Pixel Circuit and Display Panel

Abstract

The present application discloses a pixel circuit and a display panel, wherein the pixel circuit includes a driving transistor, a light-emitting device, a feedback transistor and a feedback capacitor. By coupling the feedback transistor and the feedback capacitor in series between the gate of the driving transistor and the anode of the light-emitting device, the gate potential of the driving transistor and the anode potential of the light-emitting device can be controlled to change in linkage, which can not only more stably control the light-emitting current flowing through the light-emitting device through the gate potential of the driving transistor and the anode potential of the light-emitting device after the linkage change, thereby reducing the brightness change of the light-emitting device; it can also control the anode potential of the light-emitting device to reach the start-up voltage earlier, thereby increasing the effective light-emitting time or improving the light-emitting brightness of the light-emitting device.

Description

Technical Field

[0001] The present application relates to the field of display technologies, and particularly to a pixel circuit and a display panel. Background Art

[0002] AMOLED (Active Matrix Organic Light Emitting Diode) display technology is increasingly widely used, and its usage proportion in mobile phones, wearables, laptop computers, and tablet computers is getting higher and higher. With the development of products, under the technical application requirements of higher PPI (Pixels Per Inch) and high and low frequency display switching, the applicant has found that display quality instability is likely to occur during frequency switching, such as color deviation during frequency switching at low gray levels.

[0003] As the working duration of the pixel circuit or the display panel increases, or as the working duration in a high-temperature and high-humidity environment increases, it usually leads to unstable brightness of the light-emitting devices in the pixel circuit, affecting the display quality. Summary of the Invention

[0004] The present application provides a pixel circuit and a display panel to alleviate the technical problem of unstable brightness of the light-emitting devices.

[0005] In a first aspect, the present application provides a pixel circuit, which includes a driving transistor, a light-emitting device, a feedback transistor, and a feedback capacitor. One of the source or drain of the driving transistor is electrically connected to a first power supply line; the anode of the light-emitting device is electrically connected to the other of the source or drain of the driving transistor, and the cathode of the light-emitting device is electrically connected to a second power supply line; the gate of the feedback transistor is electrically connected to a first control line; the feedback capacitor and the feedback transistor are connected in series between the gate of the driving transistor and the anode of the light-emitting device.

[0006] In some embodiments, one end of the feedback capacitor is electrically connected to a first initialization line, and the first initialization line receives a first initialization signal; the other end of the feedback capacitor is electrically connected to a second initialization line, and the second initialization line receives a second initialization signal; the feedback transistor is connected in series between the feedback capacitor and the first initialization line or the second initialization line; the potential of the first initialization signal is different from the potential of the second initialization signal.

[0007] In some embodiments, the pixel circuit further includes a first initialization transistor and a second initialization transistor. The first initialization transistor is connected in series between one end of the feedback capacitor and the first initialization line, and the gate of the first initialization transistor is electrically connected to a second control line; the second initialization transistor is connected in series between the other end of the feedback capacitor and the second initialization line, and the gate of the second initialization transistor is electrically connected to the second control line.

[0008] In some embodiments, the pixel circuit further includes a first light-emitting control transistor, a second light-emitting control transistor, a writing transistor, and a compensation transistor. One of the source or drain of the first light-emitting control transistor is electrically connected to the other of the source or drain of the driving transistor. The other of the source or drain of the first light-emitting control transistor is electrically connected to the anode of the light-emitting device. The gate of the first light-emitting control transistor is electrically connected to the light-emitting control line. One of the source or drain of the second light-emitting control transistor is electrically connected to the first power supply line. The other of the source or drain of the second light-emitting control transistor is electrically connected to one of the source or drain of the driving transistor. The gate of the second light-emitting control transistor is electrically connected to the light-emitting control line. One of the source or drain of the writing transistor is electrically connected to the data line. The other of the source or drain of the writing transistor is electrically connected to one of the source or drain of the driving transistor. The gate of the writing transistor is electrically connected to the third control line. One of the source or drain of the compensation transistor is electrically connected to the other of the source or drain of the driving transistor. The other of the source or drain of the compensation transistor is electrically connected to the gate of the driving transistor. The gate of the compensation transistor is electrically connected to the fourth control line.

[0009] In some embodiments, during the initialization stage of the pixel circuit, the first initialization transistor and the second initialization transistor are both in the conducting state, and the feedback transistor is in the conducting state for at least part of the first stage, so as to reset the gate potential of the driving transistor and one end potential of the feedback capacitor through the first initialization signal, and reset the anode potential of the light-emitting device and the other end potential of the feedback capacitor through the second initialization signal.

