US3839640A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Differential pyroelectric sensor
Assignee: Individual
•
Filing: 1973-06-20
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Granted: 1974-10-01
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Expires: 1993-06-20
Abstract
Abstract A low cost mass produced intrusion detection device which responds to a temperature difference between ambient temperature and the body temperature of an intruder who is moving past the sensor. The combination of body temperature and movement will unbalance the differential sensor to thereby trigger an alarm. This sensor utilizes a pyroelectric plastic film as the active element. It is not affected by ambient heat. Only a moving person or object can be detected to sound an alarm.
Inventors
- 👤 J Rossin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 06:32
CPC Classifications
G; G01; G01J; G01J5/00; G01J5/10; G01J5/34; G08; G08B; G08B13/00; G08B13/18; G08B13/189; G08B13/19; G08B13/191; H; H10; H10N; H10N15/00; H10N15/10; Y; Y10; Y10S; Y10S250/00; Y10S250/01
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
100 words
A pyroelectric differential passive infrared sensor comprising: a. a pyroelectric plastic film having front and rear sides, b. two front conductive stripes applied to the front side of said film, c. a rear conductive stripe applied to the rear side of said film overlapping in part said front conductive stripes defining thereby two heat sensitive capacitors in series with said two front conductive stripes serving as output leads, d. said two heat sensitive capacitors being connected to said front conductive stripes in parallel electrically but in series physically and with said electrode on the rear of said film floating electrically.
Claim 2
Dependent Claim
100 words
A pyroelectric differential passive infrared sensor comprising: a. a pyroelectric plastic film having front and rear sides, b. two front conductive stripes applied to the front side of said film, c. a rear conductive stripe applied to the rear side of said film overlapping in part said front conductive stripes defining thereby two heat sensitive capacitors in series with said two front conductive stripes serving as output leads, d. said two heat sensitive capacitors being connected to said front conductive stripes in parallel electrically but in series physically and with said electrode on the rear of said film floating electrically.
Claim 3
Dependent Claim
21 words
The detector of claim 1 comprising in addition a high value resistor joining said first conductive stripes at their output ends.
Claim 4
Dependent Claim
13 words
The detector of claim 1 wherein said pyroelectric plastic film is polyvinylidene fluoride.
Claim 5
Dependent Claim
59 words
The detector of claim 1 comprising in addition: a. a field effect transistor having gate, source, and drain leads; b. circuit means connecting one of said first conductive stripes to the gate lead of said field effect transistor; and c. circuit means connecting the other of said first conductive stripes to the system ground for said field effect transistor.
Claim 6
Dependent Claim
42 words
The detector of claim 4 comprising in addition a diode in the drain lead of said field effect transistor whereby the diode causes the voltage on the source lead to swing only towards the positive supply in event of a line transient.
Claim 7
Dependent Claim
39 words
The detector of claim 1 comprising in addition: a. radiation gathering means disposed effective to direct background radiation to said capacitors substantially equally and to direct radiation from a moving intruder to either but not both of said capacitors.
Claim 8
Dependent Claim
14 words
The apparatus of claim 6 wherein said radiation gathering means is a concave mirror.
Claim 9
Dependent Claim
19 words
The apparatus of claim 6 comprising in addition a sealed housing containing said detector and said radiation gathering means.
Claim 10
Dependent Claim
26 words
The apparatus of claim 6 wherein said sealed housing is provided with a window of polyethylene film through which radiation impinges upon said radiation gathering means.
Claim 11
Dependent Claim
72 words
The detector of claim 1 comprising in addition: a. a field effect transistor, b. a ground wire having one end connected to one of said first conductive stripes and the other end wrapped around said field effect transistor, c. an insulating spacer block disposed between said film and said field effect transistor, and d. circuit means connecting the other of said first conductive stripes to the gate of said field effect transistor.
Claim 12
Independent Claim
49 words
A method for the fabrication of infrared detectors comprising: a. painting conductive stripes on two sides of pyroelectric film to define at least two capacitors, b. applying a polarizing voltage to said capacitors in parallel, and c. connecting output leads to like polarity electrodes of said capacitors in series.
Claim 13
Independent Claim
49 words
A method for the fabrication of infrared detectors comprising: a. painting conductive stripes on two sides of pyroelectric film to define at least two capacitors, b. applying a polarizing voltage to said capacitors in parallel, and c. connecting output leads to like polarity electrodes of said capacitors in series.
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) | 1977-09-30 | 1978-04-01 | 1978-10-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-09-30 | 1982-04-01 | 1982-10-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-09-30 | 1986-04-01 | 1986-10-01 | $7700.00 | Window Closed / Lapsed |