Read-write servo track copy system

Claim 1

In combination with a read head means adapted to sense discrete relatively short designations in a magnetized track wherein the track is magnetized in a first direction and the designations are magnetized in a second direction, said read head means providing for each designation a signal with an amplitude which first varies from a zero reference level in a first direction, toward a first peak, thereafter crosses said zero reference level and then varies from the zero reference level in a second direction toward a second peak and returns to said zero reference level to thereby form said first and second peaks of opposite polarities, with respect to said zero reference level, the combination comprising: a zero crossing detector for providing a first pulse when the amplitude of said signal first varies from said zero reference level in said first direction and a second pulse when said signal amplitude crosses said zero reference level and varies in said second direction; first means for establishing a time interval which extends from the time when the amplitude of said signal first equals a first reference amplitude which is between said zero reference level and said first peak to the time when the amplitude of said first signals equals a second reference amplitude, which is between said zero reference level and said second peak, said first and second reference amplitudes having opposite polarities with respect to said zero reference level; gating means coupled to said zero crossing detector and to said first means, said gating means being enabled only during said time interval for providing a first control pulse only in response to said second pulse from said zero crossing detector with said gating means being inhibited from providing a pulse corresponding to said first pulse; delay means responsive to said first control pulse for providing a second control pulse delayed by a fixed time period from said first control pulse; and utilization means for utilizing said first and second control pulses.

Claim 8

A method of transcribing a magnetized track which is magnetized in a first direction except for discrete relatively short designations which are magnetized in a second direction, the steps comprising: sensing the directions of magnetization in said track by providing for each discrete designation a signal whose amplitude first varies from a zero reference level in a first direction toward a first peak, thereafter changes and crosses said zero reference level and then varies therefrom in a second direction toward a second peak, and thereafter returns to said zero reference level; generating a pulse each time the signal amplitude changes from said zero reference level, whereby for each signal first and second pulses are generated; defining a time interval which extends from the time the signal equals a first reference level which has a first polarity with respect to said zero reference level until the time said signal amplitude equals a second reference level which has a second polarity with respect to said zero reference level, with only said second pulse being generated during said time interval; supplying said first and second pulses to a gating circuit which is enabled only during said time interval, whereby only said second pulse passes through said gating circuit to define a first control pulse; generating in response to said first control pulse a second control pulse which is delayed a preselected period from said first control pulse; providing current from a source to a magnetic write head; controlling the current in said write head to flow in a first direction during the duration between said first and second control pulses, and controlling the current to flow in a second direction following said second control pulse; and moving a magnetizable track past said write head to control the magnetization of said track to be in a first direction or a second direction when the current in the write head flows in the first direction or the second direction, respectively.

Claim 9

A method of transcribing a magnetized track which is magnetized in a first direction except for discrete relatively short designations which are magnetized in a second direction, the steps comprising: sensing the directions of magnetization in said track by providing for each discrete designation a signal whose amplitude first varies from a zero reference level in a first direction toward a first peak, thereafter changes and crosses said zero reference level and then varies therefrom in a second direction toward a second peak, and thereafter returns to said zero reference level; generating a pulse each time the signal amplitude changes from said zero reference level, whereby for each signal first and second pulses are generated; defining a time interval which extends from the time the signal equals a first reference level which has a first polarity with respect to said zero reference level until the time said signal amplitude equals a second reference level which has a second polarity with respect to said zero reference level, with only said second pulse being generated during said time interval; supplying said first and second pulses to a gating circuit which is enabled only during said time interval, whereby only said second pulse passes through said gating circuit to define a first control pulse; generating in response to said first control pulse a second control pulse which is delayed a preselected period from said first control pulse; providing current from a source to a magnetic write head; controlling the current in said write head to flow in a first direction during the duration between said first and second control pulses, and controlling the current to flow in a second direction following said second control pulse; and moving a magnetizable track past said write head to control the magnetization of said track to be in a first direction or a second direction when the current in the write head flows in the first direction or the second direction, respectively.