Patent 7366332 was granted and assigned to Nippon Telegraph and Telephone on April, 2008 by the United States Patent and Trademark Office.
A detection element (1A) having a detection electrode (11A) connected to a surface shape detection unit (2) and a detection electrode (12A) connected to a common potential, and a detection element (1B) having a detection electrode (11B) connected to the surface shape detection unit (2) and a detection electrode (12B) connected to a biometric recognition unit (3) are arranged. The surface shape detection unit (2) outputs a signal representing the three-dimensional pattern of the surface shape corresponding to the contact portion to each detection element on the basis of individual capacitances obtained from the detection elements (1A, 1B). The biometric recognition unit (3) determines whether an object (9) is a living body, on the basis of a signal corresponding to the impedance of the object (9) connected between the detection electrode (12B) of the detection element (1B) and the detection electrode (12A) of the detection element (1A).