Applying TRIZ Method and PID Control for Problem Solving in the TFT-LCD Manufacturing Process

Abstract

The advent of monitors changed people’s lifestyles tremendously. The TFT-LCD has become the most widely used flat-panel display technology. A TFT-LCD consists of two polarization filters with a 90°difference in orientation and liquid crystal placed between them. The liquid crystal changes the light’s direction and leads the light through both polarization filters. When voltage is applied to the liquid crystal, the light remains in a constant direction and is therefore blocked by the two filters. Continuous process improvement is essential and manufacturers employ traditional trial and error to search for quick solutions. However, the lack of comprehensive problem definition may cause the same or similar problems to occur repeatedly. This study aimed to identify and resolve issues in the TFT-LCD manufacturing process through a systematic approach. Function analysis is used to identify functional disadvantages: (1) liquid crystal overflows onto the PI and (2) the liquid crystal contains air. Cause–Effect Chains and Contradiction Analysis was then performed to identify engineering contradictions and corresponding parameters, such as (1) “Volume of moving object” and “Manufacturing precision” and (2) “Volume of moving object” and “Extent of automation”. After applying the Contradiction matrix, inventive principle, “Partial or excessive action”, is suggested. We propose applying the concept of PID control to vary the system output around the desired value and ultimately reach the desired value. Thus, the dispensing pressure accuracy can be enhanced, and the problems of liquid crystal overflow and air bubbles can be eliminated.