| 摘要 |
<p>PURPOSE:To obtain an automatic power source opening/closing device by turning on a power source of a terminal equipment at the time point when a signal is transferred from a host computer, and cutting off the power source at the time point when a prescribed time has elapsed, after the time point when the signal has come not to be transferred. CONSTITUTION:In order to cut off a power source 13 of a terminal equipment 6, a signal Sx is stopped for the time exceeding the time Tx when a logic level goes to L, through an optical connector 3 from a host computer. As a result, a count value of a counter circuit 15 which is counting a clock pulse (ck) from the time point when the signal Sx has dropped to L in the end exceeds a count value corresponding to an output terminal Qx. Therefore, the output of the Qx changes H from L and an FF 17 is reset. Accordingly, the output of a driver 20 rises to H and an excitation of a relay coil 18b is released, and a normally opening contact 18a which has been closed is opened, therefore, the power source 13 which is turned on to the terminal equipment 6 is cut off, and the operation is stopped.</p> |
