Pixel circuit, driving method thereof and display device

Abstract

Embodiments of the present application disclose a pixel circuit, a driving method thereof and a display device. Since a channel material of a driving transistor is a material with hysteresis effect, the driving transistor has hysteresis effect. In a data writing stage, the driving transistor is turned on to write a data voltage. In a light emitting stage, due to the hysteresis effect of the driving transistor, even if a gate voltage of the driving transistor is turned off, a source-drain current of the driving transistor is still greater than an off-state current of the driving transistor, and the driving transistor is still in an on state. Therefore, the pixel circuit provided by the embodiments of the present application can realize a storage function without an additional capacitor device, so that the pixel circuit can save one capacitor device. Since there is no capacitor device in the pixel circuit, a process flow for manufacturing the capacitor device can be saved, cost is reduced, light emitting brightness is improved, power consumption is reduced, pixel space is released, pixel size is reduced, and pixel resolution is improved.

Description

Technical Field

[0001] This invention relates to the field of display technology, and in particular to a pixel circuit, its driving method, and a display device. Background Technology

[0002] Organic light-emitting diode (OLED) displays offer advantages over traditional liquid crystal displays (LCDs) such as self-illumination, wide color gamut, high contrast, and thinness, making them widely used in mobile phones, tablets, and flexible wearable devices like smartwatches. Typically, pixel circuits are located in the display area, while gate driving circuits (such as GOA driving circuits) are located in the bezel area to provide driving signals to the pixel circuits, driving the light-emitting devices to emit light. Summary of the Invention

[0003] The present invention provides a pixel circuit, its driving method and display device. Since there are no capacitors in the pixel circuit, the manufacturing process of capacitors can be saved, the cost can be reduced, the brightness can be improved, the power consumption can be reduced, and the pixel space can be freed up, the device size can be reduced and the pixel resolution can be improved.

[0004] An embodiment of the present invention provides a pixel circuit, comprising: a control module, a driving transistor, and a light-emitting device; wherein, the channel material of the driving transistor is a material with a hysteresis effect; wherein,

[0005] The control module is configured to input a data voltage to the driving transistor;

[0006] The driving transistor is configured to be in a conducting state after the input data voltage is stopped, and to generate a driving current based on the data voltage to drive the light-emitting device to emit light.

[0007] Optionally, in the pixel circuit provided in the embodiments of the present invention, the driving transistor has a hysteresis effect, so that the pixel circuit reduces the number of at least one capacitor.

[0008] Optionally, in the pixel circuit provided in the embodiments of the present invention, the channel material of the driving transistor includes carbon nanotubes.

[0009] Optionally, in the pixel circuit provided in the embodiments of the present invention, the pixel circuit is electrically connected to the data signal line, and the data signal line is multiplexed as a reset signal line.

[0010] Optionally, in the pixel circuit provided in the embodiments of the present invention, the pixel circuit is electrically connected to the reset signal line, and the reset signal line is electrically connected to the gate of the driving transistor.

[0011] Optionally, in the pixel circuit provided in the embodiments of the present invention, the pixel circuit is electrically connected to the reset signal line, and the reset signal line is electrically connected to the gate of the gate reset transistor in the pixel circuit.

[0012] Optionally, in the pixel circuit provided in the embodiments of the present invention, the control module includes a switching transistor, the gate of the switching transistor is electrically connected to the scan signal line, the first terminal of the switching transistor is electrically connected to the data signal line, the second terminal of the switching transistor is electrically connected to the gate of the driving transistor, the first terminal of the driving transistor is electrically connected to the first power supply line, the second terminal of the driving transistor is electrically connected to the anode of the light-emitting device, and the cathode of the light-emitting device is electrically connected to the second power supply line.

[0013] Optionally, in the pixel circuit provided in the embodiments of the present invention, the control module includes a gate reset transistor, a first light-emitting control transistor, a second light-emitting control transistor, a first data writing transistor, and a second data writing transistor; wherein,

[0014] The gate of the gate reset transistor is electrically connected to the reset signal line, the first terminal of the gate reset transistor is electrically connected to the initialization signal line, and the second terminal of the gate reset transistor is electrically connected to the gate of the driving transistor.

[0015] The gate of the first light-emitting control transistor is electrically connected to the light-emitting control line, the first electrode of the first light-emitting control transistor is electrically connected to the first power supply line, and the second electrode of the first light-emitting control transistor is electrically connected to the first electrode of the driving transistor.

[0016] The gate of the second light-emitting control transistor is electrically connected to the light-emitting control line, the first terminal of the second light-emitting control transistor is electrically connected to the second terminal of the driving transistor, the second terminal of the second light-emitting control transistor is electrically connected to the anode of the light-emitting device, and the cathode of the light-emitting device is electrically connected to the second power supply line.

[0017] The gate of the first data writing transistor is electrically connected to the scan signal line, the first electrode of the first data writing transistor is electrically connected to the data signal line, and the second electrode of the first data writing transistor is electrically connected to the first electrode of the driving transistor.

[0018] The gate of the second data writing transistor is electrically connected to the scan signal line, the first terminal of the second data writing transistor is electrically connected to the gate of the driving transistor, and the second terminal of the second data writing transistor is electrically connected to the second terminal of the driving transistor.

