Automatic photoflash devices

Claim 2

An automatic electronic photoflash comprising, in combination: an electronic photoflash tube having two main electrodes and a trigger electrode; a trigger circuit connected to said trigger electrode for applying a flash initiation pulse thereto; a first normally open electronic switch connected in series with said tube; an energy storage capacitor connected in series with said tube and first switch; a flash initiation circuit connected to said trigger circuit and to said first switch for causing said trigger circuit to produce a flash initiation pulse and for closing said first switch when a light flash is to be produced; a flash limiting circuit for producing a signal when a light flash being produced by said tube is to be terminated; a second normally open electronic switch connected tO said flash limiting circuit to be closed in response to a signal therefrom; a normally charged second capacitor connected in series with said second switch; and means connecting said second switch and said second capacitor in parallel with the series arrangement of said tube and said first switch for enabling the closing of said second switch to convert the charge on said second capacitor into a current flow through said tube in a direction opposite to the direction of current flow from said storage capacitor to said tube and of an amplitude sufficient to open said first switch, thereby to abruptly terminate the light flash being produced by said tube.

Claim 3

An arrangement as defined in claim 1, further comprising voltage source means connected with said second capacitor for preliminarily charging said second capacitor to a predetermined voltage.

Claim 4

An arrangement as defined in claim 1 wherein each of said switches is constituted by a thyristor, said flash initiation circuit being connected to the gate electrode of said first switch thyristor and said flash limiting trigger circuit being connected to the gate electrode of said second switch thyristor.

Claim 5

An arrangement as defined in claim 1 wherein at least one of said switches is constituted by a gas-filled discharge tube having two main electrodes and a trigger electrode.

Claim 6

An arrangement as defined in claim 4 wherein said discharge tube is filled with gas having low atomic weight.

Claim 7

An arrangement as defined in claim 5 wherein the gas is hydrogen.

Claim 8

An arrangement as defined in claim 6 wherein said discharge tube is a triastor.

Claim 9

An arrangement as defined in claim 1, further comprising: means for charging said energy storage capacitor and said second capacitor effectively in parallel to respective predetermined voltages preparatory to the initiation of a light flash.

Claim 10

An arrangement as defined in claim 8, further comprising an indicator circuit connected across said second capacitor for providing an indication that said photoflash is ready for use.

Claim 11

An arrangement as defined in claim 9 wherein said indication circuit comprises: a potentiometer having its resistance connected across said second capacitor; and an indicator lamp connected between one end of the resistance of said potentiometer and the movable tap of said potentiometer.

Claim 12

In an automatic electronic photoflash device including an electronic photoflash tube, energy supply means for supplying current to the tube when a light flash is to be produced, means connected to the tube for producing a signal which initiates the production of such a light flash, and automatic flash limiting means including a light sensor and arranged to produce a signal terminating a light flash when a predetermined quantity of light has been received by the sensor, the improvement wherein said flash limiting means comprise: first, normally open, electronic switch means connected in parallel with said tube and connected to be closed upon the appearange of a signal from said flash limiting means for short-circuiting said tube and thus terminating its light flash; and second, normally closed, electronic switch means connected in series between said energy supply means and the parallel arrangement of said tube and said first switch means and arranged to open upon the closing of said first switch means for blocking the flow of current from said energy supply means to both said tube and said first switch.

Claim 13

In an automatic electronic photoflash device including an electronic photoflash tube, energy supply means for supplying current to the tube when a light flash is to be produced, means connected to the tube for producing a signal which initiates the production of such a light flash, and automatic flash limiting means including a light sensor and arranged to produce a signal terminating a light flash when a predetermined quantity of light has been received by the sensor, the improvement wherein said flash limiting means comprise: first, normally open, electronic switch means connected in parallel with said tube and connected to be closed upon the appearange of a signal from said flash limiting means for short-circuiting said tube and thus terminating its light flash; and second, normally closed, electronic switch means connected in series between said energy supply means and the parallel arrangement of said tube and said first switch means and arranged to open upon the closing of said first switch means for blocking the flow of current from said energy supply means to both said tube and said first switch.

Claim 14

An arrangement as defined in claim 11 wherein said energy supply means comprise a storage capacitor connected in series with said tube and said second switch means.

