Power circuit for a gas discharge lamp

A power circuit for at least one gas discharge lamp comprising a first filament and a second filament, the power circuit including an electronic driver circuit, for generating a first alternating voltage between the first and second filament for starting up the gas discharge lamp and for generating a second alternating voltage between the first and second filament for having the gas discharge lamp burn after it has been started up, wherein the power circuit further includes an electronic heating circuit for, at least during generation of the second alternating voltage, generating a first current through the first filament for heating the first filament and/or generating a second current through the second filament for heating the second filament;

• wherein the control circuit is configured for, when the magnitude of the lamp current is within a predetermined interval, increasing the magnitude of the first current and/or the magnitude of the second current if the current decreases and vice versa, while the magnitude of the first current and the magnitude of the second current becomes zero when the lamp current becomes greater than a predetermined value, while an upper limit of the interval is smaller than or equal to the predetermined value;
• wherein the control circuit is configured such that an upper limit of the interval becomes smaller when a dimming of the lamp increases and vice versa, while the upper limit is smaller than or equal to the predetermined value.

A power circuit for at least one gas discharge lamp comprising a first filament and a second filament, the power circuit including an electronic driver circuit, for generating a first alternating voltage between the first and second filament for starting up the gas discharge lamp and for generating a second alternating voltage between the first and second filament for having the gas discharge lamp burn after it has been started up, wherein the power circuit further includes an electronic heating circuit for, at least during generation of the second alternating voltage, generating a first current through the first filament for heating the first filament and/or generating a second current through the second filament for heating the second filament;

• wherein the power circuit includes control circuit for controlling the driver circuit and/or the heating circuit;
• wherein the control circuit is configured to carry out a first test wherein the driver circuit is activated while the heating circuit is deactivated and wherein a third alternating voltage generated by the control circuit is so low that in case of a broken or short-circuited lamp the driver circuit cannot get broken as a result of the broken or short-circuited lamp or wiring and wherein the control circuit is configured for carrying out the first test to measure the third voltage or a voltage related thereto and the lamp current or a current related thereto.

A power circuit for at least one gas discharge lamp comprising a first filament and a second filament, the power circuit including an electronic driver circuit, for generating a first alternating voltage between the first and second filament for starting up the gas discharge lamp and for generating a second alternating voltage between the first and second filament for having the gas discharge lamp burn after it has been started up, wherein the power circuit further includes an electronic heating circuit for, at least during generation of the second alternating voltage, generating a first current though the first filament for heating the first filament and/or generating a second current through the second filament for heating the second filament;

• wherein the power circuit includes a control circuit for controlling the driver circuit and/or the heating circuit;
• wherein the control circuit is configured to carry out a second test wherein the driver circuit is deactivated while the heating circuit is activated and wherein the generated first current and/or the generated second current are each so low that in case of a broken or short-circuited lamp or wiring the heating circuit cannot get broken as a result of the broken or short-circuited lamp or wiring and wherein the control circuit is configured for carrying out the second test to measure the first current or a current related thereto, the second current or a current related thereto, a voltage on output terminals of the heating circuit or a voltage related thereto.