Phase controlled firing circuit

Claim 2

Apparatus for use with an alternating current source to provide an output pulse at a predetermined phase of the alternating source comprising: silicon controlled rectifier means having anode, cathode, and gate terminals, which rapidly turns on to decrease in anode to cathode resistance when there is a predetermined gate to cathode voltage; an initiating capacitor having a first terminal coupled to said cathode terminal and a second terminal; means coupling said second terminal of said capacitor to said anode of said silicon controlled rectifier means, so that the voltage across said capacitor changes by the flow of a current pulse through it and through said rectifier means when said rectifier means is turned on; impedance means coupled to said alternating current source for supplying current to said capacitor that changes the voltage across it and to provide a controlled gate voltage, said impeance means including a resistor and means coupling one side of said resistor to said current source and the other side of said resistor to said capacitor to provide a net change in capacitor voltage over each cycle of said alternating current source that lowers the potential of said first capacitor terminal and cathode terminal with respect to said gate terminal.

Claim 3

The apparatus described in claim 1 wherein: said means coupling said second terminal of said capacitor to said anode of said silicon controlled rectifier means includes a second capacitor; and including means for charging said second capacitor, so that said initiating capacitor is rapidly charged from said second capacitor when said rectifier means is turned on.

Claim 4

The apparatus described in claim 1 wherein: said alternating current sourCe has a ground terminal and a second source terminal and defines an alternating voltage therebetween; and including second capacitor means for maintaining the anode terminal of said silicon controlled rectifier means at a voltage above said ground terminal during a period prior to said rectifier means turning on; and wherein said resistor of said impedance means couples said gate terminal to said second source terminal of said alternating current source, whereby to fire said silicon controlled rectifier means and provide an output pulse, near a positive peak of the alternating current source.

Claim 5

The apparatus described in claim 1 wherein: said alternating current source has a ground terminal and a second source terminal and defines an alternating voltage therebetween; and including second capacitor means for maintaining the anode terminal of said silicon controlled rectifier means at a voltage above said ground terminal during a period prior to said rectifier means turning on; and wherein said resistor of said impedance means couples said gate terminal to said ground terminal, and said impedance means also includes ripple-producing means of predetermined impedance coupling said first capacitor terminal to said second terminal of said alternating current source, whereby to fire said silicon controlled rectifier means during a negative portion of the alternating current voltage.

Claim 6

The apparatus described in claim 1 including: phase shift means for connection to said alternating current source to provide a varying voltage which varies as said current source varies but with a phase shift; and said impedance means is coupled to said alternating current source through said phase shift means to provide a gate voltage that varies out of phase with said alternating current source.

Claim 7

The apparatus described in claim 1 including: a second silicon controlled rectifier means having a second anode, cathode and gate terminals, and which rapidly decreases in anode to cathode resistance when there is a predetermined gate to cathode voltage; a second initiating capacitor having a first terminal coupled to said second cathode terminal and a second terminal; second means coupling said second terminal of said second capacitor to said second anode; second impedance means coupled to said alternating current source for supplying current to said second capacitor that changes the voltage across it and to provide a controlled gate voltage; and an intercircuit capacitance coupling said first-named initiating capacitor and said second initiating capacitor.

Claim 8

In a power supply which includes an alternating voltage source, storage means for providing a voltage of constant polarity, silicon controlled rectifier means having an anode connected to a positive terminal of said storage means, a cathode, and a gate, striking circuit means, an initiating capacitor, and means coupling the cathode to the anode by way of the striking circuit means, so that when the gate voltage is above the cathode voltage the silicon controlled rectifier means fires to provide a sudden current flow through the capacitor for activating the striking means, the combination comprising: a resistor with first and second terminals; means for coupling said first resistor terminal to said voltage source; and means for coupling said second resistor terminal to said gate of said silicon controlled rectifier means, to provide a gate voltage that varies in constant phase relationship to said voltage source and a current for flow substantially between said gate of said rectifier means and said cathode thereof to change the charge on said initiating capacitor in a direction that lowers the voltage of the initiating capacitor terminal which is coupled to the cathode of the silicon controlled rectifier means.

