EP0645799A1 - Verwendung des Silbers zum Steuern des Iodniveaus in elektrodenlosen Entladungslampen hoher Intensität - Google Patents

Verwendung des Silbers zum Steuern des Iodniveaus in elektrodenlosen Entladungslampen hoher Intensität Download PDF

Info

Publication number
EP0645799A1
EP0645799A1 EP94306479A EP94306479A EP0645799A1 EP 0645799 A1 EP0645799 A1 EP 0645799A1 EP 94306479 A EP94306479 A EP 94306479A EP 94306479 A EP94306479 A EP 94306479A EP 0645799 A1 EP0645799 A1 EP 0645799A1
Authority
EP
European Patent Office
Prior art keywords
iodide
silver
fill
iodine
high intensity
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.)
Withdrawn
Application number
EP94306479A
Other languages
English (en)
French (fr)
Inventor
Hsueh-Rong Chang
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
General Electric Co
Original Assignee
General Electric Co
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by General Electric Co filed Critical General Electric Co
Publication of EP0645799A1 publication Critical patent/EP0645799A1/de
Withdrawn legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J65/00—Lamps without any electrode inside the vessel; Lamps with at least one main electrode outside the vessel
    • H01J65/04—Lamps in which a gas filling is excited to luminesce by an external electromagnetic field or by external corpuscular radiation, e.g. for indicating plasma display panels
    • H01J65/042—Lamps in which a gas filling is excited to luminesce by an external electromagnetic field or by external corpuscular radiation, e.g. for indicating plasma display panels by an external electromagnetic field
    • H01J65/048—Lamps in which a gas filling is excited to luminesce by an external electromagnetic field or by external corpuscular radiation, e.g. for indicating plasma display panels by an external electromagnetic field the field being produced by using an excitation coil
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/02—Details
    • H01J61/12—Selection of substances for gas fillings; Specified operating pressure or temperature
    • H01J61/125—Selection of substances for gas fillings; Specified operating pressure or temperature having an halogenide as principal component
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/02—Details
    • H01J61/24—Means for obtaining or maintaining the desired pressure within the vessel
    • H01J61/26—Means for absorbing or adsorbing gas, e.g. by gettering; Means for preventing blackening of the envelope
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/82—Lamps with high-pressure unconstricted discharge having a cold pressure > 400 Torr
    • H01J61/827—Metal halide arc lamps

