Circuit for starting and maintaining a discharge through a gas discharge tube

Claim 2

In a circuit for starting and maintaining a discharge through a gas discharge tube having a cathode electrode and anode electrode, said circuit comprising a positive terminal and a negative terminal connectable to a DC power supply, coupling means for coupling said positive terminal to said anode electrode and for coupling said negative terminal to said cathode electrode, an igniter adapted to be coupled in cooperative relationship with said tube for starting a discharge therethrough in response to energization thereof by an ignition voltage when said igniter is coupled to said tube, and selectively operable means coupled to said igniter for supplying said ignition voltage only when operated; the combination therewith of a capacitance, and means including said coupling means effective when said coupling means are coupled to said electrodes of said tube for charging said capacitance with said power supply to a given voltage in response to said selectively operable means being unoperated and in the absence of a discharge through said tube, for serially coupling said power supply terminals and said capacitance across said cathode and anode electrodes of said tube to apply the output of said power supply and said given voltage thereto in series-aiding relationship in response to said selectively operable means being operated, for discharging said capacitance through said tube upon the start of a discharge therethrough, and for coupling solely said power supply terminals across said cathode and anode electrodes of said tube to apply thereto only said power supply output upon the completion of the discharge of said capacitance.

Claim 3

The combination defined in claim 1, wherein said coupling means includes a unidirectional conducting device connected between one terminal of said power supply and the one of said electrodes of said tube coupled to that terminal, said unidirectional conducting device being poled to be normally conductive, and wherein said means including said coupling means comprises a capacitance charging resistance connected between the other of said electrodes of said tube and one end of said capacitance, means excluding said unidirectIonal conducting device connecting the other end of said capacitance to said one electrode, and a pair of switch contacts under the control of said selectively operable means for connecting said one end of said capacitance to said one terminal solely when said selectively operable means is operated.

Claim 4

The combination defined in claim 2, wherein said means connecting the other end of said capacitance to said one electrode includes a current-limiting resistance.

Claim 5

The combination defined in claim 2, wherein said means including said coupling means further comprises a shunt resistance shunting said capacitance.

Claim 6

The combination defined in claim 2, wherein said coupling means further comprises second pair of switch contacts under the control of said selectively operable means for connecting said one terminal directly to said one electrode solely when said selectively operable means is unoperated.

Claim 7

The combination defined in claim 1, wherein said gas discharge tube is a gas laser tube.

Claim 8

The combination defined in claim 1, wherein said power supply is a current-regulated power supply.

Claim 9

The combination defined in claim 1, wherein the output of said power supply is insufficient in and as of itself to effect starting of discharge through said tube, but is sufficient to maintain discharge therethrough once started, and the sum of the output of said power supply and said given voltage is sufficient to effect starting of discharge through said tube.

Claim 10

A circuit for starting and maintaining a discharge through a gas laser tube having a cathode electrode and an anode electrode; said circuit comprising a DC power supply having a negative terminal connected directly to said cathode electrode; a unidirectional conducting device connecting a positive terminal of said power supply to said anode electrode, said unidirectional conducting device being poled to be normally conducting; a voltage divider comprising a first relatively high resistance having one end thereof connected to said cathode electrode, a second relatively high resistance having one end thereof connected to the other end of said first resistance, and a third relatively low resistance having one end thereof connected to the other end of said second resistance and the other end of said third resistance connected to said anode electrode; a capacitance having one end thereof connected to the junction of said first and second resistances and the other end thereof connected to the junction of said second and third resistances; a contactor having a normally closed pair of switch contacts, a normally open pair of switch contacts, and a contact-actuating coil; means for connecting said normally closed pair of contacts between said positive terminal and said anode electrode; means for connecting said normally open pair of contacts between said positive terminal and said one end of said capacitance; an igniter coil in cooperative relationship with said gas laser tube, said igniter coil being connected in parallel with said contact-actuating coil; and a control circuit for said parallel connected igniter and contact-actuating coils including a normally open manually operated switch for applying an AC voltage to said parallel-connected ignitor and contact-actuating coils in response to the closure of said manually operated switch.

Claim 11

A circuit for starting and maintaining a discharge through a gas laser tube having a cathode electrode and an anode electrode; said circuit comprising a DC power supply having a negative terminal connected directly to said cathode electrode; a unidirectional conducting device connecting a positive terminal of said power supply to said anode electrode, said unidirectional conducting device being poled to be normally conducting; a voltage divider comprising a first relatively high resistance having one end thereof connected to said cathode electrode, a second relatively high resistance having one end thereof connected to the other end of said first resistance, and a third relatively low resistance having one end thereof connected to the other end of said second resistance and the other end of said third resistance connected to said anode electrode; a capacitance having one end thereof connected to the junction of said first and second resistances and the other end thereof connected to the junction of said second and third resistances; a contactor having a normally closed pair of switch contacts, a normally open pair of switch contacts, and a contact-actuating coil; means for connecting said normally closed pair of contacts between said positive terminal and said anode electrode; means for connecting said normally open pair of contacts between said positive terminal and said one end of said capacitance; an igniter coil in cooperative relationship with said gas laser tube, said igniter coil being connected in parallel with said contact-actuating coil; and a control circuit for said parallel connected igniter and contact-actuating coils including a normally open manually operated switch for applying an AC voltage to said parallel-connected ignitor and contact-actuating coils in response to the closure of said manually operated switch.