Intermediate pre-tilt angle control by a composite alignment thin film structure for liquidcrystal displays

Abstract

We designed a patterned composite alignment thin film structure using a horizontalalignment polyimide (PI) layer and vertical alignment liquid crystal polymer (LCP) pillars.The LCP polymer precursor concentration was varied at 0–10% and the pillars wereintroduced by a photolithography process. Both single-sided and double-sided liquid crystaldisplay cells were assembled for a series of electro-optical characterization techniques. Thehorizontal PI alignment layer alone had a designated control of the pre-tilt angle of7° after the prescribed mechanical rubbing process. The pre-tilt angle was improved to24° when the LCP precursor concentration was 5%. It was further increased to61° at the concentration of 10%. In addition, the study on the electrical response time and graylevel variation demonstrated promising results for potential applications. The field-onresponse time was only 2.79 ms and the field-off response time was 0.35 ms for thedouble-sided liquid crystal display cells using a ramping voltage of 5.5 V. The effectivecontrol of the cell pre-tilt angle suggested that the display power consumption and responsetime would be greatly improved.