Definitions

  • the present invention relates generally to high intensity metal halide discharge lamps and, more particularly, to the use of silver in metal halide discharge lamps for controlling the iodine level therein and thereby promoting arc stability and improving lamp performance.
  • high intensity metal halide lamps In operation of a high intensity metal halide discharge lamp, visible radiation is emitted by the metal portion of the metal halide fill at relatively high pressure upon excitation typically caused by passage of current therethrough.
  • One class of high intensity metal halide lamps comprises electrodeless lamps which generate an arc discharge by establishing a solenoidal electric field in the high-pressure gaseous lamp fill comprising the combination of one or more metal halides and an inert buffer gas.
  • the lamp fill, or discharge plasma is excited by radio frequency (RF) current in an excitation coil surrounding an arc tube which contains the fill.
  • RF radio frequency
  • the excitation coil acts as a primary coil, and the plasma functions as a single-turn secondary.
  • RF current in the excitation coil produces a time-varying magnetic field, in turn creating an electric field in the plasma which closes completely upon itself, i.e., a solenoidal electric field.
  • Current flows as a result of this electric field, producing a toroidal arc discharge in the arc tube.
  • Typical electrodeless metal halide discharge lamps use metal halides for generating white color lamp emission for general lighting applications.
  • free iodine formation and devitrification of the arc tube wall occur in electrodeless high intensity metal halide discharge lamps after exposure to the plasma arc discharge.
  • the amount of free iodine in the arc tube increases with time. This accumulating iodine, beyond a certain threshold, causes arc instability and eventual arc extinction.
  • an iodine getter for controlling the iodine level in electrodeless high intensity metal halide discharge lamps and thereby promote arc stability.
  • an iodine getter should extend the useful life of the lamp and hence not enhance devitrification and etching of the arc tube wall.
  • Silver is added to the fill of an electrodeless high intensity metal halide discharge lamp, which includes at least one metal iodide as a fill ingredient, for controlling the iodine vapor level therein.
  • silver reacts with free iodine, forming silver iodide (AgI), which has a relatively high boiling point and a relatively low vapor pressure.
  • the iodine level is thus controlled below an arc instability threshold to promote and maintain arc stability.
  • silver does not attack the quartz arc tube wall because silica (SiO2) is much more stable than silver oxide (Ag2O).
  • the addition of silver to the arc tube does not accelerate the decomposition of iodides in the fill, such as sodium iodide (NaI), cerium iodide (CeI3), lanthanum iodide (LaI3) and neodymium iodide (NdI3), which would otherwise enhance devitrification and etching of the quartz wall. Lamp performance and life are thus substantially improved using silver as an iodine getter.
  • iodides in the fill such as sodium iodide (NaI), cerium iodide (CeI3), lanthanum iodide (LaI3) and neodymium iodide (NdI3)
  • FIG. 1 illustrates a typical electrodeless high intensity metal halide discharge lamp 10.
  • lamp 10 includes an arc tube 14 formed of a high temperature glass, such as fused silica.
  • arc tube 14 is shown as having a substantially ellipsoid shape.
  • arc tubes of other shapes may be desirable, depending upon the application.
  • arc tube 14 may be spherical or may have the shape of a short cylinder, or "pillbox", having rounded edges, if desired.
  • Arc tube 14 contains a metal halide fill, including at least one metal iodide, in which a solenoidal arc discharge is excited during lamp operation.
  • a suitable fill comprises at least one rare earth metal halide (e.g., cerium iodide (CeI3), lanthanum iodide (LaI3), neodymium iodide (NdI3), praeseodymium iodide (PrI3)) and at least one alkali metal halide (e.g., sodium iodide (NaI), cesium iodide (CsI) and lithium iodide (LiI).
  • CeI3 cerium iodide
  • LaI3 lanthanum iodide
  • NdI3 neodymium iodide
  • PrI3 praeseodymium iodide
  • alkali metal halide e.g., sodium
  • One exemplary fill comprises sodium iodide, cerium iodide and xenon combined in weight proportions to generate visible radiation exhibiting high efficacy and good color rendering capability at white color temperatures.
  • a fill is described in commonly assigned U.S. Pat. No. 4,810,938 of P.D. Johnson, J.T. Dakin and J.M. Anderson, issued on Mar. 7, 1989 and incorporated by reference herein.
  • Another exemplary fill comprises a combination of lanthanum iodide, sodium iodide, cerium iodide, and xenon, as described in commonly assigned U.S. Pat. No. 4,972,120 of H.L. Witting, issued Nov. 20, 1990 and incorporated by reference herein.
  • a suitable excitation coil 16 may comprise, for example, a two-turn coil having a configuration such as that described in commonly assigned U.S. Pat. No. 5,039,903 of G.A. Farrall, issued Aug. 13, 1991 and incorporated by reference herein. Such a coil configuration results in very high efficiency and causes only minimal blockage of light from the lamp.
  • the overall shape of the excitation coil of the Farrall patent is generally that of a surface formed by rotating a bilaterally symmetrical trapezoid about a coil center line situated in the same plane as the trapezoid, but which line does not intersect the trapezoid.
  • suitable coil configurations may be used, such as that described in commonly assigned U.S. Pat. No. 4,812,702 of J.M. Anderson, issued Mar. 14, 1989 and incorporated by reference herein.
  • the Anderson patent describes a coil having six turns which are arranged to have a substantially V-shaped cross section on each side of a coil center line.
  • Still another suitable excitation coil may be of solenoidal shape, for example.
  • RF current in coil 16 results in a time-varying magnetic field which produces within arc tube 14 an electric field that completely closes upon itself.
  • Current flows through the fill within arc tube 14 as a result of this solenoidal electric field, producing a toroidal arc discharge 20 in arc tube 14.
  • the operation of an exemplary electrodeless high intensity discharge lamp is described in Johnson et al. U.S. Pat. No. 4,810,938, cited hereinabove.
  • silver is added to the metal iodide fill of an electrodeless high intensity discharge lamp in order to control the level of iodine vapor therein, thereby promoting arc stability.
  • silver reacts with free iodine that has been released due to metal loss in the arc tube wall, forming silver iodide (AgI).
  • the silver iodide Under lamp operating conditions, some of the silver iodide vaporizes and some remains in the liquid phase.
  • the vapor pressure of the silver iodide is determined by its liquid temperature which, in turn, is controlled by the power applied to the system.
  • the iodine that is bound to silver in the liquid phase is not released to the vapor phase because silver iodide has a relatively high boiling point (1506°C) and a relatively low vapor pressure.
  • the total iodine concentration in the vapor phase is regulated by the liquid temperature only, and an excessive iodine buildup is avoided.
  • arc stability is promoted and maintained.
  • the quantity of silver employed as an iodine getter according to the present invention in order to control iodine vapor pressure below an arc instability threshold is dependent upon such factors as type and quantity of fill ingredients, size and shape of the arc tube, excitation power and operating temperature.
  • An exemplary quantity is in the range, for example, from approximately 0.4 to 4 milligrams.
  • silver does not attack (or reduce) the quartz arc tube wall because silica (SiO2) is much more stable than silver oxide (Ag2O).
  • silver is less stable than the iodides of the lamp fill such as, for example, sodium iodide (NaI), cerium iodide (CeI3), lanthanum iodide (LaI3), neodymium iodide (NdI3), and praeseodymium iodide (PrI3), so that the addition of silver to the arc tube does not accelerate the decomposition of the iodides of the fill which would otherwise enhance devitrification and etching of the quartz wall. Lamp performance and life are thus substantially improved using silver as an iodine getter.
  • each group A and B of lamps were compared, each group consisting of lamps which did employ silver as an iodine getter and corresponding control lamps which did not employ an iodine getter.
  • the lamps of groups A and B are ellipsoid with dimensions 19mm x 26mm.
  • Each lamp of group A (and its corresponding control group) contained 8 mg of a fill mixture comprising sodium iodide (NaI) and neodymium iodide (NdI3) in a 5:1 molar ratio.
  • Each lamp of group B (and its corresponding control group) contained 10 mg of a fill mixture comprising sodium iodide (NaI) and neodymium iodide (NdI3) in a 7:1 molar ratio.
  • the lamps of group A were dosed with 1 mg of silver, and the lamps of group B were dosed with 0.49 mg of silver.
  • the lamps of group A were operated with excitation coils of 31 mm inner diameter (I.D.), and the lamps of group B were operated with excitation coils of 34 mm I.D., each group being tested at a power level of 300 coil Watts.
  • Each lamp of groups A and B had a quartz outer jacket filled with nitrogen gas surrounding the arc tube, the group A jackets having an outer diameter (O.D.) of 30 mm and the group B jackets having an O.D. of 33 mm.
  • Photometric data were taken for the lamps of group A at burn times of 100, 500, 1000 and 2000 hours.
  • the graph of Figure 2 compares the efficacy of the lamps of group A using silver as an iodine getter and the corresponding control lamps. Lamp efficacy was higher for the lamps of group A using silver as an iodine getter than for the control lamps. In addition, the lumen loss over the first 2000 hours of operation was much lower for the lamps of group A (2.5%) than for the control lamps (15%).
  • Free iodine formed in the arc tubes was measured by absorption spectroscopy at a wavelength of 515 nm.
  • the results for group A and B and their corresponding control groups are illustrated graphically in Figures 3 and 4, respectively.
  • Iodine accumulated rapidly in the ungettered control lamps.
  • the level of free iodine in the lamps using silver as an iodine getter was very low.
  • arc instability was observed in a lamp of control group B at 2642 hours at an iodine absorbance of 0.36, equivalent to 0.56 mg of I2 formed in the lamp.
  • the arc was stable and the iodine absorbance was near zero in a corresponding silver-gettered lamp.
  • Figure 5 shows color temperature as a function of lamp operating time for group A silver-gettered lamps and group A control lamps. The color temperature increased by 400°C in the control lamps at 2000 hours, while a constant color temperature was observed in the silver-gettered lamps.
  • Figure 6 compares the color rendition index (CRI) values measured for the silver-gettered and control lamps of group A.
  • CRI values measured at 100 hours were very similar in both the silver-gettered and control lamps.
  • lamp operation time increased, the CRI value of the control lamps increased, while the CRI of the silver-gettered lamps remained almost constant. Hence, color consistency is improved with the addition of silver to the fill.

