Length measuring device

• US 7,121,015 B2
• Filed: 06/27/2003
• Issued: 10/17/2006
• Est. Priority Date: 08/08/2002
• Status: Expired due to Term

• Current Assignee: Dr. Johannes Heidenhain GmbH
• Original Assignee: Dr. Johannes Heidenhain GmbH
• Inventors: Böge, Ludwig
• Primary Examiner(s): GUADALUPE, YARITZA
• Application Number:
  US10/524,170
• Publication Number:
  US 20060107545A1
• Time in Patent Office: 1,208 Days
• Field of Search: 33706-707, 337/00, 337/12, 33702-704, 337/58
• US Class Current: 33/707
• CPC Class Codes: B23Q 17/22 for indicating or measuring existing or desired position of tool or work B23Q16/005 takes precedence
• CPC Class Codes: G01D 5/34707 Scales; Discs, e.g. fixation, fabrication, compensation
• CPC Class Codes: G01D 5/34753 Carriages; Driving or coupling means

Abstract

A linear measuring device including a housing fastened to a first machine element and a scale within the housing, wherein the scale is fastened extending along the housing in a measuring direction. A scanning device for scanning a scale. A linear guide device including a guide rail, which is rigidly assigned to the housing; and a guide carriage, which is guided on the guide rail along the housing in the measuring direction, and includes a fastener to fasten the guide carriage rigidly on a second machine element. The housing is structured so that during measuring operations it is deflected perpendicular to the measuring direction, so that in the course of movement of the guide carriage in a direction perpendicular to the measuring direction the housing is taken along in the direction perpendicular to the measuring direction.

Claims

1. A linear measuring device for measuring a relative position of a first machine element with respect to a second machine element, comprising:

a housing fastened to said first machine element;

a scale within said housing, wherein said scale is fastened extending along said housing in a measuring direction;

a scanning device for scanning said scale;

a linear guide device comprising;

a guide rail, which is rigidly assigned to said housing and includes a guide area; and

a guide carriage, which supports said scanning device and is guided on said guide rail along said housing in said measuring direction, wherein said guide carriage is connected to said guide rail, free of play in all directions perpendicular to said measuring direction and said guide carriage comprises a fastener to fasten said guide carriage rigidly on said second machine element in said measuring direction and said all directions perpendicular to said measuring direction;

wherein said housing is structured so that during measuring operations it is deflected perpendicular to said measuring direction at least in said guide area, so that in the course of movement of said guide carriage in a direction perpendicular to said measuring direction said housing is taken along in said direction perpendicular to said measuring direction.

2. The linear measuring device in accordance with claim 1, wherein said guide rail is constituted by an exterior face of said housing.

3. The linear measuring device in accordance with claim 2, wherein said housing is tube-shaped and has a circular-cylindrical circumferential area defining said guide area of said guide rail, wherein said guide carriage is guided on said guide area, free of play and with a degree of freedom in said measuring direction, as well as with a rotary degree of freedom around a longitudinal axis of said housing.

4. The linear measuring device in accordance with claim 1, wherein said scanning device is rigidly connected with said guide carriage in said measuring direction and in said all directions perpendicular to said measuring direction.

5. The linear measuring device in accordance with claim 1, wherein said scale comprises a measuring structure, which can be photo-electrically scanned and wherein said scanning device comprises at least one light source and a light-sensitive detector.

6. The linear measuring device in accordance with claim 1, wherein said scale is arranged inside said housing, and wherein said scanning device comprises:

at least one light source; and

a light-sensitive detector outside of said housing for scanning said scale via a light beam through said housing, for which purpose said housing is transparent to said light beam at least in a circumferential scanning area.

7. The linear measuring device in accordance with claim 1, wherein said scale is fastened on an interior wall along said housing.

8. The linear measuring device in accordance with claim 7, wherein said scale is a linearly rigid steel tape of low flexural strength.

9. The linear measuring device in accordance with claim 1, wherein said housing is linearly rigid and has flexural strength.

10. The linear measuring device in accordance with claim 9, wherein said housing comprises a first mounting element with a first connector located at one end of said housing and a second mounting element with a second connector located at another end of said housing and wherein said first connector and said second connector hold said housing on said first and second mounting elements deflectable perpendicular to said measuring direction.

11. The linear measuring device in accordance with claim 10, wherein said first connector connects said housing so as to be linearly movable with respect to said first mounting element, and said second connector connects said housing rigidly in said measuring direction with respect to said second mounting element.

12. The linear measuring device in accordance with claim 1, wherein said housing is linearly rigid and has low flexural strength. which can be scanned by a transmitted light scanning process, such as represented in FIG. 3. In this case the scale 200 has again been fastened on the housing 3 via a support, or directly, and the scanning device 2 is placed protectively in the interior of the housing 3. On one side of the scale 200, the scanning device 2 has a light source 21, and on the other side of the scale 200 a light-sensitive detector 22. The housing 3 is slit, and this slit 23 is sealed by an elastic seal 24, through which protrudes a sword-shaped connector 25, which rigidly connects the scanning device 2 with the guide carriage 10 in all directions X, Y, Z.