Study On The Conditions Of Liquid Crystal Alignment Technique For LCD

Liquid crystal plays an important role in the field of display and communications, especially for the display, Liquid Crystal Device is the most common flat panel device in the world. Liquid crystal alignment technique is to make LC molecules align orderly on the substrate. Aligned LC layer has some properties of crystal such as birefringence, optical rotation, chromatic dispersion and so on. LC devices modulate lights because of birefringence, so alignment technique is a fundamental aspect for its application. Meanwhile, LC alignment directly relates to the response time, viewing angle and the threshold voltage of the LCD. Thus how to control and measure the alignment precisely has become an important issue for the research on LC physics and applications. This thesis mainly consists of four aspects:1. By the analysis of the two types of alignment techniques, their advantages and disadvantages are discussed and the impact of alignment techniques on pretilt angle is pointed out.2. Through the theoretical analysis of crystal rotation method and the experimental testing of the equipments, the measuring platform is designed and implemented to measure the pretilt angle of the liquid crystal molecules.3. During the experiment, the LCD panel is successfully prepared after the thorough study of its conditions and parameters in each manufacturing process, especially the study of the parameters in the liquid crystal alignment process.4. According to the parameters involved in the rubbing method, the experiment is made to determine the fact that the pretilt angle of the liquid crystal molecules is influenced by both the strength and the frequency of rubbing. Meanwhile, studies on the measuring of the multi-point pretilt angle in the LCD panel indirectly reflect its uniformity of alignment.In short, this thesis studies the liquid crystal alignment technique and provides a fundamental measurement platform for further experiment, gains the parameters of the production of the LCD panel and gets the desired pretilt angle by means of controlling the quantitative parameters of rubbing.