Shift register, scanning signal line drive circuit provided with same, and display device
An object is shortening a clock fall-rise period while suppressing an increase in a circuit area, an increase in current consumption, and a cost increase, without generating an abnormal operation, in a shift register within a monolithic gate driver. In a shift register ( 410 ) that operates based on four-phase clock signals, including two-phase clock signals (GCK 1 , GCK 3 ) that are provided to odd-order stages and two-phase clock signals (GCK 2 , GCK 4 ) that are provided to even-order stages, of which phases are shifted by 90 degrees from each other, a potential of a first clock (CKA) appears as a potential of a scanning signal (GOUT), when a potential of a first node is at a high level, in each stage. In this configuration, the potential of the first node included in each stage is set to a high level based on a pulse of a scanning signal outputted from a pre-stage, and is set to a low level based on a pulse of a scanning signal outputted from a third stage after a stage concerned.
1. A shift register comprising a plurality of bistable circuits each having a first state and a second state and connected in series with each other, in which the plurality of bistable circuits sequentially become in the first state based on at least four-phase clock signals including two-phase clock signals which are provided as a first clock signal and a second clock signal to odd-order stage bistable circuits out of the plurality of bistable circuits, and two-phase clock signals which are provided as the first clock signal and the second clock signal to even-order stage bistable circuits out of the plurality of bistable circuits, wherein
each bistable circuit includes:
an output node that outputs a state signal indicating either one of the first state and the second state;
an output-control switching element in which the first clock signal is provided to a second electrode, and a third electrode is connected to the output node;
a first-node charge unit for charging a first node connected to a first electrode of the output-control switching element based on a state signal outputted from a bistable circuit of a pre-stage or a stage before the pre-stage of each bistable circuit concerned; and
a first-node discharge unit for discharging the first node based on a state signal outputted from a bistable circuit of a third stage after each bistable circuit concerned.
2. The shift register according to claim 1 , wherein a phase of the first clock signal and a phase of the second clock signal are shifted by 180 degrees from each other.
3. The shift register according to claim 1 , wherein a phase of two-phase clock signals provided to the odd-order stage bistable circuits and a phase of two-phase clock signals provided to the even-order stage bistable circuits are shifted by 90 degrees from each other.
4. The shift register according to claim 1 , wherein a timing when the first clock signal changes from a high level to a low level is the same as a timing when the second clock signal changes from a low level to a high level, and also a timing when the first clock signal changes from the low level to the high level is the same as a timing when the second clock signal changes from the high level to the low level.
5. The shift register according to claim 1 , wherein on-duty of each of the four-phase clock signals is 50%.
6. The shift register according to claim 1 , wherein
in each bistable circuit,
the first-node charge unit includes a first switching element in which a state signal outputted from a pre-stage bistable circuit of each bistable circuit concerned is provided to a first electrode and a second electrode, and a third electrode is connected to the first node, and
the first-node discharge unit includes a second switching element in which a state signal outputted from a bistable circuit of a third stage after each bistable circuit concerned is provided to a first electrode, a second electrode is connected to the first node, and a low-level potential is provided to a third electrode.
7. The shift register according to claim 1 , wherein
each bistable circuit further includes:
a third switching element in which a second electrode is connected to the first node, and a low-level potential is provided to a third electrode; and
a second node control unit that controls a potential of a second node connected to a first electrode of the third switching element, based on the second clock signal and a potential of the first node.
8. The shift register according to claim 7 , wherein
the second node control unit includes:
a fourth switching element in which the second clock signal is provided to a first electrode and a second electrode, and a third electrode is connected to the second node; and
a fifth switching element in which a first electrode is connected to the first node, a second electrode is connected to the second node, and a low-level potential is provided to a third electrode.
9. The shift register according to claim 1 , wherein
the odd-order stage bistable circuits receive one of two-phase clock signals that are provided to the even-order stage bistable circuits, as a third clock signal,
the even-order stage bistable circuits receive one of two-phase clock signals that are provided to the odd-order stage bistable circuits, as the third clock signal, and
each bistable circuit further includes
a third switching element in which a second electrode is connected to the first node, and a low-level potential is provided to a third electrode, and
a second-node control unit that controls a potential of a second node connected to a first electrode of the third switching element, based on the third clock signal and a potential of the first node.
