Browse Prior Art Database

Integrated Voice Control Monitor/Rotary Variable Differential Transformer Position Sensor for Actuator Position Control

IP.com Disclosure Number: IPCOM000105843D
Original Publication Date: 1993-Sep-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Chiang, WW: AUTHOR [+2]

Abstract

Disclosed is a method of obtaining, with very low cost, the position signal of an actuator used in magnetic or optical drive. This invention integrates the force-generating device (Voice Coil Motor) with the position-sensing device (Rotary Variable Differential Transformer) by using the motor coil also as the primary coil of the RVDT, and sharing the magnetic circuit of the VCM with the RVDT. Only the secondary coils of the RVDT and its driver/decoder electronics are required which keeps the additional cost to a minimum level.

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Integrated Voice Control Monitor/Rotary Variable Differential Transformer Position Sensor for Actuator Position Control

      Disclosed is a method of obtaining, with very low cost, the
position signal of an actuator used in magnetic or optical drive.
This invention integrates the force-generating device (Voice Coil
Motor) with the position-sensing device (Rotary Variable Differential
Transformer) by using the motor coil also as the primary coil of the
RVDT, and sharing the magnetic circuit of the VCM with the RVDT.
Only the secondary coils of the RVDT and its driver/decoder
electronics are required which keeps the additional cost to a minimum
level.

      This invention has the potential of increasing the actuator
seek and tracking performance, providing position information for
servo writing, and even replacing the traditional position servo
system depending on the accuracy of the embodiment.

      Fig. 1 shows one embodiment example of the new design
integrated to a rotary actuator using a "flat coil" VCM for the
magnetic disk drive.  Fig. 2 shows how the RVDT driver signal is
mixed into the nominal VCM driver signal, and how the RVDT output
signals from the secondary coils are demodulated for the actuator
position signal.