Canon Kabushiki Kaisha

Yoshiyuki Sasaki

Yasuyuki Tanaka

Shinichi Yamashita

Makoto Gohda

Kazuna Kobayashi

In an information signal recording and reproducing apparatus, reproduced data is equalized by an equalizer and a clock signal synchronized in phase with the reproduced data is generated. An equalizing characteristic of the equalizer is controlled according to a difference in frequency between the clock signal and the reproduced data, and a generating operation for the clock signal is controlled according to a phase difference between the clock signal and the reproduced data. The clock signal thus can be stably generated without being affected by variations of temperature and variations due to aging. The equalizer thus has an adequate equalizing characteristic. The apparatus includes a recording mode and a reproduction mode. In the recording mode, a recording clock signal is generated by a clock signal generating circuit and a digital signal is recorded by using the recording clock signal. In the reproduction mode, a reproducing clock signal which is synchronized in phase with a reproduced digital signal is generated by the clock signal generating circuit and the digital signal is reproduced by using the reproducing clock signal.

Reproducing apparatus capable of generating clock signal synchronized in phase with reproduced data

An apparatus is arranged to perform an equalizing process for equalizing an input signal including a video signal, to obtain a reproduced video signal by performing reproducing processes on the signal equalized and to vary the equalizing characteristic of the equalizing process during a period other than a period during which the reproduced video signal is in process of being obtained. The arrangement enables the apparatus to prevent the reproduced video signal from being affected by changes of the equalizing characteristic and to optimize the equalizing characteristic without impairing the quality of reproduced images.

Reproducing apparatus capable of controlling reproduction equalizing characteristic

A reproduction apparatus for reproducing data, from a magnetic recording medium on which digital data is recorded, using a magnetic head, which includes a head amplifier which amplifies a reproduced signal obtained from the magnetic head, and has controllable resonance characteristics at least with respect to the magnetic head; an error correction decoding circuit for performing error correction by performing error detection of the reproduced signal obtained from the head amplifier; and a head amplifier control circuit for controlling the resonance characteristics of the head amplifier on the basis of an error detection signal obtained from the error correction decoding circuit.

Reproduction apparatus having reduced decoding error rate

A specific pattern in an inputted digital signal is detected and the input digital signal is sampled and held in accordance with such a detection output. A clock whose phase is synchronized with the input digital signal is generated on the basis of the sampling output. With such a construction as mentioned above, the phase of the clock can be optimally controlled by a simple construction. The clock can be precisely extracted from the input digital signal, so that the operation of a circuit is also stable.

Apparatus for generating a signal whose phase is synchronized with an

A reproducing apparatus having a phase-locked loop for controlling recording medium transport has selectable normal and search reproduction modes and is settable to the search reproduction mode upon an output of the phase-locked loop obtained in operation of the apparatus in the normal reproduction mode.

Reproducing apparatus settable in a search reproduction mode from

A recording apparatus includes a first power supply having a first output voltage, a second power supply having a second output voltage different from the first output voltage, and a recording circuit for recording input digital data on a recording medium selectively using the first power supply or the second power supply. The recording circuit selectively uses the first power supply or the second power supply in accordance with a state of the input digital data. It is thereby possible to reduce power consumption in the circuitry of the apparatus during recording.

Recording apparatus wherein the recording circuit uses a first power

In equalizing a reproduced signal with an equalizer having a variable equalizing characteristic, a decision as to whether or not the equalizing characteristic is to be varied is made by using the reproduced signal. For example, the frequency of performing an equalizing characteristic varying action is controlled according to an error rate in the reproduced signal. By virtue of this control, the equalizing characteristic can be quickly optimized in the event of a high error rate and, in a case where the error rate is low, the equalizing process can be stably carried out. Further, the equalizing characteristic is arranged to be varied while the level of the reproduced signal is in the neighborhood of a predetermined level, so that the equalizing characteristic can be optimized for such a signal that is most vulnerable to an adverse effect of the varying of the equalizing characteristic.

Reproducing apparatus including equalizing means which equalizes a

The present invention is applicable to an apparatus which is arranged to reproduce a signal from a recording medium by using a plurality of heads each having a different azimuth angle and which includes a PLL circuit formed by an oscillator, a phase-difference detector for detecting a phase difference between an output clock signal of the oscillator and the reproduced signal, and a loop filter for receiving an output of the phase-difference detector. The present invention generates a clock signal phase-synchronized with the reproduced signal, by detecting an oscillation frequency error of the oscillator relative to a target frequency, integrating the oscillation frequency error together with an output of the loop filter to provide an integral output, adding the integral output to the output of the loop filter and inputting an addition result to the oscillator, and varying an operation for detecting the oscillation frequency error, according to the azimuth angle of each of the plurality of heads.

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Yokohama, Japan

Yoshiyuki Sasaki