Photoelectric sensor with droplet resistant face

• US 5,200,607 A
• Filed: 02/27/1992
• Issued: 04/06/1993
• Est. Priority Date: 02/27/1992
• Status: Expired due to Term

• Current Assignee: Pepperl + Fuchs GmbH
• Original Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Inventors: Klima, Catherine I.
• Primary Examiner(s): Nelms, David C.
• Assistant Examiner(s): Lee, John R.
• Application Number:
  US07/842,691
• Time in Patent Office: 404 Days
• Field of Search: 250/239, 250/216, 250/573, 250/577, 359/507
• US Class Current: 250/216
• CPC Class Codes: G01J 1/02 Details
• CPC Class Codes: G01J 1/0271 Housings; Attachments or accessories for photometers
• CPC Class Codes: G01J 2001/028 against liquid
• CPC Class Codes: G01N 21/15 Preventing contamination of the components of the optical system or obstruction of the light path
• CPC Class Codes: H01L 31/0203 Containers; Encapsulations , e.g. encapsulation of photodiodesfor photovoltaic devices H01L31/048; for organic photosensitive devices H10K30/80
• CPC Class Codes: H01L 31/02325 the optical elements not being integrated nor being directly associated with the device

Abstract

A photodetector is provided with a housing that has a discontinuity formed in an outer surface of its light transmissive portion. The discontinuity serves to inhibit liquid droplets from adhering to the outer surface of the endface in the region where the discontinuity is located. Alternative embodiments of the present invention include discontinuities formed in the outer surfaces of housing windows which have flat inner surfaces or inner surfaces which are shaped to formed lenses. By preventing liquid droplets from adhering to the outer surface of the window, the present invention prevents the reflective liquid surfaces of droplets from creating false signals for the photodetector by reflecting light back from the light source toward a light sensitive component.

Claims

1. A sensor, comprising:

a housing;

a light transmissive portion of said housing, said light transmissive portion having a first segment and a second segment, said light transmissive portion having an inner surface and a generally flat outer surface;

a discontinuity formed in said outer surface of said light transmissive portion, said discontinuity being disposed between said first and second segments;

a light source disposed within said housing and associated with said first segment to permit light from said light source to pass through said first segment in a direction from inside of said housing to outside of said housing;

a light sensitive component disposed within said housing and associated with said second segment to permit light to pass through said second segment in a direction from outside of said housing to said light sensitive component; and

means for preventing light from passing directly from said light source to said light sensitive component without passing through said light transmissive portion.

2. The sensor of claim 1, wherein:

said first segment is shaped to form a first lens.

3. The sensor of claim 2, wherein:

said second segment is shaped to form a second lens.

4. The sensor of claim 3, wherein:

said light transmissive portion is an integral portion of said housing.

5. The sensor of claim 4, wherein:

said housing is generally cylindrical.

6. The sensor of claim 5, wherein:

said light source is a light emitting diode.

7. The sensor of claim 6, wherein:

said light source is an infrared light emitting diode.

8. The sensor of claim 6, wherein:

said light source is a visible light emitting diode.

9. The sensor of claim 6, wherein:

said discontinuity is a groove formed in said outer surface.

10. The sensor of claim 6, wherein:

said discontinuity extends from one edge of said outer surface to a diametrically opposite edge of said outer surface.

11. A sensor, comprising:

a housing;

a light transmissive portion of said housing, said light transmissive portion having a first segment and a second segment, said light transmissive portion having an inner surface and an outer surface; and

a discontinuity formed in said outer surface of said light transmissive portion, said discontinuity being disposed between said first and second segments;

a light source disposed within said housing and associated with said first segment to permit light from said light source to pass out of said housing through said first segment; and

a light sensitive component disposed within said housing and associated with said second segment to permit light to pass into said housing through said second segment.

12. The sensor of claim 11, further comprising:

means for preventing light from passing directly from said light source to said light sensitive component without passing through said light transmissive portion.

13. The sensor of claim 11, wherein:

said first segment is shaped to form a first lens.

14. The sensor of claim 11, wherein:

said second segment is shaped to form a second lens.

15. The sensor of claim 11, wherein:

said light transmissive portion is an integral portion of said housing.

16. The sensor of claim 11, wherein:

said light source is a light emitting diode.

17. The sensor of claim 11, wherein:

said light source is an infrared light emitting diode.

18. The sensor of claim 11, wherein:

said light source is a visible light emitting diode.

19. The sensor of claim 11, wherein:

said discontinuity is a groove formed in said outer surface.

20. The sensor of claim 11, wherein:

said discontinuity extends from one edge of said outer surface to a diametrically opposite edge of said outer surface.

21. The sensor of claim 11, wherein:

said housing is cylindrical.

22. A photoelectric sensor, comprising:

a housing;

an window of said housing, said window having a first portion and a second portion, said window having an inner surface and an outer surface;

a light source disposed within said housing, said first portion being associated with said light source to permit light from said light source to pass through said first portion in a direction from inside of said housing to outside of said housing;

a light sensitive component disposed within said housing, said second portion being associated with said light sensitive component to permit light to pass through said second portion in a direction from outside of said housing to inside of said housing;

means for preventing light from passing directly from said light source to said light sensitive component within said housing; and

a discontinuity formed in said outer surface of said window, said discontinuity being disposed between said first and second portions.

23. The sensor of claim 22, wherein:

said first and second portions are each shaped to form a lens on said inner surface.

24. The sensor of claim 22, wherein:

said discontinuity extends across the entire diametric length of said outer surface.

25. The sensor of claim 22, wherein:

said light source is a light emitting diode.

26. The sensor of claim 25, wherein:

said light emitting diode in an infrared light emitting diode.

27. The sensor of claim 25, wherein:

said light emitting diode is a visible light emitting diode.

28. The sensor of claim 22, wherein:

said first and second portions are each generally semicircular and disposed in a side by side relationship.