| 摘要 |
<p>PURPOSE:To obtain a stable, accurate detection signal by fixing the number of projection pulses to each reflecting plate to 3 or 4 without reference to a speed by utilizing distance pulses, and minimizing projection pulses to places other than reflecting plates. CONSTITUTION:A distance pulse generator 2 coupled directly with wheels 1 generates distance pulses (a) at constant intervals of distance proportional to the rotating speed of the wheel 1, those pulses are passed through a waveform shaping circuit 3, and the pulse intervals are so adjusted by a variable counter circuit 4 so that three or four pulses are generated to the width of the reflecting plate 10. The pulses (b) are passed through a differential pulse generating circuit 6 and increased in power level by a driver 7, so that a light emitting element 8 emits light pulses (c). A photodetection part detects and obtains only pulses synchronized with the synchronizing pulses (b) among emitted light pulses (d) through a synchronous detector 16. Then, a decision circuit 14 outputs a detection signal indicating that there is the reflecting plate from a terminal 15 with two continuous pulses.</p> |
