The present disclosure relates to the technical field of display panels, and in particular, relates to a GOA circuit, a pixel circuit, a display device, and a method for driving a display.
Displays based on an organic light-emitting diode (OLED), a micro LED, and a quantum dot LED all need to be driven by a backplane display circuit having a current output capability. A traditional backplane display circuit is generally formed by single-polarity transistors (or N-type transistors or P-type transistors). The core elements include a pixel array and a gate driver on array (GOA) circuit configured to drive the pixel array. The traditional backplane display circuit is restricted by the single-polarity of the transistors, and encounters some challenges in both the pixel circuit and the GOA circuit.
GOA circuits are widely applied in LCDs, AMOLEDs, and the like electronic display devices. The GOA circuit is a key part of a display panel, and is configured to supply a scanning pulse signal to a pixel array.
A traditional GOA circuit is only capable of supplying scanning pulses having a specific width, and thus fails to accommodate requirement that a pixel circuit having an internal compensation function simultaneously needs scanning pulses having two widths.
The traditional GOA circuit is based on the basic design that a previous stage triggers a following stage, and is generally constituted by a bootstrap capacitor and a single-polarity transistor. Based on this design, the pixel array may only be orderly scanned, but may not be randomly scanned.
When the screen includes n rows of pixels, these pixels are scanned row by row with a refresh frequency of 60 Hz, and a time of 1/60/N is assigned to each row. A capacitive load of a clock line for driving the GOA is proportional to Cgon+Cov*(N−1)+Cpixel. Cgon represents a load contribution of an activated GOA to the clock line, Cov represents a load contribution of the remaining N−1 stages of GOAs to the clock line, and Cpixel represents a load contribution of all the pixels in a row being scanned. When the size of an output transistor of the GOA increases, Cgon and Cov may both increase proportionally.
When the size of the screen constantly increases, the resolution constantly increases, and the pixel density constantly increases, more and more challenges are caused to the GOA circuit as follows:
The number of pixels in each row increases, and the load (Cpixel) of the GOA circuit increases.
The size of the pixels in each row decreases, the available area for the GOA circuit cooperated with the pixels constantly decreases, the size of the transistors for fabricating the GOA circuit is further restricted, and thus the drive capability is degraded.
The increase of the absolute number of rows causes the scanning time for each row to constantly decrease ( 1/60/N). To accommodate more stricter timing requirements, the size of the output transistors of the GOA circuit needs to be increased. This requirement is not only in contradiction with the decrease of the area, but also causes Cgon and Cov to constantly increase.
The increase of the absolute number of rows causes the number of stages (N−1) of the GOA units in a turn-off state to constantly increase, causes the load of the clock lines to correspondingly increase, and cause useless power to increase.
The increase of the absolute number of rows increases the probability that the GOA circuit becomes defective. Once a stage of GOA unit fails, the following stages of GOA units may fail, and consequently, the screen may be damaged.
Due to the above factors, when the traditional GOA circuit structure is applied to screens with constantly increasing size, resolution and pixel density, more and more severe challenges occur, the timing fails to be accommodated, the power consumption constantly increases, and the yield constantly decreases.
In view of the above technical effects, the present disclosure provides a gate driver on array (GOA) circuit, a pixel circuit in cooperation with the GOA circuit, and a display device including the GOA circuit and the pixel circuit.
The present disclosure provides a gate driver on array (GOA) circuit. The GOA circuit includes a plurality of GOA units independent of each other, wherein each of the plurality of GOA units includes an enable module and a drive module disposed corresponding to the enable module; wherein
the enable module includes an address input terminal configured to receive a row address signal, and an enable signal output terminal configured to output an enable signal based on the row address signal; and
the drive module comprises an enable signal input terminal configured to receive the enable signal output by the enable signal output terminal, and a drive signal output terminal configured to output drive signals having different pulse widths based on the enable signal, wherein the drive signal output terminal is connected to a gate line of a row disposed corresponding to the drive module to transmit the drive signal to the gate line of the row and gate the row.
The present disclosure further provides a pixel circuit having an internal compensation effect. The pixel circuit is in cooperation with the GOA circuit as described above. The pixel circuit includes a first transistor T1, a second transistor T2, a third transistor T3, a fourth transistor T4, a fifth transistor T5, a capacitor Cs, a node, and a light-emitting unit; wherein
a second electrode of the first transistor T1 is connected to a data signal, a first electrode of the first transistor T1 is connected to a second electrode of the fourth transistor T4 and a first electrode of the second transistor T2, and a third electrode of the first transistor T1 and a third electrode of the fifth transistor T5 are connected to a second output terminal of a drive module in the GOA circuit; and
a first electrode of the fourth transistor T4 is connected to a high level, a third electrode of the fourth transistor T4 and a third electrode of the third transistor T3 are connected to a first output terminal of the drive module in the GOA circuit, a second electrode of the second transistor T2 and a second electrode of the third transistor T3 are collectively connected to a first electrode of the fifth transistor T5, a second electrode of the fifth transistor T5 is connected to a positive electrode of the light-emitting unit, a negative electrode of the light-emitting unit is connected to a low level, a first electrode of the third transistor T3 is connected to the node and the capacitor Cs in sequence and then connected to a high level, and the node is further connected to a third electrode of the second transistor T2.
