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US 4,233,659 AGranted
Defibrillator charging current regulator
AssigneeHewlett-Packard Company
InventorSherman J. Pirkle
Life of this patent
Estimating the term…
Abstract
The capacitor of a defibrillator is charged to a high D.C. voltage from a low voltage D.C. source of small capacity by an inverter, a transformer, and a rectifier coupled in sequence. The turns ratio of the transformer is changed as the voltage across the capacitor reaches predetermined levels and the current in the primary of the transformer is regulated by comparing the voltage drop across a small resistor with the voltage of the source.
Claims3
The combination of
- a battery,
- an inverter having an input and an output, said input being coupled to said battery,
- a transformer having primary and secondary windings, said primary winding being coupled to said output of said inverter,
- a rectifier having an input and an output, said input being coupled to said secondary winding of said transformer,
- a capacitor to be charged coupled to the output of said rectifier,
- a plurality of variable impedance devices,
- switching means coupled to said capacitor for connecting different points on said primary winding through a respective one of said variable impedance devices so as to provide a current return path to said inverter as the voltage across said capacitor increases through pedetermined values,
- a resistor connected in series with said variable impedance devices, and
- means for varying the impedance of the variable impedance device that is in the current return path in accordance with a comparison between the voltage across said resistor and the voltage of said battery.
6 more elements
In a defibrillator, the combination of
- a battery,
- a visual display device coupled to said battery so as to be powered thereby,
- an inverter having an input and an output, said input being coupled to said battery,
- a transformer having primary and secondary windings, said primary winding being coupled to said output of said inverter,
- a rectifier having an input and an output, said input being coupled to said secondary winding of said transformer,
- a capacitor to be charged coupled to the output of said rectifier, and
- means for maintaining the current in said primary winding at a value determined by the current and the voltage of said battery so as to prevent said current from reducing the voltage of said battery to a point where the operation of said visual display means is impaired.
4 more elements
A circuit for deriving a high direct current charging potential for a capacitor from a source of direct current voltage having a lower value comprising,
- input terminals between which a source of direct current potential may be connected, one terminal being connected to a point of reference potential,
- an inverter having an input and an output, said input being connected to said input terminals,
- a transformer having primary and secondary windings one end of said primary winding being coupled to the output of said inverter,
- a rectifier having output terminals between which a capacitor may be connected and input terminals, said input terminals being coupled to said secondary winding of said transformer, one of said output terminals being connected to said point of reference potential,
- a resistor having one end connected to said point of reference potential,
- a plurality of variable impedances, each having one side thereof coupled to a different point on said primary winding of said transformer and the other side thereof connected to the other end of said resistor, each of said impedances normally having a high value,
- switching means responsive to the voltage at the output of said rectifier for causing said variable impedance connected to the point on said primary winding that is most remote from the end of the primary winding that is coupled to said inverter to have a low value only while said voltage is below a given value and to cause a variable impedance that is connected to the point on said primary winding of said transformer that is next nearer to the end of said primary winding that is coupled to said inverter to have a low value only when the said voltage is greater than said given value, and
- means for tending to change the value of the one of said variable impedances having a low value in the same sense as the change in the voltage across said resistor and in the opposite sense with respect to changes in a direct current voltage appearing between said input terminals.
5 more elements
Dependencies are inferred from the claim text.