Looking for breakthrough ideas for innovation challenges? Try Patsnap Eureka!

Fingerprint identification system based on raster structure and microprism array

A technology of fingerprint identification and grating structure, which is applied in the direction of prism, diffraction grating, character and pattern recognition, etc. It can solve the problems of difficult miniaturization, difficult miniaturization, and large overall structure, so as to increase the contrast of fingerprint images and reduce finger scattering The effect of precise optical path control

Active Publication Date: 2016-07-13
SHANGHAI JIAO TONG UNIV
View PDF6 Cites 19 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The traditional optical fingerprint recognition system generally has three disadvantages: the structure is bulky and difficult to miniaturize; the optical path is greatly affected by the diffuse reflection of fingers, and the imaging quality is not high; the sliding fingerprint scanning method is used, and the user experience is poor
U.S. Patent US5177802 discloses a structure that uses prisms to read fingerprint images. However, due to the use of prisms, this structure is difficult to miniaturize and cannot be used in mobile terminals such as smart phones and tablet computers.
Chinese patent CN1820272A discloses a system that uses an optical waveguide structure to realize fingerprint image reading, but the optical path of this structure is relatively rough, the imaging quality is poor, and the optical waveguide structure is relatively thick, making it difficult to achieve ultra-thinning
U.S. Patent US6259108B1 discloses a structure that uses a linear array image sensor for sliding fingerprint scanning, but the overall structure is large and difficult to miniaturize
Chinese patent CN104751121A discloses an optical waveguide fingerprint recognition system based on a grating structure, but the contrast of the fingerprint image is not high, and it is not light enough

Method used

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Image

Smart Image Click on the blue labels to locate them in the text.
Viewing Examples
Smart Image
  • Fingerprint identification system based on raster structure and microprism array
  • Fingerprint identification system based on raster structure and microprism array
  • Fingerprint identification system based on raster structure and microprism array

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0060] From formula (5), we can see that, In order to get a smaller thickness h, in L 1 Under certain circumstances, the closer the diffraction angle j should be set to 90°, the better. Combining with formula (2), considering the lateral propagation, the diffraction angle j should be set to 85°θ 1 is 5°, the corresponding grating period is 370nm, and the incident light wavelength is 550nm. For the case of air normal incidence, the air refractive index n 0 =1, the waveguide material is the most commonly used polymethyl methacrylate, its refractive index n 1 = 1.49, the refractive index of the finger surface is about 1.39-1.42, combined with formula (13), it can be obtained that 16.11° Figure 5 As shown, the illuminance of valley lines in the fingerprint pattern received by the imaging device is close to 0, and the contrast is close to 95%. As the angle increases, the fingerprint pattern appears slightly blurred, and the contrast ratio drops to 89%. This is because the small...

Embodiment 2

[0062] For the case of air normal incidence, the air refractive index n 0 =1, waveguide refractive index n 1 =1.49, the refractive index of the finger surface is about 1.39~1.42, set θ=25°, the diffraction angle j is 85°, θ 1 If it is set to 5°, when the unit width d of the microprism is different, the obtained fingerprint patterns are also different. Using software simulation to simulate the width of the triangle base of different microprism sections, the results are as follows Figure 6 shown. It is ideal for the case of d=0.05mm. When d is larger than 0.1mm, due to the increase of the width of the bottom edge, the depth of the prism section will increase under the condition of a certain angle θ, which makes it more difficult for fingers to touch, so the fingerprint pattern Streaks will appear. Therefore, for the selection of the unit width d of the microprism, the smaller the better, but considering the limitation of the processing technology, d=0.05mm is more suitable. ...

Embodiment 3

[0064] For the case of air normal incidence, the air refractive index n 0 =1, waveguide refractive index n 1 =1.49, the refractive index of the finger surface is about 1.39, set θ=25°, the diffraction angle j is 85°, d is 0.05mm, when θ 1 When the settings are different, the obtained fingerprint patterns are also slightly different, such as Figure 7 As shown, if θ 1 When the smaller is 1°, then θ 1 The side of the prism where it is located will reflect part of the light, thus reducing the useful light and reducing the contrast of the image; if θ 1 When the maximum is 35°, the fingerprint detection area is more rugged, and the finger is not easy to touch the bottom of the microprism, thus reducing the image contrast and user experience; when θ 1 When it is 5°, the ruggedness is appropriate, and a high-contrast and clear fingerprint pattern is obtained.

[0065] Experiments show that the present invention utilizes the diffraction of the grating, the light of the light sour...

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

PUM

No PUM Login to View More

Abstract

Provided is a fingerprint identification system based on a raster structure and a microprism array, comprising a light source, an optical waveguide, a microprism array, a raster, a fingerprint detection area and an image device. The system employs a raster structure on the optical path of a light source entering the optical waveguide, allowing the light emitted by the light source to be diffracted by the raster and then propagate horizontally in the optical waveguide so as to form fingerprint detection light, and controls a raster period to avoid overlapping between a fingerprint identification area and a raster area, thereby guaranteeing the signal to noise ratio of a fingerprint graph; in order to more easily damage the total reflection of the fingerprint identification area, the surface of the optical waveguide is provided with a microstructure of a specific shape to change the normal direction of a total reflection surface, thereby substantially increasing a signal to noise ratio of a fingerprint image, meanwhile greatly reducing the thickness of the optical waveguide, and realizing a miniature and ultra-thin system.

Description

technical field [0001] The invention relates to the technical field of optical fingerprint imaging, in particular to a fingerprint identification system based on a grating structure and a microprism array. Background technique [0002] Fingerprint identification technology can be classified into three categories: optical, capacitive, and radio frequency, according to the way of fingerprint image collection. When the finger touches, the corresponding sensor detects the corresponding physical quantity and converts it into an electrical quantity to form a fingerprint image for comparison and identification. [0003] The biological radio frequency method transmits a small amount of radio frequency signal through the sensor, penetrates the skin layer of the finger to obtain the texture information of the inner layer, the energy loss of the radio frequency signal caused by the ridges and valleys of the finger fingerprint is different, and the receiver forms a fingerprint image thr...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

Application Information

Patent Timeline
no application Login to View More
IPC IPC(8): G02B5/18G02B5/04G02B27/42G06K9/00
CPCG02B27/4205G02B5/045G02B5/1842G06V40/1324
Inventor 叶志成马萍
Owner SHANGHAI JIAO TONG UNIV
Who we serve
  • R&D Engineer
  • R&D Manager
  • IP Professional
Why Patsnap Eureka
  • Industry Leading Data Capabilities
  • Powerful AI technology
  • Patent DNA Extraction
Social media
Patsnap Eureka Blog
Learn More
PatSnap group products

Browse by: Latest US Patents, China's latest patents, Technical Efficacy Thesaurus, Application Domain, Technology Topic, Popular Technical Reports.

© 2024 PatSnap. All rights reserved.Legal|Privacy policy|Modern Slavery Act Transparency Statement|Sitemap|About US| Contact US: help@patsnap.com