| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a switch circuit with no malfunction caused by the touch resistance of switches by parallelly connecting plural switching elements, which are turned on when the outputs of correspondent switches get higher than a prescribed voltage, through resistors. SOLUTION: Resistors (ladder resistors) 7-9 respectively having a prescribed resistance value are provided and a constant voltage is supplied from a power supply terminal 10 to depression type switches 1-3 and transistors 4-6. When a user depresses the switch 2, for example, with the increase of pressure, the contact resistance is reduced and at the same time, the voltage to be applied to the base terminal of the correspondent transistor 5 is increased. Then, at the time point when the contact resistance becomes the prescribed resistance, the prescribed voltage is applied to the base terminal of the transistor 5, the transistor 5 is turned on, and a resistance divided voltage is inputted from an output terminal 11 to the A/D input port of a microcomputer. The microcomputer executes microcomputer processing corresponding to the switch 2 by judging it from this voltage value.</p> |
