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Relative Position Error Sensor with Auto-Collimator Detector for Optical Drive

IP.com Disclosure Number: IPCOM000117886D
Original Publication Date: 1996-Jul-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Hirasaka, Y: AUTHOR [+2]

Abstract

Disclosed is a method for obtaining the relative error signal of a galvano mirror angle by using a differential signal, created by the optical spots which are projected to the two detectors through an auto-collimator type package of detectors.

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This is the abbreviated version, containing approximately 100% of the total text.

Relative Position Error Sensor with Auto-Collimator Detector for
Optical Drive

      Disclosed is a method for obtaining the relative error signal
of a galvano mirror angle by using a differential signal, created by
the optical spots which are projected to the two detectors through an
auto-collimator type package of detectors.

      The Figure shows an example of this apparatus.  The optical
beam (1) from the light source reflected by a galvano mirror (2) is
used for tracking to the data area on an optical disk (3).  Then the
beam (1) is divided into two directions by a prism (4).  One beam (5)
is bent to an objective lens (6) and is used for reading the data
signal or obtaining the focus and tracking error signal.  Another
beam (13) goes through the prism (4) and goes to an auto-collimator
type detector (7).  By the auto-collimator type package, the beam is
focused on the detectors (10,11).  The angle of the galvano mirror is
obtained by the differential signal (12) from these detectors
(10,11).  The signal gain can be greater than that without the
package (7).