[0010] In some embodiments, during the data writing stage of the pixel circuit, the data signal raises the anode potential of the light-emitting device through the series-connected feedback transistor and feedback capacitor, and the anode potential of the light-emitting device is less than the turn-on voltage of the light-emitting device.

[0011] In some embodiments, during the light-emitting stage of the pixel circuit, the gate potential of the driving transistor changes in the opposite direction to the anode potential of the light-emitting device through the series-connected feedback transistor and feedback capacitor.

[0012] In some embodiments, during the blanking stage of the pixel circuit, the gate potential of the driving transistor is raised and the anode potential of the light-emitting device is lowered through the series-connected feedback transistor and feedback capacitor.

[0013] In some embodiments, the first control line is used to transmit a first control signal, and the light-emitting control line is used to transmit a light-emitting control signal; the frequency of the first control signal is greater than the frequency of the light-emitting control signal.

[0014] In a second aspect, the present application provides a display panel, which includes multiple pixel circuits of at least one of the above-mentioned embodiments, each pixel circuit also includes a storage capacitor, one end of the storage capacitor is electrically connected to the gate of the driving transistor, and the other end of the storage capacitor is electrically connected to the first power line.

[0015] The pixel circuit and display panel provided in the present application can control the linkage change of the gate potential of the driving transistor and the anode potential of the light-emitting device by coupling a feedback transistor and a feedback capacitor in series between the gate of the driving transistor and the anode of the light-emitting device. Not only can the light-emitting current flowing through the light-emitting device be more stably controlled by the gate potential of the driving transistor and the anode potential of the light-emitting device after the linkage change, thereby reducing the brightness change of the light-emitting device; it can also control the anode potential of the light-emitting device to reach the start-up voltage earlier, thereby increasing the effective light-emitting time or improving the light-emitting brightness of the light-emitting device.

[0016] Furthermore, since the light-emitting currents flowing through the light-emitting devices in different pixel circuits are closer to unity, the light-emitting brightness of different light-emitting devices is more uniform, which can improve the color cast of the display panel, for example, green cast. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The technical solution and other beneficial effects of the present application will be made apparent by describing in detail the specific implementation methods of the present application in conjunction with the accompanying drawings.

[0018] Figure 1 It is a schematic diagram for comparing low grayscale images before and after reliability testing in the related art.

[0019] Figure 2 It is a schematic diagram of the structure of leakage current between different pixel circuits in the related art.

[0020] Figure 3 A schematic diagram comparing the changes in anode potential of light-emitting devices of different colors in the related art.

[0021] Figure 4 A schematic diagram of the structure of a pixel circuit provided in an embodiment of the present application.

[0022] Figure 5 for Figure 4 Timing diagram of the pixel circuit shown.

[0023] Figure 6 A schematic diagram of the state of a pixel circuit in the first stage of a frame provided by an embodiment of the present application.

[0024] Figure 7 A schematic diagram of the state of a pixel circuit in the second stage of a frame provided by an embodiment of the present application.

[0025] Figure 8Schematic diagram of the state of the pixel circuit provided by the embodiment of the present application in the third stage of a frame.

[0026] Figure 9 Schematic diagram of the state of the pixel circuit provided by the embodiment of the present application in the third sub-stage of the third stage.

[0027] Figure 10 For Figure 9 Schematic diagram of the linked change between the potential at point Q and the potential at point C in the third sub-stage shown.

[0028] Figure 11 Schematic diagram of the state of the pixel circuit provided by the embodiment of the present application in the fourth stage of a frame.

[0029] Figure 12 Another structural schematic diagram of the pixel circuit provided by the embodiment of the present application. Detailed implementation manners

[0030] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts belong to the scope of protection of the present application.

[0031] There are situations where the display screen has greenish low gray levels or color deviation in low gray level frequency switching. Since the display color deviation is affected by various factors, the inventor found through a large amount of analysis and experiments that the cause of this defect is due to device aging. Specifically, as Figure 1 shown in the comparison schematic diagram of the low gray level screen before and after the reliability test in the related art, Figure 1 the first picture from left to right in it is the low gray level screen before the RA (Reliability) test, and its color data determined based on CIE1976 of the International Commission on Illumination (CIE) is (0.303, 0.326), and the corresponding luminance (Luminance, Lum.) is 0.025nits; Figure 1 the second picture from left to right in it is the low gray level screen after the RA test, and its color data determined based on the International Commission on Illumination is (0.334, 0.431), and the corresponding luminance is 0.039nits.

[0032] Figure 1 the third picture from left to right in it is the low gray level screen before the RA test, and its color data determined based on the International Commission on Illumination is (0.289, 0.291), and the corresponding luminance is 0.021nits;Figure 1 The fourth picture from left to right is a low gray-scale picture after the RA test. Based on the color data determined by the International Commission on Illumination, it is (0.321, 0.562), and the corresponding brightness is 0.092 nits.