The present disclosure further provides a pixel circuit having an internal compensation effect. The pixel circuit is in cooperation with the GOA circuit as described above. The pixel circuit includes a first transistor T1, a second transistor T2, a third transistor T3, a fourth transistor T4, a capacitor Cs, a node, and a light-emitting unit; wherein
a second electrode of the first transistor T1 is connected to a data signal, a first electrode of the first transistor T1 is connected to a second electrode of the fourth transistor T4 and a first electrode of the second transistor T2, and a third electrode of the first transistor T1 is connected to a second output terminal of a drive module in the GOA circuit; and
a first electrode of the fourth transistor T4 is connected to a high level, a third electrode of the fourth transistor T4 and a third electrode of the third transistor T3 are connected to a first output terminal of the drive module in the GOA circuit, a second electrode of the second transistor T2 and a second electrode of the third transistor T3 are collectively connected to a positive electrode of the light-emitting unit, a negative electrode of the light-emitting unit is connected to a low level, a first electrode of the third transistor T3 is connected to the node and the capacitor Cs in sequence and then connected to a high level, and the node is further connected to a third electrode of the second transistor T2.
The present disclosure further provides a display device. The display device includes the GOA circuit as described above and the pixel circuit having the internal compensation effect as described above.
The present disclosure further provides a method for driving a display. The method includes:
inputting an address signal to a row decoder in a gate driver on array (GOA) circuit of a display;
enabling the row decoder corresponding to the address signal;
outputting an enable signal to a pulse generator in the GOA circuit by the enabled row decoder; and
generating a pulse signal by the pulse generator to drive pixels in a corresponding row to operate.
The GOA circuit according to the embodiments of the present disclosure is capable of generating long and short pulse signals configured to drive pixels in various rows, and may be directly cooperated with the pixel circuit. As compared with the conventional GOA circuit only capable of supplying scanning pulses having a single width, the GOA circuit according to the embodiments of the present disclosure is capable of supplying scanning pulses having two different widths that are desired by the pixel circuit having the internal compensation function. That is, the GOA circuit according to the present disclosure is capable of simultaneously generating pulse signals having two different widths, without the need of a doubled circuit area and without increasing a bezel area and power consumption.
The present disclosure provides a GOA circuit supporting random addressing. The GOA circuit allows data to be written into the screen not in accordance with rows. A majority region of the screen displays static images and only a small portion of the screen is constantly varying, and only this portion needs to be programmed. In addition, since the rows with static images are not gated, and thus dynamic power consumption is effectively reduced and meanwhile the time left for each row with varying images, such that real-time and dynamic adjustment may be achieved between display size, display power and display refresh rate.
Further, in the GOA circuit according to the present disclosure, trigger of a later stage does not rely on trigger of a previous stage. Therefore, when a separated-stage GOA unit fails, functions of the remaining GOA units are not affected, such that rating of the screen are improved, thereby providing possibilities of dynamic repair of the screen. In addition, the GOA circuit according to the present disclosure does not employ a traditional bootstrap structure. In some embodiments, a clock line does not need to directly drive an output transistor in the GOA unit. Therefore, impacts caused by (N−1) stages of inactive GOA units to the dynamic power consumption and delay may be greatly mitigated. Therefore, the GOA circuit according to the present disclosure is applicable to high-resolution and large-size screens. Further, the pixel circuit in the display device according to the present disclosure achieves the following merits: The high-drive P-type transistor provides a sufficient light-emitting current and saves the pixel area; the low-drain current N-type transistor maintains voltage data complete, and allows a variable fresh rate; the input drive waveform is simple, and the requirement on the storage capacitor is not high; the light-emitting current is substantially determined by the drive transistor, and is insensitive to OLED aging; the pixel circuit has the internal compensation function, and is capable of compensating for the temporary or permanent fluctuations of the threshold voltage of the high-drive P-type transistor caused by process fluctuations, electrical pressure, material aging, or mechanical stress, such that the life time of the screen is prolonged and the uniformity of the screen is improved.
The present disclosure is further described with reference to the accompanying drawings and exemplary embodiments. Among the drawings:
For clearer descriptions of the technical features, objectives, and the technical effects of the present disclosure, the specific embodiments of the present disclosure are hereinafter described with reference to the accompanying drawings.
As illustrated in
Further, each of the plurality of GOA units 10 further includes a reset module 13 connected to the enable signal output terminal of the enable module 11 and configured to reset the enable module 11 in response to the drive module 12 outputting the drive signal and gating the corresponding row. Each of the plurality of reset modules 13 is disposed corresponding to each row decoder.
After any row decoder of the row decoders outputs an enable signal, and causes the drive module 12 to output a drive signal, the reset modules 13 in this row are all reset, such that a row to which the drive signal is output is reselected when a next row address signal comes in. Specifically, if the enable signal output by the enable module 11 is a high level (1), the reset module 13 may reset the enable signal to a low level (0); and if the enable signal output by the enable module 11 is the low level (0), the reset module 13 resets the enable signal to the high level (1).
The enable module 11 includes a row address signal input terminal configured to receive a row address signal, and an enable signal output terminal configured to output an enable signal based on the row address signal.
Herein, it should be noted that the present disclosure does not limit the source of the address signal. In some embodiments, the row address signal may be generated by an external drive IC. However, in some other embodiments, the row address signal may also be generated by a display screen. For example, when the display screen is capable of providing two types of polarity complementary transistors, a dedicated circuit is designed on the display screen. The dedicated circuit is capable of directly generating the row address signal, and thus the row address signal does not need to be supplied by the external drive IC.
