Implantable stimulator having an efficient output generator
First Claim
1. An output circuit in an implantable device comprising:
- a hermetic enclosure, the hermetic enclosure containing an energy source;
a source circuit for providing power from the energy source, the source circuit housed within the hermetic enclosure;
at least two small size output capacitors housed with the hermetic enclosure;
an output circuit adapted to be connected to the load, the output circuit housed within the hermetic enclosure;
pulse means for providing a pulse signal having a predetermined pulse duration, the pulse means housed with the hermetic enclosure; and
switching means housed with the hermetic enclosure, the switching means enabled by the pulse signal for the pulse duration, for alternately switching each said capacitor into a circuit with the output circuit and into a circuit with the source circuit wherein during the pulse duration at least one of the capacitors is substantially always delivering power to the load.
1 Assignment
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Accused Products
Abstract
An output pulse generator is provided which is particularly suitable for implantable medical simulators, such as cardiac pacemakers, where there is a high premium on efficient energy transfer from the battery source to the output load. A plurality of relatively small size output capacitor are utilized in combination with a switching circuit for alternately charging respective capacitors and then discharging them through the load in such a manner that there is always one capacitor providing a substantially constant output voltage while at least one other capacitors is being recharged. Different combinations of switching networks are used to provide programmable output voltage levels. The use of relatively small capacitors, e.g., in the range of 0.1-0.5 F, along with a relatively high drive frequency, e.g., 32 kHz, enables substantially continuous transfer of energy from the battery to the capacitors only during the time of pulse output, and high efficiency generation of a stimulus pulse with a substantially constant voltage level throughout the pulse duration. Variation of the drive frequency is done in order to adjust the generated pulses to the output load.
44 Citations
30 Claims
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1. An output circuit in an implantable device comprising:
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a hermetic enclosure, the hermetic enclosure containing an energy source; a source circuit for providing power from the energy source, the source circuit housed within the hermetic enclosure; at least two small size output capacitors housed with the hermetic enclosure; an output circuit adapted to be connected to the load, the output circuit housed within the hermetic enclosure; pulse means for providing a pulse signal having a predetermined pulse duration, the pulse means housed with the hermetic enclosure; and switching means housed with the hermetic enclosure, the switching means enabled by the pulse signal for the pulse duration, for alternately switching each said capacitor into a circuit with the output circuit and into a circuit with the source circuit wherein during the pulse duration at least one of the capacitors is substantially always delivering power to the load. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An implantable stimulus apparatus having an output circuit, in combination with an energy supply, for delivering stimulus pulses to a load, the output circuit further comprising:
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capacitive storage means for storing energy; pulse timing means for generating pulse timing signals, each said pulse timing signal having a predetermined pulse duration; first transfer means operative substantially only during each said pulse duration for transferring energy from the energy supply to the storage means at a substantially constant rate during the duration; and second transfer means operative for transferring energy from the capacitive storage means to the load during each said pulse duration, wherein the second transfer means delivers a stimulus pulse during each said pulse duration, with substantially all of the energy delivered to the load during each stimulus pulse being transferred from the energy supply during the duration of the each pulse. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. An implantable pacemaker for generating pace pulses, comprising an energy source, control means for generating pace pulse control signals, the signals having a predetermined pulse duration corresponding to the timing of each said pace pulse, and output means for generating the pace pulses under control of the control signals, the output means further comprising:
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at least two capacitors; output terminals, the output terminals outputting a pacing pulse, the output terminals coupled to the at least two capacitors; a drive generator for generating a drive signal having a cycle period less than the duration; and switching circuit means enabled during each said pulse duration for switching a first of the capacitors to the energy source and a second of the capacitors to the output terminals during a first portion of each said drive cycle period and alternatingly switching the second of the capacitors to the energy source and the first of the capacitors to the output terminals during a second portion of each said drive cycle period, wherein during the pulse duration an output is provided to the output terminals alternately by the first and second capacitors. - View Dependent Claims (18, 19)
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20. An output circuit for an implantable stimulator having a hermetic enclosure, comprising:
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an energy source; a drive circuit for producing a high frequency switching signal, the drive circuit coupled to the energy source; first and second sets of capacitors, said capacitors coupled to the energy source; output terminals, said output terminals coupled to said capacitors; and switching means for switching the sets of capacitors in an alternating manner wherein the first set is charged by the energy source while the second set is connected to the output terminals, and the second set is charged by the energy source while the first set is connected to the output terminals. - View Dependent Claims (21, 22, 23, 24, 25, 26)
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27. A device for providing an output pulse of substantially constant voltage for delivery to a load, comprising:
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an energy source; a set of small sized capacitors; pulse means for defining a pulse to be generated, the pulse having a duration; transfer means operative during the duration for cyclically discharging energy from the capacitors to the load and for re-charging the capacitors from the energy source at a rate permitting the capacitors to discharge no more than about 85%-95%, the transfer means also having connecting means for connecting at least one of the capacitors to discharge energy to the load at all times during the pulse duration and producing an output pulse with a voltage that varies by no more than about 85-95% during the duration. - View Dependent Claims (28, 29, 30)
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Specification