Electronic flash coupling system for sequential flashbulb firing circuit

Claim 2

An electronic flash unit for use with a camera having an accessory connector adapted to receive at least one flashlamp and having terminals adapted to be supplied with current for firing a flashlamp, said electronic flash unit comprising a triggerable gas discharge tube, means for supplying electrical energy to said tube to cause said tube to produce a flash of light when triggered, trigger circuit means connected to said tube and responsive to an applied signal to trigger said tube, and a signal generating impedance network having input terminals adapted to be connected to the current supply terminals of the camera, said network comprising a resistance approximating the resistance of an unfired flashlamp connected in series with a capacitor between said input terminals, whereby current supplied to said input terminals flows in a pulse that falls in amplitude as said capacitor is charged, simulating the impedance characteristics of a flashlamp as it is fired, said impedance network further comprising means responsive to the flow of current through said capacitor to apply a signal to said trigger circuit means.

Claim 3

A photoelectrical trigger and flashlamp simulating circuit for an electronic flash unit, comprising a pair of input terminals adapted to be connected to a DC source, a capacitor and a first resistor having a resistance approximating the resistance of an unfired flashlamp connected in series between said terminals, a light-emitting diode and a second resistor connected in series across said first resistor, and a third resistor having a resistance high enough to simulate an open circuit connected across said capacitor.

Claim 4

A photoelectrical trigger and flashlamp simulating circuit for an electronic flash unit, comprising a pair of input terminals adapted to be connected to a DC source, a capacitor and a first resistor having a resistance approximating the resistance of an unfired flashlamp connected in series between said terminals, a light-emitting diode and a second resistor connected in series across said first resistor, and a third resistor having a resistance high enough to simulate an open circuit connected across said capacitor.

Claim 5

An electronic flash unit for a camera having a pair of output terminals adapted to supply current to fire a flashlamp and provided with means responsive to impedance changes across the output terminals to control the cycle of operation of the camera, said flash unit comprising first and second input terminals adapted to be connected to the output terminals of the camera, triggerable light source means responsive to an applied trigger signal for producing a flash of light, and a flashlamp simulating and trigger signal producing network connected between said input terminals, said network having an impedance that increases from a value simualting an unfired flashlamp to a value simulating a fired flashlamp in response to direct current applied to said input terminals, and said network further comprising means responsive to the flow of current for producing a trigger signal and applying said trigger signal to said light source means.

Claim 6

An electronic flash unit for a camera having a pair of output terminals adapted to supply current to fire a flashlamp and provided with means responsive to impedance changes across the output terminals to control the cycle of operation of the camera, said flash unit comprising first and second input terminals adapted to be connected to the output terminals of the camera, triggerable light source means responsive to an applied trigger signal for producing a flash of light, and a flashlamp simulating and trigger signal producing network connected between said input terminals, said network having an impedance that increases from a value simualting an unfired flashlamp to a value simulating a fired flashlamp in response to direct current applied to said input terminals, and said network further comprising means responsive to the flow of current for producing a trigger signal and applying said trigger signal to said light source means.

Claim 7

An electronic flash unit, comprising a housing, a reflector mounted in said housing, a gas discharge tube mounted in said reflectOr, photoelectric circuit means responsive to a light signal to energize said discharge tube to produce a flash of light, an electrical connector on said housing having a pair of terminals adapted to be energized with direct current, a resistor and a capacitor connected in series with said terminals, and light signal generating means in optical communication with said photoelectric circuit means connected in parallel with said resistor and responsive to applied current to apply a light signal to said photoelectric circit means.

Claim 8

An electronic flash unit, comprising a housing, a reflector mounted in said housing, a gas discharge tube mounted in said reflectOr, photoelectric circuit means responsive to a light signal to energize said discharge tube to produce a flash of light, an electrical connector on said housing having a pair of terminals adapted to be energized with direct current, a resistor and a capacitor connected in series with said terminals, and light signal generating means in optical communication with said photoelectric circuit means connected in parallel with said resistor and responsive to applied current to apply a light signal to said photoelectric circit means.

Claim 9

An electronic flash unit adapted for use with a camera having output terminals, means for applying a direct voltage to the output terminals, and means for sensing a drop in current across the output terminals to terminate an exposure cycle, said flash unit comprising first and second terminals adapted to be connected to the output terminals of the camera, a third terminal, a first resistor connected between said first and third terminals, a capacitor connected between said third terminal and said second terminal, a second resistor and a light-emitting diode connected in series between said first terminal and said third terminal, a third resistor connected between said third terminal and said second terminal, said first and second resistors having resistances selected to make the resistance between said first and third terminals approximately the resistance of an unfired flashlamp, said third resistor having a resistance high enough to simulate an open circuit to the camera, an electronic flash circuit responsive to an applied trigger signal to produce a flash of illuminating light, and a light responsive signal generator confronting said light-emitting diode and responsive to light emitted by said diode in response to a surge of current between said first and third terminals for applying a trigger signal to said flash circuit.

