Granted Patent B2

US 9,104,268 · App. 13/020,742 · Granted Aug 11, 2015

Abstract

Claims (40)

1. An optical finger navigation device comprising:

a navigation cover which comprises a tracking surface and an illumination surface, wherein the tracking surface exhibits a first light reflection characteristic in a presence of a navigation object at the tracking surface and a second light reflection characteristic in an absence of the navigation object at the tracking surface;

a light source to generate illumination directed toward the illumination surface of the navigation cover; and

a first redirection structure interposed between the light source and the illumination surface of the navigation cover, wherein a reflection surface of the first redirection structure is approximately facing the illumination surface of the navigation cover, and an illumination surface of the first redirection structure is approximately facing the light source, wherein the first redirection structure defines at least one hole there through to pass light generated by the light source toward the illumination surface of the navigation cover;

a second redirection structure located within a path of the light reflected by the reflection surface of the first redirection structure, wherein the second redirection structure comprises a reflection surface to redirect the light from the direction that is approximately parallel to the tracking surface; and

an image sensor to receive the light reflected from the reflection surface of the second redirection structure, wherein the image sensor is approximately parallel to the navigation cover.

2. The optical finger navigation device of claim 1 , wherein the reflection surface of the first redirection structure is configured to redirect light reflected from the tracking surface a direction that is approximately parallel to the tracking surface.

3. The optical finger navigation device of claim 2 , further comprising an optical lens interposed between the first and second redirection structures, wherein the optical lens is configured to influence a path of the light reflected from the reflection surface of the first redirection structure towards the reflection surface of the second redirection structure.

4. The optical finger navigation device of claim 2 , further comprising an aperture stop interposed between the first and second redirection structures, wherein the aperture stop is configured to block at least some of the light reflected from the reflection surface of the first redirection structure towards the reflection surface of the second redirection structure

5. The optical finger navigation device of claim 2 , further comprising a processing device coupled to the image sensor, wherein the processing device is configured to perform post processing on an image signal from the image sensor to substantially remove a shadowing effect within the image signal due to a shadow within an illumination pattern of the light at the tracking surface, wherein the shadow results from a contrast between the light from the light source which passes through the hole in the first redirection surface and the light from the light source which is blocked by the first redirection surface.

6. The optical finger navigation device of claim 5 , wherein the processing device is further configured to perform spatial filtering on a frame of pixel data from the image sensor to substantially remove the shadowing effect within the frame of pixel data due to the shadow within the illumination pattern of the light at the tracking surface.

7. The optical finger navigation device of claim 5 , wherein the processing device is configured to equalize a constant intensity distribution over plurality of frames of pixel data from the image sensor to substantially remove the shadowing effect within the frame of pixel data due to the shadow within the illumination pattern of the light at the tracking surface.

8. The optical finger navigation device of claim 2 , wherein the hole through the first redirection surface has an effective width, approximately parallel to the tracking surface, of between about 10 micrometers and 200 micrometers.

9. The optical finger navigation device of claim 1 , further comprising an optical element disposed approximately within an optical path of the light from the light source through the hole in the first redirection structure, wherein the optical element is configured to diffuse the light from the light source before the light is incident on the illumination surface of the first redirection structure.

10. The optical finger navigation device of claim 1 , wherein the first redirection structure comprises:

a plastic molded piece with the hole defined therethrough; and

a metallization layer disposed on at the reflection surface to form a mirror at the reflection surface of the first redirection structure.

11. The optical finger navigation device of claim 10 , wherein the metallization layer is deposited at the reflection surface of the first redirection structure to cover only portions within an application field of view from an application direction, and an interior surface of the hole through the first redirection structure is substantially free from the metallization layer.

12. A method for operating an optical finger navigation device, the method comprising:

generating light at a light source;

passing a portion of the light from the light source through a hole in a first redirection structure to illuminate a tracking surface of a navigation cover, wherein the tracking surface exhibits a first light reflection characteristic in a presence of a navigation object at the tracking surface and a second light reflection characteristic in an absence of the navigation object at the tracking surface; and

reflecting light from the tracking surface back toward a reflection surface of the first redirection structure, wherein the reflection surface of the first redirection structure approximately faces the illumination surface of the navigation cover;

redirecting the light from the reflection surface of the first redirection structure at a reflection surface of a second redirection structure, wherein the reflection surface of the second redirection structure redirects the light toward an image sensor, wherein the image sensor is approximately parallel with the tracking surface of the navigation cover.

13. The method of claim 12 , further comprising redirecting the light at the reflection surface of the first redirection structure in a direction that is approximately parallel to the tracking surface.

14. The method of claim 13 , further comprising:

generating an image signal at the image sensor, wherein the image signal is representative of a plurality of pixel values within an image frame;

sending the image signal to a processing device; and

spatially filtering the image signal to substantially remove a shadowing effect within the pixel values of the image frame.

15. The method of claim 13 , further comprising:

generating an image signal at the image sensor, wherein the image signal is representative of a plurality of pixel values within a plurality of image frames;

sending the image signal to a processing device; and

processing the image signal to equalize a constant intensity distribution of the image frames to substantially remove a shadowing effect within the pixel values of the image frames.

16. The method of claim 12 , further comprising diffusing the light from the light source at approximately an optical element disposed within an optical path of the light from the light source through the hole in the first redirection structure.

17. The method of claim 12 , further comprising an optical lens interposed between the first and second redirection structures, wherein the optical lens is configured to influence a path of the light reflected from the reflection surface of the first redirection structure towards the reflection surface of the second redirection structure.

18. The method of claim 12 , further comprising an aperture stop interposed between the first and second redirection structures, wherein the aperture stop is configured to block at least some of the light reflected from the reflection surface of the first redirection structure towards the reflection surface of the second redirection structure.

19. An optical device comprising:

a navigation cover which comprises a tracking surface and an illumination surface, wherein the tracking surface exhibits a first light reflection characteristic in a presence of a navigation object at the tracking surface and a second light reflection characteristic in an absence of the navigation object at the tracking surface;

a light source to generate illumination directed toward the illumination surface of the navigation cover; and

a first redirection structure interposed between the light source and the illumination surface of the navigation cover, wherein a reflection surface of the first redirection structure is approximately facing the illumination surface of the navigation cover, and an illumination surface of the first redirection structure is approximately facing the light source, wherein the first redirection structure defines at least one transparent section to pass light generated by the light source toward the illumination surface of the navigation cover, and wherein the first redirection structure further comprises a non-planar feature on the reflection surface, wherein the transparent section is on a face of the non-planar feature.

20. The optical device of claim 19 , further comprising an optical lens interposed between the first and second redirection structures, wherein the optical lens is configured to influence a path of the light reflected from the reflection surface of the first redirection structure towards the reflection surface of the second redirection structure.

Assignments (8)