Claim 9

In a power supply which includes an alternating voltage source, storage means for providing a voltage of constant polarity, silicon controlled rectifier means having an anode connected to a positive terminal of said storage means, a cathode, and a gate, striking circuit means, an initiating capacitor, and means coupling the cathode to the anode by way of the striking circuit means, so that when the gate voltage is above the cathode voltage the silicon controlled rectifier means fires to provide a sudden current flow through the capacitor for activating the striking means, the combination comprising: a resistor with first and second terminals; means for coupling said first resistor terminal to said voltage source; and means for coupling said second resistor terminal to said gate of said silicon controlled rectifier means, to provide a gate voltage that varies in constant phase relationship to said voltage source and a current for flow substantially between said gate of said rectifier means and said cathode thereof to change the charge on said initiating capacitor in a direction that lowers the voltage of the initiating capacitor terminal which is coupled to the cathode of the silicon controlled rectifier means.

Claim 10

In a power supply which includes a point of substantially constant voltage, an alternating voltage source for supplying a voltage which alternates in polArity with respect to said point of constant voltage, storage means for providing a voltage of constant polarity, silicon controlled rectifier means having an anode connected to a positive terminal of said storage means, a cathode, and a gate, striking circuit means, an initiating capacitor, and means coupling the cathode to the anode through windings by way of the striking circuit means, so that when the gate voltage is above the cathode voltage the silicon controlled rectifier means fires to provide a sudden current flow through the capacitor for activating the striking means, the combination comprising: a resistor coupling said gate of said silicon controlled rectifier means to said point of substantially constant voltage, and an impedance having one terminal coupled to a point on said voltage source which varies in voltage at the same frequency as said alternating voltage source and at a constant phase relationship therewith and a second terminal; and means coupling said second terminal of said impedance to said cathode of said silicon controlled rectifier means, to provide a ripple voltage thereon.

Claim 11

In a power supply which includes a point of substantially constant voltage, an alternating voltage source for supplying a voltage which alternates in polArity with respect to said point of constant voltage, storage means for providing a voltage of constant polarity, silicon controlled rectifier means having an anode connected to a positive terminal of said storage means, a cathode, and a gate, striking circuit means, an initiating capacitor, and means coupling the cathode to the anode through windings by way of the striking circuit means, so that when the gate voltage is above the cathode voltage the silicon controlled rectifier means fires to provide a sudden current flow through the capacitor for activating the striking means, the combination comprising: a resistor coupling said gate of said silicon controlled rectifier means to said point of substantially constant voltage, and an impedance having one terminal coupled to a point on said voltage source which varies in voltage at the same frequency as said alternating voltage source and at a constant phase relationship therewith and a second terminal; and means coupling said second terminal of said impedance to said cathode of said silicon controlled rectifier means, to provide a ripple voltage thereon.

Claim 12

In a stroboscopic lamp initiating circuit which includes a power supply having a predetermined location with a varying voltage thereon, means for coupling said power supply to a stroboscopic lamp to supply a voltage across the lamp that varies in amplitude in phase with variations in voltage at said predetermined location but which supplies a higher peak voltage at the lamp than the peak voltage at said location, and lamp striker means, the combination comprising: silicon controlled rectifier means having an anode, a cathode, and a gate, said rectifier means turning on when there is a predetermined gate to cathode firing voltage and said rectifier means defining a gate-to-cathode diode which can conduct a reverse current; initiating means including an initiating capacitor and means responsive to a current pulse through said capacitor for operating said striker means, said initiating means coupling said cathode to said anode; and impedance means coupling said gate to said predetermined location of said power supply, to provide a reverse current through said diode of said rectifier means that changes the charge on said capacitor at each cycle of said varying voltage of said power supply, and to provide a voltage at said gate that turns on said rectifier means when the charge on said capacitor has been sufficiently changed, said impedance means having an impedance high enough to change the voltage across said capacitor to a voltage that enables turning on of said rectifier means only after a plurality of cycles of said A.C. source, whereby to assure striking of the lamp at close to a peak of the varying voltage across the lamp.

