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

• US 6,701,634 B2
• Filed: 08/02/2002
• Issued: 03/09/2004
• Est. Priority Date: 11/30/1999
• Status: Expired due to Fees

• Current Assignee: Renishaw PLC
• Original Assignee: Renishaw PLC
• Inventors: Mackintosh, Thomas I, Hoodless, Richard J, Henshaw, James R, Holden, Peter G, McMurtry, David R
• Primary Examiner(s): Gutierrez, Diego
• Assistant Examiner(s): Guadalupe, Yaritza
• Application Number:
  US10/209,921
• Publication Number:
  US 20020184782A1
• Time in Patent Office: 585 Days
• Field of Search: 337/06, 337/07, 337/08, 337/10, 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 scale tensioning device suitable for tensioning a scale readable by a readhead while the scale is mounted to a substrate, the device comprising:

a loading part, a preloadable member and a securement, the loading part being operable to preload the preloadable member and to release the preload, so as to urge the scale into tension while the scale is mounted to the substrate, the securement being operable to maintain the scale in tension while the scale is mounted to the substrate, and

the preloadable member being removable from a substrate while the scale remains tensioned on the substrate.

2. The measurement scale tensioning device of claim 1, wherein the securement secures each end of the scale to the substrate.

3. The measurement scale tensioning device of claim 1, wherein the preloadable member includes a resilient part.

4. The measurement scale tensioning device of claim 3, wherein the loading part includes an eccentric pin, rotatable to effect the preloading and release of the preload.

5. A method for tensioning a measurement scale comprising the steps in any suitable order of:

providing a measurement scale and a scale tensioner;

mounting the scale to a substrate;

securing one end of the scale to the substrate;

preloading the scale tensioner;

securing the tensioner to the substrate adjacent another end of the scale;

releasing the preload in the tensioner to cause a tension in the scale;

securing the other end of the scale to the substrate while maintaining the tension in the scale; and

releasing the securement of the tensioner whilst maintaining the tension in the scale.

6. The method of claim 5, further comprising the steps of

preloading the scale tensioner again;

re-securing the tensioner to the substrate adjacent the other end of the scale;

releasing the preload in the tensioner;

releasing the securement of the scale at the said other end, thereby allowing further tension in the scale;

re-securing the said other end of the scale to the substrate, whilst maintaining the further tension in the scale;

releasing the securement of the tensioner; and

repeating the aforementioned steps until the scale extends substantially no more on application of the further tension.

7. The method of claim 5, further comprising the step of removing the tensioner from the substrate following securement of the scale at the other end of the scale.

8. The method of claim 6, further comprising the step of removing the tensioner from the substrate following re-securement of the scale at the other end of the scale.

9. The method of claim 5, wherein the step of securing the scale to the substrate includes the provision of a track to hold the scale to the substrate.