Pixel circuit and display panel

Abstract

The present application discloses a pixel circuit and a display panel, wherein the pixel circuit includes a first light-emitting control transistor, a first initialization transistor, a first transistor, a light-emitting device and a first capacitor. The first transistor and the first capacitor are coupled between the first light-emitting control transistor and the light-emitting device, so that the reset current flowing through the first initialization transistor is independent of the capacitance of the light-emitting device itself but is related to the first capacitor. Since the change of the capacitance of the first capacitor over time is almost negligible, the reset current can remain unchanged, that is, it will not change with the change of the capacitance of the light-emitting device itself. The reset current is a part of the light-emitting current flowing through the first light-emitting control transistor. Therefore, when the reset current and the light-emitting current flowing through the first light-emitting control transistor remain unchanged, the light-emitting current flowing through the light-emitting device, which is another part of the light-emitting current flowing through the first light-emitting control transistor, can be kept constant.

Description

Technical Field

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

[0002] In the pixel circuit, the stability of the characteristics of the light-emitting device is one of the key factors affecting the display quality. As the pixel circuit or display panel works for a longer time or in a high temperature and high humidity environment, the characteristics of the light-emitting device will change, which usually causes the brightness of the light-emitting device to change. Summary of the invention

[0003] The present application provides a pixel circuit and a display panel to alleviate the technical problem that the brightness of a light-emitting device changes with changes in its own characteristics.

[0004] In a first aspect, the present application provides a pixel circuit, which includes a first power line, a second power line, a driving transistor connected in series between the first power line and the second power line, a first light-emitting control transistor and a light-emitting device, a first node, a first initialization line, a first capacitor and a first transistor, wherein the first node is located between the first light-emitting control transistor and the light-emitting device; the first initialization line is electrically connected to the first node through a first initialization transistor; the first capacitor is connected between the first node and a potential transmission line; and the first transistor is connected between the first node and the light-emitting device.

[0005] In some embodiments, a gate of the first light emission control transistor is connected to a light emission control line, a gate of the first initialization transistor is connected to a first control line, and a gate of the first transistor is connected to a second control line.

[0006] In some of the embodiments, the potential transmission line is used to transmit a constant voltage signal.

[0007] In some embodiments, the potential transmission line is one of a first power line, a first initialization line, or a second power line.

[0008] In some embodiments, a channel type of the first light emission control transistor is the same as a channel type of the first transistor, and the second control line is a light emission control line.

[0009] In some embodiments, the pixel circuit also includes a driving transistor and a second initialization transistor, one of the source or drain of the driving transistor is connected to one of the source or drain of the first light-emitting control transistor, and the other of the source or drain of the driving transistor is electrically connected to the first power line; one of the source or drain of the second initialization transistor is connected to the gate of the driving transistor, the other of the source or drain of the second initialization transistor is connected to the second initialization line, and the gate of the second initialization transistor is connected to the third control line; wherein the potential transmission line is the first power line or the second initialization line.

[0010] In some embodiments, the pixel circuit also includes a second light-emitting control transistor, one of the source or drain of the second light-emitting control transistor is connected to the other of the source or drain of the driving transistor, the other of the source or drain of the second light-emitting control transistor is connected to the first power line, and the gate of the second light-emitting control transistor is connected to the light-emitting control line or the second control line.

[0011] In some embodiments, in the writing phase of the pixel circuit, the first initialization line receives a first initialization signal, the first light emitting control transistor and the first transistor are both in a cut-off state, and the first initialization signal is transmitted to the first capacitor through the first initialization transistor.

[0012] In some embodiments, in the light emitting stage of the pixel circuit, the first light emitting control transistor, the second light emitting control transistor, the driving transistor and the first transistor are turned on, and the charge in the self-capacitance of the light emitting device flows to the first capacitor through the first transistor.

[0013] In a second aspect, the present application provides a display panel, which includes a plurality of pixel circuits in the above-mentioned embodiments.

[0014] In some of the embodiments, in the same display panel, the capacitances of the first capacitors in different pixel circuits are fixed and equal.