Optionally, the enable module 11 according to the embodiment of the present disclosure is a row decoder based on binary coding, or a row decoder based on Gray coding. Each row decoder includes a plurality of transistors connected in series, wherein two transistors in adjacent rows and in a same column may be combined to a transistor when satisfying a preset condition.
By using the row decoder according to the embodiment of the present disclosure, random addressing may be implemented, data is allowed to be written into the screen not in a row order, and later-stage trigger is not dependent on previous-stage trigger, which effectively improves yield and grade of the screen, and provides possibilities to dynamically repair the screen. In addition, by using the row decoder based on Gray coding, transverse cross lines in the layout may be reduced, more transistors are allowed to be combined, and thus dynamic power consumption is reduced in the mostly commonly used sequential scanning.
Hereinafter, a comparison is made between the row decoder based on sequential coding and the row decoder according to the present disclosure in terms of design.
As illustrated in
As seen from
With respect to the row decoder based on Gray coding according to the present disclosure, as known from the characteristic of Gray coding, two adjacent codes have only one different bit. Therefore, each row decoder according to the present disclosure only needs one transverse cross line. This characteristic is irrelevant to the resolution of the screen. That is, regardless of whether FHD or 4K UHD, when the GOA row decoder according to the present disclosure is employed, only one transverse cross line is needed in each row. A circuit principle diagram of the row decoder based on Gray coding according to a specific embodiment of the present disclosure is as illustrated in
It is herein to be noted that in the principle diagrams in
The fact that two transistors in the adjacent rows and in the same column satisfy the preset condition includes: the gates of the two transistors being shorted together, and each of the two transistors being an uppermost transistor in the row decoder; or gates of the two transistors being shorted together, and upper transistors adjacent to the two transistors having been combined.
Nevertheless, the row decoder according to the present disclosure may also be practiced by a P-type transistor, wherein the practice of the P-type transistor is similar to that of the N-type transistor, and the difference lies in that code 0 corresponds to a positive signal, and code 1 corresponds to a negative signal, and a voltage polarity of the P-type transistor is symmetric to that of the N-type transistor. Specifically, the circuit principle diagram of the row decoder practiced by the P-type transistor is as illustrated in
Likewise, the condition of combination of the transistors in the row decoder practiced by the P-type transistor is the same as that in the row decoder practiced by the N-type transistor, which is not described herein any further.
Further, as illustrated in
Specifically, as illustrated in
As illustrated in
It should be noted herein that the combination may be interpreted as that active regions of the transistors originally pertaining to different rows may be fused in the layout (as illustrated in a gray region (SS) in
Further description is given hereinafter to advantages of the combined row decoder with reference to
As illustrated in
Assuming that an effective resistance after a single transistor is turned on is R in the case of no combination, then an affective resistance after two transistors are combined is lowered to R/2. Therefore, in the case of no combination, a total discharging resistance of each row is 4*R; and in the case of a combination, the total discharging resistance is R*(1+½+¼+⅛)<2*R (geometrical series). In consideration of a screen having 4096 rows, a 14-bit address is desired, and 14 transistors need to be connected in series. In the case of no combination, a total resistance is 14*R; and in the case of a combination, the total resistance is R*(1+½+¼+⅛+ . . . + 1/4096)<2*R. according to the characteristics of the geometrical series, the total discharging resistance upon the combination may not proportionally increase with increase of the number of resolution rows, but an upper limit is defined. Therefore, discharging time, that is, decoding time, is not affected by the increase of the resolution upon the combination. Therefore, with the combination, the row decoder is capable of supporting a high-resolution screen, such that the decoding speed is substantially irrelevant to the increased address line.
The drive module 12 includes an enable signal input terminal connected to the enable signal output terminal of the enable module 11 and configured to receive the enable signal output by the enable signal output terminal, and a drive signal output terminal configured to output a drive signal based on the enable signal, wherein the drive signal output terminal is connected to a gate line of a row disposed corresponding to the drive module 12 to transmit the drive signal to the gate line of the row and gate the row.
Optionally, the drive signal output by the drive module 12 is a pulse signal. The drive module 12 may be a pulse generator.
As a solution, the present disclosure provides a GOA circuit supporting random addressing. The GOA circuit allows data to be written into the screen not in accordance with rows. A majority region of the screen displays static images and only a small portion of the screen is constantly varying, and only this portion needs to be programmed. In addition, since the rows with static images are not gated, and thus dynamic power consumption is effectively reduced and meanwhile the time left for each row with varying images, such that real-time and dynamic adjustment may be achieved between display size, display power and display refresh rate.
Further, in the GOA circuit according to the present disclosure, trigger of a later stage does not rely on trigger of a previous stage. Therefore, when a separated-stage GOA unit 10 fails, functions of the remaining GOA units 10 are not affected, such that yield and rating of the screen are improved, thereby providing possibilities of dynamic repair of the screen. In addition, the GOA circuit according to the present disclosure does not employ a traditional bootstrap structure. A clock line does not need to directly drive an output transistor in the GOA unit. Therefore, impacts caused by (N−1) stages of inactive GOA units to the dynamic power consumption may be greatly mitigated.
