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EP0192290A1 - Electric lamp having a coloured lamp vessel - Google Patents

Electric lamp having a coloured lamp vessel Download PDF

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Publication number
EP0192290A1
EP0192290A1 EP86200141A EP86200141A EP0192290A1 EP 0192290 A1 EP0192290 A1 EP 0192290A1 EP 86200141 A EP86200141 A EP 86200141A EP 86200141 A EP86200141 A EP 86200141A EP 0192290 A1 EP0192290 A1 EP 0192290A1
Authority
EP
European Patent Office
Prior art keywords
lamp
powder layer
lamp vessel
vessel
powder
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.)
Granted
Application number
EP86200141A
Other languages
German (de)
French (fr)
Other versions
EP0192290B1 (en
Inventor
Christiaan Prozée
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.)
Koninklijke Philips NV
Original Assignee
Philips Gloeilampenfabrieken NV
Koninklijke Philips Electronics NV
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 Philips Gloeilampenfabrieken NV, Koninklijke Philips Electronics NV filed Critical Philips Gloeilampenfabrieken NV
Publication of EP0192290A1 publication Critical patent/EP0192290A1/en
Application granted granted Critical
Publication of EP0192290B1 publication Critical patent/EP0192290B1/en
Expired legal-status Critical Current

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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01KELECTRIC INCANDESCENT LAMPS
    • H01K1/00Details
    • H01K1/28Envelopes; Vessels
    • H01K1/32Envelopes; Vessels provided with coatings on the walls; Vessels or coatings thereon characterised by the material thereof
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01JELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00Gas-discharge or vapour-discharge lamps
    • H01J61/02Details
    • H01J61/38Devices for influencing the colour or wavelength of the light
    • H01J61/40Devices for influencing the colour or wavelength of the light by light filters; by coloured coatings in or on the envelope

