Electro-optical measuring device for determining the relative position of two bodies, or of two surface areas of bodies, in relation to each other

• US 6,040,903 A
• Filed: 09/22/1998
• Issued: 03/21/2000
• Est. Priority Date: 01/22/1997
• Status: Expired due to Term

• Current Assignee: PRÜFTECHNIK Dieter Busch AG (Fortive Corp.)
• Original Assignee: PRÜFTECHNIK Dieter Busch AG (Fortive Corp.)
• Inventors: Aschenbrenner, Kal, Letze, Thomas, Lysen, Heinrich
• Primary Examiner(s): Font, Frank G.
• Assistant Examiner(s): Smith, Zandra V.
• Application Number:
  US09/142,174
• Time in Patent Office: 546 Days
• Field of Search: 356/139.01, 356/399, 356/148, 356/375, 356/372, 356/152.2, 356/152.3, 356/153, 356/400, 250/206.1, 250/206.2, 250/231.13, 250/231.14, 250/231.18, 250/559.37, 33/286, 33/613, 33/645, 33/529
• US Class Current: 356/153
• CPC Class Codes: G01B 11/272 using photoelectric detection means

Abstract

Proposed for detecting the relative position of two bodies (2, 3) or surface regions of bodies is an electro-optical measuring instrument which has, in a known way, a light beam transmitter (4), which can be attached to the one body (3) or surface region and transmits a focused light beam (L), and a single-axis or multi-axis optoelectronic position detector with a light-sensitive measuring surface (5). During measurement of the bodies (2, 3) or surface regions, the light beam (L) impinges on the measuring surface (5), and its point of impingement (LA) moves over the light-sensitive surface (5), during execution of a measuring movement, in a way which is characteristic of the current mutual alignment of the bodies (2, 3) or surface regions. If the mutual alignment deviates substantially from a desired position, it can happen with the known measuring instruments of this type that without a correcting countermeasure the point of impingement (LA) of the light beam would leave the measuring surface (5) in the further course of the measuring movement. This is prevented in accordance with the invention by means of a device which carries out an extension of the measuring region while monitoring the measuring movement.

Claims

1. Electro-optical measuring instrument for detecting the relative position assumed by at least surface regions of two bodies with respect to one another, having a measuring arrangement which has at least one light beam transmitter and at least one optoelectronic position detector with a light-sensitive measuring surfaces wherein:

a) the light beam transmitter is arranged in a path fixed with respect to at least the surface region at least one of the two bodies in a manner for directing a focused light beam of small divergence onto the light-sensitive measuring surface of the position detector, and the position detector supplying electric signals corresponding to coordinates of the instantaneous point of impingement of the light beam on the measuring surface in response to impingement of said light beam thereon, and

b) at least parts of the measuring arrangement are configured to be displaceable in a defined measuring movement with the surface region of one of the two bodies in such a way that a geometrical locus, produced in the course of the measuring movement, of the points of impingement of the light beam on the measuring surface is in a predetermined relationship to the relative position of the at least surface regions of the two bodies to be determined, the measuring instrument having means for calculating, under programmed control, the relative position to be detected on the basis of the electric signals as supplied by the position detector during the measuring movement and further comprising a device which carries an extension of the measuring region while monitoring the measuring movement.

2. Electro-optical measuring instrument according to claim 1, further comprising a program controller set up such that the measuring instrument automatically treats changes in the position of the point of impingement of the light beam on the measuring surface, which take place without simultaneous measuring movement, as a displacement undertaken to extend the measuring region of the light beam with respect to the measuring surface of the position detector instead of as measuring signals.

3. Electro-optical measuring instrument according to claim 1, further comprising a device for generating a warning signal perceptible to the user when, in the course of the measuring movement, the point of impingement of the light beam has come within a predetermined distance of an edge of the measuring region.

4. Electro-optical measuring instrument according to claim 2, further comprising a device which indicates at which starting point on the measuring surface the point of impingement of the light beam is to be moved by changing the mutual position of the light beam and detector measuring surface for a following measuring region as soon as the point of impingement of the light beam a preceding measuring region has reached a still permissible end position at a boundary of the measuring surface and would run out of the measuring surface in the event of continuation of the measuring movement for detecting the state of alignment of two shafts arranged one behind another in an essentially coaxial fashion in which the measuring movement comprises rotation of the shafts about longitudinal axes thereof synchronously with pivoting of at least parts of the measuring arrangement mounted thereon about the stationary shafts in a fashion coaxial with their central axes.

5. Electro-optical measuring instrument according to claim 4, further comprising means for calculating a starting point such that an optimum length is available on the measuring surface for the geometrical locus of the points of impingement of the light beam to be expected in the following measuring region.

6. Electro-optical measuring instrument according to claim 4, wherein the program controller is configured such that the geometrical locus, produced during a rotation of the shafts by 360°

, of the points of impingement of the light beam can be calculated approximately from the geometrical locus, produced during a substantially smaller angle of rotation, of the points of impingement of the light beam.

7. Electro-optical measuring instrument according to claim 1 wherein for measuring the surface of a body, the light beam transmitter transmits a light beam extending as a reference beam on the surface, and the position detector with its measuring surface being fastened, for the purpose of measuring a distance of points on the surface from the reference beam, to a sensing element which is displaceable along the surface, and wherein a device is provided which detects whether, before each distance measured, for a measuring point on the surface, the spatial coordinates of this measuring point with respect to a spatially fixed reference point have been input into the measuring instrument, and wherein changes in the position of the point of impingement of the light beam on the measuring surface are automatically treated by the measuring instrument as an extension of the measuring region when this change is not accompanied by a preceding input of spatial coordinates.