A FINGERPRINT SENSING SYSTEM USING A SHEET PRISM

摘要

A fingerprint sensing system (200) includes a sheet prism (100) having a sensing surface (102) and a number of prismlets positioned opposite to the sensing surface. Each prismlet has an entrance surface and an exit surface, and is adjacent to another prismlet. When a finger is positioned on the sensing surface, a portion of the radiation entering a number of the entrance surfaces and incident at the sensing surface is reflected through total internal reflection. The reflected radiation emits from a number of the exit surfaces to create an image of the fingerprint.