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Skew Error Detection System for Optical Array Head

IP.com Disclosure Number: IPCOM000107778D
Original Publication Date: 1992-Mar-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Yung, BH: AUTHOR

Abstract

An optical array head is used in the parallel read/write application in an optical data storage system. Due to drive assembly error, media/ spindle runout and media curvature variation from ID to OD, a skew actuator is needed to compensate for the array skew. Hence, a skew error detection system is needed to generate the skew servo signal. This is accomplished in the read path. As return beams are focused by the servo lens onto the servo detector, a mask with a slit at the center and knife edges at both sides (Fig. 1) is installed at the focal plane of the servo detector (Fig. 2). The slit at the center permits the passing of the center beam to generate focus and track error signals, i.e., FES and TES. The two knife edges at either end permit the passing of the two beams at the ends of the array onto the detector assembly.

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Skew Error Detection System for Optical Array Head

       An optical array head is used in the parallel read/write
application in an optical data storage system. Due to drive assembly
error, media/ spindle runout and media curvature variation from ID to
OD, a skew actuator is needed to compensate for the array skew.
Hence, a skew error detection system is needed to generate the skew
servo signal.  This is accomplished in the read path. As return beams
are focused by the servo lens onto the servo detector, a mask with a
slit at the center and knife edges at both sides (Fig. 1) is
installed at the focal plane of the servo detector (Fig. 2). The slit
at the center permits the passing of the center beam to generate
focus and track error signals, i.e., FES and TES. The two knife edges
at either end permit the passing of the two beams at the ends of the
array onto the detector assembly.  These two beams generate two TESs,
and these TESs are compared to generate a skew error signal (SES) to
drive the skew actuator.