US3671746A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Stable, low level radiation monitor
Assignee: Allis Chalmers Corp
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Filing: 1970-06-02
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Granted: 1972-06-20
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Expires: 1990-06-02
Abstract
Abstract A radiation monitor has a low-loss integrating capacitor connected to be charged by the output of a radiation sensor, a high input impedance operational amplifier operating in the inverting mode connected across the integrating capacitor, and a reference voltage source applied to the noninverting input, whereby the operational amplifier is initially in positive saturation and switches to negative saturation when the charge across the capacitor equal the reference voltage. Means responsive to the negative saturation output of the operational amplifier are provided to discharge the integrating capacitor and to generate a pulse, and a pulse counter gives an indication of total radiation received by the sensor. A second high input impedance operational amplifier operating in the inverting mode has its inverting input connected to one electrode of the integrating capacitor and holds it at zero potential, and a current meter driven by the output of the second operational amplifier provides an analog indication of the current from the radiation sensor flowing through the integrating capacitor and is calibrated in roentgens per minute received by the sensor.
Inventors
- 👤 Tom N Thiele
- 👤 Lester O Gerlach
- 👤 Thomas P Gilmore
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 09:13
CPC Classifications
G; G01; G01T; G01T1/00; G01T1/16; G01T1/17
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
129 words
A current measuring circuit having high stability and minimum drift comprising, in combination, a source of current of very low magnitude, a low-loss integrating capacitor connected to be charged by said current from said source, a high input impedance operational amplifier having one input coupled to said integrating capacitor, means for applying a reference voltage to the other input of said operational amplifier, whereby said operational amplifier is initially in saturation of one polarity and is forced into saturation of the opposite polarity when the voltage across said integrating capacitor builds up to said reference voltage, means responsive to said opposite polarity saturation output of said operational amplifier for discHarging said integrating capacitor and for generating an electrical pulse, and a pulse counter coupled to said pulse generating means.
Claim 2
Dependent Claim
129 words
A current measuring circuit having high stability and minimum drift comprising, in combination, a source of current of very low magnitude, a low-loss integrating capacitor connected to be charged by said current from said source, a high input impedance operational amplifier having one input coupled to said integrating capacitor, means for applying a reference voltage to the other input of said operational amplifier, whereby said operational amplifier is initially in saturation of one polarity and is forced into saturation of the opposite polarity when the voltage across said integrating capacitor builds up to said reference voltage, means responsive to said opposite polarity saturation output of said operational amplifier for discHarging said integrating capacitor and for generating an electrical pulse, and a pulse counter coupled to said pulse generating means.
Claim 3
Dependent Claim
77 words
A measuring circuit in accordance with claim 1 and including a second high input impedance operational amplifier connected in the inverting mode and having its inverting input coupled to one electrode of said integrating capacitor, whereby said one electrode of said integrating capacitor is maintained at zero potential, and electroresponsive indicating means coupled to the output of said second operational amplifier for providing an analog indication of the current from said source flowing through said integrating capacitor.
Claim 4
Dependent Claim
62 words
A measuring circuit in accordance with claim 2 wherein said second operational amplifier has a feedback resistance between its output and its inverting input and including a resistor connected between a point intermediate the ends of said feedback resistance and ground, whereby said current passing through said integrating capacitor flows through a portion of said feedback resistance and said resistor to ground.
Claim 5
Dependent Claim
53 words
A measuring circuit in accordance with claim 3 and including a triaxial shielded cable having a central conductor coupling said current source to said integrating capacitor and concentric radially inner and radially outer shields surrounding said conductor and wherein said inner shield is coupled to said inverting input of said second operational amplifier.
Claim 6
Dependent Claim
128 words
A radiation monitor comprising, in combination, a radiation sensor, a low-loss integrating capacitor connected to be charged by the output of said sensor, a high input impedance operational amplifier having its inverting input coupled to said integrating capacitor, a reference voltage source connected to the noninverting input of said operational amplifier, whereby said operational amplifier is initially in positive saturation and switches to negative saturation when the charge on said capacitor builds up to a predetermined voltage, means coupled to the output of said operational amplifier for discharging said integrating capacitor when said operational amplifier switches to negative saturation, a pulse counter, and means having its output coupled to said pulse counter and responsive to the negative saturation output of said operational amplifier for generating an output pulse.