Therefore, the GOA circuit according to the present disclosure is applicable to high-resolution and large-size screens.
Two embodiments illustrating the reset module 13 according to the present disclosure are described hereinafter.
As illustrated in
A first electrode of the reset transistor is connected to the enable signal output terminal of the enable module 11, a second electrode of the reset transistor is connected to a ground signal (GND), and a gate of the reset transistor is connected to an external clock signal (CLKR). It should be noted herein that the external clock signal (CLKR) is an additional external clock signal. Further, this embodiment describes the row decoder constituted by the P-type transistors, and when the row decoder is constituted by the N-type transistors, the polarity is reverse to that of the row decoder constituted by the P-type transistors, which is not described herein any further.
As illustrated in
As illustrated in
A non-inverting input terminal (D) of the first-stage positive edge flip-flop 132 and an input terminal of the first-stage inverter 131 are collectively connected to the enable signal output terminal of the enable module 11, an inverting input terminal of the first-stage positive edge flip-flop 132 is connected to an output terminal of the first-stage inverter 131, and a signal clock signal input terminal (CK) of the first-stage positive edge flip-flop 132 and an input terminal of the second-stage inverter 133 are collectively connected to an internal clock signal (CLK). A non-inverting input terminal (D) of the second-stage positive edge flip-flop 134 is connected to a non-inverting output terminal (Q) of the first-stage positive edge flip-flop 132, an inverting input terminal of the second-stage positive edge flip-flop 134 is connected to an inverting output terminal of the first-stage positive edge flip-flop 132, a clock signal input terminal of the second-stage positive edge flip-flop 134 is connected to an output terminal of the second-stage inverter 133, and a non-inverting output terminal (Q) of the second-stage positive edge flip-flop 134 is connected to a gate of the pull-down transistor 135. A first electrode of the pull-down transistor 135 is connected to the enable signal output terminal of the enable module 11, and a second electrode of the pull-down transistor 135 is connected to a ground signal (GND).
In this embodiment, the reset module 13 does not need to additionally reset the clock, and shares the same internal clock signal (CLK) and an inverting signal thereof with a latch at this stage.
As illustrated in
In the embodiments of the present disclosure, the positive edge flip-flop may be practiced in a plurality of ways, which is not specifically limited in the present disclosure. Description is given with reference to a specific embodiment. Specifically, as illustrated in
As illustrated in
An input terminal (S) of the primary flip-flop 1301 is a non-inverting input terminal (D) of the positive edge flip-flop, a non-inverting output terminal of the primary flip-flop 1301 is connected to an input terminal (S) of the secondary flip-flop, a reset terminal (R) of the primary flip-flop is an inverting input terminal of the positive edge flip-flop, and an inverting output terminal of the primary flip-flop 1301 is connected to a reset terminal (R) of the secondary flip-flop 1302. A non-inverting output terminal (Q) of the secondary flip-flop 1302 is a non-inverting output terminal (Q) of the positive edge flip-flop, a clock signal input terminal (CP) of the secondary flip-flop 1302 is connected to an output terminal of the primary/secondary inverter 1303, and a connecting terminal between an input terminal of the primary/secondary inverter 1303 and a clock signal input terminal (CP) of the primary flip-flop 1301 is a clock signal input terminal (CK) of the positive edge flip-flop.
As illustrated in
Two embodiments illustrating the pulse generator according to the present disclosure are described hereinafter.
As illustrated in
The pulse generator includes a first pulse generator 121 and a second pulse generator 122; and the clock signal includes a first clock signal (CLKL) and a second clock signal (CLKS). The gate line of the row disposed corresponding to the drive module 12 includes a first gate line of a row disposed corresponding to the first pulse generator 121 and a second gate line of a row disposed corresponding to the second pulse generator 122.
A data input terminal of the first pulse generator 121 is connected to the first clock signal (CLKL), a clock input terminal of the first pulse generator 121 is connected to the enable signal output terminal (EN) of the enable module 11, and an output terminal (OUTL) of the first pulse generator 121 is connected to the first gate line of the row disposed corresponding to the first pulse generator 121.
A data input terminal of the second pulse generator 122 is connected to the second clock signal (CLKS), a clock input terminal of the second pulse generator 122 is connected to the enable signal output terminal (EN) of the enable module 11, and an output terminal (OUTS) of the second pulse generator 122 is connected to the second gate line of the row disposed corresponding to the second pulse generator 122.
Herein, the data input terminal of the first pulse generator 121 and the data input terminal of the second pulse generator 122 form the data input terminal of the pulse generator, the clock input terminal of the first pulse generator 121 and the clock input terminal of the second pulse generator 122 form the clock input terminal of the pulse generator, and the output terminal of the first pulse generator 121 and the output terminal of the second pulse generator 122 form the output terminal of the pulse generator.
Further, as illustrated in
A first data input terminal (S1) of the first latch is connected to the first clock signal (CLKL), a first enable terminal (CP1) of the first latch is connected to the enable signal output terminal (EN) of the enable module 11, a first output terminal (Q1) of the first latch is connected to an input terminal of the first buffer amplifier, and an output terminal of the first buffer amplifier is connected to the first gate line of the row disposed corresponding to the first pulse generator 121. The first data input terminal (S1) of the first latch is the data input terminal of the first pulse generator 121, the first enable terminal (CP1) of the first latch is the clock input terminal of the first pulse generator 121, and the output terminal of the first buffer amplifier is the output terminal (OUTL) of the first pulse generator 121.
