H-bridge circuit for generating a high-energy biphasic waveform in an external defibrillator
First Claim
1. In an external defibrillator for applying a biphasic defibrillation pulse to a patient through first and second electrodes when said first and second electrodes are coupled to a patient, said external defibrillator including an energy storage capacitor having first and second leads and a charging system for charging said energy storage capacitor, said external defibrillator also including an H-bridge output circuit with four legs for switchably coupling the energy storage capacitor to the first and second electrodes in order to conduct the energy stored in the energy storage capacitor to a patient, a first switch in the first leg of the H-bridge output circuit coupled between the first lead of the energy storage capacitor and the first electrode, a second switch in the second leg of the H-bridge output circuit coupled between the second lead of the energy storage capacitor and the second electrode, a third switch in the third leg of the H-bridge output circuit coupled between the first lead of the energy storage capacitor and the second electrode, and a fourth switch in the fourth leg of the H-bridge output circuit coupled between the second lead of the energy storage capacitor in the first electrode, said external defibrillator further comprising a control circuit coupled to said first, second, third, and fourth switches for controlling said first, second, third, and fourth switches, the control circuit placing the first and second switches in a conducting state for a first period to conduct energy stored in the energy storage capacitor to the first and second electrodes and thereby generate the first phase of a biphasic defibrillation pulse for application to a patient, the control circuit placing the third, and fourth switches in a conducting state for a second period to conduct energy stored in the energy storage capacitor to the first and second electrodes and thereby generate the second phase of a biphasic defibrillation pulse for application to a patient, the improvement comprising:
- (i) causing said charging system to charge said energy storage capacitor to a charge level of at least approximately 200 joules; and
(ii) forming said first, second, third, and fourth switches of components capable of delivering at least approximately 200 joules to the first and second electrodes for application to a patient.
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Accused Products
Abstract
An external defibrillator (8) with an output circuit (14) having four legs arrayed in the form of an "H" (an "H-bridge") is disclosed. Each leg of the output circuit contains a solid-state switch (31, 32, 33, 34). By selectively switching on pairs of switches in the H-bridge, a biphasic defibrillation pulse may be applied to a patient. The switches in three of the legs of the H-bridge output circuit are preferably silicon controlled rectifiers (SCRs). Gate drive circuits (51, 53, 54) are coupled to the SCRs to bias the SCRs with a voltage that allows the SCRs to remain turned-on even when conducting low current. The switch in the fourth leg is preferably a pair of insulated gate bipolar transistors (IGBTs) coupled in series. A gate drive circuit (52) is coupled to the gate of the IGBTs to provide a slow turn-on and a fast turn-off of the IGBTs. The gate drive circuit (52) also biases the IGBTs with a sufficient voltage to allow the IGBTs to withstand a shorted discharge of the external defibrillator through the output circuit.
52 Citations
47 Claims
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1. In an external defibrillator for applying a biphasic defibrillation pulse to a patient through first and second electrodes when said first and second electrodes are coupled to a patient, said external defibrillator including an energy storage capacitor having first and second leads and a charging system for charging said energy storage capacitor, said external defibrillator also including an H-bridge output circuit with four legs for switchably coupling the energy storage capacitor to the first and second electrodes in order to conduct the energy stored in the energy storage capacitor to a patient, a first switch in the first leg of the H-bridge output circuit coupled between the first lead of the energy storage capacitor and the first electrode, a second switch in the second leg of the H-bridge output circuit coupled between the second lead of the energy storage capacitor and the second electrode, a third switch in the third leg of the H-bridge output circuit coupled between the first lead of the energy storage capacitor and the second electrode, and a fourth switch in the fourth leg of the H-bridge output circuit coupled between the second lead of the energy storage capacitor in the first electrode, said external defibrillator further comprising a control circuit coupled to said first, second, third, and fourth switches for controlling said first, second, third, and fourth switches, the control circuit placing the first and second switches in a conducting state for a first period to conduct energy stored in the energy storage capacitor to the first and second electrodes and thereby generate the first phase of a biphasic defibrillation pulse for application to a patient, the control circuit placing the third, and fourth switches in a conducting state for a second period to conduct energy stored in the energy storage capacitor to the first and second electrodes and thereby generate the second phase of a biphasic defibrillation pulse for application to a patient, the improvement comprising:
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(i) causing said charging system to charge said energy storage capacitor to a charge level of at least approximately 200 joules; and (ii) forming said first, second, third, and fourth switches of components capable of delivering at least approximately 200 joules to the first and second electrodes for application to a patient. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. In an external defibrillator for applying a biphasic defibrillation pulse to a patient through a pair of electrodes when said pair of electrodes are coupled to a patient, said external defibrillator including an energy storage capacitor having first and second leads, said external defibrillator also including an H-bridge output circuit having four legs for switchably coupling the energy storage capacitor to the pair of electrodes in order to conduct the energy stored in the energy storage capacitor to the pair of electrodes for application to a patient and a control circuit for controlling the operation of said H-bridge output circuit, the improvement comprising an improved H-bridge output circuit and an improved control circuit, said improved H-bridge output circuit comprising:
