Hitachi, Ltd.

Yoshio Narita

Kouji Minabe

Kouji Kaniwa

Hiroya Abe

Hideo Nishijima

Teruo Hoshi

Yukinobu Tada

A magnetic recording and reproducing apparatus arranged to use a magnetic tape. The apparatus operates to derive the current taken-up position of the magnetic tape from the signals that are proportional to the rotation frequencies of a capstan motor, a supply reel and a take-up reel. Only when the taken-up position is near the tape end, the apparatus activates LEDs (light emitting elements) for sensing the tape end and photo-transistors (light receiving elements), for sensing the tape end.

Magnetic recording and reproducing apparatus arranged to save electric power consumed in detecting tape end and reduce load on microprocessor

Magnetic recording and reproducing apparatus arranged to save electric

A tracking apparatus for a helical scan magnetic recording/reproducing system includes a rotation speed controller for controlling the rotation speed of a capstan motor which transports a magnetic tape, a speed deviation generator for applying a deviation to the rotation speed, an envelope level detector for detecting the envelope level of a reproduced signal, a memory for storing the value of detection by the envelope level detector, and an envelope level comparator for comparing envelope levels before and after the deviation is applied to the rotation speed, whereby the rotation of the capstan motor is controlled so that the envelope level becomes a value in the vicinity of a maximum value. The tracking apparatus further includes a steady speed deviation detector for detecting a steady speed deviation between a recording apparatus and a reproducing apparatus, and a steady speed deviation corrector for correcting the detected speed deviation.

Recording and reproducing apparatus including a tracking apparatus with

A tracking method and apparatus used in a helical scan magnetic recording/reproducing system is based on an automatic tracking control using an envelope detection signal of a reproduced signal. The tracking apparatus is provided with a circuit for controlling the rotation speed of a capstan motor which transports a magnetic tape, a level comparing circuit for making the comparison for the level of an envelope signal of the reproduced signal, a circuit for applying a predetermined deviation to the rotation speed in accordance with the result of comparison, a circuit for detecting a steady speed deviation between a recording apparatus and a reproducing apparatus from a speed deviation signal generated in the process of the automatic tracking control, and a circuit for correcting the speed deviation.

Tracking method and apparatus used in helical scan magnetic

A motor speed control device includes a frequency signal generating circuit for generating a frequency signal proportional to a rotation frequency of a motor, a frequency measuring circuit for measuring a frequency of the frequency signal, a speed error signal extracting circuit for extracting a speed error signal by operation comparing the frequency of the frequency signal with a predetermined control target period, a filter circuit for eliminating rotation frequency components of the motor contained in the frequency signal or the speed error signal and harmonic components thereof to output another speed error signal, and a speed error signal feedback circuit for feeding-back negatively the other speed error signal from the filter circuit to the motor, in which owing to the fact that the filter circuit has predetermined transfer functions, it suppresses non-uniform components contained in the speed error signal and the phase error signal due to the frequency signal (DFG signal) proportional to the rotation speed of the drum as well as an addition signal of them.

Motor stabilizing control apparatus for use with motors, including for

A control unit of a direct-current motor used in a magnetic recording and reproducing device or the like, which generates a digital error signal by processing a rotational frequency signal (a rotational frequency signal and a rotational phase signal when necessary) detected from a motor to be controlled, and furthermore, obtains a digital correction signal by processing the value of the power source voltage and corrects the digital error signal using the correction signal to compensate power source voltage fluctuation.

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Hitachinaka, Japan

Yoshio Narita