WO2001026428A1 - Alimentation electrique pour lampe a decharge - Google Patents

Alimentation electrique pour lampe a decharge Download PDF

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Publication number
WO2001026428A1
WO2001026428A1 PCT/GB2000/003776 GB0003776W WO0126428A1 WO 2001026428 A1 WO2001026428 A1 WO 2001026428A1 GB 0003776 W GB0003776 W GB 0003776W WO 0126428 A1 WO0126428 A1 WO 0126428A1
Authority
WO
WIPO (PCT)
Prior art keywords
power supply
lamp
circuit
circuit arrangement
driving
Prior art date
Application number
PCT/GB2000/003776
Other languages
English (en)
Inventor
Colin Julian Seymour
Original Assignee
Central Research Laboratories Limited
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 Central Research Laboratories Limited filed Critical Central Research Laboratories Limited
Publication of WO2001026428A1 publication Critical patent/WO2001026428A1/fr

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Classifications

    • 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
    • H05B41/26—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc
    • H05B41/28—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters
    • H05B41/2806—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters with semiconductor devices and specially adapted for lamps without electrodes in the vessel, e.g. surface discharge lamps, electrodeless discharge lamps
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Definitions

  • the present invention relates to a power supply for driving a discharge lamp, for example an electrodeless discharge lamp.
  • a discharge lamp for example an electrodeless discharge lamp.
  • a known electrical power oscillator designed to drive inductively coupled lamps has previously been described in GB 2,322,019, and is essentially as shown in Figure 1. Although this circuit is very efficient, there are areas in which improvements are desired, mainly for cost and size reduction:
  • the circuit must be adjusted by C ad .
  • This component is relatively expensive compared to a fixed capacitor, invokes production costs, and is susceptible to drift, for example if contaminated by sealant. Eventually excessive ageing can occur shortening the lifetime of the circuit. It is desirable to eliminate the tuning capacitor or allow the use of a trimming resistor instead, which is less costly.
  • High frequency devices e.g. fast switching, low distributed gate resistance power FETs.
  • Circuit must accommodate the reactive component of the gate impedance at the driving frequency (this is far more important at higher frequencies of operation).
  • a suitable phase shift response must be provided in the oscillator's feedback loop.
  • the circuit must generate sufficiently large electric field to strike the plasma discharge, then maintain a sufficiently high (but controlled) current in the induction coil to maintain an inductive plasma discharge.
  • Figure 2 shows a circuit arrangement according to the present invention
  • Figure 3 shows a coupling coil suitable for use with the circuit of Figure 2.
  • the present invention is suitable for driving inductively coupled gas discharge lamps with air-cored coils, and due to the relatively low inductance and the frequency dependency of coupling between the magnetic field and plasma, the coils must be driven with frequencies of at least a few MHz.
  • a frequency of 9- 10 MHz has been found a good compromise between the coil-plasma response which improves with frequency, and the capability of present-day low cost transistors to supply power, which declines with frequency.
  • the circuit must handle the particular characteristics of inductively coupled discharge lamps, that is to say a resonant circuit must generate a high order of voltage multiplication (Q) to strike the gas discharge and must therefore be driven from a circuit which has a low source impedance throughout the full RF cycle, and not be damaged by the high voltages and currents present, and must also continue to supply drive power efficiently when the initial ⁇ ' mode shifts to 'H' mode (power transferred by magnetic field to effective circulating current in the plasma) which results in an increase in effective loss resistance in the lamp resonant circuit.
  • Q voltage multiplication
  • any oscillator assuming that a feedback loop can be identified and broken at some point in order to measure energy flow as flowing from an output node on one side of the break to an input node on the other side of the break, the phase shift through the whole network must be zero, (or n times 360 degrees where n is an integer), and the gain magnitude must be 1. These are the Barkhausen criteria. In practical circuits, the unity gain results from the amplitude of oscillation growing until non-linear compression causes the gain magnitude to fall to unity.
  • the circuit arrangement shown in Figure 2 is arranged with a feedback network connected to capacitive taps into the resonant lamp circuit to produce self-oscillation. C2 and C3 provide the capacitive taps; L2 and L3 provide additional phase shift, and Tl and VC1 provide a phase shift correction/ tuning circuit (without which, it has not been found possible to obtain proper oscillation with H mode light output).
  • Tl was wound on a Neosid GmbH FlOb ferrite core 10 o.d. x 5 i.d. x 2.5 mm part no. 05 1342 00; Tla is 3 turns of 0.5mm diameter enamelled wire, Tib is 22 turns of 0.25mm diameter enamelled wire.
  • This transformer has the effect of making VC1 appear as a much larger equivalent variable capacitance (lOOOpF) between the gates of the FETs, which would otherwise be impracticable. Note that the voltage across VC1 will also be magnified by a factor of 7.3 so a suitably rated part needs to be selected.
  • FIG. 3 shows the mechanical details for the output coupling coil for the circuit arrangement of Figure 2.
  • Lie consists of 12 turns of 0.4 mm diameter PTFE covered wire (e.g. BICC size 1/0.40 ref. BSG210), close-wound on a 28.6 mm diameter gas discharge lamp envelope using a former, for experimental use only, of 100 micron thick plastic film as commonly used for overhead projection.
  • Lla and Lib are each one turn (i.e. two turns close-wound centre-tapped) of the same wire positioned with a gap of between 5 and 6mm from the end of the main lamp coil.
  • I(V dd )ave l.lA, and operating frequency of 9.3 MHz.
  • Self-oscillating frequency is controlled by lamp tuned circuit and hence is more tolerant of drift in component values over time (compared with the sensitivity of the previous circuit to drift in the gate circuit tuning capacitor C ad ⁇ and related wound components L ad

