Electronic flash device with automatic light control

Claim 2

A flashlight discharge lamp control system comprising: a DC power source; a main discharge capacitor; a first series circuit comprising a plurality of charging resistors and a trigger capacitor; a second series circuit comprising a flashlight discharge tube and a first control element; said main discharge capacitor and said first and second series circuits being connected in parallel with said DC power source; means applying a trigger pulse to a trigger electrode of said flashlight discharge tube from said trigger capacitor through a Switch, including a trigger transformer connected in parallel with said trigger capacitor; means connecting a gate electrode of said first control element to the junction point of said charging resistors, wherein a voltage developed at said junction point is applied to said gate electrode concurrent with the application of said trigger pulse to said trigger electrode; a third series circuit comprising a control capacitor and second control element, said third series circuit being connected in parallel with said first control element; a charging circuit comprising a resistor and a diode for charging said control capacitor from said DC power source, said resistor being connected between one terminal of said DC power source and the junction of said control capacitor and said second control element, and said diode being connected between the electrode of said control capacitor opposite to that connected to said second control element and the other terminal of said power source to hold a charge on said control capacitor when said first control element is non-conductive and said second control element is conductive; and a light receiving circuit for sensing the light reflected from an object and for providing a control voltage corresponding to an integrated value of the amount of reflected light, said light receiving circuit connected to said second control element to apply to the gate electrode thereof the output control voltage and comprising a light sensitive element, a capacitor and a resistor, connected in parallel with each other, wherein when the control voltage reaches a predetermined level and hence said second control element is rendered conductive, said control capacitor discharges through the second control element to thereby allow a current flow through said first control element in the reverse direction.

Claim 3

A flashlight discharge lamp control system according to claim 1, wherein the resistor in said light receiving circuit comprises a variable resistor to adjust the gating time of said second control element.

Claim 4

A flashlight discharge lamp control system comprising: a DC power source; a main discharge capacitor; a first series circuit comprising a plurality of charging resistors and a trigger capacitor; a second series circuit comprising a flashlight discharge tube and a first control element; said main discharge capacitor and said first and second series circuits being connected in parallel with said DC power source; means applying a trigger pulse to a trigger electrode of said flashlight discharge tube from said trigger capacitor through a switch, including a trigger transformer connected in parallel with said trigger capacitor; means connecting a gate electrode of said first control element to the junction point of said charging resistors, wherein a voltage developed at said junction point is applied to said gate electrode concurrent with the application of said trigger pulse to said trigger electrode; a third series circuit comprising a control capacitor, second control element and a secondary winding of a pulse transformer, said third series circuit being connected in parallel with said first control element; a charging circuit comprising a resistor and a diode for charging said control capacitor from said DC power source, said resistor being connected between one terminal of said DC power source and the junction of said control capacitor and said second control element, and said diode being connected between the electrode of said control capacitor opposite to that connected to said second control element and the other terminal of said power source; a fourth series circuit comprising a primary winding of said pulse transformer, a further capacitor and a resistor, said fourth series circuit being connected across said DC power source; a third control element connected across the series circuit of said primary winding of said pulse transformer and said further capacitor; and a light receiving circuit for sensing the light reflected from an object and For providing a control voltage corresponding to an integrated value of the amount of reflected light, and light receiving circuit connect to said third control element to apply to the gate electrode thereof the output control voltage and comprising a light sensitive element, a capacitor and a resistor, connected in parallel with each other, wherein when the control voltage reaches a predetermined level and hence said third control element is rendered conductive, said control capacitor discharges through the second control element to thereby allow a current to flow through said first control element in the reverse direction.

