PHOTOSENSOR ARRAY FOR OPTICAL ENCODER

• US 20080156973A1
• Filed: 12/29/2006
• Published: 07/03/2008
• Est. Priority Date: 12/29/2006
• Status: Abandoned Application

• Current Assignee: Avago Technologies ECBU IP Singapore Pte Limited (Broadcom, Inc.)
• Original Assignee: Avago Technologies ECBU IP Singapore Pte Limited (Broadcom, Inc.)
• Inventors: Wong, Weng Fei, Lum, Chee Foo, Foo, Siang Leong
• Application Number:
  US11/618,691
• Publication Number:
  US 20080156973A1
• Time in Patent Office: Days
• US Class Current: 250/231.16
• CPC Class Codes: G01D 5/36 Forming the light into pulses

Abstract

An optical encoder. A reflective optical encoder includes a reflective coding element, a plurality of emitters, and a detector. The reflective coding element includes a track of alternating reflective and non-reflective sections. Each of the plurality of emitters is configured to generate corresponding light signals incident on the track of the coding element. The detector is configured to detect the corresponding light signals reflected off of the reflective sections of the track. In one embodiment, the detector includes a plurality of photosensors positioned in separate photosensor groupings, and each photosensor grouping corresponds to one of the plurality of emitters. Embodiments of the optical encoder are suitable for small form factor encoders and improve the ease encoder assembly.

Claims

1. A reflective optical encoder comprising:

a reflective coding element comprising a track of alternating reflective and non-reflective sections;

a plurality of emitters configured to generate corresponding light signals incident on the track of the coding element; and

a detector configured to detect the corresponding light signals reflected off of the reflective sections of the track, wherein the detector comprises a plurality of photosensors positioned in separate photosensor groupings, each photosensor grouping corresponding to one of the plurality of emitters.

2. The reflective optical encoder of claim 1 wherein the plurality of photosensors are positioned near edges of the detector.

3. The reflective optical encoder of claim 1 further comprising an encapsulant to encapsulate the plurality of emitters and the plurality of photosensors.

4. The reflective optical encoder of claim 3 wherein the encapsulant forms a plurality of lenses, each lens aligned with one of the photosensor groupings and a corresponding emitter.

5. The reflective optical encoder of claim 4 wherein each lens is configured to direct the light signal from the corresponding emitter to the track, and to direct the reflected light signal from the track to the corresponding photosensor grouping.

6. The reflective optical encoder of claim 1 wherein the coding element comprises a code wheel.

7. The reflective optical encoder of claim 1 wherein the coding element comprises a code strip.

8. The reflective optical encoder of claim 1 wherein at least one of the separate photosensor groupings comprises a single photosensor.

9. The reflective optical encoder of claim 8 wherein the single photosensor comprises a monitor photosensor.

10. The reflective optical encoder of claim 1 wherein at least one of the separate photosensor groupings comprises more than one photosensor.

11. An optical encoder comprising:

means for generating multiple light signals incident on a track of a coding element, wherein the track comprises coding sections; and

means for detecting motion of the coding element; and

means for reducing cross-talk of the multiple light signals.

12. The optical encoder of claim 11 further comprising means for encapsulating the optical encoder.

13. The optical encoder of claim 11 further comprising means for directing the light signals to the track, and for directing reflected light signals to the detecting means.

14. The optical encoder of claim 11 wherein the coding element comprises a reflective coding element.

15. The optical encoder of claim 11 wherein the coding element comprises an imaging coding element.

16. A detector within an optical encoder, the detector comprising:

a first photosensor grouping positioned near a first edge of the detector, wherein the first photosensor grouping comprises at least one photosensor; and

a second photosensor grouping positioned at an opposite edge of the detector, wherein the second photosensor grouping comprises at least one photo sensor.

17. The detector of claim 16 wherein the first and second photosensor groupings are positioned to align with first and second emitters.

18. The detector of claim 17 wherein the first and second photosensor groupings are positioned to align with first and second optical lenses.

19. The detector of claim 16 wherein the first and second photosensor groupings comprise different numbers of photosensors.

20. The detector of claim 16 wherein the coding element comprises a code wheel, wherein the first photosensor grouping is positioned along a first radial line of the code wheel at a first non-zero angle with respect to the first edge of the detector, and the second photosensor grouping is positioned along a second radial line of the code wheel at a second non-zero angle with respect to the opposite edge of the detector.