Infrared Attenuating or Blocking Layer in Optical Proximity Sensor

• US 20110204233A1
• Filed: 04/30/2011
• Published: 08/25/2011
• Est. Priority Date: 06/30/2009
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Avago Technologies ECBU IP Singapore Pte Limited (Broadcom, Inc.)
• Inventors: Saravanan, Rani, Tan, Wee Sin, Costello, James
• Granted Patent: US 8,957,380 B2
• Time in Patent Office: Days
• US Class Current: 250/338.4
• CPC Class Codes: G01S 17/04 Systems determining the presence of a target
• CPC Class Codes: G01S 7/4813 Housing arrangements
• CPC Class Codes: H03K 17/941 using an optical detector H03K17/968 takes precedence
• CPC Class Codes: H03K 2017/9455 constructional details
• CPC Class Codes: H03K 2217/94108 making use of reflection
• CPC Class Codes: Y10T 29/49826 Assembling or joining

Abstract

An optical proximity sensor is provided that comprises an infrared light emitter an infrared light detector, a first molded optically transmissive infrared light pass component disposed over and covering the light emitter and a second molded optically transmissive infrared light pass component disposed over and covering the light detector. Located in-between the light emitter and the first molded optically transmissive infrared light pass component, and the light detector and the second molded optically transmissive infrared light pass component is a gap. Layers of infrared opaque, attenuating or blocking material are disposed on at least some of the external surfaces forming the gap to substantially attenuate or block the transmission of undesired direct, scattered or reflected light between the light emitter and the light detector, and thereby minimize optical crosstalk and interference between the light emitter and the light detector.

Claims

1. An optical proximity sensor, comprising:

an infrared light emitter operably connected to and driven by a light emitter driving circuit;

a light detector operably connected to and driven by a detector sensing circuit;

a first component disposed over and covering at least portions of the light emitter and comprising first external surfaces thereof, and

a second component disposed over and covering at least portions of the light detector and comprising second external surfaces thereof, the first and second components being separated at least partially by a gap disposed therebetween;

wherein the sensor is configured such that at least a first portion of light emitted by the light detector passes through a portion of the first component, at least a second portion of the first portion of light reflected from an object of interest in proximity to the sensor passes through a portion of the second component for detection by the light detector, a layer of infrared attenuating or blocking material is disposed over at least portions of the first and second external surfaces located adjacent to the gap, and the infrared attenuating or blocking material is configured to attenuate or block substantially the transmission of undesired direct, scattered or reflected infrared light between the light emitter and the light detector and thereby minimize optical crosstalk and interference between the light emitter and the light detector.

2. The optical proximity sensor of claim 1, wherein the layer of infrared light attenuating material is one of a paint, an ink and a dye.

3. The optical proximity sensor of claim 1, wherein the infrared light attenuating material comprises an infrared cut or blocking additive.

4. The optical proximity sensor of claim 1, wherein the infrared light attenuating material is disposed substantially over at least most of the first and second external surfaces.

5. The optical proximity sensor of claim 1, wherein the layer of infrared light attenuating material has a thickness ranging between about 2 microns and about 100 microns.

6. The optical proximity sensor of claim 1, wherein the layer of infrared light attenuating material has a thickness ranging between about 10 microns and about 40 microns.

7. The optical proximity sensor of claim 1, wherein the layer of infrared light attenuating material is applied to the at least portions of the first and second external surfaces by one of spraying, dipping, brushing, rolling, electrodepositing, and sputtering the infrared light attenuating material thereon.

8. The optical proximity sensor of claim 1, wherein at least one of the first and second components is a molded or casted infrared light pass material.

9. The optical proximity sensor of claim 8, wherein the molded or casted infrared light pass material comprises an optically transmissive epoxy, polymer or plastic.

10. The optical proximity sensor of claim 1, further comprising a substrate upon which the light emitter and the light detector are operably mounted.

12. The optical proximity sensor of claim 10, wherein the substrate is a printed circuit board (“

PCB”

).

13. The optical proximity sensor of claim 1, wherein at least one of the light emitter and light detector is a semiconductor die.

14. The optical proximity sensor of claim 1, further comprising at least one integrated circuit operably connected to the light emitter and the light detector, the integrated circuit being configured to control the operation of the light detector and the light detector and to process output signals provided by the light detector.

15. The optical proximity sensor of claim 14, wherein the at least one integrated circuit further comprises a proximity sensor application specific integrated circuit (ASIC) and a master control unit (MCU).

16. The optical proximity sensor of claim 1, wherein the optical proximity sensor is incorporated into a portable electronic device.

17. The optical proximity sensor of claim 16, wherein the portable electronic device is a mobile telephone, a personal data assistant (PDA), a laptop computer, a notebook computer, or a computer.

18. The optical proximity sensor of claim 1, wherein the light emitter is an LED.

19. The optical proximity sensor of claim 1, wherein the light detector is a positive-intrinsic-negative (“

PIN”

) diode.

20. The optical proximity sensor of claim 1, wherein a molded optically transmissive lens is formed over the light emitter or the light detector.

21. A method of making an optical proximity sensor, comprising:

mounting an infrared light emitter on a substrate;

mounting an infrared light detector on the substrate, the infrared light detector being spaced apart from the infrared light emitter on the substrate;

forming or placing a first infrared light pass component over at least portions of the light emitter, the first infrared light pass component comprising first external surfaces;

forming or placing a second infrared light pass component over at least portions of the light detector such that at least portions of the first and second components are separated by a gap, the second infrared light pass component comprising second external surfaces, and

forming or placing a layer of infrared light attenuating or blocking material over at least portions of the first and second external surfaces located adjacent to the gap, the infrared light attenuating material being configured to attenuate or block substantially the transmission of undesired direct, scattered or reflected infrared light between the light emitter and the light detector and thereby minimize optical crosstalk and interference between the light emitter and the light detector.

22. The method of claim 21, wherein the layer of infrared light attenuating material is one of a paint, an ink and a dye.

23. The method of claim 21, further comprising adding an infrared cut or blocking additive to the infrared light attenuating material.

24. The method of claim 21, further comprising forming or placing the infrared light attenuating material over substantially most of the first and second external surfaces.

25. The method of claim 21, wherein the layer of infrared light attenuating material has a thickness ranging between about 2 microns and about 100 microns.

26. The method of claim 21, wherein the layer of infrared light attenuating material has a thickness ranging between about 10 microns and about 40 microns.

27. The method of claim 21, wherein the layer of infrared light attenuating material is formed or placed over the at least portions of the first and second external surfaces by one of spraying, dipping, brushing, rolling, electrodepositing, and sputtering the infrared light attenuating material thereon.

28. The method of claim 21, wherein the first and second infrared light pass components are molded, transfer-molded, casted, or sheet-casted.

29. The method of claim 21, wherein optically transmissive lenses are formed over the light emitter and the light detector when the first or second infrared light pass component is molded or casted.