Two-dimensional scale structures and method usable in an absolute position transducer

US6781694B2 · kind B2 · utility

Assignee

• Mitutoyo Corporation · JP

Inventors

• Michael Nahum · Kirkland, US
• Benjamin Keith Jones · Seattle, US
• Patrick A. Renalds · Bothell, US
• Avron Zwilling · Redmond, US
• Kim W. Atherton · Kirkland, US

Key dates

• Filing date: Sep 13, 2002
• Grant date: Aug 24, 2004
• Expiry date: Jan 20, 2023

Classification

• Technology area (CPC G): Physics
• CPC primary: G01D2205/90
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

An absolute 2D position-sensing device is usable to measure the relative position of two elements. A 2D absolute scale includes an integrated 2D absolute scale pattern extending over the 2D scale area along each measuring axis of the scale. The integrated 2D absolute scale pattern includes a plurality of periodic portions interleaved with a plurality of non-periodic portions along each axis. Each periodic portion includes a plurality of periodically-placed scale elements. Each non-periodic portion includes a plurality of code elements indicative of an absolute measurement value. The code elements may have a length that is narrower along each measuring axis is than the length of the periodic scale elements along each measuring axis. The offset of the periodically-placed elements relative to a readhead of the device is combined with the absolute measurement value to determine an absolute position.