Browse Prior Art Database

High Resolution Magnetic Encoder

IP.com Disclosure Number: IPCOM000029339D
Original Publication Date: 2004-Jun-24
Included in the Prior Art Database: 2004-Jun-24
Document File: 1 page(s) / 99K

Publishing Venue

IBM

Abstract

Disclosed is a method to increase the resolution of magnetic encoders using a splitted data track and a sensor array.

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High Resolution Magnetic Encoder

The proposed magnetic encoder disk uses concentric magnetic patterns on a rotating disk. Instead of using only one track for all the magnetic bits to create the required information(count-per-revolution, CPR), the information is split into n tracks on which the magnetic bits are distributed evenly. The phase of each bit pattern is shifted from track to track by 2*pi/n where n is the number of tracks.

    As a consequence of the split tracks the number of sensors in the sensor array must be increased by n.

The picture below shows an example using four tracks and N bits per track .

The sensor array can be produced in a Wafer -Process. No external inter sensor alignment is necessary.

Advantages of the proposed solution:

The resolution limit as determined by mechanical tolerances can be increased by the factor n. The resolution limit as determined by the magnetic spacing can be increased by the factor n.

The reading frequency is reduced by a factor of n . Hence the electronics can be made cheaper.

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