GB2179510A - A starting and dimming circuit for a fluorescent tube - Google Patents

A starting and dimming circuit for a fluorescent tube Download PDF

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Publication number
GB2179510A
GB2179510A GB08618131A GB8618131A GB2179510A GB 2179510 A GB2179510 A GB 2179510A GB 08618131 A GB08618131 A GB 08618131A GB 8618131 A GB8618131 A GB 8618131A GB 2179510 A GB2179510 A GB 2179510A
Authority
GB
United Kingdom
Prior art keywords
measuring resistor
fluorescent lamp
circuit
control circuit
direct
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.)
Granted
Application number
GB08618131A
Other versions
GB2179510B (en
GB8618131D0 (en
Inventor
Georg Hofmann
Wolfgang Kraft
Ernst Lengersdorf
Gottfried Stockinger
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.)
Diehl Verwaltungs Stiftung
Original Assignee
Diehl GmbH and Co
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 Diehl GmbH and Co filed Critical Diehl GmbH and Co
Publication of GB8618131D0 publication Critical patent/GB8618131D0/en
Publication of GB2179510A publication Critical patent/GB2179510A/en
Application granted granted Critical
Publication of GB2179510B publication Critical patent/GB2179510B/en
Expired legal-status Critical Current

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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
    • H05B41/36—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
    • H05B41/3927—Controlling the intensity of light continuously using semiconductor devices, e.g. thyristor with possibility of light intensity variations by pulse width modulation

Landscapes

  • Discharge-Lamp Control Circuits And Pulse- Feed Circuits (AREA)
  • Lighting Device Outwards From Vehicle And Optical Signal (AREA)

Abstract

A fluorescent tube 3 is energised from a direct voltage via a control circuit 2 connected in series with the fluorescent tube 3. The voltage drop across a current measuring resistor 4 controls the circuit 2, which in the no voltage state of the measuring resistor 4 generates high amplitude, short duration ignition voltage pulses. After ignition, the duty cycle of a switching transistor 5 is controlled by a circuit 7 having inputs from the measuring resistor 4 and from a brightness setting resistor 8. The polarity of the supply to the tube 3 may be reversed at intervals of a few minutes by an electronic circuit in order to compensate for the effects of ion migration arising when the tube is operated on unidirectional current. <IMAGE>

