Fluorescent lamp controller

• US 5,111,115 A
• Filed: 01/08/1991
• Issued: 05/05/1992
• Est. Priority Date: 02/05/1990
• Status: Expired due to Fees

• Current Assignee: Electronic & Transformer Engineering Limited, Vusion International Limited
• Original Assignee: Electronic & Transformer Engineering Limited, Vusion International Limited
• Inventors: Ball, David P., Ensor, Donald R.
• Primary Examiner(s): LaRoche, Eugene R.
• Assistant Examiner(s): YOO, DO H
• Application Number:
  US07/638,528
• Time in Patent Office: 483 Days
• Field of Search: 315/101, 315/105, 315/205, 315/206, 315/207, 315/239, 315/DIG. 5, 315/DIG. 2
• US Class Current: 315/239
• CPC Class Codes: H05B 41/2325 provided with pre-heating electrodes
• CPC Class Codes: H05B 41/34 to provide a sequence of flashes
• CPC Class Codes: H05B 41/36 Controlling
• CPC Class Codes: H05B 41/42 in two steps only
• CPC Class Codes: Y10S 315/05 Starting and operating circuit for fluorescent lamp

Abstract

A circuit suitable for the instantaneous starting, continuation, and interruption of current through one or more gasfilled discharge tubes, in particular fluorescent lamps, is described. The circuit and lamp heaters are energized before instantaneous control can occur. One preferred silicon controlled rectifier (SCR) is used with a bridge rectifier. The SCR has the dual role of causing the capacitor to discharge through the pulse transformer, the secondary pulse voltage of which thereby causes the arc to strike immediately upon application of gate current, and then maintianing the lamp current as long as a supply of SCR gate current is provided. A second preferred control device, a TRIAC, is used without a bridge rectifier and again has a dual role of pulse-starting and maintaining current. This type of device is more conveniently arranged to provide for a dimming function as well. Applications include "flashing" advertising signs, general illumination, and signals.

Claims

1. Apparatus for providing from a source of alternating electric power the igniting and operating voltages for a gas discharge lamp, or lamps in series, said apparatus comprising:

a step-up transformer;

switching means;

charge storage means;

means for charging said charge storage means; and

switch control means to cause said switching means to be in either an "on" state or an "off" state;

said switching means and said charge storage means being connected in series with said step-up transformer to provide, when said switching means is closed, a series resonant circuit;

said step-up transformer being connected in series between the gas discharge lamp and the switching means;

said switching means being connected in series with said lamp or lamps whereby in use with said switching means and the gas discharge lamp connected to the source of alternating electric power, operation of the control means to switch "on" said switching means to cause it to conduct thereby allows said charge storage means to discharge transient current through said step-up transformer, causing an ignition pulse of high voltage to be created within said step-up transformer available to ignite said gas discharge lamp or lamps, and once ignited said lamp or lamps can continue to draw current from said power source via said step-up transformer and through said switching means, and operation of the switch control means in the "off" sense to act on said switching means will thereby switch "off" the lamp or lamps.

2. Apparatus as claimed in claim 1, wherein said switching means comprises a semiconductor device having a control line connected to said control means so that a signal applied to said control line can be used to switch said switching means "on" or "off".

3. A lighting circuit comprising a low pressure gas-discharge lamp, or a plurality of said lamps connected in series, the or each lamp having resistively heated cathodes, means for connecting said lamp or lamps to a source of alternating electric power, means for limiting the flow of current through the circuit and means for controlling and igniting said lamp or lamps, said controlling and igniting means comprising step-up transforming means having primary and secondary windings;

switching means;

charge storage means;

means for charging said charge storage means and switch control means to cause said switching means to be in either an "on" state or an "off" state;

said switching means and said charge storage means being connected in series with said primary winding to provide, when said switching means is closed, a series resonant circuit;

said secondary winding being connected in series between the gas discharge lamp and the switching means;

said switching means being connected in series with said lamp or lamps;

said switching means and the gas discharge lamp or lamps being connected in series with the source of alternating electric power, with a first power connection at a point between the switching means and the charge storage means, and a second power connection to a remote end of the lamp or series of lamps;

whereby in use, operation of the control means to switch "on" said switching means to cause it to conduct thereby allows said charge storage means to discharge transient current through said step-up transforming means, causing an ignition pulse of high voltage to be created within said step-up transforming means available to ignite said gas discharge lamp or lamps, and once ignited said lamp or lamps can continue to draw current from said power source via said step-up transforming means and through said switching means, and operation of the switch control means in the "off" sense to act on said switching means will thereby switch "off" the lamp or lamps.

