US3768084A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Particle counter having a clog and bubble alarm
Assignee: Becton Dickinson and Co
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Filing: 1972-07-14
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Granted: 1973-10-23
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Expires: 1992-07-14
Abstract
Abstract A fluid containing disbursed particles having a conductivity substantially different than the fluid is pumped through an aperture. A pair of electrodes are mounted so that one electrode is on each side of said aperture and an rf signal is imposed upon the electrodes to develop a voltage across the fluid passing through the aperture. The rf signal is modulated by the conductivity of the fluid instantaneously passing through the aperture so that when a high resistance particle passes through the aperture, the rf signal intensity increases in relationship to the rf signal intensity when fluid is passing through the aperture. The rf signal is then detected, filtered and amplified to provide pulses corresponding to the particles passing through the aperture. Means are provided for counting the pulses and for providing a readout indicating the number of particles contained in a unit volume of the fluid. A clog alarm driver circuit is connected to receive the filtered rf signal and in response to a constant high level filtered signal provides an output to an alarm for indicating a clogged aperture. The amplified signal is directed to an amplifier clipper which further amplifies the signal and establishes a base line at 8 volts DC with pulses having an amplitude of approximately 4 to 6 volts. The presence of bubbles at the aperture causes an erratic signal which appears as base line noise and includes excursions below the 8 volt DC base line output. These excursions intermittently turn on a transistor which provides an output signal to a bubble alarm driver which in response thereto provides an output to the previously-mentioned alarm. A continuous alarm indicates a clogged aperture while an intermittent alarm indicates the formation of bubbles at the aperture.
Inventors
- 👤 J Haynes
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 13:22
CPC Classifications
G; G01; G01N; G01N15/00; G01N15/10; G01N15/1031; G01N15/12; G01N15/131; G01N15/132; A; A61; A61M; A61M5/00; A61M5/36; A61M5/365
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
232 words
An instrument for counting particles suspended in a fluid medium, wherein the fluid medium and the particles have different conductivities, comprising: an aperture; means for passing the fluid through the aperture; means for applying an electrical signal across the aperture; detecting means for detecting changes in the electrical signal level across the aperture and for providing an output having pulses corresponding to the changes in the electrical signal which result from a change in impedance across the aperture as particles pass through the aperture; means for counting the pulses from the detecting means that exceed a predetermined level and for providing an indication corresponding to the number of particles per unit volume of the fluid; clog detecting means responsive to the output from the detecting means for sensing when the detecting means provides a constant output exceeding a predetermined level resulting from a clogged aperture and for providing a steady state signal output in response thereto; bubble detecting means responsive to the output from the detecting means for detecting erratic and rapidly changing pulses which result from the formation of bubbles adjacent the aperture and for providing an intermittent signal output in response thereto; and indicator means, responsive to the signal outputs from the clog and bubble detecting means, for providing a con-stant indication when a clogged aperture exists and for providing an intermittent indication when bubbles are formed adjacent the aperture.
Claim 2
Dependent Claim
232 words
An instrument for counting particles suspended in a fluid medium, wherein the fluid medium and the particles have different conductivities, comprising: an aperture; means for passing the fluid through the aperture; means for applying an electrical signal across the aperture; detecting means for detecting changes in the electrical signal level across the aperture and for providing an output having pulses corresponding to the changes in the electrical signal which result from a change in impedance across the aperture as particles pass through the aperture; means for counting the pulses from the detecting means that exceed a predetermined level and for providing an indication corresponding to the number of particles per unit volume of the fluid; clog detecting means responsive to the output from the detecting means for sensing when the detecting means provides a constant output exceeding a predetermined level resulting from a clogged aperture and for providing a steady state signal output in response thereto; bubble detecting means responsive to the output from the detecting means for detecting erratic and rapidly changing pulses which result from the formation of bubbles adjacent the aperture and for providing an intermittent signal output in response thereto; and indicator means, responsive to the signal outputs from the clog and bubble detecting means, for providing a con-stant indication when a clogged aperture exists and for providing an intermittent indication when bubbles are formed adjacent the aperture.
Claim 3
Dependent Claim
33 words
An instrument as described in claim 1, wherein the clog detecting means comprises a driver circuIt biased to provide a signal output when the output of the detecting means exceeds a predetermined level.
Claim 4
Dependent Claim
72 words
An instrument as described in claim 1, wherein the bubble detecting means comprises: an amplifier clipper circuit for providing an output signal corresponding to the output of the detecting means but biased at a DC level; and means for detecting when the amplifier clipper circuit output signal drops below the DC bias level as a result of errotic and rapidly changing pulses and for providing the intermittent signal output in response thereto.
