Shin Dong Yeol, Moon Yoon Jae, Ju Byeong-Kwon, Kang Kyung-Tae
Micro/Nano System Department, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, Korea.
Autonomous Manufacturing & Process R&D Department, Korea Institute of Industrial Technology (KITECH), Sangnok-gu, Ansan-si, 15588, Korea.
Sci Rep. 2024 Sep 27;14(1):22364. doi: 10.1038/s41598-024-71952-9.
Inkjet printers are key technologies in manufacturing organic light-emitting diodes and quantum dot light-emitting diode panels, but precise measurement and control of inkjet droplets remains challenging. The international standard, IEC 62899-302-1, uses shadow image-based measurement with high magnification microscopes to observe picoliter-sized droplets. However, high magnification lens results in a shallow depth of field or narrow optimal measurement area, causing the blurring image if the droplet does not pass through the optimal measurement area. To solve this, we propose using the interference image-based measurement with interference fringe patterns by inkjet droplets as a tool to measure the flight speed of droplets. The interference fringe patterns can be obtained simply passing the droplet through within the light beam path, providing approximately 1000× wider measurement area compared to the shadow image-based measurement, making it practical to use in the industry. The flight speed of droplets analyzed with the interference image-based measurement at various frequencies and amplitudes of the inkjet driving voltage were compared with the shadow image-based measurement. The interference image-based measurement showed a coefficient of variation of less than 3%, showing higher repeatability than the shadow image-based measurements.
喷墨打印机是制造有机发光二极管和量子点发光二极管面板的关键技术，但对喷墨液滴进行精确测量和控制仍然具有挑战性。国际标准IEC 62899-302-1采用基于阴影图像的测量方法，使用高倍显微镜来观察皮升大小的液滴。然而，高倍镜头会导致景深较浅或最佳测量区域狭窄，如果液滴未通过最佳测量区域，就会造成图像模糊。为了解决这个问题，我们提出使用基于干涉图像的测量方法，利用喷墨液滴产生的干涉条纹图案作为测量液滴飞行速度的工具。通过使液滴在光束路径内通过，即可简单地获得干涉条纹图案，与基于阴影图像的测量相比，其测量区域宽约1000倍，使其在工业中具有实际应用价值。将基于干涉图像测量在不同喷墨驱动电压频率和幅度下分析得到的液滴飞行速度与基于阴影图像的测量结果进行了比较。基于干涉图像的测量显示变异系数小于3%，比基于阴影图像的测量具有更高的重复性。