Landscapes

  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Discharge Lamp (AREA)
  • Discharge Lamps And Accessories Thereof (AREA)
  • Common Detailed Techniques For Electron Tubes Or Discharge Tubes (AREA)
EP94306479A 1993-09-23 1994-09-02 Verwendung des Silbers zum Steuern des Iodniveaus in elektrodenlosen Entladungslampen hoher Intensität Withdrawn EP0645799A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US12538893A 1993-09-23 1993-09-23
US125388 1993-09-23

Publications (1)

Publication Number Publication Date
EP0645799A1 true EP0645799A1 (de) 1995-03-29

Family

ID=22419485

Family Applications (1)

Application Number Title Priority Date Filing Date
EP94306479A Withdrawn EP0645799A1 (de) 1993-09-23 1994-09-02 Verwendung des Silbers zum Steuern des Iodniveaus in elektrodenlosen Entladungslampen hoher Intensität

Country Status (3)

Country Link
EP (1) EP0645799A1 (de)
JP (1) JPH07153371A (de)
CA (1) CA2130424A1 (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19632220A1 (de) * 1995-08-11 1997-02-13 Matsushita Electric Works Ltd Elektrodenlose Entladungslampe
WO1998025294A1 (en) * 1996-12-04 1998-06-11 Koninklijke Philips Electronics N.V. Metal halide lamp

