| 摘要 |
PURPOSE:To check a function, by a method wherein the nunber of revolutions of a fan is detected, and from a signal at a time when the detected number of revolutions exceeds or becomes below a given number of revolutions, an output signal of a detecting circuit for the number of revolutions of the fan, and a logic, it is detected whether or not the transition of the output signal of the detecting circuit for the number of revolutions of the fan occurs within a time of a given pulse width of a pulse signal. CONSTITUTION:A DC voltage A, corresponding to the number of revolutions of a fan, is compared with voltges P1 and P2 corresponding to a maximum and a minumum abnormal number of revolutions, respectively, to generates signals as shown in B and C. Signals D and E are obtained through detection of rise of the signals B and C. Signals F and G, having given pulse widths td1 and td2, are triggered by the signals D and E. Using D terminals of flip flop 8 and 9, a logic of a signal (i) from the detecting circuit for the number of revolutions of a fan to be tested and the signals F and G is taken. Or, if the signal (i) from a circuit to be tested is generated before given times td1 and td2 have elapsed from an abnormal point of time, signals H and J are obtained. If the logical product of the two signals H and H is taken, a signal K is obtained in case the circuit to be tested is normal. |
