INPUT DEVICE OF INFORMATION ON COORDINATE POSITION

摘要

PURPOSE:To display the locus of a pressured point on a screen with simple constitution by detecting the currents flowing to each electrode in the form of voltages and comparing then with each other to omit the measurement of the current value. CONSTITUTION:Resistances R1 and R2 are provided between an end of a constant current source 8 and terminals 25 and 26 of a tablet; while resistances R3 and R4 are set between the other end of the source 8 and terminals 35 and 36. A differential amplifier 6 compares the voltages drops of resistances R1 and R2 with each other to output the X axis information on a pressured point. While a differential amplifier 62 compares the voltage drops of resistances R3 and R4 with each other to deliver the Y axis information on the pressured point. A differential amplifier 63 adds the voltages produced at the R3 and R4 and outputs them. A comparator 64 compares the output of the amplifier 63 with the threshold voltage supplied through a terminal 68. Then an output is delivered to a terminal 67 only when the output of the amplifier 63 is larger than the threshold voltage. Thus the presence or absence of pressure is decided.