(a) Field of the Invention
The present invention relates to a panel for a display device and a liquid crystal display including the panel.
(b) Description of the Related Art
Liquid crystal displays (LCDs) are one of the most widely used flat panel displays. An LCD includes two panels having field-generating electrodes and a gap interposed therebetween, a liquid crystal (LC) layer filled in the gap between the panels, and a plurality of spacers sustaining the gap.
The LCD displays images by applying voltages to the field-generating electrodes to generate an electric field in the LC layer, which determines orientations of LC molecules in the LC layer to adjust polarization of incident light.
Among LCDs including field-generating electrodes on respective panels, one kind of LCD provides a plurality of pixel electrodes arranged in a matrix at one panel and a common electrode covering an entire surface of the other panel. The image display of the LCD is accomplished by applying individual voltages to the respective pixel electrodes. For the application of the individual voltages, a plurality of three-terminal thin film transistors (TFTs) are connected to the respective pixel electrodes, and a plurality of gate lines for transmitting signals for controlling the TFTs and a plurality of data lines for transmitting voltages to be applied to the pixel electrodes are provided on the panel.
An LCD also includes a thick light blocking film for blocking light incident on the TFTs since the TFTs generally include amorphous silicon that generates light-induced leakage current. However, the light blocking film may cause light leakage near its edges.
In particular, the light leakage near the edges of the light blocking film is severe in a vertically aligned (VA) mode LCD having excellent contrast ratio. Since a VA LCD generally includes a liquid crystal layer having negative dielectric anisotropy, alignment vertical to the panels, and crossed polarizers, it may almost completely block light in the absence of an electric field and thus it realizes an excellent black state. However, edges of the thick light blocking film pretilts liquid crystal molecules to cause the light leakage in the black state, thereby increasing the luminance in the black state to drastically decrease the contrast ratio.