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Twin Track Magnetic Read/Write Head

IP.com Disclosure Number: IPCOM000046271D
Original Publication Date: 1983-Jun-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 4 page(s) / 80K

Publishing Venue

IBM

Related People

Vinal, AW: AUTHOR

Abstract

Fig. 1 illustrates a plan view of a typical silicon semiconductor substrate having deposited on or diffused into its surface a variety of elements for forming a magnetic twin track reading and writing head structure. An alternate structure technique utilizing a ceramic substrate for the writing head and a silicon substrate for the read head, which are later sandwiched together, is also shown. The read head portion utilizes a magnetically sensitive transistor located in the back gap between two magnetically permeable legs that couple flux from a magnetic medium adjacent to a surface of the read/write head to the active area of the magnetic transistor.

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Twin Track Magnetic Read/Write Head

Fig. 1 illustrates a plan view of a typical silicon semiconductor substrate having deposited on or diffused into its surface a variety of elements for forming a magnetic twin track reading and writing head structure. An alternate structure technique utilizing a ceramic substrate for the writing head and a silicon substrate for the read head, which are later sandwiched together, is also shown. The read head portion utilizes a magnetically sensitive transistor located in the back gap between two magnetically permeable legs that couple flux from a magnetic medium adjacent to a surface of the read/write head to the active area of the magnetic transistor.

The twin track read head is integrated in Fig. 1 with a twin track writing head. Twin data tracks may be very narrow, and the design described makes possible the simultaneous alignment of the write and read portions of the head during manufacture. The magnetic transistor comprising an emitter 2 implanted or diffused on the surface of substrate 1 and doped with N-type material is located in the gap G having a typical width which may be as small as 1 micron.

A P+ diffusion surrounds the sides of the emitter 2 to limit injection in Fig. 1 downward into the plane of the substrate. The P+ pocket is shown as 3. Magnetically permeable conductor legs 4 conduct magnetic flux from the surface 5 that would be placed adjacent to a magnetic medium recorded with magnetization reversals, as will be described later. Collectors 6 are diffused into substrate 1 and are doped with N-type material. A base contact 7 is also supplied. A differential output will be developed between the collectors 6 in the presence of magnetic flux field passing across the plane of the emissive surface of emitter 2. The field crossing the gap G reaches a maximum value when the ends of the legs 4, which are nearest the magnetic medium (not shown), lie directly over discontinuities in the magnetization vector. By writing data tracks in opposite polarity, and utilizing two adjacent tracks for writing, the flux magnitude may be greatly increased. The magnetic transistor will develop a signal that produces a differential output at the collectors with polarity and amplitudes proportional to the field direction and magnitude that crosses the gap G.

Data is written along the length of a storage medium (not shown) in either the lateral or vertical recording mode depending upon the direction of anisotropy of the magnetic medium in the recording material. Whatever is written in one track, such as the track designated A or B in Fig. 1, is written in the opposite direction in the adjoining track. The reversal in direction is accomplished by the magnetizing coils 8, which are connected in series opposition when a write current Iw is applied at terminals 9 and 10. The magnetic flux field in the coils 8 will be reversed due to the relative direction of current flow, starting either at the outside of one c...