Optical positioning device having shaped illumination

• US 7,285,766 B2
• Filed: 05/16/2005
• Issued: 10/23/2007
• Est. Priority Date: 05/21/2004
• Status: Active Grant

• Current Assignee: Monterey Research, LLC (Vector Capital Corporation)
• Original Assignee: Silicon Light Machines Corporation (SCREEN Holdings Co., Ltd.)
• Inventors: LeHoty, David A., Carlisle, Clinton B., Trisnadi, Jahja I., Roxlo, Charles B.
• Primary Examiner(s): Epps, Georgia
• Assistant Examiner(s): Ko, Tony
• Application Number:
  US11/129,967
• Publication Number:
  US 20050258347A1
• Time in Patent Office: 890 Days
• Field of Search: 250/221, 250/208.1, 250/226, 345157-169, 356/498
• US Class Current: 250/221
• 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: H01L 27/1446 in a repetitive configuration
• CPC Class Codes: H01L 31/02024 Position sensitive and lateral effect photodetectors; Quadrant photodiodes

Abstract

One embodiment relates to an optical displacement sensor for sensing relative movement between a data input device and a surface by determining displacement of optical features in a succession of frames. The sensor includes an illuminator and a detector. The illuminator has a light source and illumination optics to illuminate a portion of the surface with a planar phase-front. The detector has a plurality of photosensitive elements and imaging optics. The illuminator and the detector are configured such that the illuminated portion of the surface is less than fifty percent larger than a field of view of the photosensitive elements of the detector. Other embodiments are also described.

Claims

1. An optical displacement sensor for sensing relative movement between a data input device and a surface by determining displacement of optical features in a succession of frames, the sensor comprising:

an illuminator having a light source configured to originate an illumination beam and illumination optics configured to transform the illumination beam to a non-circular shape and further configured to illuminate a non-circular portion of the surface by the non-circular-shaped illumination beam, wherein the non-circular-shaped illumination beam has a substantially planar phase-front; and

a detector having a plurality of photosensitive elements in a non-circular arrangement and imaging optics configured to receive non-circular-shaped illumination reflected from the surface and to image the reflected non-circular-shaped illumination onto the non-circular arrangement of photosensitive elements,

wherein the plurality of photosensitive elements includes a first plurality of photosensitive elements arranged in substantially straight line along a first axis, and a second plurality of photosensitive elements arranged in substantially straight line along a second axis, and wherein the second axis is non-parallel to the first axis.

2. The optical displacement sensor according to claim 1, wherein the illumination optics comprise diffractive and refractive optics to minimize light falling outside of the field of view of the detector.

3. The optical displacement sensor according to claim 1, wherein the second axis is at an angle to the first axis of about 90 degrees.

4. The optical displacement sensor according to claim 1, wherein the first and second plurality of photosensitive elements are arranged along the first axis and the second axis to form an ‘

L’

, ‘

T’

, ‘

+’

, ‘

X’

, or‘

V’

shaped non-circular arrangement, and wherein the reflected non-circular-shaped illumination is of a substantially similar shape as said non-circular arrangement of photosensitive elements.

5. The optical displacement sensor according to claim 4, wherein the illuminator is further configured such that the illuminated portion of the surface defines a corresponding ‘

L’

, ‘

T’

, ‘

+’

, ‘

X’

, or ‘

V’

shape on the surface.

6. The optical displacement sensor according to claim 1, wherein the illuminator is further configured such that the illuminated non-circular portion of the surface corresponds in shape and area to the field of view of the non-symmetric arrangement of photosensitive elements of the detector.

7. The optical displacement sensor according to claim 1, wherein the illuminator is further configured such that the illuminated portion of the surface is sufficiently larger than field of view of the detector to provide a predetermined margin for errors in operation and fabrication of optical displacement sensor components, and wherein the illuminated non-circular portion of the surface is less than fifty percent more than the field of view of the non-circular arrangement of photosensitive elements of the detector.

8. The optical displacement sensor according to claim 1, wherein the photosensitive elements comprise photodiodes, and the light source comprises a laser.

9. The optical displacement sensor according to claim 1, wherein the optical displacement sensor is a speckle-based displacement sensor adapted to identify a location on the surface based on a complex interference pattern created by light reflected from the surface, and wherein the laser comprises a Vertical Cavity Surface Emitting Laser (VCSEL).

10. The optical displacement sensor according to claim 1, wherein the illuminator and the detector are configured such that substantially all of the illuminated non-circular portion of the surface falls within the field of view of the non-circular arrangement of photosensitive elements.

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 frames, the method comprising:

generating illumination from a light source;

mapping the illumination by illumination optics onto a non-circular portion of the surface such that the illumination beam has a substantially planar phase-front;

reflecting non-circular-shaped illumination from the illuminated non-circular portion of the surface; and

mapping the reflected non-circular-shaped illumination by imaging optics onto a corresponding non-circular arrangement of photosensitive elements in the detector,

wherein the illuminated non-circular portion of the surface is less than fifty percent larger than a field of view of the non-circular arrangement of photosensitive elements,

wherein a first plurality of the photosensitive elements are arranged in a substantially straight line along a first axis, and a second plurality of the photosensitive elements are arranged in a substantially straight line along a second axis, and wherein the second axis is non-parallel to the first axis.

12. The method according to claim 11, wherein mapping the illumination by the illumination optics comprises refracting and diffracting the illumination such that the illuminated non-circular portion of the surface corresponds in shape to the field of view of the non-circular arrangement of photosensitive elements in the detector.

13. The method according to claim 11, wherein the photosensitive elements are arranged non-circularly so as to form a shape from a group of shapes consisting of ‘

L’

, ‘

T’

, ‘

+’

, ‘

X’

, and ‘

V’

shapes, and wherein the illuminated non-symmetric portion of the surface forms a corresponding shape.

14. The method according to claim 11 wherein mapping the illumination comprises illuminating the non-circular portion of the surface to define an ‘

L’

, ‘

T’

, ‘

+’

, ‘

X’

, or ‘

V’

shape on the surface, the illuminated non-circular portion overlapping and corresponding in shape to the field of view of the non-circular arrangement of photosensitive elements of the detector.