US3505553A - Radio-interference-free low-pressure mercury-vapor lamp - Google Patents

Radio-interference-free low-pressure mercury-vapor lamp Download PDF

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Publication number
US3505553A
US3505553A US634222A US3505553DA US3505553A US 3505553 A US3505553 A US 3505553A US 634222 A US634222 A US 634222A US 3505553D A US3505553D A US 3505553DA US 3505553 A US3505553 A US 3505553A
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United States
Prior art keywords
interference
pressure mercury
low
lamp
lamps
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Expired - Lifetime
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US634222A
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English (en)
Inventor
Pierre Theodoor Johan Piree
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US Philips Corp
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US Philips Corp
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Publication date
Priority claimed from NL6606479A external-priority patent/NL6606479A/xx
Priority claimed from NL6614550A external-priority patent/NL6614550A/xx
Application filed by US Philips Corp filed Critical US Philips Corp
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Publication of US3505553A publication Critical patent/US3505553A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/02—Details
    • H01J61/04—Electrodes; Screens; Shields
    • H01J61/06—Main electrodes
    • H01J61/067—Main electrodes for low-pressure discharge lamps
    • H01J61/0675—Main electrodes for low-pressure discharge lamps characterised by the material of the electrode
    • H01J61/0677—Main electrodes for low-pressure discharge lamps characterised by the material of the electrode characterised by the electron emissive material

