TRACKING CONTROL SYSTEM FOR REPRODUCING ELEMENT IN REPRODUCER FOR ELECTRIC CHARGE IMAGE RECORDING

• Main Authors: SAKAGAMI HIROFUMI, YAMAMURA TAKASHI, TAKANASHI RYOYU
• Format: Patent
• Language: English
• Published: 18.12.1989
• Subjects: ELECTRIC COMMUNICATION TECHNIQUE; ELECTRICITY; INFORMATION STORAGE; INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORDCARRIER AND TRANSDUCER; PHYSICS; PICTORIAL COMMUNICATION, e.g. TELEVISION

PURPOSE:To attain excellent reproduction of an information signal from a recording medium with high density by converting a light whose polarized plane is changed corresponding to the electric field strength into a light whose luminous quantity is changed in response to the change in the light polarized face, applying photoelectric conversion by a photodetector and outputting the result as a reproducing signal. CONSTITUTION:The light made incident in a lens 12, that is, a light whose polarized plane is changed in response to the electric charge image of an insulation layer IL of a recording medium D is fed to an analyzer 14 via a beam splitter 11 and a wavelength plate 13. Then the light whose luminous quantity is changed in response to the change in the polarized plane in the incident light is emitted from the analyzer 14, collected by a lens 15 and fed to a split type photodetector PD having photoelectric conversion elements PDa-PDd. Output signals Sa-Sd from the 4 photoelectric conversion elements PDa-PDd of the split type photodetector PD are calculated by adders 19-21 and the result is sent as a reproducing signal from an output terminal 18. Moreover, the output signal from a subtraction circuit 22 is subject to phase compensation by a phase compensation circuit PC and the result is fed to an actuator ACT.