WO2020215582A1

WO2020215582A1 - Goa circuit, tft substrate and display device

Info

Publication number: WO2020215582A1
Application number: PCT/CN2019/104372
Authority: WO
Inventors: 奚苏萍; 王添鸿
Original assignee: 深圳市华星光电半导体显示技术有限公司
Priority date: 2019-04-22
Filing date: 2019-09-04
Publication date: 2020-10-29
Also published as: CN109979407B; CN109979407A

Abstract

A GOA circuit, a TFT substrate, and a display device; the GOA circuit comprises a plurality of cascaded GOA units, and an n-level GOA unit comprises: a pull-up control module (21), which is used to input a direct current high voltage VGH1 and to adjust turn-on voltage when an (n-4)-level transmission signal is at a high potential so as to output a stable pull-up control signal Qn, and n>4; and a pull-up module (22), which is used to output a scanning signal Gn of the current level according to the pull-up control signal Qn and a clock signal CKn.

Description

A GOA circuit, TFT substrate and display device

Technical field

The present invention relates to the technical field of display panels, in particular to a GOA circuit, a TFT substrate and a display device.

Background technique

Gate Driver On Array, abbreviated as GOA, is to use the existing thin film transistor liquid crystal display array manufacturing process to fabricate the gate row scan driving signal circuit on the array substrate to realize the driving mode of the gate row scan.

Because GOA technology has the advantages of saving gate chips and realizing narrow edges, and GOA technology has been widely used in panel design, it is particularly necessary to continuously optimize GOA circuits to make GOA performance more stable. However, as shown in FIG. 1, the gate of the thin film transistor T11 in the pull-up control module 11 is connected to the n-4th stage scanning signal G(n-4), and the drain is connected to the n-4th stage transmission signal ST( n-4), when G(n-4) is at a high potential, ST(n-4) is also at a high potential. At this time, T11 is susceptible to current stress, which makes the threshold voltage Vth of T11 deviate greatly , Thereby affecting the stability of the device, thereby affecting the stability of the entire GOA circuit.

technical problem

The embodiments of the present invention provide a GOA circuit, a TFT substrate and a display device to solve the problem of instability of the existing GOA circuit.

Technical solutions

The embodiment of the present invention provides a GOA circuit, which includes a plurality of cascaded GOA units, and the nth level GOA unit includes:

The pull-up control module is used to input DC high voltage, and when the n-4th level transmission signal is at a high potential, adjust the turn-on voltage to output a stable pull-up control signal; n>4;

The pull-up module is used to output the scan signal of the current level according to the pull-up control signal and the clock signal;

The bootstrap module is used to maintain the pull-up control signal at a high potential during the output of the scan signal at this level;

The downstream module is used to output the transmission signal of the current level according to the clock signal and the low potential signal;

The pull-down module is used to pull the pull-up control signal to a low level according to the scan signal of the current level and the n+4th level scan signal;

The pull-down maintenance module is used to maintain the pull-up control signal at a low potential.

Further, the pull-up control module includes a first switch tube;

The pull-up control module is specifically configured to input a high DC voltage, and when the n-4th stage transmission signal is at a high potential, turn on the first switch tube to output a pull-up control signal, and according to the output The pull-up control signal adjusts the conduction voltage of the first switch tube to output a stable pull-up control signal.

Further, the pull-up control module further includes a second switch tube and a third switch tube;

The pull-up control module is specifically configured to input a high DC voltage, turn on the second switch tube, and turn on the first switch tube when the n-4th stage transmission signal is at a high potential to output a high potential The pull-up control signal; when the pull-up control signal is at a high potential, the third switch tube is turned on to reduce the turn-on voltage of the first switch tube and output a stable pull-up control signal.

Further, the control terminal of the second switch tube receives the DC high voltage, the input terminal of the second switch tube receives the n-4th stage transmission signal, and the output terminal of the second switch tube is connected to The control end of the first switch tube;

The input terminal of the first switch tube receives the n-4th stage transmission signal, and the output terminal of the first switch tube outputs the pull-up control signal;

The control terminal of the third switch tube receives the pull-up control signal, the input terminal of the third switch tube receives a low potential signal, and the output terminal of the third switch tube is connected to the control terminal of the first switch tube .

