EP0608205A1 - Compact fluorescent tube - Google Patents

Compact fluorescent tube Download PDF

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Publication number
EP0608205A1
EP0608205A1 EP94850009A EP94850009A EP0608205A1 EP 0608205 A1 EP0608205 A1 EP 0608205A1 EP 94850009 A EP94850009 A EP 94850009A EP 94850009 A EP94850009 A EP 94850009A EP 0608205 A1 EP0608205 A1 EP 0608205A1
Authority
EP
European Patent Office
Prior art keywords
tubular legs
tube
cross
bridging
corner regions
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Withdrawn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
EP94850009A
Other languages
German (de)
English (en)
French (fr)
Inventor
Torsten Axelsson
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.)
Auralight AB
Original Assignee
Lumalampan AB
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 Lumalampan AB filed Critical Lumalampan AB
Publication of EP0608205A1 publication Critical patent/EP0608205A1/en
Withdrawn legal-status Critical Current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
    • H01J61/33—Special shape of cross-section, e.g. for producing cool spot
    • 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
    • H01J61/32—Special longitudinal shape, e.g. for advertising purposes
    • H01J61/325—U-shaped lamps

Definitions

  • the present invention relates to a compact fluorescent tube, or lamp, which comprises one or more U-shaped main parts which together form a closed discharge chamber, electrodes mounted at each end of the discharge chamber, and an inner surface coating of fluorescent material, wherein each main part is formed by bending an originally straight glass tube and includes two straight and mutually parallel tubular legs of circular cross-sect ion and a bridging or connecting tube at one end of the tubular legs, and wherein the bridging tube forms at its junctions with the straight tubular legs corner regions whose cross-sectional areas are larger than the cross-sectional area of remaining parts of the bridging tube and the straight tubular legs.
  • the invention also relates to a method for producing such a compact fluorescent tube.
  • EP 61758 discloses one such known compact fluorescent tube in which the bridging tube in the tube U-bend is greatly enlarged in relation to the straight glass tubes, so as to enable the discharge column or stream to pass easily therethrough.
  • the pointed and outwardly extended corner regions of the bridging tube are formed in a manner to provide cooling zones in which the mercury vapour is cooled effectively as the tube burns, so that the mercury vapour is able to condensate and maintain a given partial pressure which is adapted to the best possible light yield.
  • This construction provides a compact fluorescent tube which functions well, although at the cost of a somewhat troublesome manufacturing process and also primarily at the cost of a fragile end product.
  • One object of the present invention is therefore to provide a compact fluorescent tube which has greater strength in manufacture, in transportation and in installation than the earlier known tubes of the aforementioned kind, while retaining or improving the operational properties of the tube.
  • Another object of the invention is to provide a harmonically and naturally curved compact fluorescent tube which will enable manufacture to be effected at a high rate of manufacture and at a cost which is lower than the cost of the earlier known tubes.
  • the invention is based on the realization that from a functional aspect, the top configuration of a compact fluorescent tube need not include pointed or outwardly drawn corner regions, outwardly projecting ridges, extreme constrictions or like features.
  • the marginal improvement of the starting and operational properties of such tubes that can be achieved with different special configurations is not in reasonable proportion to the additional costs caused by such special configurations.
  • the invention thus take the natural U-shape as its starting point, although the U-shape is adapted to create marked cooling zones in the tube corner regions and to avoid uneven glass distribution.
  • the corner regions have a larger cross-sectional area than remaining parts of the discharge chamber while the centre part of the bridging tube has a smaller cross-sectional area than said remaining parts of the discharge chamber while being curved slightly upwards from the corner regions, resulting in a harmonic and relatively easy to produce basic form.
  • the inner glass or mantle surface at the centre of the bend is conveniently enlarged and given a circular-arcuate shape, which together with the inner glass or mantle surfaces of the straight tubular legs define a keyhole-like space between the legs. This enables the glass to be distributed more evenly in the bend while avoiding the formation of puckers or folds, therewith reducing the risk of internal stresses and cracks.
  • the slightly upwardly curved bridging tube and the delimited sharp corner regions provide for gentle bending of the tube, which can therewith more readily be given a greater glass thickness in the outer periphery of the tube, i.e. a thickness of 0.35-0.5 mm, compared with a thickness of about 0.2 mm of the earlier tubes.
  • This together with the keyhole-shaped aperture in the centre of the bend also provides a small difference in glass thickness between the outer and the inner parts of the U-shaped tube. This enables the glass to be freed more readily from stresses in the process of manufacture, which in turn results in less risk of cracks forming in the glass.