[0019] Accordingly, embodiments of the present invention also provide a display device, including a display panel, wherein the display panel includes the pixel circuit provided in the embodiments of the present invention.

[0020] Accordingly, embodiments of the present invention also provide a driving method for a pixel circuit, used to drive the pixel circuit provided in the embodiments of the present invention, the driving method comprising:

[0021] During the reset phase, a reset voltage is input to the gate of the driving transistor to make the gate voltage of the driving transistor the initial voltage.

[0022] During the data writing phase, the control module inputs a data voltage to the driving transistor;

[0023] During the light-emitting stage, the driving transistor generates a driving current based on the data voltage, driving the light-emitting device to emit light.

[0024] Optionally, in the driving method provided in the embodiments of the present invention, the data writing stage specifically includes:

[0025] The data signal line applies a data voltage to the driving transistor, causing the gate voltage of the driving transistor to change from the initial voltage to the applied data voltage; wherein the potential of the applied data voltage is opposite to the potential of the initial voltage, and the source-drain current of the driving transistor corresponding to the applied data voltage is greater than its off-state current; the process of changing from the initial voltage to the applied data voltage involves at least one intermediate state voltage, the potential of the intermediate state voltage is the same as the potential of the applied data voltage, and the intermediate state voltage is less than the applied data voltage.

[0026] Optionally, in the driving method provided in the embodiments of the present invention, the light emission stage specifically includes:

[0027] The voltage on the signal line that applies the gate voltage to the gate of the driving transistor is turned off, so that the gate voltage of the driving transistor changes from the applied data voltage to 0. The source-drain current of the driving transistor is greater than its off-state current, so that the driving transistor is in the on state to drive the light-emitting device to emit light. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of a pixel circuit provided in an embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of another pixel circuit provided in an embodiment of the present invention;

[0030] Figure 3The Id-Vg curves are obtained from experimental testing when carbon nanotubes are used as channel materials for driving transistors.

[0031] Figure 4 This is a schematic diagram of another pixel circuit provided in an embodiment of the present invention;

[0032] Figure 5 This is a schematic diagram of another pixel circuit provided in an embodiment of the present invention;

[0033] Figure 6 This is a schematic diagram of another pixel circuit provided in an embodiment of the present invention;

[0034] Figure 7 This is a schematic diagram of another pixel circuit provided in an embodiment of the present invention;

[0035] Figure 8 for Figure 1 The timing diagram of the pixel circuit shown is shown below.

[0036] Figure 9A I for P-type drive transistor DS -V g Hysteresis curve;

[0037] Figure 9B for Figure 1 The diagram shows the gate voltage variation of the driving transistor.

[0038] Figure 10A I for N-type drive transistor DS -V g Hysteresis curve;

[0039] Figure 10B for Figure 4 The diagram shows the gate voltage variation of the driving transistor.

[0040] Figure 11 for Figure 5 The timing diagram of the pixel circuit shown is shown below.

[0041] Figure 12 for Figure 5 The diagram shows the gate voltage variation of the driving transistor.

[0042] Figure 13 This is a schematic flowchart of a pixel circuit driving method provided in an embodiment of the present invention;

[0043] Figure 14 I for two driving transistors with different threshold voltages (Vth) DS -V g Schematic diagram of hysteresis curve;

[0044] Figure 15 This is a schematic diagram of the structure of a display device provided in an embodiment of the present invention. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Furthermore, the embodiments and features in the embodiments of the present invention can be combined with each other without conflict. Based on the described embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] Currently, existing pixel circuits typically consist of several source TFTs (STFTs), one drive TFT (DTFT), and a storage capacitor (Cst). In LCD pixel circuits, a smaller area occupied by opaque devices is beneficial for brightness improvement, while the presence of the storage capacitor blocks some light transmission. In OLED pixel circuits, the bottom-emitting structure is similar to that of LCD pixel circuits; a smaller pixel area (larger aperture ratio) is beneficial for screen brightness improvement. If OLEDs use a top-emitting structure, although there is no aperture ratio issue, eliminating the storage capacitor simplifies design and manufacturing processes, and fewer components also reduce the probability of failure.

[0047] This invention provides a pixel circuit, such as... Figure 1 and Figure 2 As shown, it includes: a control module 1, a driving transistor DT, and a light-emitting device L; the channel material of the driving transistor DT is a material with a hysteresis effect; wherein,

[0048] Control module 1 is configured to input a data voltage to the drive transistor DT;

[0049] The driving transistor DT is configured to be in the on state after the input data voltage is stopped, and to generate a driving current based on the data voltage to drive the light-emitting device L to emit light.

[0050] The pixel circuit provided in this embodiment of the invention has a hysteresis effect because the channel material of the driving transistor is a material with a hysteresis effect. During the data writing stage, the driving transistor is turned on to write the data voltage. During the light emission stage, due to the hysteresis effect of the driving transistor, even if the gate voltage of the driving transistor is turned off, the source-drain current of the driving transistor is still greater than its off-state current. Therefore, the driving transistor is still in the on state. Thus, the pixel circuit provided in this embodiment of the invention does not need to set an additional capacitor to realize the storage function, thereby saving a capacitor in the pixel circuit. Since there is no capacitor in the pixel circuit, the process of manufacturing the capacitor can be saved, the cost can be reduced, and the light emission brightness can be improved, the power consumption can be reduced, and the pixel space can be freed up, the pixel size can be reduced, and the pixel resolution (high PPI) can be improved.

