Browse Prior Art Database

Optical Servo for Hard Disk Drive

IP.com Disclosure Number: IPCOM000119596D
Original Publication Date: 1991-Feb-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Ishikawa, J: AUTHOR [+2]

Abstract

Disclosed is a technique of head positioning control for a HDD (Hard Disk Drive). HDD with VCM (Voice Coil Motor) uses a servo signal for read/write head positioning and the servo signal is written on a disk surface. Therefore, a read signal of the servo signal depends on a spindle motor rotation. If the rotational speed of the spindle motor is out of control, a head position cannot be controlled. Described herein is a technique for this situation.

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Optical Servo for Hard Disk Drive

      Disclosed is a technique of head positioning control for
a HDD (Hard Disk Drive).  HDD with VCM (Voice Coil Motor) uses a
servo signal for read/write head positioning and the servo signal is
written on a disk surface.  Therefore, a read signal of the servo
signal depends on a spindle motor rotation.  If the rotational speed
of the spindle motor is out of control, a head position cannot be
controlled. Described herein is a technique for this situation.

      A photo reflector and a black/white label are used for
detection of the head position (see Fig. 1).  It is small enough for
a low end HDD.

      A feedback system is shown in Fig. 2.  A voltage level
indicates the head position.  Thus, PES (Position Error Signal) can
be generated from this voltage and this signal does not depend on the
spindle motor rotation.

      Label pattern is important for this optical servo system. (see
Fig. 3).  TYPE B is better than TYPE A for control range. The control
range (from inner to outer) of TYPE A is narrow.

      Finally, this optical servo system is useful for head
positioning during a spindle motor start period or a spindle motor
stop period.