The touch screen is widely used in portable electronics mainly based on mobile phones, and gradually develops to other display terminal devices and other applications. Compared with the method of setting the touch panel on the liquid crystal panel, it is more popular to integrate the touch panel function with the liquid crystal panel. The integration of the touch panel and the liquid crystal panel includes the "In-cell" method and the "On-cell" method. In-cell refers to the method of embedding the touch panel function in the liquid crystal pixels. On-cell refers to the method of embedding the touch panel function between the color filter substrate and the polarizing plate.
If the original external touch panel components can be integrated with the liquid crystal panel, the panel can be made thinner and lighter. In addition, when the touch panel is placed outside the liquid crystal, there will be a gap between the liquid crystal and the touch panel, so that light reflection will occur between the liquid crystal panel and the touch panel, resulting in reduced visibility under strong outdoor light. If the external touch panel components can be integrated, there will be no reduction in outdoor visibility.
In-cell technology has failed to make progress due to difficulties in ensuring yield and display performance. The In-cell method needs to embed the touch sensor function inside the pixels on the TFT array substrate. This complicates the semiconductor manufacturing process and reduces the yield. In addition, if the touch sensor is embedded in the pixel, the displayable area will be reduced, which will result in deterioration of the image quality.
With the emergence of On-cell technology, the integration of liquid crystal panels and touch panels has become simple. It is only necessary to form a simple transparent electrode pattern between the filter substrate and the polarizing plate to realize touch control, which also easily improves the yield. In addition, the area of the effective display area within the pixel does not change, and the image quality does not deteriorate.
The difference between In-cell and On-cell
At present, the touch screens used in the market are mainly separate touch screens, that is, the touch panel and the liquid crystal panel are produced separately and then assembled together. In order to reduce the thickness and cost of the panel, an integrated touch solution was created. A touch sensor is embedded inside the LCD panel, that is, a built-in touch screen. However, due to the impact on the display performance, and the yield is difficult to guarantee, the cost of mass production is higher. On-cell technology can completely solve this problem. The former method is called "In-cell", and the latter method of configuring touch sensors on the LCD panel is called "On-cell".
LCD panel manufacturers only need to add an integrated process to the process to realize the integration of touch panels, and then hand over to the equipment manufacturers. This move will benefit LCD panel manufacturers involved in the field of touch panels, while independent touch panel manufacturers will lose more opportunities.