| 摘要 |
<p>PROBLEM TO BE SOLVED: To enable efficient power distribution to a fan through pulse control by a method wherein the monitoring of rotation pulse of a fan is effected only when a fan driving voltage is outputted through a monitoring means. SOLUTION: When the input of a fan driving voltage control signal into an input terminal (a) is 'high', a transistor Q2 is conducted, the gate potential of FETQ 1 becomes a low potential and the FETQ 1 is conducted (low impedance condition) to supply a power supply 12V to the fan 1. When the input of a fan driving voltage control signal into the input terminal (a) is 'low', the transistor Q2 becomes non-conductive, the gate potential of the FETQ 1 becomes a high potential and the FETQ 1 becomes non-conductive (high impedance condition) whereby the supply of the power supply 12V for the fan 1 is stopped. The detection of a fan rotation pulse can be effected as the output C of AND of a rotation pulse signal B from the fan 1 and a driving voltage control signal A through an AND circuit 2.</p> |