Definitions

  • the invention relates to an electric lamp having a glass lamp vessel which is sealed in a gastight manner and in which a light source is arranged, which is connected to current supply conductors, which are passed through the wall of the lamp vessel to the outside, this lamp vessel having on its inner surface an electrostatically applied powder layer which comprises a light-scattering powder.
  • a lamp is known from European Patent Application 0116994 - (PHN 10.593).
  • An electrostatically applied powder layer is distinguished from a powder layer formed from a suspension.
  • the former kind of layer has a very low packing density, which may even be fifty times lower than that of a layer formed from a suspension having the same powder composition.
  • the surface of the layer has a remarkable roughness as compared with the smooth surface of a layer formed from a suspension, when applied to a transparent non-frosted lamp vessel, an electrostatically applied layer shows clearly, when looking at the lamp vessel along a tangent line to this lamp vessel, that the wall of the lamp vessel has certain thickness. This is not the case with a lamp vessel with a coating obtained from a suspension.
  • the method of coating a lamp vessel electrostatically affords the advantage that no organic solvents and binders are introduced into the lamp vessel, which have to be removed therefrom.
  • an electrostatically applied layer contains moisture, which is released gradually therefrom only during the operation of the lamp and adversely affects the quality of the lamp. The moisture may lead to the lamp vessel becoming leaky and in incandescent lamps may involve an accelerated transport of tungsten from the filament to the wall of the lamp vessel.
  • electrostatically applied layers containing a cadmium pigment exhibit a discolouring at areas at which they are strongly heated during the manufacture of the lamp. In a lamp in which the lamp vessel is fused at one end to a tube (stem tube) which tapers and projects into the lamp vessel, this discolouring occurs near this areas of the fusion of lamp vessel to stem tube.
  • the invention has for its object to provide a lamp of high quality coated electrostatically with powder.
  • this object is achieved in a lamp of the kind described in the opening paragraph in that the powder layer contains as an addition magnesium oxide.
  • magnesium oxide in a powder layer containing cadmium pigment reduces the discolouring of the layer.
  • 3 to 7 parts by weight thereof to 100 parts by weight of the other constituents of the powder With an addition of 3 to 7 parts by weight thereof to 100 parts by weight of the other constituents of the powder. the discolouring has been effectively suppressed. In general, the use of about 5 parts by weight per 100 parts by weight of the other constituents is sufficient to prevent the discolouring entirely or substantially entirely.
  • the light source of the lamp may be a filament, but may alternatively be a high-pressure discharge arc.
  • the powder layer comprises besides magnesium oxide at least one light--seattering substance. However, moreover a pigment may be present which may contain cadmium.
  • the quanity of magnesium oxide required for a maximum effect on the life of an incandescent lamp depends upon the moisture content of the electrostatic powder layer. In general, 3 to 10 parts by weight of magnesium oxide per 100 parts by weight of the other constituents of the powder are sufficient.
  • the powder layer will generally contain about 5 parts by weight of magnesium oxide per 100 parts by weight of the other constituents.
  • the lamp vessel 1 of bright glass sealed in a vacuum-tight manner has at its inner surface an electrostatically applied powder layer 2.
  • a filament 3 is arranged in the lamp vessel 1 and is connected to current supply conductors 4 which are passed through the wall of the lamp vessel to the outside and are connected to a lamp cap 5.
  • the lamp vessel 1 is fused at the end at which the lamp cap 5 is provided to a tube 6 (stem tube) which tapers and extends in the lamp vessel.
  • the fusion of the tube 6 to the lamp vessel 1 may lead to a discolouring of the powder layer in the proximity of the fusion area.
  • composition of the powder layer in the lamp according to the invention are (quantities in parts by weight):
  • the first layer can be much thinner than the layer according to Examples 1 and 2 and nevertheless the same colour satiration of the emitted light can be obtained.
  • the powder mixtures were obtained by mixing powders of the constituents in dry state. This has the advantage that no liquids are used and consumed so that environmental pollution and energy consumption for drying the mixture are avoided.
  • the lamps were manufactured in a flow of nitrogen. A positive pontential of 12 kV with respect to the powder mixture to be applied was given to the lamp vessel. The lamp vessel was fused to a stem tube provided with a gas filling or evacuated and then sealed. No or substantially no discolouring of the powder layer could be observed.
  • the Table indicates results of life tests carried out on 40 W, 230 V vacuum incandescent lamps of the kind shown in the drawing.
  • the Table also states whether a mixture of zirconium and aluminium as a water getter is present (+) or is not present (-) on a current supply wire in the lamp.
  • the lamps were operated in the bare state or in a hot fitting (a luminaire open only on the lower side) at 105% and 100%, respectively, of the nominal voltage (Vn).
  • the lamps 1 having a red electrostatically applied powder layer according to Example 1 have a considerably longer life than the lamps 3, whose powder layer does not contain magnesium oxide.
  • the presence of a mixture of zirconium and aluminium in lamps 2 does not exert an additional effect.
  • the lamps 4 provided with a white electrostatically applied powder layer according to Example 5 have a considerably longer life than the lamps 6 which do not contain MgO in the powder layer.
  • the mixture of zirconium and aluminium does not exert an additional effect either.

Landscapes

  • Vessels And Coating Films For Discharge Lamps (AREA)
  • Glass Compositions (AREA)

Abstract

An electric lamp having an electrostatically applied powder layer (2) on the wall of the lamp vessel (1) according to the invention contains MgO as an addition to this powder layer. The addition prevents discolouring of Cd-containing pigments in the powder layer and in the case of incandescent lamps results in lengthening of the life.

