The Liquid Crystal Display (LCD) possesses advantages of thin body, power saving and no radiation to be widely used in many application scope. Such as LCD TV, mobile phone, personal digital assistant (PDA), digital camera, notebook, laptop, and dominates the flat panel display field.
Most of the liquid crystal displays on the present market are backlight type liquid crystal displays, which comprise a liquid crystal display panel and a backlight module. The working principle of the liquid crystal display panel is that the Liquid Crystal is injected between the Thin Film Transistor Array Substrate (TFT array substrate) and the Color Filter (CF). The light of backlight module is refracted to generate images by applying driving voltages to the two substrates for controlling the rotations of the liquid crystal molecules.
The Active Matrix Liquid Crystal Display (AMLCD) is the most common liquid crystal display device at present. The Active Matrix Liquid Crystal Display comprises a plurality of pixels, and each pixel comprises a Thin Film Transistor (TFT). The gate of the TFT is coupled to the scan line extending along the horizontal direction. The drain of the TFT is coupled to the data line extending along the vertical direction. The source of the TFT is coupled to the corresponding pixel electrode. When a sufficient positive voltage is applied to some scan line in the horizontal direction, all the TFT coupled to the scan line will be activated to write the data signal loaded in the data line into the pixel electrodes and thus to show images to control the transmittances of different liquid crystals to achieve the effect of controlling colors.
The driving of the level scan line (i.e. the gate driving) in the present active liquid crystal display is mainly accomplished by the external Integrated Circuit (IC). The external IC can control the charge and discharge stage by stage of the level scan lines of respective stages. The GOA technology, i.e. the Gate Driver on Array technology can utilize the original manufacture processes of the liquid crystal display panel to manufacture the driving circuit of the level scan lines on the substrate around the active area, to replace the external IC for accomplishing the driving of the level scan lines. The GOA technology can reduce the bonding procedure of the external IC and has potential to raise the productivity and lower the production cost. Meanwhile, it can make the liquid crystal display panel more suitable to the narrow frame or non frame design of display products.
The scan way of the gate driving circuit according to prior art is generally simple, and only can perform forward scan or backward scan at a time, and perform scan row by row or interlaced scan at a time. Therefore, it is necessary to improve the gate driving circuit according to prior art for realizing the variety of scans for satisfying demands of various display products.