US5451931A
Expired / Lapsed
US
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Optical smoke detector
Assignee: Cerberus AG
•
Filing: 1993-09-14
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Granted: 1995-09-19
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Expires: 2013-09-14
Abstract
Abstract Optical smoke detectors such as extinction smoke detectors and scattered-light smoke detectors include a radiation source, a radiation detector or receiver, and a measurement volume which is in communication with ambient atmosphere and which is traversed by a light path from the radiation source to the radiation receiver. For compactness and simplicity, such an optical smoke detector is provided with a planar-optical element in the optical path. Suitable as planar-optical elements are diffractive elements, e.g., holographic-optical elements (HOE), and micro-Fresnel elements (MFE), e.g., micro-Fresnel reflectors (MFR).
Inventors
- 👤 Kurt Muller
- 👤 Peter Ryser
- 👤 Dieter Wieser
- 👤 Rino E. Kunz
- 👤 Markus Rossi
- 👤 Michael T. Gale
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 06:43
CPC Classifications
G; G08; G08B; G08B17/00; G08B17/10; G08B17/103; G08B17/107; G08B17/11; G08B17/113
Claims Analysis
Total Claims: 31
Claim 1
Independent Claim
123 words
An optical smoke detector comprising at least one radiation source (1) and at least one radiation receiver (2) in optical receiving relationship with the radiation source (1) via an optical path, wherein: the optical path traverses a measurement volume (8) accessible to ambient atmosphere; the radiation receiver (2) is sensitive to radiation changes caused by smoke particles (12) in the measurement volume (8), for producing a signal to an electronic evaluation circuit as a function of radiation incident on the radiation receiver (2); and at least one planar-optical element (5) is disposed in the optical smoke detector, for optical microstructure of the planar-optical element to interact with light traveling in the optical path from the radiation source (1) to the radiation receiver (2).
Claim 2
Dependent Claim
123 words
An optical smoke detector comprising at least one radiation source (1) and at least one radiation receiver (2) in optical receiving relationship with the radiation source (1) via an optical path, wherein: the optical path traverses a measurement volume (8) accessible to ambient atmosphere; the radiation receiver (2) is sensitive to radiation changes caused by smoke particles (12) in the measurement volume (8), for producing a signal to an electronic evaluation circuit as a function of radiation incident on the radiation receiver (2); and at least one planar-optical element (5) is disposed in the optical smoke detector, for optical microstructure of the planar-optical element to interact with light traveling in the optical path from the radiation source (1) to the radiation receiver (2).
Claim 3
Dependent Claim
40 words
The optical smoke detector of claim 1, wherein the radiation receiver (2) is sensitive to radiation scattered by the smoke particles (12), and further comprising a radiation trap (3) disposed for minimizing parasitic radiation from reaching the radiation receiver (2).
Claim 4
Dependent Claim
18 words
The optical smoke detector of claim 2, wherein the planar-optical element (5) is a holographic optical element (HOE).
Claim 5
Dependent Claim
17 words
The optical smoke detector of claim 2, wherein the planar-optical element (5) is a micro-Fresnel reflector (MFR).
Claim 6
Dependent Claim
50 words
The optical smoke detector of claim 4, wherein the micro-Fresnel reflector (MFR) comprises a plurality of microsurfaces, disposed such that, for a predetermined wavelength, optical paths between the radiation source (1) and the radiation receiver (2) via different microsurfaces have lengths which differ by an integral multiple of the wavelength.
Claim 7
Dependent Claim
18 words
The optical smoke detector of claim 5, wherein the wavelength is at least approximately equal to 880 nm.
Claim 8
Dependent Claim
26 words
The optical smoke detector of claim 2, wherein the planar-optical element (5) is a reflective element having a microsurface structure on a side of light incidence.
Claim 9
Dependent Claim
30 words
The optical smoke detector of claim 2, wherein the planar-optical element (5) is a reflective element having a microsurface structure on a side opposite to a side of light incidence.
Claim 10
Dependent Claim
24 words
The optical smoke detector of claim 2, wherein the optical radiation source (1) and the optical receiver (2) are disposed on a printed-circuit board.
Claim 11
Dependent Claim
19 words
The optical smoke detector of claim 9, wherein the planar-optical element (5) is exposed to the radiation source (1).
Claim 12
Dependent Claim
19 words
The optical smoke detector of claim 9, wherein the planar-optical element (5) is exposed to the radiation receiver (2).
