Abstract A circuit is provided for operating a cold-cathode discharge lamp which includes first and second closed circuits which share in common a capacitor. The first closed circuit includes a power source and an inductive stabilizer in combination with the aforesaid capacitor and the second closed circuit includes an inductor and a bidirectional diode thyristor in combination with the capacitor. A second bidirectional diode thyristor is provided which constitutes with the second closed circuit a starting circuit for the discharge lamp. The second thyristor has a lower break-over voltage than the first thyristor. The second closed circuit is such that the capacitor is charged through the second said bidirectional diode thyristor to the instantaneous value of the power source and is discharged by the first said bidirectional diode thyristor through the inductor to produce a high voltage which is applied to the lamp to ignite the same.
A circuit for operating a cold-cathode discharge lamp, said circuit comprising a power source and a capacitor coupled in closed circuit relationship, said lamp being coupled across said power source; and an inductor, a further capacitor and a first bidirectional diode thyristor coupled with the first said capacitor in a second closed circuit relationship; and a second bidirectional diode thyristor coupled between said inductor and said lamp and power source, said second thyristor being included in the first said closed circuit, said second thyristor having a lower break-over voltage than said first thyristor; said first said capacitor being charged through said second bidirectional diode thyristor to the instantaneous value of the power source and discharged by the first said bidirectional diode thyristor through said inductor to produce a high voltage which is applied to said lamp to ignite the same.
Claim 2
Dependent Claim
140 words
A circuit for operating a cold-cathode discharge lamp, said circuit comprising a power source and a capacitor coupled in closed circuit relationship, said lamp being coupled across said power source; and an inductor, a further capacitor and a first bidirectional diode thyristor coupled with the first said capacitor in a second closed circuit relationship; and a second bidirectional diode thyristor coupled between said inductor and said lamp and power source, said second thyristor being included in the first said closed circuit, said second thyristor having a lower break-over voltage than said first thyristor; said first said capacitor being charged through said second bidirectional diode thyristor to the instantaneous value of the power source and discharged by the first said bidirectional diode thyristor through said inductor to produce a high voltage which is applied to said lamp to ignite the same.
Claim 3
Dependent Claim
27 words
A circuit as claimed in claim 1, wherein the inductor of said second closed circuit includes a coil and core of magnetic material of square hysteresis characteristics.
Claim 4
Dependent Claim
24 words
A circuit as claimed in claim 1, wherein said inductor is a non-linear saturable inductor which includes a coil and a core of ferrite.
Claim 5
Dependent Claim
26 words
A circuit as claimed in claim 1, including for each of the first said and further capacitors a parallel resistor for the discharging of said capacitors.
Claim 6
Dependent Claim
30 words
A circuit as claimed in claim 1 comprising a bandpass filter consisting essentially of an inductance and capacitance, said filter being connected between the first said capacitor and power source.
Claim 7
Dependent Claim
18 words
A circuit as claimed in claim 1 comprising a capacitor and a resistor connected across said second thyristor.