Apparatus for lighting discharge lamps

Claim 2

Apparatus for lighting a discharge lamp having first and second filaments comprising: first coil means connected between one terminal of said first filament and one terminal of an AC source; means for interconnecting one terminal of said second filament and the other terminal of said AC source; a preheating circuit including at least one switching semiconductor element connected across the other terminals of said first and second filaments which passes a heating current from said AC source through said first and second filaments when said at least one switching element is conducting; and a pulse generating circuit generating a pulse voltage which is superposed upon the voltage of said AC source when said at least one switching element turns on said pulse generating circuit including: said at least one switching element in common with said preheating circuit; a capacitor coupled between said one terminal of said AC source and one terminal of said at least one switching element; and a second coil inductively cooperating with said first coil means and connected in series with said capacitor, said series combination being coupled to said at least one switching element and being further coupled to said other terminal of said second filament.

Claim 3

Apparatus according to claim 1 further including a trigger generating circuit for supplying a trigger signal to said at least one switching semiconductor element to turn it on, said trigger generating circuit being coupled between the other terminals of said first and second filaments.

Claim 4

Apparatus according to claim 2, wherein: said at least one switching element includes a three-terminal bidirectional switching element; said pulse generating circuit comprises a capacitor and a first resistor connected in parallel with said capacitor, one terminal of said second coil being connected to said one terminal of said AC source and the other terminal of said second coil being connected to the second anode electrode of said three-terminal switching element through said capacitor; said preheating circuit comprises a diode and said three-terminal switching element connected in series with said diode, the anode of said diode being connected to the other terminal of said first filament, the cathode of said diode being connected to the first anode electrode of said three-terminal switching element, and the second anode electrode of said three-terminal switching element being connected to the other terminal of said second filament; and said trigger circuit comprises a series circuit including a second resistor and a two-terminal bidirectional switching element, one terminal of said trigger circuit being connected to the gate electrode of said three-terminal switching element and the other terminal of said two-terminal switching element being connected to the anode electrode of said diode through said second resistor.

Claim 5

Apparatus according to claim 2 wherein said preheating circuit further comprises a third coil connected bEtween said other terminal of said first filament and the anode of said diode, said third coil being differentially inductively coupled to said first coil means.

Claim 6

Apparatus according to claim 1, wherein said at least one switching element includes a three-terminal bidirectional switching element coupled in series with said capacitor and second coil, and said pulse generating circuit further comprises a first resistor connected in parallel with said capacitor, the second anode electrode of said three-terminal switching element being connected to one terminal of said second coil, the other terminal of said second coil being connected to said other terminal of said second filament, and the first anode of said three-terminal switching element being connected to said one terminal of said source through said capacitor.

Claim 7

Apparatus according to claim 5 wherein said preheating circuit comprises a series circuit including said second coil, said three-terminal bidirectional switching element and a diode, the anode of said diode being connected to the first anode of said three-terminal switching element, the second anode of said three-terminal switching element being connected to said other terminal of said second filament through said second coil, the cathode of said diode being connected to said other terminal of said first filament and wherein the trigger circuit comprises a series circuit including a second resistor and a two-terminal bidirectional switching element, one terminal of said two-terminal switching element being connected to the gate of said three-terminal switching element through said second resistor and the other terminal of said two-terminal switching element being connected to the cathode electrode of said diode.

Claim 8

Apparatus according to claim 5 wherein said preheating circuit comprises a series circuit including said second coil, said three-terminal bidirectional switching element and a three-terminal unidirectional switching element, the second anode of said three-terminal bidirectional switching element being connected to said other terminal of said second filament through said second coil, the first anode of said three-terminal bidirectional switching element being connected to the cathode of said three-terminal unidirectional switching element, and the anode of said three-terminal unidirectional switching element being connected to said other terminal of said first filament and wherein said trigger circuit comprises a second resistor and a two-terminal bidirectional switching element coupled in series, a diode and a third resistor coupled in series, one terminal of said two-terminal bidirectional switching element being connected to the gate of said three-terminal switching element through said second resistor, the other terminal of said two-terminal switching element being connected to the anode of said three-terminal unidirectional switching element, the anode of said diode being connected on one terminal of said two-terminal switching element through said third resistor, and the cathode of said diode being connected to the gate electrode of said three-terminal unidirectional switching element.

