Method for determining the position of a first moving component relative to a second component and device for applying said method

• US 7,842,913 B2
• Filed: 12/05/2008
• Issued: 11/30/2010
• Est. Priority Date: 12/23/2005
• Status: Expired due to Fees

• Current Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Inventors: Wright, C. David
• Primary Examiner(s): NGUYEN, SANG H
• Application Number:
  US12/315,705
• Publication Number:
  US 20090147271A1
• Time in Patent Office: 725 Days
• Field of Search: 356/614, 356/617, 356/620, 356402-408, 250/231.13, 250/231.11, 250/231.14, 250/227.11, 250/237.G
• US Class Current: 250/231.13
• CPC Class Codes: G01D 5/347 using displacement encoding scales

Abstract

A method for determining the position of one of two components in relative motion with respect to each other, using optical means, comprises:

• • directing at least one light beam emitted by a light source attached to one component towards a diffractive support attached to the second component, calculated and manufactured for generating an optical signal indicative of the positioning of said support, the optical signal being produced by the diffractive support in transmission and/or in reflection, and the optical signal including information indicative of its quality;
  • detecting and reading at least one optical code formed by said signal, which corresponds to a unique position of the diffractive support relatively to the beam; and
  • assigning a position to each detected optical code.

Claims

1. A device for measuring the position of a first component in relative motion with respect to a second component, said device comprising:

at least one diffractive support including

mounting means carried by a first component in relative motion with respect to a second component, and

at least one diffractive track;

at least one fixed light source, emitting at least one light beam onto said at least one diffractive support;

means for detecting and reading an optical signal obtained by diffraction of the light beam(s) by transmission or reflection from the diffractive support(s), wherein said optical signal contains information indicative of its quality; and

means for processing optical code resulting from the detected signal allowing the position of the diffractive support(s) relatively to the beam(s) and the reliability of the position information to be determined,

wherein said diffractive track has means diffracting the light beam emitted by said at least one light source fixed relatively to the second component, and

wherein said diffractive track contains information indicative of its quality.

2. The measuring device according to claim 1, further comprising means for assessing the reliability of the position information.

3. The measuring device according to claim 1, further comprising means for correcting the position information.

4. The measuring device according to claim 3, wherein the coherent light source is a laser diode.

5. The measuring device according to claim 1, wherein the light beam is sent towards the diffractive support via at least one optical relay component of the lens, prism, diffractive component, reflective component, refractive component type and/or via at least one optical guiding component of the optical fiber or waveguide type.

6. The measuring device according to claim 1, wherein the beam is towards the diffractive support via at least one unit exerting a collimation, focusing or astigmatism function.

7. The measuring device according to claim 1, wherein the light beam is towards the diffractive support via at least one conformation diaphragm.

8. The measuring device according to claim 1, wherein the means for detecting and reading diffracted optical codes consist of photodetectors of the type, array strips or pixel matrices, CCD sensors, photodiodes, or even photoelectric or photovoltaic cells positioned on the trajectory of the rays diffracted by the diffractive support.

9. The measuring device according to claim 8, wherein the photodetectors are positioned so that each diffracted optical structure obtained at the location where a diffracted ray encounters a pixel array, covers at least 3 pixels.

10. The measuring device according to claim 8, wherein the number of pixels between two adjacent spots is set to at least 3 pixels.

11. The measuring device according to claim 1, wherein the light beam is directed at an incidence normal to the diffractive support.

12. The measuring device according to claim 1, wherein the light ray is tilted towards the diffractive support, by an angle between 0°

and 17°

, relatively to the normal to the diffractive support.

13. The measuring device according to claim 1, further comprising synchronization means for detecting and reading an optical code generated by an individualized diffractive structure when the beam emitted by the light source is centered on said structure.

14. The measuring device according to claim 13, characterized in that the synchronization means include specific photodetectors dedicated to detecting optical structures obtained independently of those forming the code of the position to be measured positioned on at least one diffractive track specifically dedicated to synchronization.

15. The measuring device according to claim 1, wherein the device is configured to facilitate measurement of the rotary movement applied to at least one diffractive support permanently attached to a rotary shaft.

16. The measuring device according to claim 15, comprising two superimposed diffractive rotary disks, one including the measurement of angular positions on one revolution and the other, rotating N times less rapidly, allowing the number of accomplished revolutions to be measured within the limit of N revolutions.

17. The measuring device according to claim 1, wherein a single component forming an optical guide simultaneously acts as a diaphragm, a collimating lens, mirror(s), a protective housing for the laser diode and the photodetectors.

18. A device for determining the position of one of two components in relative motion, with respect to each other, said device comprising:

a light source attached to one of said components and configured to emit at least one light beam therefrom;

a diffractive support attached to the other component, said diffractive support operative to generate an optical signal indicative of the relative position of said support in response to said at least one light beam impinging thereon,

wherein the optical signal is generated by the diffractive support in transmission and/or in reflection, and wherein the optical signal includes information indicative of its quality;

processing means operative to detect and read at least one optical code formed by said signal, which corresponds to a unique position of the diffractive support relative to the beam, and which code includes information indicative of the quality of the signal, said processing means operative to

assess the quality of the signal,

assign a position to each detected optical code, and

generate and transmit an output signal indicative of said position to a user,

wherein each detected and read optical code is compared with electronic codes stored in a memory table for determining the position of the diffractive support, and

wherein each optical code corresponding to a position of the diffractive support includes at least one optical synchronization structure, the detection of which allowing the triggering of the reading phase of the optical signal integrating the code of a position of the diffractive support relatively to the beam.