(a) Field of Invention
The present disclosure of invention relates to liquid crystal displays (LCDs) and more specifically to wide screen LCDs in which long gate lines may appear as slow RC delay lines.
(b) Description of the Related Art
Liquid crystal displays (LCDs) are one of the most widely used flat panel displays. They may be found in a variety of applications, including high resolution computer monitors and wide-screen high definition television displays. An LCD typically includes two spaced-apart panels provided with opposed field-generating electrodes between which electric fields are generated for changing orientation of liquid crystal material interposed between the panels. The opposed electrodes are often referred to as pixel electrodes on one panel and a common electrode on the other panel, where the liquid crystal material layer is interposed therebetween. An LCD typically displays images by applying different voltages to the pixel-electrodes so as to thereby generate different electric fields passing through the liquid crystal layer, and thereby determining the orientations of the liquid crystal molecules in the liquid crystal layer and adjusting polarization of passing-through light.
An LCD also typically includes on one of its panels, a plurality of switching elements connected to respective ones of the pixel electrodes, and a plurality of signal lines such as gate lines and data lines operatively coupled to the switching elements (e.g., TFTs or thin film transistors) for respectively gating the switching elements and for passing through data voltages that are to be used to charge the corresponding pixel electrodes.
The gate lines and data lines are structure driven by gate driving circuits and the data driving circuits where the latter may be implemented as a plurality of monolithic integrated circuit (IC) chips directly mounted on the panel that contains the switching elements (e.g., TFTs) or mounted on a flexible printed circuit film which attaches to the panel. It is common for these gate and data signal driving IC chips to take up a large part of the manufacturing cost of an LCD. Particularly, since the cost of an analog data driving IC chip is very high compared to the cost of a digital gate driving circuit chip, it would be advantageous if the number of and/or required switching speeds of analog data driving IC chips can be decreased, especially in the case of a large-sized LCDs (e.g., wide screen LCDs) having high resolution. The cost of the digital gate driving circuit can be reduced by integrating the circuitry of that gate driving circuit into the TFT panel substrate together with the gate lines, the data lines, and the panel's switching elements (TFT's). However, as for the analog data driving circuits, because they typically have a different IC fabrication technology, it is hard to integrate the analog data driving circuits into the TFT panel substrate due to the more complex structure of the analog circuitry and thus it is all the more desirable to reduce the number of and/or required switching speeds of IC chips used to implement the analog data driving circuits due to cost considerations.
In the case of wide-area, high definition LCDs there is another concomitant problem. The gate and data lines which couple to distributed switching elements across the wide-area LCD are relatively narrow and thus appear to function as RC delay lines that deliver signals of smaller size and greater delay to switching elements further downstream on the line away from the signal driving circuit. Due to the uneven distribution of signal strength and signal arrival time across the display area, the image quality of the LCD may be deteriorated. This problem gets worse as the signal switching bandwidth required along all points on each RC-type delay line grows.
The above information disclosed in this Background section is only for enhancement of understanding of the motivations that drive the present disclosure of invention and therefore the above information (alone or in combination) may contain information that does not form part of the prior art as known to persons of ordinary skill in the art prior to public release of this disclosure.