EP0653903A2 - Méthode et appareil pour tube fluorescent - Google Patents

Méthode et appareil pour tube fluorescent Download PDF

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Publication number
EP0653903A2
EP0653903A2 EP94308013A EP94308013A EP0653903A2 EP 0653903 A2 EP0653903 A2 EP 0653903A2 EP 94308013 A EP94308013 A EP 94308013A EP 94308013 A EP94308013 A EP 94308013A EP 0653903 A2 EP0653903 A2 EP 0653903A2
Authority
EP
European Patent Office
Prior art keywords
tube
winding
assembly according
terminals
voltage
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Withdrawn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
EP94308013A
Other languages
German (de)
English (en)
Other versions
EP0653903A3 (fr
Inventor
Trevor Henry Williams
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.)
Meggitt UK Ltd
Original Assignee
Meggitt UK Ltd
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 Meggitt UK Ltd filed Critical Meggitt UK Ltd
Publication of EP0653903A2 publication Critical patent/EP0653903A2/fr
Publication of EP0653903A3 publication Critical patent/EP0653903A3/fr
Withdrawn legal-status Critical Current

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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
    • H05B41/14—Circuit arrangements
    • H05B41/36—Controlling
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/02—Details
    • H01J61/04—Electrodes; Screens; Shields
    • 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
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
    • H05B41/14—Circuit arrangements
    • H05B41/24—Circuit arrangements in which the lamp is fed by high frequency ac, or with separate oscillator frequency
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
    • H05B41/14—Circuit arrangements
    • H05B41/36—Controlling
    • H05B41/38—Controlling the intensity of light
    • H05B41/39—Controlling the intensity of light continuously
    • H05B41/392—Controlling the intensity of light continuously using semiconductor devices, e.g. thyristor
    • H05B41/3921—Controlling the intensity of light continuously using semiconductor devices, e.g. thyristor with possibility of light intensity variations
    • 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
    • H01J65/046—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 capacitive means around the vessel

