Patent ID: 8300902

Claim:
A method of distinguishing forged fingerprint for determining whether an object touched on a fingerprint input surface is authentic fingerprint or forged one, by acquiring a fingerprint image of the touched object, the method comprising: emitting a ray of light having a light axis at a predetermined incident angle onto the fingerprint input surface, wherein the predetermined incident angle is larger than a first threshold angle for total reflection and smaller than a second threshold angle for total reflection, the first threshold angle for total reflection being applied when the object has a reflective index of 1, and the second threshold angle for total reflection being applied when a transparent liquid is touched on the fingerprint input surface; acquiring a fingerprint image of the object which is formed by the emitted ray of light; computing an area of the acquired fingerprint image; and determining the object to be authentic fingerprint if the computed area of the fingerprint image is larger than a reference area, and determining the object to be forged one if the computed area of the fingerprint image is smaller than the reference area.