Portable digital heart rate meter/stethoscope
First Claim
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1. An electronic heart rate detector comprising:
- a transducer for providing an electrical signal in response to sounds, including heart sounds;
filter means for filtering said electrical signal, said filter means having a passband including frequencies characteristic of heart sounds and producing a filtered electrical signal;
means for detecting amplitude levels of said filtered electrical signal exceeding a predetermined threshold level and providing an output pulse of fixed duration in response to each amplitude level exceeding said threshold level, the output of said detecting means being connected to the input thereof, said detecting means including a comparator having an input connected to the output of said filter means for producing a first output pulse in response to each filtered electrical signal amplitude level exceeding said threshold level, the duration of said first output pulse corresponding to the duration of that portion of said amplitude level exceeding said threshold level;
means for selectively modifying the duration of said output pulse;
means responsive to the output of said pulse modifying means for producing a second output pulse of predetermined duration, the output of said second output pulse producing means being connected to the input of said comparator; and
means responsive to the output of said second output pulse producing means for producing a signal representative of a heart rate; and
means for displaying said signal as a detected heart rate.
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Abstract
Electrical signals corresponding to heart sounds detected by a pulse/sound transducer are filtered in a narrow bandpass filter whose pass band is centered on a characteristic heart sound frequency of 33 Hz. The filter improves signal-to-noise ratio and enables the transducer to be used over a patient'"'"'s clothing. The unfiltered signal is amplified and fed to binaural leads to provide the function of an electronic stethoscope. In addition, the filtered signal is converted into pulses in response to which a count corresponding to the detected heart rate is established in a counter and displayed as a digital heart rate indication.
57 Citations
20 Claims
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1. An electronic heart rate detector comprising:
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a transducer for providing an electrical signal in response to sounds, including heart sounds; filter means for filtering said electrical signal, said filter means having a passband including frequencies characteristic of heart sounds and producing a filtered electrical signal; means for detecting amplitude levels of said filtered electrical signal exceeding a predetermined threshold level and providing an output pulse of fixed duration in response to each amplitude level exceeding said threshold level, the output of said detecting means being connected to the input thereof, said detecting means including a comparator having an input connected to the output of said filter means for producing a first output pulse in response to each filtered electrical signal amplitude level exceeding said threshold level, the duration of said first output pulse corresponding to the duration of that portion of said amplitude level exceeding said threshold level;
means for selectively modifying the duration of said output pulse;
means responsive to the output of said pulse modifying means for producing a second output pulse of predetermined duration, the output of said second output pulse producing means being connected to the input of said comparator; andmeans responsive to the output of said second output pulse producing means for producing a signal representative of a heart rate; and means for displaying said signal as a detected heart rate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. An electronic heart rate detector, comprising:
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a transducer for converting sounds, including heart sounds, to an electrical signal; an audio amplifier connected to the output of said transducer and providing an audio output of said electrical signal for supply to an electro-acoustic transducer; a bandpass filter for filtering said electrical signal and producing a filtered electrical signal, said filter having a passband centered on a frequency of about 33 Hz; means for detecting the first and the second heart sounds of a heart cycle and providing an indication of said heart sounds, said means including a comparator having an input connected to the output of said filter for producing a first output pulse corresponding to each filtered electrical signal amplitude level exceeding a predetermined threshold level, the duration of said first output pulse corresponding to the duration that said amplitude level exceeds said threshold level, means for selectively adjusting said threshold level to detect said first and said second heart sounds of a heart cycle, means for selectively modifying the duration of said first output pulses, means responsive to the output of said pulse modifying means for producing a second output pulse of predetermined duration, the output of said second output pulse producing means being connected to the input of said comparator; means responsive to said second output pulses for producing a visual and audible indication of heart sounds; means responsive to said second output pulses for producing a signal representative of the heart rate of detected heart sounds; and means responsive to said representative signal for providing a visual digital display of said heart rate. - View Dependent Claims (18, 19, 20)
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Specification