Definitions

  • This invention relates to a cold cathode fluorescent tube assembly and a method of controlling a cold cathode fluorescent tube.
  • conventional fluorescent tubes normally exhibit a pop-on effect in terms of illumination levels when the tube first strikes following the application of sufficient voltage, and similarly exhibit a tendency to pop-off in terms of illumination level, when the supplied voltage is sufficiently reduced.
  • GB-A-1250376 describes a linear gas-discharge indicator for indicating the variation in a parameter. This makes use of a gas discharge tube having a pair of electrodes and a third electrode which extends alongside the tube and which is maintained negative with respect to the first electrode by a steady voltage of sufficient magnitude to start a glow discharge providing preionisation within the tube. A much lower second voltage difference is then applied between the third and second electrodes to cause a glow discharge along a portion of the second electrode. This is a relatively complex system requiring the use of three electrodes and the application of two different voltages and in practice would not generate sufficient light for illuminating other objects.
  • a cold cathode fluorescent tube assembly comprises a cold cathode fluorescent tube having first and second terminals; and a voltage source connected to the terminals to generate a voltage therebetween, wherein the first terminal extends along the tube and is arranged such that progressively increasing or decreasing the voltage applied to the terminals by the voltage source causes fluorescence to progressively increase or decrease respectively along the tube.
  • a method of controlling a cold cathode fluorescent tube having first and second terminals, the first terminal extending along the tube comprises progressively varying a voltage applied across the terminals to cause a corresponding progressive variation in fluorescence to occur along the tube.
  • the first terminal By providing a tube along which the first terminal extends, preferably for substantially its whole length, fluorescence progresses along the tube due to the effect of localised electrical discharge at points along the first terminal resulting from the voltage applied having to ionise gas in the tube over a reduced effective distance between the terminals. Therefore, the pop-on effect present in prior art fluorescent tubes is no longer present.
  • substantially whole we mean that the first terminal should terminate just short of the end of the tube. It could extend over a shorter distance (e.g. half the tube length) or over the entire tube length.
  • the tube's normal pop-on effect in terms of illumination levels when sufficient power is applied is replaced with a more gradual, smoother increase in illumination level, which initially illuminates the tube dimly toward one end, and spreads gradually and controllably along the tube's length with increasing brightness, as applied power is slowly increased.
  • the gradual reduction in applied power to the tube results in the tube's brightness level more smoothly and controllably reducing in intensity and gradually receding, back along the tubes length until fully extinguished.
  • the first terminal may take the form of a single wire running parallel to a centre axis of the tube which is electrically isolated from the second terminal, but preferably the first terminal comprises one of a twin spiral winding a running lace winding, a semi-spiral winding and a helical winding.
  • this comprises a plurality of substantially equally spaced turns, although the spacing may be increased towards a remote end of the winding. This maintains control linearity towards the end of the tube.
  • the helical winding is wound at between 3 and 9 turns per inch, most preferably at 6 turns per inch.
  • a cold cathode, glass envelope fluorescent tube 1 is shown in Figure 1 in which a pair of terminals 2,3 are mounted at opposite ends. A first one of the terminals 2 is extended by a winding 4 soldered to the first terminal 2 at one end and electrically insulated from the second terminal 3 at the other end.
  • the terminals 2,3 are connected to an AC voltage generator 7. The voltage delivered across the terminals can be varied progressively from 0V to 12V via a control voltage input 8 of the generator 7.
  • the winding 4 is generally constructed from a thin gauge wire e.g. tinned copper wire wrapped tightly around the tube 1 forming a uniform spiral winding at approximately 6 turns per inch.
  • the winding 4 is cut off approximately 1 ⁇ 4 inch from the second terminal 3 and secured against the tube's glass surface with transparent adhesive tape or other insulated method of bonding (not shown).
  • the simple spiral has the practical advantages that it is simple and quick to apply by hand.
  • dimly illuminated area B gradually blends the un-illuminated area "A” with the fully illuminated area “C", and its boundaries are not as precisely defined as Figures 2A-2D portray. However, the area of merge between areas “A” and “C” as shown in Figures 2A-2D is approximately to scale.
  • turns it is not essential for the turns to be equally spaced along the tube's length for the effect to work, but equally spaced turns enhance the smoothness of control in terms of the light output along the tube's length.
  • FIG 3 the graph shows the relationship between the applied power generators control voltage and the measured Lux output from the 90mm tube.
  • Figure 4 shows the Lux output magnified for clarity, using the same data). The graph compares the same tube 1 measured with the winding 4 applied (wired), and without the winding 4 applied (unwired).
  • the graph measurements were recorded starting with the control voltage set to 2.85 volts i.e. with the applied power in the fully off condition, and then plotted as the applied power to the tube was increased slowly to full, which occurred with a controlling input voltage applied at the control input 8 to the generator 7 at about 4.0 volts d.c.
  • the controlling input voltage can be varied between 0-5Vac.
  • the applied tube power was then slowly reduced back to zero, with the tube brightness again recorded at intervals, hence showing the resultant hysteresis curves, labelled "increase” and "decrease” (for both the wired and unwired tube conditions).
  • the light level may be controlled smoothly from full brightness at about 1,600 Lux down to 0 Lux.
  • the use of a winding 4 considerably enhances the brightness control of a cold cathode fluorescent tube particularly at lower light levels, and eliminates the rapid increase and decrease in light amplitudes normally observed as the tube reaches it's striking (pop-on) and turn-off voltages.
