysis type electrochromic material of the solution electrolyte type for performing colored display is patterned and fixed to the electrode, and the solution electrolyte type for displaying different information from this in a different color. Of these, the reducing electrochromic substance, which is a dissolving type or a depositing type, is dissolved in the electrolytic solution at least before the application of the electric field. Therefore, a common electrolytic solution is used for the two types of solution electrolyte type electrochromic materials. Therefore, it is possible to provide a thin display device having a simple structure, although different information can be displayed in different colors by using two kinds of solution electrolyte type electrochromic substances. .

[Brief description of drawings]

FIG. 1 is a perspective view of a display electrode according to the first embodiment of the present invention, FIG. 2 is a longitudinal sectional view of an ECD of the first embodiment, and FIG. 3 is a cyclic voltammogram of the ECD of the first embodiment. 4 and 5 are perspective views of the first and second display electrodes in the second embodiment of the present invention, respectively, and FIG. 6 is a longitudinal sectional view of the ECD of the second embodiment. In the reference numerals used in the drawings, 1 ... Display electrodes 2, 8, 15, 21 ... Glass substrate 3, 9, 16a to 16c, 22a to 22c ... Electrode layer 4, 23 ... Insulating layer 5, 6, A, B ... Pattern 7 ... Reference electrode 12 ... Counter electrode 13, 28 ... Electrolyte solution 14 ... First display electrode 20 ... Second display electrode.

Claims (1)

[Claims] 1. A conductive layer comprising a solution electrolyte type oxidation electrochromic substance, a solution electrolyte type reduction electrochromic substance and an electrolytic solution, and a voltage source for applying an electric field to the conductive layer. The oxidation-type electrochromic substance is a fixed type in which the electrochromic substance is fixed to the electrode before and after the application of the electric field, and the oxidation type electrochromic substance is fixed to the electrode by patterning. The electrode is colored when it is in the state of natural potential, the reduction-type electrochromic substance is a dissolution type or an electric field of which the electrochromic substance is dissolved in the electrolytic solution before and after the application of the electric field. This electrochromic material that had been dissolved in the electrolyte before application was It is a precipitation type that precipitates on the very best, and is dissolved in the electrolytic solution at least before the application of the electric field, and when the electrode is in the state of natural potential, depending on the pattern of the oxidation type electrochromic substance. When the first information is displayed in the first color and a predetermined potential is applied to the electrodes, the first information is defined as the electric field pattern applied to the electrolytic solution by the electrodes. An electrochromic display device in which different second information is displayed in a second color different from the first color.