摘要
印刷显示技术具有低成本、柔性化、可大面积生产等显著特点,是解决OLED显示产业高成本问题的有效途径。喷墨打印工艺制备发光像素前,都需要观测液滴的喷墨状况,判断喷嘴的导通性和墨水的可打印性。但是当喷嘴的驱动波形参数、墨水的流变性或喷墨打印温度改变时,会导致喷墨的液滴均匀性、体积、喷射速度等参数发生相应变化,而这些参数的变化通常无法通过肉眼去分辨。该文开展了喷墨液滴参数自动化测量技术研究,以Δt=10μs的相位延迟时间获取不同时刻的液滴图像,形成完整的喷射过程,并对每张图像进行滤波降噪、二值转换、形态学运算和边缘检测处理,获得清晰的液滴轮廓,从而实现对液滴轮廓的有效提取,并自动计算液滴的喷射速度、直径和体积参数。为优化墨水的配制,以及喷墨打印制备高质量薄膜提供了可视化工具。
[Objective]The preparation of luminescent display pixels using inkjet printing technology offers significant advantages,including low cost,flexibility,and the potential for large-scale production.This approach effectively reduces the production cost of OLED displays.The process of inkjet printing organic light-emitting layers is particularly crucial and complex.It requires designing and optimizing driving waveforms to achieve stable droplet formation without satellite points.Additionally,the printing line width and thickness must be adjusted to produce a dense and uniform thin film.Before preparing display pixels,it is essential to observe the inkjet droplets and assess their stability.However,changes in driving waveform parameters,ink ratio,or printing temperature can affect various parameters,including ink droplet uniformity,stability,volume,and injection speed—changes that are often undetectable by the naked eye.[Methods]This study investigates an automatic measurement technology for inkjet droplet parameters.A droplet-driving waveform customization module has been integrated into LabVIEW software using the NI Vision visual development module.This optimization of the droplet-driving waveform aims to achieve perfect jet droplets.The droplet image is captured using phase delay technology,which employs two control signals of the same frequency and a constant phase difference.One signal is the droplet drive signal,while the other is a square wave signal that triggers the camera and strobe light source.When the first driving waveform from the nozzle arrives,another signal is output as a pulse square wave after a delay ofΔt.At this moment,the strobe light source activates,and the camera captures an image of the ink droplet.When the nozzle continuously sprays ink droplets at a fixed frequency,Δt remains constant,resulting in multiple images captured by the camera that maintain consistency,giving the appearance that the ink droplets are stationary in the air.By varying the delay timeΔt between the two signals,the position of the ink droplets changes,allowing for the simulation of the dynamic falling process of the ink droplets.[Results]Droplet images are obtained at different times with a phase delay ofΔt=10μs,capturing a complete spraying process.The images undergo filter denoising,binary conversion,morphological operations,and edge detection to obtain clear droplet contours.The volume of the ink droplets is calculated using an integral formula,and the diameter of the droplets is further determined using the spherical volume formula.The spray speed of the droplets is calculated based on the differences in ink droplet positions across multiple frames of images.[Conclusions]This research on automatic measurement technology for inkjet droplet parameters has resulted in the development of a hardware device for droplet observation,with a software control system implemented in LabVIEW graphical programming language.Droplet images are captured at different times with a phase delay ofΔt=10μs.Each image undergoes filtering,denoising,binary conversion,morphological operations,and edge detection to obtain clear droplet contours,thereby capturing a complete spraying process.The effective extraction of droplet contours,along with the automatic calculation of droplet spraying speed,diameter,and volume parameters,provides a visualization tool for optimizing ink preparation and inkjet printing,thereby facilitating the production of high-quality films.
作者
许伟
赵杰
姚日晖
宁洪龙
彭俊彪
XU Wei;ZHAO Jie;YAO Rihui;NING Honglong;PENG Junbiao(Guangdong Basic Research Center of Excellence for Energy&Information Polymer Materials,State Key Laboratory of Luminescent Materials&Devices,School of Materials Science and Engineering,South China University of Technology,Guangzhou 510640,China)
出处
《实验技术与管理》
CAS
北大核心
2024年第10期61-66,共6页
Experimental Technology and Management
基金
国家重点研发计划项目(2022YFB3603103)
国家自然科学基金项目(62174057,22090024)
广东省自然科学基金项目(2024A1515012216,2023A1515011026)
广东省教育厅广东省普通高校重点领域专项(新一代电子信息)(2022ZDZX1002)
广东省重点领域研发计划项目(2022B0303010001)
发光材料与器件国家重点实验室自主研究课题项目(Skllmd-2024-05)
华南理工大学课程开发项目(X2CL-C9226600)。
关键词
印刷显示
喷墨打印
自动化测量
printing display
inkjet printing
automatic measurement
