Browse Prior Art Database

High Resolution Inductive Position Sensor

IP.com Disclosure Number: IPCOM000040522D
Original Publication Date: 1987-Nov-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Korth, HE: AUTHOR

Abstract

State-of-the-art thin-film magnetic heads (1 in Fig. 1) with open coils are used as inductance sensors in a collinear set-up on a ceramic block (2 in Fig. 1) to detect the relative position of a periodic metal grid structure (3 in Figs. 1 and 2) in the submicron range. Fig. 1 is a cross-sectional view of the grid structure in the direction of movement of ceramic block 2. A circuit (Fig. 3), comprising, say, three inductance sensors, utilizes an interpolation concept known per se, by means of which the grid period is divided into subportions by comparing the inductance of each coil with the average value of the various coils. The three sensor coils 4 of the magnetic heads are wired to form three identical resonators 5. Resonators 5 are used to feed the output of an oscillator circuit 6 to a set of differential amplifiers 7.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 100% of the total text.

Page 1 of 2

High Resolution Inductive Position Sensor

State-of-the-art thin-film magnetic heads (1 in Fig. 1) with open coils are used as inductance sensors in a collinear set-up on a ceramic block (2 in Fig. 1) to detect the relative position of a periodic metal grid structure (3 in Figs. 1 and 2) in the submicron range. Fig. 1 is a cross-sectional view of the grid structure in the direction of movement of ceramic block 2. A circuit (Fig. 3), comprising, say, three inductance sensors, utilizes an interpolation concept known per se, by means of which the grid period is divided into subportions by comparing the inductance of each coil with the average value of the various coils. The three sensor coils 4 of the magnetic heads are wired to form three identical resonators
5. Resonators 5 are used to feed the output of an oscillator circuit 6 to a set of differential amplifiers 7.

(Image Omitted)

When the oscillator is tuned to a frequency at the slope of the resonator frequency response peak, a small variation of the coil inductance will lead to a major change in the electrical resonator impedance. A corresponding current is fed to the differential amplifiers and compared with the average value of all the coils. After rectification and integration, digitized signals are obtained. The sequence of these signals V0, V120, V240 allows monitoring the position of the coils with respect to the grid.

1

Page 2 of 2

2

[This page contains 4 pictures or other non-text objects]