GB2089502A - Flame Detector - Google Patents
Flame Detector Download PDFInfo
- Publication number
- GB2089502A GB2089502A GB8135758A GB8135758A GB2089502A GB 2089502 A GB2089502 A GB 2089502A GB 8135758 A GB8135758 A GB 8135758A GB 8135758 A GB8135758 A GB 8135758A GB 2089502 A GB2089502 A GB 2089502A
- Authority
- GB
- United Kingdom
- Prior art keywords
- radiation
- flame detector
- luminescent substance
- flames
- wavelength converter
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 230000005855 radiation Effects 0.000 claims abstract description 76
- 239000004020 conductor Substances 0.000 claims abstract description 15
- 239000013543 active substance Substances 0.000 claims abstract description 8
- 239000000654 additive Substances 0.000 claims abstract description 6
- 230000000996 additive effect Effects 0.000 claims abstract description 6
- YBMRDBCBODYGJE-UHFFFAOYSA-N germanium dioxide Chemical compound O=[Ge]=O YBMRDBCBODYGJE-UHFFFAOYSA-N 0.000 claims abstract description 6
- QDOXWKRWXJOMAK-UHFFFAOYSA-N dichromium trioxide Chemical compound O=[Cr]O[Cr]=O QDOXWKRWXJOMAK-UHFFFAOYSA-N 0.000 claims abstract description 5
- 229910003080 TiO4 Inorganic materials 0.000 claims abstract description 3
- COHDHYZHOPQOFD-UHFFFAOYSA-N arsenic pentoxide Chemical compound O=[As](=O)O[As](=O)=O COHDHYZHOPQOFD-UHFFFAOYSA-N 0.000 claims abstract 3
- 239000000126 substance Substances 0.000 claims description 15
- 230000003595 spectral effect Effects 0.000 claims description 10
- 238000011156 evaluation Methods 0.000 claims description 6
- 230000005670 electromagnetic radiation Effects 0.000 claims description 4
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 2
- 239000000470 constituent Substances 0.000 claims description 2
- 230000004913 activation Effects 0.000 claims 1
- 229910001437 manganese ion Inorganic materials 0.000 claims 1
- 238000001514 detection method Methods 0.000 abstract description 5
- 239000000446 fuel Substances 0.000 abstract description 3
- 239000007788 liquid Substances 0.000 abstract description 3
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 abstract 1
- 229910052593 corundum Inorganic materials 0.000 abstract 1
- 229910001635 magnesium fluoride Inorganic materials 0.000 abstract 1
- 239000013307 optical fiber Substances 0.000 abstract 1
- 150000004760 silicates Chemical class 0.000 abstract 1
- 229910001845 yogo sapphire Inorganic materials 0.000 abstract 1
- 238000010276 construction Methods 0.000 description 6
- 239000001257 hydrogen Substances 0.000 description 4
- 229910052739 hydrogen Inorganic materials 0.000 description 4
- 239000003921 oil Substances 0.000 description 4
- 230000035945 sensitivity Effects 0.000 description 4
- 230000011664 signaling Effects 0.000 description 4
- 238000009826 distribution Methods 0.000 description 3
- 239000000835 fiber Substances 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 238000004020 luminiscence type Methods 0.000 description 3
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- 239000012190 activator Substances 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 230000005284 excitation Effects 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000009434 installation Methods 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 230000006798 recombination Effects 0.000 description 2
- 238000005215 recombination Methods 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 238000013021 overheating Methods 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 230000002688 persistence Effects 0.000 description 1
- SBIBMFFZSBJNJF-UHFFFAOYSA-N selenium;zinc Chemical compound [Se]=[Zn] SBIBMFFZSBJNJF-UHFFFAOYSA-N 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J1/00—Photometry, e.g. photographic exposure meter
- G01J1/58—Photometry, e.g. photographic exposure meter using luminescence generated by light
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N5/00—Systems for controlling combustion
- F23N5/02—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium
- F23N5/08—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium using light-sensitive elements
- F23N5/082—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium using light-sensitive elements using electronic means
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Photometry And Measurement Of Optical Pulse Characteristics (AREA)
Abstract
A detector head 1 is equipped with an ultraviolet filter 3 and a wavelength converter 4 which at about 250 nm converts ultraviolet radiation into longer wave radiation above 600 nm. this longer wave radiation is transmitted via a radiation conductor (optical fiber) 6 to a radiation receiver 8 arranged remote from the detector head. This arrangement enables a selective detection of both liquid fuel flames and gas flames. The detection is not influenced in its functional reliability by background temperature radiation and not influenced by the action of heat. Examples of short afterglow phosphors for use in the wavelength converter are given, e.g. Mn-doped silicates, MgO activated with Mn<4+> and containing As2O5, TiO4 or GeO2 or a further additive of MgF2 or Al2O3 activated with Cr2O3, or of the type containing 3Cd3(PO4)2.CdCl2-0.05 Mn<2+> as the active substance. <IMAGE>
Description
SPECIFICATION Luminescenz-flame-detector The present invention relates to a new and improved construction of flame detector, wherein in the presence of flames electromagnetic radiation is conducted to a radiation receiver by at least one radiation conductor arrangement, and the radiation receiver is connected to an evaluation and signalling circuit.