  • the gentle and more natural curved form of the tube enables the top configuration of the tube to be produced at a lower blow-moulding pressure in order to fill-out all parts of the configuration, therewith enabling manufacture to proceed at a greater speed.
  • the mechanically strong U-form is much easier to handle during all parts of the tube manufacturing process, which is preferably fully automated.
  • the compact fluorescent tube 11 illustrated in Fig. 1 forms part of a so-called fluorescent tube lamp, which also includes a base housing 12 having a typical standardized screw base 13.
  • the base housing accommodates all the series impedence devices required to operate the lamp.
  • the compact fluorescent tube 11 may be fitted with a conventional compact fluorescent tube base which lacks such series impedence devices, in which case it is necessary to use lamp fittings which are intended particularly for such fluorescent tubes.
  • the illustrated compact fluorescent tube includes two U-shaped main parts 14 which are mutually joined by a connecting or bridging tube 15. Each main part has an electrode 16 mounted at one of the free ends 17 of the tube. Together with the bridging tube 15, the U-shaped main parts 14 form a continuous, air-tight discharge chamber with the electrode 16 mounted at each end.
  • Each main part 14 includes two straight tubular legs 19 of constant circular cross-section and a connecting or bridging tube 20 therebetween, this bridging tube having a slightly varying circular cross-section.
  • the main parts 14 are produced from originally straight tubes which have the same cross-section as the tubular legs 19.
  • the tubes are heat-treated and curved in a known manner about an inner bending centre 21, whereafter the U-shaped top is blow- moulded.
  • the originally straight tube is bent or curved through an angle of 180° around the bending centre 21, to a desired compact shape with a very small space e between the tubular legs 19.
  • the space between the inner proximal mantle surfaces 20 of the tubular legs, i.e. the distance e will preferably not be greater than 2-3 mm, thereby producing a very sharply curved inner wall surface 23 at the bending centre 21.
  • the inner glass surface 23 is given an arcuate shape whose diameter d is greater than the distance e between the tubular legs.
  • the diameter d will conveniently be 3-4 mm.
  • bridging tube 20 between the tubular legs 19 is shown in Figs. 3 and 4.
  • Marked or pronounced corner regions 24 are thus formed between the bridging tube and each tubular leg, whereas the major part of the bridging tube is comprised of a slightly arcuate top part 25.
  • the corner regions 24 have an extension f of 10°-20° of the total tube bend of 180°.
  • Each corner part 24 is suitably curved through an angle of between 30 and 45 of the bend angle and has a radius of curvature from the bending centre 21 of from 50-75% of the radius r of the straight tubular legs.
  • the slightly curved outer wall surface 26 of the top part 25 extends between the corner regions in a section of 80°-100° of the bend of the U-shaped main part and has a radius of curvature twhich is 3-8 times larger than the outer diameter of the straight tubular legs 19.
  • the values of the radii of curvature h and t are chosen to give the corner regions an outwardly projecting cold zone which is located slightly to one side of the main propagation path of the discharge column or stream, this propagation path being governed in this section of the tube by the cross-sectional area B of the top point or apex 27 centrally between the two corner regions 24.
  • the radius h will not be chosen at such a small value and the radius t will not be chosen at such a large value as to prevent a top form of desired strength and glass thickness being produced in a simple produc- tion/technical manner.
  • the flattened top part 25 creates together with the enlarged circular-arcuate wall surface 23 in the bending centre 21 a top form having an inner cross-sectional area A at the corner regions 24 which exceeds the cross-sectional area of remaining parts of the discharge chamber 28.
  • the smallest cross-sectional area B of the discharge chamber is formed at the same time in the apex 27 between the corner regions 24.
  • Sufficiently effective cooling zones can be created without requiring extreme variations in the cross-sectional area of the discharge chamber. Accordingly, the area A at the corner regions 24 will preferably be 10-20% greater than the corresponding inner cross-sectional area C of the straight tubular legs 19, and the cross-sectional area B at the apex 27 will preferably be 10-50% smaller than the cross-sectional area C.
  • each U-shaped main part will preferably have one and the same width across both legs and top region of the tube.
  • the outerdiam- eter k perpendicular to the plane of the U-bend in Fig. 3 will be constant along the entire bridging tube, whereas the perpendicular outer diameter m will vary along the bridging tube and will have a largest value ml immediately over a 30° bend and a smallest value m2 at the centre position or 90° bend.
  • the constant width k simplifies handling of the glass tubes in the blow-moulding process, while enabling gripping devices, etc., used in the automated manufacturing process to be adapted to one single external measurement.
  • the ratio between the diameters k and m also contributes towards a more uniform glass distribution over the section when bending and moulding the glass tube.
  • the thickness of the glass in the bridging tube will thus always be at least 0.35 mm and will not exceed 2 mm at the bending centre 21.

