PURPOSE: To eliminate errors resulting from the variance of the capacity of an electrostatic capacity detecting type appointed position detecting device, by newly installing a means which automatically corrects the capacity of an electrode at the appointing section.
CONSTITUTION: When an electric power supply switch SW1 is turned on, a differentiating pulse P1 is generated and the control circuit of an MPU8 is reset, and then, a changeover switch 15 is set to the output port side. When the contact 3a of an appointing electrode changeover switch 3 is connected with, for instance, a contact 3c to select one of the appointing electrodes of an appointing device PN thereafter, the output of an appointing electrode TCH1 is supplied to an appointment detecting section 1 and a correcting circuit 4. By performing capacity correcting operations by successively turning on the elements S1,S2,W of a switch 5 in the correcting circuit 4 under this condition, a point at which the output level from the appointment detecting section 1 becomes the maximum is searched. The corrected value of a correcting capacitor when the maximum output level is obtained is stored in an address RAM14 corresponding to the appointing electrode at this time.
YOSHIKAWA KAZUO
ASANO TOORU
TAKIZAWA HIDEAKI
