Method and apparatus for low power regulated output in battery powered electrotherapy devices

• US 6,076,018 A
• Filed: 09/04/1998
• Issued: 06/13/2000
• Est. Priority Date: 09/04/1998
• Status: Expired due to Term

• Current Assignee: ReliefBand Technologies, LLC
• Original Assignee: Woodside Biomedical, Inc. (Abbott Laboratories)
• Inventors: Grey, Thomas, Sturman, Andy
• Primary Examiner(s): Schaetzle, Kennedy
• Application Number:
  US09/148,837
• Time in Patent Office: 648 Days
• Field of Search: 607/4, 607/5, 607/2, 607/11, 607/7, 607/46, 607/48, 607/39-42, 607/72, 607/74
• US Class Current: 607/72
• CPC Class Codes: A61N 1/36034 specified by the stimulation parameters
• CPC Class Codes: A61N 1/378 Electrical supply
• CPC Class Codes: H02J 2310/23 The load being a medical device, a medical implant, or a life supporting device
• CPC Class Codes: H02J 7/0063 with circuits adapted for supplying loads from the battery
• CPC Class Codes: H02J 7/00711 with introduction of pulses during the charging process
• CPC Class Codes: H02J 7/007182 in response to battery voltage

Abstract

A device for controlling the discharge of a battery supplying an intermittent load, such as a nerve stimulation device. The device includes a controller which operates a switched inductor to feed a capacitor with numerous small pulses from the battery, thereby building up the charge and voltage on the capacitor, and occasionally discharging the capacitor to a load. The capacitor discharge is at a higher current than the small pulses from the battery, so the battery is drained at small instantaneous discharge rates compared to the high instantaneous discharge current from the capacitor.

Claims

1. An apparatus for regulating the output in a battery powered electrotherapy device comprising:

a control means which activates a switched inductor by connecting said switched inductor to a battery supply such that the battery supply outputs a charging pulse to the switched inductor;

wherein said control means deactivates the switched inductor causing said switched inductor to deliver a charge from the switched inductor to a storage capacitor, said deactivating of the switched inductor causing voltage to build up on the storage capacitor;

wherein said control means monitors the voltage built up on the storage capacitor using a voltage divider connected to a voltage comparator until the voltage on the storage capacitor reaches a predetermined voltage at which point it delivers a capacitor discharge pulse from the storage capacitor to an output stage;

wherein said control means controls the width and frequency of the battery supply charging pulses so that battery discharge pulses are made at lower amperage than the capacitor discharge pulses; and

the output stage comprises electrodes adapted to transmit electrotherapy pulses to the body of a patient.

2. An apparatus for regulating the output in a battery powered electrotherapy device comprising:

a control means which activates a switched inductor by connecting said switched inductor to a battery supply such that the battery supply outputs a charging pulse to the switched inductor;

wherein said control means deactivates the switched inductor causing said switched inductor to deliver a charge from the switched inductor to a storage capacitor, said deactivating of the switched inductor causing voltage to build up on the storage capacitor;

wherein said control means monitors the voltage built up on the storage capacitor using a voltage divider connected to a voltage comparator until the voltage on the storage capacitor reaches a predetermined voltage at which point it delivers said voltage from the storage capacitor to an output stage;

wherein said control means controls the width and frequency of the battery supply charging pulses so that battery discharge pulses are made at lower amperage than the capacitor discharge pulses;

wherein said control means counts the number of charge pulses from the battery supply needed to achieve a predetermined voltage such that as the battery supply is depleted, more charge pulses are ordered to be sent from the battery supply to the storage capacitor;

wherein said control means determines that the charge pulses count reaches a predetermined charge pulse count value equal to a predetermined percent of total value, said control means changes an indicator from normal to a low battery warning and continues to deliver therapeutic pulses, said predetermined value calculated as a percentage of the total time that the control can maintain the stimulation output on average for the type of battery supply used; and

wherein said control means, once it determines that it is unable to regulate the output due to depleted battery supply, stops delivering therapeutic output pulses.