Landscapes

  • Circuit Arrangements For Discharge Lamps (AREA)

Abstract

L'invention concerne un aménagement de circuit d'alimentation électrique pour lampe à décharge. Ledit aménagement de circuit comporte un réseau de rétroaction possédant un enroulement connecté à des dérivations capacitives dans le circuit de lampe résonnant de manière à produire, à l'utilisation, une oscillation interne spontanée. Le réseau de rétroaction, qui fournit la commande de grille des dispositifs de commutation, présente un déphasage réglable assuré par un condensateur variable connecté à un enroulement secondaire de transformateur. Le transformateur comporte un enroulement primaire connecté entre les grilles des dispositifs de commutation.
PCT/GB2000/003776 1999-10-05 2000-10-03 Alimentation electrique pour lampe a decharge WO2001026428A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9923405.6 1999-10-05
GBGB9923405.6A GB9923405D0 (en) 1999-10-05 1999-10-05 A high frquency power oscillator

Publications (1)

Publication Number Publication Date
WO2001026428A1 true WO2001026428A1 (fr) 2001-04-12

Family

ID=10862071

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB2000/003776 WO2001026428A1 (fr) 1999-10-05 2000-10-03 Alimentation electrique pour lampe a decharge

Country Status (2)

Country Link
GB (1) GB9923405D0 (fr)
WO (1) WO2001026428A1 (fr)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1993026140A1 (fr) * 1992-06-05 1993-12-23 Diablo Research Corporation Lampe a decharge sans electrode contenant un amplificateur en montage push-pull de classe e et une bobine a enroulement bifilaire
GB2305311A (en) * 1995-09-18 1997-04-02 Gen Electric Self oscillating drive circuit for an electrodeless discharge lamp
DE19650110A1 (de) * 1996-12-03 1998-06-04 Patent Treuhand Ges Fuer Elektrische Gluehlampen Mbh Betriebsschaltung für eine elektrodenlose Niederdruckentladungslampe
GB2322019A (en) * 1997-02-07 1998-08-12 Central Research Lab Ltd Gas discharge lamp drive circuit

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1993026140A1 (fr) * 1992-06-05 1993-12-23 Diablo Research Corporation Lampe a decharge sans electrode contenant un amplificateur en montage push-pull de classe e et une bobine a enroulement bifilaire
GB2305311A (en) * 1995-09-18 1997-04-02 Gen Electric Self oscillating drive circuit for an electrodeless discharge lamp
DE19650110A1 (de) * 1996-12-03 1998-06-04 Patent Treuhand Ges Fuer Elektrische Gluehlampen Mbh Betriebsschaltung für eine elektrodenlose Niederdruckentladungslampe
GB2322019A (en) * 1997-02-07 1998-08-12 Central Research Lab Ltd Gas discharge lamp drive circuit

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
MIYAZAKI H ET AL: "HIGH-FREQUENCY CLASS-D CONVERTER DRIVING WITH FEEDBACK CAPACITORS FOR ELECTRODELESS FLUORESCENT LAMPS", CONFERENCE RECORD OF THE IEEE INDUSTRY APPLICATIONS CONFERENCE. IAS ANNUAL MEETING,US,NEW YORK, NY: IEEE, 12 October 1998 (1998-10-12), pages 2032 - 2037, XP000804054, ISBN: 0-7803-4944-X *

Also Published As

Publication number Publication date
GB9923405D0 (en) 1999-12-08

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