Optical displacement detection over varied surfaces

• US 20070013661A1
• Filed: 09/18/2006
• Published: 01/18/2007
• 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, Mathis, Olivier, Karamata, Boris
• Granted Patent: US 7,872,639 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 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 with an illumination beam, the illumination beam having an optical axis;

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

a detector optically coupled to the lens that receives the at least some diffracted light, wherein the detector has a second optical axis.

2. The dark-field optical system of claim 1, wherein an angle formed by the optical axis and a line formed by a first end of the aperture and the intersection of the second optical axis with the surface, is less than 15 degrees.

3. The dark-field optical system of claim 2, wherein the angle is less than 12 degrees.

4. The dark-field optical system of claim 2, wherein the angle is less than 7 degrees.

5. The dark-field optical system of claim 1, wherein the optical device is a mouse.

6. The dark-field optical system of claim 1, further comprising:

a diffractive optical element to control the illumination beam.

7. The dark-field optical system of claim 1, wherein the diffractive optical element is designed to provide a step intensity profile along a plane of the aperture.

8. 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 plurality of light sources for illuminating the surface;

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

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

9. The dark-field optical displacement detection system of claim 8, wherein a second of the plurality of light sources is turned on in response to the determination that the detector cannot detect a sufficient number of features on the surface for calculating optical displacement with a first of the plurality of light sources illuminating the surface.

10. The dark-field optical displacement detection system of claim 9, wherein the first light source is turned off when the second light source is turned on.

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

illuminating the surface with a first light source;

determining whether a sufficient number of features are detected on the surface to enable calculation of displacement of the optical input device when the surface is illuminated with the first light source;

in response to the determination that a sufficient number of features are not detected, illuminating the surface with a second light source;

calculating displacement of the optical input device based on the detected features.

12. The method of claim 11, further comprising:

determining whether a sufficient number of features are detected on the surface to enable calculation of displacement of the optical input device when the surface is illuminated with the second light source;

in response to the determination that a sufficient number of features are not detected, illuminating the surface with a third light source.

13. The method of claim 11, further comprising:

turning off the first light source in response to the determination that a sufficient number of features are not detected.