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US 6,147,460 AGranted
Flash apparatus
AssigneeCanon Kabushiki Kaisha
InventorYoshiro Ichihara
Life of this patent
Estimating the term…
Abstract
In a power supply device for a flash apparatus having the primary winding side of a transformer and an oscillation-controlling switching element connected in parallel to a power supply and the secondary winding side of the transformer connected to a main capacitor through a rectifier element, a current-to-voltage conversion circuit is arranged to output a voltage signal according to a current flowing from the secondary winding side of the transformer to the main capacitor, and the main capacitor is charged by on-off controlling the switching element according to the voltage signal outputted from the current-to-voltage conversion circuit.
Claims24
A flash apparatus comprising:
- a transformer;
- a switching element connected in series to a primary coil of said transformer, said switching element being turned on to cause a current from a power supply to flow to the primary coil and being turned off to cut off the current to the primary coil;
- current-to-voltage conversion means connected to a secondary coil of said transformer for forming a voltage according to a value of a current flowing to the secondary coil;
- and
- a signal forming circuit which detects the voltage formed by said current-to-voltage conversion means and shifts an output state thereof from a first signal output state to a second signal output state when having detected that the voltage indicates a voltage value representing that the value of the current flowing to the secondary coil is less than a predetermined value,
- wherein said switching element is connected to said signal forming circuit and is arranged to be turned on when the output state of said signal forming circuit is the first signal output state and to be turned off when the output state of said signal forming circuit is the second signal output state.
3 more elements
A flash apparatus comprising:
- a transformer;
- a switching element connected in series to a primary coil of said transformer, said switching element being turned on to cause a current from a power supply to flow to the primary coil and being turned off to cut off the current to the primary coil;
- a current-to-voltage conversion circuit having a transistor and an impedance element, a base of said transistor being connected to a secondary coil of said transformer so that a base current according to a value of a current flowing to the secondary coil flows, a collector of said transistor being connected to said impedance element, said transistor forming, as an output of said impedance element, a voltage according to the value of the current flowing to the secondary coil;
- and
- a signal forming circuit which detects the voltage formed by said current-to-voltage conversion circuit and shifts an output state thereof from a first signal output state to a second signal output state when having detected that the voltage indicates a voltage value representing that the value of the current flowing to the secondary coil is less than a predetermined value,
- wherein said switching element is connected to said signal forming circuit and is arranged to be turned on when the output state of said signal forming circuit is the first signal output state and to be turned off when the output state of said signal forming circuit is the second signal output state.
3 more elements
A DC-to-DC converter device for a flash apparatus, comprising:
- a transformer;
- a switching element connected in series to a primary coil of said transformer, said switching element being turned on to cause a current from a power supply to flow to the primary coil and being turned off to cut off the current to the primary coil;
- current-to-voltage conversion means connected to a secondary coil of said transformer for forming a voltage according to a value of a current flowing to the secondary coil;
- and
- a signal forming circuit which detects the voltage formed by said current-to-voltage conversion means and shifts an output state thereof from a first signal output state to a second signal output state when having detected that the voltage indicates a voltage value representing that the value of the current flowing to the secondary coil is less than a predetermined value,
- wherein said switching element is connected to said signal forming circuit and is arranged to be turned on when the output state of said signal forming circuit is the first signal output state and to be turned off when the output state of said signal forming circuit is the second signal output state.
3 more elements
A DC-to-DC converter device for a flash apparatus, comprising:
- a transformer;
- a switching element connected in series to a primary coil of said transformer, said switching element being turned on to cause a current from a power supply to flow to the primary coil and being turned off to cut off the current to the primary coil;
- a current-to-voltage conversion circuit having a transistor and an impedance element, a base of said transistor being connected to a secondary coil of said transformer so that a base current according to a value of a current flowing to the secondary coil flows, a collector of said transistor being connected to said impedance element, said transistor forming, as an output of said impedance element, a voltage according to the value of the current flowing to the secondary coil;
- and
- a signal forming circuit which detects the voltage formed by said current-to-voltage conversion circuit and shifts an output state thereof from a first signal output state to a second signal output state when having detected that the voltage indicates a voltage value representing that the value of the current flowing to the secondary coil is less than a predetermined value,
- wherein said switching element is connected to said signal forming circuit and is arranged to be turned on when the output state of said signal forming circuit is the first signal output state and to be turned off when the output state of said signal forming circuit is the second signal output state.
3 more elements
Dependencies are inferred from the claim text.