CN102129755A - Photoelectric smoke detector based on forward scattering in small angle - Google Patents
Photoelectric smoke detector based on forward scattering in small angle Download PDFInfo
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- CN102129755A CN102129755A CN 201110001456 CN201110001456A CN102129755A CN 102129755 A CN102129755 A CN 102129755A CN 201110001456 CN201110001456 CN 201110001456 CN 201110001456 A CN201110001456 A CN 201110001456A CN 102129755 A CN102129755 A CN 102129755A
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Abstract
The invention discloses a photoelectric smoke detector based on forward scattering in a small angle. The detector comprises a detection chamber provided with a light source, an incident lens, a receiving lens system and a detector which have the same optical axis in sequence; a baffle board is arranged between the receiving lens system and the detector; the incident lens focuses the incident light of the light source on particles in the center of the detection chamber; and the receiving lens system transmits the forward scattering light in a small angle of the particles in the center of the detection chamber to the detector. The photoelectric smoke detector lowers the requirements on the sensitivity of the detector, increases the response speed for smoke particles, decreases the false alarm rate of the detector and reduces the error of obtaining the scattering intensity distribution.
Description
Technical field
The present invention relates to the fire detection technology field, be specially a kind of optical detector of fire smoke based on the forward direction small angle scattering.
Background technology
Detection is the important means that prevents that fire from taking place, and is that current fire detection alarm system adopts the most conventional detector based on the optical detector of fire smoke of light scattering principle.The optical detector of fire smoke of prior art usually adopts in forward direction or back the scattered light intensity signal that receives a certain specific wavelength (being generally near infrared light) to a certain specific scattering angle to realize the perception of smoke particle, as patent CN101147053, CN1198237 etc.This class detector mainly exists interference particles such as can't effectively discerning dust to cause being easy to generate the defective of wrong report.The existence of wrong report has seriously influenced the use of optical detector of fire smoke, National Fire Protection Association (National Fire Protection Association) is pointed out in portions in 2004 " wrong report and accidental activation: U.S.'s smoke detector and other detections/panalarm investigation " by name (" False Alarms and Unwanted Activiations " From:U.S. Experience with Smoke Alarms and other Fire Detection/Alarm Equipment) research report, in order to reduce the interference of detector wrong report to life, people remove the battery in the detector usually, and it is 8 times of other similar electrical equipment that the battery of smoke detector removes rate.The existence of wrong report often makes optical detector of fire smoke can't bring into play the warning function of its application when natural fire takes place, thereby causes heavy losses to society.
As the improvement of prior art, some detectors have proposed to use the light source of two different wave lengths, utilize the difference of the signal of the different wave length that the particle scattering obtains to discern dust and smoke signal, as patent CN101135630A etc.This technology is the also inevitable response that has suppressed smoke particle when utilizing the method after the dual wavelength scattered signal subtracts each other to suppress response to the large scale dust granule.
Improved another kind of scheme as prior art, in patents such as CN 1234003C, CN101036173A, propose to adopt forward direction and back to receiver is set respectively, utilize other combinatorial operation of the ratio of forward direction and rear orientation light or certain to discern black smoke (white cigarette) and dust.This technology relates at the back azimuth degree and surveys scattered light, and smog, the especially back scattering of black smoke particle are very faint, therefore to the requirement of detector sensitivity than higher.
Summary of the invention
The object of the present invention is to provide a kind of optical detector of fire smoke based on the forward direction small angle scattering, utilize the strongest forward direction small angle scattering of scattered signal to realize the high sensitivity of smoke particle is responded, reduced requirement, and improved the identification of large scales such as dust being disturbed particle effectively device sensitivity.
In order to achieve the above object, the technical solution adopted in the present invention is:
A kind of optical detector of fire smoke based on the forward direction small angle scattering, it is characterized in that: include the detection chamber that constitutes the darkroom environment, described detection chamber center one side is disposed with light source, the incident lens, the focus of described incident lens is positioned at surveys the chamber center, the incident lens focus on the incident light of light source on the particle swarm of detection chamber center, described detection chamber center opposite side is disposed with receiving lens system, detector, described light source, the incident lens, receiving lens system, the test surface common optical axis of detector, be provided with the dividing plate of the test surface center that is positioned at detector between receiving lens system and the detector, described receiving lens system will be surveyed the forward direction small angle scattering light transmission of chamber center particle swarm to detector, and described detector is connected with the signal processing unit of outside.
