Shift register

Abstract

In a shift register for driving a pixel row in a liquid crystal display device a plurality of stages are connected: to a high level voltage source, a low level voltage source and a phase-delayed clock signal generator; to row lines; and in cascade, with respect to a scanning signal, for charging and discharging the row lines. Each stage of the shift register has a pull-up transistor, a pull-down transistor, and first to fourth transistors. The pull-up transistor has a control electrode and a conduction path connected between the first clock signal line and the output terminal. The pull-down transistor has a control electrode and a conduction path connected between the low level voltage line and the output terminal. The first and second transistors have conduction paths connected in series between the input terminal and the control electrode of the pull-up transistor, and each has a control electrode connected commonly to the second clock signal line. The first and second transistors allow a voltage to be charged on the control electrode of the pull-up transistor. The third and fourth transistors have conduction paths connected in series between the third clock signal line and the control electrode of the pull-down transistor, and each has a control electrode connected commonly to the third clock signal line. The third and fourth transistors allow a voltage to be charged on the control electrode of the pull-down transistor.