CN116206567A - Pixel circuit, pixel circuit driving method and display device - Google Patents

Abstract

The invention discloses a pixel circuit, a pixel circuit driving method and a display device, wherein the pixel circuit comprises a light emitting element and a parameter control circuit, the parameter control circuit is connected to the light emitting element and is configured to receive light emitting parameter information from a parameter input end, store the light emitting parameter information at a first node and adjust at least one light emitting parameter of the light emitting element according to the light emitting parameter information; the parameter input end and the first node comprise a first switching tube and a second switching tube which are mutually connected in parallel, and the conduction conditions of the first switching tube and the second switching tube are opposite; the pixel circuit is configured such that the first switching tube and the second switching tube are simultaneously turned on when the light emission parameter information is input to the parameter input terminal. The pixel circuit provided by the invention can adapt to the driving requirement of higher voltage or finer granularity, is suitable for the selection of various light-emitting elements, and widens the adjustable range of the light-emitting parameters.

Description

Pixel circuit, pixel circuit driving method and display device

technical field

The present invention relates to the field of display technology, in particular to a pixel circuit, a pixel circuit driving method and a display device.

Background technique

With the development of display technology, the application range of Organic Light Emitting Diode (OLED, Organic Light Emitting Diode), which has advantages such as active light emission, large viewing angle, low power consumption, fast response speed and high contrast ratio, has gradually expanded, and has the potential to replace traditional The trend of liquid crystal display (LCD, Liquid Crystal Display).

In the prior art, organic light-emitting diodes are usually driven by two driving methods, PMOLED (Passive Matrix OLED, passive matrix OLED) and AMOLED (Active Matrix OLED, active matrix OLED). The former has simple structure, low cost, However, the driving voltage is high, while the latter has the characteristics of low driving voltage and long luminous life, but high cost and difficult manufacturing process. For the AMOLED driving method widely used in the market, its low power consumption brings inherent advantages, but it will make it difficult to provide a finer gray scale adjustment range under the limitation of the driving voltage. Thin film transistors are relatively expensive, and in application scenarios with finer gray scale adjustment requirements and stronger output uniformity requirements, the "cost performance" of traditional AMOLED driving methods is not satisfactory.

Contents of the invention

One of the objectives of the present invention is to provide a pixel circuit to solve the technical problems in the prior art that the traditional AMOLED drive method can adjust the gray scale granularity coarsely, cannot adapt to various display scenarios, and is difficult to balance uniformity and continuous adjustability.

One of the objectives of the present invention is to provide a method for driving a pixel circuit.

One of the objectives of the present invention is to provide a display device.

To achieve one of the objectives of the above invention, an embodiment of the present invention provides a pixel circuit, including a light emitting element and a parameter control circuit, the parameter control circuit is connected to the light emitting element, and is configured to receive light parameter information from a parameter input terminal , store it at the first node, and adjust at least one light-emitting parameter of the light-emitting element according to the light-emitting parameter information; the parameter input terminal and the first node include first switching tubes connected in parallel The conduction conditions of the first switch tube and the second switch tube are opposite to those of the second switch tube; the pixel circuit is configured such that when the light emission parameter information is input to the parameter input terminal, the first switch tube tube and the second switch tube are turned on at the same time.

As a further improvement of an embodiment of the present invention, the first switch transistor and the second switch transistor are field effect transistors.

As a further improvement of an embodiment of the present invention, the first switch transistor is an N-type field effect transistor, and the second switch transistor is a P-type field effect transistor.

As a further improvement of an embodiment of the present invention, the parameter control circuit includes a third drive transistor and a storage capacitor; one end of the storage capacitor is connected to the gate of the third drive transistor to form the first node, so The other end of the storage capacitor is connected to the first end of the third driving tube.

As a further improvement of an embodiment of the present invention, the first end of the third drive tube is connected to the ground level to form the current output end of the parameter control circuit; the second end of the third drive tube is connected to the power supply level, forming the current input terminal of the parameter control circuit.

As a further improvement of an embodiment of the present invention, the anode of the light emitting element is connected to the power supply level, and the cathode of the light emitting element is connected to the second end of the third driving tube.

As a further improvement of an embodiment of the present invention, the material of the substrate of the third drive transistor includes single crystal silicon.

As a further improvement of an embodiment of the present invention, the pixel circuit further includes an on-off control circuit, the on-off control circuit is connected to the light-emitting element, configured to receive and control the on-off of the light-emitting element according to the on-off control signal off state.

