US 5,243,187 AGranted

High resolution absolute encoder for position measurement

AssigneeTeldix GmbH

InventorEckart Hettlage

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Abstract

An encoder comprises a rotatable or longitudinally displaceable body having a plurality of sawtooth-shaped regions which lie one behind the other in the direction of rotation or displacement. Each sawtooth-shaped region is separated by a steep edge that extends transversely to the direction of rotation or displacement. Upon movement of the body due to its sawtooth-shaped configuration, the distance of the surface of the sawtooth-shaped regions changes relative to a distance sensor arrangement. An evaluation circuit receives the output signals of the sensor arrangement and determines the rotation angle or the displacement of the body. The sensor arrangement comprises two distance sensors being offset relative to one another in the direction of movement by less than one sawtooth-shaped region forming distance signals, with the distance signals input to the evaluation circuit. The evaluation circuit evaluates only one of the distance signals in order to determine the angle or displacement of the body. The entire surface of the rotationally or longitudinally displaceable body facing the distance sensors has coinciding sawtooth-shaped regions. A rough measuring system is provided whose signals are fed to the evaluation circuit to characterize the individual sawtooth-shaped regions. An offset signal which characterizes the rotation angle or the displacement is associated with the individual sawtoothshaped regions in the evaluation circuit. The absolute rotation angle or displacement signal is formed in the evaluation circuit from the applicable offset signal and the signal of the presently employed distance sensor.

Claims8

Dependent claims

An encoder comprising:

(a) a rotatable or longitudinally displaceable body having a plurality of sawtooth-shaped regions which lie one behind the other in the direction of rotation or displacement, with each sawtooth-shaped region being separated form the subsequent sawtooth-shaped region by a steep edge that extends transversely to the direction of rotation or displacement and, upon movement of the body due to its sawtooth-shaped configuration, a distance of a surface of the sawtooth-shaped regions changes relative to a distance sensor arrangement;
(b) an evaluation circuit which receives the output signals of the distance sensor arrangement and determines therefrom a rotation angel or a displacement of the body,
wherein:
(a) the sensor arrangement comprises two distance sensors which are offset relative to one another in the direction of movement by less than one sawtooth-shaped region in order to form distance signals, with the distance signals being fed to the evaluation circuit and wherein the evaluation circuit evaluates, in each case, only one of the distance signals in order to determine the angle or to determine the displacement of the body;
(b) the entire surface of the rotationally or longitudinally displaceable body facing the distance sensors has coinciding sawtooth-shaped regions;
(c) a rough measuring system is provided whose signals (not shown) are fed to the evaluation circuit to characterize the individual sawtooth-shaped regions;
(d) an offset signal characterizing the rotation angle or the displacement is associated with the individual sawtoothshaped regions in the evaluation circuit;
and
(e) an absolute rotation angel or displacement signal is formed in the evaluation circuit from the applicable offset signal and the signal of the presently employed distance sensor.

6 more elements

Dependencies are inferred from the claim text.