Magnetic recording system with peak shift compensation

• US 4,553,178 A
• Filed: 01/18/1983
• Issued: 11/12/1985
• Est. Priority Date: 01/18/1983
• Status: Expired due to Fees

• Current Assignee: Electronic Processors, Inc.
• Original Assignee: Electronic Processors, Inc.
• Inventors: Lynch, Donald F.
• Primary Examiner(s): Canney, Vincent P.
• Application Number:
  US06/458,965
• Time in Patent Office: 1,029 Days
• Field of Search: 360/45, 360/46, 360/68
• US Class Current: 360/45
• CPC Class Codes: G11B 20/10212 compensation for data shift, e.g. pulse-crowding effects

Abstract

A method and system provide for the compensation of peak shift of digital data recorded on D.C. premagnetized (erased) magnetic media. D.C. erasure results in the entire magnetic medium being aligned (polarized) in a single direction. The subsequent magnetic recording of data on such premagnetized medium normally results in a peak shift whenever the subsequently recorded signal traverses in the same direction of polarization as the single polarized direction of the D.C. erased medium. Such peak shift is compensated for in the present invention by utilization of a compensation circuit which, upon the receipt of an encoding signal which would cause data to be recorded which would traverse (be polarized) in the same direction as the premagnetized medium, is activated to provide a modified encoding signal to vary the placement of the magnetic boundaries of the recorded signal to compensate for its anticipated peak shift. The compensating circuit of the present invention is intermediate the source of the data encoding signal and the magnetic write head transducer. The compensating circuit of the present invention may either delay the return transition of the magnetically recorded signal, or cause the switching transition to be written earlier.

Claims

1. A system for writing digital data on magnetic recording medium which is D.C. premagnetized in a substantially single polarized direction, which system compensates to avoid peak shift during read-out due to the subsequent magnetic recording of data on said medium which magnetic data traverses said medium in substantially the said polarized direction as the polarized direction of D.C. premagnetization, said system including:

a magnetic write head transducer for selectively applying magnetic data to D.C. premagnetized magnetic recording medium in a polarized direction which traverses such medium in substantially the same direction and its D.C. premagnetized polarized direction and in at least one other direction;

means for providing digital data encoding signals for activating said magnetic transducer to selectively apply polarized magnetic data to D.C. premagnetized magnetic recording medium in subsantially the same direction as the direction of D.C. premagnetization and in at least one other direction; and

means for adjusting the timing of the digital data encoding signal means when its activating signal is of the kind which would activate said magnetic transducer to apply magnetic data to D.C. premagnetized magnetic recording medium in substantially the same direction of polarization as the direction of the polarized D.C. premagnetization of said medium, wherein said timing adjusting means includes a resistor, a capacitor, and a first and second inverter, said resistor and said capacitor being in parallel with one another, said resistor and capacitor also both being in series with said signal encoding means, and wherein said first inverter is located in series between said signal encoding means and said resistor and capacitor and said second inverter is located in series after said resistor and capacitor;

whereby peak shift due to the recording of data which traverses D.C. premagnetized magnetic medium in substantially the same polarized direction as the polarized direction of D.C. premagnetization of said medium is compensated to avoid shift in the read-out of data recorded on said D.C. premagnetized magnetic medium.

2. The system of claim 1 wherein said first inverter is an open collector having low impedance.

3. A system for writing digital data on magnetic recording medium which is D.C. premagnetized in a substantially single polarized direction, which system compensates to avoid peak shift during read-out due to the subsequent magnetic recording of data on said medium which magnetic data traverses said medium in substantially the same polarized direction as the polarized direction of D.C. premagnetization, said system including:

a magnetic write head transducer for selectively applying magnetic data to D.C. premagnetized magnetic recording medium in a polarized direction which traverses such medium in substantially the same direction and its D.C. premagnetized polarized direction and in at least one other direction;

means for providing digital data encoding signals for activating said magnetic transducer to selectively apply polarized magnetic data to D.C. premagnetized magnetic recording medium in substantially the same direction as the direction of D.C. premagnetization and in at least one other direction; and

means for adjusting the timing of the digital data encoding signal means when its activating signal is of the kind which would activate said magnetic transducer to apply magnetic data to D.C. premagnetized magnetic recording medium in substantially the same direction of polarization as the direction of the polarized D.C. premagnetization of said medium, wherein said timing adjusting means includes a delay line and a "D" type flip-flop, said delay line being in series between said signal encoding means and said flip-flop, and with said flip-flop also being in shunted direct series contact with said signal encoding means, said flip-flop arranged for activation in response to a signal which would activate said magnetic transducer to apply magnetic data to D.C. premagnetized magnetic recording medium in substantially the same direction of polarization as the direction of polarized D.C. premagnetization of the medium;

whereby peak shift due to the recording of data which traverses D.C. premagnetized magnetic medium in substantially the same polarized direction as the polarized direction of D.C. premagnetization of said medium is compensated to avoid shift in the read-out of data recorded on said D.C. premagnetized magnesium medium.

4. A system for writing digital data on magnetic recording medium which is D.C. premagnetized in a substantially single polarized direction, which system compensates to avoid peak shift during read-out due to the subsequent magnetic recording of data on said medium which magnetic data traverses said medium in substantially the same polarized direction as the polarized direction of D.C. premagnetization, said system including:

a magnetic write head transducer for selectively applying magnetic data to D.C. premagnetized magnetic recording medium in a polarized direction which traverses such medium in substantially the same direction and its D.C. premagnetized polarized direction and in at least one other direction;

means for providing digital data encoding signals for activating said magnetic transducer to selectively apply polarized magnetic data to D.C. premagnetized magnetic recording medium in substantially the same direction as the direction of D.C. premagnetization and in at least one other direction; and

means for adjusting the timing of the digital data encoding signal means when its activating signal is of the kind which would activate said magnetic transducer to apply magnetic data to D.C. premagnetized magnetic recording medium in substantially the same direction of polarization as the direction of the polarized D.C. premagnetization of said medium, wherein said timing adjusting means includes a capacitor, said capacitor being in series with said signal encoding means, said capacitor located and selected for activation in response to a signal which would activate said magnetic transducer to apply magnetic data to D.C. premagnetized magnetic recording medium in substantially the same direction of polarization as the direction of the polarized D.C. premagnetization of the medium;

whereby peak shift due to the recording of data which traverses D.C. premagnetized magnetic medium in substantially the same polarized direction as the polarized direction of D.C. premagnetization of said medium is compensated to avoid shift in the read-out of data recorded on said D.C. premagnetized magnetic medium.