Further, as illustrated in
A second data input terminal (S2) of the second latch is connected to the second clock signal (CLKS), a second enable terminal (CP2) of the second latch is connected to the enable signal output terminal (EN) of the enable module 11, a second output terminal (Q2) of the second latch is connected to an input terminal of the second buffer amplifier, and an output terminal of the second buffer amplifier is connected to the second gate line of the row disposed corresponding to the second pulse generator 122.
The second data input terminal (S2) of the second latch is the data input terminal of the second pulse generator 122, the second enable terminal (CP2) of the second latch is the clock input terminal of the second pulse generator 122, and the output terminal of the second buffer amplifier is the output terminal (OUTS) of the second pulse generator 122.
In
Optionally, the latches employed in the embodiment of the present disclosure are all latches with a gate control function, which operate based on the following principle.
Using latches effective in case of a high level at the enable terminal as an example:
When the enable terminal potential of the latch is a low level, the output terminal of the latch remains unchanged, and a signal of the data input terminal of the latch does not affect the output terminal thereof.
When the enable terminal potential of the latch is a high level, a binary signal of the output terminal of the latch varies with an input potential of the data input terminal of the latch. It may be understood that the latch may be practiced in a plurality of ways, which is not specifically limited in the embodiments of the present disclosure. By employing the latch in each of the plurality of GOA units 10, the present disclosure may achieve the following advantages: Based on the latching principle, internal alternating current signals or glitch signals may be effectively suppressed from being coupled to the output terminal; and in addition, the latch has a waveform reconstruction function, and even if a waveform of an external clock is deformed due to an RC delay, upon the waveform reconstruction, a high-quality square wave pulse may be still output.
The most commonly used latch is an SR-type latch. Herein, two typical embodiments of the SR latch are described.
As illustrated in
An input terminal of the latch inverter 1210 and a first input terminal of the first AND gate 1211 are collectively connected to the internal clock signal (CLK), an output terminal of the latch inverter 1210 is connected to a second input terminal of the second AND gate 1212, and a second input terminal of the first AND gate 1211 and a first input terminal of the second AND gate 1212 are collectively connected to the enable signal output terminal (EN) of the enable module 11. An output terminal of the first AND gate 1211 is connected to a first input terminal of a first NOR gate 1213, a second input terminal of the first NOR gate 1213 is connected to a first input terminal of the second NOR gate 1214, and an output terminal of the first NOR gate 1213 is further connected to the input terminal of the buffer amplifier circuit 122. A second input terminal of the second NOR gate 1214 is connected to an output terminal of the second AND gate 1212.
A connecting terminal between the first input terminal of the first AND gate 1211 and the input terminal of the latch inverter 1210 is the first data input terminal of the first latch, a connecting terminal between the second input terminal of the first AND gate 1211 and the first input terminal of the second AND gate 1212 is the first enable terminal of the first latch, and the output terminal of the first NOR gate 1213 is the first output terminal of the first latch.
Likewise, the second latch may also employ the structure the same as the first latch. For details about the specific structure and connections, reference may be made to the above description, which are not described herein any further. Still likewise, a connecting terminal between the first input terminal of the first AND gate 1211 and the input terminal of the latch inverter 1210 is the second data input terminal of the second latch, a connecting terminal between the second input terminal of the first AND gate 1211 and the first input terminal of the second AND gate 1212 is the second enable terminal of the second latch, and the output terminal of the first NOR gate 1213 is the second output terminal of the second latch.
Further, as illustrated in
An input terminal of the first NOT gate 1201 is connected to a second electrode of the third transistor 1206, an output terminal of the first NOT gate 1201 is connected to a first electrode of the first transistor 1204, a second electrode of the first transistor 1204 is connected to an input terminal of the third NOT gate 1203 and an output terminal of the second NOT gate 1202, a third electrode of the first transistor 1204 is connected to a third electrode of the second transistor 1205 and a third electrode of the third transistor 1206, an output terminal of the third NOT gate 1203 is connected to a first electrode of the second transistor 1205, and a second electrode of the second transistor 1205 is connected to an input terminal of the second NOT gate 1202 and a first electrode of the third transistor 1206.
The input terminal of the first NOT gate 1201 and the second electrode of the third transistor 1206 are the first data input terminal of the first latch, the output terminal of the third NOT gate 1023 is the first output terminal of the first latch, and the third electrode of the first transistor 1204, the third electrode of the second transistor 1205, and the third electrode of the third transistor 1206 are the first enable terminal of the first latch.
In this embodiment, the second latch may also employ the structure the same as the first latch. For details about the specific structure and connections, reference may be made to the above description, which are not described herein any further. Likewise, the input terminal of the first NOT gate 1201 and the second electrode of the third transistor 1206 may also act as the first data input terminal of the second latch, the output terminal of the third NOT gate 1203 may also act as the second output terminal of the second latch, and the third electrode of the first transistor 1204, the third electrode of the second transistor 1205, and the third electrode of the third transistor 1206 may also act as the second enable terminal of the second latch. Likewise, herein, the first transistor and the third transistor are N-type transistors, and the second transistor is a P-type transistor.
The first buffer amplifier and the second buffer amplifier according to the embodiment of the present disclosure may be both constituted by two stages of inverters or a plurality of stages of cascaded inverters.
