Automatic adjusting device and automatic adjusting method for common voltage

The invention provides an automatic adjusting device for common voltage. The automatic adjusting device comprises a photoelectric sensor, a waveform processing device and a data processor, the photoelectric sensor acquires display picture information of the display panel and performs photoelectric conversion to obtain a first alternating-current electric signal; the waveform processing device is connected with the photoelectric sensor to perform waveform processing on the first alternating current signal to obtain a second alternating current signal; the data processor is connected with the waveform processing device so as to control the power supply chip to adjust the common voltage, determine the flicker degree corresponding to the display frame according to the second alternating current signal and determine the optimal common voltage value when the flicker degree of the display frame is minimum. The invention further provides an automatic adjusting method of the common voltage. According to the invention,