Automatic zeroing system and electronic level adjustment of pressure transducer applied to vital signs monitors
The present invention provides automatic zeroing and electronic level adjustment of pressure transducer in relation to patient, applied to vital signs monitors, where the automatic zeroing of circuit of pressure consists of circuit and software able to remove the value of the virtual ground voltage from the pressure calculation, and the electronic level adjustment of transducer in relation to patient consists of compensating, through software, the value in mmHg related to level difference in cmH 2 O informed by the user by means of monitor interface.
1. Automatic zeroing system and electronic level adjustment of pressure transducer applied to vital signs monitors, comprising circuit and software working together to remove the value of virtual ground voltage from a pressure calculation, and electronically adjusting the level of the pressure transducer in relation to a patient, through software for value compensation in mmHg related to level difference in cmH 2 O informed by a user by means of monitor interface through the software;
wherein said automatic zeroing system uses two differential amplifiers with inputs inverted to each other adding to said inputs the virtual ground; and wherein said automatic zeroing and the electronic adjustment at the level at the pressure transducer with respect to the patient are simultaneously performed according to the equation:
Pressure=(Value CH 1−Value CH 2)×scaleAdjustment+levelAdjustment
where:
Pressure—final pressure value calculated in mmHg;
ValueCH1—number value achieved by an analog-to-digital converter corresponding to an output signal of a first differential amplifier;
ValueCH2—number value achieved by the analog-to-digital converter corresponding to an output signal of a second differential amplifier;
scaleAdjustment—conversion factor achieved by the analog-to-digital converter in mmHg;
levelAdjustment—value in mmHg, corresponding to level difference in cmH 2 O between the patient and the pressure transducer, informed by the user through the monitor interface.
2. The system according to claim 1 , wherein said first differential amplifier provides voltages higher than the virtual ground voltage for positive pressures and said second amplifier provides voltages higher than the virtual ground voltage for negative pressures, and, in condition of zero pressure, both differential amplifiers provide a voltage equal to the virtual ground voltage.
3. The system according to claim 2 , wherein said voltages are applied to inputs of two different channels of the analog-to-digital converter.