  • a straight rod shaped cold cathode fluorescent tube of 4mm diameter and 90mm length was used.
  • the maximum tube current was 4.0mA and the tube required 260Vac running voltage and 600Vac strike voltage.
  • the wire used for the winding 4 was 0.22mm2 (24 to 25 swg) tinned copper wire extracted from standard equipment type 7/0.2mm PVC coated wire with the insulation removed.
  • the illuminated tube area smoothly expands from the non-connected winding end 5 of the tube 1, towards the connected end 6 of the tube 1 as power is gradually increased until at full power the entire tube's length is illuminated.
  • the light emitted from the tube 1 recedes from the full length, starting at the connected end 6 and retreats back towards the non-connected winding end 5, until the length of illumination finally diminishes to zero as power turns fully off.
  • the illuminated length of the tube has a tendency to step in increments equal to the resultant gap between each winding turn, as power is slowly increased or decreased to the tube.
  • FIG. 5A depicts a CCF tube 1 with a twin spiral winding 10. This was wound with two separate wires 11,12 both electrically connected to the same tube end electrode 2 but insulated from each other. These two wires were wound spirally at approximately 6 turns per inch. One in a clockwise, the other in an anti-clockwise direction, both wires also being isolated electrically from the remaining CCF tube electrode 3.
  • the wire used was 0.22mm2 (24 to 25 swg) non-insulated tinned copper wire, hence both wires were in electrical contact with each other at each of the spiral cross-over points 13 occurring down the tubes length.
  • Figure 5B depicts a CCF tube with a "running lace” type winding 14, formed with 0.22mm2 (24 to 25 swg) non-insulated tinned copper wire electrically connected to one CCF tube electrode 2 and electrically isolated from the other remaining electrode 3.
  • FIG. 5C Another possible winding involves adding additional wires to form a mesh.
  • a semi-spiral winding 15 as shown in Figure 5C could be applied although this is less favoured due to the difficulties of attaching the wire to the tube glass surface.
  • This winding does not completely wrap around the tube in a continuous spiralling manner, but completes a 360 degree wrap and then returns to form a 360 degree wrap in the opposite direction, this process repeating at alternate turns along the length of the tube.
  • a conductive strip of tissue paper-thin conductive foil approximately 1/8th inch wide was attached to the tube's surface such that the strip lay flat along the tube's length.
  • the foil was electrically connected to one of the tube's electrodes but isolated electrically from the remaining electrode. This worked reasonably well but the results were not as good in terms of lighting control as those obtained with the spiral type of tube winding.
  • the spiral winding allows greater control by permitting adjustment of the turns ratio along the tube's body, to give increased linear control of the lights progression along the tube, with respect to applied power.
  • the conductive strip applied was nontransparent, and hence obscured some of the 4mm diameter tube's surface and reduced the total amount of visible light from the tube as a result, which is an undesirable feature.
  • transparent or non-transparent conductive paint in the same form i.e. various spherical windings, could be used, or a CCF tube could be dipped vertically into a transparent conductive paint to form a complete coat around the tube extending from and hence electrically connected to one tube electrode 2 but leaving the remaining tube electrode 3 isolated.
  • FIG. 6 An arrangement of back-lighting for a practical Liquid Crystal Information Display has been derived using wire-wound CCF tubes as described above to give enhanced lighting control.
  • the tube arrangement is shown in Figure 6. This comprises three tubes 16,17,18. Tubes 16 and 17 are driven from the same high voltage A.C. generator 19, as shown in Figure 7, whilst tube 18 is driven from a second entirely separate generator of identical design and build (not shown).
  • the tubes 16, 17 are connected to the generator 19 by a common low tension line 20 and separate high tension lines 21,22.
  • the two generators are employed to provide a degree of redundancy in the event of circuit failures which is desirable in some applications.
  • FIG 8 shows a liquid crystal display 23 in which the three tubes 16,17,18 as depicted in Figure 6 are placed between the rear of the LCD display 23 and a silvered reflector 24 such that light output 25 from the tubes is focused with minimum loss onto the display. Between the CCF tubes 16,17,18 and the LCD display 23 is a thin transparent light diffusor panel 26 to help defocus unwanted bright spots, and provide an even light intensity level falling over the entire display area.
  • the three tubes are placed in a triangular formation, also the spiral windings are positioned such that one winding of a tube is electrically connected to a tube electrode at each corner. Note that with increase of applied power the light spreads along the tube, from the isolated spiral end of the tube towards the tube end with the electrode 2 and the spiral winding 4 connected, as indicated by arrows 27 for each tube.
  • the power applied to both tubes 16,17 in the twin generator circuit is matched electronically within the twin generator circuit, such that tubes 16,17 are equally bright at all power settings.
  • the power applied to the third tube, 18 is matched by adjusting an output balance control in the single generator circuit. This balancing between the circuits simply applies an offset to one of the circuits 0 to 5 volt Tube power controls inputs 28, such that when both drive circuit's power controls are connected together and a common control voltage applied, the emitted light from each of the three tubes 16,17,18 is approximately equal over the entire control range from fully off (minimum brightness), to fully on (maximum brightness).
  • the brightness level Upon resumption of power after an interrupt, the brightness level will always return to same pre-interrupt brightness level, irrespective of whether it was at fully brightness or very dim.
  • CCF tube Many versions of CCF tube are available in numerous combinations of length, diameters, and electrical parameters to which the invention would be applied. The details given are for the specific examples described, however the invention is equally applicable to any other cold cathode fluorescent tubes of similar mechanical and electrical characteristics, including specially shaped "specials” such as a "U” or "W” shape etc.

