Planar Write Module And Hybrid Planar Write-Vertical Read Bidirectional Tape Head
A planar write module and a hybrid planar write-vertical read bidirectional tape head comprising the write module and one or more vertical read modules. The write module has a write module tape bearing surface for engaging the magnetic recording tape. Plural write elements in the write module each comprise plural thin film layers oriented in generally parallel planar relationship with the write module tape bearing surface. The write elements are arranged so that the transducing gaps of adjacent write elements are generally aligned in a direction that is transverse to a streaming direction of the magnetic recording tape. Each read module has a read module tape bearing surface for engaging the magnetic recording tape. Plural read elements in the one or more read modules each comprise plural thin film layers oriented in generally perpendicular relationship with the read module tape bearing surface.
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1. Field of the Invention
This invention relates to tape drive data storage systems. More particularly, the invention is directed to thin film tape heads for reading and writing data on magnetic recording tape.
2. Description of the Prior Art
Thin film tape heads for magnetic information storage systems (e.g., tape drives) have been constructed using the same fabrication techniques used by disk drive manufacturers. A characteristic of such construction is that the thin film layers which comprise the read and write transducer elements are oriented perpendicularly to the tape bearing surface (TBS) of the head. Such heads may be referred to as “vertical” heads due to the fact that the read and write gap portions are situated at the TBS, while the element layer structures extend vertically away from the TBS. In a vertical head with multitrack recording capability, plural transducer elements are commonly arranged side-by-side to form a linear transducer array that is transverse to the direction of tape movement. Each transducer element in the array is positioned to write or read a separate longitudinal track on the tape. This arrangement is shown in
A disadvantage of vertical head constructions as described above is that the transducer element gaps at the TBS must be sufficiently spaced from each other to provide room for the major portion of the transducer element structure that is recessed behind the TBS. For a write element, the recessed structure includes the pole pieces and the coil windings, which (as can be seen in
The comb effect can be solved by stepping the head in a cross-track direction during multiple transducing passes, such that the inter-track white space is ultimately recorded with data after some number of passes have been made. Tape tracks can also be written at less than the gap width of the write transducers using a process known as “shingling.” According to this technique, the head is stepped by less than the write element gap width for each successive transducing pass, such that the edge of a previously written track is overwritten during the next pass, much like shingles on a roof.
Although the foregoing track writing techniques allow data to be densely packed on a tape, a continuing unresolved problem is track misregistration caused by tape dimensional changes between writing and reading operations. For example, a tape may be written with data under one set of temperature and humidity conditions, and then later read following exposure to different environmental conditions. For conventional tape material, the dimensions can change by as much as 0.12%. These tape dimensional changes will widen or narrow the tape track spacing geometry, resulting in track misregistration with the tape head whose gap spacing geometry is substantially unchanged. Although rotation of the tape head can be used to address the misregistration problem by changing the effective track pitch of the transducer array, this solution requires sophisticated mechanics and skew compensation circuitry.
To illustrate the misregistration problem, assume the transducer array spans x μm between the outermost elements, and the percentage change in tape dimension is 0.12%. The resultant change in the spacing of the tape tracks under the outermost elements will be 0.0012×μm. On the other hand, if the transducer array spans 0.5×μm, then a 0.12% change in tape dimension will only change the tape track spacing under the outermost elements by 0.0006×μm. The 0.5× transducer array span will thus experience only half of the tape dimensional change that is experienced by the x transducer span, such that track misregistration is less likely.
Accordingly, it is desired to have an improved design for a thin film tape head for reading and writing data on magnetic recording tape. What is particularly needed is a head design that provides the ability to reduce the gap pitch of read and write elements.
SUMMARY OF THE INVENTIONThe foregoing problems are solved and an advance in the art is obtained by a planar write module and a hybrid planar write-vertical read bidirectional tape head comprising the write module and one or more vertical read modules. The write module has a write module tape bearing surface for engaging the magnetic recording tape. Plural write elements in the write module each comprise plural thin film layers oriented in generally parallel planar relationship with the write module tape bearing surface. The write elements are arranged so that the transducing gaps of adjacent write elements are generally aligned in a direction that is transverse to a streaming direction of the magnetic recording tape. Each read module has a read module tape bearing surface for engaging the magnetic recording tape. Plural read elements in the one or more read modules each comprise plural thin film layers oriented in generally perpendicular relationship with the read module tape bearing surface.
