Electric Equivalent Circuit in Coloration Process of ECD and the Application for Circuit Design

Abstract

It is very important in a circuit design that a designer numerically can calculate an electric characteristic of ECD (Electrochromic Display). An equivalent circuit using resistor and condenser was proposed in the coloration process until now. But it did not effectively simulate V-I characteristic of ECD when applied voltage was changed.
An improved electric equivalent circuit of WO₃ type ECD is suggested and for the application, optimum design of driving circuit is described.
The equivalent circuit connects diode and condenser in series and diode in parallel. The former diode and condenser correspond to coloration current. The latter diode corresponds to leakage current. It can simulate V-I characteristic and optical density even if applied voltage is changed. Calculation results of coloration current and density are in good agreement with the experiments. Finally, optimum capacity of the driving circuit of the grounding fault indicator is calculated.