Recording track eccentricity compensation method and means
AssigneeGraham Magnetics Incorporated
InventorWilliam A. Manly
Life of this patent
Estimating the term…
Abstract
Playback method and apparatus compensate exactly for both tracking and speed errors due to any eccentricity in the information track on a rotating recording member during playback by moving the read head in a circular path having the same radius, angular velocity and phase as the circle of eccentricity of the track.
Claims20
The method of compensating for eccentricity in a circular or spiral recording track on a recording member rotating about an axis during playback comprising the steps of
- A. moving the playback transducer in a circular path opposite the track on the recording member,
- B. adjusting the radius of the circular path to equal the distance between the axis of rotation of the recording member and the center of the eccentric track, and
- C. controlling the movement of the transducer in phase to correspond to the phase angle of the instantaneous position of the track center about the axis of rotation of the recording member.
The method of eliminating both amplitude and frequency or time variations in the output signal from a playback transducer as a result of reading from an eccentric track on a rotating recording member rotating about an axis during playback comprising the steps of
- A. determining the magnitude of eccentricity-causing amplitude or frequency modulation in the signal from a playback transducer reading from the track,
- B. determining the difference in phase between said modulation and the rotation of the recording member, and
- C. moving the playback transducer in a circle whose radius is proportional to said modulation magnitude and whose phase is equal to the phase of said modulation.
The method of compensating for both tracking and speed errors when reading from a rotating recording member having an eccentric track whose center moves about the center of rotation along a circle of eccentricity comprising the steps of
- A. mounting the playback transducer for movement in the plane of the recording member, and
- B. moving the transducer in a circular path having the same radius, angular velocity and phase as the circle of eccentricity.
A system for compensating for eccentricity in a circular or spiral recording track on a rotating recording member comprising
- A. means for mounting the recording member about an axis,
- B. a playback transducer movably positioned opposite the recording track,
- C. means for moving the playback transducer in a circular path opposite the track in the plane of the recording member,
- D. means for adjusting the radius of the circular path to equal the distance between said axis of rotation of the recording member and the center of the eccentric track, and
- E. means for controlling the movement of the transducer in phase to correspond to the phase of the instantaneous position of the track center about said axis of rotation.
A system for compensating for both the tracking and speed errors when reading from a rotating recording member having an eccentric track whose center moves about the center of rotation along a circle of eccentricity comprising
- A. means for rotating the recording member about an axis,
- B. a playback transducer,
- C. means for positioning the playback transducer opposite the recording member for movement in the plane of the recording member, and
- D. means for moving the transducer in a circular path in said plane having the same radius, angular velocity and phase as the circle of eccentricity.
A system for compensating for eccentricity in the recording track on a rotatable recording member during playback comprising
- A. means for rotating the recording member about an axis,
- B. a playback transducer,
- C. means for mounting the playback transducer opposite the recording member for movement in the plane of the recording member,
- D. means for determining the magnitude of eccentricity-causing amplitude or frequency modulation in the signal from the transducer as it reads from the track,
- E. means for determining the difference in phase between said modulation and the rotation of the recording member,
- F. means for moving the playback transducer in a circle in the plane of the recording member whose radius is proportional to said modulation magnitude, and
- G. means for adjusting the phase of the moving means in accordance with said phase difference to be equal to the phase of said modulation.
Dependencies are inferred from the claim text.