US3889251A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Photo electric ambiant light operated surveillance device
Assignee: Individual
•
Filing: 1973-08-01
•
Granted: 1975-06-10
•
Expires: 1993-08-01
Abstract
Abstract A surveillance device comprises two photo-sensitive devices arranged to receive light reflected respectively from an eye of the person under survey and from an area of skin adjacent to the eye, a differential amplifier for comparing signals generated by the photo-sensitive devices and means providing an alarm, e.g. an audible and/or visual alarm, when the signals generated by the devices are equal thus indicating that the person''s eye has closed.
Inventors
- 👤 Mitchel Litman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 15:07
CPC Classifications
A; A61; A61B; A61B3/00
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
57 words
A surveillance device comprising two photosensitive devices arranged to receive ambient light reflected respectively from an eye of the peRson under survey and from an area of skin adjacent to the eye, means for comparing signals generated by the photosensitive devices, and a device providing an alarm when the signals generated by the photo-sensitive devices are equal.
Claim 2
Dependent Claim
57 words
A surveillance device comprising two photosensitive devices arranged to receive ambient light reflected respectively from an eye of the peRson under survey and from an area of skin adjacent to the eye, means for comparing signals generated by the photosensitive devices, and a device providing an alarm when the signals generated by the photo-sensitive devices are equal.
Claim 3
Dependent Claim
40 words
A surveillance device according to claim 1, wherein the device is mounted on a frame adapted to be supported on the person''s head whereby the photo-sensitive devices are disposed adjacent to the eye but out of line of sight thereof.
Claim 4
Dependent Claim
17 words
A surveillance device according to claim 2, wherein the frame resembles that of a pair of spectacles.
Claim 5
Dependent Claim
20 words
A surveillance device according to claim 1, wherein the signals from the photo-sensitive devices are compared in a differential amplifier.
Claim 6
Dependent Claim
29 words
A surveillance device according to claim 4, wherein between the differential amplifier and the alarm device is disposed a delay circuit which prevents the alarm device from functioning prematurely.
Claim 7
Dependent Claim
18 words
A surveillance device according to claim 1, wherein two pairs of photo-sensitive devices of different sensitivities are provided.
References Cited (Backward Citations)
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US2726380A
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US2724109A
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US3089065A
Cited
US3340359A
Cited
US3379885A
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US3774134A
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-06-09 | 1978-12-09 | 1979-06-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-06-09 | 1982-12-09 | 1983-06-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-06-09 | 1986-12-09 | 1987-06-10 | $7700.00 | Window Closed / Lapsed |