US4284888A
Expired / Lapsed
US
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Pyroelectric detectors
Assignee: GEC-MARONI Ltd
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Filing: 1979-10-18
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Granted: 1981-08-18
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Expires: 1999-10-18
Abstract
Abstract An intruder detector consists of an element of pyroelectric material having three defined regions; two being active to infra-red radiation and one being relatively inactive to infra-red radiation. The inactive region and one of the active regions are connected together in parallel and the other active region is connected in series with these two. The arrangement has full cancellation of environment effects while being partially unbalanced for infra-red detection so that isolated areas of infra-red radiation (such as an intruder) can be detected at long and short ranges. The element is used with a concave mirror for increased zonal coverage. Each of the regions of pyroelectric material has a substantially constant thickness and all of the three regions have the same thickness.
Inventors
- 👤 David Appleby
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 14:10
CPC Classifications
H; H10; H10N; H10N15/00; H10N15/10; G; G08; G08B; G08B13/00; G08B13/18; G08B13/189; G08B13/19; G08B13/191; Y; Y10; Y10S; Y10S250/00; Y10S250/01
Claims Analysis
Total Claims: 35
Claim 1
Independent Claim
121 words
A pyroelectric detector comprising an element of pyroelectric material, said element having first and second regions, said first and second regions being connected in parallel with each other, said first region being active to infra-red radiation to produce a first output, said second region being relatively inactive to infra-red radiation so as to produce a null output, said element having a third region, said third region being connected in series with said first and second regions, said third region being oppositely polarized and active to infra-red radiation to produce a further output, wherein said first and further outputs are compared to each other, and are each compared to said null output, whereby to detect intrusion at both near and far ranges.
Claim 2
Dependent Claim
121 words
A pyroelectric detector comprising an element of pyroelectric material, said element having first and second regions, said first and second regions being connected in parallel with each other, said first region being active to infra-red radiation to produce a first output, said second region being relatively inactive to infra-red radiation so as to produce a null output, said element having a third region, said third region being connected in series with said first and second regions, said third region being oppositely polarized and active to infra-red radiation to produce a further output, wherein said first and further outputs are compared to each other, and are each compared to said null output, whereby to detect intrusion at both near and far ranges.
Claim 3
Dependent Claim
28 words
A pyroelectric detector as claimed in claim 1 wherein the area of said third region is substantially equal to the combined areas of said first and second regions.
Claim 4
Dependent Claim
29 words
A pyroelectric detector as claimed in claim 1 wherein said first and third regions of the element which are active to infra-red radiation are provided with infra-red absorbing coatings.
Claim 5
Dependent Claim
16 words
A pyroelectric detector as claimed in claim 3 wherein said coatings comprise platinum black applied electrochemically.
Claim 6
Dependent Claim
30 words
A pyroelectric detector as claimed in any one of claims 1, 2, 3 or 4 wherein each of said three regions of the pyroelectric material has a substantially constant thickness.
Claim 7
Dependent Claim
26 words
A pyroelectric detector as claimed in any one of claims 1, 2, 3 or 4 wherein all of said three regions have substantially the same thickness.
Claim 8
Dependent Claim
46 words
A pyroelectric detector as claimed in any one of claims 1, 2, 3 or 4 comprising an electrode, said electrode being non-transparent and highly reflective to infra-red radiation, said electrode being mounted on said second region of said element which is relatively inactive to infra-red radiation.
Claim 9
Dependent Claim
20 words
A pyroelectric detector as claimed in claim 7 wherein said non-transparent electrode comprises a layer of evaporated nichrome and gold.
Claim 10
Dependent Claim
25 words
A pyroelectric detector as claimed in any one of claims 1, 2, 3 or 4 wherein said pyroelectric material of said element comprises a ceramic.
Claim 11
Dependent Claim
16 words
A pyroelectric detector as claimed in claim 9 wherein said ceramic comprises lead zirconate iron niobate.
Claim 12
Dependent Claim
23 words
A pyroelectric detector as claimed in any one of claims 1, 2, 3 or 4 wherein said pyroelectric material comprises a single crystal.
Claim 13
Dependent Claim
15 words
A pyroelectric detector as claimed in claim 11 wherein said single crystal comprises lithium tantalate.
