Patents Examined by Dau I. Davidson
-
Patent number: 6476997Abstract: A disk device, track positioning method, and method for generating a position error signal in which the occurrence of a wrong correction operation can be prevented by creating an appropriate PES without using a burst pattern having a defect, and reassign sectors can be decreased by decreasing defective sectors thereby to reduce the performance degradation is disclosed. In the disk device and track positioning method, the defect of a burst pattern read out from a disk is detected, and if a defect is detected in the burst pattern, a data value corresponding to the sum data of the burst pattern pair having the defect detected is obtained by measuring the maximum amplitude value of the burst pattern pairing with the burst pattern having the defect detected, and a PES is created according to the amplitude of the burst pattern having the defect detected and the maximum amplitude value.Type: GrantFiled: July 22, 1998Date of Patent: November 5, 2002Assignee: International Business Machines CorporationInventors: Yukio Fukushima, Tetsuo Ueda, Toshio Kakihara, Hideo Asano
-
Patent number: 6396653Abstract: An apparatus and method for minimizing audible noise in disc drives during idle periods uses a low-noise velocity profile and/or low noise position profile to govern the movement of a seeking actuator assembly. The low-noise velocity profile is selected to govern all actuator movement and seeking during idle periods, i.e., during internal drive housekeeping operations. The noise level associated with each actuator position in the drive is preferably determined through actual tests and/or modeling and is utilized to determine the low noise profiles. The relative amount of time the actuator assembly spends in the relatively noisier actuator assembly positions may also be optimally reduced thus reducing the overall amount of noise generated by an idle disc drive.Type: GrantFiled: March 27, 2000Date of Patent: May 28, 2002Assignee: Seagate Technology LLCInventors: Jonathan Williams Haines, Frank William Bernett
-
Patent number: 6275347Abstract: A read system for reading information from a storage medium and for providing an output signal to circuitry external from the read system is disclosed. The read system includes individual channel circuitry, a bias current generator for providing a bias current to the read system, and preamplifier circuitry connected between the bias current generator and the individual channel circuitry. The individual channel circuitry further includes a first and a second magnetoresistive element, a first and a second transistor, and a first and a second switch. The preamplifier circuit further includes a first and a second capacitor connected between a low potential and the first and second switches, respectively, and a third capacitor connected between the first and second capacitors. The preamplifier also includes a first and a second operational amplifier having an output connected to a base of the first transistor and a base of the second transistor.Type: GrantFiled: April 2, 1999Date of Patent: August 14, 2001Assignee: Agere Systems Guardian Corp.Inventors: Tuan V. Ngo, John D. Leighton
-
Patent number: 6268974Abstract: Apparatus and method for selecting an optimum gain for an amplifier used to amplify readback signals transduced from a magnetic recording disc in a disc drive. The amplifier is provided with a first value of gain, which is used to amplify a readback signal to generate an amplified readback signal. The amplified readback signal is in turn applied to an automatic gain control circuit comprising a variable gain amplifier. The variable gain amplifier applies a variable gain from a selected range to the amplified readback signal to maintain an amplitude of an output signal provided by the automatic gain control circuit at a nominal amplitude. The acceptability of the first value of gain for subsequent use by the amplifier is determined in relation to a magnitude of the variable gain applied by the variable gain amplifier.Type: GrantFiled: July 13, 1999Date of Patent: July 31, 2001Assignee: Seagate Technology LLCInventors: Brett A. Sloan, Paul F. Kusbel, John E. Moon, Tim Walker
-
Patent number: 6122135Abstract: A method to adaptively reduce error introduced by the coil current rise time. A disk drive with a moving arm actuator driven by a voice coil motor is controlled by periodically modeling the coil current rise time. An adjustment to a commanded current value is based on the model of the coil current rise time and a magnitude change in commanded value. The model of the coil current is based on a linear approximation to the exponential rise time of the coil current. The commanded value is adjusted to compensate for the error in the control effort. For small commanded value differences no compensation is made for the coil current rise time. For medium command value differences a slope intercept equation is used to compute the compensated commanded value. For large commanded value differences half of an estimate of the maximum largest physical current change is used. The adjustment is made by the estimator in a position error signal feedback control system.Type: GrantFiled: December 19, 1997Date of Patent: September 19, 2000Assignee: Western Digital CorporationInventor: Michael Charles Stich