Patent ID: 7379570

Claim:
An optical engine for fingerprint readers comprising a one-piece optical prism having a prism and a lens integrated with each other, and a sensing device; wherein the prism of the optical prism having an optical surface A for being pressed by a finger F, an optical surface B facing a LED light source, a first total-reflective optical surface C and a second total-reflective optical surface D; the angle between the optical surface B and the first total-reflective optical surface C is about 130° and the angle facing upwards between the optical surface A and the optical surface B is an acute angle so as to form the second total-reflective optical surface D with smaller width; while the lens of the optical prism is disposed on the position extended from the second total-reflective optical surface D and the optical surface B and a non-sphere is formed on the tail part of the lens, facing a receiving plane of the sensing device; in usage, light from the LED light source is refracted through the optical surface B and entered the optical prism, then lighting the fingerprint of the finger F pressed on the arched concave of the optical surface A while the light from fingerprint image moves toward the first total-reflective optical surface C inside the optical prism, and is reflected by the first total-reflective optical surface C, then moves toward the second total-reflective optical surface D and through a second total reflection by the second total-reflective optical surface D, then the light enters the lens and moves toward the non-sphere on the tail part of the lens and forms an image by the non-sphere and the lens; then the image is processed by the sensing device.