Claim 15

An arrangement as defined in claim 12 wherein said second switch means is connected to be opened upon the appearance of a signal from said flash limiting means.

Claim 16

An arrangement as defined in claim 13 wherein said second switch means comprise: a fast-acting relay including a normally closed contact connected in series between said capacitor and said tube and a coil for controlling the opening of said contact; and a semiconductor control element connected in series with said coil and connected to be operated by a signal from said flash limiting means for opening said relay contact.

Claim 17

An arrangement as defined in claim 12 wherein said second switch means are disposed in series between said capacitor and said first switch means and arranged to open in response to the short circuit current created by the closing of said first switch means.

Claim 18

An arrangement as defined in claim 15 wherein said second switch comprises: a pair of electrically conductive contacts, and at least one coil of a mechanically resilient, electrically conductive material connected to and supporting one of said contacts and formed as a compression spring normally urging said one of said contacts against the other one of said contacts, said coil and said contacts being connected to conduct the current flowing from said capacitor, and said coil being formed to act as a solenoid attracting said one contact with a force proportional to the current flowing therethrough and to produce a mechanical spring force of a value such that it is overcome by the electromagnetic attraction force produced by the short circuit current occurring when said first switch closes, whereupon said one contact is drawn away from said other contact.

Claim 19

An arrangement as defined in claim 16 wherein there are two of said coils each connected to and supporting a respective one of said contacts and each arranged to subject its respective contact to an electromagnetic attraction force.

Claim 20

An arrangement as defined in claim 17 wherein said second switch further comprises a hermetically sealed casing enclosing said contacts and said coils.

Claim 21

An arrangement as defined in claim 16 wherein said second switch further comprises a capacitor connected between said contacts.

Claim 22

An arrangement as defined in claim 15 wherein said second switch comprises: a pair of conductive contacts; spring means normally urging said contacts together; and at least one solenoid coil connected in series with said contacts and arranged to conduct the current from said capacitor and to produce an electromagnetic force attracting its said contact, this force exceeding the force produced by said spring means upon the occurrence of the short circuit current appearing when said first switch closes.

Claim 25

An arrangement as defined in claim 21, further comprising manually operable switch means connected for activating said pulse counting means.

Claim 26

An arrangement as defined in claim 22 wherein said load is an electronic photoflash tube, said sensing means is a light sensor also responsive to ambient light, said switch means is a camera synchronization contact, and said logic control means are connected for activating said counting means upon closing of said switch means and for initiating the delivery of light flash producing energy to said tube upon response of said counting means to a pulse from said converter after closing of said switch means.

Claim 27

In an automatic photoflash device including a photoflash tube, means connected for triggering the tube into its conductive state, when operating power is applied to the tube, a power source for supPlying power for the device, and a light sensing circuit arranged for sensing the light reflected from a subject illuminated by the light produced by the tube and for producing an output signal upon receipt of a predetermined quantity of light exceeding a value corresponding to a predetermined minimum quantity of light produced by the tube, the improvement comprising: pulse generating means connected in series between the power source and the tube for generating, and applying to the tube, a train of electrical pulses constituting the tube operating power upon the tube being triggered into its conductive state, each pulse produced by said means resulting in the production of less than the predetermined minimum quantity of light; and means connecting the light sensing circuit to said pulse generating means for causing the occurrence of the light sensing means output signal to prevent the generation of subsequent pulses by said generating means.

Claim 28

In an automatic photoflash device including a photoflash tube, means connected for triggering the tube into its conductive state, when operating power is applied to the tube, a power source for supPlying power for the device, and a light sensing circuit arranged for sensing the light reflected from a subject illuminated by the light produced by the tube and for producing an output signal upon receipt of a predetermined quantity of light exceeding a value corresponding to a predetermined minimum quantity of light produced by the tube, the improvement comprising: pulse generating means connected in series between the power source and the tube for generating, and applying to the tube, a train of electrical pulses constituting the tube operating power upon the tube being triggered into its conductive state, each pulse produced by said means resulting in the production of less than the predetermined minimum quantity of light; and means connecting the light sensing circuit to said pulse generating means for causing the occurrence of the light sensing means output signal to prevent the generation of subsequent pulses by said generating means.