As a further improvement of an embodiment of the present invention, the on-off control circuit is arranged between the light-emitting element and the parameter control circuit; the on-off control circuit includes a fourth switch tube, and the fourth switch tube The first terminal is connected to the negative pole of the light-emitting element, the second terminal of the fourth switch tube is connected to the current input terminal of the parameter control circuit, and the gate of the fourth switch tube is used to receive the on-off control signal .

As a further improvement of an embodiment of the present invention, the pixel circuit further includes a bias adjustment circuit, the bias adjustment circuit is arranged between the current output terminal of the parameter control circuit and the first node, and is configured to receive And according to the on-off control signal, the parameter control circuit is controlled to selectively set the light-emitting parameters of the light-emitting element; the on-off control signal is also used to control the on-off state of the light-emitting element.

As a further improvement of an embodiment of the present invention, the bias adjustment circuit includes a fifth switch tube, and the parameter control circuit includes a third drive tube and a storage capacitor; one end of the storage capacitor is connected to the third drive tube Gate to form the first node, the other end of the storage capacitor is connected to the ground level, and is connected to the first end of the third drive transistor through the fifth switch transistor, and the third drive transistor The second terminal is connected to the light-emitting element and the power supply level.

In order to achieve one of the objectives of the above invention, an embodiment of the present invention provides a pixel circuit driving method for driving the above pixel circuit, the pixel circuit driving method includes: controlling the first switching tube and the second switching tube At the same time, it is turned on, and the luminous parameter information is written into the parameter input terminal; the luminous element is driven and controlled to emit light in response to the luminous parameter information.

As a further improvement of an embodiment of the present invention, the pixel circuit further includes an on-off control circuit configured to receive and control the on-off state of the light-emitting element according to the on-off control signal; the method specifically The method includes: inputting the on-off control signal to the on-off control circuit, and controlling the light-emitting element to emit light in response to the light-emitting parameter information and the on-off control signal.

As a further improvement of an embodiment of the present invention, the method further includes: setting duty ratio data of the on-off control signal according to the light-emitting parameter information and brightness gray scale information.

As a further improvement of an embodiment of the present invention, the pixel circuit further includes a bias adjustment circuit configured to receive and control the parameter control circuit to selectively set the light emitting element according to the on-off control signal. Luminous parameters; the parameter control circuit includes a third drive tube; the method specifically includes: inputting the on-off control signal to the on-off control circuit and the bias adjustment circuit at the same time, controlling the third drive tube turn on, and control the light-emitting element to emit light in response to the light-emitting parameter information and the on-off control signal.

To achieve one of the objectives of the above invention, an embodiment of the present invention provides a display device, including the pixel circuit described in any one of the above technical solutions.

Compared with the prior art, the present invention sets two switch tubes connected in parallel between the first node for storing and maintaining the luminous parameter information and the parameter input terminal for receiving the luminous parameter information, and the two switches The tubes are turned on synchronously, which can stably receive luminous parameter information with a larger magnitude, especially when the luminous parameter information is in the form of voltage, it can make the pixel circuit enough to withstand the driving demand of higher voltage, so that the selection of the light-emitting element The range is wider, the adjustable range of brightness or other luminous parameters is wider, and based on this wider adjustable range, the pixel circuit is provided with a finer-grained gray scale adjustment capability.

Description of drawings

FIG. 1 is a circuit structural diagram of a pixel circuit in an embodiment of the present invention.

FIG. 2 is a circuit structure diagram of a pixel circuit in another embodiment of the present invention.

FIG. 3 is a schematic diagram of control timing of a pixel circuit in an embodiment of the present invention.

FIG. 4 is a schematic diagram of the control timing of the pixel circuit in another embodiment of the present invention.

FIG. 5 is a schematic diagram of steps of a method for driving a pixel circuit in an embodiment of the present invention.

Detailed ways

The present invention will be described in detail below in conjunction with specific embodiments shown in the accompanying drawings. However, these embodiments do not limit the present invention, and any structural, method, or functional changes made by those skilled in the art according to these embodiments are included in the protection scope of the present invention.

