Embodiments of the present invention relate to a liquid crystal display (LCD) panel and a method of manufacturing the same.
A LCD panel comprises a first substrate and a second substrate, which are usually an array substrate and a color filter substrate respectively. The LCD panel is formed through injecting liquid crystal into the space between the two substrates. During manufacturing of a LCD panel, the thickness of the liquid crystal layer is an important parameter, controlled by the distance between the two substrates, i.e., the cell gap.
To maintain a consistent cell gap between the two substrates across the entire LCD panel, the first substrate and the second substrate, before assembled together, have spacers with a certain height disposed in between. Typical spacers have two major types, ball spacers (BSs) and post spacers (PSs). BSs are usually dispensed onto the first or the second substrate through sputtering; the positioning of BSs is, therefore, inaccurate, which may lead to light leakage. If employed, PSs are usually provided on the black matrix of the color filter substrate or in the light-shielding areas of the array substrate, such as the TFT (Thin Film Transistor) switches, the gate lines, or the data lines. In contrast with BSs, PSs can be positioned in the non-display area or the light-shielding area with high accuracy, which avoids light leakage.
Notwithstanding the above, a LCD panel employing PSs to maintain the cell gap has some shortcomings. For a LCD panel that is manufactured at room temperature, its liquid crystal's volume increases at high temperature due to thermal expansion; while a LCD panel is positioned vertical to the ground when in use, it, therefore, may have the defect of gravity mura. A LCD panel's volume decreases at low temperature due to contraction, which produces voids in the liquid crystal and causes the defect of bubbling. PSs are usually made of a material such as Polymethyl Methacrylate (PMMA) or Polycarbonate (PC), whose Coefficient of Thermal Expansion (CTE) does not well match that of liquid crystal; as a result, it is hard to avoid gravity mura and bubbling, which tremendously lowers the display quality of a LCD display.
USPTO Backgrounds
USPTO Backgrounds