Landscapes

  • Vessels And Coating Films For Discharge Lamps (AREA)
EP94850009A 1993-01-20 1994-01-17 Compact fluorescent tube Withdrawn EP0608205A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE9300163A SE9300163L (sv) 1993-01-20 1993-01-20 Kompaktlysrör
SE9300163 1993-01-20

Publications (1)

Publication Number Publication Date
EP0608205A1 true EP0608205A1 (en) 1994-07-27

Family

ID=20388606

Family Applications (1)

Application Number Title Priority Date Filing Date
EP94850009A Withdrawn EP0608205A1 (en) 1993-01-20 1994-01-17 Compact fluorescent tube

Country Status (2)

Country Link
EP (1) EP0608205A1 (sv)
SE (1) SE9300163L (sv)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0851461A2 (en) * 1996-12-30 1998-07-01 General Electric Company Single-ended discharge lamp
EP1054434A2 (en) * 1999-05-19 2000-11-22 Matsushita Electronics Corporation U-shaped low pressure mercury vapor discharge lamp and manufacturing method thereof
EP1394837A2 (en) * 2002-08-27 2004-03-03 LCD Lighting, Inc. Serpentine fluorescent lamp with shaped corners providing uniform backlight illumination for displays

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61232550A (ja) * 1985-04-08 1986-10-16 Mitsubishi Electric Corp 低圧水銀蒸気放電ランプ
EP0373567A1 (en) * 1988-12-12 1990-06-20 Toshiba Lighting & Technology Corporation Low-pressure mercury vapor discharge lamp
US4977349A (en) * 1986-05-29 1990-12-11 Kabushiki Kaisha Toshiba Low-pressure mercury vapor discharge lamp
DE9207139U1 (sv) * 1992-05-26 1992-07-16 Patent-Treuhand-Gesellschaft Fuer Elektrische Gluehlampen Mbh, 8000 Muenchen, De

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61232550A (ja) * 1985-04-08 1986-10-16 Mitsubishi Electric Corp 低圧水銀蒸気放電ランプ
US4977349A (en) * 1986-05-29 1990-12-11 Kabushiki Kaisha Toshiba Low-pressure mercury vapor discharge lamp
EP0373567A1 (en) * 1988-12-12 1990-06-20 Toshiba Lighting & Technology Corporation Low-pressure mercury vapor discharge lamp
DE9207139U1 (sv) * 1992-05-26 1992-07-16 Patent-Treuhand-Gesellschaft Fuer Elektrische Gluehlampen Mbh, 8000 Muenchen, De

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 11, no. 77 (E - 487)<2524> 7 March 1987 (1987-03-07) *

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0851461A2 (en) * 1996-12-30 1998-07-01 General Electric Company Single-ended discharge lamp
EP0851461A3 (en) * 1996-12-30 1998-09-30 General Electric Company Single-ended discharge lamp
US5936341A (en) * 1996-12-30 1999-08-10 General Electric Company Single-ended discharge lamp
EP1054434A2 (en) * 1999-05-19 2000-11-22 Matsushita Electronics Corporation U-shaped low pressure mercury vapor discharge lamp and manufacturing method thereof
EP1054434A3 (en) * 1999-05-19 2003-07-16 Matsushita Electric Industrial Co., Ltd. U-shaped low pressure mercury vapor discharge lamp and manufacturing method thereof
EP1394837A2 (en) * 2002-08-27 2004-03-03 LCD Lighting, Inc. Serpentine fluorescent lamp with shaped corners providing uniform backlight illumination for displays
EP1394837A3 (en) * 2002-08-27 2006-08-16 LCD Lighting, Inc. Serpentine fluorescent lamp with shaped corners providing uniform backlight illumination for displays

Also Published As

Publication number Publication date
SE9300163D0 (sv) 1993-01-20
SE9300163L (sv) 1994-07-21

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