| 摘要 |
PURPOSE:To obtain an optical information processor capable of satisfactory searching action by producing a focus search signal having high linearity through an LPF after generating digitally a triangular wave voltage signal with use of a shift register. CONSTITUTION:When an output control signal OCV2 is delivered from a focus detecting circuit 14 after application of a power supply, a shift register SL is driven while the signal OCV2 is kept at a high level. The register SL shifts successively the square wave voltage signals V21 supplied from a low frequency pulse generator 21 and delivers shift signals A-F. These signals A-C are added together in a digital form and supplied to a reverse input terminal (-) of a differential amplifier circuit 25. While signals D-F are supplied in the same way to a non-reverse input terminal (+) of the circuit 25. The output V25 of the circuit 25 is turned into a triangular wave signal and then to a focus search signal FSC having a linear change after passing through an LPF26 to be supplied to a focus actuator coil 19. Thus it is possible to obtain an optical information processor which is capable of an extremely satisfactory focus searching action. |
