| 摘要 |
PURPOSE:To detect rotation direction and frequency only by one sensor by identifying the rotational direction on the basis of the waveform of an output from a magnetic sensor responds with a prescribed rotary body at the area of a magnetic pole or the like and counting up or down the output of the sensor. CONSTITUTION:The magnetic sensor H responds with respective areas of N and S poles and non-magnetized areas successively arranged on a rotary ring R with equal angles and generates sensor outputs having different waveforms in accordance with the rotational directions through a waveform shaping circuit 1 and differential circuit 2 to supply the outputs to an up/down counter 3. The counted up number or counted down number of the counter 3 is controlled by a signal outputted from an up pulse generating circuit 4 or a down pulse generating circuit 5 in accordance with each rotational direction identifying signal based upon the waveform of the sensor output. Thus, the rotational direction and frequency can be detected only by one sensor, so that a rotation detecting mechanism optimum to a VTR or the like is obtained. |