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2062956A (en) * 1979-11-13 1981-05-28 Gen Electric Metal halide lamp containing thorium
JPS5914246A (ja) * 1982-07-15 1984-01-25 Toshiba Corp メタルハライドランプ
US4810938A (en) * 1987-10-01 1989-03-07 General Electric Company High efficacy electrodeless high intensity discharge lamp
DE3838322A1 (de) * 1987-11-12 1989-05-24 Toshiba Kawasaki Kk Hochleistungs-entladungslampe
EP0397421A2 (de) * 1989-05-08 1990-11-14 General Electric Company Hochwirksame elektrodenlose Entladungslampe hoher Intensität
EP0453893A1 (de) * 1990-04-24 1991-10-30 Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH Hochdruckentladungslampe

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2062956A (en) * 1979-11-13 1981-05-28 Gen Electric Metal halide lamp containing thorium
JPS5914246A (ja) * 1982-07-15 1984-01-25 Toshiba Corp メタルハライドランプ
US4810938A (en) * 1987-10-01 1989-03-07 General Electric Company High efficacy electrodeless high intensity discharge lamp
DE3838322A1 (de) * 1987-11-12 1989-05-24 Toshiba Kawasaki Kk Hochleistungs-entladungslampe
EP0397421A2 (de) * 1989-05-08 1990-11-14 General Electric Company Hochwirksame elektrodenlose Entladungslampe hoher Intensität
EP0453893A1 (de) * 1990-04-24 1991-10-30 Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH Hochdruckentladungslampe

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 8, no. 95 (E - 242)<1532> 2 May 1984 (1984-05-02) *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19632220A1 (de) * 1995-08-11 1997-02-13 Matsushita Electric Works Ltd Elektrodenlose Entladungslampe
DE19632220B4 (de) * 1995-08-11 2005-07-28 Matsushita Electric Works, Ltd., Kadoma Elektrodenlose Entladungslampe
WO1998025294A1 (en) * 1996-12-04 1998-06-11 Koninklijke Philips Electronics N.V. Metal halide lamp
US5973453A (en) * 1996-12-04 1999-10-26 U.S. Philips Corporation Ceramic metal halide discharge lamp with NaI/CeI3 filling

Also Published As

Publication number Publication date
JPH07153371A (ja) 1995-06-16
CA2130424A1 (en) 1995-03-24

Similar Documents

Publication Publication Date Title
EP0399288B1 (de) Entladungslampe mit Verwendung von akustischen Resonanzschwingungen zur Sicherstellung eines hohen Wirkungsgrades
US4783615A (en) Electrodeless high pressure sodium iodide arc lamp
US4810938A (en) High efficacy electrodeless high intensity discharge lamp
US4972120A (en) High efficacy electrodeless high intensity discharge lamp
US5864210A (en) Electrodeless hid lamp and electrodeless hid lamp system using the same
US4890042A (en) High efficacy electrodeless high intensity discharge lamp exhibiting easy starting
US5479072A (en) Low mercury arc discharge lamp containing neodymium
US5013968A (en) Reprographic metal halide lamps having long life and maintenance
US5438235A (en) Electrostatic shield to reduce wall damage in an electrodeless high intensity discharge lamp
US5270615A (en) Multi-layer oxide coating for high intensity metal halide discharge lamps
US5965984A (en) Indium halide and rare earth metal halide lamp
US6501220B1 (en) Thallium free—metal halide lamp with magnesium and cerium halide filling for improved dimming properties
US5363015A (en) Low mercury arc discharge lamp containing praseodymium
EP0467610A2 (de) Schutzschicht aus Berylliumoxid für Entladungslampen hoher Intensität
EP0645799A1 (de) Verwendung des Silbers zum Steuern des Iodniveaus in elektrodenlosen Entladungslampen hoher Intensität
US5438244A (en) Use of silver and nickel silicide to control iodine level in electrodeless high intensity discharge lamps
US5343118A (en) Iodine getter for a high intensity metal halide discharge lamp
US5136214A (en) Use of silicon to extend useful life of metal halide discharge lamps
JP3241611B2 (ja) メタルハライドランプ
JP3269381B2 (ja) メタルハライドランプ
JPH04289654A (ja) メタルハライドランプ
JPH0864171A (ja) メタルハライドランプ
CA2000521A1 (en) High efficacy electrodeless high intensity discharge lamp exhibiting easy starting

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): DE FR GB IT

17P Request for examination filed

Effective date: 19950929

17Q First examination report despatched

Effective date: 19960209

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 19960620