[0051] In specific implementation, in the pixel circuit provided in the embodiments of the present invention, such as Figure 1 and Figure 2 As shown, the driving transistor DT has a hysteresis effect, which allows the pixel circuit to reduce the setting of at least one capacitor (e.g., the capacitor is the storage capacitor Cst of the pixel circuit in the related art). This can save the process of manufacturing the capacitor, reduce the cost, and at the same time improve the brightness, reduce the power consumption, free up pixel space, reduce the pixel size, and improve the pixel resolution.

[0052] In specific implementation, in the pixel circuit provided in the embodiments of the present invention, such as Figure 1 and Figure 2 As shown, the channel material for driving the transistor DT can include carbon nanotubes. Specifically, carbon nanotubes have a mobility of up to 10-1. 5 cm 2 / VS, carbon nanotubes, as channel materials for TFTs, are expected to significantly reduce the current and size of display devices, exhibiting high PPI and energy efficiency, and are poised to become the next-generation channel material. Furthermore, carbon nanotubes readily adsorb water molecules and oxygen when exposed to air. These oxygen and water molecules simultaneously adsorb on the carbon nanotube surface, forming a redox pair. This redox pair system allows for charge transfer between the carbon nanotube and the redox pair. Moreover, the chemical potential of this redox pair system is close to the valence band position of the carbon nanotube. When electrochemical equilibrium is reached, the Fermi level of the carbon nanotube is confined near the valence band, preventing electron carrier conduction in the transistor channel. Therefore, the driving transistor obtained using carbon nanotubes as the channel material under air exposure conditions is a P-type transistor. In addition, the water and oxygen adsorbed on the carbon nanotube surface and the mobile ions between the carbon nanotube and the transistor can also cause hysteresis in the driving transistor, such as... Figure 3 As shown, Figure 3The figure shows the Id-Vg curve obtained from experimental testing when carbon nanotubes are used as the channel material for the driving transistor. This curve indicates that the driving transistor with carbon nanotubes as the channel material exhibits a hysteresis effect. Therefore, this embodiment of the invention utilizes carbon nanotubes as the channel material for the driving transistor, enabling the transistor to exhibit hysteresis characteristics. This allows the pixel circuit to save on one capacitor. Since there is no capacitor in the pixel circuit, the manufacturing process for the capacitor is simplified, reducing costs. Simultaneously, it also improves luminous brightness, reduces power consumption, frees up pixel space, reduces pixel size, and improves pixel resolution.

[0053] Specifically, such as Figure 1 and Figure 2 As shown, the driving transistor DT is a P-type transistor. A P-type transistor is turned on when the voltage level is low and turned off when the voltage level is high.

[0054] In specific implementations, in the pixel circuit provided in the embodiments of the present invention, MgO / Al2O3 or HfO2 can be doped inside the carbon nanotubes or coated on the surface of the carbon nanotubes, thus obtaining an N-type driving transistor, such as... Figure 4 and Figure 5 As shown, an N-type transistor is turned on when a high-level voltage is applied and turned off when a low-level voltage is applied.

[0055] It should be noted that the channel material for driving transistors in the pixel circuit provided in this embodiment of the invention is carbon nanotubes with hysteresis effect as an example. Of course, materials with hysteresis effect are not limited to carbon nanotubes provided in this embodiment of the invention, but are also applicable to any other material that can be used as a channel material and has hysteresis effect, such as oxides such as Si and IGZO, LTPO, LTPS, graphene, MoS2, etc.; the process for making the channel material have hysteresis effect includes, but is not limited to, doping, annealing, plasma treatment, covering dielectric layer, etc.

[0056] In practical implementation, the pixel circuit's operation mainly includes a data writing stage and a light-emitting stage. Due to the hysteresis effect of the driving transistor, if the potential of the next frame's control signal is lower than the potential of the previous frame's control signal, the driving transistor remains in the state of the previous control signal, rendering the control signal input for the next frame invalid. Therefore, before the control signal for the next frame is input, the gate of the driving transistor needs to be reset. In the pixel circuit provided in this embodiment of the invention, as shown... Figure 1 and Figure 4 As shown, the pixel circuit is electrically connected to the data signal line Data, which can be multiplexed as the reset signal line Reset. Thus, before data is written, a reset voltage can be applied to the gate of the driving transistor DT using the data signal line Data, bringing DT to its initial state.

[0057] Optionally, in the pixel circuit provided in the embodiments of the present invention, as follows: Figure 6 and Figure 7 As shown, the pixel circuit is electrically connected to the reset signal line Reset, which is also electrically connected to the gate of the driving transistor DT. Thus, before data voltage is written, a reset voltage can be applied to the gate of the driving transistor DT using the reset signal line Reset, bringing the driving transistor DT to its initial state.

