Patent ID: 8715197

Claim:
A blood pressure information measurement device for measuring blood pressure information by detecting a volume of an artery, comprising: a cuff to be wound around a predetermined measuring site; an adjustment unit that adjusts pressure in the cuff by pressurization and depressurization; a pressure detector that detects cuff pressure representing the pressure in the cuff; a volume detector arranged at a predetermined position of the cuff, wherein the volume detector detects an artery volume signal indicating the volume of the artery; and a control unit that controls measurement of the blood pressure information by performing servo-control on the adjustment unit so that the volume of the artery is constant, wherein the control unit includes a detection processing unit that detects a control target value in the servo-control based on the artery volume signal, and wherein the detection processing unit comprises: an adjustment control unit that instantaneously changes the cuff pressure in a specified pressure range by controlling the adjustment unit; and a decision unit that detects an inflection point of the artery volume signal obtained in a control period of the adjustment control unit and decides the control target value with using the detected inflection point, wherein the decision unit comprises a differentiation unit that differentiates the artery volume signal, so that when the differentiation unit produces a maximum differential value, the inflection point is detected.