US3667036A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrometer amplifier circuits
Assignee: Xerox Corp
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Filing: 1970-01-23
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Granted: 1972-05-30
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Expires: 1990-01-23
Abstract
Abstract Electrometer amplifier circuits for producing a voltage signal which is proportional to the electrostatic potential on an insulator. In a first embodiment, the electrometer amplifier circuit is controlled such that the output voltage is equal to the sensed electrostatic potential or multiples thereof. In a second embodiment, the circuit output nulls about the surface potential on the insulator.
Inventors
- 👤 Ned Jay Seachman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 22:15
CPC Classifications
G; G01; G01R; G01R5/00; G01R5/28
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
205 words
Apparatus for generating a modified electrical signal proportional to the electrostatic potential formed on an insulating surface comprising: a. means positioned adjacent to said insulating surface for producing an electrical signal proportional to said electrostatic potential, b. first circuit means connected to said producing means, said first circuit means having a high input impedance and a low gain, c. means connected to said first circuit means for providing a stable reference level for the output of said first circuit means, d. second circuit means connected to the output of said reference level providing means, said second circuit means providing a controlled voltage gain and impedance transformation between the reference level means and subsequent apparatus, e. a peak detector connected to the output of said second circuit means, f. means for generating a signal which is proportional to the difference between the signals applied to its input terminals, g. means for connecting the output of said peak detector to one input terminal of said generating meaNs, h. means for amplifying the output of said generating means, the output of said amplifying means being said modified electrical signal, and i. means for coupling the output of said amplifying means to the other input of said generating means.
Claim 2
Dependent Claim
205 words
Apparatus for generating a modified electrical signal proportional to the electrostatic potential formed on an insulating surface comprising: a. means positioned adjacent to said insulating surface for producing an electrical signal proportional to said electrostatic potential, b. first circuit means connected to said producing means, said first circuit means having a high input impedance and a low gain, c. means connected to said first circuit means for providing a stable reference level for the output of said first circuit means, d. second circuit means connected to the output of said reference level providing means, said second circuit means providing a controlled voltage gain and impedance transformation between the reference level means and subsequent apparatus, e. a peak detector connected to the output of said second circuit means, f. means for generating a signal which is proportional to the difference between the signals applied to its input terminals, g. means for connecting the output of said peak detector to one input terminal of said generating meaNs, h. means for amplifying the output of said generating means, the output of said amplifying means being said modified electrical signal, and i. means for coupling the output of said amplifying means to the other input of said generating means.
Claim 3
Dependent Claim
15 words
The apparatus as defined in claim 1 wherein said generating means is a differential amplifier.
Claim 4
Dependent Claim
34 words
The apparatus as defined in claim 2 wherein said coupling means comprises a variable potentiometer having an adjustable tap, the tap of said potentiometer being connected to the other input of said differential amplifier.
Claim 5
Dependent Claim
24 words
The apparatus as defined in claim 3 wherein the magnitude of said modified electrical signal is determined by the position of said adjustable tap.
Claim 6
Dependent Claim
16 words
The apparatus as defined in claim 4 wherein said modified electrical signal equals said electrostatic potential.
Claim 7
Dependent Claim
21 words
The apparatus as defined in claim 4 wherein said modified electrical signal is a fixed multiple of said electrostatic potential .
Claim 8
Dependent Claim
14 words
The apparatus as defined in claim 1 wherein said insulating surface comprises a photoconductor.
Claim 9
Dependent Claim
166 words
Apparatus for generating an electrical signal which is proportional to the electrostatic potential formed on an insulating surface comprising: a. a probe assembly positioned adjacent said insulating surface, said probe assembly comprising a probe electrode and a guard electrode, the probe electrode producing an electrical signal proportional to said electrostatic potential, b. means for producing a signal which is proportional to the difference in magnitude between signals applied to its input terminals, c. first means for coupling the electrical signal appearing at the output of said probe electrode to one input of said producing means, d. amplifier means connected to the output of said producing means for amplifying the output thereof, the output of said amplifier means being proportional to the electrostatic potential on said insulating surface, and e. second means for coupling the output of said amplifier means to said guard electrode and to the other input terminal of said producing means, whereby the output of said amplifier means is nulled about said electrostatic potential.
Claim 10
Dependent Claim
166 words
Apparatus for generating an electrical signal which is proportional to the electrostatic potential formed on an insulating surface comprising: a. a probe assembly positioned adjacent said insulating surface, said probe assembly comprising a probe electrode and a guard electrode, the probe electrode producing an electrical signal proportional to said electrostatic potential, b. means for producing a signal which is proportional to the difference in magnitude between signals applied to its input terminals, c. first means for coupling the electrical signal appearing at the output of said probe electrode to one input of said producing means, d. amplifier means connected to the output of said producing means for amplifying the output thereof, the output of said amplifier means being proportional to the electrostatic potential on said insulating surface, and e. second means for coupling the output of said amplifier means to said guard electrode and to the other input terminal of said producing means, whereby the output of said amplifier means is nulled about said electrostatic potential.
Claim 11
Dependent Claim
43 words
The apparatus as defined in claim 8 further including a peak detecting means connected to the output of said amplifier means, the output of said peak detecting means being a voltage proportional to the peak value of the output of said amplifying means.
Claim 12
Dependent Claim
24 words
The apparatus as defined in claim 9 wherein said first coupling means comprises an amplifier having a high input impedance and substantially unity gain.
Claim 13
Dependent Claim
15 words
The apparatus as defined in claim 10 wherein said producing means comprises a differential amplifier.
Claim 14
Dependent Claim
13 words
The apparatus defined in claim 8 wherein said insulating surface comprises a photoconductor.
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) | 1975-05-30 | 1975-11-29 | 1976-05-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-30 | 1979-11-29 | 1980-05-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-30 | 1983-11-29 | 1984-05-30 | $7700.00 | Window Closed / Lapsed |