Flash apparatus

Claim 2

Flash apparatus for use with photographic equipment and the like, which comprises a circuit containing a gaseous arc lamp and a protective current limiting device connected in series across a source of alternating current, triggering means in said circuit which when actuated causes the passage of current from said alternating current source through said lamp to illuminate said lamp, a timing circuit, said timing circuit comprising a primary energy storage capacitor, a source of high voltage to actuate said triggering means and a normally open triggering switch whereby closure of said triggering switch will cause actuation of said source of high voltage by a measured pulse from said primary energy storage capacitor resulting in the actuation of said triggering means and illumination of said lamp every half cycle of said alternating current and means for maintaining said source of high voltage in actuated condition until said primary energy storage capacitor pulse is substantially discharged.

Claim 3

The structure claimed in claim 1 including at least a pair of resistors isolating said timing circuit from said alternating current source, whereby to protect the operator of said photographic equipment from dangerous shock.

Claim 4

The structure claimed in claim 1 including a source of direct current, a pair of resistors being connected across said source of direct current and comprising a voltage divider system, said primary energy storage capacitor being connected to said voltage divider system via a pair of isolating resistors and in such a way as to receive the larger portion of the voltage available from said voltage divider system, said means for maintaining said source of high voltage in actuated condition comprising a silicon controlled rectifier in series with said source of high voltage and with its cathode connected to the negative terminal of said primary energy storage capacitor, the gate of said silicon controlled rectifier being connected through a triggering capacitor and a resistOr in series to the negative terminal of said voltage divider system, a resistor shunting the gate to said cathode of said silicon controlled rectifier whereby to stabilize the triggering characteristics of said silicon controlled rectifier and to provide a return path for the charging current of said triggering capacitor, a protective capacitor in parallel with said silicon controlled rectifier, said triggering switch being connected between the negative terminal of said triggering capacitor and the cathode of said silicon controlled rectifier whereby said source of high voltage will be actuated until said primary energy storage capacitor is substantially discharged, irrespective of the duration of time for which said triggering switch is closed.

Claim 5

The structure claimed in claim 1 wherein said triggering means permitting said passage of current from said source of alternating current through said gaseous arc lamp to illuminate said lamp at full brilliance comprises a first relay contact switch, a high voltage step-up transformer, a spark gap, an excitation capacitor, a radio frequency transformer and a triggering electrode for said gaseous arc lamp, said first relay contact switch and the primary of said high voltage transformer being connected in series across said source of alternating current, the secondary of said high voltage transformer having at one end two leads, the first of said leads being connected to a spark gap, the second of said leads containing in series said excitation capacitor and the primary of said radio frequency transformer, the secondary of said radio frequency transformer being connected to said trigger electrode, a relay having an armature, said first relay contact switch being normally open and being movable to a closed position when said relay is actuated, said relay being connected to said primary energy storage capacitor through said triggering switch.

Claim 6

The structure claimed in claim 4 wherein said means for maintaining said relay in actuated condition comprises a second relay contact switch forming a part of said relay, said second relay contact switch being normally open and being movable to a closed position by the slightest movement of said armature when said relay is actuated, said relay also being connected to said primary energy storage capacitor through said second relay contact switch whereby said relay will be connected to said primary energy storage capacitor and said first and second relay contact switches will remain closed until said primary energy storage capacitor is substantially discharged, irrespective of the duration of time for which said triggering switch is closed.

Claim 7

The structure claimed in claim 4 wherein said means for maintaining said relay in actuated condition comprises a silicon controlled rectifier in series with said relay, the gate of said silicon controlled rectifier being connected to said primary energy storage capacitor through said triggering switch and a resistor in series whereby said relay will be actuated and said first relay contact switch will be closed until said primary energy storage capacitor is substantially discharged, irrespective of the duration of time for which said triggering switch is closed.