Definitions

  • a low-pressure mercury-vapor discharge lamp employing cathodes having an emissive material containing boron and/0r certain borides to reduce radio interference, i.e., to suppress emission of electromagnetic radiations which would interfere with other telecommunication signals.
  • This invention relates to low-pressure mercury-vapor discharge lamps having a discharge space containing two thermionic cathodes each comprising a carrier coated with electron-emissive material.
  • Lamps of the above mentioned kind intended for illumination purposes are usually formed by rectilinear or circular glass tubes having the inner side coated with a luminescent material which converts the ultra-violet radiation produced in the discharge into light.
  • a luminescent material which converts the ultra-violet radiation produced in the discharge into light.
  • Such lamps have been found to be very important, inter alia because of their capacity to provide a considerable amount of lumens per watt of energy supplied.
  • the color of the light radiated by the lamps may be varied within very wide limits and thus matched to any purpose desired.
  • a disadvantage of these low-pressure mercury-vapor discharge lamps which has been known for a long time is that, in addition to emitting light, they also produce and emit electromagnetic oscillations having a wavelength such as to cause interference with electromagnetic telecommunication signals, for example, radio signals. Although the level of the interference signals produced by the lamp is not high in an absolute sense, the interference may be very troublesome with Weak signals.
  • electromagnetic oscillations produced in the lamps may exert their interfering influence along two paths. One of these paths is the direct radiation. This may be decreased, for example, by electrically shielding the lamps, i.e., by arranging them in a grounded metal cage.
  • this cage will usually be made of a material, for example, metal gauze, which is permeable to the desired radiation of light.
  • the second path along which the interfering oscillations may exert their influence on apparatus for producing or observing telecommunication signals extends through the supply leads. If both the lamp and the apparatus are connected to the same source of supply, for example the current supply mains, the connection is electrically conductive or capacitive and hence the transfer of interference is considerable. Apart from this direct transfer there is a transfer of interference due to the current-supply wires of the lamp connected to the mains emitting interference radiation. In order to inhibit the two last-mentioned interference influences, it has been suggested to employ electrical filters between the lamp and the current supply mains.
  • Such filters may be combined, for example, with the current-stabilizing elements, such as choke coils, which are required anyway for feeding low-pressure mercury vapor discharge lamps. It will be evident that such filter elements render the whole installation more complicated and hence more expensive. Furthermore, such steps do not remove the cause of the Patented Apr. 7, 1970 interference and can therefore yield a given result only under certain conditions. If the telecommunication signals to be observed are very weak, it is necessary either to use very complicated filters or accept a low, though oer tain, interference level. Such filters are naturally no remedy against the interference resulting from the abovementioned direct radiation by the lamp itself.
  • this negative space charge arises due to the fact that, during the passage of current in the discharge space the highly concentrated emission spot of high temperature which exists on the cathode remains so hot as the alternating voltage passes through zero that more electrons are emitted than is necessary at this moment for maintaining the discharge. Consequently, irregular oscillations of charge carriers are produced in the said area.
  • the resulting variations in the electromagnetic field give rise to part of the above-mentioned interference, which will be referred to hereinafter as re-ignition interference.
  • the frequencies of this interference lie in the range between 550 kc./sec. and 1400 kc./sec.
  • oscillations occur when an electrode acts as an anode. They will be referred to hereinafter as anode interference.
  • the frequencies of this interference lie in the range between 160 kc./ sec. and 240* kc./sec.
  • Steps have previously been suggested for decreasing the above-mentioned interference.
  • it has been proposed to bring about an improvement by modifying the structure of the cathode, for example, by varying the dimensions of the carrier for the emissive material which is usually a heating cOil.
  • the emissive material With an amount of finely-divided material, for example carbon, iron, platinum, tungsten, palladium, molybdenum, tantalum or compounds thereof which are electrically conductive. These are added in comparatively large amounts, in certain cases even from 50 to by Weight of the amount of emissive material.
  • finely-divided material for example carbon, iron, platinum, tungsten, palladium, molybdenum, tantalum or compounds thereof which are electrically conductive.
  • a principal object of the invention is to reduce the intensity of the interference oscillations produced by a low-pressure mercury-vapor discharge lamp, especially of the re-ignition interference, but while avoiding the abovementioned drawbacks.
  • a low-pressure mercury vapor discharge lamp has a discharge space containing two thermionic electrodes each consisting of a support which is coated with a thin layer of electron-emitting material containing one or more alkaline-earth oxides mixed With boron and/ or at least one metallic boride which is capable of reducing the emission of unwanted electromagnetic radiations in a quantity which is from 0.1% to 15% of the quantity by weight of alkaline-earth oxide.
  • Such borides are those of elements in the second, fourth, fifth, sixth and seventh columns of the Periodic Table of the Elemerits, and those of lanthanide and actinide series.
  • tungsten, tantalum, and manganese are especially suitable for the above mentioned purpose. When added in comparatively small percentages, these borides cause a strong decrease in interference level and small decrease in the specific light flux. Tantalum boride is preferred but tungsten monoboride gives in addition a very small reduction in the specific light flux.
  • the grain size of the particles of the added materials is preferably chosen to be not greater than 30 times the mean grain size of the particles of emissive material. Very satisfactory results are obtained with a grain size which is smaller than 15 times the mean grain size of the emissive particles.
  • the quantity of added material must preferably be from 0.1% to 10% of the amount by weight of the emissive material. In fact, a satisfactory compromise is then reached between the decrease in interference oscillations and the decline in specific light efliciency.
  • the electrodes in a low-pressure mercury-vapor discharge lamp according to the invention preferably also contain a quantity of zirconium mixed with the emissive material.
  • a quantity of zirconium mixed with the emissive material is known per se to reduce the blackening of the ends of the lamp as the result of disintegration of the electrodes.
  • the quantity of zirconium is preferably from 1% to 5% of the amount by weight of emissive material.
  • the lamp as shown in the drawing, comprises an envelope 1 filled with mercury vapor and a noble gas such as neon.
  • a noble gas such as neon.
  • the inner wall of the envelope is coated with a luminescent material 2 which converts the radiation produced by an electrical discharge radiation.
  • Cathodes 3 and 4 connected to a power source (not shown), provide an electrical discharge since they are covered with an electron emissive material 5 which consists of alkaline earth oxides mixed with a metallic boride which suppresses the emission of unwanted electromagnetic radiations.
  • these cathodes consisted of 'a coiled tungsten wir coated with a mixture of barium carbonate, calcium carbonate, strontium carbonate, zirconium and tungsten monoboride.
  • the quantities of the carbonates of this mixture were chosen to be such that the weight ratio BaCo :CaCO :SrCO was equal to 8:5 :7.
  • the quantity of zirconium was 3% by weight of the quantity of carbonates.
  • the amount of tungsten monobride was varied. In the table given below, three percentages are specified with respect to the total quantities by weight of the carbonates and the zirconium.
  • the lamps according to the example were completed in quite the normal manner, the cathodes, inter alia, being heated, as a result of which the carbonates decomposed into oxides.
  • the lamps were then set into operation in an experimental set-up and the level of interference signals transmitted by the lamps at various frequencies, which are specified in the table, was measured.
  • the intensity of these interference levels was compared with the intensity of the interference level of a lamp which diifered from the lamps according to the example only in that no tungsten monoboride was present on the electrodes.
  • the table shows the differences with respect to these reference lamps in db.
  • the table also gives measured results of lamps which were manufactured exactly in accordance with the above example but in which other borides or the element boron through the mercury vapor to a more pleasing visible 40 it lf was d i th specified o t TAB LE Difierence Interference Decrease Level 11 b Specific Light Percent output I by 550 1,000 1, 400 in Addltion Used Weight kc./see. Ire/see. kcJsec. percent Boron 0.3 8 7 -7.-5 1 Boron oxide 0. 3 8 7. 5 -8 0.8 2.5 11 as -12 2.5 Chromium diboride- 0. 3 -8 -14. 5 -15 1 2. 5 15. 5 19. 5 -18. 5 2. 9 4J1 -16 -20. 5 -19. 5 4.1 Tungsten monoboride 0.
  • a low-pressure mercury-vapor discharge lamp comprising an envelope filled with an ionizable medium defining a discharge space, a pair of spaced thermionic electrodes within said discharge space, each of said electrodes comprising a support which is coated with a thin layer of electron-emissive material containing at least one alkaline-earth oxide, said emissive material being mixed with, from 0.1% to 15% of the amount by weight of alkaline-earth oxide, a boron-containing material capable of suppressing unwanted electromagnetic radiations during operation.
  • a low-pressure mercury-vapor discharge lamp as claimed in claim 1 in which the emissive layer in addition to the boron-containing material contains from 1% to 5% of zirconium of the quantity by weight of emissive material.

