Measurement apparatus including a track for a measurement scale and apparatus for tensioning the scale

• US 6,772,531 B1
• Filed: 11/27/2000
• Issued: 08/10/2004
• Est. Priority Date: 11/30/1999
• Status: Expired due to Fees

• Current Assignee: Renishaw PLC
• Original Assignee: Renishaw PLC
• Inventors: McMurtry, David R, Mackintosh, Thomas I, Hoodless, Richard J, Henshaw, James R, Holden, Peter G
• Primary Examiner(s): Gutierrez, Diego
• Assistant Examiner(s): Guadalupe, Yaritza
• Application Number:
  US09/721,880
• Time in Patent Office: 1,352 Days
• Field of Search: 337/06--10, 33D/IG.1
• US Class Current: 33/706
• CPC Class Codes: F16C 29/005 Guide rails or tracks for a linear bearing, i.e. adapted for movement of a carriage or bearing body there along
• CPC Class Codes: F16C 41/007 Encoders, e.g. parts with a plurality of alternating magnetic poles
• CPC Class Codes: G01D 5/34707 Scales; Discs, e.g. fixation, fabrication, compensation
• CPC Class Codes: G01D 5/34746 Linear encoders
• CPC Class Codes: Y10S 33/01 Magnetic

Abstract

There is disclosed: a measurement scale suitable for use with scale reader for determining displacement; various tracks all for holding the scale and all having a channel into which the scale is magnetically attracted; and a scale tensioner which in use tensions the scale in situ by release of a preload, prior to the scale being secured to a substrate, the tensioner being removable thereafter.

Claims

1. A measurement apparatus comprising:

a measurement scale;

a readhead relatively movable along the scale for reading the scale; and

a scale track holding the scale, the track having magnetisable material for causing magnetic attraction force between the scale and the track, the scale being spaced from the magnetisable material, the magnetic attraction force between the scale and the magnetisable material allowing relative movement between the scale and the track.

2. A measurement apparatus, comprising:

a measurement scale;

a readhead relatively movable along the scale for reading the scale; and

a scale track having a channel and magnetisable material, the scale being held magnetically to the channel, the scale being spaced from the magnetisable material, a magnetic attraction force between the channel and the track allowing relative movement between the scale held in the channel and the track.

3. A measurement apparatus, comprising:

a measurement scale;

a readhead relatively moveable along the scale for reading the scale;

a scale track holding the scale, the track having magnetisable material for causing magnetic attraction force between the scale and the track, the scale being spaced from the magnetisable material, the magnetic attraction force between the scale and the magnetisable material allowing relative movement between the scale and the track; and

a scale tensioner for tensioning the scale on the track.