(19) & (11) EP 1 609 170 B1 (12) EUROPEAN PATENT SPECIFICATION (45) Date of publication and mention (51) Int Cl.: of the grant of the patent: H01J 61/28 (2006.01) H01J 61/72 (2006.01) 05.05.2010 Bulletin 2010/18 C02F 1/32 (2006.01) (21) Application number: 04758635.9 (86) International application number: PCT/US2004/009814 (22) Date of filing: 31.03.2004 (87) International publication number: WO 2004/089429 (21.10.2004 Gazette 2004/43) (54) GERMICIDAL LOW PRESSURE MERCURY VAPOR DISCHARGE LAMP WITH AMALGAM LOCATION PERMITTING HIGH OUTPUT KEIMTÖTENDE NIEDERDRUCK-QUECKSILBERDAMPFENTLADUNGSLAMPE MIT AMALGAMANORDNUNG ZUR ERMÖGLICHUNG EINER HOHEN AUSGANGSLEISTUNG LAMPE A DECHARGE A VAPEUR DE MERCURE BASSE PRESSION GERMICIDE A EMPLACEMENT D’AMALGAME PERMETTANT D’OBTENIR UN RENDEMENT ELEVE (84) Designated Contracting States: (56) References cited: AT BE BG CH CY CZ DE DK EE ES FI FR GB GR GB-A- 2 203 283 JP-A- 1 117 265 HU IE IT LI LU MC NL PL PT RO SE SI SK TR JP-A- 5 290 806 US-A- 5 352 359 US-A- 5 352 359 US-B1- 6 310 437 (30) Priority: 03.04.2003 US 406759 US-B1- 6 337 539 US-B1- 6 456 004 (43) Date of publication of application: • BLOEM J ET AL: "SOME NEW MERCURY 28.12.2005 Bulletin 2005/52 ALLOYS FOR USE IN FLUORESCENT LAMPS" JOURNAL OF THE ILLUMINATING (73) Proprietor: Light Sources, Inc. ENGINEERING SOCIETY, ILLUMINATING Orange, CT 06477 (US) ENGINEERING SOCIETY. NEW YORK, US, vol. 6, no. 3, 1 April 1977 (1977-04-01), pages 141-147, (72) Inventor: PIROVIC, Arpad, L. XP000615021 ISSN: 0099-4480 Woodbridge, CT 06525 (US) (74) Representative: Grünecker, Kinkeldey, Stockmair & Schwanhäusser Anwaltssozietät Leopoldstrasse 4 80802 München (DE) Note: Within nine months of the publication of the mention of the grant of the European patent in the European Patent Bulletin, any person may give notice to the European Patent Office of opposition to that patent, in accordance with the Implementing Regulations. Notice of opposition shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). EP 1 609 170 B1 Printed by Jouve, 75001 PARIS (FR) 1 EP 1 609 170 B1 2 Description smaller than the amalgam pellet are formed between the small tube and the lamp tube, thereby preventing the FIELD OF THE INVENTION pellet from falling when the lamp is positioned vertically. [0004] There is a need for a low pressure mercury va- [0001] The present invention relates generally to low 5 pordischarge germicidal lamp forproducing a high output pressure mercury vapor discharge germicidal lamps of ultraviolet radiation that reduces the possibility of an used to disinfect or purify fluids, and more particularly to amalgam melting or moving out of a desired location dur- a germicidal lamp having a structure permitting high out- ing high loading. put and relatively high temperature operation. 10 SUMMARY OF THE INVENTION BACKGROUND OF THE INVENTION [0005] The present invention relates to a germicidal [0002] Low pressure mercury vapor discharge lamps low pressure mercury vapor discharge lamp as defined are commonly used to generate ultraviolet radiation and in claim 1 for operating under a high load having improved used to irradiate a fluid to kill potentially harmful organ- 15 operation and output. An amalgam is positioned out of isms contained in the fluid. Often, relatively high doses the arc path during operation of the lamp. An amalgam of ultraviolet radiation are required. The necessary rela- container is positioned behind the electrode in a relatively tively high doses of ultraviolet radiation typically require cool location or cold spot. The amalgam container is the use of multiple germicidal lamps. The use of multiple open, permitting the surface of the amalgam to be ex- germicidal lamps increases expenses, as well as main- 20 posed to the interior space of the lamp, yet restricted to tenance. Therefore, it is desirable to use fewer higher prevent the amalgam from moving out of position from output germicidal lamps. However, producing a high out- behind the electrode where it is out of the arc path. put germicidal lamp is not without difficulties. During op- [0006] One embodiment comprises a germicidal lamp eration of a low pressure mercury vapor discharge lamp, system having a plurality of elongated lamps held verti- the vapor pressure of the mercury greatly affects lamp 25 cally within a fluid. The amalgam container holds amal- operation. A predetermined vapor pressure is desirable gam in a location behind the electrode preventing the for efficient operation of the lamp. However, under heavy amalgam from moving out of position during high loading loads used to produce a high output, mercury vapor pres- of the germicidal lamps. The positioning of the amalgam sure may increase reducing the efficiency and operation in a cooler location makes possible the