[0033] Among them, the first picture and the second picture use the same video data, and the third picture and the fourth picture use the same video data. However, after the RA test, compared with the first picture, the displayed color of the second picture is greener; similarly, compared with the third picture, the displayed color of the fourth picture is also greener.

[0034] It should be noted that the above RA test can be at least one of long-term normal operation, short-term operation under high temperature and high humidity, or high temperature operation (HTO, High Temperature Operation).

[0035] The inventor further analyzed and experimented on multiple factors affecting the aging test and found that this phenomenon is caused by the leakage current between different pixel circuits. Under normal circumstances, this effect is very small and will not have a great impact. However, as the pixel density increases, the distance between pixels also becomes smaller. At low gray-scale switching frequencies, the effect becomes prominent. The specific reason is as Figure 2 shown in the schematic diagram of the leakage current structure between different pixel circuits in the related technology. The reason for the appearance of Figure 1 the phenomenon shown is that after the RA test, the change degrees of the self-capacitances of light-emitting devices of different colors are different, resulting in a difference between the self-capacitances of light-emitting devices of different colors. Furthermore, it causes leakage current (I off ) from the anode of a light-emitting device of other colors (for example, red R) to the anode of a green (G) light-emitting device. Then, the light-emitting current flowing through the green light-emitting device increases, resulting in the overall picture color being greener.

[0036] In addition, during the operation of the pixel circuit, the anode of the light-emitting device needs to be charged first, and the light-emitting device can emit light only after the anode potential reaches its own turn-on voltage.

[0037] Specifically, as Figure 3 shown, Figure 3Schematic diagram for comparing the anode potential changes of light-emitting devices of different colors in the related art. Here, the abscissa represents time, the ordinate represents the anode potential of the light-emitting device, R@Vth represents the turn-on voltage of the red light-emitting device, G@Vth represents the turn-on voltage of the green light-emitting device, RS1 represents the curve of the anode potential of the red light-emitting device changing with time before RA, RS2 represents the curve of the anode potential of the red light-emitting device changing with time after RA, GS1 represents the curve of the anode potential of the green light-emitting device changing with time before RA, and GS2 represents the curve of the anode potential of the green light-emitting device changing with time after RA.

[0038] It is found through comparison that after RA, the anode potential of the red light-emitting device takes a longer time to reach its own turn-on voltage, and the anode potential of the green light-emitting device also takes a longer time to reach its own turn-on voltage. This reduces the effective light-emitting time of each light-emitting device, which is also one of the reasons for the unstable brightness of each light-emitting device.

[0039] It can be understood that any of the above light-emitting devices, whether it is an organic light-emitting diode, a mini light-emitting diode, a micro light-emitting diode, or a quantum dot light-emitting diode, has its own capacitance, and the difference lies in the different sizes after aging. The improvement scheme and principle provided in this application can be applied to any of the above-mentioned light-emitting diodes, especially obvious in organic light-emitting materials.

[0040] In view of the above-mentioned technical problem of the unstable brightness of the light-emitting device, this embodiment provides a pixel circuit. Please refer to Figures 4 to 12 , as Figure 4 , Figure 12 shown. The pixel circuit includes a driving transistor T1, a light-emitting device D1, a feedback transistor T8, and a feedback capacitor C1. One of the source or drain of the driving transistor T1 is electrically connected to the first power supply line; the anode of the light-emitting device D1 is electrically connected to the other of the source or drain of the driving transistor T1, and the cathode of the light-emitting device D1 is electrically connected to the second power supply line; the gate of the feedback transistor T8 is electrically connected to the first control line; the feedback capacitor C1 and the feedback transistor T8 are connected in series between the gate of the driving transistor T1 and the anode of the light-emitting device D1.

[0041] It can be understood that the pixel circuit provided in this embodiment can control the gate potential of the driving transistor T1 and the anode potential of the light-emitting device D1 to change in linkage by coupling the feedback transistor T8 and the feedback capacitor C1 in series between the gate of the driving transistor T1 and the anode of the light-emitting device D1. Not only can the light-emitting current flowing through the light-emitting device D1 be more stably controlled by the gate potential of the driving transistor T1 and the anode potential of the light-emitting device D1 after the linkage change, thereby reducing the brightness change of the light-emitting device D1; it can also control the anode potential of the light-emitting device D1 to reach the start-up voltage earlier, thereby increasing the effective light-emitting time or improving the light-emitting brightness of the light-emitting device D1.

