US 5,182,683 A · Position control of a magnetic head in a magnetic recording and reproducing system

Abstract

A magnetic recording and reproducing apparatus for reproducing information from a track recorded on a magnetic tape made to travel by being driven by a capstan. Even if a track has been recorded in a curved form, a magnetic head is displaced substantially perpendicularly to a rotational axis of a rotating drum in correspondence with the curve so as to trace the track. A signal read from the track by the magnetic head is subjected to envelope detection and is converted to a digital envelope signal. The capstan is driven and controlled such that the intensity of the digital envelope signal becomes substantially maximum. At the same time, a comparison is made between an ideal scanning pattern for the magnetic head stored in advance and the digital envelope signal, the ideal scanning pattern is corrected on the basis of the result of comparison, and the magnetic head is displaced in a substantially perpendicular direction to the rotational axis of the rotating drum so that the intensity of the envelope signal becomes substantially maximum. The magnetic head is affixed to a projecting portion of an annular spring with an air-core bobbin fitted in a central portion thereof and is displaced by magnetic interaction between an energizing coil wound around the bobbin and a permanent magnet disposed inside the air-core bobbin.

A magnetic recording and reproducing system including apparatus for reproducing from a track recorded on a magnetic tape made to travel by being driven by a capstan, said apparatus comprising:

a rotating drum;
a magnetic head provided on said rotating drum in such a manner as to project from an outer peripheral portion thereof by a predetermined amount;
detection means for subjecting a signal read from the track by said magnetic head to envelope detection and converting the signal to a digital envelope signal;
tracking controlling means responsive to the digital envelope signal for controlling the driving by said capstan such that the intensity of the digital envelope signal output from said detection means becomes substantially maximum;
correction means also responsive to the digital envelope signal for outputting a tracking correction signal such that the intensity of the digital envelope signal output from said detection means becomes maximum;
and
magnetic head driving means responsive to the tracking correction signal for causing said magnetic head to be displaced along the rotational axis of said rotating drum on the basis of the tracking correction signal so as to trace the track;
and
wherein said detection means comprises:
a head amplifier for amplifying the signal read from the track by said magnetic head;
an envelope detection circuit for detecting the envelope of the amplified signal;
and
an A/D converter for converting an analog envelope signal to a digital envelope signal;
wherein said correction means further comprises:
a basic waveform memory in which a plurality of scan signal basic waveform data for designating an ideal scanning pattern for the track of said magnetic head are stored;
an inclination correction memory in which a plurality of correction values for correcting an angle of inclination of the ideal scanning pattern with respect to the magnetic tape are stored;
an optimum track moving memory in which a plurality of correction values for correcting a phase of the ideal scanning pattern with respect to the magnetic tape are stored;
a hill-climbing correction memory in which a plurality of displacement values for causing the ideal scanning pattern to be displaced substantially perpendicularly to a scanning direction;
a processor adapted to effect a comparison between the scan signal basic waveform data and the digital envelope signal from said detection means for each predetermined step, and to read appropriate correction values from said inclination correction memory and said optimum track moving memory, respectively, and an appropriate displacement value from said hill-climbing correction memory on the basis of the result of said comparison;
a D/A converter for converting the scan signal basic waveform and the correction values and displacement value read to analog signals, respectively;
and
an adder for adding the analog correction signal and the analog displacement signal to the analog scan signal basic waveform signal so as to generate a tracking correction signal;
and
wherein said magnetic head driving means further comprises:
a yoke;
an upper and lower coaxial annular spring secured to said yoke, the upper annular spring additionally having a projecting portion at the peripheral edge thereof, said magnetic head being affixed to said projecting portion;
an air-core bobbin having an upper portion affixed to a central portion of said annular springs;
a permanent magnet mounted on said yoke disposed in aid air-core bobbin;
and
an energizing coil wound around an outer periphery of said air-core bobbin and adapted to cause said air-core bobbin to be displaced substantially along the rotational axis of said rotating drum upon being subjected to magnetic interaction between said energizing coil and said permanent magnet by means of the tracking correction signal.

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Position control of a magnetic head in a magnetic recording and reproducing system

Life of this patent

Position control of a magnetic head in a magnetic recording and reproducing system

Life of this patent

Abstract

Claims10