Described a kind of optical detector of fire smoke based on the forward direction small angle scattering, it is characterized in that: described receiving lens system comprises first receiver lens that common optical axis is provided with, second receiver lens, described first, second receiver lens is achromatism plano-convex thin lens, wherein the focus of first receiver lens is positioned at and surveys the chamber center, described first receiver lens receives the forward direction small angle scattering light of surveying chamber center particle swarm and also images in the picture plane, described second receiver lens make be positioned at described as the scattered light on the plane with perpendicular on the parallel test surface that is incident to detector of the angle of detector test surface.
Described a kind of optical detector of fire smoke based on the forward direction small angle scattering, it is characterized in that: described detector is a linear array detector, it perhaps is the detector array that a plurality of photodiodes constitute, second receiver lens makes and is positioned at as the scattered light on the plane with perpendicular on the parallel test surface that is incident to detector of the angle of detector test surface in the described receiving lens system, make the not homophase unit of the corresponding linear array detector of scattered light of different scattering angle simultaneously, or the different detecting locations of the detector array of a plurality of photodiode formation.
The grain optical scattering feature is the embodiment of some character of particle, mainly comprises particle grain size and refractive index.According to the disclosed content of paper " on-line measurement of test fire smoke particle optical property " (On-line determination of optical properties of particles produced by test fires) on the 266th page to the 273rd page of " the full periodical of fire " (Fire Safety Journal) 2006 the 41st volume, black smoke particle that normal heptane and polyurethane burning produce and ash (in vain) smoke particle that timber glows and cotton cord glows to be produced, difference on size distribution is also not obvious, mainly be distributed in 10 nanometers to 1 micrometer range, geometric mean diameter is about 200 nanometers, and geometric standard deviation is usually near 2; And the black smoke particle mainly causes by refractive index is different with the difference of ash (in vain) smoke particle on light scattering intensity: black smoke particle refractive index imaginary part is bigger usually, therefore produces stronger light absorption, causes light scattering intensity less than normal.Dust granule is that abrasion or the non-thermal decomposition by natural materials in the environment or biosome produced, and compares with smoke particle, and the size of dust granule is generally very big, mainly is distributed in 1 micron within the 100 micron grain size scopes.
Smog and dust granule are following feature in the light scattering intensity of visible near-infrared wave band in the distribution of the little scattering angle of forward direction: scattering angle is spent in the process that begins to increase by 0, and the light scattering intensity of smog and dust granule all from large to small; But there is significant difference in scattering strength in both with the scattering angle increase on the decline scope, compare smoke particle, dust granule can drop to the difference of several magnitude in preceding 20 degree range of scatter angles, smoke particle then descends usually and is no more than an order of magnitude.The present invention is provided with detection system by near the little range of scatter angles internal fixation forward direction zero degree scattering angle, can obtain the light distribution of forward direction low-angle by this detection system, utilizes this light distribution information can effectively differentiate smoke particle and dust granule.
The forward direction small angle scattering that the present invention utilizes the particle scattared energy to concentrate has the most reduced the requirement to detector sensitivity, has improved the response of smoke particle.Utilize the distributed intelligence of forward direction light intensity can realize the identification of smoke particle and dust granule simply and effectively, reduced the wrong report of detector.The use of receiving lens system has avoided the incident angle difference to cause the inconsistent problem of explorer response, has reduced to obtain the error that scattered light intensity distributes.
Description of drawings
Fig. 1 is the optical detector of fire smoke floor map based on the forward direction small angle scattering of the present invention.
Fig. 2 is that lens combination of the present invention is formed synoptic diagram.
Fig. 3 is typical smoke particle and the relative Distribution calculation of dust granule forward direction small angle scattering light intensity figure as a result under the 532nm wavelength.