Further, the first switch tube, the second switch tube, and the third switch tube are all thin film transistors; the control terminal is the gate of the thin film transistor, and the input terminal is the source of the thin film transistor, The output terminal is the drain of the thin film transistor.

Further, the size of the second switch tube and the third switch tube are the same.

Further, the DC high voltage is less than the high voltage of the clock signal.

Further, the bootstrap module includes a bootstrap capacitor;

One end of the bootstrap capacitor is connected to the pull-up control signal, and the other end of the bootstrap capacitor receives the scan signal of the current stage.

An embodiment of the present invention also provides a TFT substrate including a GOA circuit; the GOA circuit includes a plurality of cascaded GOA units, and the nth-stage GOA unit includes:

Further, the pull-up control module includes a first switch tube;

Further, the DC high voltage is less than the high voltage of the clock signal.

Further, the bootstrap module includes a bootstrap capacitor;

An embodiment of the present invention also provides a display device, which includes a TFT substrate, the TFT substrate includes a GOA circuit; the GOA circuit includes a plurality of cascaded GOA units, and the nth-level GOA unit includes:

Further, the pull-up control module includes a first switch tube;

Beneficial effect

The beneficial effects of the present invention are: the pull-up control module inputs a high DC voltage, and when the n-4th level transmission signal is at a high potential, the output voltage is adjusted, so that the pull-up control module is less affected by current stress and improves the pull-up Control the stability of the module, thereby improving the stability of the GOA circuit.

Description of the drawings

In order to explain the embodiments or the technical solutions in the prior art more clearly, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are merely inventions For some embodiments, those of ordinary skill in the art can obtain other drawings based on these drawings without creative work.

FIG. 1 is a schematic diagram of the structure of a GOA circuit in the prior art;

FIG. 2 is a schematic structural diagram of a GOA circuit provided by an embodiment of the present invention;

FIG. 3 is a timing diagram of signals in the GOA circuit provided by an embodiment of the present invention.

Embodiments of the invention

The description of the following embodiments refers to the attached drawings to illustrate specific embodiments that the present invention can be implemented. The directional terms mentioned in the present invention, such as [Up], [Down], [Front], [Back], [Left], [Right], [Inner], [Outer], [Side], etc., are for reference only The direction of the additional schema. Therefore, the directional terms used are used to describe and understand the present invention, rather than to limit the present invention. In the figure, units with similar structures are indicated by the same reference numerals.

Refer to Fig. 2, which is a schematic structural diagram of a GOA circuit provided by an embodiment of the present invention.

The GOA circuit provided by the embodiment of the present invention includes a plurality of cascaded GOA units, and the n-th GOA unit includes a pull-up control module 21, a pull-up module 22, a bootstrap module 23, a download module 24, a pull-down module 25, and a pull-down maintenance module. Module 26. Among them, n>4.

The pull-up control module 21 is used to input a DC high voltage VGH1, and when the n-4th stage transmission signal ST(n-4) is at a high potential, adjust the turn-on voltage to output a stable pull-up control signal Qn.

It should be noted that the DC high voltage VGH1 is a separately connected DC signal. After the pull-up control module 21 is turned on, it will output a pull-up control signal Qn, and the pull-up control signal Qn can be used to control the opening and closing of the pull-up module 22.

The pull-up module 22 is connected to the output terminal of the pull-up control module 21, and is used for outputting the current level scanning signal Gn according to the pull-up control signal Qn and the clock signal CKn.

It should be noted that the pull-up control signal Qn output by the pull-up control module 21 is input to the pull-up module 22, and the pull-up module 22 inputs the clock signal CKn, so that the pull-up module 22 will input the clock signal CKn according to the pull-up control signal Qn. The output is the current level scanning signal Gn.