[0015] The pixel circuit and display panel provided by the present application couple the first transistor and the first capacitor between the first light-emitting control transistor and the light-emitting device, so that the reset current flowing through the first initialization transistor is independent of the self-capacitance of the light-emitting device but is related to the first capacitor. Since the change of the capacitance of the first capacitor over time is almost negligible, the reset current can remain unchanged, that is, it will not change with the change of the self-capacitance of the light-emitting device. The reset current is a part of the light-emitting current flowing through the first light-emitting control transistor. Therefore, when the reset current and the light-emitting current flowing through the first light-emitting control transistor remain unchanged, the light-emitting current flowing through the light-emitting device as the other part of the light-emitting current flowing through the first light-emitting control transistor can be kept constant, thereby reducing or avoiding the influence of the change of the self-capacitance of the light-emitting device on its light-emitting brightness. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] 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.

[0017] Figure 1 It is a structural schematic diagram of a pixel circuit in the related art.

[0018] Figure 2 Schematic diagram of the color difference comparison of low grayscale white screen before and after high temperature and high humidity.

[0019] Figure 3 Schematic diagram of the capacitance change of light-emitting devices of different colors after high temperature and high humidity.

[0020] Figure 4 A schematic diagram of the structure of a pixel circuit provided in an embodiment of the present application.

[0021] Figure 5 for Figure 1 , Figure 4 Timing diagram of the pixel circuit shown.

[0022] Figure 6 for Figure 4 The pixel circuit shown in Figure 5 Schematic diagram of the status in the T1 period.

[0023] Figure 7 for Figure 4 The pixel circuit shown in Figure 5 Schematic diagram of the state in the T2 period.

[0024] Figure 8 for Figure 4 The pixel circuit shown in Figure 5 Schematic diagram of the state in the T3 period. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0026] Figure 1 It is a structural schematic diagram of a pixel circuit in the related technology, which includes a driving transistor T1, a first light-emitting control transistor T6, a second light-emitting control transistor T5, a first initialization transistor T7, a second initialization transistor T4, a write transistor T2, a compensation transistor T3, a light-emitting device D1 and a second capacitor Cst.

[0027] The first power line is connected to one end of the second capacitor Cst and one of the source or drain of the second light emitting control transistor T5, the other of the source or drain of the second light emitting control transistor T5 is connected to one of the source or drain of the driving transistor T1, the other of the source or drain of the driving transistor T1 is connected to one of the source or drain of the first light emitting control transistor T6, the other of the source or drain of the first light emitting control transistor T6 is connected to the anode of the light emitting device D1, the cathode of the light emitting device D1 is connected to the second power line, the gate of the first light emitting control transistor T6 is connected to the gate of the second light emitting control transistor T5 and the light emitting control line, and the other end of the second capacitor Cst is connected to the gate of the driving transistor T1.

[0028] One of the source or drain of the first initialization transistor T7 is connected to the anode of the light emitting device D1 , the other of the source or drain of the first initialization transistor T7 is connected to the first initialization line, and the gate of the first initialization transistor T7 is connected to the first control line.

[0029] One of the source or drain of the second initialization transistor T4 is connected to the gate of the driving transistor T1 , the other of the source or drain of the second initialization transistor T4 is connected to the second initialization line, and the gate of the second initialization transistor T4 is connected to the third control line.

[0030] One of the source or drain of the write transistor T2 is connected to one of the source or drain of the drive transistor T1 , the other of the source or drain of the write transistor T2 is connected to the data line, and the gate of the write transistor T2 is connected to the first control line.

[0031] One of the source or drain of the compensation transistor T3 is 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 connected to the gate of the driving transistor T1 , and the gate of the compensation transistor T3 is connected to the first control line.

