Optical sensor device for detecting a pulse of a living body

摘要

An optical sensor device includes a light emitter for emitting, to a living body, lights having two wavelengths and blinking at a predetermined frequency, and a light receiver for receiving the lights from the living body. The light receiver outputs first and second detection signals corresponding to the respective wavelengths. A filter circuit extracts, from the first and second detection signals, modulation signals that are obtained with amplitude modulation of signals of the predetermined frequency. The modulation signals are amplified by a post-amplifier and are taken into an arithmetic processing unit after being converted to digital signals by an AD converter. The arithmetic processing unit calculates DC components and AC components of the first and second detection signals by employing the modulation signals converted the digital signals.

主权项

1. An optical sensor device comprising:
a light emitter configured to periodically emit light at a predetermined frequency toward a measurement target; a light receiver configured to detect at least one of reflected light and diffused light from the measurement target, and to output an electrical signal based on the detected light; a filter circuit configured to filter the electrical signal at the predetermined frequency and to output a modulation signal; an amplifier configured to amplify the modulation signal; an AD converter configured to convert the modulation signal to a digital signal; and an arithmetic processing unit coupled to the AD converter and configured to calculate a DC component of the electrical signal based on the digital signal by:
calculating a total DC component based on both extraneous light noise and the detected light by employing a signal contained in the modulation signal and obtained during an on-period of the light emitter,calculating a DC component attributable to the extraneous light noise by employing a signal contained in the modulation signal and obtained during an off-period of the light emitter, andcalculating the DC component attributable to the detected light by excluding the DC component attributable to the extraneous light noise from the calculated total DC component, wherein the arithmetic processing unit is further configured to calculate an AC component of the electrical signal by excluding the DC component from the modulation signal.