Claim 8

The structure claimed in claim 4 including a source of direct current, a pair of resistors being connected across said source of direct current and comprising a voltage divider system, said primary energy storage capacitor being connected to said voltage divider system via a pair of isolating resistors and in such a way as to receive the larger portion of the voltage available from said voltage divider system, said means for maintaining said relay in actuated condition comprising a silicon controlled rectifier in series with said relay and with its cathode connected to the negative terminal of said primary energy storage capacitor, the gate of said silicon controlled rectifier being connected through a triggering capacitor and a resistor in series to the negative terminal of said vOltage divider system, a resistor shunting the gate to said cathode of said silicon controlled rectifier whereby to stabilize the triggering characteristics of said silicon controlled rectifier and to provide a return path for the charging current of said triggering capacitor, said triggering switch being connected between the negative terminal of said triggering capacitor and the cathode of said silicon controlled rectifier whereby said relay will be actuated and said first relay contact switch will be closed until said primary energy storage capacitor is substantially discharged, irrespective of the duration of time for which said triggering switch is closed.

Claim 9

The structure claimed in claim 5 wherein said timing circuit is isolated from said main source of alternating current by a pair of resistors, and including a lead connected across said source of alternating current and containing a rectifier and a second capacitor in series, said rectifier and second capacitor combination being connected through said pair of resistors to said primary energy storage capacitor and constituting said source of direct current from which said first capacitor is charged.

Claim 10

The structure claimed in claim 6 wherein said timing circuit is isolated from said source of alternating current by a pair of resistors, and including a lead connected across said source of alternating current and containing a rectifier and a second capacitor in series, said rectifier and second capacitor combination being connected through said pair of resistors to said primary energy storage capacitor and constituting said source of direct current from which said first capacitor is charged.

Claim 11

The structure claimed in claim 1 wherein said source of high voltage comprises an interrupter switch and an inductive device, said interrupter switch adapted to make and break current through said inductive device.

Claim 12

The structure claimed in claim 10 wherein said interrupter switch comprises a single reed, vacuum enclosed switch, said inductive device comprising a coil, said vacuum enclosed interrupter switch being series connected with said coil, said coil surrounding said vacuum enclosed interrupter switch, said interrupter switch being magnetically biased whereby to have good sensitivity to the magnetic field provided by said surrounding coil.

Claim 13

The structure claimed in claim 1 wherein said means for maintaining said source of high voltage energized comprises a second capacitor connected in parallel with said primary energy storage capacitor and said source of high voltage, said triggering switch being connected between said primary energy storage capacitor and said second capacitor whereby said source of high voltage will be energized and said triggering means will be energized until said second capacitor is substantially discharged irrespective of the duration of time for which said triggering switch is closed.

Claim 14

The structure claimed in claim 12 wherein said timing circuit is isolated from said source of alternating current by a pair of resistors, and including a lead connected across said source of alternating current and containing a rectifier and third capacitor in series, said rectifier and third capacitor combination being connected through one of said resistors to said primary energy storage capacitor and constituting a source of direct current from which said primary energy storage capacitor is charged.

Claim 15

The structure claimed in claim 1 wherein said means for maintaining said source of high voltage in actuated condition comprises a silicon controlled rectifier in series with said source of high voltage, a protective capacitor in parallel with said silicon controlled rectifier, the gate of said silicon controlled rectifier being connected to said primary energy storage capacitor through said triggering switch and a resistor in series whereby said source of high voltage will be actuated until said primary energy storage capacitor is substantially discharged irrespective of the duration Of time for which said triggering switch is closed.

Claim 16

The structure claimed in claim 14 wherein said timing circuit is isolated from said main source of alternating current by a pair of resistors, and including a lead connected across said source of alternating current and containing a rectifier and a second capacitor in series, said rectifier and second capacitor combination being connected through said pair of resistors to said primary energy storage capacitor and constituting a source of direct current from which said primary energy storage capacitor is charged.