In one exemplary embodiment disclosed herein, the write elements comprise a pancake coil construction. In another exemplary embodiment disclosed herein, the write elements comprise a helical coil construction. In both embodiments, the write elements may comprise a pair of pole tips providing a write gap at the write module tape bearing surface and a pair of pole pieces extending from the pole tips to a back gap region where the pole pieces are joined, with the back gap region being spaced in a trackwise direction from the write gap. The write elements may be arranged in one or more arrays.
Servo read elements may also be formed on the write module, each comprising plural thin film layers oriented in parallel planar relationship with the write module tape bearing surface. A flux guide construction may be used to form the servo read elements.
The foregoing and other features and advantages of the invention will be apparent from the following more particular description of exemplary embodiments of the invention, as illustrated in the accompanying Drawings, in which:
The invention will now be described by way of exemplary embodiments shown by the drawing figures (which are not necessarily to scale), in which like reference numerals indicate like elements in all of the several views.
Turning now to
Each of the modules 6 and 8 has a read module tape bearing surface 16 for engaging the magnetic recording tape “T.” As additionally shown in
In the exemplary embodiment represented by
It will be seen in
As shown in
Turning now to
It will be seen in
Note that the helical configuration of the write coil 20′ allows the write elements 12′ to have a relatively narrow profile (as compared to the pancake coil configuration described above) that facilitates reduced track pitch. As shown in
Turning to
The microprocessor controller 106 provides overhead control functionality for the operations of the tape drive 100. As is conventional, the functions performed by the microprocessor controller 106 are programmable via microcode routines (not shown) according to desired tape drive operational characteristics. During data write operations (with all dataflow being reversed for data read operations), the microprocessor controller 106 activates the channel adapter 104 to perform the required host interface protocol for receiving an information data block. The channel adapter 104 communicates the data block to the data buffer 108 that stores the data for subsequent read/write processing. The data buffer 108 in turn communicates the data block received from the channel adapter 104 to the read/write dataflow circuitry 110, which formats the device data into physically formatted data that may be recorded on a magnetic tape medium. The read/write dataflow circuitry 110 is responsible for executing read/write data transfer operations under the control of the microprocessor controller 106. Formatted physical data from the read/write data flow circuitry 110 is communicated to the tape interface system 114. The latter includes one or more read/write heads in the read/write head unit 118, and drive motor components (not shown) for performing forward and reverse movement of a tape medium 120 mounted on a supply reel 122 and a take-up reel 124. The drive components of the tape interface system 114 are controlled by the motion control system 112 and the motor driver circuit 116 to execute such tape movements as forward and reverse recording and playback, rewind and other tape motion functions. In addition, in multi-track tape drive systems, the motion control system 112 transversely positions the read/write heads relative to the direction of longitudinal tape movement in order to record data in a plurality of tracks.
In most cases, as shown in
Accordingly, a planar write module and a hybrid planar write-vertical read bidirectional tape head comprising the write module and one or more vertical read modules have been disclosed. While various embodiments of the invention have been shown and described, it should be apparent that many variations and alternative embodiments could be implemented in accordance with the teachings herein. It is understood, therefore, that the invention is not to be in any way limited except in accordance with the spirit of the appended claims and their equivalents.
Claims
1. In a tape drive, a tape head for reading and writing data on a magnetic recording tape, comprising:
- a write module;
- a write module tape bearing surface on said write module for engaging said magnetic recording tape;
- plural write elements in said write module, each of said write elements comprising plural thin film layers oriented in generally parallel planar relationship with said write module tape bearing surface;
- said write elements being arranged so that the transducing gaps of adjacent write elements are generally aligned in a direction that is transverse to a streaming direction of said magnetic recording tape;
- one or more read modules;
- a read module tape bearing surface on each of said read modules for engaging said magnetic recording tape; and
- plural read elements in said one or more read modules, each of said read elements comprising plural thin film layers oriented in generally perpendicular relationship with said read module tape bearing surface.
