| Patent Number |
Title Of Patent |
Date Issued |
| 7408495 |
Digital equalization of multiple interleaved analog-to-digital converters |
August 5, 2008 |
| Time variant interleaving equalization of an interleaved analog to digital converter is disclosed. A high-frequency analog input signal is converted into a plurality of individual digital signals using a plurality of interleaved analog-to-digital converters. the plurality of individual |
| 7382304 |
Sampling and measurement of periodic signals |
June 3, 2008 |
| A periodic signal is sampled. The sampling frequency is less than the Nyquist rate of the periodic signal. A period of the periodic signal is determined. A phase of the periodic signal is tracked to determine a sample's position on the period of the periodic signal. A replica of the |
| 7295002 |
Vacuum chuck spinstand for testing magnetic heads and disks |
November 13, 2007 |
| A spinstand having a vacuum chuck clamping mechanism for securing magnetic discs includes a cap (9) and a base (10). A disk-to-be-clamped is held between the cap (9) and the base (10). Vacuum, applied through a port (4) in a mounting screw (12) of the base, provides the clamping force. T |
| 7245449 |
Timing analysis of read back signals in magnetic recording devices |
July 17, 2007 |
| Analysis of a read back signal in a magnetic recording device is disclosed. The read back signal is converted to a digital read back signal, and a low frequency component of the digital read back signal is restored. A sample clock is recovered from the restored digital read back sign |
| 7240777 |
Constrained layer damping assembly |
July 10, 2007 |
| A constrained layer damping assembly for a rigid base member having a substantially planar surface comprises a gas impervious damping layer disposed on the substantially planar surface of the base member, and a load element disposed on the damping layer. The damping layer defines at |
| 7221220 |
Method and apparatus for low-frequency bypass in broadband RF circuitry |
May 22, 2007 |
| A method of processing an input broadband signal in RF circuitry includes extracting low-frequency components from the input broadband signal, processing the low-frequency components in low-frequency bypass circuitry, and adding the processed low-frequency components to the output of |
| 7165211 |
Viterbi decoder with direct current restoration |
January 16, 2007 |
| A decoder for detecting data within an input signal with attenuated low frequency components that comprises a Viterbi decoder, is disclosed. Viterbi decoder internal data is used along with its output bits to reduce delay between the restored direct current (DC) component and the inp |
| 7158324 |
Self-adjusting PRML receiver |
January 2, 2007 |
| A partial response maximum likelihood (PRML) data detecting in a magnetic recording storage device is carried out with a preliminary measuring of write-read channel responses to all nonzero binary combinations of a given length. Decoding of the user data is performed according to a V |
| 7151393 |
High-speed write driver |
December 19, 2006 |
| A write driver includes two field-effect/bipolar transistors with feedbacks between the drains/collectors and gates/bases, a write/read switch connected between the drains/collectors and a positive power supply, an impedance matching circuit connected to the drains/collectors to matc |
| 7141969 |
X-Y spinstand platform with flexure-coupled platen |
November 28, 2006 |
| An XY platen positioning system includes a fixed base rigidly coupled to a essentially planar surface. An XY intermediate plate is slidably coupled to the fixed base, such that the XY intermediate plate is slidable in the X axis along the fixed base. An XY stage is slidably coupled to th |
| 7124043 |
Spectrum analyzer with phase noise compensation |
October 17, 2006 |
| A spectrum analyzer with a compensation circuitry for prevention of measurement accuracy deterioration due to local oscillators phase noise. |
| 7061321 |
Low impedance read amplifier for magnetoresistive head |
June 13, 2006 |
| A read amplifier system for connection through interconnects to a magnetoresistive (MR) head includes two input transistors, two bias transistors connected to the two input transistors by common source connections, a bias voltage control circuit connected to base terminals of the two |
| 7061235 |
Magnetic head and disk X-Y test assembly with optimized arrangement for skew angle |
June 13, 2006 |
| A magnetic head and disk tester comprises a base, a spindle for rotationally supporting a magnetic disk, a carriage for supporting a magnetic head support which carries a magnetic head with a magnetic read/write element, and a dual-stage positioning system that moves the carriage in |