3. An apparatus for regulating the output in a battery powered electrotherapy device comprising:

a control means which activates a switched inductor by connecting said switched inductor to a battery supply such that the battery supply outputs a charging pulse to the switched inductor, thereby causing a voltage to build up on a storage capacitor;

wherein said control means deactivates the switched inductor causing said switched inductor to deliver residual charge from the switched inductor to said storage capacitor, said deactivating of the switched inductor causing additional voltage to build up on said low voltage storage capacitor;

wherein said control means monitors the voltage built up on the storage capacitor using a voltage divider connected to a voltage comparator, and the control means causes the capacitor to discharge to an output stage when the voltage on the storage capacitor reaches a predetermined voltage;

wherein said control means determines the width and frequency of the battery supply charging pulses low enough such that the resulting average electrical current draw from the battery supply is low enough to not degrade the battery performance and battery life and high enough so that there is sufficient time for the therapeutic pulses to be generated at the required frequency;

wherein said control means counts the number of charge pulses from the battery supply needed to achieve a predetermined voltage such that as the battery supply is depleted, more charge pulses are ordered to be sent from the battery supply to the storage capacitor;

wherein said control means determines that the charge pulses count reaches a predetermined charge pulse count value equal to a predetermined percent of total value, said control means changes an indicator from normal to a low battery warning and continues to deliver therapeutic pulses, said predetermined value calculated as a percentage of the total time that the control can maintain the stimulation output on average for the type of battery supply used; and

wherein said control means, once it determines that it is unable to regulate the output due to a depleted battery supply, stops delivering therapeutic output pulses.

4. The device of claim 3 wherein the voltage divider is operably connected to a switch for selecting at least one voltage division setting said switch being operable by a user of the device.

5. The device of claim 3 wherein the voltage comparator transmits a signal to the control means when the voltage on the storage capacitor has reached a predetermined voltage.

6. The device of claim 3 wherein the output stage steps up the voltage and delivers it to the electrodes thereby generating a therapeutic electrical pulse to the user.

7. A device for providing a pulsed electrical stimulus to a nerve in the body of a patient, wherein said device is battery operated, said device comprising:

an electrode adapted to transmit electrotherapy pulses to the body of a patient in the vicinity of the nerve to be stimulated;

a capacitor and a first switch means for operably and intermittently connecting the capacitor to the electrode;

a battery and a second switch means operably connecting the battery to the capacitor;

control means for operating the second switch to periodically connect the battery to the capacitor, thereby transferring charge from the battery to the capacitor, and periodically connecting the capacitor to the electrode after a desired charge has been accumulated on the capacitor to apply a pulse of electrical stimulus to the nerve in the body; and

a transformer interposed between the capacitor and the electrode.

8. The device of claim 7 wherein the transformer is designed to step up the voltage of the pulse of electrical stimulus and transmits a responsive pulse of electrical stimulus to the electrode, said responsive pulse of electrical stimulus being at a voltage higher than the pulse of electrical stimulus from the capacitor.

9. A method for controlling the discharge of a battery to a load, said method comprising:

providing a switched inductor, said switched inductor having an inductor input switch with an input adapted to be connected to the battery, said switched inductor having an output;

providing a capacitor adapted to be placed in circuit with the output of the inductor and collect current discharged from the inductor;

providing a capacitor output switch in circuit with the capacitor, said capacitor output switch adapted to be connected to the load;

providing a control module to control the operation of the inductor input switch and the capacitor output switch, and programming the control module to;

monitor the voltage on the storage capacitor;

operate the inductor input switch to draw a plurality of battery discharge pulses from the battery and allow the discharge pulses to cause a build up of voltage on the capacitor, and count the number of battery discharge pulses necessary to achieve a predetermined maximum voltage on the capacitor;

use the counted number of battery discharge pulses to determine the expected number of pulses necessary to achieve a predetermined desired output voltage on said storage capacitor intermediate between zero and the predetermined maximum voltage;

thereafter operate the inductor input switch to draw the expected number of battery discharge pulses from the battery to allow the discharge pulses to cause a build up of voltage on the capacitor, and operate the capacitor output switch to connect the capacitor to the load.