EP1130618A1 - Lampe fluorescente et procédé pour sa fabrication - Google Patents

Lampe fluorescente et procédé pour sa fabrication Download PDF

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Publication number
EP1130618A1
EP1130618A1 EP00830144A EP00830144A EP1130618A1 EP 1130618 A1 EP1130618 A1 EP 1130618A1 EP 00830144 A EP00830144 A EP 00830144A EP 00830144 A EP00830144 A EP 00830144A EP 1130618 A1 EP1130618 A1 EP 1130618A1
Authority
EP
European Patent Office
Prior art keywords
tubular element
capsule
end portion
lamp
diffusion
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Withdrawn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
EP00830144A
Other languages
German (de)
English (en)
Inventor
Elio Tito Bozzetti
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.)
Signal Lux Italia SpA
Original Assignee
Signal Lux Italia SpA
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 Signal Lux Italia SpA filed Critical Signal Lux Italia SpA
Priority to EP00830144A priority Critical patent/EP1130618A1/fr
Publication of EP1130618A1 publication Critical patent/EP1130618A1/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Withdrawn legal-status Critical Current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
    • H01J61/02—Details
    • H01J61/30—Vessels; Containers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
    • H01J9/24—Manufacture or joining of vessels, leading-in conductors or bases
    • H01J9/245—Manufacture or joining of vessels, leading-in conductors or bases specially adapted for gas discharge tubes or lamps
    • H01J9/247—Manufacture or joining of vessels, leading-in conductors or bases specially adapted for gas discharge tubes or lamps specially adapted for gas-discharge lamps
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/70—Lamps with low-pressure unconstricted discharge having a cold pressure < 400 Torr

