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    • 8. 发明专利
    • OPTICAL DISK DEVICE
    • JPH0291818A
    • 1990-03-30
    • JP24236088
    • 1988-09-29
    • JAPAN BROADCASTING CORP
    • TOKUMARU HARUKI
    • G11B7/00G11B7/0045
    • PURPOSE:To make the S/N ratio of a reproducing signal excellent and to reduce the distortion of waveform by previously setting the radius of an optical disk which rotates at a constant angular velocity and an optimum duty ratio in an environmental temperature and controlling a recording signal. CONSTITUTION:Data on the optimum duty ratio corresponding to the position of radius in each environmental temperature under which the optical disk device is used is previously obtained and stored in a ROM 11. The environmental temperature at the time of recording and the position of the radius of the disk are detected by a temperature sensor 9 and a disk radius position sensor 7 and transferred to a CPU 5 through A/D converters 8 and 10. According to the transferred data, the CPU 5 reads out the duty ratio in which the distortion of waveform is minimum from the ROM 11 and inputs it in a comparator 2. An output from the comparator 2 is inputted in a duty ratio detection circuit 3 and the detection output from the circuit 3 is supplied to the CPU 5, where it is compared with the data on the duty ratio from the ROM 11, and the compared result is returned to the comparator 2 to control the duty ratio. The duty ratio of the actual recording signal is controlled to be equal to the optimum value, whereas the S/N ratio of the reproducing signal is made excellent.
    • 9. 发明专利
    • MAGNETO-OPTICAL RECORDING AND REPRODUCING DEVICE
    • JPH01100755A
    • 1989-04-19
    • JP25729387
    • 1987-10-14
    • JAPAN BROADCASTING CORP
    • TOKUMARU HARUKINOMURA TATSUOTAI KAZUHIKO
    • G11B11/10G11B7/085G11B11/105
    • PURPOSE:To realize recording and reproduction with high density by arranging an objective lens between the light reflecting plane of a rotary polygonal mirror and a magneto-optical recording medium, and enabling the magneto-optical recording medium to be scanned by a convergent spot. CONSTITUTION:A tape shape recording medium 1 is the one is which a magneto- optical recording material layer of Tb-Fe and Tb-Fe-Co, etc., is provided on a resin film with low rigidity and with heat resistance by vapor-deposition or sputtering, and a guide groove for tracking is formed, and it is wound on a supplying reel 13. Laser beams emitted from a fixed optical system A2 and a fixed optical system B3 arranged oppositely to the side of the tape shape recording medium 1 are reflected on the rotary polygonal mirror 6, and each of them is made incident on actuators 4 and 5 incorporating the objective lenses, respectively, and is converged on the recording medium 1, then, it is recorded or reproduced. The actuators 4 and 5 are supported by brackets extending from the fixed optical systems A and B, respectively, and perform a focusing or a tracking function by moving the objective lens. In such a way, it is possible to perform the recording with high density.