For capacitive touch screen systems, performance indicators can be divided into: operating temperature range, power consumption, signal-to-noise ratio, scanning speed, waterproof, ESD, anti-RF interference capability and packaging.
The signal-to-noise ratio is the core indicator. Most of the performance in the user experience depends on the signal-to-noise ratio. For example, the accuracy of the touch coordinates, the jitter size of the touch coordinates, and the linearity of the scribing are all dependent on the signal-to-noise ratio. According to the relationship between the touch screen and the display screen, the touch coordinate accuracy should meet the requirements of each pixel on the display screen. With this, it can be calculated that the signal-to-noise ratio of the capacitive touch screen system is about 50 (34dB). According to the system in different environments, the signal-to-noise ratio may decrease
There is no quantitative index for the ability to resist RF interference. Only from a qualitative requirement, in a normal use environment, including GSM signals, CDMA signals, WIFI signals, microwave oven signals and this kind of civilian wireless communication equipment must not interfere with the normal operation of the touch screen.
The scanning speed is defined as the speed at which the touch screen controller scans the touch screen. According to the characteristics of touch keys, a keystroke will exceed 20mS. As long as you scan once within 20mS, you will be able to scan the touch.
In the process of touching, the fingers will sweat. When a device with a capacitive touch screen enters a hot place from a colder place, a layer of water mist will appear on the surface of the capacitive touch screen. It is required that the capacitive touch screen can be used normally in both cases.
For devices using capacitive touch screens, the working environment is very different, and the suitable temperature range must be wide, otherwise it may cause the user to remain unchanged. Generally, the operating temperature range of capacitive touch screen is -20°C-70°C.
