The In Cell touch screen is completed by adding the touch screen function inside the liquid crystal, which is added to the liquid crystal manufacturing process. Although it has the function of a touch screen, this is not to the extent that touch screen manufacturers can make a long story. The general TP (Out Cell) is placed on the LCD panel, so the overall thickness becomes thicker, thereby increasing the overall weight. In addition, it is more important to affect the optical properties of the display.
In Cell touch screen can solve the problems such as dullness caused by reduced contrast and high-resolution dizziness. In Cell touch screens are also divided into three categories: "resistive", "capacitive" and "optical" according to different detection technologies.
Resistive In Cell is to form a conductive spacer on each pixel that is lower than the spacer in the liquid crystal panel box. Through this conductive spacer and the spacer on the TFT substrate, the switch function is realized, and the occurrence of pressure is realized. Touch to input. The sensor is formed in the B pixel to minimize the impact on the display performance (see Figure 3-9). However, in this method, the density of the spacer has some influence on the display performance, and the touch input must require a certain amount of pressure. In addition, there are issues such as the strength of the spacer and the shedding of ITO that need to be resolved.
Although many solutions have been proposed to implement capacitive In Cell touch screens, they have not yet been put into practical use. The detailed structure will not be elaborated here, but the following three are well known.
Capacitive 1
Same as the resistive type, a spacer is set to detect the change of the box thickness and capacitance during touch. This is also the same as the resistive touch screen, which requires a certain amount of pressure during touch.
-Capacitive 2
A method to detect the change in the capacitance of liquid crystal molecules caused by pressure. The use of LTPS TFT technology has achieved high definition, but it will also change the orientation of the liquid crystal molecules, causing abnormal display.
-Capacitive 3
is a way to build TP in a liquid crystal display using Field Sequential technology. There is no big problem, but there is a little color break phenomenon.
Using an optical process to form a photodiode in each pixel, the reflection or shadow of light is used to identify the finger or pen to detect the touch position. Although it has a scanning function, it is difficult to input if the surrounding infrared light is relatively strong. Although major companies are also publishing various methods, the one used in the touchpad part of notebook computers is the only marketed product. It has a mouse function that can realize multi-touch, and it also adds interesting applications that match the panel.
