Optical transducer for continuously determining liquid level

• US 7,161,165 B2
• Filed: 07/07/2004
• Issued: 01/09/2007
• Est. Priority Date: 07/07/2004
• Status: Expired due to Fees

• Current Assignee: Opti Sensor Systems, LLC
• Original Assignee: Opti Sensor Systems, LLC
• Inventors: Wirthlin, Alvin R.
• Primary Examiner(s): Luu; Thanh X.
• Assistant Examiner(s): YAM, STEPHEN K
• Application Number:
  US10/886,174
• Publication Number:
  US 20060006353A1
• Time in Patent Office: 916 Days
• Field of Search: 250573-577, 250/227.24, 250/227.25, 385/12, 732/90.R, 732/93
• US Class Current: 250/577
• CPC Class Codes: G01F 23/292 Light , e.g. infrared or ultraviolet
• CPC Class Codes: G01F 23/2922 with light-conducting sensing elements, e.g. prisms

Abstract

An optical transducer for determining liquid level within a container includes a sensing probe having a first elongate measurement face and a second elongate measurement face that converges toward the first measurement face. A light source is positioned for directing radiant energy into the sensing probe and a photosensor is positioned for detecting an amount of radiant energy exiting the sensing probe. With this arrangement, a change in the amount of radiant energy as detected by the photosensor is indicative of a change in liquid level within the container.

Claims

1. An optical transducer for determining liquid level within a container, the optical transducer comprising:

a first sensing probe having a first elongate measurement face and a second elongate measurement face that converges toward the first elongate measurement face, at least a portion of the first and second elongate measurement faces being oriented at an angle less than 90 degrees;

a first light source positioned for directing radiant energy into the sensing probe;

a first photosensor positioned for detecting an amount of radiant energy exiting the sensing probe;

wherein a change in the amount of radiant energy as detected by the photosensor is indicative of a change in liquid level within the container;

a liquid level switch for sensing a predetermined liquid level within the container, the liquid level switch comprising;

a second sensing probe having an elongate core with a measurement tip; and

a second photosensor positioned for detecting an amount of radiant energy exiting the second sensing probe;

wherein a change in the amount of radiant energy as detected by the second photosensor is indicative of the predetermined liquid level.

2. An optical transducer according to claim 1, wherein the sensing probe further comprises a third elongate measurement face that converges toward the second elongate measurement face.

3. An optical transducer according to claim 2, wherein the third elongate measurement face also converges toward the first elongate measurement face, at least a portion of the second and third elongate measurement faces being oriented at an angle less than 90 degrees such that the sensing probe is triangular in cross section.

4. An optical transducer according to claim 3, and further comprising a film covering the measurement faces.

5. An optical transducer according to claim 4, wherein the first sensing probe comprises a first transparent material with a first refractive index and the film comprises a second material with a second refractive index lower than the first refractive index.

6. An optical transducer according to claim 5, wherein the first transparent material comprises acrylic and the second transparent material comprises a fluorinated polymer.

7. An optical transducer according to claim 1, wherein the second elongate measurement surface is curved such that the sensing probe is half-round in cross section.

8. An optical transducer according to claim 1, and further comprising a film covering the measurement faces.

9. An optical transducer according to claim 8, wherein the first sensing probe comprises a first transparent material with a first refractive index and the film comprises a second material with a second refractive index lower than the first refractive index.

10. An optical transducer according to claim 9, wherein the first transparent material comprises acrylic and the second transparent material comprises a fluorinated polymer.

11. An optical transducer according to claim 1, wherein the light source and photosensor are positioned at a first end of the first sensing probe and further comprising a reflective element positioned at a second opposite end of the first sensing probe to redirect radiant energy from the light source toward the first end.

12. An optical transducer according to claim 1, wherein the liquid level switch further comprises

a second light source positioned for directing radiant energy into the second sensing probe toward the measurement tip.

13. An optical transducer according to claim 12, and further comprising a film covering the first and second sensing probes.

14. An optical transducer according to claim 13, wherein the first and second sensing probes comprise a first transparent material with a first refractive index and the film comprises a second material with a second refractive index lower than the first refractive index.

15. An optical transducer according to claim 14, wherein at least one of the first and second refractive indices is greater than a refractive index of the liquid being measured.

16. An optical transducer according to claim 1, wherein the first sensing probe comprises a first transparent material with a refractive index that is greater than a refractive index of the liquid being measured.

17. An optical transducer for determining liquid level within a container, the optical transducer comprising:

a first sensing probe having a first elongate measurement face and a second elongate measurement face that converges toward the first elongate measurement face, at least a portion of the first and second elongate measurement faces being oriented at an angle less than 90 degrees;

a first light source positioned for directing radiant energy into the sensing probe;

a first photosensor positioned for detecting an amount of radiant energy exiting the sensing probe;

wherein a change in the amount of radiant energy as detected by the photosensor is indicative of a change in liquid level within the container;

a liquid level switch for sensing a predetermined liquid level within the container; and

means for sensing a value of the liquid level switch and compensating liquid level measurement of the first sensing probe based on the value of the liquid level switch.