| 摘要 |
A digital control for the d.c. motor in cine equipment has the motor speed signals derived from a light beam interrupted by a toothed wheel coupled to the motor. The signal pulses are processed by counters and compared with reference counts using comparator circuits and a ROM to generate correction signals for the motor speed. The control ensures that the actual speed is just greater than a reference value. If the speed drops, i.e. the film tension slows the drive or snags, the drive can be inhibited to prevent damage to the drive motor or the film, and to preserve the batteries. The control is provided on integrated circuits with a low power drain and a simple and low cost layout. |
