Design Of Power Drive System For Piezoelectric Micro-droplet Printhead

The flexible preparation of circuit on fabric surface is the key to the integration of electronic components on smart textiles.At present,there are shortcomings of existing fabric circuit preparation methods,such as high cost,unbending,uneasy washing and complex craftsmanship.A new method to manufacture the circuit by combing micro-droplet jetting with chemical deposition technology is proposed in this paper.The micro-droplet controllable and on-demand jetting is the precondition of high-quality circuit.Piezoelectric jet technology is an effective injection method and has advantages such as high frequency of injection,exact controllability.The printhead power is an important part of piezoelectric jet system,which should supply controllable voltage to charge and discharge the piezoelectric ceramics.This process causes high current consumption.In order to solve this problem,a power drive system of piezoelectric micro-droplet printhead was designed in this paper.The system exported digital drive signal by using FPGA system and STM32 system.By using signal amplification circuit which was composed of operational amplifiers,the digital drive signal was magnified linearly,the drive voltage was produced in the end to control the vibration of piezoelectric ceramics.The main contents are listed as follows:(1)General structure design of power drive system for piezoelectric micro-droplet printhead.Aiming at the function of drive system for piezoelectric printhead,by amplifying the digital drive signal linearly,the power drive system was developed.The way of generation method for trapezoidal wave was designed based on FPGA system to overcoming the shortcomings of DDS method.General structure design of power drive system for piezoelectric printhead was finished in the end.(2)Hardware circuit design of power drive system.STM32 system、FPGA system and D/A conversion circuit composed of AD9764 and AD829 was designed to create digital drive signal.The stability of power amplifier composed of PA85 and OPA627 was analyzed in detail in this paper,it was also verified through computer simulation.(3)Software design of power drive system.The software of STM32 system and the logical circuit of FPGA system was designed in this paper.The PC interface design was finished based on LABVIEW.The logical circuit based on FPGA system exported adjustable digital drive signal,including rising edge、falling edge、high time and frequency.The software based on STM32 system was designed to feedback the voltage.(4)The overall performance of power drive system.The parameters of drive signal was imported in the PC interface.The drive signal was collected by using oscilloscope,its frequency ranged from 1Hz to 40 k Hz,its rising edge changed among 10μs,its high time was controllable,its voltage changed among 0.67-4.5V,the tests verified the digital control functions of the power drive system for piezoelectric micro-droplet printhead.By connecting the drive signal with 1V voltage and 1.5μs rising edge into the Power drive circuit board,the drive voltage was displayed with 2.35μs rising edge and the offset voltage was 2.3%.