Encoder apparatus
AssigneeRenishaw PLC
InventorsColin Keith Howley, Simon Eliot McAdam, Adam Michael Whiting
Life of this patent
Estimating the term…
Abstract
An incremental encoder apparatus including: a scale including a series of periodic features defining an optical incremental scale, and at least one magnetic reference mark; and a readhead. The readhead includes at least one incremental sensor configured to detect light from the optical incremental scale and to output at least one signal dependent thereon, and at least two analogue Hall sensors, each including at least two output terminal pairs, and each configured to switch repeatedly between each output terminal pair so as to reduce any inherent offset in the output of the analogue Hall sensor. The apparatus is configured to determine the presence of the reference mark from the outputs of the at least two analogue Hall sensors.
Claims15
An incremental encoder apparatus comprising:
- a scale comprising a series of periodic features, which define an optical incremental scale, and at least one magnetic reference mark;
- and
- a readhead comprising:
- at least one incremental sensor configured to detect light from the optical incremental scale and to output at least one signal dependent thereon, and
- at least two analogue Hall sensors, each comprising at least two output terminal pairs, and each being configured to switch repeatedly between each output terminal pair,
- wherein the apparatus is configured to generate a reference mark signal from outputs of the at least two analogue Hall sensors, and
- wherein the apparatus is configured so that the reference mark signal is repeatable to within one period of the incremental scale in at least one direction of travel up to a relative velocity of the incremental scale and the readhead of 0.125 m/s.
A readhead for an encoder apparatus comprising:
- at least one incremental sensor configured to detect light from an optical incremental scale and to output at least one signal dependent thereon, and
- at least two analogue Hall sensors, each comprising at least two output terminal pairs, and each being configured to switch repeatedly between each output terminal pair,
- wherein the readhead is configured to determine the presence of a magnetic reference mark on the incremental scale from outputs of the at least two analogue Hall sensors, and
- wherein the readhead is configured so that a reference mark signal, which is generated from the outputs of the at least two analogue Hall sensors, is repeatable to within one period of the incremental scale in at least one direction of travel up to a relative velocity of the incremental scale and the readhead of 0.125 m/s.
Dependencies are inferred from the claim text.