The bootstrap module 23 is connected to the output terminal of the pull-up control module 21, and is used to maintain the pull-up control signal Qn at a high potential during the output period of the scan signal Gn of the current stage.

Further, the bootstrap module 23 includes a bootstrap capacitor Cb;

One end of the bootstrap capacitor Cb is connected to the pull-up control signal Qn, and the other end of the bootstrap capacitor Cb receives the scan signal Gn of the current stage.

The download module 24 is configured to output the transfer signal STn of the current stage according to the clock signal CKn and the low-level signal VSS.

It should be noted that the download module 24 inputs the clock signal CKn, and uses the clock signal CKn to output the stage transfer signal STn according to the low potential signal VSS.

The pull-down module 25 is respectively connected to the output terminal of the pull-up control module 21 and the output terminal of the pull-up module 22, and is used to connect the pull-up control module 21 and the output terminal of the pull-up module 22 according to the current scan signal Gn and the n+4th scan signal G(n+4). The pull control signal Qn is pulled down to the low potential VSS.

The pull-down maintaining module 26 is respectively connected to the control terminals of the pull-down module 25 and the pull-up control module 21, and is used to maintain the pull-up control signal Qn at a low potential.

It should be noted that the pull-down maintaining module 26 accesses the pull-up control signal Qn, outputs the signal Pn, and transmits the signal Pn to the pull-down module 25. When the pull-up control signal Qn is at a low level, the signal Pn is at a high level, the TFT in the pull-down module 25 is turned on, and pulls down and maintains the pull-up control signal Qn at a low level.

Further, as shown in FIG. 2, the pull-up control module 21 includes a first switch tube T11-b;

The pull-up control module 21 is specifically configured to input a DC high voltage VGH1, and when the n-4th stage transmission signal ST(n-4) is at a high potential, turn on the first switching tube T11-b to The pull-up control signal Qn is output, and the turn-on voltage of the first switch tube T11-b is adjusted according to the output pull-up control signal Qn to output a stable pull-up control signal Qn.

It should be noted that the conduction of the pull-up control module 21 specifically refers to the conduction of the first switching tube T11-b. After the first switching tube T11-b is turned on, the pull-up control signal Qn is output, and the pull-up output is output at this time. The potential of the control signal Qn is too high and its electrical properties are unstable. Therefore, adjust the voltage input from the control terminal of the first switch tube T11-b, and then adjust the voltage of the pull-up control signal Qn output by the first switch tube T11-b to make the The pull control signal Qn is at a stable high potential.

Further, as shown in FIG. 2, the pull-up control module 21 further includes a second switching tube T11-a and a third switching tube T11-c;

The pull-up control module 21 is specifically configured to input a high DC voltage VGH1, turn on the second switch tube T11-a, and turn on when the n-4th stage transmission signal ST(n-4) is at a high potential. The first switch tube T11-b outputs a high-level pull-up control signal Qn; when the pull-up control signal Qn is at a high level, the third switch tube T11-c is turned on to reduce the The turn-on voltage of the first switch tube T11-b outputs a stable pull-up control signal Qn.

It should be noted that, in conjunction with Figure 3, the DC high voltage VGH1 is at a high potential, and the input DC high voltage VGH1 makes the second switch tube T11-a turn on. When the input n-4th stage transmission signal ST(n -4) When it is at a high potential, the high potential of the n-4th stage transmission signal ST(n-4) is transmitted to the first switching tube T11-b through the second switching tube T11-a, so that the first switching tube T11- b is turned on, and the pull-up control module 21 outputs a high-potential pull-up control signal Qn. When the pull-up control signal Qn is at a high potential, the third switching tube T11-c is turned on and fed back to the first switching tube T11-b. When the second switching tube T11-a and the third switching tube T11-c are both turned on, through the voltage ratio, the turn-on voltage input to the first switching tube T11-b is reduced but the first switching tube can still be turned on T11-b, so that the first switch tube T11-b receives a smaller current stress and outputs a stable pull-up control signal Qn.