[0042] In one embodiment, if Figure 4 , Figure 8 As shown, one end of the feedback capacitor C1 is electrically connected to the first initialization line, and the first initialization line receives the first initialization signal Vi_G; the other end of the feedback capacitor C1 is electrically connected to the second initialization line, and the second initialization line receives the second initialization signal Vi_Ano; the feedback transistor is connected in series between the feedback capacitor C1 and the first initialization line or the second initialization line; the potential of the first initialization signal Vi_G is different from the potential of the second initialization signal Vi_Ano.

[0043] It should be noted that in this embodiment, the first initialization line and the second initialization line can respectively initialize the potential of one end of the feedback capacitor C1 and the potential of the other end of the feedback capacitor C1 to corresponding different potentials, so as to accurately control the voltage difference between the gate of the driving transistor T1 and the anode of the light-emitting device D1 of the feedback capacitor C1.

[0044] In one embodiment, if Figure 4 As shown, one of the source or drain of the feedback transistor T8 is electrically connected to the gate of the driving transistor T1; one end of the feedback capacitor C1 is electrically connected to the other of the source or drain of the feedback transistor T8, and the other end of the feedback capacitor C1 is electrically connected to the anode of the light emitting device D1.

[0045] It should be noted that, through the conduction period of the feedback transistor T8, the period in which the gate potential of the driving transistor T1 and the anode potential of the light-emitting device D1 are linked to change can be selected, and then the anode potential of the light-emitting device D1 can be pre-charged through the gate potential of the driving transistor T1 to reach the start-up voltage earlier; the gate potential of the driving transistor T1 and the anode potential of the light-emitting device D1 can also be linked to change to stabilize the gate potential of the driving transistor T1 and / or the anode potential of the light-emitting device D1, so as to more stably control the light-emitting current flowing through the light-emitting device D1 and reduce the brightness change of the light-emitting device D1.

[0046] In one embodiment, if Figure 12As shown, one end of the feedback capacitor C1 is electrically connected to the gate of the driving transistor T1; one of the source or drain of the feedback transistor T8 is electrically connected to the other end of the feedback capacitor C1, and the other of the source or drain of the feedback transistor T8 is electrically connected to the anode of the light emitting device D1.

[0047] It should be noted that the present embodiment can also select the period during which the gate potential of the driving transistor T1 and the anode potential of the light-emitting device D1 are linked to each other through the conduction period of the feedback transistor T8, and then the anode potential of the light-emitting device D1 can be pre-charged through the gate potential of the driving transistor T1 to reach the start-up voltage earlier; the gate potential of the driving transistor T1 and the anode potential of the light-emitting device D1 can also be linked to each other to stabilize the gate potential of the driving transistor T1 and / or the anode potential of the light-emitting device D1, so as to more stably control the light-emitting current flowing through the light-emitting device D1 and reduce the brightness change of the light-emitting device D1.

[0048] In one embodiment, the pixel circuit further includes a first initialization transistor T4 and a second initialization transistor T7, one of the source or the drain of the first initialization transistor T4 is electrically connected to the first initialization line, the other of the source or the drain of the first initialization transistor T4 is electrically connected to the gate of the driving transistor T1, and the gate of the first initialization transistor T4 is electrically connected to the second control line; one of the source or the drain of the second initialization transistor T7 is electrically connected to the second initialization line, the other of the source or the drain of the second initialization transistor T7 is electrically connected to the anode of the light-emitting device D1, and the gate of the second initialization transistor T7 is electrically connected to the second control line.

[0049] It should be noted that the first initialization line can initialize the gate potential of the driving transistor T1 and the potential of one end of the feedback transistor T8 and the feedback capacitor C1 connected in series through the first initialization transistor T4, and the second initialization line can initialize the anode potential of the light-emitting device D1 and the potential of the other end of the feedback transistor T8 and the feedback capacitor C1 connected in series through the second initialization transistor T7, which can not only improve the accuracy of the light-emitting current flowing through the driving transistor T1 and / or the light-emitting device D1; it can also adjust the voltage difference between one end of the feedback transistor T8 and the feedback capacitor C1 connected in series and the other end of the feedback transistor T8 and the feedback capacitor C1 connected in series, so as to accurately control the voltage value of the linkage change between the gate of the driving transistor T1 and the anode of the light-emitting device D1, and obtain the expected gate potential of the driving transistor T1 and / or the anode potential of the light-emitting device D1.

[0050] Moreover, by sharing the same second control line for the gates of the first initialization transistor T4 and the second initialization transistor T7, the number of wirings required for the pixel circuit can be saved, which is beneficial to increasing the density of the pixel circuit or the aperture ratio of the display panel.