Description

  • The invention relates to an electric lamp having a glass lamp vessel which is sealed in a gastight manner and in which a light source is arranged, which is connected to current supply conductors, which are passed through the wall of the lamp vessel to the outside, this lamp vessel having on its inner surface an electrostatically applied powder layer which comprises a light-scattering powder. Such a lamp is known from European Patent Application 0116994 - (PHN 10.593).
  • An electrostatically applied powder layer is distinguished from a powder layer formed from a suspension. The former kind of layer has a very low packing density, which may even be fifty times lower than that of a layer formed from a suspension having the same powder composition. The surface of the layer has a remarkable roughness as compared with the smooth surface of a layer formed from a suspension, when applied to a transparent non-frosted lamp vessel, an electrostatically applied layer shows clearly, when looking at the lamp vessel along a tangent line to this lamp vessel, that the wall of the lamp vessel has certain thickness. This is not the case with a lamp vessel with a coating obtained from a suspension.
  • The method of coating a lamp vessel electrostatically affords the advantage that no organic solvents and binders are introduced into the lamp vessel, which have to be removed therefrom. However, it has been found to be disadvantageous that an electrostatically applied layer contains moisture, which is released gradually therefrom only during the operation of the lamp and adversely affects the quality of the lamp. The moisture may lead to the lamp vessel becoming leaky and in incandescent lamps may involve an accelerated transport of tungsten from the filament to the wall of the lamp vessel. It has further been found that electrostatically applied layers containing a cadmium pigment exhibit a discolouring at areas at which they are strongly heated during the manufacture of the lamp. In a lamp in which the lamp vessel is fused at one end to a tube (stem tube) which tapers and projects into the lamp vessel, this discolouring occurs near this areas of the fusion of lamp vessel to stem tube.
  • The invention has for its object to provide a lamp of high quality coated electrostatically with powder.
  • According to the invention, this object is achieved in a lamp of the kind described in the opening paragraph in that the powder layer contains as an addition magnesium oxide.
  • The presence of magnesium oxide in a powder layer containing cadmium pigment reduces the discolouring of the layer. With an addition of 3 to 7 parts by weight thereof to 100 parts by weight of the other constituents of the powder. the discolouring has been effectively suppressed. In general, the use of about 5 parts by weight per 100 parts by weight of the other constituents is sufficient to prevent the discolouring entirely or substantially entirely.
  • The light source of the lamp may be a filament, but may alternatively be a high-pressure discharge arc.
  • In incandescent lamps, the life was found to be considerably lengthened due to the presence of magnesium oxide as an addition in the powder layer. The powder layer comprises besides magnesium oxide at least one light--seattering substance. However, moreover a pigment may be present which may contain cadmium. The quanity of magnesium oxide required for a maximum effect on the life of an incandescent lamp depends upon the moisture content of the electrostatic powder layer. In general, 3 to 10 parts by weight of magnesium oxide per 100 parts by weight of the other constituents of the powder are sufficient. The powder layer will generally contain about 5 parts by weight of magnesium oxide per 100 parts by weight of the other constituents.
  • An embodiment of the lamp according to the invention is shown in the drawing in a side elevation partly broken away.
  • In the Figure, the lamp vessel 1 of bright glass sealed in a vacuum-tight manner has at its inner surface an electrostatically applied powder layer 2. A filament 3 is arranged in the lamp vessel 1 and is connected to current supply conductors 4 which are passed through the wall of the lamp vessel to the outside and are connected to a lamp cap 5. The lamp vessel 1 is fused at the end at which the lamp cap 5 is provided to a tube 6 (stem tube) which tapers and extends in the lamp vessel. With the use of cadmium--containing pigments in the powder layer 2, the fusion of the tube 6 to the lamp vessel 1 may lead to a discolouring of the powder layer in the proximity of the fusion area.
  • Examples of the composition of the powder layer in the lamp according to the invention are (quantities in parts by weight):
    Figure imgb0001
    Figure imgb0002
    Figure imgb0003
    Figure imgb0004
    Figure imgb0005
  • In the lamps according to Example 4, the first layer can be much thinner than the layer according to Examples 1 and 2 and nevertheless the same colour satiration of the emitted light can be obtained.
  • The powder mixtures were obtained by mixing powders of the constituents in dry state. This has the advantage that no liquids are used and consumed so that environmental pollution and energy consumption for drying the mixture are avoided.
  • The lamps were manufactured in a flow of nitrogen. A positive pontential of 12 kV with respect to the powder mixture to be applied was given to the lamp vessel. The lamp vessel was fused to a stem tube provided with a gas filling or evacuated and then sealed. No or substantially no discolouring of the powder layer could be observed.
  • The Table indicates results of life tests carried out on 40 W, 230 V vacuum incandescent lamps of the kind shown in the drawing. The Table also states whether a mixture of zirconium and aluminium as a water getter is present (+) or is not present (-) on a current supply wire in the lamp. The lamps were operated in the bare state or in a hot fitting (a luminaire open only on the lower side) at 105% and 100%, respectively, of the nominal voltage (Vn).
  • Table
    Figure imgb0006
  • It appears from the Table that the lamps 1 having a red electrostatically applied powder layer according to Example 1 have a considerably longer life than the lamps 3, whose powder layer does not contain magnesium oxide. The presence of a mixture of zirconium and aluminium in lamps 2 does not exert an additional effect.
  • It further appears that the lamps 4 provided with a white electrostatically applied powder layer according to Example 5 have a considerably longer life than the lamps 6 which do not contain MgO in the powder layer. In the lamps 5, the mixture of zirconium and aluminium does not exert an additional effect either.
  • In the lamps 1 and 2, no local discolouring of the powder layer containing cadmium pigment was observed, this in contrast with the lamps 3.