higher loading of of the lamp. Amalgam has often been used to control the 30 the germicidal lamp. mercury vapor pressure within the lamp, permitting the [0007] Accordingly, it is an object of the present inven- lamp to operate more efficiently. However, the higher tion to provide a high output germicidal lamp capable of temperatures occurring at high loading of the lamp often operating at high wall loads. cause the amalgam to melt. If the amalgam melts, it will [0008] It is another object of the present invention to move out of position and could make contact with an35 provide a germicidal lamp that is capable of using amal- electrode and cause possible shorting or ineffective op- gams that may melt at the internal operating temperature eration of the lamp. of the germicidal lamp. [0003] A germicidal lamp using an amalgam is dis- [0009] It is another object of the present invention to closed in Patent Cooperation Treaty international appli- provide a germicidal lamp that can effectively operate cation No. PCT/DE96/00647 having a publication40 over a wide temperature range. number of WO96/31902 and published October 10, [0010] It is an advantage of the present invention that 1996, entitled "Low Pressure Mercury Vapor Discharge the germicidal lamp can be held vertically during opera- Lamp". Therein disclosed is a low pressure mercury va- tion. por discharge lamp having an amalgam placed along the [0011] It is another advantage of the present invention inner wall between the electrodes. The lamp tube is in 45 that the amalgam is held in a cooler location outside of mechanical contact with a cooler on the outside of the the arc path or positive column. lamp adjacent the location of the amalgam. While this [0012] It is a feature of the present invention that the lamp structure is helpful in keeping the amalgam cool amalgam is held in a position behind an electrode. and therefore permitting higher loading of the lamp to [0013] It is another feature of the present invention that improve output, the amalgam could still melt causing the 50 a container is used to prevent the amalgam from moving amalgam to move out of position. This is particularly prob- out of a desired position. lematic in applications where the lamp is held vertically [0014] These and other objects, advantages, and fea- rather than horizontally, which could result in the amal- tures will become readily apparent in view of the following gam falling downward onto one of the electrodes. JP 05 more detailed description. 290 806 discloses a fluorescent lamp comprising a small 55 tube where an amalgam pellet is placed and wherein the BRIEF DESCRIPTION OF THE DRAWINGS small tube is formed in the stem which is sealed with the end of the lamp tube. A plurality of communicating holes [0015] 2 3 EP 1 609 170 B1 4 Fig. 1 schematically illustrates a plurality of germi- loading may be greater than 250 milliwatts per centimeter cidal lamps and a germicidal system according to squared. Comparatively, a conventional fluorescent the present invention. lamp is generally only operated at a wall load of about Fig. 2A is a partial view illustrating one end of a ger- 100 milliwatts per centimeter squared. During high cur- micidal lamp according to the present invention. 5 rent operation, with the resulting high wall load, the in- Fig. 2B illustrates the end portion of the germicidal ternal temperature of the lamp may increase to greater lamp illustrated in Fig. 2A rotated 90°. than 140° centigrade. At these temperatures, the mercu- Fig. 3A is a partial view illustrating one end of a ger- ry vapor pressure within the germicidal lamp increases micidal lamp according to another embodiment of to unacceptable levels. In order to keep the mercury va- the present invention. 10 por pressure within predetermined limits for effective op- Fig. 3B is an enlarged view illustrating an amalgam eration of the lamps, amalgams are used to absorb and container of the embodiment illustrated in Fig. 3A. release mercury as required to maintain efficient opera- tion. However, at high temperatures, the amalgam may DETAILED DESCRIPTION OF THE PREFERRED EM- melt, limiting their effectiveness and causing them to BODIMENTS 15 move out of position within the germicidal lamp. The present invention positions the amalgam outside of the [0016] Fig. 1 schematically illustrates a germicidal sys- arc path or outside of the positive column at a location tem 10 of the present invention. A container 12 holds a behind the electrode in a cooler spot. The amalgam is fluid 14 therein. The fluid may be waste water, air, or any positioned at a location where the internal temperature other fluid type material that is to be purified or disinfected 20 or wall temperature of the germicidal lamp is less than using ultraviolet radiation.