[0051] In one embodiment, the pixel circuit further includes a first light-emitting control transistor T6, a second light-emitting control transistor T5, a writing transistor T2, and a compensation transistor T3. One of the source or drain of the first light-emitting control transistor T6 is electrically connected to the other of the source or drain of the driving transistor T1. The other of the source or drain of the first light-emitting control transistor T6 is electrically connected to the anode of the light-emitting device D1. The gate of the first light-emitting control transistor T6 is electrically connected to the light-emitting control line. One of the source or drain of the second light-emitting control transistor T5 is electrically connected to the first power line. The other of the source or drain of the second light-emitting control transistor T5 is electrically connected to one of the source or drain of the driving transistor T1. The gate of the second light-emitting control transistor T5 is electrically connected to the light-emitting control line. One of the source or drain of the writing transistor T2 is electrically connected to the data line. The other of the source or drain of the writing transistor T2 is electrically connected to one of the source or drain of the driving transistor T1. The gate of the writing transistor T2 is electrically connected to the third control line. One of the source or drain of the compensation transistor T3 is electrically connected to the other of the source or drain of the driving transistor T1. The other of the source or drain of the compensation transistor T3 is electrically connected to the gate of the driving transistor T1. The gate of the compensation transistor T3 is electrically connected to the fourth control line.

[0052] It should be noted that by sharing the same light-emitting control line for the gates of the second light-emitting control transistor T5 and the first light-emitting control transistor T6, the number of wirings required for the pixel circuit can be saved, which is beneficial to increasing the density of the pixel circuit or the aperture ratio of the display panel.

[0053] Moreover, under the control of the third control line and the fourth control line, the data signal Data transmitted in the data line can sequentially pass through the writing transistor T2, the driving transistor T1, and the compensation transistor T3 to the gate of the driving transistor T1. At the same time, the data signal Data can also pre-charge the anode of the light-emitting device D1 through the feedback transistor T8 and the feedback capacitor C1 to raise the anode potential of the light-emitting device D1 in advance, which can reduce the time for raising the anode potential of the light-emitting device D1 to its turn-on voltage during the light-emitting stage, so that the light-emitting device D1 starts to emit light earlier during the light-emitting stage, which increases the effective light-emitting time of the light-emitting device D1.

[0054] In one embodiment, the pixel circuit further includes a storage capacitor Cst. One end of the storage capacitor Cst is electrically connected to the gate of the driving transistor T1, and the other end of the storage capacitor Cst is electrically connected to the first power supply line.

[0055] In one embodiment, the pixel circuit further includes a bootstrap capacitor Cboost. One end of the bootstrap capacitor Cboost is electrically connected to the gate of the writing transistor T2, and the other end of the bootstrap capacitor Cboost is electrically connected to the gate of the driving transistor T1.

[0056] In one embodiment, at least one of the driving transistor T1, the first light-emitting control transistor T6, the second light-emitting control transistor T5, the first initialization transistor T4, the second initialization transistor T7, the writing transistor T2, the feedback transistor T8, and the compensation transistor T3 may be, but is not limited to, an N-channel thin-film transistor. Specifically, it may also be a metal-oxide thin-film transistor, for example, an indium gallium zinc oxide thin-film transistor. Alternatively, at least one of the driving transistor T1, the first light-emitting control transistor T6, the second light-emitting control transistor T5, the first initialization transistor T4, the second initialization transistor T7, the writing transistor T2, and the compensation transistor T3 may also be a P-channel thin-film transistor. Specifically, it may also be a polysilicon thin-film transistor, for example, a low-temperature polysilicon thin-film transistor.

[0057] Preferably, the driving transistor T1, the first light-emitting control transistor T6, the second light-emitting control transistor T5, the feedback transistor T8, and the writing transistor T2 are all P-channel low-temperature polysilicon thin-film transistors to maximize the dynamic performance of the pixel circuit; the first initialization transistor T4, the compensation transistor T3, and the second initialization transistor T7 are all N-channel indium gallium zinc oxide thin-film transistors to reduce the leakage current phenomenon at the gate of the driving transistor T1 and the anode of the light-emitting device D1.

[0058] Preferably, the feedback transistor T8 may also be an N-channel indium gallium zinc oxide thin-film transistor to further reduce the leakage current phenomenon at the gate of the driving transistor T1.