Claims (3)

1. An electric lamp having a glass lamp vessel which is sealed in a gas-tight manner and in which a light source is arranged, which is connected to current supply conductors which are passed through the wall of the lamp vessel to the outwide, this lamp vessel having at its inner surface an electrostatically applied powder layer which comprises a light-scattering powder, characterized in that the powder layer containes magnesium oxide as an addition.
2. An electric lamp as claimed in Claim 1, characterized in that the light source is an incandescent body.
3. An electric lamp as claimed in Claim 1 or 2, characterized in that the powder layer contains a cadmium compound as a pigment.
EP19860200141 1985-02-04 1986-02-03 Electric lamp having a coloured lamp vessel Expired EP0192290B1 (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
NL8500295 1985-02-04
NL8500295 1985-02-04
NL8503477A NL8503477A (en) 1985-02-04 1985-12-18 ELECTRIC LAMP WITH AN ELECTROSTATICALLY COVERED LAMP VESSEL.
NL8503477 1985-12-18

Publications (2)

Publication Number Publication Date
EP0192290A1 true EP0192290A1 (en) 1986-08-27
EP0192290B1 EP0192290B1 (en) 1989-05-24

Family

ID=26646015

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19860200141 Expired EP0192290B1 (en) 1985-02-04 1986-02-03 Electric lamp having a coloured lamp vessel

Country Status (6)

Country Link
EP (1) EP0192290B1 (en)
JP (1) JPS61183865A (en)
CN (1) CN1004954B (en)
DE (1) DE3663606D1 (en)
HU (1) HU192524B (en)
NL (1) NL8503477A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6919679B2 (en) * 2001-12-14 2005-07-19 Koninklijke Philips Electronics N.V. Contaminant getter on UV reflective base coat in fluorescent lamps
US7207250B2 (en) 2002-10-04 2007-04-24 Peter Lisec Process and device for moving and positioning sheets of glass

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0116994A1 (en) * 1983-02-10 1984-08-29 Koninklijke Philips Electronics N.V. Electric lamp having a coloured lamp envelope
EP0118962A1 (en) * 1983-03-14 1984-09-19 Koninklijke Philips Electronics N.V. Electric lamp having a coloured lamp envelope

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0116994A1 (en) * 1983-02-10 1984-08-29 Koninklijke Philips Electronics N.V. Electric lamp having a coloured lamp envelope
EP0118962A1 (en) * 1983-03-14 1984-09-19 Koninklijke Philips Electronics N.V. Electric lamp having a coloured lamp envelope

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6919679B2 (en) * 2001-12-14 2005-07-19 Koninklijke Philips Electronics N.V. Contaminant getter on UV reflective base coat in fluorescent lamps
US7207250B2 (en) 2002-10-04 2007-04-24 Peter Lisec Process and device for moving and positioning sheets of glass

Also Published As

Publication number Publication date
NL8503477A (en) 1986-09-01
JPS61183865A (en) 1986-08-16
HU192524B (en) 1987-06-29
DE3663606D1 (en) 1989-06-29
CN1004954B (en) 1989-08-02
EP0192290B1 (en) 1989-05-24
HUT39534A (en) 1986-09-29
CN86100621A (en) 1986-07-30

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