Description

SPECIFICATION A starting and dimming circuit for a fluorescent lamp The invention relates to circuit apparatus for controlling e.g. striking or starting and dimming, a fluorescent tube or other fluorescent lamp.
In aircraft, fluorescent tubes of the passenger compartment, which are connected to an alternating-voltage on-board mains, leads, on account of the alternating fields bound up therewith, to disturbances of other on-board circuits.
In order to obviate such disturbance possibilities, it has been proposed to feed the fluorescent tubes from a direct-voltage on-board mains. Then, however, difficulties occur upon the striking and dimming of the fluorescent tubes.
The task of the invention is to provide circuit apparatus to which a fluorescent tube can be connected to be started and dimmed in a simple manner using a direct current power supply.
In accordance with the invention, there is provided apparatus connectable to a fluorescent lamp so that in said apparatus a directcurrent control circuit and a measuring resistor are in series with the fluorescent lamp and are arranged so that the voltage drop across the measuring resistor controls the direct-current control circuit, which, in the no-voltage drop state of the measuring resistor, generates ignition voltage peaks; and wherein an adjustable member is connected to the direct-current control circuit for adjusting the power input to the fluorescent lamp.
If the circuit apparatus is switched on, then initially the fluorescent lamp is still not started.
Therefore, at the measuring resistor there is no voltage drop. The direct-current control circit generates thereupon a striking voltage peak, which starts the fluorescent lamp. A voltage then arises across the measuring resistor. Then the desired brightness of the fluorescent lamp can be adjusted by means of the adjusting member.
In development of the invention, the directcurrent control circuit has in series with the fluorescent lamp an inductance and in series with this an electronic switch, which is actuated by a control circuit which, as a function of voltages from the measuring resistor and the adjusting member, adjusts the keying (on to off) ratio of the switch. Through switching of this kind the result is achieved that for striking the fluorescent lamp only a little energy is necessary and in operation a high efficiency is achieved. Switching-network equipment having a high efficiency is described in "Halbleiter-Schaltungstechnik", U. Tietze, Ch.
Schenk, 5th Edition, 1980, Berlin, Heidelberg, New York: Springer, pages 390 et sequ.
Further advantageous developments of the invention will become apparent from the subclaims and from the following description of an exemplified embodiment shown in the accompanying diagrammatic drawing showing a circuit diagram of apparatus for striking and dimming a fluorescent tube for operation by a direct-current mains supply.
A direct-current control circuit 2 is connectable to a direct-voltage mains supply live U5 for an aircraft by an on switch 1. A fluorescent tube 3 is releasably connected in series between the direct-current control circuit 2 and a measuring resistor 4, one end of which is connected to an earth or return line, e.g. of negative polarity, of the direct-voltage means UB.
In the direct-current control circuit 2, the base-emitter section of a switching transistor 5 is connected in series with an output inductance 6 which provides an input to the fluorescent tube 3 in series therewith. The switching of the transistor 5 is timed by the control circuit 7, which works for example with a frequency of 20 kHz. The measuring resistor 4 and an adjusting member 8 formed by a potentiometer are connected to the control circuit 7 to determine the keying ratio of the control circuit 7 and thus the switching of the transistor 5. During the blocking phase of the switching transistor 5, a diode 9 connects a line, connecting the transistor to the inductance 6, to the negative pole of the direct voltage U5.
The mode of operation of the described circuit is for instance as follows: For starting the fluorescent tube 3 the onswitch 1 is closed. Initially fluorescent tube 3 is still not struck so that, no current flows through the measuring resistor 4 and the control circuit 7 also detects no voltage drop at the measuring resistor 4. Then the control circuit 7 sets at the switching transistor 5 a keying ratio which leads to a voltage pulse of high amplitude, but short duration, for example 10 us, to cause the fluorescent tube 3 to strike. When the tube 3 has started an appropriate current flows through the measuring resistor 4, and the corresponding voltage is detected by the control circuit 7 and causes the latter to control the keying ratio thereafter as a function of the voltage provided by the setting of the adjusting member 8. The adjusting member 8 permits adjustment of the current flowing through the fluorescent tube 3 and therewith the brightness of the fluorescent tube.
In order to compensate for the effects of the ion migration in the fluorescent tube 3, which effects arise upon unidirectional the direct-current feed, the fluorescent tube 3 can be pole-reversed repeatedly at intervals of a few minutes, e.g. by an electronic polarity reversing circuit.
In the case of several fluorescent tubes, for each fluorescent tube a direct-current control circuit 2 of its own and a measuring resistor 4 of its own may be provided, whilst the onswitch 1 and the adjusting member 8 can be common to all the fluorescent tubes.

Claims (5)

1. Circuit apparatus for striking or starting and dimming a fluorescent lamp, characterised in that connectable in series with the fluorescent lamp is a direct-current control circuit; in that connectable in series with the fluorescent lamp is a measuring resistor; in that the voltage drop across the measuring resistor is utilised to control the direct-current control circuit, which in the no voltage drop state of the measuring resistor is arranged to generate striking voltage pulses; and in that connected to the direct-current control circuit is an adjusting member for adjusting the nominal direct current for the fluorescent lamp.
2. Apparatus as claimed in Claim 1, characterised in that the direct-current control circuit has an inductance connectable in series with the fluorescent lamp, and has an electronic switch in series with the inductance, which electronic switch is actuated by a control circuit which adjusts the keying ratio of the electronic switch as a function of voltages at the measuring resistor and the adjusting member.
3. Apparatus as claimed in Claim 2, characterised in that the fluorescent lamp is releasably connectable between the inductance and the measuring resistor.
4. Circuit apparatus for controlling a fluorescent lamp substantially as hereinbefore described with reference to the accompanying drawing.
5. Lighting apparatus comprising at least one fluorescent lamp and circuit apparatus as claimed in any preceding claim.
GB8618131A 1985-08-10 1986-07-24 A starting and dimming circuit for a fluorescent lamp Expired GB2179510B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19853528838 DE3528838A1 (en) 1985-08-10 1985-08-10 IGNITION AND DIMMING CONTROL FOR A FLUORESCENT TUBE

Publications (3)

Publication Number Publication Date
GB8618131D0 GB8618131D0 (en) 1986-09-03
GB2179510A true GB2179510A (en) 1987-03-04
GB2179510B GB2179510B (en) 1989-08-09

Family

ID=6278286

Family Applications (1)

Application Number Title Priority Date Filing Date
GB8618131A Expired GB2179510B (en) 1985-08-10 1986-07-24 A starting and dimming circuit for a fluorescent lamp