It should be noted that the term "comprising" or any other variation thereof is intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus comprising a set of elements includes not only those elements, but also items not expressly listed other elements, or also include elements inherent in such a process, method, article, or apparatus. Furthermore, the terms "first", "second", "third", "fourth", "fifth", etc. are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

The "switching tube" or "driving tube" used in any of the following embodiments provided by the present invention can preferably be realized by using a transistor. The transistors used for switching and driving functions can preferably be configured as thin film transistors (TFT, ThinFilm Transistor) and/or field effect transistors (FET, Field Effect Transistor). Both transistor types can be applied to the implementations provided below. In other words, each of the implementations provided below can form two parallel implementations based on the above two selections unless otherwise specified. . In addition, the field effect transistor may specifically include a junction field effect transistor (JFET, Junction FET) and a metal-oxide semiconductor field effect transistor (MOS-FET, Metal-Oxide Semiconductor FET).

Specifically, for a thin film transistor, the source and the drain are symmetrical, and the two are usually not distinguished, but the first terminal is used to replace one of the source and the drain, and the second terminal is used to replace the source and the drain. In the other, the gate of the thin film transistor can be used as a control terminal for receiving signal input from outside the thin film transistor. For field effect transistors, the connection mode of its source and drain has obvious directivity. Those skilled in the art can understand that, for the P-type field effect transistor, it can be connected to The source is connected to a higher level, and its drain is connected to a lower level; for N-type field effect transistors, its source can be connected to a lower level, and its drain to a higher level .

In addition, it is understandable that the embodiments provided below may not only include two parallel derivatives of thin film transistors and field effect transistors. Scenarios are also predictable. On the other hand, N-type transistors and P-type transistors in the circuit can also be replaced without considering special effects.

One embodiment of the present invention provides a display device, the display device includes a pixel circuit, under the action of the control circuit or other components inside the pixel circuit, the light-emitting elements used as pixels are driven according to the preset timing and The lighting parameter lights up, and the display operation is performed.

The display device may be provided in a TV, a watch and/or a computer. It can be seen that the display device does not only refer to the I/O device of the computer such as the monitor, which can independently form a complete electrical appliance such as a TV, or can be used as a part of other devices such as watches, refrigerators, smart speakers, laptops, etc. Play the role of output display.

One embodiment of the present invention provides a pixel circuit, which can be installed in any of the above-mentioned display devices or functional devices where the display devices are located, or can be installed on an independent substrate to form a separate driver chip for easy disassembly and assembly. .

As shown in FIG. 1 , in this embodiment, the pixel circuit includes a light emitting element 10 and a parameter control circuit 20 . Wherein, the light emitting element 10 is used to form a light emitting pixel in the pixel circuit. The present invention does not limit the specific type selection of the light emitting element 10. In one embodiment, the light emitting element 10 may be a sub-millimeter light emitting diode (Mini Light Emitting Diode, Mini LED for short), or may be a micro light emitting diode (Micro Light Emitting Diode). Emitting Diode, referred to as Micro LED), can also be an organic light emitting diode (OrganicLight Emitting Diode, referred to as OLED). In other words, the pixel circuit provided by the present invention also has the technical effect of being able to be applied to application scenarios such as submillimeter light-emitting diodes and/or micro light-emitting diodes, so that they can be driven normally and stably.

The parameter control circuit 20 can specifically be configured to receive the luminescence parameter information Data from the parameter input terminal 31, store the luminescence parameter information Data at the first node N1, and adjust at least one luminescence parameter of the light emitting element 10 according to the luminescence parameter information Data . The luminescence parameter information Data may be in the form of a voltage, so that in the parameter control circuit 20 , corresponding electronic components can be arranged to achieve the effect of storing the luminescence parameter information Data. Of course, in other embodiments of the present invention, the luminescence parameter information Data can also have other forms such as digital signals, so that the parameter control circuit 20 can adapt to different forms of luminescence parameter information Data to adjust the internal structure, such as adding digital-analog A converter (DAC, Digital-to-Analog Converter) and/or an analog-to-digital converter (ADC, Analog-to-Digital Converter), etc. Preferably, the luminous parameter information Data is used to adjust the brightness of the luminous element 10. Correspondingly, receiving the luminous parameter information Data corresponds to at least one luminous parameter of the luminous element 10 adjusted, which may be the highest brightness threshold of the luminous element 10 .

Preferably, a first switching transistor 41 and a second switching transistor 42 connected in parallel are further included between the parameter input terminal 31 and the first node N1. As mentioned above, the selection of the first switch tube 41 and the second switch tube 42 can be any one of field effect transistor and thin film transistor, and the former has the advantage of balancing cost and adapting to large current.

