Browse Prior Art Database

Retard Servo Control System

IP.com Disclosure Number: IPCOM000120117D
Original Publication Date: 1991-Mar-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 2 page(s) / 58K

Publishing Venue

IBM

Related People

Kagami, N: AUTHOR [+3]

Abstract

Disclosed is a technique for retarding controlling a fine actuator of an optical disk drive pickup to achieve a reliable track access using a relative positioning error signal which indicates objective lens position relating to an optical path. The technique is widely applicable to any optical pickup system which consists of a fine tracking actuator and a coarse access linear actuator.

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Retard Servo Control System

      Disclosed is a technique for retarding controlling a fine
actuator of an optical disk drive pickup to achieve a reliable track
access using a relative positioning error signal which indicates
objective lens position relating to an optical path.  The technique
is widely applicable to any optical pickup system which consists of a
fine tracking actuator and a coarse access linear actuator.

      The technique will be best understood with reference to Fig. 1
which schematically shows a fine actuator retarding servo control
system during track access.  During the track access, a fine actuator
1 is mainly controlled based on a TES (Track Error Signal) 2 which
inputs to a fine actuator controller 10.  On the other hand, a coarse
access linear actuator 3 is controlled based on a RPE (Relative
Positioning Error Signal) 4 which indicates the position of an
objective lens 5 relating to an optical path 6 which inputs to a
coarse actuator controller 11.  The velocity of the fine actuator 1
is generally faster than that of the coarse actuator 3.  Therefore,
the fine actuator retarding servo system is required in order to
avoid the fine actuator crashing mechanically.

      In accordance with this technique, the RPE signal 4 is added to
a fine actuator driving signal 12 using an adder 7. Before the adder
7, the phase of the RPE signal 4 is leaded using a filter 8 in
order to obtain a smooth retarding signal 13.  The gain of the filter
...