Patent US802770A successfully refreshed from Google Patents.
Patent US3636360A successfully refreshed from Google Patents.
US3636360A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for detection of liquid level in transparent tube comprising photocell located to receive light which has been totally reflected
Assignee: Hitachi Ltd
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Filing: 1969-05-12
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Granted: 1972-01-18
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Expires: 1989-05-12
Abstract
Abstract A method for photoelectrically detecting a liquid level by projecting a light beam to a transparent tube communicating with a pressure liquid tank and detecting the redirected light beam, utilizing the difference of relative refractivity at the inner wall of the tube when liquid fills the tube and when not, and the apparatus. Means for receiving the light beam redirected from the tube is so disposed as to receive the light beam only when the tube is empty, or the liquid is lower than the detector.
Inventors
- 👤 Asao Oishi
- 👤 Takashi Yabuki
- 👤 Kazuo Moriguti
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 16:44
CPC Classifications
G; G01; G01F; G01F23/00; G01F23/22; G01F23/28; G01F23/284; G01F23/292; G01F23/2921
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
146 words
An apparatus for photoelectrically detecting a liquid level in a pressure vessel comprising: a transparent tube extending along the outside of said pressure vessel from a point adjacent the bottom thereof to a point beyond the highest liquid level and being connected at both ends with the inside of said vessel, means for projecting a light beam at said transparent tube, and means for receiving the light beam reflected by the surface of said transparent tube, said means including a photosensitive element which is located at a position to receive only the light beam which is totally reflected by said surface, wherein said projecting means is disposed so that the inner wall of said tube totally reflects the light rays from said projecting means through the tube wall when it is disposed in air and mainly refracts the light rays when it is disposed in liquid.
Claim 2
Independent Claim
146 words
An apparatus for photoelectrically detecting a liquid level in a pressure vessel comprising: a transparent tube extending along the outside of said pressure vessel from a point adjacent the bottom thereof to a point beyond the highest liquid level and being connected at both ends with the inside of said vessel, means for projecting a light beam at said transparent tube, and means for receiving the light beam reflected by the surface of said transparent tube, said means including a photosensitive element which is located at a position to receive only the light beam which is totally reflected by said surface, wherein said projecting means is disposed so that the inner wall of said tube totally reflects the light rays from said projecting means through the tube wall when it is disposed in air and mainly refracts the light rays when it is disposed in liquid.
Claim 3
Independent Claim
143 words
An apparatus for photoelectrically detecting a liquid level in a pressure vessel comprising: a transparent tube extending along the outside of said pressure vessel from a point adjacent the bottom thereof to a point beyond the highest liquid level and being connected at both ends with the inside of said vessel, means for projecting a light beam at said transparent tube, a transparent solid plate disposed in said tube with one of its surfaces at an angle to said beam, said plate being made of a material having a refractive index substantially equal to that of the liquid whose level is to be detected, and means for receiving the light beam reflected by the surface of said plate, said means including a photosensitive element which is located at a position to receive only the light beam which is totally reflected by said surface.
Claim 4
Independent Claim
143 words
An apparatus for photoelectrically detecting a liquid level in a pressure vessel comprising: a transparent tube extending along the outside of said pressure vessel from a point adjacent the bottom thereof to a point beyond the highest liquid level and being connected at both ends with the inside of said vessel, means for projecting a light beam at said transparent tube, a transparent solid plate disposed in said tube with one of its surfaces at an angle to said beam, said plate being made of a material having a refractive index substantially equal to that of the liquid whose level is to be detected, and means for receiving the light beam reflected by the surface of said plate, said means including a photosensitive element which is located at a position to receive only the light beam which is totally reflected by said surface.
Claim 5
Independent Claim
154 words
An apparatus for photoelectrically detecting a liquid level in a pressure vessel comprising: a transparent tube extending along the outside of said pressure vessel from a point adjacent the bottom thereof to a point beyond the highest liquid level and being connected at both ends with the inside of said vessel, means for projecting a light beam at said transparent tube, and means for receiving the light beam reflected by the surface of said transparent tube, said means including a photosensitive element which is located at a position to receive only the light beam which is totally reflected by said surface, wherein said tube has a cylindrical cross section and said projecting means is positioned with respect to said tube so that said beam will be totally reflected from the inner surface of said tube closest to said projecting means only when the level of said liquid is below the plane of said beam.
Claim 6
Independent Claim
154 words
An apparatus for photoelectrically detecting a liquid level in a pressure vessel comprising: a transparent tube extending along the outside of said pressure vessel from a point adjacent the bottom thereof to a point beyond the highest liquid level and being connected at both ends with the inside of said vessel, means for projecting a light beam at said transparent tube, and means for receiving the light beam reflected by the surface of said transparent tube, said means including a photosensitive element which is located at a position to receive only the light beam which is totally reflected by said surface, wherein said tube has a cylindrical cross section and said projecting means is positioned with respect to said tube so that said beam will be totally reflected from the inner surface of said tube closest to said projecting means only when the level of said liquid is below the plane of said beam.
Claim 7
Independent Claim
165 words
An apparatus for photoelectrically detecting a liquid level in a pressure vessel comprising: a transparent cylindrical tube positioned along the outside of said pressure vessel from a point adjacent the bottom of said vessel to a point adjacent the top thereof and being connected at both ends with the inside of said vessel, light projecting means for projecting a concentrated beam of light at a point on the inner surface of said transparent tube on the side thereof adjacent said light projecting means, said light projecting means being positioned with respect to said transparent tube so that said beam intercepts the inner surface of said tube at said point at an angle greater than the critical angle for air within the tube at said point and at an angle less than the critical angle for liquid in the tube at said point, and light detecting means positioned in line with the path of total reflection of said beam at said point for detecting said beam.
Claim 8
Independent Claim
165 words
An apparatus for photoelectrically detecting a liquid level in a pressure vessel comprising: a transparent cylindrical tube positioned along the outside of said pressure vessel from a point adjacent the bottom of said vessel to a point adjacent the top thereof and being connected at both ends with the inside of said vessel, light projecting means for projecting a concentrated beam of light at a point on the inner surface of said transparent tube on the side thereof adjacent said light projecting means, said light projecting means being positioned with respect to said transparent tube so that said beam intercepts the inner surface of said tube at said point at an angle greater than the critical angle for air within the tube at said point and at an angle less than the critical angle for liquid in the tube at said point, and light detecting means positioned in line with the path of total reflection of said beam at said point for detecting said beam.
Claim 9
Dependent Claim
35 words
An apparatus according to claim 4, wherein said transparent cylindrical tube is made of a material having a refractive index approximately equal to the refractive index of the liquid whose level is to be detected.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-01-17 | 1975-07-19 | 1976-01-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-01-17 | 1979-07-19 | 1980-01-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-01-17 | 1983-07-19 | 1984-01-18 | $7700.00 | Window Closed / Lapsed |