Magnetic data reading apparatus and method using inductive and magnetoresistive heads
AssigneeInternational Business Machines Corporation
InventorsEarl Albert Cunningham, Jodie Ann Christner
Life of this patent
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Abstract
A rigid disk drive unit includes head assemblies having both inductive and magnetoresistive heads. When information is read from a disk surface, signals from the inductive head and the magnetoresistive head are combined to provide an output signal, thereby to overcome disadvantages of using either signal alone. The relative contributions of the magnetoresistive and inductive signals are varied to optimize performance depending on the radial position of the head assembly over a magnetic disk and upon whether the information being read is data or servo position information. The inductive signal is ignored during data recovery procedure head shift operations.
Claims19
A data storage device comprising in combination:
- housing means;
- a magnetic data storage medium including an information storage region contained in said housing means;
- a magnetically recorded stream of information on said information storage region;
- a transducer head assembly contained in said housing means;
- actuator means connected to said transducer head assembly for moving said transducer head assembly relative to said data storage medium;
- control means connected to said actuator means for locating said transducer head assembly in registration with said information storage region;
- said transducer head assembly including a magnetoresistive head and an electromagnetic head;
- said magnetoresistive head and said electromagnetic head being superimposed for simultaneous registration with said information stream;
- and a preamplifier connected to said transducer head assembly for processing signals read from said information storage region;
- said data storage device being characterized by:
- said preamplifier including signal processing means for providing an output signal by simultaneously processing signals read by both said magnetoresistive head and said electromagnetic head;
- said signal processing means including a first amplifier means connected to said magnetoresistive head and second amplifier means connected to said electromagnetic head, and adjustable gain control means for independently setting the gains of said first and second amplifier means to vary the relative contribution of said magnetoresistive and inductive heads to said output signal.
Apparatus for reading data information and servo information from tracks of a magnetic surface of a rotating magnetic data storage disk, said apparatus comprising:
- an integrated head assembly including a magnetoresistive head and a superimposed electromagnetic head;
- amplifier means for simultaneously processing signals from said magnetoresistive head and electromagnetic head;
- said amplifier means including a first stage having an input connected to said magnetoresistive head and having an output, a second stage parallel to said first stage having an input connected to said electromagnetic head and having an output, and a third stage having an input connected to receive a combined signal from said outputs of first and second stages;
- and
- gain control means for adjusting the gain of said first and second stages independently of one another to vary the relative contribution of said magnetoresistive and inductive heads to said combined signal.
A method for reading from a magnetic medium having a storage region including a stream of recorded information, said method comprising:
- positioning a magnetoresistive head in registration with the storage region;
- superimposing an electromagnetic head with the magnetoresistive head in registration with the storage region;
- simultaneously reading the information stream with both the magnetoresistive head and the electromagnetic head;
- providing an output signal by combining the signals from both the magnetoresistive head and the electromagnetic head;
- and
- preamplifying the signals from both the magnetoresistive head and the electromagnetic head before said combining step;
- said preamplifying step including adjusting the relative contribution of said signals from the magnetoresistive head and the electromagnetic head depending on the radial position of the transducer head assembly on the disk.
A method for reading from a magnetic medium having a storage region including a stream of recorded information, said method comprising:
- positioning a magnetoresistive head in registration with the storage region;
- superimposing an electromagnetic head with the magnetoresistive head in registration with the storage region;
- simultaneously reading the information stream with both the magnetoresistive head and the electromagnetic head;
- providing an output signal by combining the signals from both the magnetoresistive head and the electromagnetic head;
- and
- preamplifying the signals from both the magnetoresistive head and the electromagnetic head before said combining step;
- said preamplifying step including disabling the signal from the electromagnetic head during a head shift data recovery procedure.
A method for reading from a magnetic medium having a storage region including a stream of recorded information, said method comprising:
- positioning a magnetoresistive head in registration with the storage region;
- superimposing an electromagnetic head with the magnetoresistive head in registration with the storage region;
- simultaneously reading the information stream with both the magnetoresistive head and the electromagnetic head;
- providing an output signal by combining the signals from both the magnetoresistive head and the electromagnetic head;
- and
- preamplifying the signals from both the magnetoresistive head and the electromagnetic head before said combining step;
- said preamplifying step including detecting whether the information stream being read is data or servo, and adjusting the relative contribution of said signals from the magnetoresistive head and the electromagnetic head depending on whether the information stream being read is data or servo.
Dependencies are inferred from the claim text.