US4333016A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Liquid presence detector
Assignee: Baxter International Inc
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Filing: 1980-03-06
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Granted: 1982-06-01
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Expires: 2000-03-06
Abstract
Abstract A liquid presence detector having a light-transmissive chamber for the liquid to be detected. A light emitting diode is positioned outside of the chamber for transmitting light through the chamber and a photosensitive transistor is positioned for receiving the light that has been transmitted through the chamber. The light emitting diode is located at a distance from the chamber that is equal to the focal point of a lens that is created by the chamber and liquid when the liquid is present. The photosensitive transistor output voltage is compared with a reference voltage and an output signal is provided in response to a predetermined difference between the detector output voltage and the reference voltage.
Inventors
- 👤 Arnold C. Bilstad
- 👤 Richard I. Brown
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 04:39
CPC Classifications
G; G01; G01F; G01F23/00; G01F23/22; G01F23/28; G01F23/284; G01F23/292; G01F23/2921; A; A61; A61M; A61M1/00; A61M1/36; A61M1/3621; A61M1/3624; A61M1/3672; A61M5/00; A61M5/36; A61M5/365
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
184 words
A liquid presence detector for detecting the absence of fluid in a fluid chamber, comprising: a radiation source positioned outside the chamber for transmitting radiation through the chamber, the magnitude of radiation transmitted through the chamber being dependent on the presence of fluid therein; a radiation detector for receiving radiation transmitted through the chamber and producing an output signal having a level dependent on the magnitude thereof, said detector output signal having a normal operating range extending from a predetermined maximum signal level to a predetermined minimum signal level; first comparison means for comparing the detector output signal level with a first reference signal level to develop an output when said output signal level exceeds a first predetermined threshold level between said maximum and minimum detector output levels; second comparison means for comparing the detector output signal level with a second reference signal level to develop an output when said output level exceeds a second predetermined threshold level above said maximum signal level; and output circuit means responsive to outputs from either said first or second comparison means for providing an alarm output signal.
Claim 2
Dependent Claim
184 words
A liquid presence detector for detecting the absence of fluid in a fluid chamber, comprising: a radiation source positioned outside the chamber for transmitting radiation through the chamber, the magnitude of radiation transmitted through the chamber being dependent on the presence of fluid therein; a radiation detector for receiving radiation transmitted through the chamber and producing an output signal having a level dependent on the magnitude thereof, said detector output signal having a normal operating range extending from a predetermined maximum signal level to a predetermined minimum signal level; first comparison means for comparing the detector output signal level with a first reference signal level to develop an output when said output signal level exceeds a first predetermined threshold level between said maximum and minimum detector output levels; second comparison means for comparing the detector output signal level with a second reference signal level to develop an output when said output level exceeds a second predetermined threshold level above said maximum signal level; and output circuit means responsive to outputs from either said first or second comparison means for providing an alarm output signal.
Claim 3
Dependent Claim
25 words
A liquid presence detector as defined in claim 1 wherein said radiation source comprises a light source and said radiation detector comprises a light detector.
Claim 4
Dependent Claim
33 words
A liquid presence detector as defined in claim 1 wherein said first predetermined threshold level corresponds to the transition of said detector output signal between fluid presence and fluid absence in the chamber.
Claim 5
Dependent Claim
62 words
A liquid presence detector as defined in claim 1 including third comparison means for comparing the detector output signal with a third predetermined reference level to develop an output when said output level falls below a third predetermined threshold level below said minimum detector output level, and wherein said output circuit means is responsive to the output of said third comparison means.
Claim 6
Dependent Claim
239 words
A liquid presence detector for detecting the absence of fluid in a fluid chamber, comprising: a light source positioned outside the chamber for transmitting light through the chamber, the magnitude of light transmitted through the chamber being dependent on the presence of fluid therein; a light detector for receiving light transmitted through the chamber and producing an output signal having a level dependent on the magnitude thereof; said detector output signal having a normal operating range extending from a determined maximum signal level to a predetermined minimum signal level; first comparison means for comparing the detector output signal level with a first reference signal level to develop an output when said output signal level exceeds a first predetermined threshold level between said maximum and minimum detector output levels corresponding to the transition of said detector output signal between fluid presence and fluid absence in the chamber; second comparison means for comparing the detector output signal level with a second reference signal level to develop an output when said output level exceeds a second predetermined threshold level above said maximum signal level; third comparison means for comparing the detector output signal with a third predetermined reference level to develop an output when said output level falls below a third predetermined threshold level below said minimum detector output level; and output circuit means responsive to outputs from either said first, second or third comparison means for providing an alarm output signal.
Claim 7
Dependent Claim
239 words
A liquid presence detector for detecting the absence of fluid in a fluid chamber, comprising: a light source positioned outside the chamber for transmitting light through the chamber, the magnitude of light transmitted through the chamber being dependent on the presence of fluid therein; a light detector for receiving light transmitted through the chamber and producing an output signal having a level dependent on the magnitude thereof; said detector output signal having a normal operating range extending from a determined maximum signal level to a predetermined minimum signal level; first comparison means for comparing the detector output signal level with a first reference signal level to develop an output when said output signal level exceeds a first predetermined threshold level between said maximum and minimum detector output levels corresponding to the transition of said detector output signal between fluid presence and fluid absence in the chamber; second comparison means for comparing the detector output signal level with a second reference signal level to develop an output when said output level exceeds a second predetermined threshold level above said maximum signal level; third comparison means for comparing the detector output signal with a third predetermined reference level to develop an output when said output level falls below a third predetermined threshold level below said minimum detector output level; and output circuit means responsive to outputs from either said first, second or third comparison means for providing an alarm output signal.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-05-31 | 1985-11-30 | 1986-06-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-05-31 | 1989-11-30 | 1990-06-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-05-31 | 1993-11-30 | 1994-06-01 | $7700.00 | Window Closed / Lapsed |