With the development of display technology, the flat panel device, such as Liquid Crystal Display (LCD) possesses advantages of high image quality, power saving, thin body and wide application scope. Thus, it has been widely applied in various consumer electrical products, such as mobile phone, television, personal digital assistant, digital camera, notebook, laptop, and becomes the major display device.
Most of the liquid crystal displays on the present market are back light type liquid crystal displays, which comprise a liquid crystal display panel and a back light module. The working principle of the liquid crystal display panel is to locate liquid crystal molecules between two parallel glass substrates, and a plurality of vertical and horizontal tiny electrical wires are between the two glass substrates. The light of back light module is reflected to generate images by applying driving voltages to control whether the liquid crystal molecules to be changed directions.
Generally, the liquid crystal display panel comprises a CF (Color Filter) substrate, a TFT (Thin Film Transistor) substrate, LC (Liquid Crystal) sandwiched between the CF substrate and the TFT substrate and sealant. The formation process generally comprises: a forepart Array process (thin film, photo, etching and stripping), a middle Cell process (Lamination of the TFT substrate and the CF substrate) and a post module assembly process (Attachment of the driving IC and the printed circuit board). The forepart Array process is mainly to form the TFT substrate for controlling the movement of the liquid crystal molecules; the middle Cell process is mainly to add liquid crystal between the TFT substrate and the CF substrate; the post module assembly process is mainly the driving IC attachment and the integration of the printed circuit board. Thus, the liquid crystal molecules are driven to rotate and display pictures.
The Active Matrix (AM) liquid crystal display is the most common liquid crystal display at present. The AMLCD manufacture technology utilizes the skill of manufacturing Color Filter on Array (COA) on the TFT array substrate, which can raise the aperture ratio of the liquid crystal panel and reduce the parasitic capacitance. Because the COA skill is utilized in the manufacture process, one side of the TFT array substrate is flatter, and the photospacer (PS) can be manufactured on one side of the TFT array substrate. The location of the photospacer is fixed at the one side of the TFT array substrate for reducing the probability of MM mura (phenomena of picture misalignment and uneven brightness) occurrence, and meanwhile, lowering the alignment demands for the upper, lower substrates in the lamination process.
However, the photospacer is formed at the one side of the TFT array substrate, one photo process is added at the one side of the TFT array substrate, which can extend the Array process time and diminish the production efficiency.
Please refer to FIG. 1, which is a COA type liquid crystal panel. In the manufacture process of the one side of the TFT array substrate, the TFT layer 200, the color resist layer 300, the protective layer 400, the pixel electrode layer 500 and the photospacer layer 600 are sequentially formed on the lower substrate. One photo process of the photospacer layer 600 is added, thus, the Array process time is longer and the production efficiency is diminished.