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  • Discharge Lamp (AREA)
  • Solid Thermionic Cathode (AREA)
  • Luminescent Compositions (AREA)
  • Vessels And Coating Films For Discharge Lamps (AREA)
US634222A 1966-05-12 1967-04-27 Radio-interference-free low-pressure mercury-vapor lamp Expired - Lifetime US3505553A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL6606479A NL6606479A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1966-05-12 1966-05-12
NL6614550A NL6614550A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1966-10-15 1966-10-15

Publications (1)

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US3505553A true US3505553A (en) 1970-04-07

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US634222A Expired - Lifetime US3505553A (en) 1966-05-12 1967-04-27 Radio-interference-free low-pressure mercury-vapor lamp

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US (1) US3505553A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
AT (1) AT279735B (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
BE (2) BE698366A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
CH (2) CH464354A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
DE (2) DE1589247B2 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
ES (2) ES340339A1 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
FR (2) FR1522814A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
GB (2) GB1191463A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
NO (1) NO118120B (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
SE (2) SE305031B (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5391523A (en) * 1993-10-27 1995-02-21 Marlor; Richard C. Electric lamp with lead free glass
US5654606A (en) * 1994-11-08 1997-08-05 U.S. Philips Corporation Low-pressure discharge lamp having metal and ceramic electrodes
US5675214A (en) * 1994-09-21 1997-10-07 U.S. Philips Corporation Low-pressure discharge lamp having hollow electrodes
US5686789A (en) * 1995-03-14 1997-11-11 Osram Sylvania Inc. Discharge device having cathode with micro hollow array
US5856726A (en) * 1996-03-15 1999-01-05 Osram Sylvania Inc. Electric lamp with a threaded electrode
US5982088A (en) * 1996-06-12 1999-11-09 Tdk Corporation Ceramic cathode fluorescent discharge lamp
EP1286378A1 (en) * 2001-08-22 2003-02-26 General Electric Company Low volatility slurry for emission mix powder

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4321503A (en) * 1978-11-06 1982-03-23 Westinghouse Electric Corp. HID Lamp electrode comprising barium-calcium niobate or tantalate
JPS63141252A (ja) * 1986-12-02 1988-06-13 Hitachi Ltd 低圧放電灯
US4910431A (en) * 1987-04-24 1990-03-20 W. C. Heraeus Gmbh Hydrogen discharge ultraviolet light source or lamp, and method of its manufacture
DE3713704A1 (de) * 1987-04-24 1988-11-03 Heraeus Gmbh W C Wasserstoff-entladungslampe und verfahren zu ihrer herstellung
DE3715375C1 (de) * 1987-05-08 1988-10-13 Heraeus Gmbh W C Wasserstoff-Entladungslampe