Claim 10

An electronic flash unit adapted for use with a camera having output terminals, means for applying a direct voltage to the output terminals, and means for sensing a drop in current across the output terminals to terminate an exposure cycle, said flash unit comprising first and second terminals adapted to be connected to the output terminals of the camera, a third terminal, a first resistor connected between said first and third terminals, a capacitor connected between said third terminal and said second terminal, a second resistor and a light-emitting diode connected in series between said first terminal and said third terminal, a third resistor connected between said third terminal and said second terminal, said first and second resistors having resistances selected to make the resistance between said first and third terminals approximately the resistance of an unfired flashlamp, said third resistor having a resistance high enough to simulate an open circuit to the camera, an electronic flash circuit responsive to an applied trigger signal to produce a flash of illuminating light, and a light responsive signal generator confronting said light-emitting diode and responsive to light emitted by said diode in response to a surge of current between said first and third terminals for applying a trigger signal to said flash circuit.

Claim 11

The apparatus of claim 5 in which said electronic flash circuit comprises a second capacitor, a gas tube having a pair of electrodes connected across said second capacitor and a trigger electrode, means for charging said second capacitor, means responsive to a predetermined voltage across said capacitor for producing a supply voltage, and trigger pulse generating means comprising an electronic switch and circuit means responsive to the closing of said switch for applying a trigger pulse to said trigger electrode to discharge said second capacitor through said gas tube and produce a flash of light, and in which said light-responsive signal generator comprises a light-responsive diode arranged to be illuminated by said light-emitting diode and means for applying said supply voltage to said electronic switch through said light-responsive diode to close said electronic switch when said supply voltage is present and said light-responsive diode is illuminated by a flash from said light-emitting diode.

Claim 12

In an electronic flash unit, a triggerable discharge tube, photoelectric triggering means responsive to a flash of light for triggering said tube, and a flashlamp simulating and light flash generating circuit for coupling said photoelectric triggering means to a camera adapted for use with flashlamps and having output terminals adapted to be supplied with DC voltage when a flashlamp is to be fired, said circuit comprising input terminals adapted to be connected to the output terminals of the camera, and an impedance network connected between said input terminals, said impedance network having an impedance that rises from an initial value simulating the impedance of an unfired flashlamp to a higher value simulating the impedance of a fired flashlamp, whereby a pulse of current flows through said network in response to a DC voltage applied to said input terminals, said impedance network comprising a light-emitting diode optically coupled to said photoelectric triggering means for transmitting a flash of light to said triggering means in response to the flow of current through said network.

Claim 13

In an electronic flash unit, a triggerable discharge tube, photoelectric triggering means responsive to a flash of light for triggering said tube, and a flashlamp simulating and light flash generating circuit for coupling said photoelectric triggering means to a camera adapted for use with flashlamps and having output terminals adapted to be supplied with DC voltage when a flashlamp is to be fired, said circuit comprising input terminals adapted to be connected to the output terminals of the camera, and an impedance network connected between said input terminals, said impedance network having an impedance that rises from an initial value simulating the impedance of an unfired flashlamp to a higher value simulating the impedance of a fired flashlamp, whereby a pulse of current flows through said network in response to a DC voltage applied to said input terminals, said impedance network comprising a light-emitting diode optically coupled to said photoelectric triggering means for transmitting a flash of light to said triggering means in response to the flow of current through said network.

Claim 14

In combination with an electronic flash circuit of the type including a ready lamp which conducts when the flash circuit is charged in readiness to be triggered and a triggering circuit having first and second terminals and responsive to current applied to said terminals for triggering the flash circuit to produce a brilliant flash of light, a photoelectric circuit for supplying current to said terminals when and only when said ready light is conducting and a low level light flash is emitted, said photoelectric circuit comprising a resistor connected in series with said ready light, whereby current flows through said resistor when said ready light is conducting, and a light-responsive diode connected in a series path with said terminals and said resistor, whereby current is applied to said terminals when and only when said light-responsive diode is illuminated and said ready light is conducting.

