Servo writer having slanted timing pattern read and write heads

Details Servo writer having slanted timing pattern read and write heads Servo writer having slanted timing pattern read and write heads

1999-12-01

2003-02-18

Hudspeth, David (Department: 2651)

Dynamic magnetic information storage or retrieval

General processing of a digital signal

Data in specific format

C360S121000, C360S125330

Reexamination Certificate

active

06522490

ABSTRACT:

TECHNICAL FIELD
The present invention generally relates to magnetic read and write heads used to read and write information in tracks on a magnetic recording medium such as a tape, and more particularly, to a servo writer having optimized utilization of head space without compromising track width or signal-to-noise ratio characteristics.
BACKGROUND ART
Generally, narrow, multi-track magnetic recording devices have been developed as a way of increasing data density storage capacity for a tape media. However, because the lateral spacing of the tracks is very small, servo systems have been developed to record servo pattern/tracking data onto a tape which can be read during use of the tape by a recording device to allow precise positioning control of the data read and write heads relative to the tape. The servo pattern is typically formed as a sequence of frequencies recorded on predetermined areas of a tape, and allow a servo reader to accurately reference track location.
As shown in
FIGS. 1 and 2
, a servo write head arrangement
10
was developed by the assignee of the present invention to utilize four modules
12
through
18
to provide high tolerance placement of the servo pattern in a single pass of the tape. Each module includes a plurality of servo write heads located in the same gap line, each of which is arranged to operate in conjunction with similarly arranged servo write heads located on the remaining modules to form individual, parallel servo tracks on the tape. In this servo head design, a timing pattern write or read head is located in each module gap line between the servo write heads and the edges of the tape.
More specifically, as best seen in
FIG. 2
, a first module
12
includes a timing pattern writer
20
formed in the same gap line as a wide leading writer
22
. While only one end/edge is shown in
FIG. 2
for clarity of description, it is to be understood that each module is similarly arranged with an appropriate timing pattern writer or reader at the other edge. Referring again to
FIG. 2
, a second module
14
includes a timing reader
24
and a first servo erase writer
26
, and a third module
16
includes a timing reader
28
and a second servo erase writer
30
. A fourth module
18
includes a timing reader
32
and a track identification writer
34
. As noted above, each timing writer/reader is located between the edge of the tape and the servo writers. Each head includes a top and bottom pole respectively designated as
36
and
38
.
In operation, a tape is moved past the servo writer head as indicated by the arrow. Each track of the servo pattern is formed from the combined operations of the leading edge writer, erase writers, and track identification writer. In this servo writer arrangement, placement of the timing pattern write and read heads between the servo write heads and the edges of the tape is advantageous because data is not typically recorded in the outer edge regions of the tape. Thus, overall utilization of the tape width is improved.
However, placement of the timing pattern at the edges of the tape is also problematic because the edges of the tape are the most susceptible area for tape guiding problems. Unfortunately, because typical timing pattern write and inductive read heads are formed with symmetry down the center of the head and include coils that flare around the back gap area of the head, these heads are limited in how close they can be placed to the adjacent servo write heads. Thus, placement of the timing pattern heads is forced to be closer to the tape edge, thereby potentially exasperating the tape edge problem.
In addition, in order to improve signal-to-noise ratio of the signal used for the timing pattern, it is desirable to maximize track width as well as the number of windings for each timing pattern head. Again, because of the symmetrical layout, these factors must be compromised in order to position the timing heads as close as possible to the servo write heads. As a result, a need exists for a servo writer arrangement which allows closer placement of timing pattern read and write heads to the servo heads without compromising track width or signal-to-noise ratio characteristics.
DISCLOSURE OF THE INVENTION
It is therefore an object of the present invention to provide a servo writer having a head arrangement which permits reading and writing of timing pattern data at an edge of a magnetic recording medium while minimizing the impact of possible tape guiding errors attendant with utilizing the edges for writing and reading of such timing pattern data.
It is another object of the present invention to provide a magnetic head design having signal readers and writers arranged to provide optimized signal location and width on a magnetic recording medium without compromising the number of coil windings that can be wound on associated inductive read/write heads.
It is another object of the present invention to provide a servo writer having timing pattern readers and writers arranged to provide optimized timing pattern location and width without compromising the number of coil windings that can be wound on the timing pattern read/write heads.
In accordance with these and other objects, the present invention provides a servo writer for writing servo tracking signals on a multi-track recording medium having a first servo write head positioned to form a servo track on the recording medium, and a timing pattern write head positioned adjacent the first servo write head so as to form a timing signal track on the recording medium between the servo track and an edge surface of the recording medium, wherein the timing pattern write head is formed having a top and bottom pole asymmetrically oriented relative to the center of the head so as to slant the recording gap of the head toward the servo write head and away from the edge surface of the recording medium.
In accordance with one aspect of the present invention, the servo writer further includes a second servo write head positioned to write signals on the servo track formed by the first servo write head, and a timing pattern inductive read head positioned adjacent the second servo write head so as to read the timing signal formed by the timing pattern write head, wherein the timing pattern read head is formed having a top and bottom pole asymmetrically oriented relative to the center of the head so as to slant the read gap of the head toward the second servo write head and away from the edge surface of the recording medium.
In accordance with another aspect of the present invention, a second timing pattern write head is positioned in the same gap line as the other timing pattern write head so as to form a timing signal track along the other edge surface of the recording medium, wherein the second timing pattern write head comprises a top and bottom pole having an asymmetrical orientation relative to the center of the head so as to slant the recording gap of the head away from the other edge surface. One or more additional timing pattern inductive read heads can also be positioned so as read the timing signal track along the other edge surface of the recording medium. These inductive read heads are also formed with a top and bottom pole having an asymmetrical orientation relative to the center of the head so as to slant the read gap of the head away from the other edge surface.
In accordance with still another aspect of the present invention, a timing pattern write head for use in a servo writer to form a timing signal track on a recording medium between a servo track and an edge surface of the recording medium includes a top and bottom pole having an asymmetrical orientation relative to the center of the head so as to slant the recording gap of the head away from the edge of the recording medium. The asymmetrical orientation further positions a back gap layer away from an adjacent servo write head so as to maximize head space available for a coil, thereby allowing the number of turns on the coil to be as large as possible.
In accordance with yet another aspect of the present inv

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