| 6785085 |
Multi-frequency servo bursts in magnetic disc memory system |
August 31, 2004 |
| A servo burst pattern for use in positioning a read/write head with respect to tracks on a magnetic disc medium includes a first set of servo bursts adjacently disposed on the tracks along a first axis perpendicular to the centerlines. Each of the first set of bursts is disposed on an in |
| 6772079 |
Method and apparatus for equalization of a signal acquisition system |
August 3, 2004 |
| In a signal acquisition system in accordance with the principles of the present invention, a digital signal acquisition system includes a front end, an equalizer and an output system. The front end typically includes an input amplifier and may include one or more preamplifiers, and any o |
| 6760171 |
Magnetic medium precompensation method and apparatus |
July 6, 2004 |
| A magnetic medium write precompensation circuit produces a precisely controlled delay for magnetic medium write precompensation by digital-to-analog converting a data value, low-pass filtering the digital-to-analog converted signal, and limiting the filtered signal to produce a desir |
| 6661607 |
Method and apparatus for electromagnetic interference reduction in magnetic recording devices |
December 9, 2003 |
| In a magnetic recording/reproduction device, such as a disk drive one or more conductive elements is positioned in close proximity to a recording/reproduction head in order to absorb EMI generated by the head as it reads and/or writes data from/to magnetic media. The conductive eleme |
| 6469862 |
Method and apparatus for improved servo signal filtering in read channels |
October 22, 2002 |
| A read channel network of a magnetic data storage device receives analog signals representative of user data and servo data, wherein the servo data is usable to position a read/write magnetic head. The servo data is separately processed within the read channel network to improve the sign |
| 6242910 |
Magnetic head and disk tester with yaw correction |
June 5, 2001 |
| A magnetic head and disk tester includes a magnetic head which is selectively positioned relative to a rotatably mounted magnetic disk to accomplish testing of either of the head or disk or both. The magnetic head is secured to a carriage which is under electro-mechanical control, wh |
| 6236201 |
Magnetic head and disk tester with pitch correction |
May 22, 2001 |
| A magnetic head and disk tester provides accurate positioning of a magnetic read-write head over a magnetic disk by means of a coarse positioning mechanism and a fine positioning mechanism. The coarse positioning mechanism includes a stepper motor, a lead screw, a nut, rear sliders and |
| 6229304 |
Apparatus for air flow stabilization in spinstands with a shroud assembly and a shell assembly |
May 8, 2001 |
| A shroud of suitable shape is provided about the spindle and disk(s) of a spinstand. In some forms, a shell is disposed between the disk locus and the shroud. The shroud (and/or shell) operates to reduce or eliminate air flow at the top and bottom surfaces of the disk(s) and limits the a |
| 6229303 |
Spinstand for testing magnetic heads and disks |
May 8, 2001 |
| A shroud of suitable shape is provided about the spindle and disk(s) of a spinstand. The shroud operates to reduce or eliminate air flow at the top and bottom surfaces of the disk(s) and limits the air volume moved by the rotating disk(s). The shroud also directs the air in a circular pa |
| 6219683 |
Radially distributed transverse filter |
April 17, 2001 |
| A radially distributed transverse filter includes a plurality of delay lines of substantially equal electric length sequentially coupled at a like plurality of nodes. The nodes are distributed equidistant from a common position, for example positioned at vertices of a polygon. A plur |
| 6219194 |
MR head read amplifier with improved write to read recovery time |
April 17, 2001 |
| An apparatus for substantially eliminating a switching voltage transient in a magnetic recording system so as to minimize a write-to-read recovery time includes a first bias enable switch, a bias current source responsive to the first bias enable switch, an MR sensor for receiving a bias |
| 6212045 |
Method and apparatus for loading a magnetic head onto a magnetic disk |
April 3, 2001 |
| A spinstand head-loading mechanism of a magnetic tester includes a protector bar and a lift arm which control the loading and unloading operations of a magnetic head, as part of a head-gimbal assembly, with respect to a magnetic disk. A series of actuators control the engagement and |
| 6094047 |
Method and apparatus for balancing rotating components of a spinstand of a magnetic head and dis |
