US4650992A
Expired / Lapsed
US
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Optical sensor constituting a light transmissive medium with luminescent particles
Assignee: Individual
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Filing: 1983-12-20
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Granted: 1987-03-17
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Expires: 2003-12-20
Abstract
Abstract An optical sensor is made of light transmissive material and has luminescent particles distributed throughout its volume. The luminescent particles are excited by a suitable type of energy, preferably light. As they return to their original state, they emit light uniformly in all directions. Depending upon the relationship of the index of refraction of the sensor body material to that of a test medium abutting a boundary surface of the sensor body, part of the luminescent light is reflected, the remainder passing into the test medium with a change in direction (refraction). When the test medium is optically less dense than the sensor medium luminescent light incident on the boundary surface at an angle exceeding the critical angle undergoes total reflection. For an elongated sensor body, this totally reflected part is transmitted to the end faces of the sensor, where its intensity constitutes a desired measure of a physical quantity. The sensor is effective for any physical characteristic which can change the index of refraction of the surrounding medium or that of the sensor itself. In addition, the quantity of totally reflected light can be varied also by changing the quantity of primary light applied to the sensor. Possible applications of a sensor of this type include measurements of liquid level in a container, the measurement of concentrations of a given component in a solution, temperature and pressure measurements of gases, monitoring of the boiling point of a liquid at very low temperatures, measurements of humidity, and a variety of position and length measurements. The sensor can also be used as a unit in a keyboard.
Inventors
- 👤 Wolfgang Ruhrmann
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 08:28
CPC Classifications
G; G01; G01J; G01J1/00; G01J1/58; G01D; G01D5/00; G01D5/26; G01F; G01F23/00; G01F23/22; G01F23/28; G01F23/284; G01F23/292; H; H03; H03K; H03K17/00; H03K17/94; H03K17/96; H03K17/9627; H03K17/9629; H03K17/9638; H03M; H03M11/00; H03M11/26
Claims Analysis
Total Claims: 37
Claim 1
Independent Claim
181 words
Apparatus for measuring the value of a predetermined characteristic, comprising in combination a source of primary energy, a test medium having a test index of refraction, a sensor element made of a refracting medium having a predetermined index of refraction essentially dissimilar from said test index of refraction, and including a multiplicity of particles distributed therethrough for radiating secondary energy in the form of light in response to excitation by said primary energy, said sensor element having a boundary surface at least in part transmissive to said secondary energy, and being coupled to said test medium, and an output location receiving a part of said secondary energy, said secondary energy varying as a function of the value of said predetermined chracteristic, secondary energy receiving means coupled to said sensor element at said output location, and an optical comparison medium optically coupled to said boundary surface of said sensor element, said comparison medium being optically less dense than said test medium, and less dense than said refracting medium, said output location being arranged at said boundary surface adjacent to said comparison medium.
Claim 2
Dependent Claim
181 words
Apparatus for measuring the value of a predetermined characteristic, comprising in combination a source of primary energy, a test medium having a test index of refraction, a sensor element made of a refracting medium having a predetermined index of refraction essentially dissimilar from said test index of refraction, and including a multiplicity of particles distributed therethrough for radiating secondary energy in the form of light in response to excitation by said primary energy, said sensor element having a boundary surface at least in part transmissive to said secondary energy, and being coupled to said test medium, and an output location receiving a part of said secondary energy, said secondary energy varying as a function of the value of said predetermined chracteristic, secondary energy receiving means coupled to said sensor element at said output location, and an optical comparison medium optically coupled to said boundary surface of said sensor element, said comparison medium being optically less dense than said test medium, and less dense than said refracting medium, said output location being arranged at said boundary surface adjacent to said comparison medium.
Claim 3
Dependent Claim
14 words
Apparatus as set forth in claim 1 wherein said primary energy is light energy.
Claim 4
Dependent Claim
15 words
Apparatus as set forth in claim 2, wherein said light source is a laser diode.
Claim 5
Dependent Claim
14 words
Apparatus as set forth in claim 2, wherein said light energy is intensity modulated.
Claim 6
Dependent Claim
23 words
Apparatus as set forth in claim 1, wherein said sensor element has an elongated cylindrical body having a superficies comprising said boundary surface.
Claim 7
Dependent Claim
15 words
Apparatus as set forth in claim 5, wherein said sensor element is an optical fiber.
Claim 8
Dependent Claim
23 words
Apparatus as set forth in claim 1 wherein said sensor element has a plate-shaped body having a major surface comprising said boundary surface.
Claim 9
Dependent Claim
127 words
Apparatus as set forth in claim 1, wherein said test medium is a fluid, and wherein said predetermined characteristic of said test medium is the height of said fluid in a container, wherein said comparison medium which is optically less dense than said fluid, and less dense than said refractive medium of said sensor element, extends over said fluid in said container, wherein said sensor element has a light transmissive boundary surface having a first part immersed in said fluid, and a second part immersed in said comparison medium, wherein said secondary energy receiving means includes a photoreceiver responsive to the intensity of secondary light arranged in proximity to said second part of said boundary surface, and wherein said source of primary energy is a light source.
Claim 10
Dependent Claim
21 words
Apparatus as set forth in claim 8, wherein said fluid is optically denser than said refracting medium of said sensor element.
