Sony Corporation

Tetsuji Nakazawa

Toshio Asai

Kunio Shimizu

Yuji Arataki

Toshiro Ohta

When a data is recorded to a recording medium, a miserasing preventing circuit determines whether or not a track jump is caused by a shock or a scratch. If it is caused by a shock, such as a quantity of light of an optical pick-up is controlled to change a reproducing state, and then the optical pick-up is moved to the rerecording position to start rerecording. As a result, recorded area is not disturbed, and the rerecording control is not performed by a little dust. Thereby, it can be provided an apparatus with high recording efficiency.

Data erasure preventing method and circuit thereof and optical disc apparatus mounting the same

A rotation control apparatus which does not rely upon a drop of a signal is provided. A lower limit frequency and an upper limit frequency calculated based on generation patterns of run length limited codes which may possibly be generated stochastically are set as a frequency variation range. When rotation control is performed based on an error between a frequency of run length limited codes reproduced from a disk and a reference frequency while a PLL circuit is not in a locked condition, the reference frequency is varied between the upper limit frequency and the lower limit frequency. Then, the reference frequency which is currently used for comparison when the PLL circuit is put into a locked condition is stored as a fixed value and used as the reference frequency for later rotation control.

Rotation control apparatus, reproduction apparatus to which rotation control apparatus is applied, and rotation control method

The invention provides a phase locked loop circuit, a reproduction apparatus and a phase locking method by which a capture range and a lock range can be widened. Before a phase locked loop circuit is locked, an output clock of a voltage controlled oscillator is counted with reference to a reference clock of a quartz oscillator, and an error component between run length limited codes reproduced from a disk and the reference clock is extracted. Then, the PLL circuit is constructed based on a result of addition of the counted value of the output clock and the extracted error component. After the phase locked loop circuit is locked, a phase error of the output clock of the voltage controlled oscillator against the run length limited codes reproduced from the disk is detected, and the PLL circuit is constructed based on the detected phase error.

Phase locked loop circuit, reproduction apparatus and phase locking

A phase locked loop circuit for absorbing characteristic variations of phase comparator components beforehand in adjusting mode. With the variations thus adjusted and co-opted, any intrinsic error of the phase comparator is prevented from appearing as a phase difference upon transition from adjusting mode to normal operation mode. The scheme inhibits lock range deviations or capture range variations in normal operation mode, permitting a stable phase locked loop function.

Phase locked loop circuit and reproducing apparatus

Apparatus is provided wherein signals which are reproduced from a record medium and which are supplied to head-phones are selectively attenuated and, concurrently, audio electrical signals produced by a microphone are superimposed onto these attenuated signals. An attenuator is coupled between a record/playback transducer and an amplifier; and a switch exhibits a first condition to short-circuit the attenuator, and a second condition to enable the attenuator to attenuate the signals reproduced by the record/playback transducer and also to superimpose the audio electrical signals produced by the microphone onto the attenuated signals. In one embodiment, a record/reproduce selector selectively establishes either a recording mode, whereby the audio electrical signals produced by the microphone are amplified and supplied to the record/playback transducer, or a reproducing mode, whereby the signals reproduced from the record medium by the record/playback transducer are supplied to the amplifier.

Recording/reproducing apparatus with selective attenuation of reproduced

An operating mode change-over apparatus in a tape recorder includes: a plunger-solenoid having a stationary iron core and a movable iron core movable from a first position in contact with, and a second position spaced from, the stationary iron core; an electric motor; a pinion driven by the electric motor; a rack engageable with and disengageable from the pinion; an operating mode change-over member driven by the rack; a locking lever driven by the movable iron core and holding the engaged condition of the rack and pinion; and a spring for pressing the movable iron core to the stationary iron core, wherein, while the movable iron core is pressed to the stationary iron core, the plunger-solenoid is energized, and the electric motor is driven.

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Kanagawa, Japan

Tetsuji Nakazawa