| 摘要 |
PURPOSE:To raise remarkably an S/N ratio of a reproducing signal by simple constitution by installing on a rotating part a preamplifier for amplifying a reproducing signal obtained from a magnetic head, and executing an electric power supply to this preamplifier, by a photoelectric cell provided on the rotating part. CONSTITUTION:Reproducing signals obtained from magnetic heads 5, 6 at the time of reproducing are amplified immediately by preamplifiers 10, 11, and thereafter, pass through a rotary transformer and sent to a signal processing circuit of the outside of a cylinder. On the other hand, an electric power supply to the preamplifiers 10, 11 is executed in non-contact without using a slip ring, etc., by an electrooptic-photoelectric converting system consisting of a light emitting element 13 and a photoelectric cell 12. In this case, since an electric power obtained from the photoelectric cell 12 is DC, the electric power supply to the preamplifiers 10, 11 can be executed directly without passing through a rectifying circuit, etc., and the constitution of an electric power supply means is simplified in comparison with that which uses an Ac generator utilizing a magnetic variation. |