In one embodiment, the first switch tube 41 and the second switch tube 42 are configured to have opposite conduction conditions. Specifically, when the first end and the second end of the first switch tube 41 have the same or similar level as the first end and the second end of the second switch tube 42, the first switch tube 41 can be configured In order to be turned on when its control terminal (or gate, the same below) receives a high level, the second switch 42 can be configured to be turned on when its control terminal receives a low level.

On this basis, the pixel circuit can be correspondingly configured such that when the light emission parameter information Data is input to the parameter input terminal 31 , the first switch tube 41 and the second switch tube 42 are turned on simultaneously. In this way, the range of the light emission parameter information Data that is allowed to be stored in the parameter control circuit 20 can be expanded. Based on the wider allowable range of the luminous parameter information Data, the luminous element 10 can form a stepwise adjustment strategy with finer granularity and more quantity under a certain luminous parameter threshold pointed to by the luminous parameter information Data. For example, finer and more gray scales can be formed in terms of brightness. In addition, it can also meet the needs of more light-emitting elements 10 of different types, and improve the compatibility of the driving part of the pixel circuit.

Preferably, the first switch tube 41 can be a field effect tube, which can greatly reduce the overall cost of the circuit, and at the same time overcome limiting factors such as color accuracy, quality fluctuation, and depth of field caused by immature technology. In addition, the second switch tube 41 can also be configured as the same field effect tube as the first switch tube 41, and when the pixel circuit provided by the present invention is produced in batches, the beneficial effects brought about by saving cost and reducing process requirements , is not to be underestimated.

Based on this, the first switching transistor 41 can also be further configured as an N-type field effect transistor. Correspondingly, the second switching transistor 42 may also be further configured as a P-type field effect transistor. Therefore, the conduction characteristic of the field effect transistor can be used to effectively expand the range in which the two switch transistors receive the luminescence parameter information Data, so that the luminescence parameter information Data that can be accepted by the first node and the brightness adjustment range of the light emitting element 10 are expanded accordingly.

Understandably, the initialization control signals used to control the gate voltage of the first switch 41 and the gate voltage of the second switch 42 may be opposite. In one embodiment, the gate of the first switch 41 receives the first initialization signal Gate, the gate of the second switch 42 receives the second initialization signal GateR, the waveforms of the first initialization signal Gate and the second initialization signal Gate complementary. When the first initialization signal Gate is at high level, the second initialization signal GateR is at low level; when the first initialization signal Gate is at low level, the second initialization signal GateR is at high level.

An embodiment of the present invention provides an example of the circuit structure of the parameter control circuit 20. Of course, any device capable of receiving the luminous parameter information Data and adjusting the luminous parameter of the luminous element 10, such as a register, an integrated chip, etc., is included in the present invention. within the scope of protection. In this circuit structure example, the parameter control circuit 20 includes a third drive tube 23 and a storage capacitor 21 . Wherein, the storage capacitor 21 is used to hold the luminescence parameter information Data, especially the luminescence parameter information Data in the form of DC voltage. The third driving tube 23 is used for controlling the light emitting parameters of the light emitting element 10 according to the light emitting parameter information Data, and/or for driving and lighting the light emitting element 10 .

Preferably, the material of the substrate of the third driving transistor 23 includes single crystal silicon. In this way, the third drive tube 23 can have a strong driving capability, and can cooperate with the first switch tube 41 and the second switch tube 42 to provide a large current for the light-emitting element 10 and its branch or main circuit, so that the light-emitting element 10 can work in a high efficiency and stable interval (this is because the efficiency of light-emitting elements such as LEDs is proportional to the current density on it, and when the current density on it is within a certain range, the LED has a higher and stable work efficiency). And based on this, the third driving tube 23 can make the overall pixel circuit have the advantages of low power consumption and low temperature.

One end of the storage capacitor 21 is connected to the gate of the third driving transistor 23 to form a first node N1, and the other end of the storage capacitor 21 is connected to the first end 231 of the third driving transistor. In this way, the luminescence parameter information Data held in the storage capacitor 21 can be used to control the switching degree of the third drive tube 23 , thereby controlling the luminescence parameters of the light emitting element 10 such as the maximum turn-on brightness.