Definitions

  • the present invention relates to a process for making lamps comprising the features set forth in the preamble of claim 1.
  • the present invention also pertains to a lamp to be obtained by the above process comprising the features set forth in the preamble of claim 10.
  • the invention particularly applies to production of fluorescent lamps.
  • florescent lamps are usually made up of a glass envelope containing inert gases, the inner surface of which is coated with a thin layer of phosphorescent substances and which is provided with a pair of electrodes for firing and maintaining the electrical discharge necessary to cause emission of visible radiations.
  • the type of gas contained within the envelope, the phosphorescent substances for glass coating and the amount of current circulating between the electrodes determine colour and intensity of the light emitted by the lamp.
  • small glass tubes of circular section are usually employed. These small tubes are first submitted to a powdering step consisting in dipping an end portion being processed into a mixture made up of phosphorus powders and appropriate glues. Phosphorus powders deposit on the dipped surfaces of the small tube which is then drawn out of the mixture and heated in a furnace at about 350°C. Under this situation solvent evaporation and fixing of the phosphorus layer to the small tube surfaces is achieved. Subsequently, a step of removing the layer of the phosphorescent substances in excess, i.e. the layer of phosphorescent substances deposited on the outer surface, on the end edge of the treated end portion and on a final annular portion of the inner surface of the small tube, is provided.
  • a pair of electrodes is fitted in the treated end portion of the small tube, and a positioning member usually consisting of a mandrel or similar template is subsequently introduced into the small tube through the opposite end with respect to the treated end portion until engagement of the pair of electrodes at respective seatings is accomplished. Once positioning steadiness of the electrodes in the small tube is ensured, the end edge of the treated end portion is heated to a temperature close to the melting temperature to cause closing of same.
  • the positioning member is drawn out of the small tube and a portion of said small tube is heated to the melting temperature (700°C - 900°C) so as to reduce the section thereof causing formation of a capillary duct defining a holding cavity in the treated end portion.
  • suction of the air present within the holding cavity and the small tube is carried out as well as subsequent filling of the same with an inert gas.
  • the capillary duct is heated again till causing occlusion and subsequent separation of same from the rest of the small tube structure.
  • the Applicant has found that the known process for making fluorescent lamps has some drawbacks affecting the production costs and impairing the quality of the obtained product.
  • each lamp is high because an important amount of phosphorescent substances is thrown away during the removal step.
  • a lamp in accordance with the present invention has been generally identified by reference numeral 1.
  • lamp 1 comprises a bulb 2 of transparent material and of substantially circular section having a base wall 3 from which a side wall 4 extends at right angles.
  • the side wall 4 On the opposite side from the base wall 3, the side wall 4 has a conical portion 5 terminating with a melting point 6.
  • the base wall 3, side wall 4, conical portion 5 and melting point 6 define a holding cavity 7 within which at least one inert gas is enclosed.
  • at least one pair of electrodes 8 is disposed, said electrodes being fixed relative to the bulb and having conductive elements 9 extending through the base wall 3 for connection with the ends of an electric circuit.
  • Lamp 1 further comprises at least one diffusion capsule 10 of transparent material engaged at the inside of bulb 2 and circumscribing electrodes 8 at least partly.
  • the body of the diffusion capsule 10 has a substantially bell-shaped conformation with an open end 11 defined by a substantially cylindrical portion 12 and a closed end 13 defined by a substantially frusto-conical portion 14 integral with the cylindrical portion 12.
  • the cylindrical portion 12 of the diffusion capsule 10 has an outer diameter substantially equal to the inner diameter of bulb 2 and consequently brings an outer surface 12a thereof into direct contact with an inner surface 2a of bulb 2.
  • the frusto-conical portion 14 seen in a diametrical section has a substantially curved profile defining a concave outer surface 14a.
  • This concave surface 14a advantageously defines a hollow space 15 between the frusto-conical portion 14 of the diffusion capsule 10 and the conical portion 5 of bulb 2.
  • the diffusion capsule 10 has at least one communication opening 16 which is preferably formed in a central region of the frusto-conical portion 14.
  • the diffusion capsule 10 is advantageously glued to bulb 2 by appropriate fixing substances to be preferably applied to at least one end edge 18 of the open end 11, at one or more gluing points 17. Said fixing substances can be applied along the whole extension of the end edge 18 so as to form a continuous rib.
  • a thin layer of phosphorescent substances (or phosphor) 19 is also applied to the diffusion capsule 10.
  • this phosphor layer 19 extends over the whole inner surface extension of the diffusion capsule 10.
  • FIGs. 2 to 9 Diagrammatically shown in Figs. 2 to 9 are the operating steps of a process for making the above described lamp. This process will be described in detail in the following of the present specification.
  • electrodes 8 are first introduced into a first end portion 20 of a tubular element 21 of circular section. Subsequently. a positioning member 22 is inserted into a second end portion 23 of the tubular element 21, opposite to the first end portion 20 (Fig. 3), to engage electrodes 8 in a preestablished position (Fig. 4). More specifically, the positioning member 22 that can consist for example of a mandrel or similar template, is inserted into the tubular element 21 until engagement of a pair of seatings 24 formed in one end 25 of the positioning member itself, with the corresponding pair of electrodes 8.
  • a heating step is provided for heating of the first end portion 20 of the tubular element 21 to a temperature close to the melting temperature (about 700°C-900°C) to cause occlusion of the first end portion itself.
  • the material forming the first end portion 20 that meanwhile has become malleable and easily deformable, is disposed in the configuration shown in Figs. 5 to 9, thereby forming the base wall 3 of lamp 1.
  • Heating and consequent closure of the first end portion 20 of the tubular element 21 further causes fastening of electrodes 8 with respect to the tubular element itself (Fig. 5), since the conductive elements 9 are incorporated into the base wall 3, at an intermediate region of their longitudinal extension.
  • the diffusion capsule 10 before being inserted into the tubular element 21, the diffusion capsule 10 is at least partly and preferably completely dipped into a mixture consisting of phosphorescent substances 19 suspended in appropriate solvents and fixing substances, so that the diffusion capsule 10 surfaces are completely coated with the above mentioned mixture. Then, the diffusion capsule 10 is heated, to a temperature of about 350°C for example, to ensure solvent evaporation and fixing of the phosphorescent substances 19.
  • a removal step is carried out for removing the phosphorescent substances 19 in excess deposited on the outer surface of the diffusion capsule 10. Removal of the phosphorescent substances is preferably executed by a tumbling process, in which a series of diffusion capsules 10 carrying the phosphorescent substances 19 are inserted into a rotating vessel. Under this situation, the diffusion capsules 10 are intimately mixed and the continuous mutual rubbing of their outer surfaces causes cleaning of same.
  • one or more gluing points 17 are applied to the end edge 18 of the open end 11.
  • Positioning of the diffusion capsule 10 within the tubular element 21 takes place by introducing said capsule through the second end portion 23 until the first end portion 20 is reached.
  • the fixing substances present on the end edge 18 ensure a rigid connection between the diffusion capsule 10 and the tubular element 21.
  • the diametrical shrinking of the tubular element 21 gives rise to formation of a communication duct 26 located at a position substantially spaced apart from, and intermediate between the end portions 20, 23. Formation of the communication duct 26 in addition defines the limits of the holding cavity 7 housing electrodes 8.
  • the air contained in the holding cavity 7 is sucked off through the communication duct 26 and the second end portion 23 of the tubular element 21. Then, at least one inert gas is admitted to the holding cavity 7 through the second end portion 23 and the communication duct 26.
  • a second heating step of the tubular element 21 is carried out to cause occlusion of the communication duct 26 and consequent separation of bulb 2 of lamp 1 from the remaining structure of the tubular element 21.
  • the present invention achieves the intended purposes.
  • the above described process for making fluorescent lamps ensures preservation of the phosphorescent substances 19 required for enabling the optimal operation of the produced lamp 1, in connection with efficiency and duration of same. More specifically, the presence of a diffusion capsule 10 carrying the phosphorescent substances 19 protects said substances from possible sintering with bulb 2 of lamp 1.
  • the diffusion capsule 10 protects the phosphorescent substances 19 against removal and scratching to which they are subject in the known art due to insertion and extraction of the positioning member 22.
  • insertion and extraction of the positioning member 22 take place before insertion of the diffusion capsules 10. In this manner any risk of damaging or reducing the amount of phosphorescent substances 19 is avoided even in the presence of lack of precision in centring the positioning member 22 with respect to the tubular element 21, because the positioning member 22 can only come into contact with the tubular element 21.
  • the process is speeded up and optimized in the steps of fixing the phosphorescent substances 19, removing the phosphorescent substances 19 from the outer surfaces of the diffusion capsules 10 and drying the solvents. In fact, these operations can be each carried out simultaneously on a great amount of diffusion capsules 10.

