Pulse rate monitor
First Claim
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1. In a portable heart pulse rate monitor device of the type having a radiation source in proximity to a radiation sensor with the transmission of radiation between the source and sensor modulated by capillary blood flow of a finger placed in proximity to both the radiation source and radiation sensor;
- an electronic circuit to power the radiation source and radiation sensor and to amplify and process the sensor'"'"'s output signal; and
a display means to furnish the user with a direct reading of the user'"'"'s pulse rate in beats per minute, the improvement comprising;
a phototransistor acting as the radiation sensor and an active load connected to the phototransistor, the active load comprising a transistor with a unidirectional feedback circuit, connected between base and collector of the transistor, which favors signal variations from the quiescent operating level resulting from reductions in radiation received by the phototransistor, as opposed to signals resulting from increase in radiation to the phototransistor.
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Abstract
A pulse rate monitor for use while exercising. A clothespin type finger clip remote from the counting and display unit grips the user'"'"'s finger in a predictable, mechanically stable manner. A light emitting diode, strobed to reduce battery drain, transmits infrared radiation through the finger, and electronic circuitry monitors the modulation of radiation caused by changes in capillaries with each heart beat. The circuitry includes an active load for the phototransistor, which, by means of bandpass filtered feedback, enhances heart beat signal and reduces sensitivity to ambient light, noise, and variations in phototransistor characteristics.
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Citations
2 Claims
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1. In a portable heart pulse rate monitor device of the type having a radiation source in proximity to a radiation sensor with the transmission of radiation between the source and sensor modulated by capillary blood flow of a finger placed in proximity to both the radiation source and radiation sensor;
- an electronic circuit to power the radiation source and radiation sensor and to amplify and process the sensor'"'"'s output signal; and
a display means to furnish the user with a direct reading of the user'"'"'s pulse rate in beats per minute, the improvement comprising;
a phototransistor acting as the radiation sensor and an active load connected to the phototransistor, the active load comprising a transistor with a unidirectional feedback circuit, connected between base and collector of the transistor, which favors signal variations from the quiescent operating level resulting from reductions in radiation received by the phototransistor, as opposed to signals resulting from increase in radiation to the phototransistor.
- an electronic circuit to power the radiation source and radiation sensor and to amplify and process the sensor'"'"'s output signal; and
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2. In a portable heart pulse rate monitor device of the type having a radiation source in proximity to a radiation sensor with the transmission of radiation between the source and sensor modulated by capillary blood flow of a finger placed in proximity to both the radiation source and radiation sensor;
- an electronic circuit to power the radiation source and radiation sensor and to amplify and process the sensor'"'"'s output signal; and
a display means to furnish the user with a direct reading of the user'"'"'s pulse rate in beats per minute, the improvement comprising;
a constant current source within the electronic circuit connected to and charging a capacitor to convert the sum of time periods between heart beat pulses into a measurable voltage, the constant current source comprising a PNP transistor and emitter connected to a counter circuit, collector connected to the capacitor, and base connected to a temperature compensating circuit;a counter circuit, connected to the radiation sensor by means of amplifiers and filter means, regularly initiating a count of a specific number of heart beat signal pulses received from the radiation sensor, and connected to and controlling the constant current source; a calibration voltage source connected to the battery comprising a PNP transistor with variable resistor collector load; a temperature compensating circuit comprising a light emitting diode connected to the base of the calibration circuit transistor and the base of the constant current source transistor, the light emitting diode selected to have temperature characteristics matching those of the PNP transistor; an analog to digital converter circuit connected to the constant current source charged capacitor and the calibration voltage source; and a digital driver circuit connected to the analog to digital converter circuit and to a digital display means.
- an electronic circuit to power the radiation source and radiation sensor and to amplify and process the sensor'"'"'s output signal; and
Specification
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Current AssigneeNovatec Incorporated
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Original AssigneeNovatec Incorporated
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InventorsO'Connor, Arthur H., Rossman, Robert A.
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Primary Examiner(s)Michell, Robert W.
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Assistant Examiner(s)Jaworski, Francis J.
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Application NumberUS06/123,351Time in Patent Office964 DaysField of Search128/633, 128/665-667, 128/687-690, 128/706US Class Current600/502CPC Class CodesA61B 5/02416 using photoplethysmograph s...A61B 5/02438 with portable devices, e.g....
