Control circuit for varying the intensity of flash lamps

Claim 2

An electronic circuit for controlling the discharge of stored current through a first, light emitting, discharge device and a second discharge device in shunt therewith comprising: a time delay circuit having an input for connection to the first device and responsive to discharge therethrough to produce a trigger signal a predetermined interval after initiation of discharge, said delay circuit including a plurality of impedances selectively connectable in the delay circuit to vary the length of said interval stepwise, output means for applying the trigger signal to the second device and cause discharge thereof thereby to terminate discharge of the light emitting device, and means connected to the impedances for switching selected impedances in said circuit, whereby the effective intensity of emission from the first device can be varied in predetermined values over substantially the full range of its intensities independently of its instantaneous emission.

Claim 3

A circuit according to claim 1 wherein said time delay circuit comprises a switching device having a control connected to said input, and responsive to a voltage change at said input to initiate current flow through a selected impedance.

Claim 4

A circuit according to claim 2 wherein said switching device comprises the first stage of a one cycle multivibrator with a changing voltage output.

Claim 5

A circuit according to claim 3 wherein said multivibrator includes a time constant network comprising said impedances.

Claim 6

A circuit according to claim 1 wherein said time delay circuit comprises a trigger device with a control causing transmission of the trigger signal when the voltage at said control crosses a threshold value at the trigger control, said impedances being coupled to said control to select said threshold value.

Claim 7

A circuit according to claim 2 wherein said time delay circuit comprises a trigger device connected to said multivibrator and having a control causing transmission of the trigger signal when the multivibrator voltage output crosses a threshold value at the trigger control.

Claim 8

A circuit according to claim 6 wherein said multivibrator includes a time constant network comprising said impedances.

Claim 9

A circuit according to claim 6 wherein said impedances are coupled to said control.

Claim 10

A circuit according to claim 1 wherein said impedances comprise capacitances.

Claim 11

A circuit according to claim 3 wherein said impedances comprise capacitances.

Claim 12

A circuit according to claim 1 wherein said impedances comprise resistances.

Claim 13

A circuit according to claim 5 wherein said impedances comprise resistances.

Claim 14

A circuit according to claim 1 wherein said light emitting discharge device comprises an airport beacon flash lamp.

Claim 15

An airport beacon flash lamp system comprising: a high voltage main storage capacitor; a gas discharge flash lamp and quench tube connected to the storage capacitor in a discharge circuit, each having a control for initiating discharge from the capacitor, discharge of the quench tube terminatin discharge of the flash lamp and limiting the effective intensity of tHe flash; a low voltage, variable time delay circuit having an input connected to the discharge circuit, a plurality of impedances selectively connectable in the time delay circuit, a switching device having a control connected to the input and responsive to initiation of flash lamp discharge to initiate current flow through and a changing voltage at the selected impedance, a trigger device with a control coupled to the selected impedance and having a threshold response to the changing voltage to produce a trigger signal an interval after initiation of flash lamp discharge predetermined by the selected impedance; means for applying the trigger signal to the quench tube control to discharge the quench tube and terminate flash lamp discharge; and an intensity control including relay means for connecting selected impedances in the time delay circuit thereby to vary the interval between flash lamp and quench tube discharge stepwise in predetermined lengths, whereby the effective intensity of flash lamp can be varied substantially over the full range of its intensities independently of its instantaneous emission.

Claim 16

An airport beacon flash lamp system comprising: a high voltage main storage capacitor; a gas discharge flash lamp and quench tube connected to the storage capacitor in a discharge circuit, each having a control for initiating discharge from the capacitor, discharge of the quench tube terminatin discharge of the flash lamp and limiting the effective intensity of tHe flash; a low voltage, variable time delay circuit having an input connected to the discharge circuit, a plurality of impedances selectively connectable in the time delay circuit, a switching device having a control connected to the input and responsive to initiation of flash lamp discharge to initiate current flow through and a changing voltage at the selected impedance, a trigger device with a control coupled to the selected impedance and having a threshold response to the changing voltage to produce a trigger signal an interval after initiation of flash lamp discharge predetermined by the selected impedance; means for applying the trigger signal to the quench tube control to discharge the quench tube and terminate flash lamp discharge; and an intensity control including relay means for connecting selected impedances in the time delay circuit thereby to vary the interval between flash lamp and quench tube discharge stepwise in predetermined lengths, whereby the effective intensity of flash lamp can be varied substantially over the full range of its intensities independently of its instantaneous emission.

Claim 17

A system according to claim 14 wherein said impedances are capacitative.

Claim 18

A system according to claim 14 wherein said impedances are resistive.

Claim 19

A system according to claim 14 wherein said intensity control includes addition relay means for disabling the time delay circuit from applying a trigger signal to the quench tube, thereby allowing the flash tube to emit full intensity.