[0059] It should be noted that the first power supply line is used to transmit the first power supply signal VDD, the second power supply line is used to transmit the second power supply signal VSS, and the potential of the first power supply signal VDD is higher than that of the second power supply signal VSS. The light emission control line is used to transmit the light emission control signal EM. The first control line is used to transmit the first control signal, and the first control signal can be, but is not limited to, the scan signal Pscan2, or other scan signals with positive pulses. The second control line is used to transmit the second control signal, and the second control signal can be, but is not limited to, the scan signal Nscan[n - 5], or the scan signals Nscan[n - 1], Nscan[n - 2], Nscan[n - 3], Nscan[n - 4], Nscan[n - 6]... and so on. The third control line is used to transmit the third control signal, and the third control signal can be, but is not limited to, the scan signal Pscan1, or other control signals used. The fourth control line is used to transmit the fourth control signal, and the fourth control signal can be, but is not limited to, the scan signal Nscan[n], or other applicable control signals. The first initialization line is used to transmit the first initialization signal Vi_G. The second initialization line is used to transmit the second initialization line. The data line is used to transmit the data signal Data.

[0060] The working process of the above pixel circuit in one frame can include the following stages:

[0061] The first stage (initialization stage) S1: As Figure 5 , Figure 6 shown, the light emission control signal EM, the scan signal Nscan[n - 5], and the scan signal Pscan1 are set high, the scan signals Nscan[n] and Pscan2 are set low, and the first initialization transistor T4, the second initialization transistor T7, and the feedback transistor T8 are in the conducting state. Among them, the feedback transistor T8 is in the conducting state for at least part of the time in the first stage. In this way, the potential of one end of the series-connected feedback transistor T8 and the feedback capacitor C1, and the potential of the other end of the series-connected feedback transistor T8 and the feedback capacitor C1 can be initialized to the potential of the first initialization signal Vi_G and the potential of the second initialization signal Vi_Ano respectively.

[0062] The second stage (data writing stage) S2: As Figure 5 , Figure 7As shown, the emission control signal EM and the scan signal Nscan[n] are set high, the scan signals Pscan1, Nscan[n - 5], and Pscan2 are set low, the first initialization transistor T4, the second initialization transistor T7, the first emission control transistor T6, and the second emission control transistor T5 are all in the cut-off state, the compensation transistor T3 is in the conducting state, and the write transistor T2 and the feedback transistor T8 are synchronously in the conducting state for at least part of the time in the second stage S2.

[0063] It should be noted that in this stage, the data signal Data is written to the gate of the driving transistor T1 through the write transistor T2, the driving transistor T1, and the compensation transistor T3 in sequence, and the anode potential of the light-emitting device D1 is raised by the series-connected feedback transistor T8 and the feedback capacitor C1, and the anode potential of the light-emitting device D1 is less than or equal to the turn-on voltage of the light-emitting device D1.

[0064] It can be understood that when the anode potential of the light-emitting device D1 is equal to the turn-on voltage of the light-emitting device D1, the light-emitting device D1 does not emit light because the first emission control transistor T6 or the second emission control transistor T5 is in the cut-off state. In this stage, the gate potential of the driving transistor T1 rises from ViG to K*(VData + Vth), and correspondingly, the anode potential of the light-emitting device D1 rises from ViAno to K*(VData + Vth) - ViG + ViAno.

[0065] Wherein, ViG is the potential of the first initialization signal Vi_G. VData is the potential of the data signal Data. Vth is the threshold voltage of the driving transistor T1. K is related to the pixel circuit and is a constant. ViAno is the potential of the second initialization signal Vi_Ano.

[0066] The third stage (emission stage) S3: As Figure 5 、 Figure 8 shown, the scan signals Pscan1 and Pscan2 are set high, the emission control signal EM, the scan signal Nscan[n], and the scan signal Nscan[n - 5] are set low, the first initialization transistor T4, the second initialization transistor T7, the compensation transistor T3, the write transistor T2, and the feedback transistor T8 are all in the cut-off state, the driving transistor T1, the first emission control transistor T6, and the second emission control transistor T5 are in the conducting state, and the light-emitting device D1 starts to emit light.

[0067] The third sub-stage S3+: As Figure 5 、 Figure 9 and Figure 10As shown, the scan signal Pscan1 is set high, and the scan signals Pscan2, EM (emission control signal), Nscan[n], and Nscan[n - 5] are set low. The first initialization transistor T4, the second initialization transistor T7, the compensation transistor T3, and the write transistor T2 are all in the cut-off state, while the feedback transistor T8, the driving transistor T1, the first emission control transistor T6, and the second emission control transistor T5 are in the conducting state.

