US3874616A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrostatic field measuring device
Assignee: United States Department of the Army
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Filing: 1973-07-02
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Granted: 1975-04-01
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Expires: 1993-07-02
Abstract
Abstract This disclosure relates to electrostatic field strength and particularly to a device for detecting and indicating the strength of an electrostatic field in the vicinity of an aircraft. More particularly, this invention relates to a device for detecting and indicating the field strength in the vicinity of a helicopter or other device having rotating blades large enough physically to substantially alter the field strength pattern about the aircraft. In this device, the cyclically changing pattern of field strength caused by the rotation of the blades is sensed by a field probe to produce an alternating voltage that is applied to an amplifier and indicator that may be synchronized with the rotation of the blades, for noise component reduction.
Inventors
- 👤 Rudolf G Buser
- 👤 Helmuth M Kaunzinger
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 21:27
CPC Classifications
B; B64; B64D; B64D45/00; B64D45/02
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
155 words
An electrostatic field measuring device for a helicopter having a plurality of rotating blades projecting outwardly from a point above the fuselage of said helicopter comprising: a sensor electrode projecting downwardly and outwardly from said helicopter at a location on the lower surface of said fuselage substantially removed from the central axis of said helicopter; amplifying means including a lock-in amplifier having an input connected to said sensor electrode, for amplifying at least any alternating current component of the output of said sensor electrode; means associated with said rotor blades for gating said lock-in amplifier synchronously with said rotor blades to sample any signal on said sensor electrode repetitively to provide an alternating output at a reduced noise level; and indicating means connected to the output of said amplifying means for indicating the amplified level of any alternating current component from said sensor electrode, which is proportional to the electrostatic field adjacent to said device.
Claim 2
Dependent Claim
155 words
An electrostatic field measuring device for a helicopter having a plurality of rotating blades projecting outwardly from a point above the fuselage of said helicopter comprising: a sensor electrode projecting downwardly and outwardly from said helicopter at a location on the lower surface of said fuselage substantially removed from the central axis of said helicopter; amplifying means including a lock-in amplifier having an input connected to said sensor electrode, for amplifying at least any alternating current component of the output of said sensor electrode; means associated with said rotor blades for gating said lock-in amplifier synchronously with said rotor blades to sample any signal on said sensor electrode repetitively to provide an alternating output at a reduced noise level; and indicating means connected to the output of said amplifying means for indicating the amplified level of any alternating current component from said sensor electrode, which is proportional to the electrostatic field adjacent to said device.
Claim 3
Dependent Claim
60 words
An electrostatic field measuring device according to claim 1 having a rotor shaft projecting through a portion of the upper fuselage of said helicopter, said rotor shaft being coupled to drive said plurality of rotating blades; and means associated with said rotor shaft for developing a signal for gating said lock-in amplifier synchronously with the rotation of said rotor blades.
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) | 1978-03-31 | 1978-09-30 | 1979-04-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-31 | 1982-09-30 | 1983-04-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-31 | 1986-09-30 | 1987-04-01 | $7700.00 | Window Closed / Lapsed |