Memory disc pack drive having accurate read/write head positioning

Claim 2

Apparatus for use in conjunction with a predetermined data pattern applied to a data storage surface in reporting the location of a data transfer device with respect to a desired positioning thereof relative to said data storage surface, comprising means responsive to a reading by said data transfer device of said data pattern by generating therefrom a signal having at least a pair of states whose relationship to one another is indicative of the location of said data transfer device with respect to said desired positioning, and comparison means for receiving said pair of signal states and comparing the same to provide an output reporting said location of said data transfer device with respect to said desired positioning wherein said means for generating a signal in response to a reading by said transfer device of said data pattern generates such a signal having a cyclical waveform with the relationship of predetermined cycle positions thereof providing said indication of said location of said data transfer device with respect to said desired positioning, wherein said comparison means includes means for superimposing signals representative of said predetermined cycle positions on one another to provide said comparison of the same.

Claim 3

The apparatus of claim 1 for reporting the location of a data transfer device with respect to a desired positioning thereof wherein said output provided by said comparison means is a visual display output from which an operator can perceive the relationship of said superimposed signals to obtain said indication of the location of said data transfer device with respect to said desired positioning.

Claim 4

The apparatus of claim 2 for reporting the location of a data transfer device with respect to a desired positioning thereof wherein the relationship of said superimposed signals providing said indication of said location with respect to said desired positioning is the displacement of one of said signals from the other.

Claim 5

Apparatus for use in conjunction with a predetermined data pattern applied to a data storage surface in reporting the location of a data transfer device with respect to a desired positioning thereof relative to said data storage surface, comprising means responsive to a reading by said data transfer device of said data pattern by generating therefrom a signal having at least one pair of states whose relationship to one another is indicative of the location of said data transfer device with respect to said desired positioning, and comparison means for receiving said pair of signal states and comparing the same to provide an output reporting said location of said data transfer device with respect to said desired positioning, and wherein said desired positioning is the proper position of said transfer device with respect to said surface for transferring data to a predetermined track location thereon, said predetermined data pattern is one applied to said data storage surface on a test track which is superimposed spacially along said track location, and said means for generating a signal in response to a reading by said transfer device of said data pattern generates such a signal having a cyclical waveform whose amplitude at any given time is a function of the location of said transfer device relative to said data pattern on said test track and hence relative to said desired track positioning wherein said data storage surface is mounted for rotation for the reading therefrom during its rotation of data thereon by said data transfer device; said test track having said predetermined data pattern is generally circular and eccentric with respect to the axis of rotation of said surface whereby upon the rotation of said surface with respect to said transfer device, the distance of said data pattern from said transfer device will vary cyclically with each revolution of said surface to cause a corresponding cyclical variation in the amplitude of the signal generated from said pattern by said signal generating means; and said comparison means includes means for superimposing signal representative of one-half cycle portions of said signal generated from said data pattern on one another to provide said comparison of the same.

Claim 6

Apparatus for use in conjunction with a predetermined data pattern applied to a data storage surface in reporting the location of a data transfer device with respect to a desired positioning thereof relative to said data storage surface, comprising means responsive to a reading by said data transfer device of said data pattern by generating therefrom a signal having at least one pair of states whose relationship to one another is indicative of the location of said data transfer device with respect to said desired positioning, and comparison means for receiving said pair of signal states and comparing the same to provide an output reporting said location of said data transfer device with respect to said desired positioning, and wherein said desired positioning is the proper position of said transfer device with respect to said surface for transferring data to a predetermined track location thereon, said predetermined data pattern is one applied to said data storage surface on a test track which is superimposed spacially along said track location, and said means for generating a signal in response to a reading by said transfer device of said data pattern generates such a signal having a cyclical waveform whose amplitude at any given time is a function of the location of said transfer device relative to said data pattern on said test track and hence relative to said desired track positioning wherein said data storage surface is mounted for rotation for the reading therefrom during its rotation of data thereon by said data transfer device; said test track having said predetermined data pattern is generally circular and eccentric with respect to the axis of rotation of said surface whereby upon the rotation of said surface with respect to said transfer device, the distance of said data pattern from said transfer device will vary cyclically with each revolution of said surface to cause a corresponding cyclical variation in the amplitude of the signal generated from said pattern by said signal generating means; and said comparison means includes means for superimposing signal representative of one-half cycle portions of said signal generated from said data pattern on one another to provide said comparison of the same.

