Patent ID: 8483805

Claim:
A vessel pulse wave measurement system that performs vessel pulse wave measurement using an optical probe circuit, the optical probe circuit comprising: an optical probe configured to include a light emitting element that radiates light to a blood vessel through a skin, and a light receiving element that receives, through the skin, reflected light from the blood vessel or transmitted light through the blood vessel; a drive circuit that drives the light emitting element based on an inputted drive signal; and a detection circuit that converts the light received by the light receiving element into an electrical signal and outputs the electrical signal, wherein the vessel pulse wave measurement system comprises: a measurement device configured to directly and synchronously feed back the electrical signal to the drive circuit as the drive signal, generate a self-oscillation signal from the detection circuit, and measure the self-oscillation signal as a vessel pulse wave signal; and a controller configured to control an operating point of at least one of the detection circuit and the drive circuit such that the self-oscillation signal substantially reaches a maximum level thereof; wherein the measurement device further includes a pressure sheet sensor provided between the optical probe circuit and a pressing portion provided on the optical probe circuit, wherein the measurement device further includes a calibration part, and wherein, when the vessel pulse wave signal is measured and a stress is applied to the optical probe circuit on the blood vessel by pressure applied to the pressing portion by a pressure actuator or by pressure applied to the pressing portion by a human and then the vessel pulse wave signal is not measured any more, the calibration part stores a voltage value of the vessel pulse wave signal obtained immediately before the vessel pulse wave signal is not measured, as a maximum blood pressure value voltage, the calibration part stores a detected pressure value of the pressure sheet sensor as a maximum blood pressure value, then, when the vessel pulse wave signal is measured by reducing the pressure, the calibration part stores a voltage value of the vessel pulse wave signal obtained immediately after the vessel pulse wave signal is measured, as a minimum blood pressure value voltage, the calibration part stores a detected pressure value of the pressure sheet sensor as a minimum blood pressure value, and the calibration part creates a conversion equation representing conversion from a blood pressure value voltage to a blood pressure value, based on the stored maximum blood pressure value voltage and maximum blood pressure value corresponding to the stored maximum blood pressure value voltage, and the stored minimum blood pressure value voltage and minimum blood pressure value corresponding to the stored minimum blood pressure value voltage, thereby performing calibration to convert a blood pressure value voltage of the vessel pulse wave signal to a blood pressure value, using the conversion equation.