Claim 15

In combination with an electronic flash circuit of the type including a ready lamp which conducts when the flash circuit is charged in readiness to be triggered and a triggering circuit having first and second terminals and responsive to current applied to said terminals for triggering the flash circuit to produce a brilliant flash of light, a photoelectric circuit for supplying current to said terminals when and only when said ready light is conducting and a low level light flash is emitted, said photoelectric circuit comprising a resistor connected in series with said ready light, whereby current flows through said resistor when said ready light is conducting, and a light-responsive diode connected in a series path with said terminals and said resistor, whereby current is applied to said terminals when and only when said light-responsive diode is illuminated and said ready light is conducting.

Claim 16

An electronic flash unit, comprising first and second input terminals adapted to be energized with a DC voltage when an illuminating flash is to be produced, a third terminal, a resistor having a resistance approximating the impedance of an unfired flashlamp connected between said first terminal and said third terminal, a capacitor connected between said second terminal and said third terminal, a light-emitting diode, means connecting said light-emitting diode between said first terminal and said third terminal to produce a flash of light upon the application of a DC voltage to said first and second terminals, a flash circuit comprising a triggerable gas discharge tube, means for supplying energy to said discharge tube to cause said tube to emit an illuminating flash of light when triggered, and circuit means comprising a light-responsive switch confronting said light-emitting diode for triggering said flash circuit when a flash of light is emitted by said light-emitting diode.

Claim 17

An electronic flash unit, comprising first and second input terminals adapted to be energized with a DC voltage when an illuminating flash is to be produced, a third terminal, a resistor having a resistance approximating the impedance of an unfired flashlamp connected between said first terminal and said third terminal, a capacitor connected between said second terminal and said third terminal, a light-emitting diode, means connecting said light-emitting diode between said first terminal and said third terminal to produce a flash of light upon the application of a DC voltage to said first and second terminals, a flash circuit comprising a triggerable gas discharge tube, means for supplying energy to said discharge tube to cause said tube to emit an illuminating flash of light when triggered, and circuit means comprising a light-responsive switch confronting said light-emitting diode for triggering said flash circuit when a flash of light is emitted by said light-emitting diode.

Claim 18

An accessory electronic flash unit for a camera adapted for use with flashlamps and having a pair of output terminals to which a DC voltage is applied when a flashlamp is to be fired and means responsive to the impedance increase across the output terminals when a flashlamp is fired for initiating the termination of an exposure cycle, said flash unit comprising rechargeable flash circuit means having first and second input terminals, said flash circuit means comprising means for producing a voltage across said input terminals when said flash circuit means is charged, light-responsive switching means connected between said first and second input terminals and responsive to an applied light flash to allow the flow of current between said first and second terminals when said voltage is present, and means responsive to the flow of current between said terminals for producing an illuminating flash of light, and coupling circuit, said coupling circuit comprising third and fourth input terminals adapted to be connected to the output terminals of the camera to receive a DC voltage when an illuminating flash is required, a resistor and a capacitor connected in series with said third and fourth terminls to simulate a flashlamp by drawing a pulse of current when a DC voltage is applied to said third and fourth terminals, and light-emitting impedance means confronting said light-responsive switch and connected in parallel with said resistor to produce a flash of light when a pulse of current flows between said third and fourth terminals and thereby apply a light flash to said light-responsive switch.

Claim 19

An accessory electronic flash unit for a camera adapted for use with flashlamps and having a pair of output terminals to which a DC voltage is applied when a flashlamp is to be fired and means responsive to the impedance increase across the output terminals when a flashlamp is fired for initiating the termination of an exposure cycle, said flash unit comprising rechargeable flash circuit means having first and second input terminals, said flash circuit means comprising means for producing a voltage across said input terminals when said flash circuit means is charged, light-responsive switching means connected between said first and second input terminals and responsive to an applied light flash to allow the flow of current between said first and second terminals when said voltage is present, and means responsive to the flow of current between said terminals for producing an illuminating flash of light, and coupling circuit, said coupling circuit comprising third and fourth input terminals adapted to be connected to the output terminals of the camera to receive a DC voltage when an illuminating flash is required, a resistor and a capacitor connected in series with said third and fourth terminls to simulate a flashlamp by drawing a pulse of current when a DC voltage is applied to said third and fourth terminals, and light-emitting impedance means confronting said light-responsive switch and connected in parallel with said resistor to produce a flash of light when a pulse of current flows between said third and fourth terminals and thereby apply a light flash to said light-responsive switch.