Embodiment
As shown in Figure 1 and Figure 2.The present invention includes light radiating portion, light receiving part and signal processing system.The light radiating portion comprises light source 1 and incident lens 2, and the light beam of light source 1 outgoing is incident to the scattering center 3 of surveying chamber 8 centers after incident lens 2 focus on, and with the particle swarm 4 that enters scattering center 3 the light scattering effect takes place.Light receiving part comprises receiving lens system 5, dividing plate 6, forward direction small angle scattering light transmission is to detector 7 test surfaces in the scattering reference plane that detector 7, receiving lens system 5 send scattering center, and the scattering reference plane can be the arbitrary plane through incident beam.Dividing plate 6 is on the emission light path between receiving lens system 5 and the detector 7, be used to block incident ray through behind the smoke particle, avoid shining directly into detector 7, detector 7 is linear array detector or the detector array be made up of a plurality of photodiodes, is used to measure the one-dimensional scattering light intensity distributions after the imaging.Receiving lens system 5 is made of two groups of achromatism plano-convex thin lenss, the first receiver lens 5-1 collects scattering center forward direction small angle scattering light and images in the picture plane, the second receiver lens 5-2 makes and is positioned at as the scattered light on the plane to incide on detector 7 test surfaces perpendicular to the angle of detector 7 test surfaces is parallel, makes corresponding different detector 7 detecting locations of the scattered light of different scattering angle or the not homophase unit of linear array detector simultaneously.
Optical detector of fire smoke based on the forward direction small angle scattering provided by the present invention is that the scattered light that the application detection system receives is discerned smoke particle and dust granule with the scattering angle distributed intelligence.
Surveying chamber 8 is a cylindrical darkroom, and by can stopping entering of surrounding environment light, but smoke particle can successfully enter, and for example can adopt one group of " V " shape thin slice to constitute the sidewall of cylindrical chamber.In a side of surveying chamber 8 light source 1 is installed, light source 1 can adopt the laser diode or the light emitting diode of visible near-infrared wave band (between the 400nm-900nm), preferably adopts laser diode.Along light source 1 outgoing direction of light incident lens 2 are installed successively, receiving lens system 5, dividing plate 6 and detector 7.Incident lens 2 focus on detection chamber 8 centers with the light of light source 1 outgoing, with the particle swarm 4 generation scatterings in the scattering center 3.The forward scattering light that receiving lens system 5 collection scattering centers are sent also is mapped to detector 7.Dividing plate 6 is positioned on the input path of detector 7 front ends, is used to block the incident light through smog, avoid the direct irradiation detector, so detector zero degree scattering angle position will not receive any light intensity.
Receiving lens system 5 is made of two groups of lens, scattering center 3 is positioned at the focus place of the first receiver lens 5-1, the first receiver lens diameter is chosen for the scattered light of (scatteringangle is less than 20 degree among Fig. 3) in the 20 degree scopes of can collecting, the second receiver lens 5-2 will be positioned at the first receiver lens 5-1 and be mapped on the detector 7 as the scattered beam on plane, and make scattered light to incide on detector 7 test surfaces perpendicular to the angle of detector 7 test surfaces is parallel, make the corresponding different detector detecting location of scattered light of different scattering angle or the not homophase unit of linear array detector simultaneously.
As shown in Figure 3.Fig. 3 has provided the calculating chart of smoke particle and dust granule forward scattering light intensity distributions when lambda1-wavelength is 532nm.Confirmablely be, the Michaelis theory is applicable to calculates the endocorpuscular light scattering of range of size that visible near-infrared wave band conforms with conventional smog and dust, and lognormal distribution can be used for describing and conforms with the conventional smog and the size distribution of dust granule.For smoke particle, choosing geometric mean diameter is 200nm, and geometric standard deviation is 1.8, and particle size distribution range is between 10 nanometers-1 micron, and refractive index is respectively 1.53+0.56i (black smoke) and the white cigarette of 1.53+0.01i(); For dust granule, selecting geometric mean diameter is 5 microns, and geometric standard deviation is 1.8, and particle size distribution range is between 1 micron-100 microns, and refractive index is 1.53+0.01i.We find to have marked difference on smoke particle and the dust granule forward scattering light distribution characteristics by result of calculation.
Claims (3)
1. optical detector of fire smoke based on the forward direction small angle scattering, it is characterized in that: include the detection chamber that constitutes the darkroom environment, described detection chamber center one side is disposed with light source, the incident lens, the focus of described incident lens is positioned at surveys the chamber center, the incident lens focus on the incident light of light source on the particle swarm of detection chamber center, described detection chamber center opposite side is disposed with receiving lens system, detector, described light source, the incident lens, receiving lens system, the test surface common optical axis of detector, be provided with the dividing plate of the test surface center that is positioned at detector between receiving lens system and the detector, described receiving lens system will be surveyed the forward direction small angle scattering light transmission of chamber center particle swarm to detector, and described detector is connected with the signal processing unit of outside.