[0032] It should be noted that the first power line is used to transmit a first power signal ELVDD, the second power line is used to transmit a second power signal ELVSS, and the potential of the first power signal ELVDD is higher than the potential of the second power signal ELVSS. The light-emitting control line is used to transmit a light-emitting control signal EM. The first control line is used to transmit a first control signal, such as a scan signal Pscan(n). The data line is used to transmit a data signal Data. The third control line is used to transmit a third control signal, such as a scan signal Pscan(n-1). The first initialization line is used to transmit a first initialization signal VI2. The second initialization line is used to transmit a second initialization signal VI1.

[0033] Among them, when the channel material of the compensation transistor T3 is low-temperature polysilicon, in order to improve the dynamic performance while reducing the gate leakage current of the driving transistor T1, the compensation transistor T3 can be a dual-gate transistor or coupled by two transistors. Similarly, when the channel material of the second initialization transistor T4 is low-temperature polysilicon, in order to improve the dynamic performance while reducing the gate leakage current of the driving transistor T1, the second initialization transistor T4 can also be a dual-gate transistor or coupled by two transistors. For example, the coupling of two transistors can be such that the gates of the two transistors are connected together, the source of one transistor is connected to the drain of the other transistor, the drain of the one transistor serves as the drain of the compensation transistor T3 or the second initialization transistor T4, and the source of the other transistor serves as the source of the compensation transistor T3 or the second initialization transistor T4.

[0034] It should be noted that the stability of the characteristics of the above-mentioned light-emitting device D1 is one of the key factors affecting the display quality. The inventor of the present application found through reliability test analysis of the display panel that when the display panel or pixel circuit has been working for a long time, or has been working for a short period of time in a high temperature and high humidity environment, the characteristics of the light-emitting device D1 will change. After further research by the inventor of the present application, it was found that the reason for the change in brightness of a certain pixel circuit or the entire display panel is that one of the characteristics of the light-emitting device D1 has changed, and one of the characteristics of the light-emitting device D1 is the self-capacitance C of the light-emitting device D1. EL .

[0035] Figure 2 This is a schematic diagram comparing the color differences of low grayscale white images before and after high temperature and high humidity. Figure 2The middle left picture is a low grayscale white image before high temperature and high humidity. Figure 2 The middle right picture is a low grayscale white picture after high temperature and high humidity. After comparison, it is found that Figure 2 Middle right picture Figure 2 The display color of the middle left picture is more green. After a deeper and more extensive comparison and analysis by the inventors, it was found that this is because the display panel includes multiple pixel circuits, some of the light-emitting devices D1 in the multiple pixel circuits are red light-emitting devices D1, some of the light-emitting devices D1 in the multiple pixel circuits are green light-emitting devices D1, and some of the light-emitting devices D1 in the multiple pixel circuits are blue light-emitting devices D1. After long-term operation or high temperature and high humidity testing, the self-capacitance C of the light-emitting devices D1 of different colors EL The amount of change is also different, which leads to differences in the brightness of the light-emitting devices D1 of different colors, which in turn leads to Figure 2 The middle right image should show Figure 2 The low grayscale white image in the middle left picture, however Figure 2 The middle-right picture, however, shows a greenish tint, which is also a type of color cast.

[0036] For example Figure 3 As shown in the figure, after the different color light emitting devices D1 have been tested at high temperature and high humidity (temperature 60°C, humidity 90%) for 240 hours, the self capacitance C of the red light emitting device D1 (R) is EL The self-capacitance C of the green light-emitting device D1(G) has increased by 22.7%. EL The self-capacitance C of the blue light-emitting device D1 (B) is reduced by 24.1%. EL It has decreased by 8%. Where △C represents the self-capacitance C of the corresponding light emitting device D1 EL The change in capacitance C of the corresponding light-emitting device D1 before long-term operation or high temperature and high humidity test EL That is the initial capacitance.

[0037] It is understandable that the above-mentioned light emitting device D1, 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 C EL , the difference is just whether it is big or small.

