US3912959A - High pressure sodium vapor discharge lamps - Google Patents

High pressure sodium vapor discharge lamps Download PDF

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Publication number
US3912959A
US3912959A US341849A US34184973A US3912959A US 3912959 A US3912959 A US 3912959A US 341849 A US341849 A US 341849A US 34184973 A US34184973 A US 34184973A US 3912959 A US3912959 A US 3912959A
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US
United States
Prior art keywords
envelope
sodium vapor
high pressure
discharge lamp
vapor discharge
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.)
Expired - Lifetime
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US341849A
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English (en)
Inventor
Akinori Muta
Yasuo Tsukuda
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Hitachi Ltd
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Hitachi Ltd
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Publication date
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    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/50—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on rare-earth compounds
    • C04B35/505—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on rare-earth compounds based on yttrium oxide
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/02—Details
    • H01J61/30—Vessels; Containers
    • H01J61/302—Vessels; Containers characterised by the material of the vessel

Definitions

  • the discharge lamp having this envelope excels in operation for a long period of time because the transparency of this envelope is not reduced at all when it is exposed to saturated sodium vapor at elevated temperatures.
  • This invention relates to high pressure sodium vapor discharge lamps generally and more particularly to' such lamps which use a ceramic envelope consisting of a sintered highly transparent polycyrstalline yttrium oxide.
  • a transparent polycrystalline alumina pipe was used as an envelope in a high pressure metal vapor discharge lamp.
  • This material has a total transmission of approximately 90 percent; and, when, used as an envelope in a high pressure sodium vapor discharge lamp, it has a radiation efficiency of approximately 100 lm/W, which is lower than that of a low pressure sodium vapor discharge lamp.
  • sodium is decreased gradually in its quantity, if the lamp is illuminated for a long time. Since the alumina of the envelope begins to evaporate and is changed into an oxide of lower valence as the temperature on the wall of the envelope exceeds l400C, the outer envelope is observed to blacken on its inner wall.
  • the transparent polycrystalline body produced by sintering a mixture of yttria (Y O and thoria (ThO produced and marketed by General Electric Company, U.S.A., under the trade name of Yttrolox shows excellent transmissivity, but it is blackened when the body is heated in a sodium vapor atmosphere.
  • An object of this invention is to obviate these drawbacks in high pressure sodium vapor discharge lamps and to provide a high pressure sodium vapor discharge lamp having a higher radiation efficiency and a lesser reduction in the quantity of sodium enclosed within the envelope, in addition to a reduction in blackening of the inner wall of the outer envelope and a longer service life.
  • the above object is attained by the use of a transparent polycrystalline yttria ceramic tube as an envelope in a high pressure sodium vapor discharge lamp.
  • the radiation efficiency can be increased to 116 to 124 Im/W, with suppression of' the decrease in sodium quantity within the envelope and the blackening of the inner wall of the outer envelope at higher than 1400C, while the service life of the discharge lamp can be prolonged.
  • FIG. 1 is a plan view of the high pressure sodium vapor discharge lamp according to this invention using a transparent polycrystalline yttria ceramic tube as an envelope;
  • FIG. 2 is a diagram showing the relation between the grain size and the in-line transmission of the yttria sintered body.
  • FIGS. 3 and 4 are detailed cross-sectional views of alternative embodiments of the high pressure sodium vapor discharge lamp in accordance with the present invention.
  • FIG. 1 shows, in plan view, a high pressure sodium v vapor discharge lamp according to the present invention, including a tubular elongated envelope 1 made of transparent yttria and sealed at both ends by niobium caps 4 and 5 with the use of a glass material consisting of, for example, 55 percent alumina, 39 percent calcia and 6 percent magnesia, said niobium caps carrying internal electrodes 2 and 3.
  • the envelope 1 is filled with an amalgam of 30 percent sodium sodium vapor and Xenon at a pressure of 20 mm Hg.
  • the envelope 1 is suspended in the conventional manner in an outer envelope 10 made of hard glass in which is provided electrical leads 6 and 7, connected in the known manner to a socket 8, as well as the standard getter rings 9. High vacuum pressure is maintained inside the outer envelope 10.
  • the transparent yttria envelope 1 is produced by the process comprising the steps of 1. Providing finely powdered yttrium oxide of high purity;
  • the purity of the powdered material can be varied, depending upon the usage of the powdered material or the property of the impurities mixed into the materialv For instance, in cases where the sintered body is used as an envelope, a window, or a lens in an optical system required to be heat resistant and have a high transparency, it is necessary to maintain the purity approximately higher than 99.99 percent and,-"above all, to avoid the mixture of terbium, molybdenum and other coloring impurities into the sinteredbody as much as possible.
  • the powdered material withgrain sizes less than 30p. may safely be employed, but a powdered material having grain sizes as small as possible, especially grain sizes in the range of 0.2 to 1.011.,IS preferred from the practical point of view.
  • a hydraulic press for instance, can be used for pressure molding the powdered material. While the molding pressure is not so critical, Sinterability tends to abruptly decrease with molding pressures less than 0.2 ton/cm Therefore, a molding pressure higher than 0.2 ton/cm is preferred. Sinterability can be increased by using a higher molding pressure, however, when the pressure is increased excessively, the density of the sintered body may be ocasionally lowered, due to the expansion of the pores of the sintered body occurring at the time of sintering.
  • the inner wall of the ing operation is preferably carried out for about on outer envelope l0 began to blacken as the temperature hour under a vacuum pressure of 10 mm Hg while 10 of the envelope exceeded 1400" C, but the envelope heating to 100 to 200 C.
  • a degasing operation is ening and could be safely used for a long time at a tempreferably carried out for more than 1 hour under a ture of 1400 C.
  • Table 2 shows the radiation efficiency of the high hig er than C- pressure sodium vapor discharge lamp using the above-
  • the heating atmosphere used in the sintering process mentioned transparent yttria envelope and that using is not strictly limited and may be Sele t d epending On the transparent alumina envelope. It is seen from this the type of heater used in the heating furnace.
  • Table that the discharge lamp made of transparent with the use of an x de r highelting m l h at yttria has a radiation efficiency of about 6 to 14 lm/W an oxygen atmosphere of a hydrogen or vacuum atmohigher than that of the comparative lamp. sphere may be used, respectively.
  • TABLE 2 dry hydrogen having a dew point approximately below 20 C may be preferably employed as an atmosphere Envelope Lighting Conditions Efficiency to introduce oxygen defects into the yttrium oxide L mp Lamp Total light Efficiency voltage current flux (lm) (lmlw) grams. It 18 to be noted that, when the heating is carried v (A) out under such an atmosphere for a long time, the sintered body is colored black partially or in its entirety.
  • the sintered body is subject Table Lshows the result ofsodium resistance tests on to cracks and a course grain boundary, although the the transparent yttria prepared by the above process, as data are not shown in FIG. 2. Therefore, the grain size well as transparent alumina prepared by the convenless than approximately 5 mm is usually preferred. tional process and commercially available Yttrolox.
  • both ends 11 of the envelope 1 shown in FIG. 1 is usually preferred to have the thickness of both ends 11 of the envelope 1 shown in FIG. 1 larger than that of the outer region thereof as seen in FIG. 3.
  • the outer surface of both ends of the envelope is preferably coated (see FIG. 4) with powdered heat-resistant material 12, such as alumina or yttria, so that the envelope may have a lower heat conductivity in the end portions than in the central zone.
  • powdered heat-resistant material 12 such as alumina or yttria
  • the powdered heat-resistant material such as alumina or yttria
  • oxides which have a thermal conductivity less than yttria and are chemically stable at operating temperatures.
  • a powdered heat-resistant material is preferably coated around outside of the opposite ends of the envelope up to the height of the electrodes.
  • a high pressure sodium vapor discharge lamp comprising:
  • tubular elongated envelope of sintered polycrystalline yttria consisting of corrosion resistant yttrium oxide and having an average grain size of 0.1 to 5 mm, said envelope having a pair of electrodes sealed into opposite ends, and
  • an ionizable medium including sodium vapor sealed within said envelope.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Vessels And Coating Films For Discharge Lamps (AREA)
US341849A 1972-03-16 1973-03-16 High pressure sodium vapor discharge lamps Expired - Lifetime US3912959A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2680772A JPS5710543B2 (enrdf_load_stackoverflow) 1972-03-16 1972-03-16