Claim 29

An arrangement as defined in claim 24 wherein successive pulses produced by said generating means are spaced from one another by a time interval no greater than the time required for the tube to deionize upon termination of the delivery of light flash producing energy thereto.

Claim 30

An arrangement as defined in claim 24 further comprising means connected between said generating means and the light sensing circuit for causing the pulses produced by said generating means to supply energizing power to the light sensing circuit.

Claim 31

An arrangement as defined in claim 24 wherein said pulse generating means are arranged to begin generating such train of pulses in response to the application of a triggering signal to the tube by the triggering means.

Claim 32

An arrangement as defined in claim 1 further comprising a current-limiting induction coil connected in series between said energy storage capacitor and one main electrode of said tube for limiting the amplitude of the current from said energy storage capacitor during the turn-on of said electronic switches.

Claim 33

An automatic electronic photoflash comprising, in combination: an electronic photoflash tube; an energy storage source; a first electronic switch which is closed when said photoflash tube is producing light, and means connecting said source and switch in series; trigger means coupled with said photoflash tube for firing said tube; a flash initiation circuit connected to said trigger means and to said first switch for causing firing of said tube and closing of said first switch when a light flash is to be produced by said tube; a flash limiting circuit for producing a signal when a light flash being produced by said tube is to be terminated; said flash limiting circuit including a light sensor arranged to produce a terminating signal when a predetermined quantity of light resulting from light from said tube has been received by said sensor; said flash limiting circuit including a second normally open electronic switch adapted to be closed when said light flash is to be terminated, and means connecting said second electronic switch in parallel with said tube; and means connecting said first switch and source in series with the parallel combination of said tube and second switch.

Claim 34

An automatic electronic photoflash comprising, in combination: an electronic photoflash tube; an energy storage source; a first electronic switch which is closed when said photoflash tube is producing light, and means connecting said source and switch in series; trigger means coupled with said photoflash tube for firing said tube; a flash initiation circuit connected to said trigger means and to said first switch for causing firing of said tube and closing of said first switch when a light flash is to be produced by said tube; a flash limiting circuit for producing a signal when a light flash being produced by said tube is to be terminated; said flash limiting circuit including a light sensor arranged to produce a terminating signal when a predetermined quantity of light resulting from light from said tube has been received by said sensor; said flash limiting circuit including a second normally open electronic switch adapted to be closed when said light flash is to be terminated, and means connecting said second electronic switch in parallel with said tube; and means connecting said first switch and source in series with the parallel combination of said tube and second switch.

Claim 35

An automatic electronic photoflash comprising, in combination: an electronic photoflash tube having two main electrodes and a trigger electrode; a trigger circuit connected to said trigger electrode for applying a flash initiation pulse thereto; a first normally open electronic switch connected in series with said tube; an energy storage capacitor connected in series with said tube and first switch; a flash initiation circuit connected to said trigger circuit and to said first switch for causing said trigger circuit to produce a flash initiation pulse and for closing said first switch when a light flash is to be produced; a second normally open electronic switch; a second capacitor; means connecting Said second switch and said second capacitor in series; means connecting the series combination of said second switch and said second capacitor in parallel with the series arrangement of said tube and said first switch; a flash limiting circuit responsive to a predetermined amount of light reflected from a subject illuminated by a light flash from said tube for producing a signal when the light flash being produced by said tube is to be terminated; and means connecting said flash limiting circuit with said second switch for causing said second switch to be closed in response to the signal from said flash limiting circuit.

Claim 36

An automatic electronic photoflash comprising, in combination: an electronic photoflash tube having two main electrodes and a trigger electrode; a trigger circuit connected to said trigger electrode for applying a flash initiation pulse thereto; a first normally open electronic switch connected in series with said tube; an energy storage capacitor connected in series with said tube and first switch; a flash initiation circuit connected to said trigger circuit and to said first switch for causing said trigger circuit to produce a flash initiation pulse and for closing said first switch when a light flash is to be produced; a second normally open electronic switch; a second capacitor; means connecting Said second switch and said second capacitor in series; means connecting the series combination of said second switch and said second capacitor in parallel with the series arrangement of said tube and said first switch; a flash limiting circuit responsive to a predetermined amount of light reflected from a subject illuminated by a light flash from said tube for producing a signal when the light flash being produced by said tube is to be terminated; and means connecting said flash limiting circuit with said second switch for causing said second switch to be closed in response to the signal from said flash limiting circuit.