10. The shift register according to claim 9 , wherein
the second node control unit includes:
a fourth switching element in which the third clock signal is provided to a first electrode and a second electrode, and a third electrode is connected to the second node; and
a fifth switching element in which a first electrode is connected to the first node, a second electrode is connected to the second node, and a low-level potential is provided to a third electrode.
11. The shift register according to claim 7 , wherein
in each bistable circuit, the second node control unit further includes a sixth switching element in which a state signal outputted from a next-stage bistable circuit of each bistable circuit concerned is provided to a first electrode, a second electrode is connected to the second node, and a low-level potential is provided to a third electrode.
12. The shift register according to claim 7 , wherein
each bistable circuit further includes a second first-node charge unit for charging the first node based on a state signal outputted from a next-stage bistable circuit of each bistable circuit concerned.
13. The shift register according to claim 12 , wherein
in each bistable circuit, the second first-node charge unit includes a seventh switching element in which a state signal outputted from a next-stage bistable circuit of each bistable circuit concerned is provided to a first electrode and a second electrode, and a third electrode is connected to the first node.
14. The shift register according to claim 1 , wherein each bistable circuit further includes an eighth switching element in which the second clock signal is provided to a first electrode, a second electrode is connected to the output node, and a low-level potential is provided to a third electrode.
15. The shift register according to claim 1 , wherein each bistable circuit further includes a capacitor in which one end is connected to the first node, and the other end is connected to the output node.
16. The shift register according to claim 1 , wherein
each bistable circuit further includes a ninth switching element in which a state signal outputted from a bistable circuit of a second stage or a third stage after each bistable circuit concerned is provided to a first electrode, a second electrode is connected to the output node, and a low-level potential is provided to a third electrode.
17. The shift register according to claim 1 , wherein
three scanning end signals for discharging the first node that is included in each of bistable circuits of a last-stage, a stage before the last stage, and a second stage before the last stage out of the plurality of bistable circuits, by the first-node discharge unit respectively, are provided from an outside.
18. The shift register according to claim 17 , wherein
at least two scanning end signals out of the three scanning end signals are realized by one signal.
19. The shift register according to claim 18 , wherein
in each of bistable circuits of a last-stage, a stage before the last stage, and a second stage before the last stage out of the plurality of bistable circuits, a change of the first clock signal from a low level to a high level is suppressed, during a period until the first node is discharged by the first-node discharge unit, after the first node is charged by the first-node charge unit.
20. The shift register according to claim 17 , wherein
any one of bistable circuits of a last-stage, a stage before the last stage, and a second stage before the last stage out of the plurality of bistable circuits includes a tenth switching element in which the scanning end signal is provided to a first electrode, a second electrode is connected to the output node, and a low-level potential is provided to a third electrode.
21. The shift register according to claim 1 , wherein the shift register is formed by using amorphous silicon.
22. The shift register according to claim 1 , wherein the shift register is formed by using microcrystalline silicon.
23. The shift register according to claim 1 , wherein the shift register is formed by using polycrystalline silicon.
24. The shift register according to claim 1 , wherein the shift register is formed by using an oxide semiconductor.
25. A scanning signal line drive circuit of a display device, for driving a plurality of scanning signal lines that are provided in a display unit, comprising:
the shift register according to claim 1 , wherein
the plurality of bistable circuits are provided so as to have a one-to-one correspondence with the plurality of scanning signal lines, and
each bistable circuit provides a state signal outputted from the output node, to a scanning signal line corresponding to each bistable circuit concerned as a scanning signal.
26. A display device comprising the scanning signal line drive circuit according to claim 25 , including the display unit.
27. The display device according to claim 26 , wherein a shift register including the plurality of bistable circuits is provided at both one end side and the other end side of the display unit, respectively.
28. The display device according to claim 26 , wherein the odd-order stage bistable circuits are provided at one end side of the display unit, and the even-order stage bistable circuits are provided at the other end side of the display unit.