Linear encoder

• US 5,511,321 A
• Filed: 07/26/1995
• Issued: 04/30/1996
• Est. Priority Date: 06/23/1993
• Status: Expired due to Term

• Current Assignee: Dr. Johannes Heidenhain GmbH
• Original Assignee: Dr. Johannes Heidenhain GmbH
• Inventors: Nelle, Gunther
• Primary Examiner(s): Fulton, Christopher W.
• Application Number:
  US08/507,741
• Time in Patent Office: 279 Days
• Field of Search: 33/704, 33/702, 33/703, 33/DIG. 19
• US Class Current: 33/704
• CPC Class Codes: G01B 5/0014 due to temperature on machine tools B23Q11/0003
• CPC Class Codes: G01D 5/34707 Scales; Discs, e.g. fixation, fabrication, compensation
• CPC Class Codes: Y10S 33/19 Thermal expansive

Abstract

A linear encoder for measuring a relative position of two objects and including a scale having a coefficient of thermal expansion between 2.5×10^-6 K^-1 and 3.5×10^-6 K^-1 approximately, and attachable to one of the objects, and a device for scanning the scale and attachable to the other of the objects.

Claims

1. A linear encoder for use in a machine for manufacturing workpieces having a coefficient of thermal expansion approximately between 2.5×

10^-6 K^-1 and 3.5×

10^-6 K^-1, the machine having two movable relative to each other objects, said linear encoder being designed for measuring a relative position of the two objects, and said linear encoder comprising a scale having a coefficient of thermal expansion approximately between 2.5×

10^-6 K^-1 and 3.5×

10^-6 K^-1, selected to substantially correspond to the coefficient of thermal expansion of the workpieces to be manufactured on the machine, said scale being attachable to one of the two objects, and a device for scanning said scale and attachable to another of the two objects.

2. A linear encoder as set forth in claim 1, wherein the scale is formed of one of monocrystaline silicium, glass, and glass-ceramics.

3. A linear encoder as set forth in claim 1, wherein the scale comprises a unit formed of a scale carrier and a scale carrier element.

4. A linear encoder as set forth in claim 3, wherein the scale carrier is attached to the scale carrier element with a highly elastic glue.

5. A linear encoder as set forth in claim 3, wherein the scale carrier is fixedly attached to the scale carrier element at one point.

6. A linear encoder as set forth in claim 3, further comprising a tensioning device for connecting one end of the scale carrier to the scale carrier element.