Abstract: An optical disc apparatus has a first objective lens for a first optical disc such as a CD and a second objective lens for a second optical disc such as a DVD. The first and second objective lenses are mounted on a base that is transferrable in a direction of radii of the first and second optical discs coaxially installed in the optical disc apparatus. A first center of the first objective lens is located on a first line passing through a center of the first optical disc. On the other hand, a second center of the second objective lens is located on a second line orthogonal to the first line. The first and centers are separated from each other by a predetermined distance.

Abstract: An optical recording/reproducing system for optically recording and reproducing an information signal on and from an optical disc (31) to be recorded with a plurality of track turns includes a light source (52); an optical head (45b) carrying an objective lens (62) for directing a light beam from the light source (52) to one of the track turns, and a tracking servo actuator for displacing the light beam within a movable range to perform both track feed and tracking servo operations for one of the track turns; the optical head (45b) being stationary with respect to the optical disc (31) while performing the track feed and tracking save operations by displacing the light beam in a radial direction of the optical disc; and a recording area on the optical disc having a radial distance equal to or smaller than the movable range of the tracking servo actuator.

Abstract: The control track of the optical disk is scanned by an optical pick-up. Data and clock are detected from the signal obtained by above scanning, and the missing state of the clock is further detected. In addition, the shifting direction relative to the control track of the optical pick-up is detected. When data indicates an error and the clock includes a large missing portion, the optical pick-up is shifted in a direction opposite to the shifting direction thereof. In the case where there is no shifting direction signal, the optical pick-up is shifted in a fixed direction. Such an operation is repeated until no shift is detected. In an alternative implementation, the control track of the optical disk is scanned by the optical pick-up. Data and clock are detected from the signal obtained by above scanning, and the missing state of the clock is further detected. When data indicates an error and the clock includes a large missing portion, the optical pick-up is shifted in a fixed direction.

Abstract: A rotary recording medium comprises a video signal of the same unit repeatedly recorded for N-field period (N is a natural number greater than or equal to 2) for each track turn, a track shift address signal for instructing the existence of forced track shift of a pickup reproducing element, the shifting direction, and the shifting position, recorded on at least one position for one revolution of the rotary recording medium with a constant period regardless of the kind of video signal source of the video signal, where the track shift address signal comprising at least a synchronizing code, rotary recording medium type discriminating code, a kick existence instructing code, and a kick direction instructing code, and divided audio signal parts obtained by dividing an audio signal for every field period of the video signal which is reproduced, successively arranged and recorded according to a scanning locus of the pickup reproducing element upon normal reproduction.

Abstract: A recording and/or reproducing apparatus comprises a signal transducer in the form of a single recording and/or reproducing head. A single step-driving device intermittently steps the head from one track position to another track position on a rotating recording medium to read two separate and alternating sets of tracks. Stepping occurs during a vertical blanking period of a video signal. A synthesized synchronizing signal is generated to compensate for any deficiencies of the synchronizing signal, as originally recorded, and as played back within a reproduced video signal.