Flame detectors of this type can serve, for instance, for determining whether a flame is present in a combustion or furnace installation and for signalling the absence of a flame therein, or they can be used with fire alarm systems for detecting an undesired flame formation and triggering an alarm signal. This is achieved by detecting the electromagnetic radiation emanating from the flames by means of a radiation receiver. There is connected to the radiation receiver a suitable evaluation and signalling circuit as disclosed, for instance, in
United States Patent Nos. 3,820,097,3,996,221 and 3,940,753.
Prior art flame detector arrangements of this type have the disadvantage that the radiation receiver is exposed to a thermal load which is caused by the thermal radiation emanating from the flames. With undue or impermissible heating of the radiation detector such flame detector systems can become inoperative, so that no correct flame signal is generated.
In order to avoid undue heating of the radiation receiver it is known, for instance according to
German Patent No. 1,473,226 or German Patent
No. 2,834,925 to use a radiation conductor, also known in the art as fibre optics, for conducting the electromagnetic radiation, which emanates from a flame to the radiation receiver which is arranged externally of the radiation range of the flames and protected from the influence of heat. While there is thus achieved a reliable protection of the radiation receiver against overheating and the functional reliability thereof is improved, nonetheless there must be tolerated the disadvantage that conventional radiation conductors or fibre optics are preferably suitable for light of long wavelength or in the near infrared region.The employment of such flame detector arrangements which work with radiation conductors thus is limited to the detection or the signalling of flames having a high proportion of light or infrared radiation in the spectrum, for instance oil flames or liquid fuel flames. Thus, it is unfavorable that, for instance, in furnaces, background temperature radiation is located in the same spectral region, so that for differentiating such radiation from flames there are required complicated evaluation circuits.
With flame detection arrangements of this type gas flames, especially hydrogen or flames containing a high proportion of hydrogen, can hardly or only insufficiently be detected, since the light and infrared proportion thereof is hardly any different from the background radiation. Such nearly invisible flames only can be detected in the furnace by means of the radiation in the ultraviolet spectral region in the neighbourhood of about 250 nm. In Figure 2 this characteristic difference is illustrated by means of typical spectral distributions in various flames. The graph
A is an example of an oil flame having a continuum which reaches from ultraviolet to infrared, while graph B is a hydrogen flame having the maximum in the ultraviolet region at 250 nm.
In order to detect flames of all types, including gas flames, it was heretofore necessary to employ special ultraviolet-sensitive radiation receivers.
For this purpose there were used, as a rule, discharge tubes disclosed, for instance, in United
States Patent No. 3,544,792 or United States
Patent No. 3,553,665. Upon excitation with ultraviolet radiation in the region of 200 to 290 nm, such discharge tubes fire and release a signal.
However, ultraviolet-sensitive discharge tubes of this type are unreliable components which are prone to disturbances, and cannot withstand the influence of heat or thermal loads.
Therefore, it is a primary object of the present invention to provide a new and improved construction of flame detector which is not associated with the aforementioned drawbacks and shortcomings of the prior art.
Another important object of the present invention is to provide a new and improved construction of flame detector which is capable of detecting all types of flames independently of the type of combusted material.
A further important object of the present invention aims at providing a new and improved construction of flame detector which does not respond to mere background temperature radiation.
It is yet another important object of the present invention to provide a new and improved construction of flame detector which, even under the influence of thermal radiation operates in a functionally reliable, trouble-free and sensitive manner.
Now in order to implement these objects and others which will become more readily apparent as the description proceeds, the invention contemplates arranging a wavelength converter at the input of the radiation conductor. This wavelength converter converts the ultraviolet radiation emanating from flames into longer wave radiation which is conducted to the radiation receiver.
