Optical translation measurement

• US 20030142288A1
• Filed: 07/19/2002
• Published: 07/31/2003
• Est. Priority Date: 03/09/1998
• Status: Active Grant

• Current Assignee: OTM Technologies Ltd.
• Original Assignee: OTM Technologies Ltd.
• Inventors: Kinrot, Uri, Kinrot, Opher, Lederer, Gilad
• Granted Patent: US 6,741,335 B2
• Time in Patent Office: Days
• US Class Current: 356/28
• CPC Class Codes: G01D 5/347 using displacement encoding scales
• CPC Class Codes: G01P 3/366 by using diffraction of light for measuring speed of fluids G01P5/26
• CPC Class Codes: G01P 3/806 in devices of the type to be classified in G01P3/68
• CPC Class Codes: G01S 17/50 Systems of measurement based on relative movement of target
• CPC Class Codes: G01S 7/4811 common to transmitter and receiver
• CPC Class Codes: G06F 3/0312 for tracking the rotation of a spherical or circular member, e.g. optical rotary encoders used in mice or trackballs using a tracking ball or in mouse scroll wheels tracking relative movement in co-operation with a regularly or irregularly patterned surface, e.g. as in optical mice G06F3/0317; constructional details of scroll or thumb-wheels G06F3/0362; optical rotary encoders G01D5/3473

Abstract

A method for determining the relative motion of a surface with respect to a measurement device comprising:

illuminating the surface with incident illumination;

detecting illumination reflected from the surface to form at least one detected signal; and

determining the amount of relative motion parallel to the surface from said at least one detected signal,

characterized in that

said determining includes correcting for the effects of relative motion perpendicular to the surface.

Claims

1. A method for determining the relative motion of a surface with respect to a measurement device comprising:

placing a partially transmitting object, which is part of the measuring device, adjacent to the surface;

illuminating the surface with incident illumination, which does not constitute an interference pattern, such that the illumination is reflected from portions of the surface, wherein at least part of at least one of the incident and reflected illumination passes through the object;

detecting the illumination reflected from the surface, and generating a detected signal; and

determining the relative motion of the surface parallel to the surface, from the detected signal.

2. A method according to claim 1 and comprising:

varying the phase between illumination reflected from or diffracted by the object and at least a portion of the illumination reflected from the surface.

3. A method according to claim 2 wherein the direction is determined based on said varied phase.

4. A method according to claim 1 and including determining motion in a direction perpendicular to the surface.

5. A method according to claim 1 wherein varying the phase comprises periodically varying the phase.

6. A method according to claim 5, wherein determining the direction of relative motion comprises determining the direction of relative motion based on a characteristic of the signal caused by said periodically varying relative phase.

7. A method according to claim 2 wherein varying the phase comprises:

causing the object to move periodically substantially in the direction of the motion being measured.

8. A method according to claim 2 wherein varying the phase comprises:

causing the object to move periodically substantially perpendicularly to the direction of the motion being measured.

9. A method according to claim 2 wherein varying the phase comprises:

providing a transparent material between the object and the surface; and

electrifying the material such that its optical length in the direction of the illumination varies.

10. A method according to claim 9 wherein the transparent material is a piezoelectric material.

11. A method according to claim 1 and including determining both the magnitude and direction of the translation utilizing a single detector.

12. A method according to claim 2, wherein varying the phase comprises, introducing a static phase change and wherein determining the direction of relative motion comprises determining the direction of relative motion based on a characteristic of the signal caused by said phase change.

13. A method according to claim 2 and including:

dividing at least part of the illumination that is reflected from the surface into at least a first illumination having a first phase and a second illumination having a second phase.

14. A method according to claim 13 wherein said first and second illuminations have different polarizations.

15. A method according to claim 14 wherein dividing comprises passing the illumination incident on the surface through a birefringent material.

16. A method according to claim 14 and including passing the illumination reflected from the surface through a birefringent material.

17. A method according to claim 15 and including placing the birefringent material between the object and the surface.

18. A method according to claim 1 and including determining the magnitude and direction of the translation utilizing two detectors which produce different detected signals depending on the direction of the translation.

19. A method according to claim 18 and including determining the direction of translation from the sign of a phase difference between the different detected signals.

20. A method according claim 1 wherein the illumination is perpendicularly incident on the surface.

21. A method according to claim 1 and including determining the direction of motion.

22. A method according to claim 1 wherein determining the motion comprises determining variations in the amplitude of the signal with position.

23. A method according to claim 22 wherein the motion is determined from zero crossings of the detected signal.

24. A method according to claim 1 wherein the surface is an optically diffusely reflecting surface.

25. A method according to claim 1 wherein the surface has no markings indicating position.

26. A method according to claim 1 wherein the illumination comprises visible illumination.

27. A method according to claim 1 wherein the illumination comprises infra-red illumination.

28. A method according to claim 1 and including detecting relative motion of the surface in two directions parallel to the surface.

29. An optical mouse comprising:

a housing having an aperture facing a surface; and

an optical motion detector which views the surface through the aperture, wherein the optical motion detector utilizes the method of claim 1 to determine the translation of the housing with respect to the surface.

30. A touch point device for use as a control device, comprising:

a housing having an aperture; and

an optical detector which determines the motion of a finger which is translated across the aperture wherein the optical detector utilizes the method of any of claim 1 to determine the translation.

32. A combination mouse/touch point according to claim 31 wherein the optical detector utilizes the method of claim 28 to determine the translation.

33. An encoder comprising:

an optically diffusely reflecting surface having no markings other than reference markings; and

an optical detector having relative motion with respect to the surface, wherein the optical detector measures relative motion with respect to the surface relative to the reference markings, wherein the optical detector utilizes the method of claim 1.

34. An encoder according to claim 33 wherein the surface is the surface of a disk which rotates about an axis and wherein the detector measures the rotation of the disk.

35. A virtual pen comprising:

an optical detector which is adapted to measure relative motion with respect to an optically diffuse surface utilizing the method of claim 1;

and

circuitry which translates said measured relative motion into written or graphical data.

31. A combination mouse/touch point for use as a pointer for a computer comprising:

a housing having an aperture;

an optical detector which determines the motion of an object which is translated across the aperture; and

means for determining whether the aperture is upward or downward facing.