For detecting line short defects in a display panel, a driving circuit has a plurality of shift registers, a plurality of diode modules, and at least one power supply. Each shift register has an output port for outputting a driving signal sequentially. The diode modules are coupled to the output ports of the shift registers accordingly. The power supply is coupled to the diode modules and forward biases the diode modules to bypass the shift registers during at least a part of a period of detecting line short defects.