The definition of the first end 231 of the third drive tube can be adaptively adjusted according to the specific type selection of the third drive tube 23, for example, when the third drive tube 23 is a field effect tube, in particular, the third drive tube When 23 is an N-type field effect transistor, the first end 231 may specifically be the source of the third driving transistor 23 . Based on this, the luminescence parameter information Data can control the magnitude of the current flowing through the third drive tube 23 under the action of the storage capacitor 21 , so as to achieve the effect of stably controlling the luminescence parameters of the light emitting element 10 .

For example, if the gate-source voltage of the third drive tube 23 is defined as Vgs, and the threshold voltage of the third drive tube 23 is Vth, then the drain-source current of the third drive tube 23 is Ids at least satisfying:

Ids∝(Vgs-Vth) ² .

Furthermore, because the gate voltage of the third drive transistor 23 is affected by the luminescence parameter information Data, even in one embodiment, the gate voltage of the third drive transistor 23 is equal to the parameter voltage corresponding to the luminescence parameter information Data, so if the first The source voltage of the three driving tubes 23 is a constant value, then the drain-source current Ids of the third driving tube 23 directly depends on the luminous parameter information Data, thus, the luminous emission can be set for the luminous element 10 by adjusting the luminous parameter information Data. parameter.

Preferably, the first end 231 of the third driving transistor can be connected to the ground level VSS. Cooperating with the above-mentioned type selection, the light-emitting parameter information Data can be fully used to form the control of the light-emitting element 10, and other interferences can be excluded. Wherein, the ground level VSS can be embodied as a common ground terminal, or a negative pole of a power supply. Based on this, if it is defined that the gate voltage of the third drive tube 23 is stabilized at the parameter voltage Vdata by the light emission parameter information Data, then the drain-source current Ids on the third drive tube 23 at least satisfies:

Ids∝(Vdata-VSS-Vth) ² .

Preferably, the second terminal 232 of the third driving transistor is connected to the power supply level VDD. Wherein, the second end 232 of the third driving transistor can be specifically the drain of the third driving transistor 23 when the third driving transistor 23 is configured as an N-type field effect transistor, so that the drain-source current Ids is formed between the second end 232 of the third drive tube and the first end 231 of the third drive tube in a direction from the second end 232 to the first end 231 . The light-emitting element 10 can be correspondingly arranged on the main road where the drain-source current Ids is located, and is driven by the third driving tube 23 .

The light emitting element 10 can be connected in series between the first end 231 of the third driving transistor and the low level VSS. Preferably, the anode of the light emitting element 10 is connected to the power supply level VDD, and the cathode of the light emitting element 10 is connected to the second terminal 232 of the third driving transistor. In this way, the property of the third driving tube 23 can be adapted, so that the light emitting element 10 can be driven more stably.

It can be understood that words such as "connected" and "connected to" used in the description of the present invention do not only refer to direct connection, but may also be indirect connection in some embodiments. The indirect connection may be through some components in the circuit, or through one or more components.

In addition, after the first terminal 231 of the third driving transistor is connected to the ground level VSS, the current output terminal 201 of the parameter control circuit 20 can be formed. After the second terminal 232 of the third driving transistor is connected to the power supply level VDD, the current input terminal 202 of the parameter control circuit 20 can be formed.

In one embodiment, the pixel circuit may further include an on-off control circuit 50 for controlling the on-off state of the light-emitting element 10 according to a preset standard, especially the on-off period of the light-emitting element 10 . Preferably, the on-off control circuit 10 is connected to the light-emitting element 10 and configured to receive and control the on-off state of the light-emitting element 10 according to the on-off control signal EM. In this way, after the lighting parameter information Data sets the highest threshold for at least one lighting parameter of the light emitting element 10 , the on-off control circuit 50 can be used to implement a stepwise lighting strategy below the lighting parameter.

For example, even if the lighting parameter information Data sets the first threshold current I1 for the drain-source current Ids of the third driving transistor. In the limit state, assuming that between the non-luminous current I0 and the first threshold current I1, the light emitting element 10 can only work under the first threshold current I1, then the on-off control circuit 50 can be set to implement at least four conduction strategies . Specifically, the light-emitting element 10 may be controlled to turn on the first light-emitting time period T1, the second light-emitting time period T2, the third light-emitting time period T3, and the fourth light-emitting time period T4. If there is a double relationship between different light-emitting durations (for example, the first light-emitting duration T1 is twice the second light-emitting duration T2), the light-emitting element 10 can work at the first threshold current I1 and the non-light-emitting current I0. Therefore, the light-emitting element 10 can support the gray scale requirement of 16 bits under such extreme conditions. Based on this, the above structural configuration in the present invention expands the acceptable range of the light emission parameter information Data, and the corresponding pixel circuit can be configured to have a finer gray scale.