Claim 9

Apparatus according to claim 2 wherein: said at least one switching element includes a three-terminal unidirectional switching element with its cathode connected to one terminal of said second coil and its anode connected to the other terminal of said first filament, said one terminal of said second coil being further connected to said one terminal of said AC source through said capacitor, the other terminal of said second coil being connected to the other terminal of said second filament; said pulse generating circuit comprises a first resistor connected in parallel with said capacitor; said preheating circuit comprises a series circuit including said second coil and said three-terminal unidirectional switching element, the anode of said three-terminal unidirectional switching element being connected to the other termInal of said first filament, the cathode of said three-terminal unidirectional switching element being coupled to said other terminal of said second filament; and said trigger circuit comprises a series circuit including a diode, a two-terminal bidirectional switching element and a second resistor, one terminal of said two-terminal bidirectional switching element being connected to the anode of said three-terminal unidirectional switching element through said second resistor, the other terminal of said two-terminal bidirectional switching element being connected to the anode of said diode, the cathode of said diode being connected to the gate of said three-terminal unidirectional switching element.

Claim 10

Apparatus according to claim 2 wherein: said preheating circuit comprises a series circuit including said second coil coupled to said first coil means, a three-terminal bidirectional thyristor and a diode, the second anode of said thyristor being connected to said other terminal of said second filament through said second coil, the first anode of said thyristor being connected to the cathode of said diode, the anode of said diode being connected to said other terminal of said first filament; said trigger circuit comprises a series circuit including a trigger resistor and a two-terminal bidirectional switching element, and a trigger capacitor, one terminal of said two-terminal switching element being connected to the gate of said three-terminal switching element, the other terminal of said two-terminal switching element being connected to the anode of said diode through said trigger resistor and to said second coil through said trigger capacitor; and said pulse generating circuit comprises a series circuit including said second coil, said three-terminal bidirectional switching element, a unidirectional semiconductor means having a given polarity and a pulse generating coil, and a pulse generating resistor connected in parallel with said pulse generating diode, said unidirectional semiconductor means being connected between one terminal of said AC source via said capacitor of said pulse generating circuit and the first anode of said three-terminal bidirectional switching element with its polarity being same as that of said diode.

Claim 11

Apparatus according to claim 2 wherein: said preheating circuit comprises a series circuit including a preheating diode, said second coil coupled to said first coil means and a three-terminal bidirectional switching element, the anode of said preheating diode being connected to said other terminal of said first filament, the cathode of said preheating diode being connected via said second coil to the first anode of said three-terminal bidirectional switching element, the second anode thereof being connected to the other terminal of said second filament; said trigger circuit comprises a series circuit including a two-terminal bidirectional switching element and a trigger capacitor, and a trigger resistor, one terminal of said two-terminal switching element being connected to the second anode of said three-terminal bidirectional switching element through said trigger capacitor and to the other terminal of said first filament through said trigger resistor, the other terminal of said two-terminal switching element being connected to the gate of said three-terminal bidirectional switching element; and said pulse generating circuit comprises a series circuit including said three-terminal bidirectional switching element, said second coil, a unidirectional semiconductor means having a given polarity, said capacitor of said pulse generating circuit, and a pulse generating resistor, said unidirectional semiconductor means being connected between the cathode electrode of said diode and one terminal of said AC source through said capacitor of said pulse generating circuit with its polarity being same as that of said diode.

Claim 12

Apparatus according to claim 2 comprising a tapped coil means having a tap point iNtermediate the ends thereof and comprising said second coil, and wherein: said preheating circuit comprises a series circuit including a diode, said tapped coil, and a bidirectional two-terminal thyristor, the anode of said diode being connected to said other terminal of said filament, and the cathode of said diode being connected through said tapped coil to the first anode of said thyristor, the second anode of said thyristor being connected to said other terminal of said filament; said trigger generating circuit comprises a series circuit including a first and second resistor, of which one end is connected to the anode of said diode and the other end is connected to said other terminal of said second filament, a trigger capacitor connected in parallel to the second resistor, and a series circuit consisting of a third resistor and bidirectional two-terminal thyristor of which one end is connected to the juncture between the first and second resistors, and the other end is connected to the gate of said three-terminal thyristor; and said pulse generating circuit comprises a series circuit comprised of a second bidirectional two-terminal thyristor, said second coil which is comprised of the part of said tapped coil means which is defined between the intermediate tap and one end thereof, and said capacitor, and a fourth resistor connected in parallel to said tapped coil means, one end of said second two-terminal thyristor through said part of said tapped coil means and the other end to the first terminal of said AC source through said capacitor.