Specifically, as shown in FIG. 2, the control terminal of the second switching tube T11-a receives the DC high voltage VGH1, and the input terminal of the second switching tube T11-a receives the n-4th stage Signal ST(n-4), the output terminal of the second switch tube T11-a is connected to the control terminal of the first switch tube T11-b;

The input terminal of the first switch tube T11-b receives the n-4th stage transmission signal ST(n-4), and the output terminal of the first switch tube T11-b outputs the pull-up control signal Qn ；

The control terminal of the third switch tube T11-c receives the pull-up control signal Qn, the input terminal of the third switch tube T11-c receives a low potential signal VSS, and the output of the third switch tube T11-c The terminal is connected to the control terminal of the first switch tube T11-b.

Further, the first switching tube T11-b, the second switching tube T11-a, and the third switching tube T11-c are all thin film transistors TFT; the control terminal is the gate of the thin film transistor TFT, The input terminal is the source of the thin film transistor TFT, and the output terminal is the drain of the thin film transistor TFT.

In a specific embodiment, the second switching tube T11-a and the third switching tube T11-c have the same size, and the DC high voltage VGH1 is smaller than the high voltage VGH of the clock signal CKn.

It should be noted that the gate of the second switching tube T11-a is connected to the DC high voltage VGH1, and the DC high voltage VGH1 is a voltage lower than VGH, which can completely make the second switching tube T11-a conductive but not As for making the second switch tube T11-a subject to a large current stress, which causes a large Vth offset of the TFT. When the second switching tube T11-a and the third switching tube T11-c are both turned on, since the second switching tube T11-a and the third switching tube T11-c have the same size, that is, the second switching tube T11-a and The on-state resistance of the third switching tube T11-c is the same. According to the principle of resistance voltage division, the voltage divided by the second switching tube T11-a and the third switching tube T11-c is basically the same, making the first switching tube T11-b The gate voltage of the gate is adjusted to (VGH1-VSS)/2, and (VGH1-VSS)/2 is less than VGH1 and far less than VGH, so that the first switch tube T11-b is subject to a smaller current stress, which improves The stability of the pull-up control module 21.

In another specific embodiment, the sizes of the first switching tube T11-b, the second switching tube T11-a, and the third switching tube T11-c are all smaller than the size of the thin film transistor T11 in FIG. , The DC high voltage VGH1 is less than or equal to the high voltage VGH of the clock signal CKn.

It should be noted that since the size of the three switching tubes is smaller than the size of the thin film transistor T11 in FIG. 1, even if the voltage input from the control terminal of the second switching tube T11-a is the same as VGH, the current stress on the three switching tubes will be Relatively small. Therefore, this embodiment not only enables the pull-up control module 21 to complete its original work, but also makes the TFT therein subject to a smaller current stress, thereby effectively reducing the Vth shift of the TFT, improving the stability of the TFT, and thereby improving the overall The stability of GOA circuit.

It can be seen from the above that in the GOA circuit provided in this embodiment, the pull-up control module inputs a high DC voltage, and when the n-4th stage transmission signal is at a high potential, the output voltage is adjusted to reduce the current stress on the pull-up control module The influence of, improve the stability of the pull-up control module, thereby improving the stability of the GOA circuit.

This embodiment also provides a TFT substrate, including the GOA circuit in the above-mentioned embodiment, which will not be described in detail here.

The TFT substrate provided in this embodiment reduces the influence of current stress on the pull-up control module, improves the stability of the pull-up control module, and thereby improves the stability of the GOA circuit.

This embodiment also provides a display device including the TFT substrate in the above embodiment, which will not be described in detail here.

The display device provided by this embodiment reduces the influence of the current stress on the pull-up control module, improves the stability of the pull-up control module, and thereby improves the stability of the GOA circuit.

In summary, although the present invention has been disclosed as above in preferred embodiments, the above-mentioned preferred embodiments are not intended to limit the present invention. Those of ordinary skill in the art can make various modifications without departing from the spirit and scope of the present invention. Such changes and modifications, therefore, the protection scope of the present invention is subject to the scope defined by the claims.

