Compact and low profile optical navigation device
View Patent ↗An optical navigation device detects relative motion of non-optically flat surfaces, e.g. fingers by comparing the captured images of the surface texture, e.g. ridges on the finger. Within a housing, a light source and a sensor array are positioned proximately. The sensor array is mounted on a substrate. A lens array interposes the surface to be imaged and the sensor array such that a 1:1 image of the surface, e.g. finger surface of the user onto the 2D sensor array, is formed. The micro-lenses may be designed to match individual pixels on the sensor array, or each element of the lens array is used to cover a group of pixels on the sensor. The micro-lenses may be positioned such that the image is formed onto the sensor array or formed in a plane in space such that the image is defocused from the surface.
1. An apparatus comprising:
a housing;
an M×N array of elements for collecting electromagnetic waves from a surface, where M>1 and N≧1; and
a motion detection circuit, having a sensor array for receiving the electromagnetic waves, determining relative motion in the directions along the first and second axes;
wherein the M×N array is positioned to form an image of a plane in space that is different from the surface onto the sensor array.
2. An apparatus as defined in claim 1 wherein the electromagnetic waves are selected from a group that include visible light, infrared light, and microwaves.
3. An apparatus, as defined in claim 2 , furthering comprising a light source, positioned within the housing, operable to emit the electromagnetic wave towards the surface.
4. An apparatus, as defined in claim 3 , each element of the M×N array corresponds to at least a fraction a sensor in the sensor array.
5. An apparatus, as defined in claim 3 , each element of the M×N array corresponds to a single sensor in the sensor array.
6. An apparatus, as defined in claim 3 , each element of the M×N array corresponds to a group of sensors in the sensor array.
7. An apparatus, as defined in claim 3 , wherein the light source emits visible or infrared light.
8. An apparatus, as defined in claim 7 , wherein each element of the M×N array is a lens.
9. An apparatus, as defined in claim 8 , the lens is a refractive, diffractive or hybrid element.
10. An apparatus, as defined in claim 3 , wherein the light source is one of a coherent, quasi-coherent, and non-coherent light source.
11. An apparatus, as defined in claim 10 , wherein the light source is a coherent light source, the coherent light source selected from a group consisting of laser diodes and vertical cavity surface emitting lasers.
12. An apparatus, as defined in claim 3 , wherein the light source is a non-coherent or quasi-coherent light source, the light source selected from a group consisting of light emitting diodes (LED) and broadband light sources.
13. An apparatus, as defined in claim 3 , wherein the sensor array is one of a CCD and a CMOS imager.
14. An apparatus, as defined in claim 3 , the patterns being selected from a group including speckle, diffraction, and surface image.
15. A method comprising:
applying an electromagnetic source towards a surface;
forming a pattern corresponding to a reflection of the surface by applying a an M×N array of collection elements, where M>1 and N≧1;
detecting a series of patterns using a sensor array; and
analyzing the patterns to determine relative motion;
wherein the M×N array is an array of lenses positioned to form an image of a plane in space that is different from the surface onto the sensor array.
16. The method, as defined in claim 15 , wherein:
the electromagnetic source emits light in the optical wavelength range; and
wherein the pattern is selected from a group including speckle, diffraction, and surface images.
17. The method, as defined in claim 16 , wherein the light source is a coherent light source selected from a group consisting of laser diodes and vertical cavity surface emitting lasers.
18. The method, as defined in claim 16 , wherein the light source is one of a non-coherent and a quasi-coherent light source, the light source selected from a group consisting of light emitting diodes (LED) and broadband light source.
19. The method, as defined in claim 15 , wherein:
the sensor array is one of a CCD and a CMOS image array.
20. An apparatus comprising:
a housing;
a motion detection circuit, having a sensor array to receive electromagnetic waves, the motion detection circuit to determine a relative motion in a direction along at least one axes; and
an M×N array of elements interposed between the motion detection circuit and a light source, where M>1 and N≧1 the M×N array of elements to collect the electromagnetic waves from a surface, wherein each element of the M×N array corresponds to a group of sensors in the sensor array.
21. An apparatus, as defined in claim 20 , wherein the M×N array is positioned to form a pattern of the surface onto the sensor array.
22. An apparatus, as defined in claim 20 , wherein the M×N array of elements comprises an array of lenses, each lens having a reduced focal length, and the array of lenses having an f-number approximately equivalent to a single lens element.
23. An apparatus, as defined in claim 20 , wherein the M×N array of elements is integrated to the sensor array at a wafer level.