Intermediate pre-tilt angle control by a composite alignment thin film structure for liquid crystal displays.
We designed a patterned composite alignment thin film structure using a horizontal alignment polyimide (PI) layer and vertical alignment liquid crystal polymer (LCP) pillars. The LCP polymer precursor concentration was varied at 0-10% and the pillars were introduced by a photolithography process. Both single-sided and double-sided liquid crystal display cells were assembled for a series of electro-optical characterization techniques. The horizontal PI alignment layer alone had a designated control of the pre-tilt angle of 7 degrees after the prescribed mechanical rubbing process. The pre-tilt angle was improved to 24 degrees when the LCP precursor concentration was 5%. It was further increased to 61 degrees at the concentration of 10%. In addition, the study on the electrical response time and gray level variation demonstrated promising results for potential applications. The field-on response time was only 2.79 ms and the field-off response time was 0.35 ms for the double-sided liquid crystal display cells using a ramping voltage of 5.5 V. The effective control of the cell pre-tilt angle suggested that the display power consumption and response time would be greatly improved.
Wu
G M
GM
Institute of Electro-Optical Engineering, Department of Electronic Engineering, Chang Gung University, Kweisan, Taoyuan, Taiwan, Republic of China. wu@mail.cgu.edu.tw
Chien
H W
HW
Huang
J W
JW
Zeng
H L
HL