Claim 13

Apparatus according to claim 11 which further includes another capacitor coupled across said AC source.

Claim 14

Apparatus according to claim 2 comprising a tapped coil means having a tap point intermediate the ends thereof and comprising said second coil, and wherein: said preheating circuit comprises a series circuit including a diode, said tapped coil and a bidirectional three-terminal thyristor, the anode of said diode being connected to said other terminal of said first filament and the cathode of said diode being connected through the part of said tapped coil which is defined between one end thereof and the intermediate tap to the first anode of said three-terminal thyristor, the second anode of said three-terminal thyristor being connected to said other terminal of said filament; said trigger generating circuit includes first and second series coupled resistors, of which one end is connected to the anode of said diode and the other end is coupled to said other terminal of said second filament, a trigger capacitor connected in parallel to the second resistor, and a series circuit comprised of a third resistor and a bidirectional two-terminal thyristor of which one end is connected to the juncture between the first and second resistors, and the other end is connected to the gate of said three-terminal thyristor; and said pulse generating circuit comprises a series circuit including said three-terminal bidirectional thyristor, said second coil which includes at least a portion of said tapped coil, a unidirectional semiconductor means having a given polarity and a second capacitor, and a fourth resistor connected in parallel to said fourth capacitor, one end of said unidirectional semiconductor means being connected to the first anode of said three-terminal thyristor through said second coil and the other end to the first terminal of said AC source through the fourth capacitor with its polarity being same as that of said diode.

Claim 15

Apparatus according to claim 1 wherein: said preheating circuit comprises a series circuit including a first diode, a coil with an intermediate tap magnetically connected to said first coil means and a bidirectional two-terminal thyristor, the anode of said diode being connected to said other terminal of said filament and the cathode of said diode being connected through said tapped coil to one end of said two-terminal thyristor, the other end of said two-terminal thyristor being connected to said other terminal of said second filament; and said pulse generating circuit comprises a series circuit including a resistor, a second diode, said second coil which includes the part of said tapped coil which is defined between one end thereof and the intermediate tap, said bidirectional two-terminal thyristor, and said capacitor connected in parallel to said resistor, the anode of said second diode being connected to the intermediate tap of said tapped coil and the cathode through said capacitor to the first terminal of said AC source.

Claim 16

Apparatus according to claim 14 which further includes a second capacitor coupled across the AC source.

Claim 17

Apparatus according to claim 1 wherein: said preheating circuit comprises a series circuit including a first diode, a coil with an intermediate tap magnetically connected to said first coil means, and a bidirectional two-terminal thyristor, the anode of said diode being connected to said other terminal of said first filament and the cathode of said diode being connected through said tapped coil to one end of said two-terminal thyristor, the other end of said two-terminal thyristor said pulse generating circuit comprises a series circuit including said two-terminal thyristor, said second coil which includes at least a portion of said tapped coil, a second diode and said capacitor, and a resistor connected in parallel to said capacitor, the anode of said second diode being connected to the cathode of said first diode and the cathode of said second diode being connected through said capacitor to said one terminal of AC source.

Claim 18

Apparatus according to claim 16 which further includes another bidirectional two-terminal thyristor connected between the cathode of said first diode and said tapped coil.

Claim 19

Apparatus according to claim 1 wherein: said first coil means has an intermediate tap; said preheating circuit comprises a series circuit including said second coil which is comprised of the part of said first coil means which is defined between one end thereof and the intermediate tap, a second capacitor and a diode, the cathode of said diode being connected to said other terminal of said second filament and the anode of said diode being connected to the intermediate tap of said first coil means through said second capacitor; and said pulse generating circuit includes a series closed circuit comprised of said part of said first coil means between one end thereof and the intermediate tap, and a bidirectional two-terminal semiconductor means with a given polarity.

Claim 20

Apparatus according to claim 1 wherein: said first coil means has an intermediate tap; said preheating circuit comprises a series circuit including a bidirectional two-terminal switching means and a diode, the cathode of the diode being connected to said other terminal of said first filament through said bidirectional two-terminal switching means; said pulse generating circuit comprises a series circuit including said second coil which is comprised of the part of said first coil means which is defined between one end thereof and the intermediate tap, a further coil and said diode, one end of said capacitor being connected to the intermediate tap of said first coil means and the other end of said capacitor being to the anode of said diode.

Claim 21

Apparatus according to claim 19 which further includes a second capacitor coupled across said AC source.