FINGERPRINT SENSOR OF ELECTRONIC CAPACITY METHOD FOR SUPERIOR FINGERPRINT IMAGE

摘要

A capacitance type fingerprint sensor for reinforcing a fingerprint image is provided to improve the fingerprint image to easily determine a valley/ridge of a fingerprint in case that the fingerprint image is partially dimmed by humidity present in surface of a finger while removing parasitic components. A sensing plate(101) is connected to a negative electrode of an amplifier of a detection circuit. Output of the amplifier is connected to a feedback capacitor and a switch. A shape of the fingerprint is detected by transfer of electric charge of a capacitor(201) between the sensing plate and the finger(100). The transfer of the electric charge is generated by voltage change of a positive electrode of the amplifier. The electrode for removing the parasitic component is placed between the sensing plate and a substrate(103). The parasitic component is removed by connecting the electrode to the positive electrode of the amplifier.