[0038] The following description takes the light emitting device D1 as an organic light emitting diode as an example. The organic light emitting diode is a light emitting device D1 composed of an anode, a cathode and a functional layer and / or a light emitting layer therebetween. In addition to the rectifying characteristics of a diode, it also has a capacitance effect. Figure 1 The equivalent pixel circuit shown in FIG. 1 is operated in consideration of the capacitance of the light emitting device D1. Figure 5 As shown:

[0039] In the T3' period, the light emitting control signal EM is set low, the first light emitting control transistor T6 and the second light emitting control transistor T5 are turned on or turned on, and the first power supply signal ELVDD is controlled by the driving transistor T1 to drive the light emitting device D1 to emit light. At this time, the potential at point C (V C ) and the anode potential of the light-emitting device D1 (V EL ) is the same, that is, V C =V EL +V SS , where V SS is the cathode potential of the light emitting device D1.

[0040] In the T1 period, the scan signal Pscan(n-1) is set low, and the second initialization signal VI1 resets the lower plate of the second capacitor Cst, ie, the Q point.

[0041] In the T2 period, the data signal Data is sequentially written into the lower plate of the second capacitor Cst through the write transistor T2, the drive transistor T1, and the compensation transistor T3; at the same time, the first initialization signal VI2 resets the point C (i.e., the anode of the light-emitting device D1). At this time, the residual charge of the light-emitting device D1 in the previous frame is discharged to the first initialization line through the first initialization transistor T7, thus completing the reset of the light-emitting device D1. At this time, the current I flowing through the first initialization transistor T7 is VI2 It can be roughly estimated as:

[0042] I VI2 =2π*f*C EL *(V C -V VI2 )=2π*f*C EL *(V EL +V SS -V VI2 ) (1)

[0043] Wherein, f is the frequency of the scanning signal Pscan(n-1). VI2 is the potential of the first initialization signal VI2. EL is the self-capacitance C of the light-emitting device D1 EL . V C is the potential at point C. V EL is the anode potential of the light emitting device D1.

[0044] In the T3 period, the light emitting control signal EM is set low, and the light emitting device D1 starts to emit light. In this stage, the current flowing through point B into point C is I BC , the current (i.e., the light-emitting current) flowing into the second power line through the light-emitting device D1 is I VSS I BC ,I VSS and IVI2 The three satisfy the following relationship:

[0045] I BC =I VSS +I VI2 (2)

[0046] The above formula 2 shows that the current I controlled by the driving transistor T1 is BC , part (I VSS ) is used for the light emitting device D1 to emit light, and the other part (I VI2 ) is consumed by the anode reset circuit of the light emitting device D1. According to the above formulas 1 and 2, it can be known that due to the self-capacitance C of the light emitting device D1 EL Changes in I VI2 will change accordingly. BC Under the condition of no change, it leads to I VSS The brightness of the light emitting device D1 will change with the use of the light emitting device D1, which will lead to instability of the brightness of the light emitting device D1. That is, the brightness of the light emitting device D1 will change with the change of its own characteristics.

[0047] In view of the technical problem mentioned above that the brightness of the light emitting device D1 changes with the change of its own characteristics, this embodiment provides a pixel circuit, see Figures 4 to 8 ,like Figure 4 As shown, the pixel circuit includes a first power line VDD, a second power line VSS, a driving transistor T1, a first light-emitting control transistor T6 and a light-emitting device D1, a first node, a first initialization line, a second capacitor C2 and a first transistor T8, wherein the first node is located between the first light-emitting control transistor T6 and the light-emitting device D1; the first initialization line is electrically connected to the first node through a first initialization transistor T7; the second capacitor C2 is connected between the first node and a potential transmission line; and the first transistor T8 is connected between the first node and the light-emitting device D1.

[0048] It should be noted that the gate of the first light emitting control transistor T6 is connected to the light emitting control line, the gate of the first initialization transistor T7 is connected to the first control line, and the gate of the first transistor T8 is connected to the second control line.

