Study on Manufacturing Process Optimizing of Lightguiding Plate for Soft Computing

This paper discusses the research of optimal process for lightguiding plate of backlight module of liquid crystal display. The PMMA material was used on lightguiding plate. This paper indicates that the different processing parameters (mold temperature, injection temperature, first period injection speed, second period injection speed, third period injection speed, packing pressure and packing time) are important for optimal research for lightguiding plate of backlight module. This paper introduces the extension engineering, simulated annealing and genetic algorithm on soft computing for optimal process and compares the results with experiment. The results show that the optimal process group is A1 B1C2 D3 E2 F2 G3 for extension engineering, simulated annealing, genetic algorithm or experiment. The mold temperature is the most important processing parameter of the flatness of lightguiding plate for soft computing and experiment. The calculation times for extension engineering, simulated annealing and genetic algorithm are less than experiment’s time. Introduction Lightguiding plate is the most important part for the liquid crystal display (LCD). Shen et. al.,[1] discussed the melt front delay of lightguiding plate as the filling stage of injection molding. Shi et. al., [2] used the soft computing method to find the optimization of plastic injection molding process. This paper uses the lightguiding plate of LCD as an example to compare the results of experiment with results of soft computing. Experimental approaches This paper uses the lightguiding plate as an example to discuss the results for experiment and soft computing. The objection function is the flatness of lightguiding plate of LCD. The dimensions of lightguiding plate are shown on Fig.1. In this paper, author uses different processing parameters (mold temperature, injection temperature, first period injection speed, second period injection speed, third period injection speed, packing pressure and packing time) to discuss the properties of lightguiding plate. Because the parameters and levels have many values, the author introduces the Taguchi method to find the optimal result. There are seven parameters and three levels in this study, so the author uses the L18 orthogonal array table. Table 1 shows that the parameters and levels for this research. This research uses the injection molding machine (CLF-1257) to fabricate the lightguiding plate of LCD. After the experiment had done, this research also uses the CMM (CHZEN WEI CE-607) to measure the flatness of lightguiding plate. The mold temperature chooses the smallest value, the injection temperature chooses the smallest value, the first period injection speed chooses the middle value, the second period injection speed chooses the biggest value, the third period injection speed chooses the middle value, the packing pressure chooses the middle value and the packing time chooses the biggest value. In this research, the author gets the values of extension engineering then uses the superposition from the interaction and parameters effect to get the optimal process. The classical region and extension region are shown on Table 2. The details of extension engineering are shown on [3]. Key Engineering Materials Vols. 364-366 (2008) pp 43-47 online at http://www.scientific.net © (2008) Trans Tech Publications, Switzerland Online available since 2007/Dec/06 All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of the publisher: Trans Tech Publications Ltd, Switzerland, www.ttp.net. (ID: 130.203.133.34-14/04/08,11:46:01) The optimal problem: 1 2 2 1 1 1 x w x w ) x ( f min − − × + × = Constraints: max min max min max , injection injection min , injection max , mold mold min , mold max , injection injection min , injection t t t ; P P P T T T T T T