Optical Touch Screen Integrated With Fingerprint Recognition

Intelligent electronic devices are an essential part of human life.With the development of artificial intelligence,people's requirements for convenience and security are also constantly increasing.Accompanying the importance of individuals,biometrics is rapidly evolving,and even full of all aspects of our lives,a simple scene such as: early morning,voice recognition to help you turn off the alarm;face recognition to help you brush face punch;work Fingerprinting helps unlock your phone...As you can see,there are numerous applications of biometrics in the display of touch devices,especially the portable smart touch devices equipped with fingerprint recognition are helping people to improve their production and living standards and ensure financial privacy information.However,commonly used smart devices,fingerprint sensors and display touch screen are independent of each other,which makes the use of the process greatly reduce the security and convenience.The reason for this phenomenon is that fingerprints and touch sensors vary greatly in sensing resolution and transparency requirements.In the current common capacitive fingerprint recognition technology,you can guarantee a higher image resolution,but can not be fully transparent requirements.The capacitive touch screen technology requires greater transmittance,while the sensing resolution is not demanding.This contradiction makes the two have difficulties in integration.With its inherently high transparency,optical touch screens have gained a lot of attention in the industry.However,optical fingerprint recognition technology is not suitable for direct integration in portable smart devices because of its size.According to the present situation of contradictions in the industry,this dissertation innovatively proposes and verifies the integrated touch and fingerprint identification screen based on nano-gratings.Firstly,this thesis explores the principle of various touch screens and fingerprinting techniques.Based on the accumulation of nanog rasters in our laboratory,we propose using nanog rasters for both touch and fingerprinting.Based on this,we use Light Tools ray tracing The software preliminarily simulates the proposed design scheme and concludes that both the fingerprint and the touch position can be extracted at the same time.Then,the finite element method in time domain is used to further optimize and analyze the key element-grating.The optimal grating height,duty cycle,tilt angle and period are respectively calculated and used to guide the experiment.In the experimental phase,this dissertation firstly made a grating master by laser interference exposure method,and then a series of operations such as metal coating,die-plate transfer and nano-hot embossing were carried out on the master.The master grating was transferred to a flexible,Transparency,toughness,hardness of the PC board.The thesis also tests the efficiency of the grating produced,which proves to be in good agreement with the experimental results.By assembling the image sensor and the silicon photodetector,the original fingerprint image and the light intensity information are respectively obtained from the two detectors,and the fingerprint preprocessing image and the touch position coordinate that can be used for identification are further analyzed.This study designs,builds,and verifies an optical fingerprint recognition and touch screen integration technology based on Nano gratings.