[0049] In one embodiment, the pixel circuit includes a first light-emitting control transistor T6, a first initialization transistor T7, a first transistor T8, a light-emitting device D1 and a first capacitor C2, one of the source or drain of the first light-emitting control transistor T6 is electrically connected to the first power line, and the gate of the first light-emitting control transistor T6 is connected to the light-emitting control line; one of the source or drain of the first initialization transistor T7 is connected to the other of the source or drain of the first light-emitting control transistor T6, the other of the source or drain of the first initialization transistor T7 is connected to the first initialization line, and the gate of the first initialization transistor T7 is connected to the first control line; one of the source or drain of the first transistor T8 is connected to one of the source or drain of the first initialization transistor T7, and the gate of the first transistor T8 is connected to the second control line; the anode of the light-emitting device D1 is connected to the other of the source or drain of the first transistor T8, and the cathode of the light-emitting device D1 is connected to the second power line; one end of the first capacitor C2 is connected to one of the source or drain of the first transistor T8, and the other end of the first capacitor C2 is connected to the potential transmission line.

[0050] It can be understood that the pixel circuits provided in the above two embodiments couple the first transistor T8 and the first capacitor C2 between the first light emitting control transistor T6 and the light emitting device D1, so that the reset current flowing through the first initialization transistor T7 and the self-capacitor C EL The reset current is not related to the first capacitor C2, because the change of the capacitance of the first capacitor C2 over time is almost negligible, which makes the reset current remain unchanged, that is, it will not change with the capacitance C of the light emitting device D1. EL The reset current is a part of the light-emitting current flowing through the first light-emitting control transistor T6. Therefore, when the reset current and the light-emitting current flowing through the first light-emitting control transistor T6 remain unchanged, the light-emitting current flowing through the light-emitting device D1, which is another part of the light-emitting current flowing through the first light-emitting control transistor T6, can be kept constant, thereby reducing or avoiding the self-capacitance C of the light-emitting device D1. EL The effect of changes in its luminous brightness.

[0051] In one embodiment, the potential transmission line is used to transmit a constant voltage signal.

[0052] It should be noted that, since the capacitance of the first capacitor C2 is fixed after being configured in the pixel circuit, the constant voltage signal transmitted by the potential transmission line can ensure that the potential at point C is relatively stable. The capacitance of the first capacitor C2 can be greater than or equal to the capacitance C of the light emitting device D1. EL, the first transistor T8 can absorb the anode charge of the light-emitting device D1 in the on state during the light-emitting stage, or transfer the self-capacitance C of the light-emitting device D1 during the light-emitting stage. EL The charge in the capacitor C2 is transferred to the first capacitor C2 to complete the anode resetting of the light emitting device D1.

[0053] In one embodiment, the potential transmission line is one of a first power line, a first initialization line, or a second power line.

[0054] It should be noted that when the potential transmission line is any one of the first power line, the first initialization line or the second power line, the potential transmission line can be shared with any one of the first power line, the first initialization line or the second power line, which can save a dedicated potential transmission line, which is beneficial to saving the space occupied by the pixel circuit and improving the density of the pixel circuit or the aperture ratio of the display panel. Alternatively, the potential transmission line can also be an independent routing line, which can also improve the control flexibility of the first transistor T8.

[0055] In one embodiment, the channel type of the first light emission control transistor T6 is the same as the channel type of the first transistor T8, and the second control line is a light emission control line.

[0056] It should be noted that, when the channel type of the first light-emitting control transistor T6 is the same as the channel type of the first transistor T8, the gate of the first light-emitting control transistor T6 and the gate of the first transistor T8 can share the same light-emitting control line, which can also save a dedicated potential transmission line, which is beneficial to saving the space occupied by the pixel circuit and improving the density of the pixel circuit or the aperture ratio of the display panel.

[0057] In one of the embodiments, the pixel circuit further includes a driving transistor T1 and a second initialization transistor T4, one of the source or drain of the driving transistor T1 is connected to one of the source or drain of the first light-emitting control transistor T6, and the other of the source or drain of the driving transistor T1 is electrically connected to the first power line; one of the source or drain of the second initialization transistor T4 is connected to the gate of the driving transistor T1, the other of the source or drain of the second initialization transistor T4 is connected to the second initialization line, and the gate of the second initialization transistor T4 is connected to the third control line; wherein the potential transmission line is the first power line or the second initialization line.