[0068] It should be noted that due to the leakage current of the compensation transistor T3, the potential at the gate of the driving transistor T1, i.e., point Q, will slightly decrease, causing the potential at the anode of the light-emitting device D1, i.e., point C, to rise, increasing the light-emitting current flowing through the light-emitting device D1 and thus increasing the brightness of the light-emitting device D1. When the frequency of the first control signal is greater than the frequency of the emission control signal EM, i.e., the frequency of the scan signal Pscan2 is higher than the frequency of the emission control signal EM, the rise in the potential at point C can be fed back to point Q through the series-connected feedback transistor T8 and feedback capacitor C1, offsetting the influence of the leakage current on the potential at point Q and reducing the brightness of the light-emitting device D1, thereby maintaining the brightness of the light-emitting device D1. That is to say, the potential at the gate of the driving transistor T1 changes in the opposite direction to the potential at the anode of the light-emitting device D1 through the series-connected feedback transistor T8 and feedback capacitor C1. Specifically, Figure 10 The explanation is as follows:

[0069] Among them, VQ represents the potential at point Q, and VC represents the potential at point C. VQ1 represents the potential change curve of point Q in the third sub-stage S3+ when the frequency of the scan signal Pscan2 is equal to the frequency of the emission control signal EM. VC1 represents the potential change curve of point C in the third sub-stage S3+ when the frequency of the scan signal Pscan2 is equal to the frequency of the emission control signal EM. VQ2 represents the potential change curve of point Q in the third sub-stage S3+ when the frequency of the scan signal Pscan2 is greater than the frequency of the emission control signal EM. VC2 represents the potential change curve of point C in the third sub-stage S3+ when the frequency of the scan signal Pscan2 is greater than the frequency of the emission control signal EM.

[0070] Through analysis, it can be found that when the frequency of the scan signal Pscan2 is equal to the frequency of the emission control signal EM, VQ1 continuously decreases and VC1 continuously increases, which will cause the light-emitting current flowing through the light-emitting device D1 to continuously increase or decrease in magnitude, resulting in unstable light-emitting brightness of the light-emitting device D1.

[0071] When the frequency of the scanning signal Pscan2 is greater than the frequency of the emission control signal EM, or when the scanning signal Pscan2 is configured to have at least one negative pulse during the emission stage, each time the feedback transistor T8 conducts, the change trends of VQ2 and VC2 both change, such that one of VQ2 or VC2 increases while the other decreases, thereby stably controlling the emission current flowing through the driving transistor T1.

[0072] Fourth stage S4 (black insertion stage): As Figure 5 , Figure 11 shown, the emission control signal EM and the scanning signal Pscan1 are set high, the scanning signal Pscan2, the scanning signal Nscan[n], and the scanning signal Nscan[n - 5] are set low, the first initialization transistor T4, the second initialization transistor T7, the compensation transistor T3, the writing transistor T2, the first emission control transistor T6, and the second emission control transistor T5 are all in the cut-off state, and the feedback transistor T8 and the driving transistor T1 are in the conducting state.

[0073] It should be noted that when the feedback transistor T8 conducts, the potential at point C is coupled to point Q through the feedback capacitor C1, raising the potential at point Q, which in turn acts on point C in the reverse direction and reduces the potential at point C, causing the emission current flowing through the light-emitting device D1 to decrease, which can offset part of the influence caused by the leakage of the compensation transistor T3. That is to say, in this stage after the emission stage, the gate potential of the driving transistor T1 can be raised and the anode potential of the light-emitting device D1 can be reduced through the series-connected feedback transistor T8 and feedback capacitor C1.

[0074] Among them, since the frame time under high-frequency driving (high refresh rate) is shorter than the frame time under low-frequency driving (low refresh rate), the number of pulses of the scanning signal Pscan1 in the frame time of high-frequency driving is less than the number of pulses of the scanning signal Pscan1 in the frame time of low-frequency driving. This will cause the data signal Data that does not reach the gate of the driving transistor T1 under low-frequency driving to affect the source potential and drain potential of the driving transistor T1. Therefore, by realizing the mutual feedback of the gate potential of the driving transistor T1 and the anode potential of the light-emitting device D1 through the feedback transistor T8 and the feedback capacitor C1 under low-frequency driving, the emission brightness of the light-emitting device D1 can be better stabilized.

[0075] In one embodiment, this embodiment provides a display panel, which includes a plurality of pixel circuits in at least one of the above embodiments.

[0076] It can be understood that the display panel provided in this embodiment can control the gate potential of the driving transistor T1 and the anode potential of the light-emitting device D1 to change in linkage by coupling the feedback transistor T8 and the feedback capacitor C1 in series between the gate of the driving transistor T1 and the anode of the light-emitting device D1. Not only can the light-emitting current flowing through the light-emitting device D1 be more stably controlled through the gate potential of the driving transistor T1 and the anode potential of the light-emitting device D1 after the linkage change, thereby reducing the brightness change of the light-emitting device D1; it can also control the anode potential of the light-emitting device D1 to reach the start-up voltage earlier, thereby increasing the effective light-emitting time or improving the light-emitting brightness of the light-emitting device D1.