Claim 11
Dependent Claim
22 words
Apparatus as set forth in claim 1, wherein said test medium is optically denser than said refracting medium of said sensor element.
Claim 12
Dependent Claim
13 words
Apparatus as set forth in claim 1, wherein said particles are luminescent particles.
Claim 13
Dependent Claim
13 words
Apparatus as set forth in claim 11, wherein said luminescent particles are fluorescent.
Claim 14
Dependent Claim
12 words
Apparatus as set forth in claim 11, wherein said particles are phosphorescent.
Claim 15
Dependent Claim
17 words
Apparatus as set forth in claim 12, wherein said source of primary energy is a luminescent diode.
Claim 16
Dependent Claim
68 words
Apparatus as set forth in claim 1 wherein said sensor element is an elongated body having a predetermined length and a first and second end face extending in a direction perpendicular to said predetermined length; and wherein said source of primary energy is a light source arranged at said first end face and said secondary energy receiving means is a photoelectric receiver arranged at said second end face.
Claim 17
Dependent Claim
54 words
Apparatus as set forth in claim 1 wherein said sensor element is an elongated body having a predetermined length and a major surface including said predetermined length, said major surface having a entry area for transmitting light; and wherein said source of primary energy is a light source emitting light toward said entry area.
Claim 18
Dependent Claim
16 words
Apparatus as set forth in claim 1, wherein said secondary energy receiving means comprises a photoreceiver.
Claim 19
Dependent Claim
18 words
Apparatus as set forth in claim 17, further comprising photoconducting means connecting said photoreceiver to said output location.
Claim 20
Dependent Claim
18 words
Apparatus as set forth in claim 1, wherein said refracting medium of said sensor element is light transmissive.
Claim 21
Dependent Claim
14 words
Apparatus as set forth in claim 19, wherein said light transmissive medium is glass.
Claim 22
Dependent Claim
14 words
Apparatus as set, forth in claim 19, wherein said light transmissive medium is plastic.
Claim 23
Dependent Claim
19 words
Apparatus as set forth in claim 19, wherein said light transmissive medium is a tube filled with a fluid.
Claim 24
Dependent Claim
17 words
Apparatus as set forth in claim 19, wherein said light transmissive medium is a gas-filled cylindrical tube.
Claim 25
Dependent Claim
80 words
Apparatus as set forth in claim 1, wherein said test medium comprises a plurality of keys arranged along the length of said sensor element at predetermined distances from one another, made of an optically denser material than said refracting medium of sensor element and arranged to abut said boundary surface when depressed; wherein said sensor element has a first and second end face; and wherein said secondary energy receiving means comprises a photoreceiver arranged at one of said end faces.
Claim 26
Dependent Claim
68 words
Apparatus as set forth in claim 1, wherein said sensor element is an elongated body having a predetermined length, a major surface including said predetermined length, and a first and second end face extending in the direction perpendicular to said predetermined length; and wherein said output location is on said major surface and said source of primary energy is a light source arranged at said first end face.
Claim 27
Dependent Claim
56 words
Apparatus as set forth in claim 1, wherein said sensor element is an elongated body having a predetermined length, and a first and second end face extending in a direction substantially perpendicular to said predetermined length; and wherein said source of primary energy and said secondary energy receiving means are coupled to said first end face.
Claim 28
Dependent Claim
26 words
Apparatus as set forth in claim 26, wherein said source of primary energy is a light source; and wherein said second end face is light transmissive.
Claim 29
Dependent Claim
25 words
Apparatus as set forth in claim 1, wherein said predetermined index of refraction of said sensor element varies as a function of a physical parameter.
Claim 30
Dependent Claim
15 words
Apparatus as set forth in claim 28, wherein said physical parameter is a pressure change.
Claim 31
Dependent Claim
15 words
Apparatus as set forth in claim 28, wherein said physical parameter is a temperature change.
Claim 32
Dependent Claim
20 words
Apparatus as set forth in claim 28, wherein said physical parameter is a change in concentration of a dissolved substance.
Claim 33
Dependent Claim
65 words
Apparatus as set forth in claim 1, wherein said predetermined characteristic of said test medium is the index of refraction of a liquid or a gas and wherein said sensor element is at least partly immersed in said liquid or said gas and has an index of refraction adapted to be varied in correspondence to the index of refraction of said liquid or said gas.
Claim 34
Dependent Claim
26 words
Apparatus as set forth in claim 32, wherein said refracting medium of said sensor element is a solution having a controllable concentration of the dissolved substance.
Claim 35
Dependent Claim
22 words
Apparatus as set forth in claim 32, wherein said refracting medium of said sensor element comprises a gas having an adjustable pressure.
Claim 36
Dependent Claim
25 words
Apparatus as set forth in claim 32, wherein said sensor element is a solid having a refractive index variable as a function of applied pressure.
Claim 37
Dependent Claim
38 words
Apparatus as set forth in claim 32, wherein said sensor element has a refractive index increasing along the length of said sensor element and matching said refractive index of said fluid or gas in at least one location.
References Cited (Backward Citations)
US4443699A
Cited
US4569570A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-03-16 | 1990-09-15 | 1991-03-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-03-16 | 1994-09-15 | 1995-03-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-03-16 | 1998-09-15 | 1999-03-17 | $7700.00 | Window Closed / Lapsed |