The on-off control signal EM can be specifically configured to have a PWM (Pulse Width Modulation, pulse width modulation) waveform, which can not only set the above-mentioned gray scale more accurately, but also can A large number of light emitting elements 10 are controlled in batches. Based on this, the pixel circuit can take into account both PWM driving and PAM (Pulse Amplitude Modulation, Pulse Amplitude Modulation) driving, and the latter can specifically be accomplished by using the light emitting parameter information Data and the parameter input terminal 31 . Therefore, the pixel circuit can have the advantages of the two driving modes at the same time.

The on-off control circuit 50 can be arranged at any position on the branch or main road where the light-emitting element 10 is located. The on-off control circuit 50 can be used to adjust the drain-source current Ids of the light-emitting element 10 selectively connected to the third driving transistor 23 . For example, the on-off control circuit 50 can be connected to the cathode side or the anode side of the light emitting element 10 , regardless of the connection relationship between the light emitting element 10 and the parameter control circuit 20 . Specifically, on the trunk road where the drain-source current Ids is located, the above three parts can be configured as “power supply level VDD—light emitting element 10—parameter control circuit 20—on-off control circuit 50—ground level VSS” The connection relationship can also be configured as the connection relationship of "power supply level VDD—parameter control circuit 20—light emitting element 10—on-off control circuit 50". To simplify the description, the present invention does not exhaustively describe it here.

Preferably, the on-off control circuit 50 can be arranged between the light-emitting element 10 and the parameter control circuit 20 to enhance the stability of the components.

Further, the on-off control circuit 50 may include a fourth switch tube 54, and use it to implement a switch function. The first terminal 541 of the fourth switching tube is connected to the negative pole of the light emitting element 10, the second terminal 542 of the fourth switching tube is connected to the current input terminal 202 of the parameter control circuit 20, and the gate of the fourth switching tube 54 is used to receive on-off control signal em. In this way, the stability of the driving of the light emitting element 10 and the timeliness of the modulation of the on-off control signal EM are ensured by using a simple arrangement of components.

Another embodiment of the present invention provides a pixel circuit, which can improve the working stability of the parameter control circuit 20 and prevent its internal components from being damaged.

In addition to including at least the aforementioned components such as the light emitting element 10 and the parameter control circuit 20, as shown in FIG. 2, the pixel circuit in this embodiment also includes a bias adjustment circuit 60, which is used to prevent the parameter control circuit 20 from continuously operating The resulting internal device damage.

Preferably, the bias adjustment circuit 60 may be disposed between the current output terminal 201 of the parameter control circuit 20 and the first node N1. Wherein, the current output terminal 201 can be interpreted as a terminal of the parameter control circuit 20 for connecting to the ground level VSS and outputting the current passing through the light emitting element 10 . Based on this, the start and stop of the parameter control circuit 20 can be affected by limiting the level of the current output terminal 201 .

Specifically, the bias adjustment circuit 60 may be configured to receive and control the parameter control circuit 20 to selectively set the light emission parameters of the light emitting element 10 according to the on-off control signal EM. Preferably, the on-off control signal EM is also used to control the on-off state of the light emitting element 10 . In this way, whether the operation of the parameter control circuit 20 is consistent with whether the light-emitting element 20 is turned on or not can prevent the parameter control circuit 20 from always operating when the light-emitting element 10 is turned off, causing its internal devices to always be in a biased state, thereby increasing the The overall stability and uniformity of the pixel circuit.

Preferably, in the embodiment where the parameter control circuit 20 includes the third drive transistor 23 and the storage capacitor 21 , the bias adjustment circuit 60 may specifically include a fifth switch transistor 65 to control whether the parameter control circuit 20 operates or not. Certainly, other switching devices may also be included in the bias adjustment circuit 60 alternatively.

For the parameter control circuit 20, one end of the storage capacitor 21 can be connected to the gate of the third drive transistor 23 to form the first node N1, and the other end of the storage capacitor 21 can be connected to the ground level VSS. The storage capacitor 21 can be connected to the first terminal 231 of the third driving transistor through the fifth switching transistor 56 . The second end 232 of the third driving transistor is connected to the light emitting element 10 and the power supply level VDD.

