Patent ID: 7098882

Claim:
A bidirectional shift register comprising: an output circuit that includes a first transistor having a conductive path between a first clock terminal and an output terminal and a second transistor having a conductive path between a power supply electrode and the output terminal; an input circuit that includes a third transistor having a conductive path between a forward direction pulse input terminal and a control electrode of the first transistor, a fourth transistor having a conductive path between a backward direction pulse input terminal and the control electrode of the first transistor and a fifth transistor having a conductive path between the power supply electrode and a control electrode of the second transistor; a reset circuit that includes a sixth transistor having a conductive path between a second clock terminal and the control electrode of the second transistor, a seventh transistor having a conductive path between a third clock terminal and the control electrode of the second transistor and an eighth transistor having a conductive path between the power supply electrode and the control electrode of the first transistor, which makes the path between the sixth transistor, the control electrode of the second transistor and a control electrode of the eighth transistor conductive as well as making the path between the fifth transistor and the seventh transistor non-conductive in forward direction pulse shift and which makes the path between seventh transistor, the control electrode of the second transistor and the control electrode of the eighth transistor conductive as well as making the path between the fifth transistor and the sixth transistor non-conductive in backward direction pulse shift; and an inversion preventing circuit that prevents inversion of a voltage level in the control electrode of the second transistor when a voltage level of a clock signal inputted to the first clock terminal is inverted in a state where the first transistor is on and the second transistor is off.