Battery impedance measurement apparatus
First Claim
1. In implantable electrical medical apparatus having telemetry means and battery means, battery impedance measurement apparatus comprising:
- a. means for selectively isolating said battery means from said medical apparatus;
b. first circuit means selectively connectable in circuit with said battery means and including first current source means and reference impedance means;
c. second circuit means selectively connectable in circuit with said battery means and including second current source means;
d. control means for alternately connecting said first circuit means to said battery means for driving a first current and connecting said second circuit means to said battery means for driving a second current;
e. measurement means for measuring the ratio of said first current to said second current; and
,f. means connecting said measurement means to said telemetry means for transmission of said ratio.
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Accused Products
Abstract
A battery impedance measurement apparatus for battery powered implantable medical apparatus in which current source means and reference impedance means are selectively connected across the battery after it has been isolated from the medical apparatus, and the resulting currents of interest are digitized to provide a factor directly related to the value of the internal impedance of the battery. The digitized value may be telemetered out of the implanted medical apparatus to enable critical decisions to be made based on the remaining life of the implanted battery. The same measurement apparatus can be used to form an accurate end-of-life signal.
154 Citations
18 Claims
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1. In implantable electrical medical apparatus having telemetry means and battery means, battery impedance measurement apparatus comprising:
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a. means for selectively isolating said battery means from said medical apparatus; b. first circuit means selectively connectable in circuit with said battery means and including first current source means and reference impedance means; c. second circuit means selectively connectable in circuit with said battery means and including second current source means; d. control means for alternately connecting said first circuit means to said battery means for driving a first current and connecting said second circuit means to said battery means for driving a second current; e. measurement means for measuring the ratio of said first current to said second current; and
,f. means connecting said measurement means to said telemetry means for transmission of said ratio. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. In implantable electrical medical apparatus having telemetry means and having battery means, battery impedance measurement apparatus comprising:
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a. means for electrically isolating said battery means from said medical apparatus; b. first current source means; c. means for selectively connecting said first current source means in circuit with said battery means to cause a first current; d. second current source means; e. means for selectively connecting said second current source means in circuit with said battery means to cause a second current; f. reference impedance circuit means; g. means for comparing said first and second currents; h. means connecting said reference impedance circuit means to said means for comparing for developing a signal from said first and second current indicative of the internal impedance of said battery means; and
,i. means connecting said signal to said telemetry means. - View Dependent Claims (11, 12)
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13. In body implantable, battery powered medical apparatus having telemetry means, battery impedance measurement apparatus comprising:
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a. first adjustable current source means; b. second adjustable current source means; c. reference circuit means; d. comparator means having first and second input means and output means; e. current adjustment means connected between said comparator output means and said first and second current source means for adjusting said first and second current source means dependent on the output of said comparator means; f. first connection means for selectively disconnecting said battery means from said medical apparatus; g second connection means for selectively connecting said first current source means in circuit with said battery means to provide a first current to said comparator means first input means, for connecting said comparator means second input means to circuit ground, and for connecting said current adjustment means to said first adjustable current source means; and
,h. third connection means for selectively connecting said second current source means in circuit with said battery means to provide a second current to said comparator means first input means, for connecting said comparator means second input means to said reference circuit means, and for connecting said current adjustment means to said second adjustable current source means. - View Dependent Claims (14)
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15. In implantable medical apparatus having telemetry means and battery means, battery impedance measurement apparatus comprising:
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a. means for isolating said battery means from said medical apparatus during an impedance measurement period; b. measurement means including reference circuit means having reference voltage means and reference impedance means; c. means for zeroing said measurement means including a first current generator selectively connected across said battery means and to said measurement means, and means for varying the output of said first generator means; d. means for developing and storing a signal indicative of the internal battery impedance of said battery means, including a second current generator selectively connected across said battery means and to said zeroed measurement means for comparison with said reference circuit means, and means for varying the output of said second generator means; and
,e. means connecting said telemetry means to said measurement means for transmission of said stored signal. - View Dependent Claims (16, 17, 18)
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Specification