[0058] In specific implementation, in the pixel circuit provided in the embodiments of the present invention, such as Figure 1 , Figure 4 , Figure 6 and Figure 7 As shown, the control module 1 may include a switching transistor ST, the gate of the switching transistor ST is electrically connected to the scan signal line Gate, the first terminal of the switching transistor ST is electrically connected to the data signal line Data, the second terminal of the switching transistor ST is electrically connected to the gate of the driving transistor DT, the first terminal of the driving transistor DT is electrically connected to the first power supply line VDD, the second terminal of the driving transistor DT is electrically connected to the anode of the light-emitting device L, and the cathode of the light-emitting device L is electrically connected to the second power supply line VSS.

[0059] Optionally, such as Figure 1 and Figure 6 As shown, all transistors are P-type transistors; Figure 4 and Figure 7 As shown, all transistors are N-type transistors; this allows for a standardized manufacturing process.

[0060] The following is based on Figure 1 The working process of the P-type pixel circuit shown is explained using this example. The working timing is as follows: Figure 8 As shown, the I of the P-type driving transistor DT DS -V g Hysteresis curve as shown Figure 9A As shown.

[0061] like Figure 9B As shown, in the first frame, assuming the initial gate voltage of the P-type driving transistor DT is point A, by... Figure 1 The pixel circuit shown and Figure 8 As shown in the timing diagram, in the first stage t1 (reset stage), a scan voltage is applied to the gate of the switching transistor ST through the scan signal line Gate, turning on the switching transistor ST. The data signal line Data first transmits the reset voltage to the gate of the driving transistor DT, resetting the gate voltage of the driving transistor DT to the initial voltage (e.g., Figure 9BPoint A). In the second stage t2 (data writing stage), the scan signal line Gate applies a scan voltage to the gate of the switching transistor ST to turn on the switching transistor ST, and the data signal line Data applies a data voltage to the driving transistor DT (e.g., its gate), causing the gate voltage of the driving transistor DT to change from the initial voltage (point A) to the applied data voltage (point C); wherein, the potential of the applied data voltage (point C) is opposite to the potential of the initial voltage (point A), and the source-drain current I of the driving transistor DT corresponding to the applied data voltage (point C) is... DS Greater than its off-state current I off The process of changing from the initial voltage (point A) to the applied data voltage (point C) involves at least one intermediate voltage state (e.g., point B). The potential of the intermediate voltage (point B) is the same as the potential of the applied data voltage (point C), and the intermediate voltage (point B) is less than the applied data voltage (point C). That is, the gate voltage of the driving transistor DT changes from the initial voltage (point A) to the applied data voltage (point C) through a process of A→B→C. This change is due to the hysteresis effect of the driving transistor DT. In the third stage t3 (light-emitting stage), the voltage on the signal line that applies the gate voltage to the gate of the driving transistor DT is turned off (e.g., the data voltage on the data signal line Data and the scan voltage on the scan signal line Gate are turned off), causing the gate voltage of the driving transistor to change from the applied data voltage to 0, and the gate voltage V of the driving transistor DT to change to 0. g As the applied data voltage (point C) changes to 0 (point D), due to the hysteresis effect of the driving transistor DT, the gate voltage V of the driving transistor DT... g Although it drops to 0, the source-drain current I of the driving transistor DT DS Greater than its off-state current I off Therefore, due to the hysteresis effect of the driving transistor DT, the driving transistor DT remains in an on-state to drive the light-emitting device L to emit light. Thus, the driving transistor in the pixel circuit provided by this embodiment of the invention has a hysteresis effect, which can save the installation of a capacitor, simplify the manufacturing process of the capacitor, reduce costs, and simultaneously improve luminous brightness, reduce power consumption, free up pixel space, reduce pixel size, and improve pixel resolution.

[0062] However, due to the hysteresis effect of the driving transistor DT, if the gate voltage V of the driving transistor DT is lower in the second frame... g Less than the gate voltage V of the first frame g If the driving transistor DT remains in the state of the first frame, the gate voltage V input in the second frame will be affected. g Invalid. Therefore, the gate voltage of the driving transistor DT needs to be reset before the gate input data voltage of the second frame. Figure 9B Taking an initial gate voltage of -20V for the driving transistor DT as an example, in the second frame, under the control of the scan voltage on the scan signal line Gate, the switching transistor ST is turned on. The data signal line Data first transmits a reset voltage to the gate of the driving transistor DT, causing the device state to return from point D in the first frame to point A. Subsequently, the data signal line Data applies a new data voltage to the gate of the driving transistor DT, causing the gate voltage of the driving transistor DT to change from A→B→C'. Then, the new data voltage on the data signal line Data and the scan voltage on the scan signal line Gate are turned off, and the gate voltage V of the driving transistor DT... g From C'→D', we can see that the gate voltage V of the driving transistor DT is... g Although it drops to 0, the source-drain current I of the driving transistor DT DS Greater than its off-state current I off Therefore, due to the hysteresis effect of the driving transistor DT, the driving transistor DT is still in the state where it can be turned on, so as to drive the light-emitting device L to emit light.

[0063] The following is based on Figure 4 The following explanation uses the N-type pixel circuit as an example to illustrate its operation, with the timing sequence as follows: Figure 8 As shown, the I of the N-type drive transistor DT DS -V g Hysteresis curve as shown Figure 10A As shown.

