Pioneer Electronic Corporation

Keiichi Matsumoto

Hiroyuki Hirano

Fumihiko Yokogawa

Toshiyuki Kimura

Akira Haeno

Susumu Niinuma

Takashi Sato

Yoshihiko Watanabe

Minoru Yoshioka

Youichi Ogawa

Yoshiro Nishi

Yoshio Aoyagi

Yoshiro Aoyagi

A disc player comprising a signal pickup unit to read information from a disc on which program information including address information is recorded, the signal pickup unit being movable with respect to the disc, pickup drive means to drive the pickup unit for movement with respect to the disc, and a control circuit including an address memory for storing the newest one of the addresses read from the disc, a counter operative to count addresses at predetermined time intervals for producing a signal representative of an expected address indicative of the position to which the pickup unit is expected to move in the next, the expected address being updated at predetermined time intervals, a detector circuit to produce a signal each time a discrepancy is found to exist between the newest address and the expected address. In response to the signal from the detector circuit, the pickup drive means is actuated to drive the pickup unit for movement to the position dictated by the newest address or the expected address.

Automatic loading disc player

An automatic disc player including a housing, disc carrier means to convey a disc between predetermined playback position and a predetermined withdrawal position ready to be withdrawn out of the housing upon termination of plaback operation, signal generating means for producing control signals to be predominant over various steps of the playback operation, and an electric control circuit responsive to the control signals to control the various steps of the playback operation, the signal generating means comprising position detecting means responsive to movement of the disc to the withdrawal position and operative to produce a signal when the disc being moved away from the playback position reaches the withdrawal position, and playback re-start switch means which is operative to produce a signal in response to slight movement of the disc from the withdrawal position toward the playback position, the control signals to be produced by the signal generating means including signals to control the start of playback operation. The position detecting means and the playback re-start switch means are connected in series with between ground and the control circuit, and the signals to control the start of playback operation include the signal from the playback re-start switch means.

A system for playing back information recorded on a recording disc includes a first servo control system responsive to a tracking error signal, which adjusts the position of an information reading point of a pickup relative to the recording track on the recording disc, and a second servo control system responsive to a synchronizing signal contained in the playback information signal, which adjusts the speed of rotation of the recording disc. The system is further provided with first detection means responsive to the tracking error signal for detecting a condition where the information reading point has moved across a predetermined number of sections of recording track in a radial direction of the recording disc, and a second detection means responsive to the synchronization signal for detecting a condition where the synchronization signal is not read out up to a predetermined number regularly, and a control means for suspending the servo control operation of at least one of the first and second servo control systems in accordance with output signals of the first and second detection means.

Servo apparatus for tracking and rotational speed control

In a three-beam type optical data disk player, beam output disturbances due to an external disturbance such as vibration and the beam output disturbances due to a local defect on the disk are distinguished from each other, and the servo gain is adjusted according to whether the beam output disturbance is due to the external disturbance or due to the local defect, so that the main beam is controlled to correctly follow the track at all times.

Optical disk player capable of distinguishing external disturbances and

An automatic disc player including a housing, disc carrier means to convey a disc between predetermined playback position and a predetermined withdrawal position ready to be withdrawn out of the housing upon termination of playback operation, signal generating means for producing control signals to be predominant over various steps of the playback operation, and an electric control circuit responsive to the control signals to control the various steps of the playback operation, the signal generating means comprising position detecting means responsive to movement of the disc to the withdrawal position and operative to produce a signal when the disc being moved away from the playback position reaches the withdrawal position, and playback re-start switch means which is operative to produce a signal in response to slight movement of the disc from the withdrawal position toward the playback position, the control signals to be produced by the signal generating means including signals to control the start of playback operation. The position detecting means and the playback re-start switch means are connected in series with between ground and the control circuit, and the signals to control the start of playback operation include the signal from the playback re-start switch means.

Tracking servo control system for an information read-out system such as a video disc player system or a compact disc player system, comprises a servo loop switch for opening and closing the tracking servo loop, and a timing control circuit for generating a timing signal for controlling the servo loop switch in accordance with an on-track signal generated from a pickup output signal and zero cross timings of the tracking error signal. In order to control the operation of the servo loop switch, very accurately, a phase shift circuit is provided between a tracking signal generating means and a zero cross detection means, which has substantially the same phase characteristics as that of an equalizer circuit utilized in the tracking servo loop.

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Tokorozawa, Japan

Keiichi Matsumoto