Country Status (3)

Country Link
DE (1) DE3528838A1 (en)
FR (1) FR2586155B1 (en)
GB (1) GB2179510B (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2649277A1 (en) * 1989-06-30 1991-01-04 Thomson Csf METHOD AND DEVICE FOR LIGHT GRADING FOR FLUORESCENT LAMP OF REAR LIGHTING OF LIQUID CRYSTAL DISPLAY
WO1998048597A1 (en) * 1997-04-24 1998-10-29 Mannesmann Vdo Ag Circuitry for dimming a fluorescent lamp

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19531458A1 (en) * 1995-08-26 1997-02-27 Telefunken Microelectron Operation of fluorescent lamp

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1053236A (en) * 1900-01-01
GB1449079A (en) * 1973-11-19 1976-09-08 Lutron Electronics Co Discharge mercury vapour lamp dimming system
GB1477928A (en) * 1973-08-27 1977-06-29 Lutron Electronics Co Energising circuit for gas discharge lamps
GB1496129A (en) * 1974-01-02 1977-12-30 Gen Electric Solid state ballast for gaseous discharge lamps
GB1529824A (en) * 1975-10-24 1978-10-25 Gen Electric Ballast circuit for gaseous discharge lamps
GB2016222A (en) * 1978-02-07 1979-09-19 Cremer Soc Discharge lamp supply circuit
EP0066481A1 (en) * 1981-05-20 1982-12-08 Compagnie De Signaux Et D'entreprises Electriques Electronic supply apparatus for discharge lamps

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3265930A (en) * 1962-05-03 1966-08-09 Gen Electric Current level switching apparatus for operating electric discharge lamps
US3471747A (en) * 1967-02-02 1969-10-07 Gen Motors Corp Starting circuit and solid state running circuit for high pressure arc lamp
US3531684A (en) * 1968-12-31 1970-09-29 Gen Electric Discharge lamp circuit for control of light intensity
US3913002A (en) * 1974-01-02 1975-10-14 Gen Electric Power circuits for obtaining a high power factor electronically
US4132925A (en) * 1976-06-15 1979-01-02 Forest Electric Company Direct current ballasting and starting circuitry for gaseous discharge lamps

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1053236A (en) * 1900-01-01
GB1477928A (en) * 1973-08-27 1977-06-29 Lutron Electronics Co Energising circuit for gas discharge lamps
GB1449079A (en) * 1973-11-19 1976-09-08 Lutron Electronics Co Discharge mercury vapour lamp dimming system
GB1496129A (en) * 1974-01-02 1977-12-30 Gen Electric Solid state ballast for gaseous discharge lamps
GB1529824A (en) * 1975-10-24 1978-10-25 Gen Electric Ballast circuit for gaseous discharge lamps
GB2016222A (en) * 1978-02-07 1979-09-19 Cremer Soc Discharge lamp supply circuit
EP0066481A1 (en) * 1981-05-20 1982-12-08 Compagnie De Signaux Et D'entreprises Electriques Electronic supply apparatus for discharge lamps
US4412154A (en) * 1981-05-20 1983-10-25 Compagnie De Signaux Et D'entreprises Electriques Start up frequency adjustment in an electronic power device for a discharge lamp

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
NOTE: US 4412154 AND EP A1 0066481 ARE EQUIVALENT; *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2649277A1 (en) * 1989-06-30 1991-01-04 Thomson Csf METHOD AND DEVICE FOR LIGHT GRADING FOR FLUORESCENT LAMP OF REAR LIGHTING OF LIQUID CRYSTAL DISPLAY
US5105127A (en) * 1989-06-30 1992-04-14 Thomson-Csf Dimming method and device for fluorescent lamps used for backlighting of liquid crystal screens
WO1998048597A1 (en) * 1997-04-24 1998-10-29 Mannesmann Vdo Ag Circuitry for dimming a fluorescent lamp
US6351080B1 (en) 1997-04-24 2002-02-26 Mannesmann Vdo Ag Circuitry for dimming a fluorescent lamp

Also Published As

Publication number Publication date
GB2179510B (en) 1989-08-09
FR2586155A1 (en) 1987-02-13
DE3528838A1 (en) 1987-02-12
GB8618131D0 (en) 1986-09-03
FR2586155B1 (en) 1990-06-29

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PCNP Patent ceased through non-payment of renewal fee