4. A lighting circuit as claimed in claim 3, wherein said switch control means comprises means for repeatedly varying the conductivity of said switching means to cause said lamp or lamps to emit light in repeated flashes.

5. A lighting circuit as claimed in claim 4, wherein said switching means comprises a unidirectional silicon controlled rectifier or thyristor together with a bridge rectifier.

6. An illuminated display device comprising the lighting circuit as claimed in claim 3, and means for holding advertising or display material in proximity to said lamp or lamps.

7. The illuminated display device as claimed in claim 6, wherein said switch control means comprises means for repeatedly varying the conductivity of said switching means to cause said lamp or lamps to emit light in repeated flashes.

8. A lighting circuit comprising a low pressure gas-discharge lamp, or a plurality of said lamps connected in series, the or each lamp having resistively heated cathodes, means for connecting said lamp or lamps to a source of alternating electric power, and means for controlling said lamp or lamps;

said controlling means comprising step-up transforming means, first bidirectional switching means, charge storage means, means for charging said charge storage means, and switch control means to switch said first bidirectional switching means "on" or "off";

said first bidirectional switching means and said charge storage means being connected in series with said step-up transforming means to provide, when said first bidirectional switching means is closed, a series resonant circuit;

said step-up transforming means being connected in series between the gas discharge lamp and the first bidirectional switching means;

said switching means being connected in series with said lamp or lamps and said first bidirectional switching means and the gas discharge lamp or lamps being connected in series with the source of alternating electric power;

whereby in use, operation of the control means to switch "on" said first bidirectional switching means to cause it to conduct thereby allows said charge storage means to discharge transient current through said step-up transforming means, causing an ignition pulse of high voltage to be created within said step-up transforming means to ignite said gas discharge lamp or lamps, and once ignited said lamp or lamps can continue to draw current from said power source via said step-up transforming means and through said switching means, and operation of the switch control means to switch "off" said first bidirectional switching means will switch "off" or "dim" the lamp or lamps.

9. A lighting circuit comprising a low pressure gas-discharge lamp, or a plurality of said lamps connected in series, the or each lamp having resistively heated cathodes, means for connecting said lamp or lamps to a source of alternating electric power, and means for controlling said lamp or lamps;

said controlling means comprising step-up transforming means having primary and secondary windings, first bidirectional switching means, charge storage means, means for charging said charge storage means, and switch control means to switch said first bidirectional switching means "on" or "off";

said first bidirectional switching means and said charge storage means being connected in series with said step-up transforming means to provide, when said first bidirectional switching means is closed, a series resonant circuit;

said step-up transforming means being connected in series between the gas discharge lamp and the first bidirectional switching means;

said first bidirectional switching means and the gas discharge lamp or lamps being connected in series with the source of alternating electric power; and

at least one additional bidirectional switching means, connected in series with respective current limiting means, and connected in parallel with said first bidirectional switching means, said switch control means being adapted to switch "on" one or more of said bidirectional switching means to incrementally vary the amount of illumination emitted by said lamp or lamps;

whereby in use, operation of the switch control means to switch "on" said first bidirectional switching means to allow it to conduct thereby allows said charge storage means to discharge transient current through said step-up transforming means, causing an ignition pulse of high voltage to be created within said lamp or lamps, and once ignited said lamp or lamps can continue to draw current from said power source via said secondary winding, and operation of the switch control means to switch "on" or "off" said first or said additional bidirectional switching means will allow the brightness of the lamp to be controlled.

10. A lighting circuit as claimed in claim 9, wherein said first and said additional switching means each comprises a bidirectional thyristor or TRIAC.