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Browse Prior Art Database

Erase Verification in an Optical Drive

IP.com Disclosure Number: IPCOM000113878D
Original Publication Date: 1994-Oct-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Call, DE: AUTHOR [+4]

Abstract

An erase or write operation is sensed by detecting that the laser power exceeds some threshold, which signals the drive controller that the intended erase or write operation took place in an optical drive.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 76% of the total text.

Erase Verification in an Optical Drive

      An erase or write operation is sensed by detecting that the
laser power exceeds some threshold, which signals the drive
controller that the intended erase or write operation took place in
an optical drive.

      The Figure shows a block diagram of a laser driver circuit with
an erase/write detector.  Read power control loop consist of laser 1,
light 2 emitted by laser 1, photo-detector 3 which senses a portion
of the light 2, transimpedance amplifier 4 which converts a
photo-current into a proportional voltage, error amplifier 5 which
amplifies the difference between the output voltage of the
transimpedance amplifier 4 and read power reference signal 6, and
finally a voltage to current converter 7 which drives the laser 1.  A
write/erase current source is outside the power control loop, since
during erase/write operations the power control loop is opened by the
analog switch 9.

      The erase/write power detector consists of voltage comparator
10, one input of which is connected to the output of transimpedance
amplifier 4, the other input is connected to the erase\write power
threshold 11.  The erase/write power threshold is chosen to be
somewhat above the maximum read power level threshold such that
exceeding this level during an erase/write operation would, at the
least, significantly alter any old recorded data in the sector.  When
the laser power exceeds the erase/write power threshold, the
comparator outpu...