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    OPTICAL DISC DRIVER AND COUNTING OF NUMBER OF TRACKS OF OPTICAL DISC
    5.
    发明专利
    OPTICAL DISC DRIVER AND COUNTING OF NUMBER OF TRACKS OF OPTICAL DISC 失效

    公开(公告)号：JPH04134632A

    公开(公告)日：1992-05-08

    申请号：JP25546690

    申请日：1990-09-27

    Applicant: IBM

    Inventor： KAGAMI NAOYUKI ,  KUBO HIROAKI ,  OKADA KEIICHI

    IPC: G11B7/085

    Abstract: PURPOSE: To prevent a miscount of TES by providing a positive or negative peak level comparator, which generates a positive or negative peak pulse when TES exceeds a prescribed level on the positive or the negative side, and a logic circuit which generates an output pulse when the positive or the negative pulse is alternately inputted. CONSTITUTION: TES is inputted in a window comparator 300 for detecting zero cross detection. This comparator 300 outputs a zero cross pulse when TES is within a prescribed range including the zero level of TES, and no zero cross pulse when TES is not. The zero cross pulse is inputted in a pulse discriminator 301, the output of which is inputted in a track count logic 500. The logic 500 functions so as to generate an output pulse only when a prescribed pulse is inputted in a prescribed sequence; namely, it functions as a logic circuit for counting the number of tracks. Under this structure, the number of tracks can be accurately counted even if a fault or a pre-pit exists on the recording surface of an optical disk or if a noise is generated by other causes.

    OPTICAL DISC DRIVER
    6.
    发明专利
    OPTICAL DISC DRIVER 失效

    公开(公告)号：JPH04134729A

    公开(公告)日：1992-05-08

    申请号：JP25546790

    申请日：1990-09-27

    Applicant: IBM

    Inventor： KAGAMI NAOYUKI ,  KUBO HIROAKI ,  OKADA KEIICHI

    IPC: G11B7/085 ,  G11B7/09 ,  G11B7/095

    Abstract: PURPOSE: To constantly perform a seek operation properly regardless of a seek speed by providing a means for controlling the control gain of a focus control means. CONSTITUTION: An optical head 10 is composed of a coarse actuator 20 and a fine actuator 30, with the coarse actuator 20 driven in the direction of a seek operation by a coarse actuator VCM(voice coil motor) 24. In addition, the coarse actuator 20 is provided with a relative position (RPE) detecting sensor 25, focus error signal(FES) detecting sensor 27, and tracking error signal(TES) detecting sensor 29. Then, with a highspeed seek operation performed for a certain period after the commencement of the seek operation, the control gain of the focus control means during this period is made the same value as the control gain in the period of a track following operation; with the seek operation nearing the completion, a control signal is imparted from a controller 200 to a gain control means 300, lowering the control gain of the focus control means to a prescribed value. Thus, the control of the seek operation can be constantly performed properly.

    DISC MEMORY
    7.
    发明专利
    DISC MEMORY 失效

    公开(公告)号：JPH04146531A

    公开(公告)日：1992-05-20

    申请号：JP26398190

    申请日：1990-10-03

    Applicant: IBM

    Inventor： KAGAMI NAOYUKI ,  KUBO HIROAKI ,  OKADA KEIICHI ,  TAKEKOSHI MAKOTO

    IPC: G11B7/085 ,  G11B21/08

    Abstract: PURPOSE: To prevent a failure in shifting from a seek operation to a track following operation and also a failure of the seek operation by correcting a variation in a feedback amt. at the time of speed control or a variation of a driving signal. CONSTITUTION: A prescribed value is set in a speed profile generator 88 by a controller 200, and a seek in the direction outside a prescribed number of tracks is started. At this time, a timer 400 is simultaneously started to judge whether contents of a track counter 84 is reduced by 100 tracks, and when the 100 tracks are reduced, its required time is measured by the timer 400. In this case, an outside seek TES gain correcting value is evaluated by a prescribed calculating expression to obtain the positive TES gain correcting value if a seek time is shorter than a target time, i.e., a prescribed reference value, and the negative correcting value if larger. By this method, no shifting failure from the seek operation to the track following operation and no failure in the seek operation can be ensured.

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