International Business Machines Corporation

Hitachi Global Storage Technologies Netherlands B.v.

Mark E Re

Mohamad Towfik Krounbi

Anthony Paul Praino

David William Abraham

Hemantha Kumar Wickramasinghe

Gordon James Smith

Bucknell Chapman Webb

Hal Hjalmar Ottesen

Ferdinand Hendriks

Philip Louis Trouilloud

Shinji Takayama

Bernell E Argyle

Michael A Russak

Rudolf Schafer

A horizontal combined head is provided which has both a thin film write and an MR read element located at an air bearing surface (ABS). The read element can be formed with a track width that is independent of the track width of the write element. The MR sensor or the read element is separated from one of the first and second pole pieces of the write element by an insulation layer. Accordingly, the shields for the read element remain more stable after a write operation. In one embodiment of the present invention a single stripe MR sensor is employed while in a second embodiment a dual stripe MR sensor is employed. A method of the invention includes forming the dual MR stripe in a single process step so that the dual MR stripes of the dual MR sensor are near identical for implementing near absolute common mode rejection of noise.

Method of manufacturing a horizontal thin film write, MR read head

A method of making a magnetic head includes imbedding a coil layer in an insulation stack. The coil layer is formed with a filament that extends about a central axis. The central axis is perpendicular to a planar head surface and a coil plane. First and second pole pieces are formed with the insulation stack sandwiched between the first and second pole pieces. A first shield layer having first and second major planar thin film surfaces is joined by a third edge with the first major planar thin film surface of the first shield layer forming a portion of the planar head surface. A magnetoresistive (MR) sensor and first and second gap layers are formed with the MR sensor sandwiched between the first and second gap layers and the first and second gap layers located between the third edge and the first horizontal component and with the MR sensor and the first and second gap layers forming portions of the planar head surface.

Method of making a magnetic head

Method of making a horizontal thin film write and read head

Method of making horizontal thin film write, MR read head

An apparatus and method for reading an information signal from a magnetic storage medium using a magnetoresistive (MR) head, and separating a thermal signal component and, if present, a magnetic signal component from the information signal. A signal separation/restoration module eliminates distortion in the magnetic signal component of a readback signal induced by a thermal signal component of the readback signal. A finite impulse response (FIR) filter may be employed in the signal separation/restoration module to eliminate the distortion in the magnetic signal. The signal separation/restoration module may be employed to extract the thermal signal component from the readback signal. In one configuration, an MR head is coupled to an arm electronics (AE) module, having a highpass filtering behavior, and a signal separation/restoration module that includes an inverse filter having a transfer function inverse to that of the effective highpass filter of the AE module. The inverse filter may be an infinite impulse response (IIR) filter. In another embodiment, the magnetic and thermal signal components of a readback signal are respectively extracted and processed so as to linearly correspond to head-to-disk spacing. Head-to-disk spacing change using the thermal signal is used to detect disk surface defects, topographic variations, and servo control surface variations.

Method and apparatus for separating magnetic and thermal components from

A method and apparatus for accessing a data storage medium having raised and lowered portions indicative of data stored on the medium. Energy is supplied to a sensor which is moved relative to, and in close proximity to, a surface of the medium on which the data in the form of raised and lowered portions is stored. The sensor and the storage medium are moved in relation thereto, such that the sensor remains at a substantially constant fly spacing therefrom. A decrease in temperature of the sensor is detected when it is in proximity to a variation, i.e., a raised portion on the medium. This detected decrease in temperature associated with a raised variation, e.g., asperity, can be used as the basis upon which to detect the data on the data storage medium. The data storage medium may also contain magnetically stored data, such that the surface variations and the magnetic characteristics of the data storage medium can both be utilized to store data thereon.

Method and apparatus for data storage using thermal proximity imaging

Horizontal thin film write, MR read head

An air bearing slider incorporating the invention has both front and rear pads extending from a generally planar body. Both pads have bearing faces separated by a gap that is substantially in excess of any fly height of the slider. The sides of both pads are oriented at a rake angle that is approximately equal to the maximum expected skew angle. The separation of the pads enables the slider to exhibit good pitch stability, and the pad rake angles provide resistance to roll effects that occur at large skew angles. Both pad faces exhibit extremely small taper angles that enable 'inlet throttling' of air entrained by the slider. Such inlet throttling provides the slider with a fly height that is substantially independent of relative speed changes between the slider and a recording medium. A further embodiment includes a rear slider for contact recording applications.

Speed and skew independent, air bearing slider

A method and apparatus for mapping the character and location of small surface variations on a planar surface. Energy is supplied to an object in close proximity to the planar surface to thereby raise the temperature of the object. The object is moved with respect to the planer surface substantially constant. A decrease in temperature of the object is detected when it is in proximity to the variation to define the location and character of the variation. The energy supply may be thermal energy or optical energy but preferably is electrical energy which heats a resistive element. Preferably, the object is the magnetoresistive head of a disk drive assembly. The surface may be that of a magnetic recording material. The change in temperature is detected by monitoring the resistance of the magnetoresistive coil of the head. The energy may be supplied in pulses to obtain higher peek temperatures while avoiding mechanical distortion of the object. It is preferred that the object be positioned with respect to the surface so that when that relative motion between the surface and the object occurs, the object does not contact the surface.

Method and apparatus for detecting asperities on magnetic disks using

A method and apparatus for conditioning a magnetic read/write head to substantially eliminate read-back pulse distortions associated with unfavorable magnetic domain patterns in the head stores the polarity of the last write current pulse of a write pulse train applied to the head-coils. This polarity is compared to a pre-determined reset current pulse polarity. If the last write current polarity is opposite to the reset current polarity, then a reset pulse, or a series of pulses, having the pre-determined reset polarity is applied to the head prior to performing a read operation with the head. The pre-determined reset polarity corresponds to the polarity that resets the head to the magnetic domain state most preferred for reading due to reduction of read-back distortion. The reset pulse, or pulse train, according to the present invention is of constant polarity. If the last write current pulse polarity is the same as the reset polarity, then no reset pulse is applied to the head. Prior to applying the reset pulse, the head is either re-positioned or, if not re-positioned, the reset pulse is applied to the head only when it is flying over a sector gap.

Electrical means to diminish read-back signal waveform distortion in

A thin film magnetic head, having a predetermined cut-off frequency is constructed of alternating first and second layers, the first layers include a magnetic material and the second layers include a resistive material. The resistivity of the second layers is chosen so that the head's cut-off frequency exceeds the head's required frequency response. The resistivity of the second layers is chosen to be considerably less than any level of resistivity which falls within the insulation regime.

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Los Gatos, CA, United States of America

Mark E Re