[0058] It should be noted that, when the potential transmission line is the first power line or the second initialization line, the first power line can be reused as the potential transmission line, which can also save a dedicated potential transmission line, which is beneficial to saving the space occupied by the pixel circuit and improving the density of the pixel circuit or the aperture ratio of the display panel; or, the gate of the first transistor T8 and the gate of the second initialization transistor T4 can share the same second initialization line, which can also save a dedicated potential transmission line, which is beneficial to saving the space occupied by the pixel circuit and improving the density of the pixel circuit or the aperture ratio of the display panel.

[0059] In one embodiment, the pixel circuit also includes a second light emitting control transistor T5, one of the source or the drain of the second light emitting control transistor T5 is connected to the other of the source or the drain of the driving transistor T1, the other of the source or the drain of the second light emitting control transistor T5 is connected to the first power line, and the gate of the second light emitting control transistor T5 is connected to the light emitting control line or the second control line.

[0060] It should be noted that when the gate of the second light-emitting control transistor T5 is connected to the light-emitting control line, the gate of the first light-emitting control transistor T6, the gate of the second light-emitting control transistor T5 and the gate of the first transistor T8 can share the same light-emitting control line, which can save at least one of the second control line and the potential transmission line, and is also beneficial for saving the space occupied by the pixel circuit and improving the density of the pixel circuit or the aperture ratio of the display panel.

[0061] In one embodiment, the pixel circuit further includes a second capacitor Cst, ie, a storage capacitor. One end of the second capacitor Cst is connected to the gate of the driving transistor T1 , and the other end of the second capacitor Cst is connected to the first power line.

[0062] In one embodiment, the pixel circuit further includes a write transistor T2 and a compensation transistor T3, one of the source or drain of the write transistor T2 is connected to the data line, the other of the source or drain of the write transistor T2 is connected to the other of the source or drain of the drive transistor T1, and the gate of the write transistor T2 is connected to the gate of the first initialization transistor T7; one of the source or drain of the compensation transistor T3 is connected to one of the source or drain of the drive transistor T1, the other of the source or drain of the compensation transistor T3 is connected to the gate of the drive transistor T1, and the gate of the compensation transistor T3 is connected to the gate of the first initialization transistor T7.

[0063] It should be noted that the gate of the write transistor T2, the gate of the compensation transistor T3 and the gate of the first initialization transistor T7 can share the same first control line, which is also beneficial to saving the space occupied by the pixel circuit and improving the density of the pixel circuit or the aperture ratio of the display panel.

[0064] In one embodiment, at least one of the driving transistor T1, the first light emission control transistor T6, the second light emission control transistor T5, the first initialization transistor T7, the second initialization transistor T4, the write transistor T2, and the compensation transistor T3 may be, but is not limited to, an N-channel thin film transistor, and may specifically be a metal oxide thin film transistor, such as an indium gallium zinc oxide thin film transistor. Alternatively, at least one of the driving transistor T1, the first light emission control transistor T6, the second light emission control transistor T5, the first initialization transistor T7, the second initialization transistor T4, the write transistor T2, and the compensation transistor T3 may also be a P-channel thin film transistor, and may specifically be a polysilicon thin film transistor, such as a low-temperature polysilicon thin film transistor.

[0065] Figure 5 for Figure 4 The timing diagram of the pixel circuit shown is as follows: Figures 5 to 8 As shown, Figure 4 The operation of the pixel circuit shown is as follows:

[0066] In the T3' period, see Figure 8 , the light emitting control signal EM is set low, the first light emitting control transistor T6, the second light emitting control transistor T5 and the first transistor T8 are turned on or turned on, the first power supply signal ELVDD is controlled by the driving transistor T1 to drive the light emitting device D1 to emit light, and the potential at point C (V C ) and the anode potential of the light-emitting device D1 (V EL ) is the same, that is, V C =V EL +V SS , where V SS is the cathode potential of the light emitting device D1.

