Patent ID: 7064743

Claim:
A finger movement detection method comprising: detecting a fingerprint in an area smaller than a fingertip to obtain a first sensor image and a second sensor image; pattern matching by extracting a plurality of partial image areas of the obtained second sensor image as small blocks, searching for an image area having a fingerprint pattern that agrees with a fingerprint pattern in one of the small blocks of the second sensor image from the first sensor image, and obtaining a plurality of vectors indicating a movement of a finger, based on a plurality of displacements of the small blocks in the second sensor image from the image areas in the first sensor image; selecting a vector having a highest matching degree from the plurality of vectors as a vector indicating the finger movement, when a fingerprint image in the first sensor image and a fingerprint image in the second sensor image are superimposed on each other based on the respective vectors; and correcting a combined vector to a vector indicating the finger movement, the combined vector being obtained by combining a mean vector between a vector that is obtained by multiplying a newly selected vector by a first coefficient and a vector that is previously obtained by being multiplied by the first coefficient, with a vector obtained by multiplying a previously combined vector by a second coefficient.