| 摘要 |
<p>PROBLEM TO BE SOLVED: To discriminate the difference in depression area and prevent the shift of depression detection position by measuring and storing a voltage which is proportional to the resistance value of a resistance film when there is no depression and comparing it with a voltage which is proportional to the resistance value of the resistance film at the time of depression. SOLUTION: This circuit is provided with a constant current source 10 which supplies a constant current I,a touch detecting circuit 3 which detects the contact of resistance films 20 and 30. A memory 13 stores the values of the voltages across the resistance film 20 and 30 to which the constant current source 10 is connected at the time of no depression and a CPU compares the voltage values stored in the memory 13 with the values of voltages across the resistance films 20 and 30 to which the constant current source 10 is connected at the time of depression to discriminate whether the depression area is large or small. Further, the detection shift of depression position due to a difference in depression area is preferably corrected with the voltage values varying with the difference between the resistance films 20 and 30 to which the constant current source 10 is connected. Consequently, the depression area becomes large and the two resistance films 20 and 30 become partially parallel connection, so that the phenomenon that the total resistance value decreases can be detected.</p> |
