Suppressing pretilt angle for enhancing black quality in diagonal viewing angle of homogenously aligned liquid crystal display

ABSTRACT

The diagonal viewing angle light leakage in a black state of in-plane switching (IPS) liquid crystal display (LCD) associated with pretilt angle has been investigated. The mechanical rubbing process with a cloth causes relatively high pretilt angle in the homogenously aligned liquid crystals (LCs) so that the tilted LC director results in increase of a light leakage in a black state at diagonal viewing angles. In this study, we theoretically estimated using classical optic theory how the light leakage in a black state at diagonal viewing angle is associated with the pretilt angle and also proposed an effective method to reduce the pretilt angle from 1.5° to 0° in rubbed IPS LCD by utilising polymer stabilisation. With this approach, we could successfully acquire a better black quality in all viewing angles as compared with normal IPS LCD.

GRAPHICAL ABSTRACT

KEYWORDS:

• In-plane field switching
• dark state
• pretilt angle
• polymer stabilisation

Acknowledgement

We deeply appreciate Merck Advanced Technology of Korea and JSR Corporation for their kind support of the research.

Disclosure statement

No potential conflict of interest was reported by the authors.