By virtue of such advantageous features as light weight, small thickness and low power consumption, liquid crystal display devices have been used in various fields as display devices of OA equipment, such as personal computers, and TVs. In recent years, liquid crystal display devices have also been used as display devices of portable terminal equipment such as mobile phones, car navigation apparatuses, game machines, etc.
In recent years, a liquid crystal display panel of a fringe field switching (FFS) mode or an in-plane switching (IPS) mode has been put to practical use. The liquid crystal display panel of the FFS mode or IPS mode is configured such that a liquid crystal layer is held between an array substrate, which includes a pixel electrode and a common electrode, and a counter-substrate, and switching is realized by rotating liquid crystal molecules of the liquid crystal layer in a plane parallel to the substrates. Such a display mode has an advantage of, for example, a wide viewing angle.
In the structure of the FFS mode or IPS mode, there has been a demand for an improvement of various display defects due to a displacement of an alignment direction of liquid crystal molecules from a desired direction. For example, in some cases, an image persistence phenomenon occurs on the liquid crystal display device of the FFS mode. The image persistence phenomenon is such a phenomenon that, for example, if an intermediate gradation image is displayed on the entire screen after a black-and-white checkered pattern is displayed on the screen, the checkered pattern slightly remains like an after-image. In recent years, various methods have been proposed for relaxing such an image persistence phenomenon.