US3970928A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrical apparatus for the calibration of equipment used in the measurement of particle volume
Assignee: Max-Planck-Gesellschaft zur Förderung der Wissenschaften eV
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Filing: 1974-12-17
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Granted: 1976-07-20
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Expires: 1994-12-17
Abstract
Abstract Calibration apparatus for use with particle volume measuring equipment us the Coulter process, which detects and analyzes the voltage pulses produced by particles passing a narrow aperture in which an electric field is maintained. The calibration apparatus includes a calibration pulse generator with pulse-shaping circuitry which produces a sequence of calibration pulses, approximately trapezoidal in shape, which are introduced into the particle measurement path, in series with the measurement aperture traversed by the particles. The generator includes precision attenuation resistors for varying the amplitude of the calibration pulses. The apparatus also provides for adjusting and maintaining a constant current through the measurement aperture and for amplifying the pulses produced by particles passing through the aperture whose amplitude is compared with the amplitude of the calibration pulses.
Inventors
- 👤 Volker Kachel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 20:19
CPC Classifications
G; G01; G01N; G01N15/00; G01N15/10; G01N15/1031; G01N15/12; G01N15/131; G01N15/132
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
244 words
In an electrical apparatus for calibration of measurement equipment for measuring the volume of particles, which includes two chambers filled with liquid electrolyte which communicate through a measurement aperture, and which further includes two electrodes located on opposite sides of the aperture, by which a current can be passed through the aperture, and which further includes means for introducing particles into the first of said two chambers, said particles passing through said measurement aperture, thereby generating voltage pulses across the electrodes, said apparatus further including a processing and analysis unit for processing and analyzing said voltage pulses, and including means for producing calibration voltage pulses which are used by said processing and analyzing unit to associate a certain particle volume with a certain voltage pulse amplitude, the improvement comprising: a resistor which is positioned in the electrical path in series with said measurement aperture, said resistor having an ohmic resistance which is small with respect to the ohmic resistance of said measurement aperture; and a calibration pulse generator, for producing calibration voltage pulses of adjustable amplitude, said calibration voltage pulses being introduced into the electrical path formed between said resistor and said measurement aperture, thereby applying the calibration voltage pulses essentially across the electrodes, said calibration pulses also being fed to the processing and analyzing unit, in which a numerical volume derived by calculation and theory from said calibration voltage pulses is associated with the voltage pulses received by said processing and analysis unit.
Claim 2
Dependent Claim
244 words
In an electrical apparatus for calibration of measurement equipment for measuring the volume of particles, which includes two chambers filled with liquid electrolyte which communicate through a measurement aperture, and which further includes two electrodes located on opposite sides of the aperture, by which a current can be passed through the aperture, and which further includes means for introducing particles into the first of said two chambers, said particles passing through said measurement aperture, thereby generating voltage pulses across the electrodes, said apparatus further including a processing and analysis unit for processing and analyzing said voltage pulses, and including means for producing calibration voltage pulses which are used by said processing and analyzing unit to associate a certain particle volume with a certain voltage pulse amplitude, the improvement comprising: a resistor which is positioned in the electrical path in series with said measurement aperture, said resistor having an ohmic resistance which is small with respect to the ohmic resistance of said measurement aperture; and a calibration pulse generator, for producing calibration voltage pulses of adjustable amplitude, said calibration voltage pulses being introduced into the electrical path formed between said resistor and said measurement aperture, thereby applying the calibration voltage pulses essentially across the electrodes, said calibration pulses also being fed to the processing and analyzing unit, in which a numerical volume derived by calculation and theory from said calibration voltage pulses is associated with the voltage pulses received by said processing and analysis unit.
Claim 3
Dependent Claim
35 words
An electrical apparatus as defined in claim 1, the improvement further comprising: at least one current-sensitive amplifier for amplifying said calibration voltage pulses after their passage over the electrical path formed between said two electrodes.
Claim 4
Dependent Claim
47 words
An improved apparatus as defined in claim 1, wherein said calibration pulse generator includes a plurality of resistors, selective ones of said resistors being capable of being connected in series with the output of said calibration pulse generator to adjust the amplitude of said calibration voltage pulses.
Claim 5
Dependent Claim
53 words
An improved apparatus as defined in claim 1, wherein said calibration pulse generator further includes: an oscillator for producing rectangular pulses; and pulse-shaping circuitry, for transforming said rectangular pulses into calibration pulses whose shape conforms approximately to the shape of the voltage pulses which occur when a particle passes through said measurement aperture.
Claim 6
Dependent Claim
136 words
An apparatus as defined in claim 4, wherein said pulse-shaping circuitry includes: a first constant current source, switched on by one of said rectangular pulses; a capacitor, capable of being charged by said first constant current source; voltage limiting means, for limiting the voltage impressed on said capacitor by charging; a second constant current source, connected to said capacitor, for discharging said capacitor when said rectangular pulse has turned off said first constant current source; a first diode, connected in series with said second constant current source; and a third constant current source, connected in series with said first diode; whereby, after said capacitor has discharged to zero potential, said first diode becomes conductive and the current delivered by said second constant current source flows through said first diode and through said third constant current source.
Claim 7
Dependent Claim
85 words
An apparatus as defined in claim 5, said pulse-shaping circuitry further including: a second diode, connected to the junction of said first diode and said third constant current source and to the side of said capacitor connected to zero potential, for compensating the voltage drop across said first diode with respect to the side of said capacitor connected to said first constant current source and produced by the current flowing through said second and said third constant current sources after the discharge of said capacitor.
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) | 1979-07-20 | 1980-01-19 | 1980-07-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-07-20 | 1984-01-19 | 1984-07-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-07-20 | 1988-01-19 | 1988-07-20 | $7700.00 | Window Closed / Lapsed |