US 6,788,006 B2 · Discharge lamp ballast with dimming

Abstract

A ballast includes a rectangular wave generating circuit that generates a rectangular wave signal; a driving signal generating circuit supplied with the rectangular wave signal and a dimmer signal of a PWM waveform of a frequency lower than that of the rectangular wave signal and outputting a driving signal of an output obtained by extracting the rectangular wave signal for a period corresponding to “on” period of the dimmer signal; a pulse transformer which is supplied with a rectangular wave voltage based on the driving signal, step up the rectangular wave voltage and applying it to a discharge lamp. A rectangular wave reset circuit is provided so as to reset the generation of the rectangular wave signal at a rising of the dimmer signal. The driving signal generating circuit extracts the rectangular wave signal for a period starting from when the dimmer signal is turned on, until a time at which the dimmer signal and the rectangular wave signal are both off.

Claims12

Dependent claims

A discharge lamp ballast comprising:

a rectangular wave generating circuit that generates a rectangular wave signal of a predetermined frequency;
a driving signal generating circuit into which the rectangular wave signal and a dimmer signal of a PWM waveform of a frequency lower than that of the rectangular wave signal are input, and which outputs, as a driving signal, a signal obtained by extracting the rectangular wave signal for a period corresponding to a period in which the dimmer signal is on;
and
a pulse transformer in which a rectangular wave voltage based on the driving signal is applied to a primary side, and the rectangular wave voltage is stepped up and applied to a discharge lamp;
wherein a rectangular wave reset circuit is provided so as to reset the operation of generating rectangular wave signal with the rectangular wave generating circuit at a rising of the dimmer signal, and
the driving signal generating circuit extracts the rectangular wave signal for a period starting from the dimmer signal is turned on, until a time at which the dimmer signal and the rectangular wave signal are both off.

3 more elements

A discharge lamp ballast comprising:

a rectangular wave generating circuit that generates a rectangular wave signal of a predetermined frequency;
a driving signal generating circuit into which the rectangular wave signal and a dimmer signal of PWM waveform of a frequency lower than that of the rectangular wave signal input, and which outputs, as a driving signal, an output obtained by extracting the rectangular wave signal for a period corresponding to a period which the dimmer signal is on;
and
a pulse transfer in which a rectangular wave AC voltage based on the driving signal is applied to a primary side, and the rectangular wave AC voltage is stepped up and applied a discharge lamp;
wherein an output reset circuit is provided so as to input a pulse voltage in phase with the rectangular wave AC voltage to the pulse transformer immediately after an end of the rectangular wave AC voltage in response to a completion of an ON period of the dimmer signal, a secondary side output of the pulse transformer being attenuated by application of the pulse voltage.

2 more elements

Dependencies are inferred from the claim text.

Discharge lamp ballast with dimming

Life of this patent

Discharge lamp ballast with dimming

Life of this patent

Abstract

Claims12