Reflective encoder with three-dimensional code carrier

• US 7,358,481 B2
• Filed: 03/06/2006
• Issued: 04/15/2008
• Est. Priority Date: 03/06/2006
• Status: Expired due to Fees

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Avago General IP Pte Limited
• Inventors: Tan, Hock Aun, Lum, Chee Foo, Yeoh, Theng Hooi
• Primary Examiner(s): Le; Que Tan
• Assistant Examiner(s): BUI PHO, PASCAL M
• Application Number:
  US11/369,287
• Publication Number:
  US 20070215799A1
• Time in Patent Office: 771 Days
• Field of Search: 25023113-23118, 250/237.G, 341/11, 341/13, 356614-622, 345/165
• US Class Current: 250/231.13
• CPC Class Codes: G01D 5/285 using a movable mirror
• CPC Class Codes: G01D 5/34707 Scales; Discs, e.g. fixation, fabrication, compensation

Abstract

An encoder having a code pattern on a carrier and an emitter detector module is disclosed. The code pattern includes alternating reflective and opaque regions on a carrier that includes a planar surface. The emitter-detector module includes a light source that generates light and directs a portion of the generated light at the first side of the carrier and a first detector that detects light reflected from one of the reflective regions. The reflective regions include a three-dimensional element for directing light from the light source onto the first detector. The element has a surface that is inclined at an oblique angle with respect to the planar surface. The code pattern moves with respect to the emitter-detector module. The three-dimensional element can include a reflective imaging element that images the light source onto a surface of the first detector.

Claims

1. An encoder comprising:

a code pattern comprising multiple first regions and multiple second regions on a carrier comprising a planar surface, said first regions being reflective regions, said first and second regions being relatively positioned in an alternating pattern; and

an emitter-detector module comprising a light source that generates light and directs a portion of said generated light at a first side of said carrier and a first detector that detects said light reflected from one of said first regions,

wherein each of said first regions comprises a three-dimensional element for directing said light from said light source onto said first detector, said element having a surface that is inclined at an oblique angle with respect to said planar surface and wherein said code pattern moves with respect to said emitter-detector module,

wherein said second regions are configured such that said light from said light source incident on said second regions is not directed to said first detector, and

wherein said emitter-detector module comprises a second detector that is displaced from said first detector and wherein each of said second regions comprises a second three-dimensional element, which is distinct and separate from said first three-dimensional element, that reflects said light from said light source into said second detector such that said light from said light source incident on said first three-dimensional element of said first regions is exclusively directed to said first detector and said light from said lights source incident on said second three-dimensional element of said second regions is exclusively directed to said second detector.

2. The encoder of claim 1 wherein said three-dimensional element comprises a reflective imaging element that images said light source onto a surface of said first detector.

3. The encoder of claim 2 wherein said reflective imaging element comprises a parabolic reflector.

4. The encoder of claim 1 wherein said second regions comprise a planar surface that absorbs light.

5. The encoder of claim 1 wherein said second regions comprise a transparent surface that transmits light that passes through said carrier.