Claim 5

A flashlight discharge lamp control system comprising: a DC power source; a main discharge capacitor; a first series circuit comprising a plurality of charging resistors and a trigger capacitor; a second series circuit comprising a flashlight discharge tube and a first control element; said main discharge capacitor and said first and second series circuits being connected in parallel with said DC power source; means applying a trigger pulse to a trigger electrode of said flashlight discharge tube from said trigger capacitor through a switch, including a trigger transformer connected in parallel with said trigger capacitor; means connecting a gate electrode of said first control element to the junction point of said charging resistors, wherein a voltage developed at said junction point is applied to said gate electrode concurrent with the application of said trigger pulse to said trigger electrode; a third series circuit comprising a control capacitor, second control element and a secondary winding of a pulse transformer, said third series circuit being connected in parallel with said first control element; a charging circuit comprising a resistor and a diode for charging said control capacitor from said DC power source, said resistor being connected between one terminal of said DC power source and the junction of said control capacitor and said second control element, and said diode being connected between the electrode of said control capacitor opposite to that connected to said second control element and the other terminal of said power source; a fourth series circuit comprising a primary winding of said pulse transformer, a further capacitor and a resistor, said fourth series circuit being connected across said DC power source; a third control element connected across the series circuit of said primary winding of said pulse transformer and said further capacitor; and a light receiving circuit for sensing the light reflected from an object and For providing a control voltage corresponding to an integrated value of the amount of reflected light, and light receiving circuit connect to said third control element to apply to the gate electrode thereof the output control voltage and comprising a light sensitive element, a capacitor and a resistor, connected in parallel with each other, wherein when the control voltage reaches a predetermined level and hence said third control element is rendered conductive, said control capacitor discharges through the second control element to thereby allow a current to flow through said first control element in the reverse direction.

Claim 6

A flashlight discharge control system comprising: a DC power source; a main discharge capacitor; a first series circuit comprising a plurality of charging resistors and a trigger capacitor; a second series circuit comprising a flashlight discharge tube and a first control element; said main discharge capacitor and said first and second series circuits being connected in parallel with said DC power source; means applying a trigger pulse to a trigger electrode of said flashlight discharge tube from said trigger capacitor through a switch, including a trigger transformer connected in parallel with said trigger capacitor; means connecting a gate electrode of said first control element to the junction point of said charging resistors, wherein a voltage developed at said junction point is applied to said gate electrode concurrent with the application of said trigger pulse to said trigger electrode; a third series circuit comprising a control capacitor and second control element, said third series circuit being connected in parallel with said first control element; a charging circuit comprising a resistor and a diode for charging said control capacitor from said DC power source, said resistor being connected between one terminal of said DC power source and the junction of said control capacitor and said second control element, and said diode being connected between the electrode of said control capacitor opposite to that connected to said second control element and the other terminal of said power source to hold a charge on said control capacitor when said first control element is non-conductive and said second control element is conductive; and a light receiving circuit connected between the gate electrode and another electrode of said second control element; wherein said light receiving circuit comprises a further capacitor and a photoconductive element connected in parallel with each other between the gate and the cathode electrodes of said second control element, said photoconductive element is further connected to the DC power source through a further resistor, and a still further capacitor and a voltage regulator diode are connected in parallel with the series circuit comprising said photoconductive element and said further resistor, and wherein when said second control element is rendered conductive, said control capacitor discharges through the second control element to thereby allow a current to flow through said first control element in the reverse direction.

