JPS5490088A - Indicating apparatus - Google Patents

Abstract

PURPOSE: To prevent deterioration in the contrast of image presentation with extended life of ECD by employing a porous gold body or a fibrous gold electrode for the opposite electrode to increase contact area with an electrolyte and the capacity of electric double layer enough to use resultant charge and discharge reatction for the opposite electrode.

CONSTITUTION: The ECD in which a display electrode 2 and a porous gold opposite electrode press-coated with powdered gold about 1 mm thick are arranged through a spacer 4 is sealed with an electrolyte comprising heptylbiorogen bromide as indication material and a solution of KBr as a support electrolyte. Then, voltage is applied between electrodes 2 and 3 so as to polarize the electrode 2 in negative whereby a purple compound is electrically deposited on the surface thereof to effect an image presentation. At this point, biorogen monocation radical is allowed to deposit on the electrode 2 with a potential difference set at about 400 mV between the electrode and the reference electrode 6. On the other hand, a short-circuit between the electrodes 2 and 3 enables quick erasion of image. At this moment, the potential of the electrode 3 corresponds to the oxygen adsorption potential. Therefore, the potential changes within the range of ±20 mV. This demonstrates that most part of current is provided by charge and discharge through the electric double layer.

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