[0064] like Figure 10B As shown, in the first frame, assuming the initial gate voltage of the N-type driving transistor DT is point A, by... Figure 4 The pixel circuit shown and Figure 8 As shown in the timing diagram, in the first stage t1 (reset stage), a scan voltage is applied to the gate of the switching transistor ST through the scan signal line Gate, turning on the switching transistor ST. The data signal line Data first transmits the reset voltage to the gate of the driving transistor DT, resetting the gate voltage of the driving transistor DT to the initial voltage (e.g., Figure 10B Point A). In the second stage t2 (data writing stage), the scan signal line Gate applies a scan voltage to the gate of the switching transistor ST to turn on the switching transistor ST, and the data signal line Data applies a data voltage to the driving transistor DT (e.g., its gate), causing the gate voltage of the driving transistor DT to change from the initial voltage (point A) to the applied data voltage (point C); wherein, the potential of the applied data voltage (point C) is opposite to the potential of the initial voltage (point A), and the source-drain current I of the driving transistor DT corresponding to the applied data voltage (point C) is... DS Greater than its off-state current I offThe process of changing from the initial voltage (point A) to the applied data voltage (point C) involves at least one intermediate voltage state (e.g., point B). The potential of the intermediate voltage (point B) is the same as the potential of the applied data voltage (point C), and the intermediate voltage (point B) is less than the applied data voltage (point C). That is, the gate voltage of the driving transistor DT changes from the initial voltage (point A) to the applied data voltage (point C) through a process of A→B→C. This change is due to the hysteresis effect of the driving transistor DT. In the third stage t3 (light-emitting stage), the voltage on the signal line that applies the gate voltage to the gate of the driving transistor DT is turned off (e.g., the data voltage on the data signal line Data and the scan voltage on the scan signal line Gate are turned off), causing the gate voltage of the driving transistor to change from the applied data voltage to 0, and the gate voltage V of the driving transistor DT to change to 0. g As the applied data voltage (point C) changes to 0 (point D), due to the hysteresis effect of the driving transistor DT, the gate voltage V of the driving transistor DT... g Although it drops to 0, the source-drain current I of the driving transistor DT DS Greater than its off-state current I off Therefore, due to the hysteresis effect of the driving transistor DT, the driving transistor DT remains in an on-state to drive the light-emitting device L to emit light. Thus, the driving transistor in the pixel circuit provided by this embodiment of the invention has a hysteresis effect, which can save the installation of a capacitor, simplify the manufacturing process of the capacitor, reduce costs, and simultaneously improve luminous brightness, reduce power consumption, free up pixel space, reduce pixel size, and improve pixel resolution.

[0065] Specifically, Figure 10B The working principle of the second frame and Figure 9B The working principle is the same in the second frame. Before the data voltage is input to the gate of the driving transistor DT in the second frame, the gate voltage of the driving transistor DT needs to be reset so that the gate voltage of the driving transistor DT returns from point D in the first frame to point A. Then, the data signal line Data loads a new data voltage (for example, it can be less than the voltage at point C in the first frame) onto the gate of the driving transistor DT. Then, the new data voltage on the data signal line Data and the scan voltage on the scan signal line Gate are turned off, and the gate voltage V of the driving transistor DT is reduced. g It drops to 0, but the source-drain current I of the driving transistor DT is reduced to 0. DS Greater than its off-state current I off Therefore, due to the hysteresis effect of the driving transistor DT, the driving transistor DT is still in the state that can be turned on, so as to drive the light-emitting device L to emit light.

[0066] Optionally, in the pixel circuit provided in the embodiments of the present invention, as follows: Figure 2 and Figure 5 As shown, the pixel circuit is electrically connected to the reset signal line Reset, which is also electrically connected to the gate of the gate reset transistor (T1) in the pixel circuit. Thus, before data voltage is written, a reset voltage can be applied to the gate of the gate reset transistor T1 using the reset signal line Reset, and an initial voltage can be applied to the gate of the driving transistor DT using the initialization signal line Vinit, thereby putting the driving transistor DT into its initial state.

[0067] In specific implementation, in the pixel circuit provided in the embodiments of the present invention, such as Figure 2 and Figure 5 As shown, the control module 1 may include a gate reset transistor T1, a first light-emitting control transistor T2, a second light-emitting control transistor T3, a first data writing transistor T4, and a second data writing transistor T5; wherein,

[0068] The gate of the gate reset transistor T1 is electrically connected to the reset signal line Reset, the first terminal of the gate reset transistor T1 is electrically connected to the initialization signal line Vinit, and the second terminal of the gate reset transistor T1 is electrically connected to the gate of the drive transistor DT.

[0069] The gate of the first light-emitting control transistor T2 is electrically connected to the light-emitting control line EM, the first terminal of the first light-emitting control transistor T2 is electrically connected to the first power supply line VDD, and the second terminal of the first light-emitting control transistor T2 is electrically connected to the first terminal of the driving transistor DT.

[0070] The gate of the second light-emitting control transistor T3 is electrically connected to the light-emitting control line EM, the first terminal of the second light-emitting control transistor T3 is electrically connected to the second terminal of the driving transistor DT, the second terminal of the second light-emitting control transistor T3 is electrically connected to the anode of the light-emitting device L, and the cathode of the light-emitting device L is electrically connected to the second power supply line VSS.

