CX-977
3) Carriage Servo system
The Carriage Servo inputs low-frequency-component output (lens position information) of the tracking equalizer into
the carriage equalizer, then, after it has earned certain amount of gain, it outputs a drive signals from the LSI. Further,
such drive signals are applied to the carriage motor via the driver.
Specifically, the system works as follows. That is, entire body of the pickup needs to move to the forward direction
when the lens offset reaches certain level during Play. So, the gain of the equalizer is set in such manner that the
equalizer constantly outputs higher voltage than the starting-up voltage of the carriage motor when such condition
occurs. Practically, the system satisfies such requirement in such manner that the Servo LSI outputs the drive voltage
only when the equalizer's output exceeds the specific level of threshold.
To minimize power consumption, and to stabilize operations, the level of threshold is pre-set slightly higher than the
starting-up voltage of the motor. Waveforms of output of this drive voltage take pulse shape.
Fig. 14: Block diagram of Carriage Servo circuit
14 |
ACEC
