Optical displacement detection over varied surfaces

• US 20070008286A1
• Filed: 06/20/2006
• Published: 01/11/2007
• Est. Priority Date: 06/30/2005
• Status: Active Grant

• Current Assignee: Logitech Europe S A (Logitech International SA)
• Original Assignee: Logitech Europe S A (Logitech International SA)
• Inventors: Chauvin, Nicolas, Theytaz, Olivier, Sasselli, Nicolas, Karamata, Boris
• Granted Patent: US 7,898,524 B2
• Time in Patent Office: Days
• US Class Current: 345/166
• CPC Class Codes: G06F 3/0317 in co-operation with a patterned surface, e.g. absolute position or relative movement detection for an optical mouse or pen positioned with respect to a coded surface
• CPC Class Codes: G06F 3/03543 Mice or pucks G06F3/03541 takes precedence

Abstract

Embodiments of the present invention enable an optical device to track on a diffusing surface over which a transparent and/or translucent and/or optically smooth surface is placed. Some embodiments are directed towards detecting when an optical device is lifted off the surface it was resting on. Embodiments also include a sensing system that detects the z distance (distance to the tracking surface) and improves image quality by improving the effectiveness of the optical sensor subsystem and/or the illumination subsystem at the detected z distance. Other embodiments include a system and method that enables an optical device to track on a transparent and/or translucent and/or optically smooth surface alone. This may involve dark-field imaging based on certain features (e.g., dirt) already present on the transparent surface. Alternately, this may involve creating features such as droplets, spreading dirt residue, and creating thermal spots, which can be used for tracking.

Claims

1. A method of determining the distance between an optical displacement detection system and a diffusing surface below a layer of material that passes at least some light through the layer, the layer having a top surface and a bottom surface, the method comprising:

receiving light reflected from the top surface of the layer at a first portion of a detector;

receiving light reflected from the bottom surface of the layer at a second portion of the detector;

receiving light from the diffusing surface at a third portion of the detector;

determining the distance between an optical displacement detection system and the diffusing surface by determining the distance between at least one of the first, second, and third portions of the detector.

2. The method of claim 1, wherein the detector is one of a group consisting of a CCD line and a position sensitive detector.

3. The method of claim 1, wherein the step of determining the distance comprises using triangulation techniques.

4. An optical displacement detection system for imaging a diffusing surface below a reflecting layer, the system comprising:

an illumination module for illuminating the diffusing surface;

a sensor module for receiving light from the diffusing surface;

a plurality of apertures, each of the plurality of apertures being positionable in between the sensor module and the received light, wherein each of the plurality of apertures is optimized for optical displacement detection for a particular range of distances between the optical displacement detection system and the diffusing surface.

5. A lift detection module for use in an optical displacement detection device, the lift detection module comprising:

a light source for creating an illumination spot on a surface; and

a detector for detecting light received from the illumination spot on the surface, wherein it is determined that the optical displacement detection device is lifted if the detector does not detect any light.

6. The lift detection module of claim 5, wherein the light source is a collimated light source.

7. A method for detecting when an optical displacement detection device is lifted from a surface, the method comprising:

illuminating a spot on the surface;

determining whether a detector receives light from the illuminated spot;

in response to determining that the detector receives light from the illuminated spot, concluding that the optical displacement detection device is not lifted; and

in response to determining that the detector does not receive light from the illuminated spot, concluding that the optical displacement detection device is lifted.

8. An optical displacement detection system capable of imaging a diffusing surface below a transparent layer, the system comprising:

an illumination subsystem;

a sensor subsystem, wherein the sensor subsystem is configured to image a diffusing surface below a transparent layer.

9. The optical displacement detection system of claim 8, wherein the sensor subsystem comprises a telecentric imaging system.

10. The optical displacement detection system of claim 8, wherein the sensor subsystem comprises a variable aperture.

11. The optical displacement detection system of claim 8, wherein the sensor subsystem comprises:

a plurality of sensors, wherein each sensor is optimized for a particular range of distances of the optical displacement detection system from the diffusing surface; and

a controller for selecting an appropriate one of the plurality of sensors, in response to a determination of the distance of the optical displacement detection system from the diffusing surface.

12. The optical displacement detection system of claim 8, wherein the sensor subsystem has autofocusing capabilities.

13. The optical displacement detection system of claim 8, wherein the sensor subsystem comprises a variable shape lens.

14. The optical displacement detection system of claim 8, wherein the illumination subsystem comprises a light source that receives a variable amount of current, wherein the amount of current depends on the distance of the optical displacement detection system from the diffusing surface.