2. a kind of optical detector of fire smoke according to claim 1 based on the forward direction small angle scattering, it is characterized in that: described receiving lens system comprises first receiver lens that common optical axis is provided with, second receiver lens, described first, second receiver lens is achromatism plano-convex thin lens, wherein the focus of first receiver lens is positioned at and surveys the chamber center, described first receiver lens receives the forward direction small angle scattering light of surveying chamber center particle swarm and also images in the picture plane, described second receiver lens make be positioned at described as the scattered light on the plane with perpendicular on the parallel test surface that is incident to detector of the angle of detector test surface.
3. a kind of optical detector of fire smoke according to claim 1 based on the forward direction small angle scattering, it is characterized in that: described detector is a linear array detector, it perhaps is the detector array that a plurality of photodiodes constitute, second receiver lens makes and is positioned at as the scattered light on the plane with perpendicular on the parallel test surface that is incident to detector of the angle of detector test surface in the described receiving lens system, make the not homophase unit of the corresponding linear array detector of scattered light of different scattering angle simultaneously, or the different detecting locations of the detector array of a plurality of photodiode formation.
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| Application Number | Priority Date | Filing Date | Title |
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| CN2011100014566A CN102129755B (en) | 2011-01-06 | 2011-01-06 | Photoelectric smoke detector based on forward scattering in small angle |
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| CN2011100014566A CN102129755B (en) | 2011-01-06 | 2011-01-06 | Photoelectric smoke detector based on forward scattering in small angle |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103366495A (en) * | 2013-07-11 | 2013-10-23 | 合肥工业大学 | Air-breathing high-sensitivity smoke particle detector and application thereof |
| CN103575658A (en) * | 2012-08-10 | 2014-02-12 | 能美防灾株式会社 | Photoelectric separation type detector |
| CN107516397A (en) * | 2017-09-28 | 2017-12-26 | 深圳市泰和安科技有限公司 | Optical detector of fire smoke |
| US10989368B2 (en) | 2017-04-13 | 2021-04-27 | Carrier Corporation | Notification device for a surface of a building interior |
| CN112991666A (en) * | 2021-02-08 | 2021-06-18 | 三明学院 | Fire smoke detector, smoke chamber thereof and anti-interference smoke detection method |
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| US4226533A (en) * | 1978-09-11 | 1980-10-07 | General Electric Company | Optical particle detector |
| CN1261433A (en) * | 1997-07-03 | 2000-07-26 | 罗伯特·N·汉伯格 | Allergen detector system and method |
| JP2001133384A (en) * | 1999-11-05 | 2001-05-18 | Shimadzu Corp | Laser diffraction/scatter type particle-size distribution measuring device |
| CN1383107A (en) * | 2001-04-24 | 2002-12-04 | 松下电工株式会社 | Fire detector unit |
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| CN101859469A (en) * | 2010-05-14 | 2010-10-13 | 公安部沈阳消防研究所 | Obscuration-forward scatter composite spot-type photoelectric smoke fire detector and detection method thereof |
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2011
- 2011-01-06 CN CN2011100014566A patent/CN102129755B/en not_active Expired - Fee Related
Patent Citations (6)
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| US4226533A (en) * | 1978-09-11 | 1980-10-07 | General Electric Company | Optical particle detector |
| CN1261433A (en) * | 1997-07-03 | 2000-07-26 | 罗伯特·N·汉伯格 | Allergen detector system and method |
| JP2001133384A (en) * | 1999-11-05 | 2001-05-18 | Shimadzu Corp | Laser diffraction/scatter type particle-size distribution measuring device |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103575658A (en) * | 2012-08-10 | 2014-02-12 | 能美防灾株式会社 | Photoelectric separation type detector |
| CN103366495A (en) * | 2013-07-11 | 2013-10-23 | 合肥工业大学 | Air-breathing high-sensitivity smoke particle detector and application thereof |
| US10989368B2 (en) | 2017-04-13 | 2021-04-27 | Carrier Corporation | Notification device for a surface of a building interior |
| CN107516397A (en) * | 2017-09-28 | 2017-12-26 | 深圳市泰和安科技有限公司 | Optical detector of fire smoke |
| CN112991666A (en) * | 2021-02-08 | 2021-06-18 | 三明学院 | Fire smoke detector, smoke chamber thereof and anti-interference smoke detection method |
| CN112991666B (en) * | 2021-02-08 | 2023-04-28 | 三明学院 | Fire smoke detector, smoke chamber thereof and anti-interference smoke detection method |
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| CN102129755B (en) | 2012-07-04 |
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