Claim 13
Dependent Claim
35 words
The optical smoke detector of claim 9, comprising at least two planar-optical elements (5), one planar-optical element (5) being exposed to the radiation source (1) and another planar-optical element being exposed to the radiation receiver.
Claim 14
Dependent Claim
28 words
The optical smoke detector of claim 2, comprising an auxiliary mirror element (13) disposed for deflecting light not scattered from smoke particles (12) into the radiation trap (3).
Claim 15
Dependent Claim
18 words
The optical smoke detector of claim 13, wherein the auxiliary mirror element (13) has a flat mirror surface.
Claim 16
Dependent Claim
18 words
The optical smoke detector of claim 13, wherein the auxiliary mirror element (13) has a curved mirror surface.
Claim 17
Dependent Claim
16 words
The optical smoke detector of claim 9, wherein the radiation source (1) is an infrared-emitting diode.
Claim 18
Dependent Claim
16 words
The optical smoke detector of claim 9, wherein the radiation source (1) is a laser diode.
Claim 19
Dependent Claim
19 words
The optical smoke detector of claim 2, further comprising a polarization filter (15) exposed to the radiation receiver (2).
Claim 20
Dependent Claim
40 words
The optical smoke detector of claim 18, wherein the polarization filter (15) has a plane of polarization which is perpendicular to a plane of scattering defined by the optical path from the radiation source (1) to the radiation receiver (2).
Claim 21
Dependent Claim
23 words
The optical smoke detector of claim 2, comprising at least two different-color radiation sources (1) and at least two spaced-apart radiation receivers (2).
Claim 22
Dependent Claim
74 words
The optical smoke detector of claim 2, comprising at least two spaced-apart radiation receivers (21, 22), wherein the planar-optical element (5) comprises two microsurface regions (A, B) having different foci and being disposed for deflecting scattered light from the measurement volume (8) to the two radiation receivers (21, 22), further comprising two polarization filters (14, 15) having different planes of polarization and each (14, 15) being disposed at a respective radiation receiver (22, 21).
Claim 23
Dependent Claim
21 words
The optical smoke detector of claim 21, wherein the polarization filters (14, 15) have planes of polarization which are mutually perpendicular.
Claim 24
Dependent Claim
131 words
The optical smoke detector of claim 2, comprising at least two different-color radiation sources (1) and at least five spaced-apart radiation receivers (21, 22, 23, 24, 25), wherein the planar-optical element (5) comprises two microsurface regions (A, B) having different foci and a superposed structure, disposed for deflecting scattered light from the measurement volume (8) to the five radiation receivers (21, 22, 23, 24, 25), two pairs (21 and 22, 24 and 25) of the five radiation receivers (21, 22, 23, 24, 25) being provided with polarization filters (14, 15) such that the joint planes of polarization of polarization filters (14) of one pair (21 and 22) of radiation receivers are different from the joint planes of polarization of polarization filters (15) of another pair (24 and 25) of radiation receivers.
Claim 25
Dependent Claim
14 words
The optical smoke detector of claim 23, wherein the superposed structure is a grating.
Claim 26
Dependent Claim
49 words
The optical smoke detector of claim 23, wherein the joint planes of polarization of polarization filters (14) of the one pair (21 and 22) of radiation receivers are perpendicular to the joint planes of polarization of polarization filters (15) of the other pair (24 and 25) of radiation receivers.
Claim 27
Dependent Claim
19 words
The optical smoke detector of claim 2, wherein the planar-optical element (5) is laminated to the radiation trap (3).
Claim 28
Dependent Claim
18 words
The optical smoke detector of claim 2, wherein the planar-optical element is embossed on the radiation trap (3).
Claim 29
Dependent Claim
26 words
The optical smoke detector of claim 2, further comprising a mirror (27) in the optical path from the radiation source (1) to the radiation receiver (2).
Claim 30
Dependent Claim
19 words
The optical smoke detector of claim 28, wherein the mirror (27) is a shallow depression in a plastic housing.
Claim 31
Dependent Claim
23 words
The optical smoke detector of claim 1, wherein the radiation receiver (2) is sensitive to extinction of radiation in the measurement volume (8).
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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) | 1998-09-18 | 1999-03-20 | 1999-09-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-09-18 | 2003-03-20 | 2003-09-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-09-18 | 2007-03-20 | 2007-09-19 | $7700.00 | Window Closed / Lapsed |