Claim 20

Apparatus for use with a camera having an accessory connector adapted to receive at least one flashlamp and having terminals adapted to be supplied with current for firing a flashlamp, said apparatus comprising means for mounting a triggerable gas discharge tube, means for supplying electrical energy to the tube to cause the tube to produce a flash of light when triggered, trigger circuit means adapted to be connected to the tube and responsive to an applied signal to trigger the tube, and a signal generating impedance netwoRk having input terminals adapted to be connected to the current supply terminals of the camera, said network comprising a resistance approximating the resistance of an unfired flashlamp connected in series with a capacitor between said input terminals, whereby current supplied to said input terminals flows in a pulse that falls in amplitude as said capacitor is charged, simulating the impedance characteristics of a flashlamp as it is fired, said impedance network further comprising means responsive to the flow of current through said capacitor to apply a signal to said trigger circuit means.

Claim 21

Apparatus for use with a camera having an accessory connector adapted to receive at least one flashlamp and having terminals adapted to be supplied with current for firing a flashlamp, said apparatus comprising means for mounting a triggerable gas discharge tube, means for supplying electrical energy to the tube to cause the tube to produce a flash of light when triggered, trigger circuit means adapted to be connected to the tube and responsive to an applied signal to trigger the tube, and a signal generating impedance netwoRk having input terminals adapted to be connected to the current supply terminals of the camera, said network comprising a resistance approximating the resistance of an unfired flashlamp connected in series with a capacitor between said input terminals, whereby current supplied to said input terminals flows in a pulse that falls in amplitude as said capacitor is charged, simulating the impedance characteristics of a flashlamp as it is fired, said impedance network further comprising means responsive to the flow of current through said capacitor to apply a signal to said trigger circuit means.

Claim 22

A photoelectrical trigger and flashlamp simulating circuit for optically triggering an electronic flash unit having a photoresponsive trigger circuit in responsive to a voltage appearing on a pair of flash firing terminals on a camera, comprising a pair of input terminals adapted to be connected to the flash firing terminals of the camera, a capacitor and a first resistor having a resistance approximating the resistance of a unfired flashlamp connected in series between said terminals, whereby an impedance simulating that of a flashlamp being fired is presented across said input terminals when a voltage is applied to said input terminals with said capacitor initially discharged, a light-emitting diode and a second resistor connected in series across said first resistor, whereby an optical triggering light flash is produced by said light-emitting diode when a voltage is applied to said input terminals, and a third resistor having a resistance high enough to simulate an open circuit connected across said capacitor whereby said capacitor is discharged when it has been charged by a voltage applied to said input terminals and the voltage is subsequently removed.

Claim 23

A photoelectrical trigger and flashlamp simulating circuit for optically triggering an electronic flash unit having a photoresponsive trigger circuit in responsive to a voltage appearing on a pair of flash firing terminals on a camera, comprising a pair of input terminals adapted to be connected to the flash firing terminals of the camera, a capacitor and a first resistor having a resistance approximating the resistance of a unfired flashlamp connected in series between said terminals, whereby an impedance simulating that of a flashlamp being fired is presented across said input terminals when a voltage is applied to said input terminals with said capacitor initially discharged, a light-emitting diode and a second resistor connected in series across said first resistor, whereby an optical triggering light flash is produced by said light-emitting diode when a voltage is applied to said input terminals, and a third resistor having a resistance high enough to simulate an open circuit connected across said capacitor whereby said capacitor is discharged when it has been charged by a voltage applied to said input terminals and the voltage is subsequently removed.

Claim 24

Apparatus for triggering an electronic flash unit having a main flash lamp and a trigger circuit including a photosensitive device responsive to a flash of light to trigger the main flash lamp, comprising an impedance network whose impedance varies from low to high in response to an applied voltage to simulate the impedance of a flash lamp before and during firing, said impedance network comprising a light-emitting element for applying a flash of light to the photosensitive device in response to the application of a voltage to said network.

Claim 25

Apparatus for triggering an electronic flash unit having a main flash lamp and a trigger circuit including a photosensitive device responsive to a flash of light to trigger the main flash lamp, comprising an impedance network whose impedance varies from low to high in response to an applied voltage to simulate the impedance of a flash lamp before and during firing, said impedance network comprising a light-emitting element for applying a flash of light to the photosensitive device in response to the application of a voltage to said network.

Claim 26

The apparatus of claim 13 in which said impedance network is connected between a pair of terminals adapted to be connected to flash firing terminals of a camera across which a voltage suitable for firing a flashlamp is applied when an illuminating flash is required, said network comprising a first resistor having a resistance approximating the resistance of an unfired flashlamp and a capacitor connected in series between said terminals, means connecting said light-emitting element in parallel with said first resistor, and a second resistor having a resistance simulating the impedance of a fired flashlamp connected in parallel with said capacitor to discharge said capacitor in the absence of a voltage applied to said terminals.