| 摘要 |
An apparatus forming an incremental motion system is described for controllably moving a load from a first position to a second position in a forward mode to track a moving object field in response to an external reference signal. The apparatus moves the load from the second position back to the first position in a reverse mode. A motor having a rotatable shaft supplies the moving force to the lens shuttle. An optical tachometer having a rotating apertured element fixedly secured to the shaft to rotate therewith generates a signal, upon serving each aperture, in each of the forward and return modes. The signals corresponding to served apertures define feedback signals having corresponding frequencies. A forward control circuit is responsive to the frequency of the reference signal and the frequency of the feedback signal in the forward mode to provide a forward control signal to an amplifier which energizes or drives the motor. A return home circuit, responsive to the net number of signals or pulses indicating the angular displacement of the shaft from the first position, is also responsive to the frequency of the feedback signals in the return mode to provide a return control signal to the amplifier. A home lock circuit locks the lens shuttle in the first position upon its return from the second position.
|