Claims

A GOA circuit, which includes a plurality of cascaded GOA units, and the nth level GOA unit includes:

The pull-up control module is used to input DC high voltage, and when the n-4th level transmission signal is at a high potential, adjust the turn-on voltage to output a stable pull-up control signal; n>4;

The pull-up module is used to output the scan signal of the current level according to the pull-up control signal and the clock signal;

The bootstrap module is used to maintain the pull-up control signal at a high potential during the output of the scan signal at this level;

The downstream module is used to output the transmission signal of the current level according to the clock signal and the low potential signal;

The pull-down module is used to pull the pull-up control signal to a low level according to the scan signal of the current level and the n+4th level scan signal;

The pull-down maintenance module is used to maintain the pull-up control signal at a low potential.
The GOA circuit according to claim 1, wherein the pull-up control module comprises a first switch tube;

The pull-up control module is specifically configured to input a high DC voltage, and when the n-4th stage transmission signal is at a high potential, turn on the first switch tube to output a pull-up control signal, and according to the output The pull-up control signal adjusts the conduction voltage of the first switch tube to output a stable pull-up control signal.
The GOA circuit according to claim 2, wherein the pull-up control module further comprises a second switch tube and a third switch tube;

The pull-up control module is specifically configured to input a high DC voltage, turn on the second switch tube, and turn on the first switch tube when the n-4th stage transmission signal is at a high potential to output a high potential The pull-up control signal; when the pull-up control signal is at a high potential, the third switch tube is turned on to reduce the turn-on voltage of the first switch tube and output a stable pull-up control signal.
The GOA circuit according to claim 3, wherein the control terminal of the second switch tube receives the DC high voltage, and the input terminal of the second switch tube receives the n-4th stage transmission signal, so The output terminal of the second switch tube is connected to the control terminal of the first switch tube;

The input terminal of the first switch tube receives the n-4th stage transmission signal, and the output terminal of the first switch tube outputs the pull-up control signal;

The control terminal of the third switch tube receives the pull-up control signal, the input terminal of the third switch tube receives a low potential signal, and the output terminal of the third switch tube is connected to the control terminal of the first switch tube .
4. The GOA circuit according to claim 4, wherein the first switching tube, the second switching tube and the third switching tube are all thin film transistors; the control terminal is the gate of the thin film transistor, and the The input terminal is the source of the thin film transistor, and the output terminal is the drain of the thin film transistor.
4. The GOA circuit of claim 3, wherein the second switch tube and the third switch tube have the same size.
The GOA circuit according to claim 1, wherein the DC high voltage is less than the high voltage of the clock signal.
The GOA circuit according to claim 1, wherein the bootstrap module comprises a bootstrap capacitor;

One end of the bootstrap capacitor is connected to the pull-up control signal, and the other end of the bootstrap capacitor receives the scan signal of the current stage.
A TFT substrate, which includes a GOA circuit; the GOA circuit includes a plurality of cascaded GOA units, and the nth level GOA unit includes:

The pull-up control module is used to input DC high voltage, and when the n-4th level transmission signal is at a high potential, adjust the turn-on voltage to output a stable pull-up control signal; n>4;

The pull-up module is used to output the scan signal of the current level according to the pull-up control signal and the clock signal;

The bootstrap module is used to maintain the pull-up control signal at a high potential during the output of the scan signal at this level;

The downstream module is used to output the transmission signal of the current level according to the clock signal and the low potential signal;

The pull-down module is used to pull the pull-up control signal to a low level according to the scan signal of the current level and the n+4th level scan signal;

The pull-down maintenance module is used to maintain the pull-up control signal at a low potential.
9. The TFT substrate of claim 9, wherein the pull-up control module comprises a first switch tube;