Claim 37

An automatic electronic photoflash comprising, in combination: an electronic photoflash tube; an energy storage source; a first electronic switch which is closed when said photoflash tube is producing light, and means connecting said source and switch in series; flash initiation means for causing firing of said tube and closing of said first switch when a light flash is to be produced by said tube, said flash initiation means including trigger means coupled with said tube for firing the tube in response to a control signal applied thereto; a flash limiting circuit for producing a signal when a light flash being produced by said tube is to be terminated; said flash limiting circuit including a light sensor arranged to produce a terminating signal when a predetermined quantity of light resulting from light from said tube has been received by said sensor; said flash limiting circuit including a second normally open electronic switch adapted to be closed when said light flash is to be terminated, and means connecting said second electronic switch in parallel with said tube; and means connecting said first switch and source in series with the parallel combination of said tube and second switch.

Claim 38

An automatic electronic photoflash comprising, in combination: an electronic photoflash tube; an energy storage source; a first electronic switch which is closed when said photoflash tube is producing light, and means connecting said source and switch in series; flash initiation means for causing firing of said tube and closing of said first switch when a light flash is to be produced by said tube, said flash initiation means including trigger means coupled with said tube for firing the tube in response to a control signal applied thereto; a flash limiting circuit for producing a signal when a light flash being produced by said tube is to be terminated; said flash limiting circuit including a light sensor arranged to produce a terminating signal when a predetermined quantity of light resulting from light from said tube has been received by said sensor; said flash limiting circuit including a second normally open electronic switch adapted to be closed when said light flash is to be terminated, and means connecting said second electronic switch in parallel with said tube; and means connecting said first switch and source in series with the parallel combination of said tube and second switch.

Claim 39

An automatic electronic photoflash comprising, in combination: an electronic photoflash tube having two main electrodes and a trigger electrode; a first normally open electronic switch connected in series with said tube; an energy storage capacitor connected in series with said tube and said first switch; flash initiation means for causing firing of said tube and closing of said first switch when a light flash is to be produced by said tube, said flash initiation means including trigger means coupled with said tube for firing the tube in response to a control signal applied thereto and including means for closing said first switch; a second normally open electronic switch; a second capacitor; means connecting said second switch and said second capacitor in series; means connecting the series combination of said second switch and said second capacitor in parallel with the series arrangement of said tube and said first switch; a third capacitor, means connecting said third capacitor from the junction between said second capacitor and said second switch to the junction between said flash tube and said first switch; a flash limiting circuit responsive to a predetermined amount of light reflected from a subject illuminated by a light flash from said tube for producing a signal when the light flash being produced by said tube is to be terminated; and means connecting said flash limiting circuit with said second switch for causing said second switch to be closed in response to the signal from said flash limiting circuit.

Claim 40

An automatic electronic photoflash comprising, in combination: an electronic photoflash tube having two main electrodes and a trigger electrode; a first normally open electronic switch connected in series with said tube; an energy storage capacitor connected in series with said tube and said first switch; flash initiation means for causing firing of said tube and closing of said first switch when a light flash is to be produced by said tube, said flash initiation means including trigger means coupled with said tube for firing the tube in response to a control signal applied thereto and including means for closing said first switch; a second normally open electronic switch; a second capacitor; means connecting said second switch and said second capacitor in series; means connecting the series combination of said second switch and said second capacitor in parallel with the series arrangement of said tube and said first switch; a third capacitor, means connecting said third capacitor from the junction between said second capacitor and said second switch to the junction between said flash tube and said first switch; a flash limiting circuit responsive to a predetermined amount of light reflected from a subject illuminated by a light flash from said tube for producing a signal when the light flash being produced by said tube is to be terminated; and means connecting said flash limiting circuit with said second switch for causing said second switch to be closed in response to the signal from said flash limiting circuit.