JPS6010063B2 - display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses an electrolytic solution in which an electrochemically redoxable display material* and a supporting electrolyte are dissolved in an electrochemically inert solvent. The present invention relates to a display device in which electrodes of the present invention are brought into contact with each other.

Such a device is described in the literature (Appl.Ph.Let
t. , 2, 64 (1973)).

This device uses heptyl viologen furomide as a display material, and performs color display and erasure using an electrochemical reaction formula according to the m-th equation below. That is, the biologen compound (which is initially dissolved in the electrolyte in a colorless state)
i) undergoes electrochemical reduction and becomes a cation monoradical, producing a purple-colored, water-insoluble salt (ii), which is deposited on the surface of the display electrode, making color display possible.
On the other hand, since the compound (ii) is reversibly oxidized,
For example, by reversing the channel properties of the display electrode, the initial material (i) can be regenerated and color can be erased. However, since the color display in this device is a radical substance, it is extremely easily self-extinguished by dissolved oxygen in the electrolyte, and unless the dissolved oxygen is sufficiently removed, the memory effect of the displayed image will be impaired. Furthermore, since the reversible reduction potential of electrochemical reactions for displaying and erasing is narrow, the life of the display device cannot be extended unless the voltage applied to the display electrode is regulated and the electrochemical reaction proceeds within the reversible potential region. For this reason, it is necessary to provide a reference electrode for regulating the potential of the display electrode described above in addition to the counter electrode of the display electrode, and the drive circuit of the device becomes extremely complicated, resulting in various drawbacks and problems. The inventors have a problem.
In order to solve the above problem, first, a reversible redox reaction of the following formula '2' was carried out using iodine ions and polycyclic compound ions X, and a black and colored product (X13) was precipitated on the top of the display. , by erasing the color display,
A simpler device with longer memory time is provided.

The present invention uses 4-benzoylpyridinium ion as a polycyclic compound ion based on the same principle as the previously proposed device, and has a longer mound storage time, as well as excellent display with high color density. It is an object of the present invention to provide a display device that can provide functions.

To explain in more detail the display and erasing principle of the present invention, this display is based on the above equation (2), in which iodine (12) generated at the top of the display by an electrochemical oxidation reaction of iodine ions (1) interacts with iodine ions near the electrodes. Cyclic nitrogen compound cation X
+ forms a stable body X13, and since the complex is insoluble in an aqueous solution, it stays on the display surface, making it possible to display black and other colors, and at the same time having a display memory function.

On the other hand, by reversing the polarity of the electrode, the precipitated collar body is reversibly reduced and returns to the initial iodine ions and cyclonitrogen compound cations, making it possible to erase the color. Hereinafter, the present invention will be explained in more detail using Examples.

1 and 2 show an embodiment of the display device of the present invention, with FIG. 1 being a plan view thereof and FIG. 2 being a sectional view taken along the line 11r. Reference numeral 1 denotes a transparent substrate made of glass or the like, 2 a silver electrode for a counter electrode, and 3 a mask which allows only the displayed portion to be seen through transmission.

4 is the display pole pattern Sn02, ln203, Pt, A
It is a transparent electrode using U or the like, and has display cements 4a to 4g as shown in FIG.

Each display segment communicates with external terminals 4a''-4g'' via lead portions 4a'-4g'. Each lead portion is covered with an insulating film (Si02AI203, etc.) 7.
5 is a spacer, and 6 is an injection hole for electrolyte 8, which is sealed after the electrolyte is injected.

The electrolytic solution 8 used here is, for example, an aqueous solution containing a halogenated polycyclic nitrogen compound and KI.

In this display device, when the display electrode 4 is used as a positive electrode and the counter silver electrode is used as a negative electrode, and a DC voltage is applied between the two electrodes, an anchor body consisting of iodine and a multi-hata cyclic nitrogen compound is deposited on the positive electrode, and the colored substance is An image is displayed, and even after the applied voltage is removed, the displayed image remains in a memorized state.

When a reverse voltage is applied between the two electrodes, the key on the positive electrode dissociates into individual ions and dissolves in the electrolyte, erasing the image. As a display material having a reversible oxidation-reduction function, it is preferable that the contrast (rate of change in light transmittance) of image display becomes larger when a certain amount of electricity is applied.
Moreover, the longer the image storage time, the more preferable.

The inventors conducted a property comparison test regarding such properties between the multihata cyclic nitrogen compound based on the present invention and the heterocyclic nitrogen compound previously proposed by the present inventors. The results are shown in Table 1.

Table 1 Here, compounds 1 to 4 are the polycyclic nitrogen compounds proposed above, and compounds 5 to 9 are the polycyclic nitrogen compounds according to the present invention.

Each actual value is N, which is one of the conventional heterocyclic nitrogen compounds.
- Comparisons are made based on the characteristic values of ethylpyridinium iodide in terms of their ratios.

The electrolytic solution used here was a halogenated heterocyclic nitrogen compound 0.1Mol/so (0.1Mole/so that does not dissolve is in a saturated state), KIOO. It is an aqueous solution containing 2Mol'.

Furthermore, the spacing between the electrodes of the test cells was set to be the same. The post-recording time ratio shown in the first column of Table 1 refers to the same amount of electricity (10mc
It represents the ratio of the time required for erasing until the light transmittance in the same area reaches a certain value after power is applied to display the image, and then the voltage application is removed.

In addition, the light transmittance change ratio in the second column refers to the same amount of electricity**(l
owc') represents the ratio of light transmittance in the same area when current is applied.

As is clear from Table 1, the heterocyclic nitrogen compound having penzoylpyridinium in the basic molecular skeleton based on the present invention has superior performance compared to that proposed previously. .

In particular, the basic skeleton of the molecule is 2-penzoylpyridinium,
In the case of 3-benzoylpyridinium or 4-benzoylpyridinium, when these were compared, the 4-benzoylpyridinium-based heterocyclic nitrogen compound was superior.

Further, although Table 1 shows examples of iodine or bromide as the halogen salt of the heterocyclic nitrogen compound, other halogen elements can also be used.

Other typical examples of substances according to the present invention include those shown in Table 2 as benzoylpyridinium ion species.

Table 2 In the present invention, substituents other than those exemplified may be used for R2 in the formula.

The heterocyclic nitrogen compound according to the present invention can be produced by a conventional method, but when R is an alkyl group, the synthesis yield tends to be higher than when using other substituents.

Furthermore, due to the characteristics, when R is an alkyl group, the solubility in the electrolyte tends to decrease as the number of carbon atoms in the alkyl group increases.

In this case, an alkyl group having preferably 1 to 8 carbon atoms was preferable. As described above, the present invention has excellent display contrast, long image storage time,
It is possible to provide a display device using an electrochemical method that is highly stable over a lifetime.

Furthermore, this device can be widely applied as electrochemically controllable light variable elements such as color filters and light modulators, and has great industrial value.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a display device in an embodiment of the present invention;
FIG. 2 is a sectional view taken along line 1-1' of FIG. 1. 1...Transparent substrate, 2...Silver electrode, 8...
- An aqueous solution containing a halogenated double cyclic nitrogen compound and KI. Figure 1 Figure 2

Claims (1)

[Claims] 1. As display materials that can be electrochemically reversibly redoxed, there are at least iodine ions and 4-benzoylpyridinium ions represented by the following formula ▲ mathematical formulas, chemical formulas, tables, etc. ▼ (in the formula, R_1 is A display device characterized in that an alkyl group (R_2 represents a chloro group or a methyl group) is contained in an electrolytic solution.