[0071] The gate of the first data writing transistor T4 is electrically connected to the scan signal line Gate, the first terminal of the first data writing transistor T4 is electrically connected to the data signal line Data, and the second terminal of the first data writing transistor T4 is electrically connected to the first terminal of the driving transistor DT.

[0072] The gate of the second data writing transistor T5 is electrically connected to the scan signal line Gate, the first terminal of the second data writing transistor T5 is electrically connected to the gate of the driving transistor DT, and the second terminal of the second data writing transistor T5 is electrically connected to the second terminal of the driving transistor DT.

[0073] Optionally, such as Figure 2 As shown, all transistors are P-type transistors; Figure 5 As shown, all transistors are N-type transistors; this allows for a standardized manufacturing process.

[0074] The following is based on Figure 5 The following explanation uses the N-type pixel circuit as an example to illustrate its operation, with the timing sequence as follows: Figure 11 As shown.

[0075] like Figure 12 As shown, in the first stage t1 (reset stage), under the control of the reset voltage on the reset signal line Reset, the gate reset transistor T1 is turned on, and the initial voltage on the initialization signal line Vinit resets the gate voltage of the driving transistor DT. In this embodiment, the initial voltage is taken as +20V. At this time, the gate voltage of the driving transistor DT is the initial voltage (e.g., Figure 12 (Point A).

[0076] In the second stage t2 (data writing stage), under the control of the scan voltage on the scan signal line Gate, both the first data writing transistor T4 and the second data writing transistor T5 are turned on, causing the driving transistor DT to form a diode connection. The data signal line Data applies a data voltage to the driving transistor DT (e.g., its first terminal), and the gate voltage of the driving transistor DT changes from the initial voltage (point A) to the applied data voltage V. Data (Point C); where the potential of the applied data voltage (point C) is opposite to the potential of the initial voltage (point A), and the source-drain current I of the driving transistor DT corresponding to the applied data voltage (point C) is... DS Greater than its off-state current I off The process of changing from the initial voltage (point A) to the applied data voltage (point C) involves at least one intermediate voltage (e.g., point B). The potential of the intermediate voltage (point B) is the same as the potential of the applied data voltage (point C), and the intermediate voltage (point B) is less than the applied data voltage (point C). That is, the gate voltage of the driving transistor DT changes from the initial voltage (point A) to the applied data voltage (point C) through the process of A→B→C. This change process is due to the hysteresis effect of the driving transistor DT.

[0077] In the third stage t3 (light-emitting stage), the voltage on the signal line that applies the gate voltage to the gate of the driving transistor DT is turned off (e.g., the scan voltage on the scan signal line Gate and the reset voltage on the reset signal line Reset), causing the gate voltage of the driving transistor DT to change from the applied data voltage (point C) to 0 (point D). Simultaneously, under the control of the light-emitting control voltage on the light-emitting control line EM, both the first light-emitting control transistor T2 and the second light-emitting control transistor T3 are turned on. Due to the hysteresis effect of the driving transistor DT, the gate voltage V of the driving transistor DT... g Although it drops to 0, the source-drain current I of the driving transistor DT DS Greater than its off-state current I offTherefore, due to the hysteresis effect of the driving transistor DT, the driving transistor DT remains in an on-state, thus enabling the light-emitting device L to emit light in the third stage t3. Therefore, the driving transistor in the pixel circuit provided by this embodiment of the invention has a hysteresis effect, which can save the installation of a capacitor, reduce the manufacturing process of the capacitor, lower costs, and simultaneously improve luminous brightness, reduce power consumption, free up pixel space, reduce pixel size, and improve pixel resolution.

[0078] Specifically, Figure 12 The working principle of the second frame and Figure 9B The operating principle is the same in the second frame. Before the data voltage is input to the first terminal of the driving transistor DT in the second frame, the gate voltage of the driving transistor DT needs to be reset, so that the gate voltage of the driving transistor DT returns from point D in the first frame to point A. Then, the data signal line Data loads a new data voltage (for example, it can be less than the voltage at point C in the first frame) onto the first terminal of the driving transistor DT. Then, the scan voltage on the scan signal line Gate and the reset voltage on the reset signal line Reset are turned off, and the gate voltage V of the driving transistor DT... g It drops to 0, but the source-drain current I of the driving transistor DT is reduced to 0. DS Greater than its off-state current I off Therefore, due to the hysteresis effect of the driving transistor DT, the driving transistor DT is still in the state that can be turned on, so as to drive the light-emitting device L to emit light.

[0079] It should be noted that the embodiments of the present invention are illustrated using 2T and 6T pixel circuits as examples. The pixel circuits provided by the embodiments of the present invention can save the fabrication of one capacitor. Of course, the pixel circuits are not limited to 2T and 6T structures, and can also be 5T, 7T, etc., which are not limited here.

[0080] In summary, the pixel circuit provided by the embodiments of the invention can realize the storage function without the need for additional capacitors, thereby saving one capacitor in the pixel circuit. Since there are no capacitors in the pixel circuit, the manufacturing process of capacitors can be saved, reducing costs. At the same time, it can also improve light emission brightness, reduce power consumption, free up pixel space, reduce pixel size, and improve pixel resolution.

[0081] Based on the same inventive concept, embodiments of the present invention also provide a driving method for a pixel circuit, used to drive the pixel circuit provided in the embodiments of the present invention, such as... Figure 13 As shown, the driving method includes:

[0082] S1301, Reset phase: Input a reset voltage to the gate of the driving transistor to make the gate voltage of the driving transistor the initial voltage.

[0083] S1302, Data writing stage: The control module inputs data voltage to the driving transistor;

[0084] S1303, the light-emitting stage, the driving transistor generates a driving current based on the data voltage, driving the light-emitting device to emit light.

[0085] The pixel circuit driving method provided in this embodiment of the invention first resets the gate of the driving transistor to avoid the hysteresis effect of the driving transistor. If the potential of the control signal of the next frame is lower than that of the control signal of the previous frame, the driving transistor will still be in the state of the previous control signal, making the control signal input in the next frame invalid. Therefore, the gate of the driving transistor needs to be reset before the control signal of the next frame is input. In the data writing stage, the driving transistor is turned on to write the data voltage. In the light emission stage, due to the hysteresis effect of the driving transistor, even if the gate voltage of the driving transistor is turned off, the source-drain current of the driving transistor is still greater than its off-state current, and the driving transistor is still in the on state, driving the light emission device to emit light.

[0086] In specific implementation, the data writing stage in the driving method provided in the embodiments of the present invention can specifically be as follows:

[0087] A data signal line applies a data voltage to the driving transistor, causing the gate voltage of the driving transistor to change from the initial voltage to the applied data voltage. The potential of the applied data voltage is opposite to that of the initial voltage, and the source-drain current of the driving transistor corresponding to the applied data voltage is greater than its off-state current. The process of changing from the initial voltage to the applied data voltage involves at least one intermediate voltage, the potential of which is the same as that of the applied data voltage, and the intermediate voltage is less than the applied data voltage. Specifically, this driving method can be found in the aforementioned pixel circuit section... Figure 1 , Figure 4 and Figure 5 The driving principle of the pixel circuit shown is explained, but will not be elaborated here.

[0088] In specific implementation, the light emission stage in the driving method provided in the embodiments of the present invention can specifically be:

[0089] The voltage on the signal line that applies the gate voltage to the gate of the driving transistor is turned off, causing the gate voltage of the driving transistor to change from the applied data voltage to 0. This makes the source-drain current of the driving transistor greater than its off-state current, thus turning the driving transistor on to drive the light-emitting device to emit light. Specifically, the driving method for this part can be found in the aforementioned pixel circuit section. Figure 1 , Figure 4 and Figure 5 The driving principle of the pixel circuit shown is explained, but will not be elaborated here.

[0090] In practical implementation, the design intent of existing pixel circuits such as 6T1C and 7T1C is to eliminate the influence of threshold voltage (Vth) drift of the driving transistor on the characteristics of the driving transistor, thereby improving display uniformity. However, the driving transistor in this embodiment of the invention has a hysteresis effect and therefore does not require capacitors. Since the pixel circuit does not have the ability to eliminate threshold voltage (Vth) drift, the data voltage can be calibrated pixel by pixel. Specifically, as... Figure 14 As shown, Figure 14 I for two driving transistors with different threshold voltages (Vth) DS -V g Hysteresis curves: Before applying the gate input voltage to the driving transistors, it is necessary to test and record the hysteresis curve of each driving transistor. For example, if two driving transistors need to achieve the same current value (I), then the two driving transistors need to be supplied with different V values. g Values, in this example V A and V B This is to eliminate the uneven display caused by different threshold voltages (Vth) between different driving transistors.

[0091] Based on the same inventive concept, embodiments of the present invention also provide a display device, including a display panel, the display panel including the pixel circuit provided in the embodiments of the present invention. The principle by which this display device solves the problem is similar to that of the aforementioned pixel circuit, therefore, the implementation of this display device can refer to the implementation of the aforementioned pixel circuit, and the repeated parts will not be described again here.

[0092] In specific implementation, the display device provided in the embodiments of the present invention can be an organic light-emitting display device or a liquid crystal display device, and there is no limitation herein.

[0093] In specific implementation, the display device provided in the embodiments of the present invention can be a full-screen display device or a flexible display device, etc., and is not limited here.

[0094] In specific implementation, the display device provided in the embodiments of the present invention can be as follows: Figure 15 The image shows a full-screen mobile phone. Of course, the display device provided in this embodiment of the invention can also be any product or component with display function, such as a tablet computer, television, monitor, laptop computer, digital photo frame, or navigator. Other essential components of this display device are understood by those skilled in the art and will not be described in detail here, nor should they be construed as limiting the invention.

[0095] The pixel circuit, its driving method, and display device provided in this invention have a hysteresis effect because the channel material of the driving transistor is a material with a hysteresis effect. During the data writing stage, the driving transistor is turned on to write the data voltage. During the light emission stage, due to the hysteresis effect of the driving transistor, even if the gate voltage of the driving transistor is turned off, the source-drain current of the driving transistor is still greater than its off-state current, so the driving transistor is still in the on state. Therefore, the pixel circuit provided in this invention does not need to be additionally equipped with a capacitor to realize the storage function, thereby saving a capacitor in the pixel circuit. Since there is no capacitor in the pixel circuit, the process of manufacturing the capacitor can be saved, the cost can be reduced, and the light emission brightness can be improved, the power consumption can be reduced, and the pixel space can be freed up, the pixel size can be reduced, and the pixel resolution can be improved.

[0096] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A pixel circuit, characterized in that, include: The system includes a control module, a driving transistor, and a light-emitting device; the channel material of the driving transistor is a material with a hysteresis effect; wherein, The control module is configured to input a data voltage to the driving transistor; The driving transistor is configured to be in an on state after the input data voltage is stopped, and to generate a driving current based on the data voltage to drive the light-emitting device to emit light; The control module includes a switching transistor, the gate of which is electrically connected to a scan signal line, the first terminal of which is electrically connected to a data signal line, and the second terminal of which is electrically connected to the gate of a driving transistor. Specifically, inputting a data voltage to the driving transistor involves the data signal line applying a data voltage to the driving transistor, causing the gate voltage of the driving transistor to change from an initial voltage to the applied data voltage. The potential of the applied data voltage is opposite to the potential of the initial voltage, and the source-drain current of the driving transistor corresponding to the applied data voltage is greater than its off-state current. The process of changing from the initial voltage to the applied data voltage involves at least one intermediate state voltage, the potential of which is the same as the potential of the applied data voltage, and the intermediate state voltage is less than the applied data voltage.

2. The pixel circuit according to claim 1, characterized in that, The driving transistor has a hysteresis effect, which reduces the number of capacitors required in the pixel circuit.

3. The pixel circuit according to claim 1, characterized in that, The channel material of the driving transistor includes carbon nanotubes.

4. The pixel circuit according to claim 1, characterized in that, The pixel circuit is electrically connected to the data signal line, and the data signal line is multiplexed as a reset signal line.

5. The pixel circuit according to claim 1, characterized in that, The pixel circuit is electrically connected to the reset signal line, and the reset signal line is electrically connected to the gate of the driving transistor.

6. The pixel circuit according to claim 1, characterized in that, The pixel circuit is electrically connected to the reset signal line, and the reset signal line is electrically connected to the gate of the gate reset transistor in the pixel circuit.

7. The pixel circuit according to any one of claims 1-5, characterized in that, The first terminal of the driving transistor is electrically connected to the first power line, the second terminal of the driving transistor is electrically connected to the anode of the light-emitting device, and the cathode of the light-emitting device is electrically connected to the second power line.

8. The pixel circuit according to any one of claims 1-3 and 6, characterized in that, The control module includes a gate reset transistor, a first light-emitting control transistor, a second light-emitting control transistor, a first data writing transistor, and a second data writing transistor; wherein, The gate of the gate reset transistor is electrically connected to the reset signal line, the first terminal of the gate reset transistor is electrically connected to the initialization signal line, and the second terminal of the gate reset transistor is electrically connected to the gate of the driving transistor. The gate of the first light-emitting control transistor is electrically connected to the light-emitting control line, the first electrode of the first light-emitting control transistor is electrically connected to the first power supply line, and the second electrode of the first light-emitting control transistor is electrically connected to the first electrode of the driving transistor. The gate of the second light-emitting control transistor is electrically connected to the light-emitting control line, the first terminal of the second light-emitting control transistor is electrically connected to the second terminal of the driving transistor, the second terminal of the second light-emitting control transistor is electrically connected to the anode of the light-emitting device, and the cathode of the light-emitting device is electrically connected to the second power supply line. The gate of the first data writing transistor is electrically connected to the scan signal line, the first terminal of the first data writing transistor is electrically connected to the data signal line, and the second terminal of the first data writing transistor is electrically connected to the first terminal of the driving transistor. The gate of the second data writing transistor is electrically connected to the scan signal line, the first terminal of the second data writing transistor is electrically connected to the gate of the driving transistor, and the second terminal of the second data writing transistor is electrically connected to the second terminal of the driving transistor.

9. A display device, characterized in that, It includes a display panel, the display panel including the pixel circuitry as described in any one of claims 1-8.

10. A method for driving a pixel circuit, used to drive the pixel circuit as described in any one of claims 1-8, characterized in that, The driving method includes: During the reset phase, a reset voltage is input to the gate of the driving transistor to make the gate voltage of the driving transistor the initial voltage. During the data writing phase, the control module inputs a data voltage to the driving transistor; During the light-emitting stage, the driving transistor generates a driving current based on the data voltage to drive the light-emitting device to emit light. The data writing stage specifically involves: the data signal line applying a data voltage to the driving transistor, causing the gate voltage of the driving transistor to change from the initial voltage to the applied data voltage; wherein the potential of the applied data voltage is opposite to the potential of the initial voltage, and the source-drain current of the driving transistor corresponding to the applied data voltage is greater than its off-state current; the process of changing from the initial voltage to the applied data voltage involves at least one intermediate state voltage, the potential of the intermediate state voltage is the same as the potential of the applied data voltage, and the intermediate state voltage is less than the applied data voltage.

11. The driving method according to claim 10, characterized in that, The light-emitting stage specifically refers to: The voltage on the signal line that applies the gate voltage to the gate of the driving transistor is turned off, so that the gate voltage of the driving transistor changes from the applied data voltage to 0. The source-drain current of the driving transistor is greater than its off-state current, so that the driving transistor is in the on state to drive the light-emitting device to emit light.

Images