The pull-up control module is specifically configured to input a high DC voltage, and when the n-4th stage transmission signal is at a high potential, turn on the first switch tube to output a pull-up control signal, and according to the output The pull-up control signal adjusts the conduction voltage of the first switch tube to output a stable pull-up control signal.
11. The TFT substrate of claim 10, wherein the pull-up control module further comprises a second switch tube and a third switch tube;

The pull-up control module is specifically configured to input a high DC voltage, turn on the second switch tube, and turn on the first switch tube when the n-4th stage transmission signal is at a high potential to output a high potential The pull-up control signal; when the pull-up control signal is at a high potential, the third switch tube is turned on to reduce the turn-on voltage of the first switch tube and output a stable pull-up control signal.
11. The TFT substrate of claim 11, wherein the control terminal of the second switch tube receives the DC high voltage, and the input terminal of the second switch tube receives the n-4th stage transmission signal, so The output terminal of the second switch tube is connected to the control terminal of the first switch tube;

The input terminal of the first switch tube receives the n-4th stage transmission signal, and the output terminal of the first switch tube outputs the pull-up control signal;

The control terminal of the third switch tube receives the pull-up control signal, the input terminal of the third switch tube receives a low potential signal, and the output terminal of the third switch tube is connected to the control terminal of the first switch tube .
The TFT substrate according to claim 12, wherein the first switching tube, the second switching tube and the third switching tube are all thin film transistors; the control terminal is the gate of the thin film transistor, and the The input terminal is the source of the thin film transistor, and the output terminal is the drain of the thin film transistor.
11. The TFT substrate of claim 11, wherein the second switch tube and the third switch tube have the same size.
9. The TFT substrate of claim 9, wherein the DC high voltage is less than the high voltage of the clock signal.
9. The TFT substrate according to claim 9, wherein the bootstrap module comprises a bootstrap capacitor;

One end of the bootstrap capacitor is connected to the pull-up control signal, and the other end of the bootstrap capacitor receives the scan signal of the current stage.
A display device includes a TFT substrate, the TFT substrate includes a GOA circuit; the GOA circuit includes a plurality of cascaded GOA units, and the nth-level GOA unit includes:

The pull-up control module is used to input DC high voltage, and when the n-4th level transmission signal is at a high potential, adjust the turn-on voltage to output a stable pull-up control signal; n>4;

The pull-up module is used to output the scan signal of the current level according to the pull-up control signal and the clock signal;

The bootstrap module is used to maintain the pull-up control signal at a high potential during the output of the scan signal at this level;

The downstream module is used to output the transmission signal of the current level according to the clock signal and the low potential signal;

The pull-down module is used to pull the pull-up control signal to a low level according to the scan signal of the current level and the n+4th level scan signal;

The pull-down maintenance module is used to maintain the pull-up control signal at a low potential.
The display device according to claim 17, wherein the pull-up control module comprises a first switch tube;

The pull-up control module is specifically configured to input a high DC voltage, and when the n-4th stage transmission signal is at a high potential, turn on the first switch tube to output a pull-up control signal, and according to the output The pull-up control signal adjusts the conduction voltage of the first switch tube to output a stable pull-up control signal.
18. The display device of claim 18, wherein the pull-up control module further comprises a second switch tube and a third switch tube;

The pull-up control module is specifically configured to input a high DC voltage, turn on the second switch tube, and turn on the first switch tube when the n-4th stage transmission signal is at a high potential to output a high potential The pull-up control signal; when the pull-up control signal is at a high potential, the third switch tube is turned on to reduce the turn-on voltage of the first switch tube and output a stable pull-up control signal.
18. The display device according to claim 19, wherein the control terminal of the second switch tube receives the DC high voltage, and the input terminal of the second switch tube receives the n-4th stage transmission signal, so The output terminal of the second switch tube is connected to the control terminal of the first switch tube;

The input terminal of the first switch tube receives the n-4th stage transmission signal, and the output terminal of the first switch tube outputs the pull-up control signal;

The control terminal of the third switch tube receives the pull-up control signal, the input terminal of the third switch tube receives a low potential signal, and the output terminal of the third switch tube is connected to the control terminal of the first switch tube .