Abstract There is described a diagnostic system for measuring the frequency of a patient''s heartbeat which automatically protects against erroneous low readings resulting from abnormally high heartbeat frequencies. An input transducer monitors the patient''s electrocardiac signal and develops an amplified electrical signal representative thereof. A monostable multivibrator is responsive to this amplified signal to produce an output signal consisting of a series of pulses having a uniform amplitude and width and having a repetition rate representative of the heartbeat frequency. The pulse series is converted into a DC voltage, proportional to the repetition rate, by a frequency-to-voltage converter. A readout device in the form of a voltmeter is responsive to the DC voltage to provide a visual indication of the patient''s heartbeat frequency. The output signal of the multivibrator is subject to erroneous low values resulting from abnormally high heartbeat frequencies having periods shorter than the pulse width of the multivibrator. To overcome this deficiency, an additional amplifier circuit is employed which is responsive to the repetition rate of the multivibrator output signal for effecting variations in the multivibrator timing circuit to maintain its pulse width shorter than the heartbeat period regardless of variations in the patient''s heartbeat frequency. This prevents the erroneous low values in the multivibrator output signal and thereby precludes erroneous heartbeat frequency readings resulting therefrom.
A diagnostic system for measuring the frequency of a patient''s heartbeat, including means for protecting against erroneous low readings resulting from abnormally high heartbeat frequencies, comprising: an input transducer for monitoring the patient''s heartbeat and developing an electrical signal representative thereof; generator means responsive to said electrical signal for producing a series of pulses having a uniform amplitude and width, and having a repetition rate representative of said heartbeat frequency; signal converter means responsive to said pulse series for generating a control signal proportional to said repetition rate, said control signal being subject to erroneous low values resulting from abnormally high heartbeat frequencies having periods shorter than said pulse width; output transducer means responsive to said control signal for providing an indication of the patient''s heartbeat frequency; and means responsive to said control signal for effecting variations in said pulse width to maintain said pulse width shorter than said heartbeat period regardless of variations in the patient''s heartbeat frequency, in order to prevent said erroneous low values and preclude erroneous heartbeat frequency readings resulting therefrom.
Claim 2
Dependent Claim
175 words
A diagnostic system for measuring the frequency of a patient''s heartbeat, including means for protecting against erroneous low readings resulting from abnormally high heartbeat frequencies, comprising: an input transducer for monitoring the patient''s heartbeat and developing an electrical signal representative thereof; generator means responsive to said electrical signal for producing a series of pulses having a uniform amplitude and width, and having a repetition rate representative of said heartbeat frequency; signal converter means responsive to said pulse series for generating a control signal proportional to said repetition rate, said control signal being subject to erroneous low values resulting from abnormally high heartbeat frequencies having periods shorter than said pulse width; output transducer means responsive to said control signal for providing an indication of the patient''s heartbeat frequency; and means responsive to said control signal for effecting variations in said pulse width to maintain said pulse width shorter than said heartbeat period regardless of variations in the patient''s heartbeat frequency, in order to prevent said erroneous low values and preclude erroneous heartbeat frequency readings resulting therefrom.
Claim 3
Dependent Claim
46 words
A diagnostic system according to claim 1, in which said generator means comprises a monostable multivibrator having a timing network for determining the length of time that said multivibrator is turned on, and responsive to said control signal for effecting variations in said length of time.
Claim 4
Dependent Claim
31 words
A diagnostic system according to claim 1, in which said pulse width variation means includes a threshold detector effective only when said control signal attains or exceeds a predetermined threshold level.