US3766539A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic personnel intrusion alarm
Assignee: United States Department of the Army
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Filing: 1972-05-01
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Granted: 1973-10-16
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Expires: 1992-05-01
Abstract
Abstract The invention is concerned with infrared viewing systems, particularly those operating in the spectral wavelength regions between 3 to 5 and 8 to 14 microns. An alarm is provided for these systems to draw particular attention to subtle or drastic changes in the scene being viewed, thereby reducing operator fatigue or relieving the operator to perform other tasks simultaneously.
Inventors
- 👤 B Bradshaw
- 👤 H Graves
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 14:22
CPC Classifications
G; G08; G08B; G08B13/00; G08B13/18; G08B13/189; G08B13/19; Y; Y10; Y10S; Y10S250/00; Y10S250/01
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
96 words
In combination with a far infrared viewer wherein an infrared image is scanned by a detector diode to produce a video output signal: a bandpass AGC amplifier having its input coupled to said viewer to monitor sAid video signal; a highpass amplifier with a low frequency cutoff at approximately two kilocycles serially coupled to said bandpass amplifier; a signal detector with a time constant less than three seconds serially coupled to said highpass amplifier; and an alarm means coupled to said detector to emit an alarm signal when significant changes occur in the video signal amplitude.
Claim 2
Dependent Claim
96 words
In combination with a far infrared viewer wherein an infrared image is scanned by a detector diode to produce a video output signal: a bandpass AGC amplifier having its input coupled to said viewer to monitor sAid video signal; a highpass amplifier with a low frequency cutoff at approximately two kilocycles serially coupled to said bandpass amplifier; a signal detector with a time constant less than three seconds serially coupled to said highpass amplifier; and an alarm means coupled to said detector to emit an alarm signal when significant changes occur in the video signal amplitude.
Claim 3
Dependent Claim
24 words
The combination according to claim 1 wherein said AGC amplifier includes a feedback circuit for automatic gain control with a 3 second time constant.
Claim 4
Dependent Claim
17 words
The combination according to claim 1 wherein said signal detector has a time constant of 0.15 second.
Claim 5
Dependent Claim
20 words
The combination according to claim 1 wherein said AGC and high-pass amplifiers have a band pass of approximately 40 kilohertz.
Claim 6
Dependent Claim
15 words
The combination according to claim 1 wherein said alarm means emits an audible alarm signal.
Claim 7
Dependent Claim
14 words
The combination according to claim 1 wherein said alarm means emits a visible signal.
References Cited (Backward Citations)
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US3703718B1
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-10-15 | 1977-04-16 | 1977-10-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-15 | 1981-04-16 | 1981-10-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-15 | 1985-04-16 | 1985-10-16 | $7700.00 | Window Closed / Lapsed |