If the first buffer amplifiers has n stages, n being an odd number greater than or equal to 2, then the first data input terminal (S1) of the first latch is connected to the first clock signal (CLKL), the first enable terminal (CP1) of the first latch is connected to the enable signal output terminal (EN) of the enable module 11, the first output terminal (Q1) of the first latch is connected to an input terminal of a first-stage inverter, and an output terminal of an nth-stage inverter acts as the output terminal (OUTL) of the first buffer amplifier and is connected to the first gate line of the row disposed corresponding to the first pulse generator 121.
If the second buffer amplifiers has n stages, n being an odd number greater than or equal to 2, then the second data input terminal (S2) of the second latch is connected to the second clock signal (CLKS), the second enable terminal (CP2) of the second latch is connected to the enable signal output terminal (EN) of the enable module 11, the second output terminal (Q2) of the second latch is connected to the input terminal of the first-stage inverter, and the output terminal of the nth-stage inverter acts as the output terminal (OUTL) of the second buffer amplifier and is connected to the second gate line of the row disposed corresponding to the second pulse generator 122.
Further, the inverters employed in the plurality of stages of cascaded inverters in the embodiment of the present disclosure may be all constituted by transistors.
Specifically, as illustrated in
Specifically, a first electrode of the P-type transistor is connected to a constant high voltage level (VGH), a second electrode of the P-type transistor is connected to a first electrode of the N-type transistor, a second electrode of the N-type transistor is connected to a constant low voltage level (VGL), a gate of the P-type transistor is connected to a gate of the N-type transistor, and the second electrode of the P-type transistor is connected to a first electrode of the N-type transistor.
The gate of the P-type transistor and the gate of the N-type transistor are the input terminal of the inverter, and the second electrode of the P-type transistor and the first electrode of the N-type transistor are the output terminal of the inverter.
It should be noted that in the embodiment of the present disclosure, a P-type transistor in each of the plurality of GOA units 10 is a P-channel thin film transistor made of low-temperature polysilicon, amorphous silicon, or a material resulted from a mixture of carbon, silicon, and germanium at any ratio. An N-type transistor in each of the plurality of GOA units 10 is an N-channel thin film transistor made of metal oxide. In addition, the GOA circuit according to the present disclosure is a GOA circuit based on polarity complementary transistors. That is, an N-type transistor and a P-type transistor are simultaneously disposed on a panel.
Referring to
As illustrated in
As illustrated in
A first input terminal of the first-stage AND gate is connected to the first clock signal (CLKL), a second input terminal of the first-stage AND gate is connected to the enable signal output terminal (EN) of the enable module 11, an output terminal of the first-stage AND gate is connected to an input terminal of the first buffer amplifier, and an output terminal of the first buffer amplifier is connected to the first gate line of the row disposed corresponding to the first pulse generator 121. The first input terminal of the first-stage AND gate is the data input terminal of the first pulse generator 121, the second input terminal of the first-stage AND gate is the clock input terminal of the first pulse generator 121, and the output terminal of the first buffer amplifier is the output terminal (OUTL) of the first pulse generator 121.
The second pulse generator 122 includes a second-stage AND gate and a second buffer amplifier.
A first input terminal of the second-stage AND gate is connected to the second clock signal (CLKS), a second input terminal of the second-stage AND gate is connected to the enable signal output terminal (EN) of the enable module 11, an output terminal of the second-stage AND gate is connected to an input terminal of the second buffer amplifier, and an output terminal of the second buffer amplifier is connected to the second gate line of the row disposed corresponding to the second pulse generator 122. The first input terminal of the second-stage AND gate is the data input terminal of the second pulse generator 122, the second input terminal of the second-stage AND gate is the clock input terminal of the second pulse generator 122, and the output terminal of the second buffer amplifier is the output terminal (OUTS) of the second pulse generator 122.
As illustrated in
As illustrated in
As described above, various components (the reset module 13, the latch, and the pulse generator) of the GOA circuit according to the embodiment of the present disclosure may have various embodiments. A plurality of possible circuit practice schemes may be reached by arranging and combining the embodiments of the various components. In addition, by these different schemes, a compromise may be made between the area, power consumption, reliability, anti-interference capability, and waveform quality.
Three complete schemes are described hereinafter, and corresponding cascading schemes and timings are provided. In addition, a comparison between a simulation verification result and an operating timing is further provided.
For simplification of the circuit principle diagram, the principle diagram according to the embodiments of the present disclosure only uses a 4-bit address as an example (in this case, the decoder only includes four transistors). The simulation uses an 8-bit address as an example (the address bus is represented by S[0:N]). It should be noted that in practice, the address may be extended to more bits.
