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Fleur-De-Lis Skew Servo-Pattern for Magnetic-Tape

IP.com Disclosure Number: IPCOM000224389D
Publication Date: 2012-Dec-17
Document File: 5 page(s) / 82K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method to make use of a novel servo pattern to detect the skew angulation of the tape head relative to the magnetic tape. This enables the active skew-servoing of the head relative to the tape, for the purposes of supporting increased data density and improved error correction. The novel contribution of this invention is that only one servo read-element is needed to detect the skew (angulation) of the magnetic tape head relative to the magnetic tape.

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This is the abbreviated version, containing approximately 51% of the total text.

Page 01 of 5

Fleur-De-Lis Skew Servo-Pattern for Magnetic-Tape

A method is needed to detect the skew angulation of the tape head relative to the magnetic tape. This would enable the active skew-servoing of the head relative to the tape, for the purposes of supporting increased data density and improved error correction.

Previous work in this area required two servo read-elements. The novel contribution of this invention is that only one servo read-element is needed to detect the skew (angulation) of the magnetic tape head relative to the magnetic tape. This may involve the mis-angulation of just the head, just the tape, or both the head and the tape relative to each other.

The invention makes use of a novel servo pattern shown in Figures 1-4. Tape system 100 has tape 102 with skew-servo pattern 110-112-114, which comprises skew-servo track 110 written perpendicular to the longitudinal "X" direction (length direction) of the magnetic tape. Skew-servo track 112 is written at an angle +a in the counterclockwise direction. Skew-servo track 114 is written at an angle -a in the clockwise direction (equal angle in magnitude and opposite direction from skew servo track 112). Magnetic tape head 104 has servo read-element 106 which reads skew servo pattern 110-112-114, as well as the timing-based-servo (TBS) pattern, /////\\\\\////\\\\, or the /\/ /\/ N-pattern timing based servo, or the /\/\ /\/\ M-pattern timing based servo (not shown in Figures 1-4 for simplicity).

The skew-servo pattern 110-112-114 is written all at the same time, and that angles +a and -a are small angles, measured in the range of milli-radians to micro-radians.

Figure 1: Fleur-De-Lis Skew-Servo Pattern

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Page 02 of 5

The way this invention works is based on the signal read by servo read-element 136A in Figure 2, 136B in Figure 3, and 136C in Figure 4. In Figure 2, servo read-element 136A is perpendicular to the longitudinal direction of the tape (zero skew relative to servo track 110) and hence has the ideal read signal 130A. Servo read-element 136A is skewed relative to servo track 112 and 114, hence has distorted read signals 132A and 134A respectively.

Figure 2: Servo read-element has zero skew

In Figure 3, servo read-element 136B is skewed an angle of +a relative to the longitudinal direction of the tape and hence has the ideal read signal 132B. Servo read-element 136B is skewed an angle "+a" relative to servo track 110 and skewed an angle "+2a" relative to servo track 114, hence has distorted read signals 130B and 134B respectively, with read signal 134B distorted more than read signal 130B because of the greater skew between servo read-element 136B and servo track 11...