Position measuring apparatus with multiple scanning locations

US4990767A · kind A · utility

Assignee

• DR. JOHANNES HEIDENHAIN GMBH · DE

Inventors

• Alfons Ernst · Traunreut, DE
• Walter Schmitt · Traunreut, DE
• Norbert Huber · Erlangen, DE

Key dates

• Filing date: Jul 22, 1988
• Grant date: Feb 5, 1991
• Expiry date: Jul 22, 2008

Classification

• Technology area (CPC G): Physics
• CPC primary: G01D5/24404
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A measuring device is provided in which a graduated plate is scanned in at least two scanning locations. The scanning signals from the different scanning locations are transmitted to a testing circuit which determines whether the phase displacement between the scanning signals exceeds a limit value. If the limit value is exceeded, one of the scanning locations is weighted higher than the other. The weighting is implemented by increasing the components of the signals from one scanning location while decreasing the components from the signals from the other scanning location.