The invention will be better understood and objects other than those set forth above will
become apparent when consideration is given to the following detailed description thereof. Such
description makes reference to the annexed
drawings wherein:
Figure 1 is an exemplary embodiment of flame detector arrangement according to the invention; and
Figure 2 is a graphic illustration of various
spectral distributions for the purpose of explaining the present invention.
Describing now the drawings, with the flame detector arrangement according to the exemplary embodiment of Figure 1 there is provided a detector head 1 which contains a temperatureresistant housing 2. This housing 2 is provided with a radiation entry window or opening 3 which faces the flames and allows the radiation emanating from the flames to enter the housing 2. The radiation entry window or inlet opening 3 can be constructed, for instance, as an ultraviolet filter of the commercially available type UG 11, fabricated by the well known West German firm
Schott, Jenaer Glaswerk, located at Mainz, West
Germany, and essentially only allows infrared radiation between 200 and 300 nm to enter the housing 2.
Inside the housing 2 there is arranged a wavelength converter 4 which is constructed and selected such that upon excitation with ultraviolet radiation located in the aforementioned region of 200 to 300 nm it emits radiation of longer wavelength, for instance radiation having a wavelength of over 600 nm up to near infrared.
Thus, as soon as ultraviolet radiation impinges upon the detector head 1 the wavelength converter 4 emits radiation in the region of longwave light or near infrared.
In principle, there are suitable for forming the wavelength converter 4 a number of known luminescent or phosphorescent substances, such as conventional phosphors with recombination luminescence of the ZnS or the ZnSe type.
However, for differentiating the flame radiation from spurious radiation, as is frequently required, there is needed an evaluation of the flicker behaviour in a given flicker frequency range, and in such case the luminescence persistence time or afterflow time of phosphors with recombination luminescence often is too long. According to an advantageous further construction it therefore has been found to be particularly beneficial to use phosphors having a short afterglow time, for instance phosphors with activator ions. It has been found that especially phosphors containing
Mn2+ as an additive are capable of converting radiation of about 250 nm into radiation of above 600 nm with particularly good efficiency.As suitable phosphors there have been found phosphors of the composition (xZnO- yBeO)2SiO-zMn2+, especially the phosphor (0.8ZnO.0.1 BeO)2Si02-0.09Mn2+. in the foregoing formula x, y and z represent the proportion by weight of the constituents.further suitable luminescent substances of the same type are: P--Zn,SiO,,-O.O SO -0.012Mn2+.Phosphors which
2 4 have been activated with other activator ions have also been found to be equally suitable, for instance MgO which has been activated with
Mn4+ and containing a selective additive of A520s,TiO4 or GeO2, or, as the case may be, a further selective additive of Mg F2, or Awl203 which
has been activated with Cr2O3. The luminescent substance also may be of the type contining 3Cd3(P04)2.CdCl2-O.05Mn2+ as the active substance.
The long-wave radiation emitted by these luminescent substances is conducted to the input 5 of a radiation conductor 6, is transmitted therein and at the output 7 of the radiation conductor 6 is received by a radiation receiver 8.
As the radiation conductors 6 there can be beneficially used commercially available optical fibres, e.g. conventional step index fibres or graded index fibres. The radiation conductor arrangement 6 also can be composed of a bundle or bunch of fibres instead of an individual fibre.
Likewise, the radiation conductor arrangement 6 can comprise branch points 9 of conventional and commercially available design and from which branch points 9 further light conductors 6' branch off to further detector heads 1' for monitoring or supervising several regions or areas at the same time.
In principle, there can be used as the radiation receiver 8 any desired photodetector which has sufficient sensitivity in the spectral region of visible light and near infrared. It has been found to be advantageous to use, for instance, silicon photodiodes of the types SHS, SGD and YAG (available from E 8 G Electro-Optics, located at 35 Congress Street, Salem, Massachussets), which reach a sensitivity maximum at a wavelength between 600 and 1000 nm.
Connected to the radiation receiver 8 is a discriminator and amplifier circuit 9 and a signal circuit 10. These circuits can be constructed in conventional manner as described in the initially mentioned prior art patents and can be adapted to the desired purpose or field of application.
The mode of operation of the flame detector arrangement according to the invention will be recognized from the spectral distributions illustrated in Figure 2. The graph A is a typical spectrum of an oil flame which has a continuum reaching from ultraviolet at 200 nm to infrared.
