Offset illumination aperture for optical navigation input device
View Patent ↗An optical navigation input device with an offset imaging aperture. The optical navigation input device includes a light source, an illumination aperture structure, and an image sensor. The light source directs a light beam toward a substantially specular illumination surface. Scattered light reflects off of a surface reflection feature along a scattered light path which is offset from a specular reflection path. The illumination aperture structure at least partially defines an illumination aperture interposed between the light source and the illumination surface. The illumination aperture produces a diffraction pattern that includes a diffraction discontinuity which is substantially free from diffracted light within a sector area outside of the light beam. The image sensor is disposed within the scattered light path at a location corresponding to the diffraction discontinuity. The image sensor receives the scattered light from the surface reflection feature and generates a navigation image of the surface reflection feature.
1. An optical navigation input device comprising:
a light source to direct a light beam toward a substantially specular illumination surface to illuminate a primary illumination spot at the illumination surface, wherein the light beam reflects off of the illumination surface along a specular reflection path, and scattered light reflects off of a surface reflection feature along a scattered light path which is offset from the specular reflection path;
an illumination aperture structure to at least partially define an illumination aperture interposed between the light source and the illumination surface, the illumination aperture to produce a diffraction pattern relative to the light beam, wherein the diffraction pattern comprises a diffraction discontinuity which is substantially free from diffracted light within a sector area outside of the light beam; and
an image sensor disposed within the scattered light path at a location corresponding to the diffraction discontinuity, wherein the image sensor is configured to receive the scattered light from the surface reflection feature and to generate a navigation image of the surface reflection feature.
2. The optical navigation input device of claim 1 , further comprising an imaging aperture structure to define an imaging aperture disposed within the scattered light path, wherein the imaging aperture is configured to pass at least a portion of the scattered light to the image sensor.
3. The optical navigation input device of claim 2 , further comprising an imaging lens structure disposed within the scattered light path and interposed between the imaging aperture and the image sensor, wherein the imaging lens structure comprises at least one optical element to direct the scattered light to the image sensor.
4. The optical navigation input device of claim 1 , further comprising a collimating lens structure interposed between the light source and the illumination aperture, wherein the collimating lens structure comprises at least one optical element to direct the light beam through the illumination aperture to the illumination surface.
5. The optical navigation input device of claim 1 , wherein the illumination aperture structure defines the illumination aperture with at least two sides which meet at a non-zero angle to form a corner in the illumination aperture.
6. The optical navigation input device of claim 5 , wherein the illumination aperture is aligned relative to the light beam to clip at least two sides of the light beam using the at least two sides of the illumination aperture structure.
7. The optical navigation input device of claim 5 , wherein the illumination aperture structure defines the illumination aperture as a quadrilateral which is larger in area than a cross-section of the light beam, and wherein the illumination aperture is offset relative to the light beam to clip at least two sides of the light beam using corresponding sides of the illumination aperture structure.
8. The optical navigation input device of claim 1 , wherein the light source comprises a laser light source.
9. The optical navigation input device of claim 1 , wherein the scattered light path is offset from the specular reflection path of the light beam by less than about 15 degrees.
10. The optical navigation input device of claim 1 , wherein the scattered light path is offset from the specular reflection path of the light beam by about 5 to 10 degrees.
11. An optical navigation input device comprising:
a light source to direct a light beam toward a substantially specular illumination surface, wherein the light beam reflects off of the illumination surface along a specular reflection path, and scattered light reflects off of a surface reflection feature along a scattered light path which is offset from the specular reflection path;
an imaging aperture structure to define an imaging aperture disposed within the scattered light path, wherein the imaging aperture is configured to receive the scattered light from the surface reflection feature and to direct at least a portion of the scattered light to an image sensor; and
an illumination aperture structure to at least partially define an illumination aperture interposed between the light source and the illumination surface, wherein the illumination aperture structure is offset relative to the light beam to clip the light beam and produce a diffraction pattern which is substantially directed away from the imaging aperture.
12. The optical navigation input device of claim 11 , wherein the image sensor is disposed within the scattered light path to receive the scattered light through the imaging aperture and to generate a navigation image of the surface reflection feature.
13. The optical navigation input device of claim 12 , wherein the illumination aperture structure defines the illumination aperture comprising a corner where two sides meet at a non-zero angle, wherein the corner of the illumination aperture is configured to produce a diffraction discontinuity within the diffraction pattern, wherein the diffraction discontinuity is substantially free from diffracted light.
14. The optical navigation input device of claim 12 , further comprising an imaging lens structure disposed within the scattered light path and interposed between the imaging aperture and the image sensor, wherein the imaging lens structure comprises at least one optical element to direct the scattered light to the image sensor.
15. The optical navigation input device of claim 14 , further comprising a collimating lens structure interposed between the light source and the illumination aperture, wherein the collimating lens structure comprises at least one optical element to direct the light beam through the illumination aperture to the illumination surface.
16. The optical navigation input device of claim 15 , wherein the illumination aperture structure defines the illumination aperture as a polygon shape with at least two sides which meet at a non-zero angle, wherein the two sides are aligned to clip the light beam and produce the diffraction pattern, wherein the diffraction pattern comprises a diffraction discontinuity which is substantially free from diffracted light within a sector area outside of the light beam.
17. The optical navigation input device of claim 11 , wherein the light source comprises a vertical cavity surface emitting laser (VCSEL).
18. A method for operating an optical navigation input device, the method comprising:
emitting a light beam through an asymmetrical clipping aperture at least partially defined by an illumination aperture structure to illuminate an illumination surface, the illumination aperture structure to clip the light beam and produce a diffraction pattern, wherein the diffraction pattern comprises a diffraction discontinuity which is substantially free from diffracted light within a sector area outside of the light beam;
passing scattered light through an imaging aperture defined by an imaging aperture structure, wherein the imaging aperture structure defines the imaging aperture at a location corresponding to the diffraction discontinuity substantially outside of a specular reflection path; and
generating a navigation image based on the scattered light.
19. The method of claim 18 , further comprising clipping two sides of the light beam based on an offset location of the illumination aperture structure relative to the light beam.
20. The method of claim 18 , further comprising blocking peripheral portions of the light beam while maintaining a uniformity of a central portion of the light beam.