Claim 13

In a stroboscopic lamp initiating circuit which includes a power supply having a predetermined location with a varying voltage thereon, means for coupling said power supply to a stroboscopic lamp to supply a voltage across the lamp that varies in amplitude in phase with variations in voltage at said predetermined location but which supplies a higher peak voltage at the lamp than the peak voltage at said location, and lamp striker means, the combination comprising: silicon controlled rectifier means having an anode, a cathode, and a gate, said rectifier means turning on when there is a predetermined gate to cathode firing voltage and said rectifier means defining a gate-to-cathode diode which can conduct a reverse current; initiating means including an initiating capacitor and means responsive to a current pulse through said capacitor for operating said striker means, said initiating means coupling said cathode to said anode; and impedance means coupling said gate to said predetermined location of said power supply, to provide a reverse current through said diode of said rectifier means that changes the charge on said capacitor at each cycle of said varying voltage of said power supply, and to provide a voltage at said gate that turns on said rectifier means when the charge on said capacitor has been sufficiently changed, said impedance means having an impedance high enough to change the voltage across said capacitor to a voltage that enables turning on of said rectifier means only after a plurality of cycles of said A.C. source, whereby to assure striking of the lamp at close to a peak of the varying voltage across the lamp.

Claim 14

In a stroboscopic lamp initiating circuit including an A.C. voltage source and striking means, the combination comprising: voltage storage means including a power capacitor for supplying current to light said lamp and a circuit portion for charging said power capacitor from said A.C. voltage source to establish a first terminal of said power capacitor positive with respect to a second terminal thereof, said circuit portion capable of supplying current directly to said lamp during at least a portion of a positive A.C. cycle if the lamp is struck during said portion, but not during a negative portion of an A.C. cycle; silicon controlled rectifier means having an anode coupled to said first power capacitor terminal, a cathode, and a gate, said rectifier means turning on when there is a positive gate-to-cathode voltage to permit a large anode to cathode current flow; initiating means including an initiating capacitor coupling said cathode to said anode and means responsive to a current pulse through said capacitor for operating said striking means; and impedance means coupled to said voltage source for establishing a voltage at said gate, and for carrying a ripple current to said capacitOr that varies in constant phase relationship with said A.C. source so that the voltage at the cathode decreases at every cycle of the A.C. voltage source with a ripple component that is in constant phase relationship with the A.C. voltage source, to lower the cathode voltage below the gate voltage and thereby cause lamp striking only during a negative portion of the A.C. cycle, thereby to prevent the flow of lamp current directly through said circuit portion that charges the power capacitor.

Claim 15

In a stroboscopic lamp initiating circuit including an A.C. voltage source and striking means, the combination comprising: voltage storage means including a power capacitor for supplying current to light said lamp and a circuit portion for charging said power capacitor from said A.C. voltage source to establish a first terminal of said power capacitor positive with respect to a second terminal thereof, said circuit portion capable of supplying current directly to said lamp during at least a portion of a positive A.C. cycle if the lamp is struck during said portion, but not during a negative portion of an A.C. cycle; silicon controlled rectifier means having an anode coupled to said first power capacitor terminal, a cathode, and a gate, said rectifier means turning on when there is a positive gate-to-cathode voltage to permit a large anode to cathode current flow; initiating means including an initiating capacitor coupling said cathode to said anode and means responsive to a current pulse through said capacitor for operating said striking means; and impedance means coupled to said voltage source for establishing a voltage at said gate, and for carrying a ripple current to said capacitOr that varies in constant phase relationship with said A.C. source so that the voltage at the cathode decreases at every cycle of the A.C. voltage source with a ripple component that is in constant phase relationship with the A.C. voltage source, to lower the cathode voltage below the gate voltage and thereby cause lamp striking only during a negative portion of the A.C. cycle, thereby to prevent the flow of lamp current directly through said circuit portion that charges the power capacitor.

Claim 16

The combination described in claim 10 wherein: said silicon controlled rectifier means is constructed so that it can carry a reversed biased cathode-to-gate current; and said impedance means includes a resistor coupling said gate to a location on said circuit portion of constant potential, to provide an exponential charging current, and a ripple-producing impedance coupling a terminal of said initiating capacitor to a location on said circuit portion which varies in voltage in phase with said A.C. source to provide a ripple charging current that adds to said exponential charging current.