15. The optical displacement detection system of claim 8, wherein the illumination subsystem comprises:

a plurality of light sources, wherein each light source is optimized for a particular range of distances of the optical displacement detection system from the diffusing surface; and

a controller for selecting an appropriate one of the plurality of light sources, in response to a determination of the distance of the optical displacement detection system from the diffusing surface.

16. A method of determining the distance between an optical displacement detection system and a diffusing surface below a layer of material that passes at least some light through the layer, the method comprising:

illuminating a portion of the diffusing surface with a slightly diverging light beam;

determining the size of the illuminated portion of the diffusing surface; and

correlating the size of the illuminated portion of the diffusing surface with the distance between the optical displacement detection system and the diffusing surface.

17. A dark-field optical displacement detection system of an optical input device capable of tracking on a surface of a layer of a material that passes at least some light through the layer, the surface having certain features thereon, the system comprising:

a light source for illuminating the surface;

a lens positioned to receive at least some diffracted light from the certain features on the surface but not the zero order light reflected from the surface; and

a detector optically coupled to the lens that receives the at least some diffracted light.

18. The dark-field optical system of claim 17, wherein the system further comprises an imaging subsystem that spatially under-samples the image.

19. The dark-field optical system of claim 17, wherein the system further comprises an illumination subsystem comprising N spatially incoherent light sources to provide a non-uniform radial illumination.

20. The dark-field optical system of claim 17, wherein the system further comprises an illumination subsystem comprising a laser diode and a diffractive optical element to provide a uniform radial illumination.

21. The dark-field optical system of claim 17, wherein the system comprises an illumination subsystem comprising a diffractive optical element and a spherical mirror to provide a uniform radial illumination.

22. The dark-field optical system of claim 17, wherein the certain features are dirt residue, and wherein the system further comprises a dirt spreader in contact with the surface.

23. The dark-field optical system of claim 22, wherein a material of the dirt spreader is one of a group consisting of foam, polymer, micro airbrush, and Teflon skater.

24. The dark-field optical system of claim 17, wherein the certain features are droplets of a liquid.

25. An optical displacement detection system of an optical input device comprising an interferometric detection system capable of tracking on a surface of a layer of material that passes at least some light through the layer, the interferometric detection system comprising:

a light source;

a beamsplitter for splitting light from the light source into a first portion of light and a second portion of light, the first portion of light directed to a detector, the second portion of light directed to a tracking surface;

a detector for detecting an interferometric signal comprised of the first portion of light and Rayleigh backscattered light from the tracking surface.

26. The optical displacement detection system of claim 25, wherein the light source is collimated.

27. The optical displacement detection system of claim 25, wherein the light source is polarized.

28. The optical displacement detection system of claim 25, further comprising a grating located between the Rayleigh backscattered light and the detector for causing the Rayleigh backscattered light to propagate in the same direction as the first portion of light between the grating and the detector.

29. An optical displacement detection system of an optical input device capable of tracking on a surface of a layer of material that passes at least some light through the layer, the system comprising:

a light source for illuminating the surface;

a storage module for storing a liquid;

an ejection system coupled to the storage module for ejecting droplets of the liquid on to the surface;

a lens positioned to receive at least some light from the droplets of liquid on the surface; and

a detector optically coupled to the lens to receive the at least some light.

30. The optical displacement detection system of claim 29, wherein the liquid is water.

31. An optical displacement detection device for tracking on varied surfaces, the system comprising:

a dark-field imaging module for optical displacement detection on a first surface of a layer of a material that passes at least some light through the layer, the first surface having certain features thereon, the dark-field imaging subsystem comprising;

a first light source for illuminating the first surface;

a first lens positioned to receive at least some diffracted light from the certain features on the first surface but not the zero order light reflected from the first surface;

a first detector optically coupled to the first lens that receives the at least some diffracted light; and

a conventional imaging module for optical displacement detection on a second surface of an optically rough material, the conventional imaging subsystem comprising;

a second light source for illuminating the second surface;

a second lens positioned to receive at least some light from the second surface; and

a second detector optically coupled to the second lens that at least some light.

32. The optical displacement detection device of claim 31, further comprising:

a lift detection module for detecting when the optical detection device is not in contact with the first surface.

33. A method for tracking on a surface of a layer of a material that passes at least some light through the layer, the method comprising:

creating a hot spot on the surface with a focused laser beam;

detecting the hot spot on a sensor; and

creating a new hot spot is when a trigger condition is met.

34. The method of claim 33, wherein the trigger condition is that the hot spot is about to fall outside a field of view of the sensor.

35. The method of claim 33, wherein the trigger condition is that a temperature of the hot spot falls below a predefined detection threshold relative to an ambient temperature.

36. The method of claim 33, wherein the sensor comprises an IR detector array.