EP0403211A2 - Tube à arc pour lampe à décharge à haute pression - Google Patents

Tube à arc pour lampe à décharge à haute pression Download PDF

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Publication number
EP0403211A2
EP0403211A2 EP90306357A EP90306357A EP0403211A2 EP 0403211 A2 EP0403211 A2 EP 0403211A2 EP 90306357 A EP90306357 A EP 90306357A EP 90306357 A EP90306357 A EP 90306357A EP 0403211 A2 EP0403211 A2 EP 0403211A2
Authority
EP
European Patent Office
Prior art keywords
arc tube
discharge chamber
lamp
arc
outline
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Withdrawn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
EP90306357A
Other languages
German (de)
English (en)
Other versions
EP0403211A3 (fr
Inventor
Kevin Hick
Barry Preston
Bruce Haywood Sharpe Rambaldini
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.)
Thorn EMI PLC
Original Assignee
Thorn EMI PLC
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 Thorn EMI PLC filed Critical Thorn EMI PLC
Publication of EP0403211A2 publication Critical patent/EP0403211A2/fr
Publication of EP0403211A3 publication Critical patent/EP0403211A3/fr
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • 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

Definitions

  • the present invention relates to an arc tube for a high pressure discharge lamp.
  • the present invention relates to a high intensity metal halide discharge lamp.
  • Figures 1(a) and 1(b) are schematic representations of an arc tube for a known single ended low power metal halide lamp;
  • Figure 1(b) is a cross-sectional view of the arc tube of Figure 1(a).
  • the discharge chamber 4 of the arc tube is made as near spherical as possible, although ellipsoidal geometries are also acceptable.
  • a spherical geometry for the arc tube yields a near isothermal temperature profile for the operating lamp. This is a highly desirable feature since it ensures stability of lamp performance, particularly colour and light output, with lamp operating position. Such lamps are classified as 'universal burning' and are suitable for use in display lighting.
  • Arc tubes for this type of lamp are fabricated from silica tubing of 11 mm bore with a wall thickness of 1.25 mm. The tubes contain a mixture of mercury together with the iodides and bromides of tin, sodium and thallium. Argon is also present at a cold pressure of 24KPa to act as a starting gas. Each arc tube is pinch sealed into a quartz outer jacket with nitrogen gas in the space between the arc tube and outer jacket. The assembly so produced is mounted onto a bi-pin ceramic base.
  • an arc tube for a high pressure discharge lamp comprising a discharge chamber containing a fill and electrical conductors extending into the discharge chamber to form electrodes, the electrical conductors being sealed in the arc tube by a single pinch seal portion wherein, at the interface of the discharge chamber and the pinch seal portion, the discharge chamber has at least in part a non-concave outline.
  • arc tubes provided in accordance with the present invention have a significantly higher bursting strength than prior art lamps, as shown in Figure 1, in which, at the interface of the discharge chamber and the pinch seal portion, the discharge chamber has a concave outline.
  • the inventors believe this is due to changes made in the complex way in which the electrode structures interrupt the internal geometry of the discharge chamber as compared with prior art arc tubes. Accordingly, in making the invention, the inventors had needed to appreciate that despite the prior art, it might be worthwhile investigating the role of pinch seal geometry on ultimate bursting strength.
  • the non-concave outline is a rectilinear outline. Modification of the geometry of the discharge chamber to other than a spherical geometry had been expected to modify the lamp performance to an unacceptable extent, in particular, to increase the variation of lamp colour with operating position. The inventors were surprised to find that the performance of lamps provided in accordance with this preferred embodiment was acceptable for a universal burning lamp.
  • the preferred non-concave outline is a convex outline.
  • FIG. 2 shows a high pressure discharge lamp 10 provided in accordance with the present invention.
  • An arc tube 12 is located in a quartz outer jacket 14 by a pinch seal 16 (shown in part).
  • the space 18 between the outer jacket 14 and the arc tube 12 is filled with nitrogen gas.
  • the assembly so produced is mounted onto a bi-pin ceramic base 22.
  • the arc tube 12 is fabricated from silica tubing having a bore and a wall thickness dependant on the wattage of the lamp to be produced which may be from 20W to 2.5kW.
  • the bore is 11 mm and the wall thickness is 1.25 mm.
  • the arc tube 12 has a discharge chamber 24 in which is present a fill comprising a mixture of 25 mg mercury together with the iodides and bromides of tin, sodium and thallium.
  • Argon is also present at a cold pressure of 24KPa to act as a starting gas.
  • a pair of electrical conductors 26, 28 are sealed into one end of the arc tube 12 at a single pinch seal portion 30 to provide a pair of spaced apart electrodes 32, 34 extending into the discharge chamber 24.
  • the other end of each of the electrical conductors 26, 28 is joined to a strip of molybdenum foil 36, 38 in the pinch seal portion 30.
  • the strips of foil 36, 38 are in turn joined to a pair of electrical leads 40, 42, for connection to the pins of the ceramic base 22 via the pinch seal 16.
  • the shape of the discharge chamber 24 in the arc tube 12 is defined, inter alia, by the shape of the pinch seal portion 30.
  • the discharge chamber 24 is shown as having a rectilinear outline 44 at the interface of the discharge chamber 24 and the pinch seal portion 30.
  • the arc tube is accordingly hereinafter termed a 'rectilinear arc tube'.
  • the discharge chamber may have a convex outline at the interface of the discharge chamber and the pinch seal portion 30 - hereinafter termed a 'convex arc tube'.
  • the radius of curvature of the convex outline can be as low as 7.5 mm (for a 150W lamp) to infinity (ie 'rectilinear'). In convex 'arc tubes' used in the experiments described hereinafter, the radius of curvature of the convex outline was 22.0 mm.
  • Figures 3 and 4 are schematic representations, similar to Figure 1, of lamps provided in accordance with the present invention.
  • Figure 3a shows a rectilinear arc tube 46 corresponding to the arc tube of Figure 2.
  • Figure 4a shows a convex arc tube 48.
  • Figures 3b and 4b show cross-sections of the arc tubes of Figures 3a and 4a along respectively the lines III - III and IV-IV.
  • the prior art arc tube of Figure 1 will hereinafter be termed a 'concave arc tube'.
  • lamp performance also needs to be considered when determining arc tube geometry.
  • Relevant parameters were measured for a large number of arc tubes of each type. The results are shown in Tables 2 to 4; Table 2 for (prior art) concave arc tubes; Table 3 for rectilinear arc tubes; Table 4 for convex arc tubes.
  • lamps with convex arc tubes show double the shift in X colour co-ordinates and colour temperature as compared with lamps with concave or rectilinear arc tubes.
  • convex arc tubes can be used in lamps intended for use in a single orientation.
  • the internal pressure within the arc tube is primarily controlled by the amount of mercury dosed into the arc tube and so the gains in ultimate bursting strength illustrated by the specific embodiments described can be expected for any metal halide dose. Similar gains are also expected for lamps of ratings other than 150W.
  • the present invention is expected to be equally applicable to lamps utilising bare arc tubes and to arc tubes sealed into glass or quartz envelopes with or without a gas fill between the arc tube and outer jacket.