Claim 14
Dependent Claim
51 words
A pyroelectric detector as claimed in any one of claims 1, 2, 3 or 4 comprising a casing and thermal isolation means for providing thermal isolation between said casing and said element, said thermal isolation means being mounted on said casing and said element being mounted on said thermal isolation means.
Claim 15
Dependent Claim
38 words
A pyroelectric detector as claimed in any one of claims, 1, 2, 3 or 4 wherein said first and third regions of said element which are active to infra-red radiation have a ratio of areas of approximately 3:2.
Claim 16
Dependent Claim
26 words
A pyroelectric detector as claimed in any one of claims 1, 2, 3 or 4 comprising a concave mirror providing increased zonal coverage of said detector.
Claim 17
Dependent Claim
19 words
A pyroelectric detector as claimed in claim 5 wherein all of said three regions have substantially the same thickness.
Claim 18
Dependent Claim
39 words
A pyroelectric detector as claimed in claim 5 comprising an electrode, said electrode being non-transparent and highly reflective to infra-red radiation, said electrode being mounted on said second region of said element which is relatively inactive to infra-red radiation.
Claim 19
Dependent Claim
39 words
A pyroelectric detector as claimed in claim 6 comprising an electrode, said electrode being non-transparent and highly reflective to infra-red radiation, said electrode being mounted on said second region of said element which is relatively inactive to infra-red radiation.
Claim 20
Dependent Claim
18 words
A pyroelectric detector as claimed in claim 5 wherein said pyroelectric material of said element comprises a ceramic.
Claim 21
Dependent Claim
18 words
A pyroelectric detector as claimed in claim 6 wherein said pyroelectric material of said element comprises a ceramic.
Claim 22
Dependent Claim
18 words
A pyroelectric detector as claimed in claim 7 wherein said pyroelectric material of said element comprises a ceramic.
Claim 23
Dependent Claim
16 words
A pyroelectric detector as claimed in claim 5 wherein said pyroelectric material comprises a single crystal.
Claim 24
Dependent Claim
16 words
A pyroelectric detector as claimed in claim 6 wherein said pyroelectric material comprises a single crystal.
Claim 25
Dependent Claim
16 words
A pyroelectric detector as claimed in claim 7 wherein said pyroelectric material comprises a single crystal.
Claim 26
Dependent Claim
44 words
A pyroelectric detector as claimed in claim 5 comprising a casing and thermal isolation means for providing thermal isolation between said casing and said element, said thermal isolation means being mounted on said casing and said element being mounted on said thermal isolation means.
Claim 27
Dependent Claim
44 words
A pyroelectric detector as claimed in claim 6 comprising a casing and thermal isolation means for providing thermal isolation between said casing and said element, said thermal isolation means being mounted on said casing and said element being mounted on said thermal isolation means.
Claim 28
Dependent Claim
44 words
A pyroelectric detector as claimed in claim 7 comprising a casing and thermal isolation means for providing thermal isolation between said casing and said element, said thermal isolation means being mounted on said casing and said element being mounted on said thermal isolation means.
Claim 29
Dependent Claim
30 words
A pyroelectric detector as claimed in 5 wherein said first and third regions of said element which are active to infra-red radiation have a ratio of areas of approximately 3:2.
Claim 30
Dependent Claim
30 words
A pyroelectric detector as claimed in 6 wherein said first and third regions of said element which are active to infra-red radiation have a ratio of areas of approximately 3:2.
Claim 31
Dependent Claim
30 words
A pyroelectric detector as claimed in 7 wherein said first and third regions of said element which are active to infra-red radiation have a ratio of areas of approximately 3:2.
Claim 32
Dependent Claim
14 words
A pyroelectric detector as claimed in claim 15 wherein said concave mirror is multi-faceted.
Claim 33
Dependent Claim
19 words
A pyroelectric detector as claimed in claim 5 comprising a concave mirror providing increased zonal coverage of said detector.
Claim 34
Dependent Claim
19 words
A pyroelectric detector as claimed in claim 6 comprising a concave mirror providing increased zonal coverage of said detector.
Claim 35
Dependent Claim
19 words
A pyroelectric detector as claimed in claim 7 comprising a concave mirror providing increased zonal coverage of said detector.
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) | 1984-08-17 | 1985-02-16 | 1985-08-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-08-17 | 1989-02-16 | 1989-08-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-08-17 | 1993-02-16 | 1993-08-18 | $7700.00 | Window Closed / Lapsed |