Browse Prior Art Database

Active Beam Bender for Skew Compensation Introduction

IP.com Disclosure Number: IPCOM000106295D
Original Publication Date: 1993-Oct-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 4 page(s) / 84K

Publishing Venue

IBM

Related People

Bargerhuff, RA: AUTHOR [+2]

Abstract

Parallel read/write (r/w) systems are needed to enhance data rate in an optical data storage system. Due to the optical media radius of curvature change from ID to OD, drive assembly tolerances, inherent media and spindle runouts, it is necessary to introduce a skew actuator to rotate the parallel r/w beams to minimize track mis-registration (TMR) on all channels (Fig. 1). The art of generating skew error signal from a parallel r/w beam system is discussed in [1]. How to minimize angular and lateral skew components is described in [2]. Multiple beam rotation, using a Dove prism, is illustrated in [3]. This actuator design is functional but too bulky for the current optical head design trend. This disclosure proposes a solution.

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Active Beam Bender for Skew Compensation Introduction

      Parallel read/write (r/w) systems are needed to enhance data
rate in an optical data storage system.  Due to the optical media
radius of curvature change from ID to OD, drive assembly tolerances,
inherent media and spindle runouts, it is necessary to introduce a
skew actuator to rotate the parallel r/w beams to minimize track
mis-registration
 (TMR) on all channels (Fig. 1).  The art of generating skew error
signal from a parallel r/w beam system is discussed in [1].  How to
minimize angular and lateral skew components is described in [2].
Multiple beam rotation, using a Dove prism, is illustrated in [3].
This actuator design is functional but too bulky for the current
optical head design trend.  This disclosure proposes a solution.

      Current optical drive design embodies a fixed optical element
(FOE) and the collimated beams are focused on the media using a beam
bender and an objective lens (Fig. 2).  The invention activates the
beam bender element so that the tilting introduced by the beam bender
rotates the multiple beams.

      Implementation - Two strips of stacked piezoelectric (PZT)
elements are bonded on the beam bender element as shown in Fig. 3.
Applying voltage across the PZT moves either side of the beam bender
up.  To rotate the multiple beams clockwise, a voltage is applied to
the PZT on the right side of the beam bender.  To rotate the multiple
beam counterclockwise, a volta...