[0077] Furthermore, since the light emitting currents flowing through the light emitting devices D1 in different pixel circuits are closer to unity, the light emitting brightness of different light emitting devices D1 is more uniform, which can improve the color cast of the display panel, for example, green cast.

[0078] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0079] The pixel circuit and display panel provided in the embodiments of the present application are introduced in detail above. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the technical solutions and core ideas of the present application. Ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein with equivalents. These modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A pixel circuit, characterized in that, The pixel circuit includes: A driving transistor, one of the source or drain of the driving transistor is electrically connected to a first power supply line; A light-emitting device, the anode of the light-emitting device is electrically connected to the other of the source or drain of the driving transistor, and the cathode of the light-emitting device is electrically connected to a second power supply line; A feedback transistor, the gate of the feedback transistor is electrically connected to a first control line; and A feedback capacitor, the feedback capacitor and the feedback transistor are connected in series between the gate of the driving transistor and the anode of the light-emitting device; A first initialization transistor, the first initialization transistor is connected in series between one end of the feedback capacitor and a first initialization line, and the gate of the first initialization transistor is electrically connected to a second control line; Wherein, the feedback transistor conducts at least once during the light-emitting stage of the pixel circuit.

2. The pixel circuit according to claim 1, wherein One end of the feedback capacitor is electrically connected to the first initialization line through the first initialization transistor, and the first initialization line receives a first initialization signal; the other end of the feedback capacitor is electrically connected to a second initialization line, and the second initialization line receives a second initialization signal; the feedback transistor is connected in series between the feedback capacitor and the first initialization line or the second initialization line; the potential of the first initialization signal is different from the potential of the second initialization signal.

3. The pixel circuit according to claim 2, wherein The pixel circuit further includes a second initialization transistor, the second initialization transistor is connected in series between the other end of the feedback capacitor and the second initialization line, and the gate of the second initialization transistor is electrically connected to the second control line.

4. The pixel circuit according to claim 3, wherein The pixel circuit further includes: A first light-emitting control transistor, one of the source or drain of the first light-emitting control transistor is electrically connected to the other of the source or drain of the driving transistor, the other of the source or drain of the first light-emitting control transistor is electrically connected to the anode of the light-emitting device, and the gate of the first light-emitting control transistor is electrically connected to a light-emitting control line; A second light-emitting control transistor, one of the source or drain of the second light-emitting control transistor is electrically connected to the first power supply line, the other of the source or drain of the second light-emitting control transistor is electrically connected to one of the source or drain of the driving transistor, and the gate of the second light-emitting control transistor is electrically connected to the light-emitting control line; A writing transistor, one of the source or drain of the writing transistor is electrically connected to a data line, the other of the source or drain of the writing transistor is electrically connected to one of the source or drain of the driving transistor, and the gate of the writing transistor is electrically connected to a third control line; and A compensation transistor, one of the source or drain of the compensation transistor is electrically connected to the other of the source or drain of the driving transistor, the other of the source or drain of the compensation transistor is electrically connected to the gate of the driving transistor, and the gate of the compensation transistor is electrically connected to a fourth control line.

5. The pixel circuit according to claim 3, characterized in that, In the initialization stage of the pixel circuit, the first initialization transistor and the second initialization transistor are both in the conducting state, and the feedback transistor is in the conducting state for at least part of the initialization stage to reset the gate potential of the driving transistor and one end potential of the feedback capacitor through the first initialization signal, and to reset the anode potential of the light-emitting device and the other end potential of the feedback capacitor through the second initialization signal.

6. The pixel circuit according to claim 1, wherein In the data writing stage of the pixel circuit, the data signal raises the anode potential of the light-emitting device through the series-connected feedback transistor and feedback capacitor, and the anode potential of the light-emitting device is less than the turn-on voltage of the light-emitting device.

7. The pixel circuit according to claim 1, wherein In the light-emitting stage of the pixel circuit, the gate potential of the driving transistor changes in the opposite direction to the anode potential of the light-emitting device through the series-connected feedback transistor and feedback capacitor.

8. The pixel circuit according to claim 1, wherein In the blanking stage of the pixel circuit, the gate potential of the driving transistor is raised and the anode potential of the light-emitting device is lowered through the series-connected feedback transistor and feedback capacitor.

9. The pixel circuit according to claim 4, wherein The first control line is used to transmit a first control signal, and the light-emitting control line is used to transmit a light-emitting control signal; the frequency of the first control signal is greater than the frequency of the light-emitting control signal.

10. A display panel, characterized in that, It includes a plurality of pixel circuits as described in any one of claims 1 to 9. Each pixel circuit further includes a storage capacitor. One end of the storage capacitor is electrically connected to the gate of the driving transistor, and the other end of the storage capacitor is electrically connected to the first power supply line.

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