MAGNETIC DATA READING APPARATUS AND METHOD USING INDUCTIVE AND MAGNETORESISTIVE HEAD

A RIGID DISK DRIVE UNIT (12) INCLUDES HEAD ASSEMBLIES (28) HAVING BOTH INDUCTIVE AND MAGNETORESISTIVE HEADS (44, 46). WHEN INFORMATION IS READ FROM A DISK SURFACE (20), SIGNALS FROM THE INDUCTIVE HEAD (44) AND THE MAGNETO-RESISTIVE HEAD (46) 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 (18) AND UPON WHETHER THE INFORMATION BEING READ IS DATA (24A) OR SERVO POSITION INFORMATION (24B). THE INDUCTIVE SIGNAL IS IGNORED DURING DATA RECOVERY PROCEDURE HEAD SHIFT OPERATIONS (136). (FIG. 6)