Claim 5
Dependent Claim
67 words
An instrument as described in claim 3, wherein the amplifier clipper circuit comprises: an operational amplifier having a first input for receiving the output from the detecting means; a biasing circuit connected to the first input for establishing a DC bias level; and a feedback loop connecting the amplifier output to a second input, so that the amplifier provides an output signal biased at a DC level.
Claim 6
Dependent Claim
60 words
An instrument as described in claim 4, wherein the means for detecting when the output signal drops below the DC bias level includes a transistor having the base to emitter junction connected between the output and the second input of the operational amplifier so that the transistor is turned on when the output signal drops below the DC bias level.
Claim 7
Dependent Claim
205 words
In a particle counting apparatus of the type, wherein a fluid medium containing particles having a conductivity different from the fluid is passed through an aperture and electrodes positioned at each side of the aperture are energized to develop a signal corresponding to the impedance across the aperture so that the particles cause signal changes as they pass through the aperture and the changes are detected and counted to provide a readout corresponding to the number of particles per unit volume of the fluid medium, the improvement comprising: clog detecting means for detecting a steady state electrical signal across the electrodes that exceeds a predetermined level and for providing a constant output in response thereto; bubble detecting means for detecting erratic signal changes across the electrodes and for providing an intermittent output in response thereto; and indicator means connected to the last two mentioned means and responsive to the outputs therefrom for providing a constant indication in response to the output of the first mentioned means and an intermittent indication in response to the output of the second mentioned means so that the constant indication is provided when an aperture clog exists and an intermittent indication is provided when bubbles are formed adjacent the aperture.
Claim 8
Dependent Claim
205 words
In a particle counting apparatus of the type, wherein a fluid medium containing particles having a conductivity different from the fluid is passed through an aperture and electrodes positioned at each side of the aperture are energized to develop a signal corresponding to the impedance across the aperture so that the particles cause signal changes as they pass through the aperture and the changes are detected and counted to provide a readout corresponding to the number of particles per unit volume of the fluid medium, the improvement comprising: clog detecting means for detecting a steady state electrical signal across the electrodes that exceeds a predetermined level and for providing a constant output in response thereto; bubble detecting means for detecting erratic signal changes across the electrodes and for providing an intermittent output in response thereto; and indicator means connected to the last two mentioned means and responsive to the outputs therefrom for providing a constant indication in response to the output of the first mentioned means and an intermittent indication in response to the output of the second mentioned means so that the constant indication is provided when an aperture clog exists and an intermittent indication is provided when bubbles are formed adjacent the aperture.
Claim 9
Dependent Claim
205 words
An instrument for counting the number of particles per unit volume suspended in a fluid medium, said fluid medium having a conductivity different than the particles, comprising: an aperture; means for passing the fluid through the aperture; means for applying an electronic signal across the aperture; detecting means for detecting changes in the electronic signal level across the aperture and for forming pulses corresponding to the changes which result from an increase in impedance across the aperture as particles pass through the aperture; means for counting the pulses that exceed a predetermined level and for providing an indication corresponding to the number of particles per unit volume of the fluid; a clog alarm driver responsive to the output of the detecting means for providing a steady state output when the aperture is clogged; a bubble detector and alarm driver responsive to the pulses from the detecting means for providing an intermittent output when bubbles are formed adjacent the aperture; and an alarm indicator connected to the output of the clog alarm driver and bubble detector and alarm driver and responsive to the signals therefrom for providing a constant indication when the aperture is clogged and an intermittent indication when bubbles are formed adjacent tHe aperture.
Claim 10
Dependent Claim
205 words
An instrument for counting the number of particles per unit volume suspended in a fluid medium, said fluid medium having a conductivity different than the particles, comprising: an aperture; means for passing the fluid through the aperture; means for applying an electronic signal across the aperture; detecting means for detecting changes in the electronic signal level across the aperture and for forming pulses corresponding to the changes which result from an increase in impedance across the aperture as particles pass through the aperture; means for counting the pulses that exceed a predetermined level and for providing an indication corresponding to the number of particles per unit volume of the fluid; a clog alarm driver responsive to the output of the detecting means for providing a steady state output when the aperture is clogged; a bubble detector and alarm driver responsive to the pulses from the detecting means for providing an intermittent output when bubbles are formed adjacent the aperture; and an alarm indicator connected to the output of the clog alarm driver and bubble detector and alarm driver and responsive to the signals therefrom for providing a constant indication when the aperture is clogged and an intermittent indication when bubbles are formed adjacent tHe aperture.
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) | 1976-10-22 | 1977-04-23 | 1977-10-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-22 | 1981-04-23 | 1981-10-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-22 | 1985-04-23 | 1985-10-23 | $7700.00 | Window Closed / Lapsed |