2. A tape drive in accordance with claim 1 wherein said write module is disposed between two read modules in a trackwise direction relative to said magnetic recording tape.
3. A tape drive in accordance with claim 1 wherein said write elements comprise a pancake coil construction.
4. A tape drive in accordance with claim 1 wherein said write elements comprise a helical coil construction.
5. A tape drive in accordance with claim 1 wherein said write elements comprise a pair of pole tips providing a write gap at said write module tape bearing surface and a pair of pole pieces extending from said pole tips to a back gap region where said pole pieces are joined, said back gap region being spaced in a trackwise direction from said write gap.
6. A tape drive in accordance with claim 1 wherein said write elements are arranged with spaced write gaps.
7. A tape drive in accordance with claim 1 wherein said write elements are arranged in one or more arrays.
8. A tape drive in accordance with claim 1 further including write channel circuitry for said write elements fabricated in thin film layers of said write module.
9. A tape drive in accordance with claim 1 further including servo read elements on said write module, each of said servo read elements comprising plural thin film layers oriented in parallel planar relationship with said write module tape bearing surface.
10. A tape drive in accordance with claim 9 wherein said servo read elements comprise a flux guide construction.
11. A write module for writing data on a magnetic recording tape, comprising:
- a write module tape bearing surface for engaging said magnetic recording tape;
- plural write elements in said write module, each of said write elements comprising plural thin film layers oriented in generally parallel planar relationship with said write module tape bearing surface;
- said write elements comprising a pancake coil construction with a pair of pole tips providing a write gap at said write module tape bearing surface and a pair of pole pieces extending from said pole tips to a back gap region where said pole pieces are joined, said back gap region being spaced in a trackwise direction from said write gap; and
- said write elements being arranged so that the write gaps of adjacent write elements are generally aligned in a direction that is transverse to a streaming direction of said magnetic recording tape.
12. A write module in accordance with claim 11 wherein said write elements are arranged in one or more arrays.
13. A write module in accordance with claim 12 wherein said write gaps are spaced by approximately one gap width.
14. A write module in accordance with claim 11 further including servo read elements on said write module, each of said servo read elements comprising plural thin film layers oriented in parallel planar relationship with said write module tape bearing surface.
15. A write module in accordance with claim 14 wherein said servo read elements comprise a flux guide extending from said write module tape bearing surface to a sensor structure recessed from said write module tape bearing surface.
16. A write module for writing data on a magnetic recording tape, comprising:
- a write module;
- a write module tape bearing surface on said write module for engaging said magnetic recording tape;
- plural write elements in said write module, each of said write elements comprising plural thin film layers oriented in generally parallel planar relationship with said write module tape bearing surface;
- said write elements comprising a helical coil construction with a pair of pole tips providing a write gap at said write module tape bearing surface and a pair of pole pieces extending from said pole tips to a back gap region where said pole pieces are joined, said back gap region being spaced in a trackwise direction from said write gap; and
- said write elements being arranged so that the write gaps of adjacent write elements are generally aligned in a direction that is transverse to a streaming direction of said magnetic recording tape.
17. A write module in accordance with claim 16 wherein said write elements are arranged with spaced write gaps.
18. A write module in accordance with claim 16 wherein said write elements are arranged in one or more arrays.
19. A write module in accordance with claim 16 further including servo read elements on said write module, each of said servo read elements comprising plural thin film layers oriented in parallel planar relationship with said write module tape bearing surface.
20. A write module in accordance with claim 19 wherein said servo read elements comprise a flux guide extending from said write module tape bearing surface to a sensor structure recessed from said write module tape bearing surface.
Type: Application
Filed: Sep 19, 2006
Publication Date: Mar 20, 2008
Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION (Armonk, NY)
Inventors: Robert G. Biskeborn (Hollister, CA), Calvin S. Lo (Saratoga, CA)
Application Number: 11/532,963