US3729675A
Expired / Lapsed
US
⏱️ 0.0 years remaining
High level non-contacting dynamic voltage follower for voltage measurement of electrostatically charged surfaces
Assignee: Individual
•
Filing: 1970-02-13
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Granted: 1973-04-24
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Expires: 1990-02-13
Abstract
Abstract A wide band voltage follower circuit for voltage measurement of electrostatically charged surfaces through the use of a probe having a capacitor detector arranged in spaced and non-contacting manner with the surface under measurement to detect the unknown surface voltage thereof, the probe having a cable connected to the output of the capacitor detector. An ultra high impedance low level voltage follower is connected to the capacitor detector output through the cable, and shield means driven by the output of the ultra high impedance low level voltage follower are employed to shield the latter, the cable, and the probe, thereby minimizing the effective input capacitance of the ultra high impedance low level voltage follower. A high level voltage follower is connected to the output of the ultra high impedance low level voltage follower, and a floating power supply is connected to power the ultra high impedance low level voltage follower. The power supply is bootstrapped with the latter by the high level voltage follower through the connection of the common line of the floating power supply to the output of the high level voltage follower. The output of the high level voltage follower is connected to a peak-to-peak detector to derive an output voltage whose D.C. voltage is equal to the D.C. voltage of the surface under measurement.
Inventors
- 👤 R Vosteen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 20:14
CPC Classifications
G; G01; G01R; G01R5/00; G01R5/28
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
235 words
A wide band voltage follower circuit for deriving an output voltage whose amplitude is equal to the amplitude of the voltage of an electrostatically charged surface under measurement comprising: a probe having a capacitor detector arranged in spaced and noncontacting manner with the surface under measurement to detect the unknown surface voltage thereof, a cable connected to the output of the capacitor detector, a unity gain amplifier connected as an ultra high impedance low level voltage follower having an input and output, its input being connected directly to the capacitor detector output through the cable, first electrostatic shield means driven by the output of the ultra high impedance low level voltage follower, shielding the latter, the cable, and the probe to minimize the effective input capacitance of the ultra high impedance low level voltage follower, a high level voltage follower having an input and output, its input being connected to the output of the ultra high impedance low level voltage follower, a floating DC power supply having a DC supply output and a common line connected to power the ultra high impedance low level voltage follower, bootstrapped with the latter by the high level voltage follower through the connection of the common line of the floating power supply to the output of the high level voltage follower, and first means connected to the output of the high level voltage follower to derive the output voltage.
Claim 2
Dependent Claim
235 words
A wide band voltage follower circuit for deriving an output voltage whose amplitude is equal to the amplitude of the voltage of an electrostatically charged surface under measurement comprising: a probe having a capacitor detector arranged in spaced and noncontacting manner with the surface under measurement to detect the unknown surface voltage thereof, a cable connected to the output of the capacitor detector, a unity gain amplifier connected as an ultra high impedance low level voltage follower having an input and output, its input being connected directly to the capacitor detector output through the cable, first electrostatic shield means driven by the output of the ultra high impedance low level voltage follower, shielding the latter, the cable, and the probe to minimize the effective input capacitance of the ultra high impedance low level voltage follower, a high level voltage follower having an input and output, its input being connected to the output of the ultra high impedance low level voltage follower, a floating DC power supply having a DC supply output and a common line connected to power the ultra high impedance low level voltage follower, bootstrapped with the latter by the high level voltage follower through the connection of the common line of the floating power supply to the output of the high level voltage follower, and first means connected to the output of the high level voltage follower to derive the output voltage.
Claim 3
Dependent Claim
18 words
A wide band voltage follower as recited in claim 1 wherein the first means is a peak-to-peak detector.
Claim 4
Dependent Claim
65 words
A wide band voltage follower circuit as recited in claim 2 further comprising: a reference band region on the surface under measurement, biasing means connected to bias the peak-to-peak detector and reference band region to a reference voltage whose amplitude is equal to or greater than the maximum anticipated voltage of the derived output voltage that can be assumed for a given reference voltage polarity.
Claim 5
Dependent Claim
31 words
A wide band voltage follower as recited in claim 2 further comprising: electrometer means connected to the output of the peak-to-peak detector to provide a measurement of the unknown surface voltage.
Claim 6
Dependent Claim
56 words
A wide band amplifier as recited in claim 1 further comprising: an AC power source connected through transformer means to power the floating DC power supply, and second electrostatic shield means driven by the high level voltage follower output and shielding the transformer to minimize the capacitance of the AC power source to ground and line.
Claim 7
Dependent Claim
18 words
A wide band voltage follower circuit as recited in claim 5 wherein the detector is a peak-to-peak detector.
Claim 8
Dependent Claim
65 words
A wide band voltage follower circuit as recited in claim 6 further comprising: a reference band region on the surface under measurement, biasing means connected to bias the peak-to-peak detector and reference band region to a reference voltage whose amplitude is equal to or greater than the maximum anticipated voltage of the derived output voltage that can be assumed for a given reference voltage polarity.
Claim 9
Dependent Claim
31 words
A wide band voltage follower as recited in claim 6 further comprising: electrometer means connected to the output of the peak-to-peak detector to provide a measurement of the unknown surface voltage.
Claim 10
Dependent Claim
40 words
The wide band voltage follower as recited in claim 4 further comprising feedback means connected between the output and input of the ultra high impedance low-level voltage follower to provide high effective input resistance and stabilize the input operating point.
Claim 11
Dependent Claim
36 words
The wide band amplifier as recited in claim 5 further comprising protection means connected to the input of the ultra high impedance low-level voltage follower to prevent damage thereto in the event of excessive input voltage.
References Cited (Backward Citations)
US2881266A
Cited
US3436648A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-04-23 | 1976-10-23 | 1977-04-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-04-23 | 1980-10-23 | 1981-04-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-04-23 | 1984-10-23 | 1985-04-24 | $7700.00 | Window Closed / Lapsed |