Speckle navigation system

• US 20070139381A1
• Filed: 12/20/2005
• Published: 06/21/2007
• Est. Priority Date: 12/20/2005
• Status: Active Grant

• Current Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Original Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Inventors: Sanders, Steven, Trisnadi, Jahja, Carlisle, Clinton, Spurlock, Brett
• Granted Patent: US 7,737,948 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

Abstract

One embodiment relates to a laser positioning device for sensing relative movement between a data input device and a surface by determining displacement of image features in a succession of images of the surface. The device forms a single integrated package, which includes a planar substrate and a transparent encapsulant that also embodies a collimating lens. Both a coherent light source and a sensor array and associated circuitry are configured on the planar substrate. Another embodiment relates to a method of sensing relative movement between a data input device and a surface. Coherent light is emitted from a laser and collimated so as to form a collimated illumination beam with a predetermined diameter, D, and a substantially uniform phase front. A speckle pattern is generated by impingement of the collimated illumination beam on the surface and detected by a sensor array. Other embodiments are also disclosed.

Claims

1. A laser positioning device for sensing relative movement between a data input device and a surface by determining displacement of optical speckle in a succession of images of the surface, the device comprising:

a planar substrate;

a coherent light source configured on the planar substrate;

a sensor array and associated circuitry configured on the planar substrate; and

a collimating lens positioned between the coherent light source and the surface.

2. The laser positioning device of claim 1, wherein the collimating lens is embodied as one of the following:

a) part of a transparent encapsulant which covers the planar substrate;

b) part of a molded transparent plastic which covers the planar substrate;

or c) a small lens that is plugged into a package covering the planar substrate.

3. The laser positioning device of claim 1, further comprising an opaque edge for lift detection.

4. The laser positioning device of claim 3, wherein the edge is placed so as to block an illuminated portion of the planar substrate from a field of view of the sensor array if the device is lifted by more than a predetermined height above the planar substrate.

5. The laser positioning device according to claim 1, wherein the collimating lens is configured to receive coherent light from the coherent light source and to provide a collimated illumination beam which is transmitted to the surface at or near a normal angle to the surface.

6. The laser positioning device according to claim 5, wherein, due to uniformity of a phase front of the collimated beam, a small lateral displacement between the planar substrate and the surface results in a shift of a speckle pattern with minimal boiling.

7. The laser positioning device according to claim 1, wherein the sensor array comprises a two-dimensional comb array.

8. The laser positioning device according to claim 7, wherein the comb array receives light forming an image of the surface without use of a collection lens.

9. The laser positioning device according to claim 8, wherein the predetermined diameter, D, of the collimated illumination beam satisfies an equation D=(hλ

)/(ξ

Λ

cos²θ

), wherein h is a height from the planar substrate to the surface, λ

is a wavelength of the coherent light, ξ

is a fraction between 0.25 and 0.5, Λ

is a period of the comb array, and θ

is an angle subtended by the beam from a point on the sensor.

10. The laser positioning device according to claim 9, wherein, due to the predetermined diameter of the collimated beam, a speckle size at the surface matches a period of the comb array.

11. A method of sensing relative movement between a data input device and a surface by determining displacement of optical features in a succession of images of the surface, the method comprising:

emitting coherent light from a laser;

collimating the coherent light so as to form a collimated illumination beam with a predetermined diameter, D, and is transmitted to the surface at a normal angle thereto;

generating a speckle pattern by impingement of the coherent light from the collimated illumination beam on the surface; and

detecting the images of the surface using a sensor array.

12. The method according to claim 11, further comprising use of an opaque edge for lift detection.

13. The method according to claim 11, wherein, due to a substantially uniform phase front of the collimated beam, a small lateral displacement between the planar substrate and the surface results in a shift of a speckle pattern.

14. The method according to claim 11, wherein the sensor array comprises a comb array.

15. The method according to claim 14, wherein the comb array directly images the surface without use of an imaging or a collection lens therebetween.

16. The method according to claim 14, wherein the laser and the sensor array are both configured on a same planar substrate that is configured to lie parallel to the surface.

17. The method according to claim 16, wherein the predetermined diameter, D, of the collimated illumination beam satisfies an equation D=(h λ

)/(ξ

Λ

cos²θ

), wherein h is a height from the planar substrate to the surface, λ

is a wavelength of the coherent light, ξ

is a fraction between 0.25 and 0.5, Λ

is a period of the comb array, and θ

is an angle subtended by the beam from a point on the sensor.

18. The method according to claim 14, wherein, due to the predetermined diameter of the collimated beam, a speckle size at the surface matches a period of the comb array.

19. A speckle navigation system comprising:

means for emitting coherent light;

means for collimating the coherent light so as to form a collimated illumination beam with a predetermined diameter, D, which is transmitted to a surface at a normal angle thereto;

means for generating a speckle pattern by impingement of the coherent light from the collimated illumination beam on the surface; and

means for detecting an image of the surface using a sensor array.

20. The system according to claim 19, further comprising use of an opaque edge for lift detection.