Reduced wire count voltage drop sense
First Claim
1. A reduced wire count voltage-drop sense system for use in photoplethysmography comprising:
- an input drive lead extending between an associated input drive lead terminal and an associated light signal emitter input terminal;
a return drive lead extending between a light signal emitter output terminal and a return drive lead terminal; and
a sense lead extending between said light signal emitter output terminal and a sense lead terminal;
wherein a voltage drop across a light signal emitter operable to illuminate a patient tissue site and connected between the light signal emitter input terminal and the light signal emitter output terminal when a drive current is applied therethrough via said input drive lead is determinable from a first voltage drop and a second voltage drop, said first voltage drop being measurable across the input drive lead terminal and the sense lead terminal and said second voltage drop being measurable across the sense lead terminal and the return drive lead terminal.
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Accused Products
Abstract
The present invention provides a reduced wire count voltage-drop sense system and method wherein the voltage drop across a load device is determinable using only one sense lead regardless of the number of load devices. In one embodiment, the voltage drop across any one of four LEDs (220A-D) in a photoplethysmographic probe when a drive current is applied therethrough via one of four input drive leads (230A-D) connected to separate LED terminals (222A-D) is determinable from a first voltage drop and a second voltage drop, for example, by subtracting the second voltage drop, or a portion thereof, from the first voltage drop. The first voltage drop is measurable across a terminal (232A-D) of the input drive lead (230A-D) connected to the LED (220A-D) across which the voltage drop is to be determined and a terminal (252) of a sense lead (250) connected to a common LED terminal (224). The second voltage drop is measurable across the sense lead terminal (252) and a terminal (242) of a common drive lead (240) connected to the common LED terminal (224).
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Citations
34 Claims
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1. A reduced wire count voltage-drop sense system for use in photoplethysmography comprising:
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an input drive lead extending between an associated input drive lead terminal and an associated light signal emitter input terminal;
a return drive lead extending between a light signal emitter output terminal and a return drive lead terminal; and
a sense lead extending between said light signal emitter output terminal and a sense lead terminal;
wherein a voltage drop across a light signal emitter operable to illuminate a patient tissue site and connected between the light signal emitter input terminal and the light signal emitter output terminal when a drive current is applied therethrough via said input drive lead is determinable from a first voltage drop and a second voltage drop, said first voltage drop being measurable across the input drive lead terminal and the sense lead terminal and said second voltage drop being measurable across the sense lead terminal and the return drive lead terminal. - View Dependent Claims (2, 3, 4, 5)
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6. A reduced wire count voltage-drop sense system for use in photoplethysmography comprising:
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a plurality of input drive leads, each said input drive lead extending between an associated separate one of a corresponding plurality of input drive lead terminals associated therewith and an associated separate one of a corresponding plurality of light signal emitter input terminals;
a common return lead extending between a common light signal emitter output terminal and a common return lead terminal; and
a sense lead extending between said common light signal emitter output terminal and a sense lead terminal;
wherein a voltage drop across any one of a plurality of light signal emitters operable to illuminate a patient tissue site and connected between separate ones of said light signal emitter input terminals and said common light signal emitter output terminal when a drive current is applied therethrough via an associated one of said input drive leads is determinable from a first voltage drop and a second voltage drop, said first voltage drop being measurable across said input drive lead terminal associated with said input drive lead associated with said any one of said plurality of light signal emitters and said sense lead terminal, said second voltage drop being measurable across said sense lead terminal and said common return lead terminal. - View Dependent Claims (7, 8, 9, 10, 11, 12)
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13. A reduced wire count photoplethysmographic probe comprising:
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a plurality of light signal emitters operable to illuminate a patient tissue site, each said light signal emitter having an input terminal and an output terminal, the output terminals of said light signal emitters being connected in common with one another;
a plurality of input drive leads, each said input drive lead being associated with one of said light signal emitters and extending between an associated separate one of a corresponding plurality of input drive lead terminals and the input terminal of its associated light signal emitter;
a common return drive lead extending between the commonly connected output terminals of the light signal emitters and a common return drive lead terminal; and
a sense lead extending between the commonly connected output terminals of said light signal emitters and a sense lead terminal;
wherein a voltage drop across any one said light signal emitters when it is turned on by applying a drive current therethrough via said input drive lead associated therewith is determinable from a first voltage drop and a second voltage drop, said first voltage drop being measurable across the input drive lead terminal associated with said input drive lead associated with said any one of said light signal emitters and the sense lead terminal, said second voltage drop being measurable across the sense lead terminal and the common return drive lead terminal. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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20. A reduced wire count photoplethysmographic probe comprising:
