1. Field of the Invention
The present invention relates to a thin film transistor (“TFT”) display plate and a liquid crystal display (“LCD”) having the same, and more particularly, to an LCD capable of reducing a load on a gate line, increasing an aperture ratio and preventing light leakage.
2. Description of the Related Art
A liquid crystal display (“LCD”) includes a common electrode display plate including a color filter and a thin film transistor (“TFT”) display plate including a TFT array. The common electrode display plate and the TFT display plate are opposite to and face each other when assembled with a seal line interposed between the two plates. A liquid crystal layer is formed at an air gap defined between the common electrode display plate and the TFT display plate. In particular, an LCD includes a common electrode display plate and a TFT display plate including respective electrodes and a liquid crystal layer interposed between the two display plates. When a voltage is applied to the electrodes, the LCD displays an image by adjusting the amount of light transmitted therethrough by rearrangement of liquid crystal molecules of the liquid crystal layer. Since an LCD is a non-emissive device, a backlight unit used as a light source is located at the back of the TFT display plate. The transmittance of light emitted from the backlight is adjusted by controlling the orientation of liquid crystals of the liquid crystal layer.
The thin film transistor (“TFT”) display plate includes a plurality of gate lines, data lines and pixel electrodes. The gate lines extend in a row direction and transmit a gate signal. The data lines extend in a column direction and transmit a data signal. Each pixel of the TFT display plate is connected to a gate line and a data line and includes a switching device and a storage capacitor.
Here, the switching device is formed at an intersection point between a gate line and a data line and is a three-terminal device including a control terminal connected to a gate line, an input terminal connected to a data line and an output terminal connected to a pixel electrode. The storage capacitor and a liquid crystal capacitor are connected to the output terminal of the switching device.
A conventional LCD includes a storage capacitor to store a data voltage applied to a pixel electrode. One terminal of the storage capacitor is connected to the output terminal of the switching device and the other terminal of the storage capacitor is connected to a previous gate line. Such a connection scheme is referred to as a previous gate scheme.
With the tendency of LCDs becoming larger in size and having more pixels, a storage capacitor configured according to the previous gate scheme imposes a large load on a gate line, causing signal delay. As a result, it is difficult to effectively implement the storage capacitor. In particular, when a drive integrated circuit (“IC”) is directly formed on a TFT array plate according to an amorphous silicon gate (“ASG”) scheme, the circuit (or wire) of the drive IC should be formed in a large area to reduce a load increased by the storage capacitor configured according to the previous gate scheme.
Moreover, in the conventional LCD, a black matrix is formed on a common electrode display plate corresponding to a data line to prevent light leakage around the data line. Since light generated from backlight under a TFT display plate is incident at various angles with respect to the data line and is reflected at a large angle from the data line, a black matrix having a large area needs to be formed to prevent light leakage. Since the increase in the area of the black matrix leads to a decrease in the aperture ratio of an LCD, luminance is degraded while light leakage is prevented.
USPTO Backgrounds
USPTO Backgrounds