Shift register and display device provided with same
Each unit circuit that constitutes each of stages of a shift register is provided with a charge supply unit including a third node whose potential becomes high level at identical timing with a first node (a node for holding an electric charge in order to output a scanning signal (output signal) at high level), and capable of supplying an electric charge to the first node throughout a period after the potential of the third node becomes high level until the scanning signal (output signal) at high level is outputted. Here, all of the unit circuits within the shift register have an identical configuration.
1. A shift register configured to perform a shift operation based on a shift clock signal group including a plurality of clock signals, the shift register being configured by a plurality of stages having an identical configuration, wherein
each of unit circuits that respectively constitute the stages includes:
a charge holding node configured to hold an electric charge in order to output an output signal at on level;
an output node configured to output the output signal;
an output control transistor having: a control terminal connected to the charge holding node; a first conducting terminal to which one of the plurality of clock signals included in the shift clock signal group is supplied; and a second conducting terminal connected to the output node; and
a charge supply unit including a charge supply control node that is turned to on level at identical timing with the charge holding node, the charge supply unit being configured to supply an electric charge to the charge holding node throughout a period after a potential of the charge supply control node becomes on level until the output signal at on level is outputted from the output node.
2. The shift register according to claim 1 , wherein
the charge supply unit includes:
a charge supply control node turn-on transistor having: a control terminal to which an output signal outputted from preceding one of the unit circuits is supplied; a first conducting terminal to which one of the outputted signal output from the preceding one of the unit circuits and a direct power-supply voltage at on level is supplied; and a second conducting terminal connected to the charge supply control node; and
a first charge supply control transistor having: a control terminal connected to the charge supply control node; a first conducting terminal to which the direct power-supply voltage at on level is supplied; and a second conducting terminal connected to the charge holding node.
3. The shift register according to claim 2 , wherein the charge supply unit further includes a charge supply control node turn-off transistor having: a control terminal connected to the first conducting terminal of the output control transistor; a first conducting terminal connected to the charge supply control node; and a second conducting terminal to which an off-level voltage is supplied during a period excluding a suspension period in which a clock operation of the plurality of clock signals is suspended.
4. The shift register according to claim 2 , wherein the charge supply unit further includes a second charge supply control transistor having: a control terminal connected to the charge holding node; a first conducting terminal to which the direct power-supply voltage at on level is supplied; and a second conducting terminal connected to the charge supply control node.
5. The shift register according to claim 4 , wherein the charge supply unit further includes a charge supply control node turn-off transistor having: a control terminal to which an output signal outputted from succeeding one of the unit circuits is supplied; a first conducting terminal connected to the charge supply control node; and a second conducting terminal to which an off-level voltage is supplied during a period excluding a suspension period in which a clock operation of the plurality of clock signals is suspended.
6. The shift register according to claim 1 , wherein each of the unit circuits further includes an output-node turn-off transistor having: an control terminal to which an on-level voltage is supplied during a suspension period in which a clock operation of the plurality of clock signals is suspended; a first conducting terminal connected to the output node; and a second conducting terminal to which a direct power-supply voltage at off level is supplied.
7. A display device, comprising:
a display unit having a plurality of scanning signal lines arranged thereon; and
a scanning signal line drive circuit configured to drive the plurality of scanning signal lines, wherein
the scanning signal line drive circuit includes the shift register according to claim 1 having the plurality of stages so as to respectively correspond to the plurality of scanning signal lines one by one.