Document Type and Number:
Japanese Patent JPH0340858
Kind Code:
B2
Abstract:
PURPOSE:To detect coordinates accurately by setting the threshold value of coordinate detection slightly smallr in data check mode than in data latch mode. CONSTITUTION:When an input pen 4 is brought into contact with a tablet 1, a pen switch 4A is closed and a counter 7 is operated by a control circuit 20 and sends its counted value to X and Y electrode driving circuits 2 and 3 through a gate 8 to scan X and Y electrodes. The pen 4 detects a scanning pulse and supplies its output signal to one input terminal of a comparator CP21 through an amplifier 9. The output of a D/A converter 22 for switching threshold values according to the threshold value specifying signal from the circuit 20 is supplied to the other input terminal of the CP21 to change the threshold value of the CP21, and the value of the counter 7 corresponding to the maximum detected value of the pen 4 is latched by a latch circuit 13. When a data check is made, the circuit 20 makes the threshold level slightly smaller and supplies to the CP14 through a gate 12, and the CP14 compares the value of the counter 7 in the rescanning of the pen 4 with the value of the circuit 13 to output a coincidence signal when those values are equal to each other.
Application Number:
JP1273184A
Publication Date:
June 20, 1991
Filing Date:
January 26, 1984
Export Citation:
International Classes:
G06K11/06; G06F3/03; G06F3/041; G06F3/046; G06F3/048; G06F3/0488