Fingerprint sensor based on interior optical characteristics of the finger

Abstract

SUMMARYFingerprints are widely used as a method of personal authentication because they have the best balance among authentication performance, cost, device size, and ease of use. However, conventional fingerprint sensors have problems: the quality of the fingerprint pattern is sometimes not good due to the condition of the finger surface, such as moisture or wrinkles. These problems are caused by the operating principle of the sensors. Most fingerprint sensors detect a fingerprint pattern from the presence or absence of convexities and concavities of the finger surface. To solve these problems, we have devised a new kind of fingerprint sensor, which detects a fingerprint pattern by the use of optical characteristics inside the finger. This method is based on the new scientific discovery that a layer of skin inside the finger has a transmittance distribution corresponding to the pattern of the concavities and convexities of the finger surface. Therefore, this method can detect stable fingerprint images at all times regardless of the finger surface conditions (moisture, wrinkles). In this paper, we describe the principle of a new type of fingerprint sensor and demonstrate the effectiveness of the proposed sensor by examples.

A Review of Fingerprint Sensors: Mechanism, Characteristics, and Applications

“…tissue depend on wavelength, various wavelengths penetrate to different depths, necessitating multiple light sources and two polarizers for this sensor [89]. In 2016, Baek created a fingerprint sensor based on the modification of the optical path [90] that enables the detection of wet fingerprints.…”

“…Figure 3 d depicts a multispectral light source for detecting fingerprint pictures on the surface and within the fingerprint [ 88 ]. Because the transmission qualities of biological tissue depend on wavelength, various wavelengths penetrate to different depths, necessitating multiple light sources and two polarizers for this sensor [ 89 ]. In 2016, Baek created a fingerprint sensor based on the modification of the optical path [ 90 ] that enables the detection of wet fingerprints.…”

“… Many optical fingerprint sensor designs. ( a ) The principle of the whole internal reflection technique; ( b ) the principle of the light-path separation method; ( c ) the principle of the in-finger light dispersion method; ( d ) the principle of the multispectral method [ 89 ]. …”

“…( c ) Fingerprint images of a wrinkled finger and the OCT image. ( d ) Almost flat finger image and the optical coherence tomography (OTC) image [ 89 ]. ( e ) Construction of equipment, ( f ) structure of subsurface fingerprints, ( g ) different layers of subsurface fingerprint, and ( g – k ) different fingerprint images.…”