Publications (1)

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US3912959A true US3912959A (en) 1975-10-14

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US341849A Expired - Lifetime US3912959A (en) 1972-03-16 1973-03-16 High pressure sodium vapor discharge lamps

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US (1) US3912959A (enrdf_load_stackoverflow)
JP (1) JPS5710543B2 (enrdf_load_stackoverflow)
DE (1) DE2313253A1 (enrdf_load_stackoverflow)
NL (1) NL7303580A (enrdf_load_stackoverflow)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0041721A3 (en) * 1980-06-06 1982-09-15 Gte Products Corporation High pressure sodium lamp having improved efficacy
US5631522A (en) * 1995-05-09 1997-05-20 General Electric Company Low sodium permeability glass
US6136736A (en) * 1993-06-01 2000-10-24 General Electric Company Doped silica glass
US20120306340A1 (en) * 2010-02-15 2012-12-06 Osram Ag Lamp having gas filling

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL174683C (nl) * 1975-09-11 1984-07-16 Philips Nv Hogedrukgasontladingslamp.

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3363134A (en) * 1965-12-08 1968-01-09 Gen Electric Arc discharge lamp having polycrystalline ceramic arc tube

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3363134A (en) * 1965-12-08 1968-01-09 Gen Electric Arc discharge lamp having polycrystalline ceramic arc tube

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0041721A3 (en) * 1980-06-06 1982-09-15 Gte Products Corporation High pressure sodium lamp having improved efficacy
US6136736A (en) * 1993-06-01 2000-10-24 General Electric Company Doped silica glass
US5631522A (en) * 1995-05-09 1997-05-20 General Electric Company Low sodium permeability glass
US20120306340A1 (en) * 2010-02-15 2012-12-06 Osram Ag Lamp having gas filling
US8587186B2 (en) * 2010-02-15 2013-11-19 Osram Ag Lamp having gas filling

Also Published As

Publication number Publication date
JPS5710543B2 (enrdf_load_stackoverflow) 1982-02-26
DE2313253A1 (de) 1973-09-27
NL7303580A (enrdf_load_stackoverflow) 1973-09-18
JPS4895088A (enrdf_load_stackoverflow) 1973-12-06

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