Patent ID: 8758259

Claim:
An apparatus for measuring pulse waves, comprising: a pulse wave detection unit configured to detect pulse waves of a subject; an amplitude detection unit configured to detect a plurality of amplitudes of the pulse waves; an interval detection unit configured to detect an interval of time between two of the pulse waves, the two being adjacent along a time axis; and a decision unit configured to calculate a first change ratio and a second change ratio, compare the first change ratio with a first threshold, and, when the first change ratio is larger than the first threshold, decide whether the pulse waves represent arrhythmia by comparing the second change ratio with a second threshold, wherein the first change ratio is a ratio of a difference between the interval and a previous interval to the previous interval, the second change ratio is a ratio of a difference between the amplitude divided by the interval and a previous amplitude divided by the previous interval to the previous amplitude divided by the previous interval, wherein the interval detection unit detects a maximum and a minimum of each pulse wave in a predetermined period along the time axis, calculates an internally dividing point between the maximum and the minimum at a predetermined ratio, detects a time at an intersecting point of the internally dividing point and each pulse wave, and calculates the interval as a difference between the time at the intersecting point and a time at a previous intersecting point, and the amplitude detection unit calculates the amplitude as a difference between the maximum and the minimum.