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at least two pairs of light signal emitters, each pair of light signal emitters being connected in a back-to-back relation with one another between an input terminal of said pair and an output terminal of said pair wherein one of the light signal emitters is forward biased and one is reverse biased when a voltage is applied across the input and output terminals of the pair, the output terminals of each pair of said light signal emitters being connected in common with one another;
a plurality of input drive leads, each said input drive lead being associated with one of said pairs of light signal emitters and extending between an associated separate one of a corresponding plurality of input drive lead terminals and the input terminal of its associated pair of light signal emitters;
a common return drive lead extending between the commonly connected output terminals of said pairs of light signal emitters and a common return drive lead terminal; and
a sense lead extending between the commonly connected output terminals of said pairs of light signal emitters and a sense lead terminal;
wherein a voltage drop across any one of said pairs of light signal emitters when a drive current is applied therethrough via said input drive lead associated therewith is determinable from a first voltage drop and a second voltage drop, said first voltage drop being measurable across the input drive lead terminal associated with said input drive lead associated with said any one of said pairs of light signal emitters and the sense lead terminal, said second voltage drop being measurable across the sense lead terminal and the common return drive lead terminal. - View Dependent Claims (21, 22, 23, 24, 25, 26)
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27. A method of determining a desired voltage drop across any one of a plurality of light signal emitters operable to illuminate a patient tissue site and having separate input terminals and commonly connected output terminals, said method comprising:
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measuring a first voltage drop across a sense lead terminal connected by a sense lead to the commonly connected output terminals of the light signal emitters and an input drive lead terminal connected by an input drive lead to the input terminal of the light signal emitter across which the desired voltage drop is to be determined when a drive current is supplied thereto via the input drive lead;
measuring a second voltage drop across the sense lead terminal and a common return drive lead terminal connected by a common return drive lead to the commonly connected output terminals of the light signal emitters; and
utilizing the first voltage drop and the second voltage drop to determine the desired voltage drop. - View Dependent Claims (28, 29, 30, 31)
subtracting the second voltage drop from the first voltage drop to determine the desired voltage drop.
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29. The method of claim 27 wherein when the common return drive lead has a different diameter than the input drive lead, said step of utilizing further comprises:
- multiplying the second voltage drop by a ratio of the cross-sectional area of the common return drive lead to the cross-sectional area of the input drive lead.
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30. The method of claim 27 wherein when drive currents are simultaneously supplied to more than one of the plurality of light signal emitters, said step of utilizing comprises:
subtracting a portion of the second voltage drop from the first voltage drop to determine the desired voltage drop.
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31. The method of claim 30 wherein said step of utilizing further comprises:
apportioning the second voltage drop in accordance with the level of each drive current that is supplied to the light signal emitters in order to obtain the portion of the second voltage drop that is subtracted from the first voltage drop in said subtracting step.
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32. A method of determining a desired voltage drop across any one of a plurality of light signal emitters operable to illuminate a patient tissue site and having separate input terminals and commonly connected output terminals, said method comprising:
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measuring a first voltage drop across a sense lead terminal connected by a sense lead to the commonly connected output terminals of the light signal emitters and ah input drive lead terminal connected by an input drive lead to the input terminal of the light signal emitter across which the desired voltage drop is to be determined when a drive current is supplied thereto via the input drive lead;
measuring a second voltage drop across the sense lead terminal and a common return drive lead terminal connected by a common return drive lead to the commonly connected output terminals of the light signal emitters; and
utilizing the first voltage drop and the second voltage drop to determine the desired voltage drop, wherein said step of utilizing comprises subtracting the second voltage drop from the first voltage drop to determine the desired voltage drop, and wherein, when the common return drive lead has a different diameter than the input drive lead, said step of utilizing further comprises multiplying the second voltage drop by a ratio of the cross-sectional area of the common return drive lead to the cross-sectional area of the input drive lead prior to subtracting the second voltage drop from the first voltage drop. - View Dependent Claims (33, 34)
apportioning the second voltage drop in accordance with the level of each drive current that is supplied to the light signal emitters in order to obtain the portion of the second voltage drop that is subtracted from the first voltage drop in said utilizing step.
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Specification