ACOUSTIC BIOMETRIC IMAGING SYSTEM WITH ACOUSTIC IMPEDANCE MATCHED OPAQUE MASKING LAYER, AND MANUFACTURING METHOD

摘要

An acoustic biometric imaging system (3) comprising:a transparent device member (11) having a first face (12a) to be touched by a finger surface of a user, and a second face (12b) opposite the first face, the transparent device member having a first acoustic impedance (Z1); a first ultrasonic transducer (5) acoustically coupled to the second face (12b) of the transparent device member(11)in a first transducer region(5)for receiving acoustic signals (SIn) conducted by the transparent device member (11) from a finger touch region (14) laterally spaced apart from the first transducer region (5), the first ultrasonic transducer(15)having a second acoustic impedance (Z2); and an opaque masking layer (18) arranged between the transparent device member (11) and the first ultrasonic transducer(15)in the first transducer region, the opaque masking layer (18) having a third acoustic impedance (Z3) between the first acoustic impedance (Z1) and the second acoustic impedance(Z2).