Dynamic magnetic information storage or retrieval – Automatic control of a recorder mechanism – Controlling the head
Reexamination Certificate
1999-12-21
2003-04-08
Hudspeth, David (Department: 2651)
Dynamic magnetic information storage or retrieval
Automatic control of a recorder mechanism
Controlling the head
C360S076000
Reexamination Certificate
active
06545837
ABSTRACT:
FIELD OF THE INVENTION
This invention concerns techniques for increasing areal recording density in linear magnetic recording systems.
BACKGROUND OF THE INVENTION
There are two basic approaches to increasing areal data recording density. The first is to increase bit density, and the second is to increase track density. Continuous track following servo schemes, physically narrower data tracks, or both increase track density in linear recording systems (such as those using flexible magnetic tape as the recording medium). The problem with physically narrower data tracks is that they require physically narrower recording gaps, which produce smaller signal amplitudes. At some point, the signals are too small to be decreased further without loss of signal.
One approach to increasing track density is azimuth recording, in which adjacent tracks are recorded by recording gaps slanted relative to each other. The signals so produced are out of phase with each other and thus can be discriminated from each other even if they physically overlap. Thus, physically larger recording gaps, large enough to produce adequately sized signals, may be used.
SUMMARY OF THE INVENTION
One aspect of the invention is a method of recording data on a linear medium having a servo track. A head having parallel read and write head gaps is maintained constant distances from the servo track, thus defining the locations of data tracks. During writing in a first data track, the head is tilted at an angle &thgr; with respect to the servo track. During writing in a second data track, the head is tilted to the supplementary angle of &thgr; with respect to the servo track, i.e., (180°−&thgr;). The location of the head and the angle of the head are both independently adjustable. This allows the data tracks to be very closely spaced together without loss of accurate tracking due to errors such as tape slope (in the case of recording on tape), and longitudinal tracking error. Therefore, areal recording density is increased.
Another aspect of the invention is a linear data recording system. The system comprises a linear medium having a servo track, a head having parallel read and write gaps, and first and second head servo mechanisms. The first, or coarse, servo mechanism maintains the head at first and second distances from the servo track. The second, or fine, servo head mechanism maintains the head at an azimuth angle &thgr; to the servo track when the head is at the first distance from the servo track (and thus positioned over a first data track); it also maintains the head at the supplementary angle to the servo track when the head is at the second distance (and thus positioned over a second data track immediately adjacent the first data track).
A third aspect of the invention is a linear data recording medium comprising at least one servo track and at least two data tracks immediately adjacent to each other. As just described, data is recorded on the immediately adjacent data tracks at supplementary angles measured relative to the servo track.
REFERENCES:
patent: 5132861 (1992-07-01), Behr et al.
patent: 5371638 (1994-12-01), Saliba
patent: 6141174 (2000-10-01), Judge et al.
patent: 6188532 (2001-02-01), Albrecht et al.
Hudspeth David
Imation Corp.
Levinson Eric D.
Slavitt Mitchell
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