Bidirectional shift register

1. A bidirectional shift register comprising:

multi-stages of shift register unit circuits that transmit a start pulse in a direction indicated by a logical level of a transmission direction control signal,

wherein each of the shift register unit circuits has:

a first transfer gate that transmits the start pulse in synchronization with one of a clock signal and an inverted clock signal, the inverted clock signal being obtained by inverting the clock signal;

a second transfer gate that transmits the start pulse in synchronization with the other signal of the clock signal and the inverted clock signal;

a first logical circuit that inverts an input signal and outputs the inverted signal; and

first and second clocked inverters that are exclusively valid according to the logical level of the transmission direction control signal,

an output terminal of the first logical circuit is connected to input terminals of the first and second clocked inverters, and

output terminals of the first and second clocked inverters are connected to an input terminal of the first logical circuit through the first and second transfer gates.

2. The bidirectional shift register according to claim 1 , further comprising:

a reset circuit that outputs a reset signal,

wherein the first logical circuit is a NOR circuit that inverts a signal output from the first or second transfer gate and the reset signal and calculates a logical sum of the inverted signals.

3. The bidirectional shift register according to claim 1 , further comprising:

a reset circuit that outputs a reset signal,

wherein the first logical circuit is a NAND circuit that inverts a signal output from the first or second transfer gate and the reset signal and calculates a logical product of the inverted signals.