Landscapes

  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Vessels And Coating Films For Discharge Lamps (AREA)
EP00830144A 2000-02-29 2000-02-29 Lampe fluorescente et procédé pour sa fabrication Withdrawn EP1130618A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP00830144A EP1130618A1 (fr) 2000-02-29 2000-02-29 Lampe fluorescente et procédé pour sa fabrication

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP00830144A EP1130618A1 (fr) 2000-02-29 2000-02-29 Lampe fluorescente et procédé pour sa fabrication

Publications (1)

Publication Number Publication Date
EP1130618A1 true EP1130618A1 (fr) 2001-09-05

Family

ID=8175207

Family Applications (1)

Application Number Title Priority Date Filing Date
EP00830144A Withdrawn EP1130618A1 (fr) 2000-02-29 2000-02-29 Lampe fluorescente et procédé pour sa fabrication

Country Status (1)

Country Link
EP (1) EP1130618A1 (fr)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4754194A (en) * 1986-09-26 1988-06-28 Wilson Feliciano Flourescent light bulb
EP0369370A2 (fr) * 1988-11-15 1990-05-23 Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH Méthode de fabrication d'une enceinte de lampe
US5323087A (en) * 1992-11-20 1994-06-21 Gte Products Corporation Ultraviolet radiation starting source and lamp containing same
EP0782217A1 (fr) * 1995-12-13 1997-07-02 SIGNAL LUX S.p.A. Connecteur électrique basse tension, en particulier pour des signaux lumineux

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4754194A (en) * 1986-09-26 1988-06-28 Wilson Feliciano Flourescent light bulb
EP0369370A2 (fr) * 1988-11-15 1990-05-23 Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH Méthode de fabrication d'une enceinte de lampe
US5323087A (en) * 1992-11-20 1994-06-21 Gte Products Corporation Ultraviolet radiation starting source and lamp containing same
EP0782217A1 (fr) * 1995-12-13 1997-07-02 SIGNAL LUX S.p.A. Connecteur électrique basse tension, en particulier pour des signaux lumineux

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