In this embodiment, the reset module 13 employs the circuit as described in the second embodiment, and the pulse generator employs the circuit as described in the first embodiment. A single-stage operating timing and a simulation timing are as illustrated in
In this embodiment, the reset module 13 employs the circuit as described in the second embodiment, and the pulse generator employs the circuit as described in the second embodiment. As described above, when the pulse generator according to this embodiment employs the circuit as described in the second embodiment, the AND gate in the initial principle diagram may be replaced by a NOT gate and a NOR gate. It may be understood that in some embodiments, in some processes, the NOR gate may achieve a better circuit performance over the AND gate and the NAND gate, or occupy an even smaller area. A single-stage operating timing and a simulation timing are as illustrated in
In this embodiment, the reset module 13 employs the circuit as described in the second embodiment, and the pulse generator employs the circuit as described in the second embodiment. As compared with the second GOA circuit in
Referring to
The present disclosure provides a GOA circuit supporting random addressing. The GOA circuit allows data to be written into the screen not in accordance with rows. A majority region of the screen displays static images and only a small portion of the screen is constantly varying, and only this portion needs to be programmed. In addition, since the rows with static images are not gated, and thus dynamic power consumption is effectively reduced and meanwhile the time left for each row with varying images, such that real-time and dynamic adjustment may be achieved between display size, display power and display refresh rate.
Further, in the GOA circuit according to the present disclosure, trigger of a later stage does not rely on trigger of a previous stage. Therefore, when a separated-stage GOA unit fails, functions of the remaining GOA units are not affected, such that rating of the screen are improved, thereby providing possibilities of dynamic repair of the screen. In addition, the GOA circuit according to the present disclosure does not employ a traditional bootstrap structure. In some embodiments, a clock line does not need to directly drive an output transistor in the GOA unit. Therefore, impacts caused by (N−1) stages of inactive GOA units to the dynamic power consumption may be greatly mitigated. Therefore, the GOA circuit according to the present disclosure is applicable to high-resolution and large-size screens.
Further, with the GOA circuit according to the present disclosure, the pixel circuit in the display circuit of the display panel achieves the following merits: The high-drive P-type transistor provides a sufficient light-emitting current and saves the pixel area; the low-drain current N-type transistor maintains voltage data complete, and allows a variable fresh rate; the input drive waveform is simple, and the requirement on the storage capacitor is not high; the light-emitting current is substantially determined by the drive transistor, and is insensitive to OLED aging; the pixel circuit has the internal compensation function, and is capable of compensating for the temporary or permanent fluctuations of the threshold voltage of the high-drive P-type transistor caused by process fluctuations, electrical pressure, material aging, or mechanical stress, such that the life time of the screen is prolonged and the uniformity of the screen is improved.
Further, with the pulse generator according to the above embodiment, the GOA circuit according to the embodiments of the present disclosure is capable of generating long and short pulse signals configured to drive pixels in various rows, and may be directly cooperated with the pixel circuit. As compared with the conventional GOA circuit only capable of supplying scanning pulses having a single width, the GOA circuit according to the embodiments of the present disclosure is capable of supplying scanning pulses having two different widths that are desired by the pixel circuit having the internal compensation function, without increasing a bezel area and power consumption.
As illustrated in
As illustrated in
A second electrode of the first transistor T1 is connected to a data signal (Data), a first electrode of the first transistor T1 is connected to a second electrode of the fourth transistor T4 and a first electrode of the second transistor T2, a third electrode of the first transistor T1 and a third electrode of the fifth transistor T5 are connected to a second output terminal of the drive module 12; a first electrode of the fourth transistor T4 is connected to a high level (Vdd), a third electrode of the fourth transistor T4 and a third electrode of the third transistor T3 are connected to a first output terminal of the drive module 12, a second electrode of the second transistor T2 and a second electrode of the third transistor T3 are collectively connected to a first electrode of the fifth transistor T5, a second electrode of the fifth transistor T5 is connected to a positive electrode of the light-emitting unit (OLED), and a negative electrode of the light-emitting unit (OLED) is connected to a low level (Vss); and a first electrode of the third transistor T3 is connected in sequence to the node (nst) and the capacitor Cs and then connected to the high level (Vdd), and the node (nst) is further connected to a third electrode of the second transistor T2.
The third electrode of the fourth transistor T4 and the third electrode of the third transistor T3 are the first gate line of the row disposed corresponding to the first pulse generator 121, and the third electrode of the first transistor T1 and the third electrode of the fifth transistor T5 are the second gate line of the row disposed corresponding to the second pulse generator 122. The first output terminal of the first pulse generator 121 is the first output terminal of the drive module 12, and the second output terminal of the second pulse generator 122 is the second output terminal of the drive module 12.
As illustrated in
Further, an operating timing of the pixel circuit practiced by five transistors and one capacitor (that is, 5T1C) is as illustrated in
At a first stage, when the first pulse signal (En) output by the first pulse generator 121 is a high level, and the second pulse signal (Gn) output by the second pulse generator 122 is a low level, the first transistor T1 and the fourth transistor T4 are turned off, the third transistor T3 and the fifth transistor T5 are turned on, and the node (nst) is discharged to a low level (Vss) via the third transistor T3, the fifth transistor T5, and the light-emitting unit (OLED).
At a second stage, the first transistor T1 is turned on, the data signal (Data) charges the node (nst) via the second transistor T2 and the third transistor T3, and the voltage of the node (nst) is terminated at Vdata−Vt, to sample a threshold voltage of the second transistor T2. Vt is the threshold voltage of the second transistor.
At a third stage, the fourth transistor T4, the second transistor T2, and the fifth transistor T5 are turned on, and the first transistor T1 and the third transistor T3 are turned off. The light-emitting unit (OLED) emits light, the voltage (Vgs) of the second transistor T2 is (Vdd−Vdata+Vt), and thus a compensation effect for Vt is achieved.
