PHOTOPLETHYSMOGRAPH Russian patent published in 2009 - IPC A61B5/295 A61B5/1455 

FIELD: medicine.

SUBSTANCE: invention refers to medical equipment and can be used in functional diagnostics. A photoplethysmograph accommodates a pulse generator, a light source, an amplifier, a low-pass filter and a photodetector. The amplifier comprises a lock-in selective amplifier. Additionally, the photoplethysmograph includes a synchronous demodulator, a band-pass filter, a controlled voltage-to-current converter and a pulse distributor the first output of which is connected to the control input of the controlled voltage-to-current converter and the synchronisation input of the synchronous demodulator. The second, third, fourth and fifth outputs are connected to the first, second, third and fourth synchronisation inputs of the lock-in selective amplifier respectively. Its signal input is connected to the output of the photodetector, while the output is connected to the signal input of the synchronous demodulator with its output through the low-pass filter is connected to the signal input of the controlled voltage-to-current converter and through the band-pass with the output of the photoplethysmograph. The output of the controlled voltage-to-current converter is connected to a control circuit of light source intensity.

EFFECT: improved noise immunity from artificial light source.

3 cl, 5 dwg