The graph B illustrates a hydrogen flame which, as opposed to the graph A, has a maximum in the ultraviolet region at about 250 nm and weaker radiation in the visible region and in infrared than the oil flame. The diagram indicates that the evaluation of the spectral region in the neighbourhood of 250 nm is particularly favorable in order to detect both flames caused by liquid fuels and flames caused by gases. It is advantageous if the temperature radiator, for instance the furnace background of a combustion installation contains practically no radiation below 300 nm, as schematically indicated by curve C, and thus, does not interfere with the flame detection. This background radiation C is kept way or blocked by means of the filter 3, the radiation permeability of which is represented by curve F and essentially only encompasses the spectral region between 200 and 300 nm, and thus, almost entirely blocks the background radiation C. The radiation which has been transmitted by filter 3 is converted into longer wave radiation of preferably more than 600 nm.
The spectral sensitivity of the radiation receiver 8, as illustrated by curve S, is chosen such that it
reaches a maximum between 600 and 1000 nm,
and thus, is optimumly adapted to the wavelength
converter 4.
In the heretofore described manner there can thus be achieved a flame detector arrangement which enables selectively detecting flames of various types and operating with optimum
sensitivity, while being constructed in a simple
manner and with components which are not prone to disturbances. Thus, the influence of thermal radiation can be minimized.
While there are shown and described preferred embodiments of the present invention, it is to be distinctly understood that the invention is not limited thereto but may be embodied and practiced within the scope of the following claims.
Claims (14)
1. In a flame detector wherein upon the presence of flames electromagnetic radiation is conducted by at least one radiation conductor to a radiation receiver which is connected to an evaluation and signal circuit, the improvement which comprises:
a wavelength converter arranged at an inlet of the radiation conductor; and
said wavelength converter serving for converting ultraviolet radiation emanating from the flames into longer wave radiation and delivering the same to said radiation conductor.
2. The flame detector as defined in claim 1, further including:
an ultraviolet filter arranged forwardly of said wavelength converter.
3. The flame detector as defined in claim 1 or 2, wherein:
said wavelength converter contains a luminescent substance; and
said luminescent substance being activatable by ultraviolet radiation.
4. The flame detector as defined in claim 3, wherein:
said luminescent substance is activatable by ultraviolet radiation in the spectral region of about 250 nm for emitting longer wave radiation.
5. The flame detector as defined in claim 4, wherein:
said luminescent substance, upon activation with ultraviolet radiation, emitting radiation having a wavelength of more than 600 nm.
6. The flame detector as defined in claim 3, wherein:
said luminescent substance comprises a phosphor containing activator-ions.
7. The flame detector as defined in claim 6, wherein:
said activator-ions comprise double-fold positively charged manganese ions (Mn2+).
8. The flame detector as defined in claim 7, wherein:
said luminescent substance contains (xZnO.yBeO)2SiO2-zMn2+ constituting an active substance, wherein x, y and z represent the proportion by weight of the constituents.
9. The flame detector as defined in claim 8, wherein:
said luminescent substance contains (0.8ZnO.0. 1 BeO)2Si02-0.09Mn2+) constituting the active substance.
10. The flame detector as defined in claim 7, wherein:
said luminescent substance contains p- Zn2SiO4-0.01 2Mn2+ constituting an active substance.
11. The flame detector as defined in claim 7, wherein:
said luminescent substance contains 3Cd3(P04)2.CdCl2-0.05Mn2+ constituting an active substance.
1 2. The flame detector as defined in claim 7, wherein:
said luminescent substance contains as an active substance MgO activated by Mn4+ and an additive selected from the group essentially consisting of As205, TiO4 and GeO2 and optionally a further additive of Mg F2.
13. The flame detector as defined in claim 6, wherein:
said luminescent substance contains as active substance Awl203 activated by Cr203.