[0067] In the T1 period, please refer to Figure 6 , the scanning signal Pscan(n-1) is set low, the second initialization transistor T4 is turned on, and the second initialization signal VI1 resets the lower plate of the second capacitor Cst.

[0068] In the T2 period, see Figure 7, the scanning signal Pscan(n) is set low, the writing transistor T2, the driving transistor T1, the compensation transistor T3 and the first initialization transistor T7 are turned on, and the data signal Data is sequentially written into the lower plate of the second capacitor Cst through the writing transistor T2, the driving transistor T1 and the compensation transistor T3; at the same time, the first initialization signal VI2 resets the point C (i.e., one plate of the first capacitor C2, such as the lower plate). At this time, the current I flowing through the first initialization transistor T7 VI2 It can be roughly estimated as:

[0069] I VI2 =2π*f*C2*(V C -V VI2 )=2π*f*C2*(V EL +V SS -V VI2 ) (3)

[0070] Wherein, f is the frequency of the scanning signal Pscan(n-1). VI2 is the potential of the first initialization signal VI2. C2 is the capacitance of the first capacitor C2. V C for Figure 4 The potential at point C. V EL is the anode potential of the light emitting device D1.

[0071] That is, in period T2, the first initialization transistor T7 is in the on state to reset the potential of point C, and the first light emission control transistor T6 and the first transistor T8 are both in the off state to avoid changing the potential of other nodes except point C.

[0072] In the T3 period, please refer to Figure 8 , the light emitting control signal EM is set low, the first light emitting control transistor T6, the second light emitting control transistor T5, the driving transistor T1 and the first transistor T8 are turned on, and the light emitting device D1 starts to emit light. In this stage, the current flowing from point B to point C is I BC , the current (i.e., the light-emitting current) flowing into the second power line through the light-emitting device D1 is I VSS I BC ,I VSS and I VI2 The three also satisfy the relationship of the above formula 2, that is, I BC =I VSS +I VI2 Among them, the self capacitance C of the light emitting device D1 EL The charges in the capacitor C2 will flow to the first capacitor C2 to initialize the anode potential of the light emitting device D1.

[0073] Through Figure 4By analyzing the working process of the pixel circuit shown in FIG. 1 , it can be found that due to the current I VI2 Not with the self-capacitance C of the light emitting device D1 EL , so in I BC Keeping the same, I VSS It also does not follow the capacitance C of the light emitting device D1. EL The brightness of the light emitting device D1 in the pixel circuit can be kept stable due to the change of its own characteristics, thereby improving or avoiding the brightness change caused by the change of its own characteristics.

[0074] In one embodiment, the on-time period of the first light emitting control transistor T6 is the same as the on-time period of the first transistor T8.

[0075] It should be noted that the cut-off time period of the first light emitting control transistor T6 and the cut-off time period of the first transistor T8 may also be the same, which can not only meet the working requirements of the pixel circuit but also reduce the control complexity of the pixel circuit.

[0076] In one of the embodiments, in one frame time of the pixel circuit, the start time when the first transistor T8 is in the off state is earlier than or equal to the start time when the first initialization transistor T7 is in the on state, and the end time when the first transistor T8 is in the off state is later than or equal to the end time when the first initialization transistor T7 is in the on state.

[0077] It should be noted that, in this embodiment, the first initialization transistor T7 can reset the point C before the self-capacitance C of the light emitting device D1 is reset. EL The charges in the capacitor C2 are transferred to the first capacitor C2 to reset the anode potential of the light emitting device D1.

[0078] In one embodiment, the present embodiment provides a display panel, which includes a plurality of pixel circuits in the above embodiments.

