Abstract: An improved charged coupled device time base corrector system to compensate for a change in the phase or frequency of input video signals, as occurs in the playback of a video tape recorder, by changing the nominal delay through the corrector, comprising, in combination, an input feedback circuit and an output feedback circuit. The input feedback circuit includes two cascaded infinite gain circuits, an infinite gain phase detector followed by an infinite gain voltage amplifier which gives an error voltage that controls the frequency of the voltage controlled oscillator (VCO) utilized to control the system delay. The output servo loop always adapts itself to the input error voltage. The VCO is thereby driven at a rate of change of its frequency proportional to the incoming error signal. .

Abstract: A focussing lens servo driving device for an optical information reading device in which the lens is first driven towards the focussed position with a controlling servo circuit operated in an open loop mode. Once the lens has passed a predetermined position an opposition force is produced in dependance on the lens position. The opposition force is gradually reduced and the servo loop is closed when the lens has been turned back to the predetermined position so that stable operation is provided.