Optical encoder module

• US 7,279,674 B2
• Filed: 08/15/2001
• Issued: 10/09/2007
• Est. Priority Date: 08/17/2000
• Status: Expired due to Fees

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Avago Technologies ECBU IP Singapore Pte Limited (Broadcom, Inc.)
• Inventors: Ng, Kee-Yean, Chin, Yee-Loong, Chong, Chee-Keong, Lee, Chin-Yun, Fo, Kok-Hing
• Primary Examiner(s): Luu; Thanh X.
• Assistant Examiner(s): YAM, STEPHEN K
• Application Number:
  US10/344,836
• Publication Number:
  US 20050068773A1
• Time in Patent Office: 2,246 Days
• Field of Search: 250/231.13, 250/239, 250/231.14, 250/231.17, 250/231.18, 257/81, 257/100, 257/433
• US Class Current: 250/231.13
• CPC Class Codes: G01D 5/34715 Scale reading or illumination devices

Abstract

An optical encoder module is employed to detect light modulated by a moveable member (e.g., code wheel). The optical encoder includes an emitter having a light-emitting element, and a transparent medium encapsulating the light-emitting element. The transparent medium has a convex aspherical external surface shaped so as to focus light received from the light-emitting element into a substantially collimated beam of light using a single refractive interface for illuminating the movable member. The optical encode module also includes a detector facing the emitter for detecting modulated light of the collimated beam transmitted through the movable member.

Claims

1. A compact optical encoder module, comprising a housing having upper and lower recesses, a light emitting element located in the lower recess, a first transparent material encapsulating the light emitting element and forming a single optical interface convex aspherical lens thereover, a light detector located in the upper recess and positionally aligned with the lens, a second transparent material encapsulating the light detector, and a moveable member disposed in a gap between the light emitting element and the light detector and configured to modulate a light beam passing therebetween, the light emitting element, the lens and the first transparent material being configured to focus light emitted by the light emitting element into a substantially collimated light beam directed towards the light detector.

2. The compact optical encoder module according to claim 1, wherein the convex aspherical lens is radially symmetric about an optical axis.

3. The compact optical encoder module according to claim 1, wherein the light-emitting element is positioned substantially along the optical axis of the convex aspherical lens.

4. The compact optical encoder module according to claim 1, wherein the transparent encapsulating material is an epoxy compound.

5. The act optical encoder module according to claim 1, wherein the convex aspherical lens is produced by molding the transparent encapsulating material.

6. The compact optical encoder module according to claim 1, wherein the light-emitting element is a light emitting diode.

7. The compact optical encoder module according to claim 1, wherein the light emitting element is electrically coupled to a lead-frame, the lead-frame being at least partially encapsulated by the first transparent material.

8. The compact optical encoder module according to claim 1, wherein the movable member is a code wheel.

9. The compact optical encoder module according to claim 1, further comprising a locking projection configured to lock the light-emitting element and the detector into a locking position with respect to one another.