[0079] It can be understood that the display panel provided in this embodiment couples the first transistor T8 and the first capacitor C2 between the first light emitting control transistor T6 and the light emitting device D1, so that the reset current flowing through the first initialization transistor T7 and the self-capacitor C EL The reset current is not related to the first capacitor C2, because the change of the capacitance of the first capacitor C2 over time is almost negligible, which makes the reset current remain unchanged, that is, it will not change with the capacitance C of the light emitting device D1. ELThe reset current is a part of the light-emitting current flowing through the first light-emitting control transistor T6. Therefore, when the reset current and the light-emitting current flowing through the first light-emitting control transistor T6 remain unchanged, the light-emitting current flowing through the light-emitting device D1, which is another part of the light-emitting current flowing through the first light-emitting control transistor T6, can be kept constant, thereby reducing or avoiding the self-capacitance C of the light-emitting device D1. EL The effect of changes in its luminous brightness.

[0080] In one embodiment, in the same display panel, the capacitance of the first capacitor C2 in different pixel circuits is fixed and equal.

[0081] It should be noted that according to the above Figure 3 As can be seen from the description, due to the self-capacitance C of the light-emitting devices D1 of different colors EL The different changes in the values ​​of will cause the display panel to present a color shift phenomenon on the overall display. Therefore, in this embodiment, the capacitance of each first capacitor C2 is fixed and equal in different pixel circuits, which can avoid or improve the difference in the capacitance C of the light emitting devices D1 of different colors. EL Different changes in the amount of have different degrees of influence on the brightness of the light-emitting device D1, thereby improving the color shift phenomenon that occurs when the display panel works for a long time or at high temperature and high humidity.

[0082] 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.

[0083] 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 comprises: First power cord; Second power cord; A driving transistor, a first light-emitting control transistor, a first transistor and a light-emitting device are sequentially connected in series between the first power line and the second power line; A first node, located between the first light emission control transistor and the first transistor; A first initialization line electrically connected to the first node through a first initialization transistor; A first capacitor connected between the first node and a potential transmission line, the first capacitor being used to store charges in the self-capacitance of the light-emitting device in a light-emitting stage; The first transistor is used to control the charge in the self-capacitor of the light-emitting device to be transferred to the first capacitor during the light-emitting phase.

2. The pixel circuit according to claim 1, characterized in that: A gate of the first light emission control transistor is connected to a light emission control line, a gate of the first initialization transistor is connected to a first control line, and a gate of the first transistor is connected to a second control line.

3. The pixel circuit according to claim 1, characterized in that: The potential transmission line is used to transmit a constant voltage signal.

4. The pixel circuit according to claim 1, characterized in that: The potential transmission line is one of the first power line, the first initialization line, or the second power line.

5. The pixel circuit according to claim 2, characterized in that: A channel type of the first light emission control transistor is the same as a channel type of the first transistor, and the second control line is the light emission control line.

6. The pixel circuit according to claim 2, characterized in that: The pixel circuit further includes a second initialization transistor, one of a source or a drain of the second initialization transistor is connected to the gate of the driving transistor, the other of the source or the drain of the second initialization transistor is connected to a second initialization line, and the gate of the second initialization transistor is connected to a third control line; Wherein, the potential transmission line is the first power line or the second initialization line.

7. The pixel circuit according to claim 6, characterized in that: The pixel circuit also includes a second light-emitting control transistor, one of the source or the drain of the second light-emitting control transistor is connected to the other of the source or the drain of the driving transistor, the other of the source or the drain of the second light-emitting control transistor is connected to the first power line, and the gate of the second light-emitting control transistor is connected to the light-emitting control line or the second control line.

8. The pixel circuit according to claim 1, characterized in that: In the writing phase of the pixel circuit, the first initialization line receives a first initialization signal, the first light emitting control transistor and the first transistor are both in a cut-off state, and the first initialization signal is transmitted to the first capacitor through the first initialization transistor.

9. The pixel circuit according to claim 7, characterized in that: In the light emitting stage of the pixel circuit, the first light emitting control transistor, the second light emitting control transistor, the driving transistor and the first transistor are turned on, and the charge in the self-capacitance of the light emitting device flows to the first capacitor through the first transistor.

10. A display panel, characterized in that: The display panel comprises a plurality of pixel circuits as described in any one of claims 1 to 9.

11. The display panel according to claim 10, characterized in that: In the same display panel, the capacitance of the first capacitor in different pixel circuits is fixed and equal.

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