Claim 7

A flashlight discharge control system comprising: a DC power source; a main discharge capacitor; a first series circuit comprising a plurality of charging resistors and a trigger capacitor; a second series circuit comprising a flashlight discharge tube and a first control element; said main discharge capacitor and said first and second series circuits being connected in parallel with said DC power source; means applying a trigger pulse to a trigger electrode of said flashlight discharge tube from said trigger capacitor through a switch, including a trigger transformer connected in parallel with said trigger capacitor; means connecting a gate electrode of said first control element to the junction point of said charging resistors, wherein a voltage developed at said junction point is applied to said gate electrode concurrent with the application of said trigger pulse to said trigger electrode; a third series circuit comprising a control capacitor and second control element, said third series circuit being connected in parallel with said first control element; a charging circuit comprising a resistor and a diode for charging said control capacitor from said DC power source, said resistor being connected between one terminal of said DC power source and the junction of said control capacitor and said second control element, and said diode being connected between the electrode of said control capacitor opposite to that connected to said second control element and the other terminal of said power source to hold a charge on said control capacitor when said first control element is non-conductive and said second control element is conductive; and a light receiving circuit connected between the gate electrode and another electrode of said second control element; wherein said light receiving circuit comprises a further capacitor and a photoconductive element connected in parallel with each other between the gate and the cathode electrodes of said second control element, said photoconductive element is further connected to the DC power source through a further resistor, and a still further capacitor and a voltage regulator diode are connected in parallel with the series circuit comprising said photoconductive element and said further resistor, and wherein when said second control element is rendered conductive, said control capacitor discharges through the second control element to thereby allow a current to flow through said first control element in the reverse direction.

Claim 8

A flashlight discharge lamp control system comprising: a DC power source; a main discharge capacitor connected across said DC power source; a discharge circuit comprising a serially connected flashlight discharge lamp and a first control element, said discharge circuit being connected across said power source; means for simultaneously triggering said flashlight discharge lamp and said first control element, said simultaneous trigger means comprising a series circuit of a trigger means comprising a series circuit of a trigger capacitor and voltage dividing resistors connected across said main discharge capacitor and further comprising a trigger transformer having a primary winding connected across said trigger capacitor through a switch, the output terminal of said voltage dividing resistors being connected to the gate of said first control element, thereby upon contactinG the switch the trigger capacitor discharges through the primary winding to produve a high trigger voltage in the secondary winding of the trigger transformer and at the same time a divided voltage of said main discharge capacitor is developed in the voltage dividing resistors to render said first control element conductive; light receiving circuit means for sensing the light reflected from an object and for providing a control voltage signal corresponding to an integrated value of the amount of reflected light; a control circuit comprising a serially connected second control element and a control capacitor connected for charging from said power source; means applying said control voltage signal from said light receiving circuit means to control conduction of said second control element, said second control element being rendered conductive upon said control voltage signal reaching a predetermined value; means to discharge said control capacitor upon conduction of said second control element, wherein discharge current from said discharge circuit flows through said first control element in a reverse direction with respect to its normal conduction thereby resulting in termination of the discharge of said discharge lamp.

Claim 9

A flashlight discharge lamp control system comprising: a DC power source; a main discharge capacitor connected across said DC power source; a discharge circuit comprising a serially connected flashlight discharge lamp and a first control element, said discharge circuit being connected across said power source; means for simultaneously triggering said flashlight discharge lamp and said first control element, said simultaneous trigger means comprising a series circuit of a trigger means comprising a series circuit of a trigger capacitor and voltage dividing resistors connected across said main discharge capacitor and further comprising a trigger transformer having a primary winding connected across said trigger capacitor through a switch, the output terminal of said voltage dividing resistors being connected to the gate of said first control element, thereby upon contactinG the switch the trigger capacitor discharges through the primary winding to produve a high trigger voltage in the secondary winding of the trigger transformer and at the same time a divided voltage of said main discharge capacitor is developed in the voltage dividing resistors to render said first control element conductive; light receiving circuit means for sensing the light reflected from an object and for providing a control voltage signal corresponding to an integrated value of the amount of reflected light; a control circuit comprising a serially connected second control element and a control capacitor connected for charging from said power source; means applying said control voltage signal from said light receiving circuit means to control conduction of said second control element, said second control element being rendered conductive upon said control voltage signal reaching a predetermined value; means to discharge said control capacitor upon conduction of said second control element, wherein discharge current from said discharge circuit flows through said first control element in a reverse direction with respect to its normal conduction thereby resulting in termination of the discharge of said discharge lamp.