Alternatively, in another embodiment, as illustrated in
A second electrode of the first transistor T1 is connected to a data signal (Data), a first electrode of the first transistor T1 is connected to a second electrode of the fourth transistor T4 and a first electrode of the second transistor T2, a third electrode of the first transistor T1 is connected to a second output terminal of the second pulse generator 122; a first electrode of the fourth transistor T4 is connected to a high level (Vdd), a third electrode of the fourth transistor T4 and a third electrode of the third transistor T3 are connected to a first output terminal of the first pulse generator 121, a second electrode of the second transistor T2 and a second electrode of the third transistor T3 are collectively connected to a positive electrode of the light-emitting unit (OLED), and a negative electrode of the light-emitting unit (OLED) is connected to a low level (Vss); and a first electrode of the third transistor T3 is connected in sequence to the node (nst) and the capacitor Cs and then connected to the high level (Vdd), and the node (nst) is further connected to a third electrode of the second transistor T2.
The third electrode of the fourth transistor T4 and the third electrode of the third transistor T3 are the first gate line of the row disposed corresponding to the first pulse generator 121, and the third electrode of the first transistor T1 is the second gate line of the row disposed corresponding to the second pulse generator 122.
In the second embodiment of the pixel circuit, the pixel circuit is practiced by four transistors and one capacitor (that is, 4T1C). A specific operating timing is as illustrated in
Further, in the pixel circuit according to the embodiment of the present disclosure, the first transistor T1 and the third transistor T3 are N-type transistors, and the second transistor T2, the fourth transistor T4, and the fifth transistor T5 are P-type transistors. A P-type transistor in each pixel circuit is a P-channel thin film transistor made of low-temperature polysilicon, amorphous silicon, or a material resulted from a mixture of carbon, silicon, and germanium at any ratio. An N-type transistor in each pixel circuit is an N-channel thin film transistor made of metal oxide.
The pixel circuit in the display device according to the present disclosure achieves the following merits: The high-drive P-type transistor provides a sufficient light-emitting current and saves the pixel area; the low-drain current N-type transistor maintains voltage data complete, and allows a variable fresh rate; the input drive waveform is simple, and the requirement on the storage capacitor is not high; the light-emitting current is substantially determined by the drive transistor, and is insensitive to OLED aging; the pixel circuit has the internal compensation function, and is capable of compensating for the temporary or permanent fluctuations of the threshold voltage of the high-drive P-type transistor caused by process fluctuations, electrical pressure, material aging, or mechanical stress, such that the life time of the screen is prolonged and the uniformity of the screen is improved.
Further, the present disclosure further provides a display device. The display device includes the GOA circuit as described in the above embodiment and a pixel circuit having an internal compensation effect. The display device includes, but is not limited to, an LTPS display device and an AMOLED display device.
step S1, inputting an address signal to each of row decoders in a GOA circuit of the display;
step S2, enabling a row decoder corresponding to the address signal;
step S3,outputting an enable signal to a pulse generator in the GOA circuit by the enabled row decoder; and
step S4, generating a pulse signal by the pulse generator to drive pixels in a corresponding row to operate.
In the embodiment of the present disclosure, the GOA circuit in the method for driving the display may be the GOA circuit as described in the above embodiment.
Further, in the embodiment of the present disclosure, the pulse generator respectively generates a short pulse signal and a long pulse signal, to respectively drive pixels in different rows to operate. That is, the GOA circuit according to the embodiment of the present disclosure is capable of simultaneously generating pulse signals having two widths. It may be understood that the short pulse signal herein is the second pulse signal as described above, and the long pulse signal is the first pulse signal as described above.
Further, the pulse generator further receives the long clock signal and the short clock signal, and generates the long pulse signal and the short pulse signal based on the long clock signal and the short clock signal. It may be understood that the long clock signal herein is the first clock signal (CLKL) as described above, and the short clock signal herein is the second clock signal (CLKS) as described above.
In the embodiment of the present disclosure, the pulse generator may include a first pulse generator and a second pulse generator; wherein the long clock signal is input to a data input terminal of the first pulse generator, the short clock signal is input to a data input terminal of the second pulse generator, and the enable signal is input to a clock input terminal of the first pulse generator and a clock input terminal of the second pulse generator.
Further, the method according to the embodiment of the present disclosure further includes: resetting the enable signal output by the enabled row decoder. Further, resetting the enable signal output by the enabled row decoder may be performed by the reset circuit.
Further, the method for driving the display according to the embodiment of the present disclosure further includes: inputting a long clock signal or a short clock signal to the reset circuit; and resetting, by the reset circuit, the enable signal based on the long clock signal or the short clock signal.
The above embodiments are merely given for illustration of the technical concepts and characteristics of the present disclosure, and are intended to better help persons skilled in the art to understand the content of the present disclosure and practice the technical solutions according to the present disclosure. However, these embodiments are not intended to limit the protection scope of the present disclosure. Any equivalent modifications and polishments made within the protection scope of the appended claims shall be all within the protection scope subject to the appended claims.
It should be understood that persons of ordinary skill in the art may derive improvements or variations according to the above description, and such improvements or variations shall all fall within the protection scope as defined by the claims of the present disclosure.
Number | Date | Country | Kind |
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PCT/CN2018/109648 | Oct 2018 | CN | national |
Number | Date | Country | |
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Parent | PCT/CN2018/120050 | Dec 2018 | US |
Child | 17226846 | US |