Design And Experimental Study Of Piezoelectric Flexible Braille Contacts Based On Air Pressure Amplification

Braille dot display,also known as Braille terminal,Braille display machine,converts text information in the computer into Braille and displays it synchronously through Braille dot display,so that blind people can realize human-computer interaction with the computer in the process of touching and reading,which is convenient for blind people to read.Nowadays,the new era of Internet information technology has enriched people’s life with diversified information,but for the special people with visual impairment,the information resources they can access are relatively limited and lagging,so how to develop a light and portable,fast response,energy-saving and efficient Braille braille display has become a popular research problem to be solved.This paper is based on the project of the National Natural Science Foundation of China(NSFC)"Theoretical design and key technology research of piezoelectric driven gas flexible actuator(51705031)" and the project of the Natural Science Foundation of Jilin Provincial Science and Technology Department(20200201063JC)"Theoretical design and key technology research of piezoelectric driven liquid flexible Braille dot displayer".20200201063JC),proposed a piezoelectric flexible Braille contact structure based on air pressure amplification(hereinafter referred to as "piezoelectric flexible Braille contact"),conducted an in-depth and systematic investigation into the theory of piezoelectric flexible Braille contact,designed and fabricated a prototype of piezoelectric flexible Braille contact,and conducted a study on the design of piezoelectric flexible Braille contact.The prototype of piezoelectric flexible Braille contact was designed and fabricated,and the related piezoelectric oscillator theory,piezoelectric flexible Braille contact structure design,gas-solid coupling simulation analysis and experimental research were carried out.The main research contents are as follows.1.Through reading a large number of domestic and foreign related literature,the research background and significance of Braille dot display development,Braille composition and the current situation of domestic and foreign development were analyzed,and a new piezoelectric flexible Braille contact structure was proposed on the basis of the progress of previous research.2.Using circular piezoelectric oscillator as the driving force source of piezoelectric flexible Braille contact structure,the vibration theory and modal simulation analysis of the piezoelectric oscillator are carried out by using the thin plate theory of elasticity mechanics,and the displacement change of the center point of circular piezoelectric oscillator and its impedance characteristics are tested by using high-precision laser displacement meter and precision impedance analyzer,and the vibration theory of circular piezoelectric oscillator is verified in both directions by combining experiment and theory.3.Design and optimization of the structure of the piezoelectric flexible Braille contact,including the selection and performance analysis of the piezoelectric flexible material and the design of the air cavity,housing and contact structure.4.The structure of the piezoelectric flexible Braille contact is systematically analyzed,and the electromechanical coupling characteristics of the piezoelectric oscillator are analyzed from the material instanton equation of the piezoelectric oscillator,and the Lagrangian equation of electromechanical energy transformation of the piezoelectric oscillator is derived.Then,the equivalent rigid body theory is introduced to analyze the mechanism of the piezoelectric amplification system and carry out gas-solid coupling simulation analysis for the whole system,and explore the influence of different gas media on the performance of the whole system by replacing different gas media in the cavity.5.The actual prototype was fabricated according to the designed structure,and the theoretical basis was combined with practical tests to investigate the effects of parameters such as air cavity diameter,air cavity height,flexible film thickness,contact hole shape and contact height on the displacement output of the piezoelectric flexible Braille contact.The maximum output displacement of the piezoelectric flexible Braille contact is 0.286 mm when the diameter of the air cavity is 24 mm,the height is 6 mm,the thickness of the flexible film is 0.1 mm,the contact height is 2 mm,the input voltage is 135 V,and the resonance frequency reaches 196.5 Hz.The maximum output displacement of the piezoelectric flexible Braille contact is 0.286 mm,which meets the output displacement requirement of Braille contact in the national standard,and can effectively form dynamic stimulation in the resonant state of the system to realize the Braille dot display function.