1. Field of Invention
The present invention relates to a driving circuit of a liquid crystal display device, and more particularly to a low color scale driving circuit of a liquid crystal display device.
2. Related Art
A liquid crystal display device usually includes a pair of parallel glass substrates between which is provided the assembly at least of an indium tin oxide (ITO) film, an alignment film and a color filter. The slot directions of the alignment films are perpendicular to each other. A liquid crystal material is placed between the substrates along the slots of the alignment film. When an electric field is applied between the substrates, the liquid crystal molecules become vertical to the slots so that light cannot pass and consequently black color is shown on the display screen. Therefore, a display can be implemented through controlling the liquid crystal molecules according to the variation of the electric field.
FIG. 1 shows a driving circuit of a conventional liquid crystal display device. A driving circuit 100 includes a timing controller 110 and a source driver 120. The source driver 120 receives a digital image signal 302 from the timing controller 110 and accordingly generates an analog signal 303 for controlling a liquid crystal display panel 200. The timing controller 110 converts the image data into a digital image signal 302 and outputs the digital image signal 302 to the source driver 120. The timing controller 110 further outputs a control signal that is a polarity-inverting signal 301 for controlling the polarity of an analog voltage from the source driver 120.
A color display scheme with 8, 64 or 128 color scales usually uses a driving circuit having the above architectures. For a 256-color-scale display device, 8, 64, 128 and 256 color scales must be all included, which consumes higher electric power.
The number of color scales is one important factor that influences the display quality. The greater number of color scales, the higher power is needed. Although power consumption is not the most serious concern for a liquid crystal display device of a desktop computer, it may be critical for a small display device of a portable electronic device such as a cell phone, a personal digital assistant or a laptop computer.
Therefore, there is a need of a display device with lower power consumption, suitable for use in a portable electronic device.