Bi-directional shift register

A bi-directional shift register including a plurality of shift register units coupled in series, wherein:

• an (n−1)th stage shift register unit among the plurality of shift register units is configured to provide an (n−1)th stage output voltage according to a first clock signal and an (n−1)th stage input voltage;
• an nth stage shift register unit among the plurality of shift register units is configured to provide an nth stage output voltage according to a second clock signal and an nth stage input voltage;
• an (n+1)th stage shift register unit among the plurality of shift register units is configured to provide an (n+1)th stage output voltage according to a third clock signal and an (n+1)th stage input voltage;
• and
• the nth stage shift register unit includes:
• an output end for outputting the nth stage output voltage;
• an nth node;
• a pull-up circuit configured to provide the nth stage output voltage according to the second clock signal and a voltage level of the nth node;
• an input circuit configured to receive the (n−1)th stage output voltage and the (n+1)th stage output voltage, supply the (n−1)th stage output voltage as the nth stage input voltage when the bi-directional shift register scans in a first direction, supply the (n+1)th stage output voltage as the nth input voltage when the bi-directional shift register scans in a second direction opposite to the first direction, and conduct the pull-up circuit according to the (n−1)th stage output voltage and the (n+1)th stage output voltage, the input circuit comprising:
• a first switch including:
• a first end coupled to a first bias voltage higher than a voltage for conducting the pull-up circuit;
• a second end coupled to the nth node;
• and
• a control end for receiving the (n−1)th stage output voltage;
• and
• a second switch including:
• a first end coupled to a second bias voltage higher than the voltage for conducting the pull-up circuit;
• a second end coupled to the nth node;
• and
• a control end for receiving the(n+1)th stage output voltage;
• and
• a pull-down circuit configured to turn off the pull-up circuit according to a first voltage received from an xth stage shift register unit among the plurality of shift register units when the bi-directional shift register scans in the first direction, and configured to turn off the pull-up circuit according to a second voltage received from a yth stage shift register unit among the plurality of shift register units when the bi-directional shift register scans in the second direction, wherein n is a positive integer larger than 1, x is an integer larger than n, and y is a positive integer smaller than n.