US 7,459,867 B1Granted

Program start ballast

AssigneeOsram Sylvania Inc.

InventorsQinghong Yu, Kaiyu Wang

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Abstract

A ballast (10) for powering at least one gas discharge lamp (70) in a program start mode comprises an inverter (200), a resonant output circuit (400), and a control circuit (600). During operation of ballast (10), control circuit (600) monitors a voltage within resonant output circuit (400). When the monitored voltage reaches a first specified level that is indicative of sufficient filament preheating, control circuit (600) maintains the inverter operating frequency at a first present value for a preheating period so as to provide preheating of lamp filaments (72,74). Following completion of the preheating period, control circuit (600) allows the inverter operating frequency to decrease. When the monitored voltage reaches a second specified level that is indicative of sufficient ignition voltage, control circuit (600) maintains the inverter operating frequency at a second present value for an ignition period so as to provide ignition of lamp (70).

Claims24

Dependent claims

A ballast for powering at least one gas discharge lamp having a pair of lamp filaments, the ballast comprising:

an inverter having an inverter output terminal and being operable to provide, at the inverter output terminal, an inverter output voltage having an operating frequency;
a resonant output circuit coupled between the inverter output terminal and the lamp, and operable to provide:
(i) preheating of the lamp filaments;
(ii) an ignition voltage for igniting the lamp;
and (iii) a magnitude-limited current for operating the lamp;
a control circuit coupled to the output circuit and the inverter, wherein the control circuit is operable:
(a) to monitor a voltage within the resonant output circuit;
(b) in response to the monitored voltage reaching a first specified level, to control the inverter to maintain its operating frequency at a first present value for a predetermined preheating period so as to allow the resonant output circuit to provide preheating of the lamp filaments during the preheating period;
(c) upon completion of the preheating period, to allow the operating frequency of the inverter to decrease from the first present value;
and
(d) in response to the monitored voltage reaching a second specified level, to control the inverter to maintain its operating frequency at a second present value for a predetermined ignition period so as to allow the resonant output circuit to provide an ignition voltage for igniting the lamp.

8 more elements

A ballast for powering at least one gas discharge lamp having a pair of lamp filaments, the ballast comprising:

an inverter, comprising:
an input for receiving a source of substantially direct current (DC) voltage;
an inverter output terminal for providing an inverter output voltage having an operating frequency;
at least a first inverter switch;
and
an inverter driver circuit coupled to at least the first inverter switch and operable to commutate the first inverter switch at the operating frequency, the inverter driver circuit comprising:
a DC supply input for receiving operating power;
and
a voltage controlled oscillator (VCO) input, wherein the operating frequency is set in dependence upon a voltage provided to the VCO input;
a resonant output circuit coupled between the inverter output terminal and the lamp, and operable to provide:
(i) preheating of the lamp filaments;
(ii) an ignition voltage for igniting the lamp;
and (iii) a magnitude-limited current for operating the lamp;
a control circuit coupled to the output circuit and the inverter, wherein the control circuit comprises:
a voltage detection circuit coupled to the resonant output circuit, wherein the voltage detection circuit includes a detection output and is operable to provide:
(i) a first detection signal at the detection output in response to a monitored voltage within the resonant output circuit reaching a first specified level;
and (ii) a second detection signal at the detection output in response to the monitored voltage within the resonant output circuit reaching a second specified level;
a frequency-hold circuit coupled between the detection output of the voltage detection circuit and the VCO input of the inverter driver circuit, and operable:
(i) in response to the first detection signal, to substantially maintain the voltage provided to the VCO input at a first value for the duration of the predetermined preheating period;
and (ii) in response to the second detection signal, to substantially maintain the voltage provided to the VCO input at a second value for the duration of the predetermined ignition period;
and
a timing control circuit having at least a first output coupled to the frequency-hold circuit and operable to provide a preheat control signal at the first output upon completion of the preheating period.

19 more elements

A ballast for powering at least one gas discharge lamp having a pair of lamp filaments, the ballast comprising:

an inverter, comprising:
an input for receiving a source of substantially direct current (DC) voltage;
an inverter output terminal for providing an inverter output voltage having an operating frequency;
at least a first inverter switch;
and
an inverter driver circuit coupled to at least the first inverter switch and operable to commutate the first inverter switch at the operating frequency, the inverter driver circuit comprising:
a DC supply input for receiving operating power;
and
a voltage controlled oscillator (VCO) input, wherein the operating frequency is set in dependence upon a voltage provided to the VCO input;
a resonant output circuit, comprising:
first and second output connections adapted for coupling to a first filament of the lamp;
third and fourth output connections adapted for coupling to a second filament of the lamp;
a resonant inductor, comprising a primary winding, a first secondary winding, and a second secondary winding, wherein the primary winding is coupled between the inverter and the second output connection;
a resonant capacitor coupled to the second output connection;
a voltage-divider capacitor coupled between the resonant capacitor and circuit ground;
a direct current (DC) blocking capacitor coupled between the fourth output connection and circuit ground;
and
a first filament capacitor coupled in series with the first secondary winding of the resonant inductor, wherein the first filament capacitor and the first secondary winding are coupled in series between the first and second output connections;
and
a second filament capacitor coupled in series with the second secondary winding of the resonant inductor, wherein the second filament capacitor and the second secondary winding are coupled in series between the third and fourth output connections;
and
a control circuit, comprising:
a voltage detection circuit, comprising:
a detection output;
a first diode having an anode and a cathode;
a second diode having an anode and a cathode, wherein the anode of the first diode is coupled to the cathode of the second diode, and the anode of the second diode is operably coupled to circuit ground;
and
a low-pass filter comprising:
a filter resistor coupled between the cathode of the first diode and the detection output;
and
a filter capacitor coupled between the detection output and circuit ground;
a frequency-hold circuit, comprising:
a first electronic switch having a base, a collector, and an emitter, wherein the emitter is coupled to circuit ground;
a second electronic switch having a gate, a drain, and a source, wherein the drain is coupled to the base of the first electronic switch, and the source is coupled to circuit ground;
a third electronic switch having a base, a collector, and an emitter, wherein the collector of the third electronic switch is coupled to the collector of the first electronic switch, and the emitter of the third electronic switch is coupled to circuit ground;
a pull-down resistor coupled between the VCO input of the inverter driver circuit and the collector of the first electronic switch;
a first resistor coupled between the detection output of the voltage detection circuit and the base of the first electronic switch;
a second resistor coupled between the base of the first electronic switch and circuit ground;
a third resistor coupled between the detection output of the voltage detection circuit and the base of the third electronic switch;
and
a fourth resistor coupled between the base of the third electronic switch and circuit ground;
and
a timing control circuit, comprising at least a first output coupled to the second electronic switch of the frequency-hold circuit.

40 more elements

Dependencies are inferred from the claim text.

Facts

Application: 11/747,558Filed 11 May 2007
Published: US 2008/0278085 A113 Nov 2008
Granted: 2 Dec 2008
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

H05B 41/295
Using static converters: with semiconductor devices and specially adapted for lamps with preheating electrodes, e.g. for fluorescent lamps
Y10S 315/05
Electric lamp and discharge devices: systems: starting and operating circuit for fluorescent lamp
Y10S 315/07
Electric lamp and discharge devices: systems: starting and control circuits for gas discharge lamp using transistors
H05B
Electric heating