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(a) a first silicon controlled rectifier (SCR) in the first leg of the H-bridge output circuit coupled between the first lead of the energy storage capacitor and one of the pair of electrodes; (b) an insulated gate bipolar transistor (IGBT) in the second leg of the H-bridge output circuit coupled between the second lead of the energy storage capacitor and the other of the pair of electrodes; (c) a second SCR in the third leg of the H-bridge output circuit coupled between the first lead of the energy storage capacitor and the other of the pair of electrodes; and (d) a third SCR in the fourth leg of the H-bridge output circuit coupled between the second lead of the energy storage capacitor and the one of the pair of electrodes; and said improved control circuit controlling the first, second, and third SCRs and the IGBT, such that;
(i) the first SCR and the IGBT are placed in a conducting state for a first period to conduct energy stored in the energy storage capacitor to the pair of electrodes for application to a patient and thereby generate a first phase of a biphasic defibrillation pulse; and
(ii) the second, and third SCRs are placed in a conducting state for a second period to conduct energy stored in the energy storage capacitor to the pair of electrodes for application to a patient and thereby generate a second phase of said biphasic defibrillation pulse that is opposite in polarity to the first phase of said biphasic defibrillation pulse. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
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- 37. In an external defibrillator for applying a biphasic defibrillation pulse to a patient through first and second electrodes when said first and second electrodes are coupled to a patient, said external defibrillator including an energy storage capacitor having first and second leads, said external defibrillator also including an H-bridge output circuit having four legs each including one or more solid state switches for switchably coupling the energy storage capacitor to the first and second electrodes in order to conduct the energy stored in the energy storage capacitor to the first and second electrodes for application to a patient, the improvement comprising a drive circuit for said solid state switches that maintains said solid state switches in a conducting state at low defibrillation pulse energy levels such as the defibrillation pulse energy levels used in surgery to directly defibrillate a patient.
- 42. In an external defibrillator for applying a defibrillation pulse to a patient through a pair of electrodes when said electrodes are coupled to a patient, said external defibrillator including a housing and defibrillator circuitry for providing defibrillation pulses and control circuitry for controlling the operation of said defibrillator circuitry, said control circuitry including control knobs mounted in said housing, the improvement comprising isolation circuitry for isolating said control circuitry and, thus, said housing from said defibrillator circuitry.
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45. In an external defibrillator for applying a biphasic defibrillation pulse to a patient through first and second electrodes when said first and second electrodes are coupled to the patient, said external defibrillator including an energy storage capacitor having first and second leads, said external defibrillator also including an H-bridge output circuit having four legs for switchably coupling the first and second leads of the energy storage capacitor to the first and second electrodes in order to conduct the energy stored in the energy storage capacitor to the first and second electrodes for application to a patient, a first switch in the first leg of the H-bridge output circuit coupled between the first lead of the energy storage capacitor and the first electrode, a second switch in the second leg of the H-bridge output circuit coupled between the second lead of the energy storage capacitor and the second electrode, a third switch in the third leg of the H-bridge output circuit coupled between the first lead of the energy storage capacitor and the second electrode, a fourth switch in the fourth leg of the H-bridge output circuit coupled between the second lead of the energy storage capacitor and the first electrode, the improvement comprising:
- (i) at least one of the first, second, third, or fourth switches including an isolated gate bipolar transistor (IGBT); and
(ii) a gate drive circuit, the gate drive circuit biasing the gate of the IGBT with sufficient voltage for the IGBT to be able to withstand a current pulse of up to 400 amps without damage to the IGBT. - View Dependent Claims (46)
- (i) at least one of the first, second, third, or fourth switches including an isolated gate bipolar transistor (IGBT); and
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47. In an external defibrillator for applying a biphasic defibrillation pulse to a patient through first and second electrodes when said first and second electrodes are coupled to a patient, said external defibrillator including an energy storage capacitor having first and second leads, said external defibrillator also including an H-bridge output circuit with four legs for switchably coupling the energy storage capacitor to the first and second electrodes in order to conduct the energy stored in the energy storage capacitor to the first and second electrodes for application to a patient, a first switch in the first leg of the H-bridge output circuit coupled between the first lead of the energy storage capacitor and the first electrode, a second switch in the second leg of the H-bridge output circuit coupled between the second lead of the energy storage capacitor and the second electrode, a third switch in the third leg of the H-bridge output circuit coupled between the first lead of the energy storage capacitor and the second electrode, a fourth switch in the fourth leg of the H-bridge output circuit coupled between the second lead of the energy storage capacitor and the first electrode, the improvement comprising:
- (i) at least one of the first, second, third, or fourth switches of the H-bridge output circuit including a silicon controlled rectifier (SCR), and at least one other of the first, second, third, or fourth switches including an insulated gate bipolar transistor (IGBT); and
(ii) a gate drive circuit connected to said IGBT for turning on said IGBT at a rate that is slow enough to prevent the SCR from spuriously firing.
- (i) at least one of the first, second, third, or fourth switches of the H-bridge output circuit including a silicon controlled rectifier (SCR), and at least one other of the first, second, third, or fourth switches including an insulated gate bipolar transistor (IGBT); and
Specification