SEMICONDUCTOR FINGERPRINT SENSING DEVICE INCLUDING SHIELDING UNIT

摘要

PURPOSE: A semiconductor fingerprint sensing device including a shielding unit is provided to detect an inherent pattern of a fingerprint using a minute difference of a fingerprint impedance according to shapes of a valley and a ridge of a fingerprint. CONSTITUTION: In a fingerprint sensing device for creating a continuous analogue fingerprint signal which reflects a fingerprint impedance(140) in each sensing point according to features of fingerprints for extracting an inherent fingerprint pattern, a plurality of sensing electrodes(130) are arranged as a matrix shape for contacting with the end of finger(valley and a ridge of fingerprint). A tristate buffer(110) supplies an electric charge to the sensing electrodes(130). A shielding unit(120) is arranged between the sensing electrode(130) and the tristate buffer(110). The shielding unit(120) blocks a transmission of a direct current to the end of a finger through the sensing electrode(130). The shielding unit(120) is an electric charge accumulating element. In addition, an initialization unit is included for maintaining an electrical characteristic of the sensing electrode(130) continuously.