Research On Modeling And Allocation Method Of Ink Droplet Positioning Error For Inkjet Printing Patterning

Organic light-emitting displays(OLED)have been widely concerned in recent years due to its advantages of light weight,wide viewing angle,fast picture response,low energy consumption and flexible processing.The device structure is a multilayer film structure composed of a hole injection layer,a light emitting layer,an electron transport layer,and the like.In manufacturing technology of key function layer,compared with fine metal mask and atomic layer deposition,inkjet printing has the characteristics of maskless patterning approaches,high material utilization,simple process and low cost,and is considered to be one of the most potential technologies for producing large-size and high-resolution OLED panels.The ink droplet positioning error control of RGB ink droplets in the light emitting layer is the key technology in the multi-axis inkjet printing system for producing OLED panels.The ink droplet positioning error refers to the difference of the positioning error between the print head and the substrate in the printing system.This paper focuses on the error modeling,sensitivity analysis and error allocation of ink droplet positioning error in the multi-axis inkjet printing system,which mainly includes:(1)An ink droplet positioning error model in the multi-axis inkjet printing system is established based on the multi-body system theory and homogeneous transformation matrix.The multi-axis inkjet printing system is abstracted as the topological structure of multi-body system,and the adjacent bodies in the topological structure are described with the low-order volume array,and then the characteristic matrix of motion error between any two adjacent bodies in the ideal and actual case is inferred by homogeneous transformation matrix,and finally the ink droplet positioning error model is obtained.(2)The global maximum interval sensitivity of each error is derived by the sensitivity analysis of different position and angle errors in the multi-axis inkjet printing system.Based on the ink droplet positioning error model,different position and angle errors are processed by interval theory.The error sensitivity analysis of the ink droplet positioning error model is performed by direct matrix differential method,which provides the error allocation weights for the subsequent error allocation of ink droplet positioning.(3)A method for the error allocation of ink droplet positioning is proposed.The allocation model of ink droplet positioning error is established with the interval width of each error as the design variable,the ink droplet positioning error in X and Y directions not exceeding the allowable error range as the constraint,the global maximum interval sensitivity of each error as allocation weights and maximizing the interval width of each error as the design goal.(4)The proposed modeling and allocation method of ink droplet positioning are verified by simulation of the inkjet printing patterning experiment platform built by our research group.Firstly,the ink droplet positioning error model is established,and the allocation model of ink droplet positioning error is derived,then the allocation model of error is solved to obtain the maximum allowable error range.The qualified rate of the ink droplet positioning error is obtained by the error model when the 21 errors of the inkjet printing patterning experiment platform are the maximum value and the interval value respectively,which verifies the feasibility of the modeling and allocation method of ink droplet positioning error in this paper.In this paper,the modeling and allocation method of ink droplet positioning error in the inkjet printing patterning process for producing OLED panels is proposed.Under the condition of ensuring that the ink droplet positioning error does not exceed a certain range,the influence of different errors on the ink droplet positioning error is analyzed,and then the allowable range of different errors in the multi-axis inkjet printing system is obtained.In the design and manufacturing process of multi-axis inkjet printing system with different sizes of OLED panels,this paper provides a certain reference significance for the modeling and allocation of ink droplet positioning error,so as to control the ink droplet positioning error and printing system cost.