| 摘要 |
<p>PURPOSE:To increase reliability for fail-safe of a retreat detecting circuit for a coach by utilizing a Gray code counter. CONSTITUTION:Logic speed signals TGX, TGY with respect to a coach speed are applied to synchronizing circuits 13-16 through speed signal latch circuit 11, 12. Synchronizing pulses P1-P4 which are output signals of the synchronizing circuits are added by a NOR gate 17 as a driving pulse Tcp sent to a Gray code counter 18. The Gray code counter is consisting of D flip-flop circuits 21, 22 which are connected in series, a NOR gate 23 for feed back and a NAND gate 24 for controlling. When a control signal CT has arrived at the NAND gate 24 for controlling, the flip-flop outputs Gray code signals Z1, Z2 of 2 bits. When the coach retreats, a truth valve formed by latch signals D1, D2 and another truth value formed by the outputs Z1, Z2 of the counter 18 coincides.</p> |
