Victor Company of Japan, Limited

Shigeru Kawase

Hisao Kinjo

Katsuyuki Shudo

Yoshio Mizuno

Ryo Nishima

A light beam is emitted to an optical disc from an optical pickup. The optical pickup is moved over the optical disc so that a light spot of the light beam crosses tracks formed on the optical disc. Detected are tracking error signals carried by a light beam reflected from the optical disc. Each tracking error signal is detected when the light spot crosses a corresponding track among the tracks formed on the optical disc. Track crossing pulses are generated based on the tracking error signals. Each track crossing pulse is generated for the corresponding track. Measured next is a half period of each track crossing pulse. It is determined whether a defect occurs to each track crossing pulse, based on a latest half period measured at present and an anterior half period measured one half-period before the latest half period. Generated when determined that no defect occurs is an average half period of the latest and the anterior half periods. Generated when determined that the defect occurs is a corrected average half period based on the latest half period and a plurality of anterior half periods measured before the latest half period. A reference half period is generated that indicates a predetermined speed for the optical pickup to move over the optical disc. The optical pickup is then moved at the predetermined speed based on the reference half period and the average half period or the corrected average half period.

Optical disc apparatus and optical-pickup movement control method installed in optical disc apparatus

A magnetic reproducing apparatus of a helical scan type includes a rotary drum on which a magnetic tape is wound along a part of a helix. A first set of a main head and a sub head is mounted on the rotary drum. The main head and the sub head in the first set are positionally close to each other. The main head and the sub head in the first set have a first azimuth angle and a second azimuth angle respectively. A second set of a main head and a sub head is mounted on the rotary drum. The main head and the sub head in the second set are positionally close to each other. The main head and the sub head in the second set have the second azimuth angle and the first azimuth angle respectively. The second set is opposed to the first set. During a special playback process different from a standard playback process, the magnetic tape is continuously fed while one is sequentially selected from among output signals of the main head and the sub head in the first set and output signals of the main head and the sub head in the second set at a period corresponding to a field to generate a first reproduced signal. The first reproduced signal is periodically and selectively delayed and undelayed to minimize differences among timing positions of vertical sync signals in the first reproduced signal. Thereby, the first reproduced signal is converted to a second reproduced signal. Vertical sync signals in the second reproduced signal are replaced by pseudo vertical sync signals.

Magnetic reproducing apparatus of helical scan type

A device for detecting the position of a recording/reproducing element, which is provided with two position detecting elements having the same input/output characteristics and a device for generating a difference signal representing the difference between output signals of the two position detecting elements. Further, the outputs of the position detecting elements vary correspondingly to change in position of the recording/reproducing element in such a manner to be complementary to each other.

Device for detecting the position of a recording/reproducing element

A magnetic head actuator for displacing a magnetic head on a rotary magnetic head drum in a magnetic recording and reproducing apparatus includes a hollow cylindrical yoke housing a permanent magnet and a central pole therein, providing a magnetic circuit having an air gap. A support shaft axially movably extends through the yoke and has opposite ends positioned outside of the yoke. A coil bobbin is attached to the end of the support shaft which is positioned outside of the open end of the yoke. The coil bobbin supports a coil which is axially movably positioned in the air gap. Two parallel resilient suspension support wings are mounted on the yoke and attached respectively to the opposite ends of the support shaft. A magnetic head holder supporting a magnetic head is mounted on the end of the support shaft near the bottom of the yoke. When the coil is energized, the coil bobbin and hence the support shaft are axially moved to displace the magnetic head to a desired track on a magnetic tape around the rotary magnetic head drum. Since the support shaft is supported by the parallel suspension support wings, the magnetic head is held in good contact with the magnetic tape and prevented from being tilted out of a desired azimuth with respect to the magnetic tape. The magnetic head which is positioned near the bottom of the yoke is free from leakage fluxes from the magnetic circuit.

Actuator for displacing a magnetic head

A video signal recording apparatus forms closed loop tracks on a rotary recording medium, and records a video signal amounting to one field on each track so that out of two mutually adjacent tracks making up a track pair, a signal related to an odd (or even) field out of signals which are related to two consecutive fields and constitute a picture is recorded on one track of the track pair and a signal related to an even (or odd) field out of signals which are related to two consecutive fields and constitute a picture is recorded on the other track of the track pair, so that signals amounting to one frame are recorded on the track pair.

Apparatus for recording a video signal of consecutive fields on a pair

A video signal recording apparatus uses a crosstalk component reproduced from an adjacent pre-recorded track to control the position of a track which is newly formed when successively forming closed loop tracks on a rotary recording medium, and records a video signal amounting to one field on each track so that out of two mutually adjacent tracks making up a track pair, a signal related to an odd (or even) field out of signals which are related to two consecutive fields and constitute a picture is recorded on one track of the track pair and a signal related to an even (or odd) field out of signals which are related to two consecutive fields and constitute a picture is recorded on the other track of the track pair, so that signals amounting to one frame are recorded on the track pair.

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Yokohama, Japan

Shigeru Kawase