Claim 17

A lamp firing circuit for striking and energizing a stroboscopic lamp that has a predetermined maintenance voltage below which the lamp becomes extinguished, from an A.C. source with first and second source terminals that alternate in relative polarity at every half cycle and which obtain a peak voltage exceeding said maintenance voltage of said lamp, comprising: a power capacitor with first and second capacitor terminals; a diode; means for coupling said diode and capacitor in series to said A.C. source to charge said capacitor, so that said first capacitor terminal becomes positive with respect to said second capacitor terminal and so that the charge on said capacitor can increase only during portions of the A.C. source half cycle when said first source terminal is positive with respect to said second source terminal; means for connecting said capacitor across said stroboscopic lamp, so that said capacitor can provide lamp energizing current when the lamp is struck; and means responsive to said A.C. source for striking said lamp only during those times of each A.C. source cycle when the voltage at said first source terminal minus the voltage at said second source terminal is less than said lamp maintenance voltage, whereby to prevent the flow of lamp current directly from said A.C. source.

Claim 18

A lamp firing circuit for striking and energizing a stroboscopic lamp that has a predetermined maintenance voltage below which the lamp becomes extinguished, from an A.C. source with first and second source terminals that alternate in relative polarity at every half cycle and which obtain a peak voltage exceeding said maintenance voltage of said lamp, comprising: a power capacitor with first and second capacitor terminals; a diode; means for coupling said diode and capacitor in series to said A.C. source to charge said capacitor, so that said first capacitor terminal becomes positive with respect to said second capacitor terminal and so that the charge on said capacitor can increase only during portions of the A.C. source half cycle when said first source terminal is positive with respect to said second source terminal; means for connecting said capacitor across said stroboscopic lamp, so that said capacitor can provide lamp energizing current when the lamp is struck; and means responsive to said A.C. source for striking said lamp only during those times of each A.C. source cycle when the voltage at said first source terminal minus the voltage at said second source terminal is less than said lamp maintenance voltage, whereby to prevent the flow of lamp current directly from said A.C. source.

Claim 19

The circuit described in claim 12 wherein: said means for connecting said capacitor across said lamp includes a diode coupling said second capacitor terminal to a second of said lamp terminals, to prevent current flow in a direction from said second capacitor terminal to said second lamp terminal; and including means for applying a varying voltage to said lamp that reduces the voltage at said second lamp terminal below the voltage at said second capacitor terminal in phase with said A.C. source; and wherein said means for striking is constructed to fire said lamp at times when the potential at said second lamp terminal is near a negative peak with respect to the voltage at said second capacitor terminal.

Claim 20

A stroboscopic lamp firing circuit for striking and firing a stroboscopic lamp from an A.C. source comprising: a capacitor with first and second capacitor terminals; a diode; first and second circuit terminals for connecting to first and second terminals of said A.C. source; means for coupling said capacitor and diode in series to said circuit terminals, with said diode allowing current flow only in a direction from said first circuit terminal to said first capacitor terminal, for charging said capacitor so that said first capacitor terminal becomes positive with respect to said second capacitor terminal; means for coupling said capacitor across said lamp, so that said capacitor can provide lamp energizing current when the lamp is struck; and means coupled to said circuit terminals For striking said lamp only during times when said first circuit terminal is negative with respect to said second circuit terminal whereby to prevent the flow of lamp current directly from said A.C. source.

Claim 21

A stroboscopic lamp firing circuit for striking and firing a stroboscopic lamp from an A.C. source comprising: a capacitor with first and second capacitor terminals; a diode; first and second circuit terminals for connecting to first and second terminals of said A.C. source; means for coupling said capacitor and diode in series to said circuit terminals, with said diode allowing current flow only in a direction from said first circuit terminal to said first capacitor terminal, for charging said capacitor so that said first capacitor terminal becomes positive with respect to said second capacitor terminal; means for coupling said capacitor across said lamp, so that said capacitor can provide lamp energizing current when the lamp is struck; and means coupled to said circuit terminals For striking said lamp only during times when said first circuit terminal is negative with respect to said second circuit terminal whereby to prevent the flow of lamp current directly from said A.C. source.