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  • Vessels And Coating Films For Discharge Lamps (AREA)
EP94308013A 1993-11-15 1994-10-31 Méthode et appareil pour tube fluorescent. Withdrawn EP0653903A3 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB939323511A GB9323511D0 (en) 1993-11-15 1993-11-15 Fluorescent tube assembly
GB9323511 1993-11-15

Publications (2)

Publication Number Publication Date
EP0653903A2 true EP0653903A2 (fr) 1995-05-17
EP0653903A3 EP0653903A3 (fr) 1996-12-04

Family

ID=10745183

Family Applications (1)

Application Number Title Priority Date Filing Date
EP94308013A Withdrawn EP0653903A3 (fr) 1993-11-15 1994-10-31 Méthode et appareil pour tube fluorescent.

Country Status (2)

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EP (1) EP0653903A3 (fr)
GB (1) GB9323511D0 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0765109A2 (fr) * 1995-09-21 1997-03-26 Smiths Industries Public Limited Company Lampes et systèmes à décharge dans un gaz
GB2305540A (en) * 1995-09-21 1997-04-09 Smiths Industries Plc Discharge lamps
FR2745460A1 (fr) * 1996-02-28 1997-08-29 Vinel Paul Louis Procede et dispositifs d'alimentation de lampes a decharge en haute frequence par couplage resonant adapte
GB2334617A (en) * 1998-02-23 1999-08-25 Smiths Industries Plc Gas discharge lamps and systems
WO2004068532A2 (fr) * 2003-01-30 2004-08-12 Koninklijke Philips Electronics N.V. Lampe fluorescente

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2269835A1 (fr) * 1974-05-02 1975-11-28 Philips Nv
US4101807A (en) * 1976-03-22 1978-07-18 Xerox Corporation Method and apparatus for controlling the temperature of low pressure metal or metal halide lamps
EP0174415A1 (fr) * 1984-06-29 1986-03-19 Bressan, Alessandro Système d'alimentation en parallèle de lampes au néon, fluorescentes et similaires
DE8706562U1 (fr) * 1986-12-01 1987-12-23 Jaeger, Gerd, 8561 Reichenschwand, De
DE8816269U1 (fr) * 1988-11-02 1989-04-13 Hartel, Peter
US5030894A (en) * 1986-05-30 1991-07-09 Kabushiki Kaisha Toshiba Rare gas discharge lamp device

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2269835A1 (fr) * 1974-05-02 1975-11-28 Philips Nv
US4101807A (en) * 1976-03-22 1978-07-18 Xerox Corporation Method and apparatus for controlling the temperature of low pressure metal or metal halide lamps
EP0174415A1 (fr) * 1984-06-29 1986-03-19 Bressan, Alessandro Système d'alimentation en parallèle de lampes au néon, fluorescentes et similaires
US5030894A (en) * 1986-05-30 1991-07-09 Kabushiki Kaisha Toshiba Rare gas discharge lamp device
DE8706562U1 (fr) * 1986-12-01 1987-12-23 Jaeger, Gerd, 8561 Reichenschwand, De
DE8816269U1 (fr) * 1988-11-02 1989-04-13 Hartel, Peter

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0765109A2 (fr) * 1995-09-21 1997-03-26 Smiths Industries Public Limited Company Lampes et systèmes à décharge dans un gaz
GB2305540A (en) * 1995-09-21 1997-04-09 Smiths Industries Plc Discharge lamps
AU708655B2 (en) * 1995-09-21 1999-08-12 Ge Aviation Uk Gas discharge lamps and systems
US5747946A (en) * 1995-09-21 1998-05-05 Smiths Industries Public Limited Corporation Gas discharge lamps and systems
EP0765109A3 (fr) * 1995-09-21 1998-11-25 Smiths Industries Public Limited Company Lampes et systèmes à décharge dans un gaz
GB2305540B (en) * 1995-09-21 1999-02-17 Smiths Industries Plc Gas discharge lamps and systems
EP0899991A1 (fr) * 1996-02-28 1999-03-03 Paul Vinel Procédé et dispositif d'alimentation de lampes à décharge en haute fréquence par couplage résonant adapté
FR2745460A1 (fr) * 1996-02-28 1997-08-29 Vinel Paul Louis Procede et dispositifs d'alimentation de lampes a decharge en haute frequence par couplage resonant adapte
GB2334617A (en) * 1998-02-23 1999-08-25 Smiths Industries Plc Gas discharge lamps and systems
US6373185B1 (en) 1998-02-23 2002-04-16 Smiths Industries Public Limited Company Gas discharge lamps with glow mode electrodes
GB2334617B (en) * 1998-02-23 2002-06-26 Smiths Industries Plc Gas discharge lamps and systems
WO2004068532A2 (fr) * 2003-01-30 2004-08-12 Koninklijke Philips Electronics N.V. Lampe fluorescente
WO2004068532A3 (fr) * 2003-01-30 2004-09-16 Koninkl Philips Electronics Nv Lampe fluorescente

Also Published As

Publication number Publication date
EP0653903A3 (fr) 1996-12-04
GB9323511D0 (en) 1994-01-05

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