Slot die coating is a versatile coating method which has been used widely in large display industry. In slot die coating, one of the coating qualities is coating uniformity. To evaluate the coating uniformity, a method of directly measuring the thickn...
Slot die coating is a versatile coating method which has been used widely in large display industry. In slot die coating, one of the coating qualities is coating uniformity. To evaluate the coating uniformity, a method of directly measuring the thickness of the coating after drying of the coating solution is mainly used. However, this method consumes a lot of time and cost, and uncertainty may occur when drying the coating solution. In this paper, the coating uniformity is estimated simply by measuring the flow rate discharged from the slot die nozzle. This method can be a quick evaluation for machine direction uniformity. Using a precision weighing cell, the amount of discharged fluid is weighed and monitored. From the weight data, the flow rate is estimated using filters or wavelet data processing. For verification, a prototype was manufactured using a lab-made precision weighing cell, a syringe pump and a needle nozzle. The validity of the proposed method was confirmed through experiments for various constant flow rates and fluctuated flow rates.