Claim 7
Dependent Claim
128 words
A radiation monitor comprising, in combination, a radiation sensor, a low-loss integrating capacitor connected to be charged by the output of said sensor, a high input impedance operational amplifier having its inverting input coupled to said integrating capacitor, a reference voltage source connected to the noninverting input of said operational amplifier, whereby said operational amplifier is initially in positive saturation and switches to negative saturation when the charge on said capacitor builds up to a predetermined voltage, means coupled to the output of said operational amplifier for discharging said integrating capacitor when said operational amplifier switches to negative saturation, a pulse counter, and means having its output coupled to said pulse counter and responsive to the negative saturation output of said operational amplifier for generating an output pulse.
Claim 8
Dependent Claim
71 words
A radiation monitor in accordance with claim 5 and including a second high input impedance operational amplifier connected in the inverting mode and having its inverting input coupled to one electrode of said integrating capacitor, whereby said one electrode is held at zero potential, and indicating current meter means driven by the output of said second operational amplifier for providing an analog indication of the input current from said radiation sensor.
Claim 9
Dependent Claim
62 words
A radiation monitor in accordance with claim 6 wherein said second operational amplifier has a feedback resistance between its output and its inverting input and including a resistor connected between a point intermediate the ends of said feedback resistance and ground, whereby said current passing through said integrating capacitor flows through a portion of said feedback resistance and said resistor to ground.
Claim 10
Dependent Claim
140 words
A radiation monitor comprising, in combination, a radiation sensor, a low-loss integrating capacitor connected to be charged by the output of said radiation sensor, means including a first high input impedance operational amplifier having an input connected across said integrating capacitor for indicating the charge built up across said integrating capacitor as a measure of total radiation received by said sensor, a second high input impedance operational amplifier connected in the inverting mode with a feedback resistance between the output and the inverting input thereof, said inverting input of said second operational amplifier being coupled to one electrode of said integrating capacitor, whereby said one electrode is maintained at zero volts, and electroresponsive indicating means coupled to the output of second operational amplifier for providing an analog indication of the current from said radiation sensor flowing through said integrating capacitor.
Claim 11
Dependent Claim
140 words
A radiation monitor comprising, in combination, a radiation sensor, a low-loss integrating capacitor connected to be charged by the output of said radiation sensor, means including a first high input impedance operational amplifier having an input connected across said integrating capacitor for indicating the charge built up across said integrating capacitor as a measure of total radiation received by said sensor, a second high input impedance operational amplifier connected in the inverting mode with a feedback resistance between the output and the inverting input thereof, said inverting input of said second operational amplifier being coupled to one electrode of said integrating capacitor, whereby said one electrode is maintained at zero volts, and electroresponsive indicating means coupled to the output of second operational amplifier for providing an analog indication of the current from said radiation sensor flowing through said integrating capacitor.
Claim 12
Dependent Claim
46 words
A radiation monitor in accordance with claim 8 and including a resistor connected between a point intermediate the ends of said feedback resistance and ground, whereby said current passing through said integrating capacitor flows through a portion of said feedback resistance and said resistor to ground.
Claim 13
Dependent Claim
77 words
A radiation monitor in accordance with claim 8 wherein said means for indicating the charge built up across said capacitor includes means coupled to the output of said first operational amplifier for providing an output signal in response to a predetermined voltage across said integrating capacitor, means responsive to said output signal for discharging said integrating capacitor, means responsive to said output signal for generating a pulse, and a pulse counter coupled to said pulse generating means.
Claim 14
Dependent Claim
112 words
A radiation monitor in accordance with claim 9 wherein said first operational amplifier has its inverting input coupled to said integrating capacitor and said means for indicating the charge built up across said integrating capacitor includes means for applying a reference voltage to the noninverting input of said first operational amplifier, whereby said first operational amplifier is initially in positive saturation and is forced into negative saturation when the voltage across said integrating capacitor builds up to said reference voltage, means responsive to the negative saturation output of said first operational amplifier for generating a pulse and for discharging said integrating capacitor, and a pulse counter coupled to said pulse generating means.
Claim 15
Dependent Claim
47 words
A radiation monitor in accordance with claim 11 and including a triaxial cable having an inner and an outer shield and coupling said radiation sensor to said integrating capacitor, said inner shield of said triaxial cable being coupled to said inverting input of said second operational amplifier.
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) | 1975-06-20 | 1975-12-20 | 1976-06-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-06-20 | 1979-12-20 | 1980-06-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-06-20 | 1983-12-20 | 1984-06-20 | $7700.00 | Window Closed / Lapsed |