Landscapes

  • Vessels And Coating Films For Discharge Lamps (AREA)
EP19900306357 1989-06-15 1990-06-11 Tube à arc pour lampe à décharge à haute pression Withdrawn EP0403211A3 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB898913798A GB8913798D0 (en) 1989-06-15 1989-06-15 Arc tube for a high pressure discharge lamp
GB8913798 1989-06-15

Publications (2)

Publication Number Publication Date
EP0403211A2 true EP0403211A2 (fr) 1990-12-19
EP0403211A3 EP0403211A3 (fr) 1991-07-10

Family

ID=10658499

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19900306357 Withdrawn EP0403211A3 (fr) 1989-06-15 1990-06-11 Tube à arc pour lampe à décharge à haute pression

Country Status (3)

Country Link
EP (1) EP0403211A3 (fr)
JP (1) JPH0353445A (fr)
GB (1) GB8913798D0 (fr)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61240561A (ja) * 1985-04-18 1986-10-25 Toshiba Corp 小形高圧金属蒸気放電灯
EP0219861A2 (fr) * 1985-10-24 1987-04-29 Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH Méthode de fabrication d'une lampe à décharge à haute pression à halogénures de métal à pincement unique et une lampe fabriquée suivant cette méthode
EP0230051A1 (fr) * 1986-01-15 1987-07-29 Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH Lampe à décharge à haute pression et procédé pour sa fabrication

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61240561A (ja) * 1985-04-18 1986-10-25 Toshiba Corp 小形高圧金属蒸気放電灯
EP0219861A2 (fr) * 1985-10-24 1987-04-29 Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH Méthode de fabrication d'une lampe à décharge à haute pression à halogénures de métal à pincement unique et une lampe fabriquée suivant cette méthode
EP0230051A1 (fr) * 1986-01-15 1987-07-29 Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH Lampe à décharge à haute pression et procédé pour sa fabrication

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN, vol. 1, no. 88 (E-490)[2535], 18th March 1987; & JP-A-61 240 561 (TOSHIBA) 25-10-1986 *

Also Published As

Publication number Publication date
EP0403211A3 (fr) 1991-07-10
GB8913798D0 (en) 1989-08-02
JPH0353445A (ja) 1991-03-07

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