Since the capacitive screen is controlled by capacitive induction, it indicates that the stability of the capacitive screen on the power supply is very high. The alternating current waveform is a sine curve, and the battery power supply is direct current, and the stability is high. Direct charge, with the general inferior charger will make the screen work improperly, that is because the stability of the inferior charger is poor, the capacitor used is too poor or no inductor, there is a very serious ripple when detected with the oscilloscope, and some chargers because the capacitor aging for a long time leads to the pulse waveform of the pulse transformer can not be removed clean, resulting in residual waveform.