| 摘要 |
PURPOSE:To obtain a stable coordinate output, by driving two sets of parallel resistances connected to two sides of a pressure input surface facing oppositing by means of a constant current circuit, detecting the voltage drop of a resister to obtain coordinates and detecting the presence or absence of the writing pressure from the input terminal voltage of the constant current circuit. CONSTITUTION:Two resistance films 10 and 11 inserting a pressure-sensitive plate between them form a square pressure input surface P. Then resistances R1, R2 and R3, R4 are connected to the sides facing opposite by of the films 10 and 11. A power supply E1 is connected between the joint of resistances R1 and R2 and an earth, and the joint between resistances R3 and R4 is grounded via a constant current circuit 13. The voltage drops of the R2 and R3 are detected and amplified 7 and 8, and signals (x) and (y) showing coordinates X and Y are delivered. The input terminal voltage (v) of the circuit 13 is compared 9 with a constant power supply E2. The presence or absence of writing pressure is detected from the level of an output (w) a coordinate signal having a small error during the presence of the writing pressure and to constitut a device preventing the chattering of writing pressure. |
