AMBIENT LIGHT AUTO-ZERO CIRCUIT FOR PHOTO-OPTICAL PHYSIOLOGICAL MONITORING EQUIPMENT

摘要

A power reduction circuit for photo-optical physiological monitoring equipment adapted to measure a physiological property of a patient by illuminating a portion of the patient with one or more light sources producing a modified light signal which is detected by a photo-sensor, generating a raw output signal which includes an ambient light component, characterized in that the power reduction circuit includes: ii. An adding unit that produces a processed signal by adding the raw output signal to a second signal; ii a first signal buffer to store the processed signal; iii a processing unit; iv an isolating switch to control a feed back circuit; v an inverting amplifier, which amplifies and inverts a stored processed signal generating the second signal; such that the processed signal generated when the isolating switch is open, during the measurement of the desired physiological property, is effectively free of the ambient light component.