14. A flame detector substantially as herein described with reference to the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CH899080 | 1980-12-05 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2089502A true GB2089502A (en) | 1982-06-23 |
| GB2089502B GB2089502B (en) | 1984-05-10 |
Family
ID=4347113
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8135758A Expired GB2089502B (en) | 1980-12-05 | 1981-11-26 | Flame detector |
Country Status (3)
| Country | Link |
|---|---|
| DE (1) | DE3141277A1 (en) |
| FR (1) | FR2496879A1 (en) |
| GB (1) | GB2089502B (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2198530A (en) * | 1986-12-08 | 1988-06-15 | Gen Electric Co Plc | Radiation meters |
| WO1988006279A1 (en) * | 1987-02-11 | 1988-08-25 | The Secretary Of State For Defence In Her Britanni | Ultraviolet radiation detector |
| EP0290167A2 (en) * | 1987-05-02 | 1988-11-09 | Thomas Swan And Co., Ltd. | Improvements in or relating to the detection of ultraviolet radiation |
| WO1989012774A1 (en) * | 1988-06-23 | 1989-12-28 | Allied-Signal Inc. | Solid-state optical flame detector |
| EP0896663A1 (en) * | 1996-04-29 | 1999-02-17 | Petrometrix Ltd. | Spectral information transmission through communication optical fibers |
| EP1312860A1 (en) * | 2000-08-22 | 2003-05-21 | Ebara Corporation | Method and device for combustion type exhaust gas treatment |
| US7846350B2 (en) | 2006-09-12 | 2010-12-07 | National Chiao-Tung University | Highly saturated red-emitting Mn(IV) activated phosphors and method of fabricating the same |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102021100756A1 (en) | 2021-01-15 | 2022-07-21 | Vaillant Gmbh | Method and arrangement for observing flames in a heating device that can be operated with hydrogen or fuel gas containing hydrogen |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE701087C (en) * | 1938-05-25 | 1941-01-08 | Patra Patent Treuhand | Electric discharge lamp or fluorescent tube filled with noble gases and mercury and a luminophore layer excited by the mercury radiation |
| GB766150A (en) * | 1952-11-20 | 1957-01-16 | Gen Electric Co Ltd | Improvements in or relating to low pressure fluorescent electric discharge lamps |
| FR1213203A (en) * | 1958-01-02 | 1960-03-29 | Philips Nv | High pressure mercury vapor discharge tube equipped with a luminescent screen, luminescent substance therefor, and method of preparation thereof |
| DE1211421C2 (en) * | 1963-12-12 | 1973-11-15 | DEVICE FOR SCANNING GOOD THROUGH GOOD | |
| US4037113A (en) * | 1975-04-11 | 1977-07-19 | Forney Engineering Company | Flame detector |
| US4061922A (en) * | 1976-05-17 | 1977-12-06 | John S. Ewald | Ultraviolet sensing device |
| DE2834925A1 (en) * | 1978-08-09 | 1980-02-21 | Grecon Greten Gmbh & Co Kg | Measuring device for fire alarm - has light conductor probe coupled to transducer connected to evaluation circuit |
-
1981
- 1981-10-17 DE DE19813141277 patent/DE3141277A1/en not_active Withdrawn
- 1981-11-25 FR FR8122036A patent/FR2496879A1/en not_active Withdrawn
- 1981-11-26 GB GB8135758A patent/GB2089502B/en not_active Expired
Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2198530A (en) * | 1986-12-08 | 1988-06-15 | Gen Electric Co Plc | Radiation meters |
| US4935631A (en) * | 1986-12-08 | 1990-06-19 | The General Electric Company, P.L.C. | Radiation meters |
| GB2198530B (en) * | 1986-12-08 | 1991-04-17 | Gen Electric Plc | Radiation meters |
| WO1988006279A1 (en) * | 1987-02-11 | 1988-08-25 | The Secretary Of State For Defence In Her Britanni | Ultraviolet radiation detector |
| EP0290167A2 (en) * | 1987-05-02 | 1988-11-09 | Thomas Swan And Co., Ltd. | Improvements in or relating to the detection of ultraviolet radiation |
| EP0290167A3 (en) * | 1987-05-02 | 1990-11-14 | Thomas Swan And Co., Ltd. | Improvements in or relating to the detection of ultraviolet radiation |
| WO1989012774A1 (en) * | 1988-06-23 | 1989-12-28 | Allied-Signal Inc. | Solid-state optical flame detector |
| EP0896663A1 (en) * | 1996-04-29 | 1999-02-17 | Petrometrix Ltd. | Spectral information transmission through communication optical fibers |
| EP0896663A4 (en) * | 1996-04-29 | 2000-03-08 | Petrometrix Ltd | Spectral information transmission through communication optical fibers |
| EP1312860A1 (en) * | 2000-08-22 | 2003-05-21 | Ebara Corporation | Method and device for combustion type exhaust gas treatment |
| EP1312860A4 (en) * | 2000-08-22 | 2007-02-28 | Ebara Corp | Method and device for combustion type exhaust gas treatment |
| US7846350B2 (en) | 2006-09-12 | 2010-12-07 | National Chiao-Tung University | Highly saturated red-emitting Mn(IV) activated phosphors and method of fabricating the same |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2496879A1 (en) | 1982-06-25 |
| GB2089502B (en) | 1984-05-10 |
| DE3141277A1 (en) | 1982-06-16 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |