EP0011508B1 - A method for determining the values of components for a control circuit for a gas discharge lamp - Google Patents

A method for determining the values of components for a control circuit for a gas discharge lamp Download PDF

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Publication number
EP0011508B1
EP0011508B1 EP79302625A EP79302625A EP0011508B1 EP 0011508 B1 EP0011508 B1 EP 0011508B1 EP 79302625 A EP79302625 A EP 79302625A EP 79302625 A EP79302625 A EP 79302625A EP 0011508 B1 EP0011508 B1 EP 0011508B1
Authority
EP
European Patent Office
Prior art keywords
lamp
capacitor
values
control circuit
gas discharge
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.)
Expired
Application number
EP79302625A
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German (de)
English (en)
French (fr)
Other versions
EP0011508A1 (en
Inventor
Stephen Domville Mckie
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.)
PRACDES Pty Ltd
Original Assignee
PRACDES Pty 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 PRACDES Pty Ltd filed Critical PRACDES Pty Ltd
Priority to AT79302625T priority Critical patent/ATE8953T1/de
Publication of EP0011508A1 publication Critical patent/EP0011508A1/en
Application granted granted Critical
Publication of EP0011508B1 publication Critical patent/EP0011508B1/en
Expired 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
    • H05B41/02—Details
    • H05B41/04—Starting switches
    • H05B41/042—Starting switches using semiconductor devices

Definitions

  • the present invention relates to a method for determining the values of components for constructing a control circuit for a gas discharge lamp.
  • a former system that has been used is a series resistor operating in conjunction with a low-voltage striking tube.
  • the peak supply voltage is sufficient to strike the lamp.
  • the resistor has to drop 150v after lamp striking. This will dissipate approximately 20W at the lamp and 30W in the resistor, so that the arrangement is consuming approximately 50W for the 20W of illuminating power. This excessive power consumption is, of course, undesirable.
  • ballast circuit for a gas discharge lamp as presently adopted almost invariably has the form of the circuits disclosed in U.S. Patent Specifications Nos. 2 575 001 and 3 857 063.
  • the operating circuit for the lamp includes a series connection from the applied power through an inductor and a capacitor having a capacitance of about 13,uF and a reactance at the line frequency of about twice that of the inductor.
  • the principal function of the capacitor is to increase the starting potential on the lamp.
  • the operating circuit comprises only an inductor for stabilising the lamp operating current.
  • French Patent Specification No. 1 557 851 discloses a circuit for a gas discharge lamp in which the lamp is connected across input supply terminals, a series connection of an inductor and a capacitor being connected in series with the lamp between one of the input terminals and a terminal of the lamp.
  • a starting circuit comprising a series connection of a diode and a resistor is connected across the lamp. The inductor and the capacitor are provided to ensure correct operation of the lamp after starting, but no teaching is given as to what values they should have.
  • United States Patent Specification No. 3 983 449 discloses a ballast circuit for a gas discharge lamp, comprising a series connection of an indicator and a capacitor connected in series with the lamp between an input supply terminal and a terminal of the lamp.
  • a starter switch is connected across the lamp.
  • the reactance of the capacitor is between 24 and 55 times the reactance of the inductor, for the purpose of reducing third harmonic distortion.
  • this means that the impedance of the inductor is low, and barely sufficient to ensure adequate limitation of the peak current through the lamp.
  • a series capacitor of 30pF and a series choke of 2 to 3H function as the filter, with the values of both being kept as large as possible if normally undesirable variation in the light intensity from the lamp is to be avoided.
  • Swiss Patent Specification No. 492 379 which discloses a gas discharge lamp in which a ballast impedance and a protective case for elements of a starting circuit are housed inside the vessel of the lamp
  • French Patent Specification No. 963 793 which discloses a gas discharge lamp fitting in which opposite terminals of the lamp are connected to respective auxiliary electrodes spaced more than half-way down the length of the lamp from their connecting input terminals, the connection including resistors.
  • the object of the present invention is to provide for the use of a capacitor as a control element in a control circuit for a gas discharge lamp in series with an attenuator in the control circuit, in which the values of the capacitor and attenuator are optimised.
  • a method for determining the values of the capacitance of a capacitor and the impedance of an attenuator for a control circuit for a gas discharge lamp comprising input terminals for connection to an A.C.
  • the method comprising connecting a variable capacitor box and an attenuator box in one of respective ones of series circuits between each of said input terminals and a respective one of said output terminals and effectively in series with each other when said control circuit is operating and supplying the said input terminals with A.C., characterised in that a larger than anticipated capacitance value of said capacitor and impedance of said attenuator are introduced by said boxes, the capacitance value being then progressively reduced until light output from said lamp falls suddenly and then marginally increased, so as to restore the earlier light output, and said impedance is then progressively reduced until a readily discernible flicker in the light output occurs and then marginally increased so as to eliminate flicker in the light.
  • the present invention lies in the suitable selection of a capacitor, i.e. one with a capacitance barely sufficient to ensure adequate lamp operating power, together with an attenuator having an impedance barely sufficient to ensure adequate limiting of the peak current through the lamp.
  • This attenuator is required to have as low a value as practical otherwise the watts loss in this unit will approach that of a conventional inductive ballast. If the impedance value is too low, permitting excess peak current in operation, a fall in the light output and damage to the lamp will result. If the capacitor is of too low a value, there will be insufficient operating power delivered to the lamp. To have minimum losses, the capacitor reactance has to be as high as practical and the attenuator have as small an impedance as possible.
  • the circuit shown is designed for a low wattage fluorescent lamp and has its input terminals A and B connectable to a power supply S which in this case is 220/260 A.C. volts at 50Hz.
  • Output terminals C and D are connected to the filaments of a fluorescent lamp L and in series therewith is a capacitor C1 which, as will be explained hereafter, is chosen to determine the mean operating current supplied from the source S to the lamp L to ensure adequate lamp illumination, and is assigned a value commensurate with that task.
  • An attenuator in this instance a resistor R1 is also serially connected between the input terminals A-B and chosen to limit the operating current peaks supplied to the lamp L to protect it against damage, and is assigned a value according to this task.
  • the resistor R1 may be positioned in any part of the circuit providing it is in one of the series arms connecting the lamp L to the supply S. As shown in Figure 1, the resistor R is positioned between the output terminal D and the starting circuit. Although many different forms of ignition, or starting, circuits may be employed with the control circuit, such as an oscillating circuit, for the sake of circuit simplification a conventional series network of a diode D1 and resistor R2 is preferably used. The diode D1 supplies a charge to the capacitor C1 on each cycle of the supplied power. By appropriate selection of the resistance of resistor R2, the positive charge stored in capacitor C1 during the positive half cycles of the applied A.C.
  • resistor R2 may be in the range from 8,000 ohms to 30,000 ohms and will ensure such a voltate and additionally eliminate flicker from the lamp L, due to the shunt connection of diode D1, by effectively disconnecting the shunt circuit of network D1 and R2 when the lamp L fires. Upon firing, a damaging peak current would flow through the lamp L from capacitor C1 in the absence of the current limiter resistor R1.
  • the series attenuator may be composed entirely of an inductor X instead of resistor R1 or additionally thereto.
  • the watts loss, and physical size, of the inductor is considerably less than that of a conventional ballast inductor.
  • a typical capacitance for capacitor C1 for the operation of 4W, 6W, 8W and 13W conventional fluorescent lamps is 1 ; uF. Because the lamp characteristics are not identical for each of the above lamps, the value of the peak current limiting resistor R1 has to be varied and therefore the watts loss therein varies.
  • Typical values for the current limiter resistor R1 when associated with a 1.0 ⁇ F capacitor C1 for a 4W and 6W lamp are of the order of 300 ohms, 2 watts. For an 8W lamp, there values are approximately 500 ohms, 3 watts and in the case of a 13W lamp, 500 ohms, 5 watts.
  • the current limiting resistor R1 can be reduced and the watts loss therein is reduced because the average power through the lamp is reduced.
  • an 8W lamp would not have sufficient operating means current applied to it if an 0.8 ⁇ F capacitor was in series with the supply S. Therefore, a 1.0 ⁇ F capacitor having a reactance of approximately 3,200 ohms at 50 Hz would be used in series with a 300 ohms peak current limiter. Therefore, the peak current limiter R1 has a value about 10% of the value of the capacitor C1 reactance at 50 Hz.
  • capacitor C1 is typically a 4.0 ⁇ F capacitor which represents a reactance of about 800 ohms and this is used in association with an 80 ohms current limiting resistor R1, to produce a ratio of the capacitive reactance of capacitor C1 to the value of resistor R1 1 of about 10 to 1.
  • this ratio does not hold in all cases. If it were so, the following calculation would provide the optimum values:-Assume a supply of 250V at 50 Hz, a drop of 100V across the lamp after firing, a drop of 150V across a series resistor, 20W dissipated at the lamp, and 30W dissipated in the resistor.
  • capacitor C1 in miniature 15 mm diameter lamps (4W, 6W, 8W and 13W with varying lengths) as they all operate satisfactorily with a capacitor between 0.8,uF and 1.25,uF.
  • This is shown by the graphs of Figure 2, where capacitive values of 1.25 ⁇ F, 1.1 ⁇ F and 1 ⁇ F are plotted against values of resistor R1 and wattage loss in that resistor.
  • resistor R1 will be chosen to be within the area defined by the plotted co-ordinates for high wattage loss and light flicker. The specific part of this area chosen is preferably determined by the light output of the lamp.
  • the light plateau of an 8W lamp may be plotted on the same co-ordinates as the wattage on the graph of Figure 2. Therefore, by reference to Figure 2 it will be seen that the optimum values for an 8W lamp would be 1 JL F for capacitor C1 and 280 to 300 ohms, 2 watts for resistor R1.
  • a lamp and a control circuit according to the invention enable miniaturisation of components so that the components can be an integral part of a lamp, and also a considerable reduction in the cost of components.
  • Lamps controlled by such a circuit are preferably operated near the lower end of their light output plateau and although the illumination is reduced, but not to any marked extent, they, and especially lamps up to 20W rating, operate much more efficiently.
  • the watts loss per lumen output is better than that of a conventional ballast, particularly with the small reduction in light output referred to above.
  • the heat generated hy the control circuit is so low as to permit miniaturisation and lamp fittings do not require the contemporary large space for a ballast.
  • This invention permits the majority of the components, i.e. the capacitor and charging circuit, to be placed in the lamp base.
  • the components may be formed in an end cap of the lamp, or alternatively be a plug-in attachment, or if a lamp manufacturer desires he may incorporate the components actually in the glass envelope permitting the lamp merely to be plugged directly into the supply.
  • the resistor R1 is internally connected to the opposite end of the lamp, a lamp could have all its terminals at one end, the other end of the lamp merely having a glass dome, or being otherwise sealed off.
  • FIG 4 shows the actual size of a thermoplastic housing H and components C1, R2 and D1 housed therein which are used for fluorescent lamps of 4W, 6W, 8W and 13W rating whereby the housing H may be secured to the body of lamp fitting to serve as a protective cover for its housed components.
  • the connecting leads Y will be connected to terminals in the lamp fitting.
  • the resistor R1 will be connected externally of the housing H for better heat dissipation and will be in this instance 300 ohms, 2 watts.
  • Figure 3 shows the exciting arrangement comprising a piece of electrically conducting material 1 placed in contact with the outer glass envelope of the lamp L at a position approximately 80% of the way along the length of the lamp and electrically connected to the more remote lamp terminal socket D.
  • This arrangement may be duplicated by having a second contact 1A also positioned 80% of the way along the lamp L in relation to the other lamp terminal socket C and electrically connected thereto. That is to say, the contacts 1 and 1A are spaced more than half way down the length of the lamp from their connecting input terminals C and D.
  • the conducting contacts 1 and 1 A are accessible, that is not enclosed, it is necessary to meet local and/or International standards by inserting one or more resistors 2, in the connections between the contacts 1 and 1 A and the end terminals D and C.
  • This arrangement does not require an earth and its starting efficiency is such that full preheating of the lamp filaments is not necessary.
  • An alternative arrangement (not shown) is applicable where the base support or socket holder of the gas discharge lamp is earthed.
  • the alternative arrangement comprises a generally dome-shaped conducting rubber grommet, or the like, which is attached to the earthed metal lamp support with the top of the dome just touching the outer surface of the discharge lamp.
  • a conducting rubber contact approximately 20% of the way from each end of the lamp as there is a possibility that the supply voltage polarity may not be known. Both these arrangements are effective for use with those lamps that are known to be more difficult to strike, such as a 13 watt long lamp and a 40 watt, 12.2 metre lamp, and for prolonging the useful life of older lamps.

Landscapes

  • Circuit Arrangements For Discharge Lamps (AREA)
  • Manufacturing Of Printed Wiring (AREA)
  • Non-Metallic Protective Coatings For Printed Circuits (AREA)
  • Auxiliary Devices For And Details Of Packaging Control (AREA)
EP79302625A 1978-11-20 1979-11-19 A method for determining the values of components for a control circuit for a gas discharge lamp Expired EP0011508B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT79302625T ATE8953T1 (de) 1978-11-20 1979-11-19 Verfahren zur ermittlung von bauteilenwerten fuer eine steuerschaltung fuer eine gasentladungslampe.

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
AU6837/78 1978-11-20
AUPD683778 1978-11-20
AUPD953979 1979-07-11
AU9539/78 1979-07-11

Publications (2)

Publication Number Publication Date
EP0011508A1 EP0011508A1 (en) 1980-05-28
EP0011508B1 true EP0011508B1 (en) 1984-08-08

Family

ID=25642269

Family Applications (1)

Application Number Title Priority Date Filing Date
EP79302625A Expired EP0011508B1 (en) 1978-11-20 1979-11-19 A method for determining the values of components for a control circuit for a gas discharge lamp

Country Status (11)

Country Link
EP (1) EP0011508B1 (fi)
JP (1) JPS55105993A (fi)
DE (1) DE2967166D1 (fi)
FI (1) FI793608A (fi)
HU (1) HU182982B (fi)
IE (1) IE49213B1 (fi)
IN (1) IN153361B (fi)
NO (1) NO793708L (fi)
NZ (1) NZ192162A (fi)
PT (1) PT70469A (fi)
ZA (1) ZA796163B (fi)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2139022A (en) * 1983-04-26 1984-10-31 Gen Electric Ballast circuit for lamps with low voltage gas discharge tubes
US4626745A (en) * 1983-04-26 1986-12-02 General Electric Company Ballast circuit for lamps with low voltage gas discharge tubes
DE3603084A1 (de) * 1986-02-01 1987-08-06 Korte Licht Schaltung zum betrieb einer leuchtstofflampe
JP2693066B2 (ja) * 1991-11-07 1997-12-17 三洋電機株式会社 冷陰極放電管の放電始動装置
US5825139A (en) * 1995-11-02 1998-10-20 Hubbell Incorporated Lamp driven voltage transformation and ballasting system

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2297257A (en) * 1937-11-25 1942-09-29 Seitz Ernst Otto Alternating current discharge lamp

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR963793A (fi) * 1950-07-20
FR958142A (fi) * 1950-03-03
CH492378A (de) * 1966-02-01 1970-06-15 Gen Electric Elektrische Entladungslampe
FR1557851A (fi) * 1968-01-02 1969-02-21
DE2321063A1 (de) * 1973-04-26 1974-11-14 Walz Alfred Wechselstrombetriebsschaltung fuer gasentladungslampen, vorzugsweise mit konstantstrom-verhalten und zuendspannungserzeugung durch eine leistungsschwache gleichrichter-schaltung
GB1528910A (en) * 1974-12-11 1978-10-18 Thorn Electrical Ind Ltd Discharge lamp ballast circuits

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2297257A (en) * 1937-11-25 1942-09-29 Seitz Ernst Otto Alternating current discharge lamp

Also Published As

Publication number Publication date
IE49213B1 (en) 1985-08-21
NO793708L (no) 1980-05-21
DE2967166D1 (en) 1984-09-13
FI793608A (fi) 1980-05-21
NZ192162A (en) 1983-02-15
JPS55105993A (en) 1980-08-14
EP0011508A1 (en) 1980-05-28
ZA796163B (en) 1980-10-29
HU182982B (en) 1984-03-28
IN153361B (fi) 1984-07-07
PT70469A (en) 1979-12-01
IE792212L (en) 1980-05-20

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