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2639399A (en) * 1950-03-31 1953-05-19 Gen Electric Electron emitter
US2878411A (en) * 1955-03-21 1959-03-17 Chromatic Television Lab Inc Color television display screen
US2959702A (en) * 1958-07-02 1960-11-08 Westinghouse Electric Corp Lamp and mount
US3027480A (en) * 1958-12-15 1962-03-27 Raytheon Co Electron discharge device cathodes
US3389285A (en) * 1964-09-08 1968-06-18 Int Standard Electric Corp Grid electrode having a barrier layer of metal carbide and a surface coating of metal boride thereon
US3427491A (en) * 1966-04-20 1969-02-11 Matsushita Electronics Corp Discharge tube
US3427492A (en) * 1966-04-20 1969-02-11 Matsushita Electronics Corp Discharge tube satisfactorily low in radio-interfering noise

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2639399A (en) * 1950-03-31 1953-05-19 Gen Electric Electron emitter
US2878411A (en) * 1955-03-21 1959-03-17 Chromatic Television Lab Inc Color television display screen
US2959702A (en) * 1958-07-02 1960-11-08 Westinghouse Electric Corp Lamp and mount
US3027480A (en) * 1958-12-15 1962-03-27 Raytheon Co Electron discharge device cathodes
US3389285A (en) * 1964-09-08 1968-06-18 Int Standard Electric Corp Grid electrode having a barrier layer of metal carbide and a surface coating of metal boride thereon
US3427491A (en) * 1966-04-20 1969-02-11 Matsushita Electronics Corp Discharge tube
US3427492A (en) * 1966-04-20 1969-02-11 Matsushita Electronics Corp Discharge tube satisfactorily low in radio-interfering noise

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5391523A (en) * 1993-10-27 1995-02-21 Marlor; Richard C. Electric lamp with lead free glass
US5675214A (en) * 1994-09-21 1997-10-07 U.S. Philips Corporation Low-pressure discharge lamp having hollow electrodes
US5654606A (en) * 1994-11-08 1997-08-05 U.S. Philips Corporation Low-pressure discharge lamp having metal and ceramic electrodes
US5686789A (en) * 1995-03-14 1997-11-11 Osram Sylvania Inc. Discharge device having cathode with micro hollow array
US5939829A (en) * 1995-03-14 1999-08-17 Osram Sylvania, Inc. Discharge device having cathode with micro hollow array
US6072273A (en) * 1995-03-14 2000-06-06 Osram Sylvania Inc. Discharge device having cathode with micro hollow array
US6346770B1 (en) 1995-03-14 2002-02-12 Osram Sylvania, Inc. Discharge device having cathode with micro hollow array
US6518692B2 (en) 1995-03-14 2003-02-11 Old Dominion University Discharge device having cathode with micro hollow array
US5856726A (en) * 1996-03-15 1999-01-05 Osram Sylvania Inc. Electric lamp with a threaded electrode
US5982088A (en) * 1996-06-12 1999-11-09 Tdk Corporation Ceramic cathode fluorescent discharge lamp
EP1286378A1 (en) * 2001-08-22 2003-02-26 General Electric Company Low volatility slurry for emission mix powder
US6713950B2 (en) 2001-08-22 2004-03-30 General Electric Company Low volatility slurry for emission mix powder

Also Published As

Publication number Publication date
NO118120B (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1969-11-10
GB1191463A (en) 1970-05-13
ES340339A1 (es) 1968-06-01
DE1589247A1 (de) 1970-04-09
DE1589247B2 (de) 1976-04-15
FR1522815A (fr) 1968-04-26
DE1589248A1 (de) 1970-04-30
ES340338A1 (es) 1968-06-01
SE304558B (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1968-09-30
FR1522814A (fr) 1968-04-26
BE698366A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1967-11-13
GB1193864A (en) 1970-06-03
DE1589248B2 (de) 1976-04-15
AT279735B (de) 1970-03-10
SE305031B (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1968-10-14
BE698451A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1967-11-13
CH490732A (de) 1970-05-15
CH464354A (de) 1968-10-31

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