US3648047A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Sensitivity control for mass spectrometer
Assignee: Applied Biosystems Inc
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Filing: 1970-07-13
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Granted: 1972-03-07
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Expires: 1990-07-13
Abstract
Abstract In a mass spectrometer wherein gases of a mixture are ionized and respective ion beams are directed to collector plates or cups to generate proportional signals for determining the relative amounts of the several gases in the mixture, the sensitivity of the collector cup signals is maintained by adjusting the ionizing power supply as required to maintain the total of the signals from the collector plates or cups substantially equal to a reference signal. The total of the collector signals are compared with the reference signal by a summing amplifier. When the compared signals differ from a predetermined relation (e.g., equality) a proportional output signal is generated and applied to power control means to vary the level of power applied to ionize the mixture, and hence the levels of the collector signals, until the total of the collector signals is in said predetermined relation to the reference signal. Resistors associated with the collector plates or cups and with the reference signal source are selected so that the total of the collector signals and the reference signal are in said predetermined relation when the ion species collected are related to the gas species of interest.
Inventors
- 👤 Bliss M Bushman
- 👤 Wayne J Whistler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 22:12
CPC Classifications
H; H01; H01J; H01J49/00; H01J49/02; H01J49/10; H01J49/14
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
232 words
A mass spectrometer comprising an electrically actuated source of ions of the gases contained in a sample mixture, a plurality of ion collectors for receiving, respectively, ions of the gases in the mixture, said collectors discharging ions received thereby and producing electric output signals proportional to the number of ions received, means for directing ions from the source to the respective collectors, means for measuring the electric signals from the collectors as means for measuring the relative amounts of the respective gases in the sample mixture, and means for maintaining the sensitivity of the spectrometer comprising electrically actuated control means controlling the number of ions supplied to the collectors from the source, circuit means associated with the collectors for adjusting their output signals to be equal at unit partial pressures of the gases whose ions are received, respectively, at the collectors, signal summing means connected to receive the electric signals from the collectors, and means producing a reference signal from a reference voltage source and connected to apply the reference signal to the signal summing means, said signal summing means producing an output signal proportional to variations of the total of the signals of the collectors from a predetermined relation to the reference signal, and being connected to apply its output signal to said control means to vary the number of ions supplied to the collectors in proportion to said output signal.
Claim 2
Dependent Claim
232 words
A mass spectrometer comprising an electrically actuated source of ions of the gases contained in a sample mixture, a plurality of ion collectors for receiving, respectively, ions of the gases in the mixture, said collectors discharging ions received thereby and producing electric output signals proportional to the number of ions received, means for directing ions from the source to the respective collectors, means for measuring the electric signals from the collectors as means for measuring the relative amounts of the respective gases in the sample mixture, and means for maintaining the sensitivity of the spectrometer comprising electrically actuated control means controlling the number of ions supplied to the collectors from the source, circuit means associated with the collectors for adjusting their output signals to be equal at unit partial pressures of the gases whose ions are received, respectively, at the collectors, signal summing means connected to receive the electric signals from the collectors, and means producing a reference signal from a reference voltage source and connected to apply the reference signal to the signal summing means, said signal summing means producing an output signal proportional to variations of the total of the signals of the collectors from a predetermined relation to the reference signal, and being connected to apply its output signal to said control means to vary the number of ions supplied to the collectors in proportion to said output signal.
Claim 3
Dependent Claim
127 words
The mass spectrometer of claim 1 including resistance means respectively between each of the ion collectors and the signal summing means and between the reference signal producing means and the signal summing means, the resistance means associated with the respective collectors being selected so that the signal currents produced per unit of partial pressure of the gases of the mixture by the respective collectors are equal to each other at the outputs of these resistance means, the resistance means associated with the reference voltage signal producing means being selected so that the current received therefrom is in a predetermined relation to the total of currents received from the resistance means associated with the collectors when the gas mixture is one containing each gas whose ions are collected.
Claim 4
Dependent Claim
22 words
The mass spectrometer of claim 2 in which the reference voltage source comprises a variable resistor coupled to a source of voltage.
Claim 5
Dependent Claim
36 words
The mass spectrometer of claim 1 in which said reference voltage source is a total pressure transducer connected into said gas mixture and producing a reference voltage proportional to the total pressure of the gas mixture.
Claim 6
Dependent Claim
125 words
The mass spectrometer of claim 4 including resistance means respectively between the ion collectors and the signal summing means and between the transducer and the signal summing means, the resistance means associated with the respective collectors being selected so that the optimum signal currents, as produced per unit partial pressure of the respective gases at the collectors by ions of the gases of the mixture and as received from these resistance means, are equal to each other, the resistance means associated with the transdUcer being selected so that the current received therefrom is equal to the total of the signal currents received from the resistance means associated with the collectors when the gas mixture being analyzed is one containing each gas whose ions are collected.
Claim 7
Dependent Claim
77 words
The mass spectrometer of claim 1 including means for ionizing a sample gas mixture comprising an electron beam generator having a cathode and an anode connected to a power source for producing a beam of electrons therebetween for ionizing gases in the proximity of the beam, said control means being coupled to the electron beam generator for adjusting the intensity of said electron beam to be in proportion to an output signal from the signal summing means.
Claim 8
Dependent Claim
25 words
The mass spectrometer of claim 6 in which said control means is connected to adjust the power input to the cathode from said power source.
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) | 1975-03-07 | 1975-09-06 | 1976-03-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-03-07 | 1979-09-06 | 1980-03-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-03-07 | 1983-09-06 | 1984-03-07 | $7700.00 | Window Closed / Lapsed |