July 25, 2000 |
| An apparatus for balancing the spinstand of a magnetic head and disk testing system includes a base that rotationally supports a rotating spindle. The spindle supports a pack of disks and a slide moveable along guide rails of the spinstand. The slide, in turn, supports a stack of mag |
| 6064261 |
Write amplifier with improved switching performance, output common-mode voltage, and head curren |
May 16, 2000 |
| A write amplifier is provided with one or more improved switching performance, low output common-mode voltage, and precise write head current control. A low output common-mode voltage is achieved using a combination of circuit components which limit the undesirable delivery of curren |
| 6023145 |
Head and disk tester with a thermal drift-compensated closed-loop positioning system |
February 8, 2000 |
| The head/disk tester of the invention has a housing 43 that houses spindle 44 that rotatingly supports a magnetic disk 31. The housing supports a moveable carriage 30 that, in turn, supports a magnetic head 32. Positioning means 39 and 41 are used to move the carriage and the magnetic |
| 6006614 |
Apparatus and method for improving dynamic characteristics of a fine-positioning mechanism in a |
December 28, 1999 |
| An improved fine positioning mechanism in a magnetic head/disk tester includes a primary position actuator and a primary body that supports a read/write head to be tested, and an auxiliary body and auxiliary actuator. Both actuators operate contemporaneously and in mutually opposite |
| 5932887 |
Apparatus for measuring the flying height and orientation of a magnetic head relative to a trans |
August 3, 1999 |
| The invention provides an apparatus for measuring the flying height and orientation of a magnetic head (54) relative to a transparent disk (20) based on both frustrated total internal reflection and total internal reflection. The apparatus comprises a housing (10) that mounts an electric |
| 5872451 |
System for locating and fixing a headstack assembly on headstack tester |
February 16, 1999 |
| A method and a system for fixing and positioning a headstack (100, 200, 300, 400) on a headstack tester by utilizing a vacuum chuck (105, 106, 208, 310). The vacuum chuck engages headstack. This engagement determines the exact position of the magnetic heads (24a, 24b . . . ) supported by |
| 5825180 |
Magnetic disk test apparatus having heads moveable along substantially parallel axes |
October 20, 1998 |
| An apparatus for testing and processing a magnetic disk. The apparatus comprises a spindle for rotatably supporting the disk about a spindle axis; a first read and/or write head; a second read and/or write head; a gliding head; and a burnishing head, where the heads are selectively p |
| 5789756 |
Apparatus for measuring the flying height and orientation of a magnetic head relative to transpa |
August 4, 1998 |
| The invention provides an apparatus for measuring the flying height and orientation of a magnetic head (54) relative to a transparent disk (20) based on frustrated total internal reflection. The apparatus comprises a housing (10) that mounts an electric motor (12) which rotationally |
| 5677805 |
Apparatus for determining the dynamic position and orientation of a transducing head relative to |
October 14, 1997 |
| An apparatus for determining the position and/or orientation of a transducing head positioned on one side of and close to a rotating transparent-core magnetic storage disk. Light is introduced into the disk to establish total internal reflection therein. A detector disposed on the ot |
| 4710686 |
Method and apparatus for control of current in a motor winding |
December 1, 1987 |
| A current driver circuit for an inductive load, such as a motor winding, provides unidirectional, controlled current through the winding by use of two pulse width modulator switches on opposite sides of the winding or bidirectional current control by use of two pairs of pulse width modul |
| 4680516 |
Motor speed control system |
July 14, 1987 |
| A motor speed control system comprises an encoder (12) which produces a series of indicator pulses related to the motor's speed. The period of the pulse is compared with that of a crystal-controlled reference period produced by a period generator (14). Comparison is made by means of a |
| 4627288 |
Bearing unloading mechanism for disc clamping unit |
December 9, 1986 |
| A bearing unloading mechanism for a disc clamping unit utilized in rigid disc certifiers or testers comprises a hollow spindle (12) containing a pulling rod (20) which slides in the spindle. The upper end of the pulling rod carries a clamping element (26) for clamping a disc (D) to be te |
