Patent ID: 7983379

Claim:
A shift register for providing a plurality of low level shift register signals, the shift register comprising a plurality of shift register units connecting in series, each shift register unit comprising a first inversion circuit, a second inversion circuit, and a third inversion circuit; the third inversion circuit receiving a first clock signal from an external circuit, and comprising a first transistor for outputting the first clock signal, and a second transistor for outputting an turning off signal; the first inversion circuit comprising a third transistor in an on state for discharging at an output end for keeping a stable output signal, a fourth transistor and a fifth transistor, a drain of the fifth transistor receiving a low level voltage from the external circuit, a gate of the fifth transistor and a source of the fourth transistor receiving the output signal from a pre-stage shift register unit, a source of the fifth transistor connected to a drain of the fourth transistor, a gate of the fourth transistor receiving a second clock signal having a phase inversed to a phase of the first clock signal, a gate of the third transistor receiving the low level voltage, a drain of the third transistor connected to the source of the fifth transistor, and the first inversion circuit outputting an output signal to the third inversion circuit and the second inversion circuit via a source of the third transistor; the second inversion circuit receiving the output signal from the first inversion circuit, and outputting a control signal to control the turn-on and turn-off of the second transistor; wherein when the output signal of the first inversion circuit is a turn on signal to switch on the first transistor, the first clock signal is output through the first transistor and the second transistor is switched off under the control of the second inversion circuit, when the output signal of the first inversion circuit is a turn off signal to switch off the first transistor, the second transistor is switched on under the control of the second inversion circuit.