Kabushiki Kaisha Toshiba

Akihiko Enomoto

Takashi Koga

Hiroshi Kobata

Minoru Yoneda

A phase detection circuit for detecting the phase shift of an input signal. An A/D converter converts the input signal into first, second and third digital data according to successive three sampling points. A first subtractor subtracts the third data from the second data to produce a first subtraction signal. A second subtractor subtracts the first data from the second data to produce a second subtraction signal. A third subtractor subtracts the second subtraction signal from the first subtraction signal to produce a signal representing the phase shift. An adder adds the first and second subtraction signals together to produce a signal representing the amplitude of the input signal. A converter converts the signal representing the phase shift into a signal representing the absolute value of the phase shift according to the signals representing the phase shift and the amplitude.

Phase detector circuit for periodic signal using three sampling data

A DC motor is supplied, from a motor driver, with a brake voltage constituted by a forward drive voltage, a reverse drive voltage, and a stop voltage of a zero potential level. An operational current of the motor driver is supplied to a low-pass filter whose output is supplied to first and second sample and hold (S/H) circuits. The first S/H circuit performs its sampling operation after a minute period of time in which the brake voltage goes through a polarity inversion from the reverse drive voltage to the forward drive voltage. The second S/H circuit performs its sampling operation after a minute period of time in which the voltage applied is changed from the forward drive voltage to the reverse drive voltage. The outputs or sampled values of both S/H circuits are compared with each other by a comparator. When the sampled values equal each other, i.e., when the number of rotations of the motor becomes zero, the comparator outputs a coincidence pulse. This pulse is supplied to a stop detector. When detecting this coincidence pulse a predetermined number of times in a row, the stop detector determines that the number of rotations of the motor has become zero.

DC motor stop detector and DC motor brake apparatus

A circuit for adjusting a picture quality by processing a digital video signal. A digital filter receives the digital video signal and extracts a high-frequency component therefrom. A first waveform-shaping element wave-shapes the high-frequency component to provide a noise cancel signal for canceling the noise. A second waveform-shaping element wave-shapes the high-frequency component to provide a contour compensation signal for compensating a contour of a picture. An adder adds the digital video signal, the noise cancel signal and the contour compensation signal to provide a signal with adjusted picture quality.

Picture quality adjusting circuit with fir filter for digital processing

A control system for an optical disc information reproducing apparatus in which information data stored in an optical disc is read out during a rotation of the optical disc by a light spot of a light beam. The system includes a laser device for generating the light beam, a device such a turntable for rotatably supporting the optical disc or a pickup device for relatively moving the optical disc and the light spot of the light beam, a photoelectric transducer responsive to the light beam reflected from the optical disc for reproducing the information data from the optical disc during the rotation of the optical disc, the photoelectric transducer producing an electrical signal corresponding to the information data, a circuit for deriving a servo control signal from the reproduced signal, a circuit for modulating the servo control signal to a pulse width modulation (PWM) signal, a device such a turntable drive motor or a pickup transfer motor responsive to the PWM signal for driving the turntable or the pickup device, a circuit for producing a response control signal, and a drive circuit for applying the turntable motor or the pickup transfer motor with a power supply voltage which is changeable in response to the response control signal.

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Tokyo, Japan

Akihiko Enomoto