Claim 7

Apparatus for use in conjunction with a predetermined data pattern applied to a data storage surface in reporting the location of a data transfer device with respect to a desired positioning thereof relative to said data storage surface, comprising means responsive to a reading by said data transfer device of said data pattern by generating therefrom a signal having at least a pair of states whose relationship to one another is indicative of the location of said data transfer device with respect to said desired positioning, and comparison means for receiving said pair of signal states and comparing the same to provide an output reporting said location of said data transfer device with respect to said desired positioning and wherein said desired positioning is the proper position of said transfer device with respect to said surface for transferring data to a predetermined track location thereon, said predetermined data pattern is one applied to said data storage surface on a test track which is superimposed spacially along said track location, and said means for generating a signal in response to a reading by said transfer device of said data pattern generates such a signal having a cyclical waveform whose amplitude at any given time is a function of the location of said transfer device relative to said data pattern on said test track and hence relative to said desired track positioning wherein said data storage surface is mounted for rotation for the reading therefrom during its rotation of data thereon by said data transfer device; said test track having said predetermined data is generally circular and eccentric with respect to the axis of rotation of said surface with said pattern being comprised of a pair of concentric but separated data signals applied on said test track with different frequencies, the summation of such data signals upon simultaneous reading thereof by said data transfer device during rotation of said surface providing a combined carrier signal whose envelope defines for each revolution of said surface with respect to said head of a pair of closed curves meeting at a junction point determined by the beat frequency null of said combined signal and the location of which on a time scalE is representative of the location of said data transfer device with respect to the desired track positioning, and said comparison means includes means for deriving from each of said closed curve envelopes signals representative of the same and means for superimposing one of said signals on another to provide said comparison.

Claim 8

Apparatus for use in conjunction with a predetermined data pattern applied to a data storage surface in reporting the location of a data transfer device with respect to a desired positioning thereof relative to said data storage surface, comprising means responsive to a reading by said data transfer device of said data pattern by generating therefrom a signal having at least a pair of states whose relationship to one another is indicative of the location of said data transfer device with respect to said desired positioning, and comparison means for receiving said pair of signal states and comparing the same to provide an output reporting said location of said data transfer device with respect to said desired positioning and wherein said desired positioning is the proper position of said transfer device with respect to said surface for transferring data to a predetermined track location thereon, said predetermined data pattern is one applied to said data storage surface on a test track which is superimposed spacially along said track location, and said means for generating a signal in response to a reading by said transfer device of said data pattern generates such a signal having a cyclical waveform whose amplitude at any given time is a function of the location of said transfer device relative to said data pattern on said test track and hence relative to said desired track positioning wherein said data storage surface is mounted for rotation for the reading therefrom during its rotation of data thereon by said data transfer device; said test track having said predetermined data is generally circular and eccentric with respect to the axis of rotation of said surface with said pattern being comprised of a pair of concentric but separated data signals applied on said test track with different frequencies, the summation of such data signals upon simultaneous reading thereof by said data transfer device during rotation of said surface providing a combined carrier signal whose envelope defines for each revolution of said surface with respect to said head of a pair of closed curves meeting at a junction point determined by the beat frequency null of said combined signal and the location of which on a time scalE is representative of the location of said data transfer device with respect to the desired track positioning, and said comparison means includes means for deriving from each of said closed curve envelopes signals representative of the same and means for superimposing one of said signals on another to provide said comparison.

Claim 9

The apparatus of claim 5 for reporting the location of a data transfer device with respect to a desired positioning thereof wherein said means for deriving from each of said closed curves a signal representative thereof includes means for detecting the envelope of either the positive or negative portion of said combined signal to provide a recitified signal therefrom having an abruptly changing slope at said null points and for separing said envelope portion from the carrier frequencies thereof, and means for differentiating said rectified signal to provide a signal amplifying said abrupt change of slope.

Claim 10

The apparatus of claim 6 for reporting the location of a data transfer device with respect to a desired positioning thereof wherein said output provided by said comparison means is a visual display output on a cathode ray tube face, and means are included for synchronizing the sweep of said cathode ray tube with each abrupt change in the slope of said signal to thereby superimpose on said cathode ray tube face those portions of said signal representative of adjacent ones of said envelope signal.

Claim 11

The apparatus of claim 7 for reporting the location of a data transfer device with respect to a desired positioning thereof wherein said means for synchronizing the sweep of said cathode ray tube with each abrupt change in the slope of said signal includes counting means responsive to receipt of a predetermined number of abrupt changes in slope by providing a triggering signal which is usable to trigger the sweeping of said cathode ray tube.