Under the action of the on-off control signal EM, if the fifth switch tube 65 is turned on, the level of the first end 231 of the third drive tube will be pulled down, and the first node N1 stores light-emitting parameter information Data, limiting the third The driving tube 23 is turned on and controls its drain-source current Ids according to the luminescence parameter information Data. If the fifth switching transistor 65 is turned off, the voltage difference between the first terminal 231 of the third driving transistor and its gate is smaller than its own threshold voltage, and the third driving transistor 23 is turned off.

Of course, in this embodiment, as shown in FIG. 2 , the pixel circuit can also be configured to include an on-off control circuit 50 . The on-off control circuit 50 preferably includes a fourth switch tube 54 . Since the fourth switching tube 54 is also controlled by the on-off control signal EM, the fourth switching tube 54 and the fifth switching tube 65 are turned on or off synchronously, so that the third driving Tube 23 is not always biased.

Although not described above, those skilled in the art can understand that, in some special application scenarios, the switching transistor or driving transistor mentioned above can of course be replaced by a thin film transistor. In other implementation manners, the above switching tube may also be configured as a switch or a linkage switch, or may be configured as a component such as an optocoupler relay.

FIG. 3 shows the working sequence of the pixel circuit in an implementation manner. In the first state, the first initialization signal Gate is set high, and the second initialization signal GateR is set low; in the second state, the recovery first initialization signal Gate is set low, the second initialization signal GateR is set high, and the modulated The on-off control signal EM is kept at a high level in the first period of time, which is the first light-emitting period T1. Before outputting the on-off control signal EM after pulse width adjustment to the on-off control circuit 50 and/or the bias adjustment circuit 60, it is necessary to simultaneously output the high-level first initialization signal Gate and the low-level second initialization signal Gate. Initialize the signal Gate. In each different time period, it is possible to adjust the duration of the on-off control signal EM to maintain a high level, such as the second lighting duration T2, the third lighting duration T3, the fourth lighting duration T4, etc., which are equal or different from each other. value. In a specific example, the relationship between the first light-emitting duration T1, the second light-emitting duration T2, the third light-emitting duration T3 and the fourth light-emitting duration T4 may be twice or ten times, for example, the first light-emitting duration T1 is If it is 1000ms, the second light-emitting duration T2 may be 100ms, so as to achieve high gray scale modulation.

FIG. 4 shows the working sequence of the pixel circuits in another implementation manner, and specifically configures the on-off control signals EM for controlling different pixel circuits to be different. For example, for the first pixel circuit, there is a first on-off control signal EM1, and for the second pixel circuit, there is a second on-off control signal EM2. In this way, when the pixel circuits provided by the present invention are configured in plural, by changing the on-off control signal EM, the light-emitting elements of different sizes can all work within a better efficiency range.

When EQE (External Quantum Efficiency, external quantum efficiency) is used to measure the working efficiency of the light-emitting element 10 , the light-emitting element 10 can have the largest EQE when the current density on the light-emitting element 10 is 5 A/cm ² . When the size of the light-emitting element in the first pixel circuit is 20×40 μm, the duty cycle of the first on-off control signal EM1 can be adjusted to 50%, so as to keep the light-emitting element having the maximum EQE. When the size of the light-emitting element in the second pixel circuit is 20×26 μm, the duty cycle of the second on-off control signal EM2 can be adjusted to 67%, so as to maintain the maximum EQE of the light-emitting element.

Of course, the above are only some examples to express the unique advantages of the present invention. When the indicator measuring the working efficiency of the light emitting element changes, and/or when the size of the light emitting element changes, the duty ratio of the on-off control signal EM can be adjusted accordingly.

In one embodiment, the present invention further provides a pixel circuit driving method based on the pixel circuit described in any one of the above technical solutions. As shown in FIG. 1 , FIG. 2 and FIG. 5 , the pixel circuit driving method includes the following steps.

Step 71 , control the first switch tube 41 and the second switch tube 42 to be turned on simultaneously, and write light emission parameter information Data to the parameter input terminal 31 .

Step 72, driving and controlling the light-emitting element 10 to emit light in response to the light-emitting parameter information Data.

In an embodiment where the pixel circuit includes an on-off control circuit 50, and the on-off control circuit 50 is configured to receive and control the on-off state of the light-emitting element 10 according to the on-off control signal EM, the step 72 may also specifically include the following steps described above.

Step 721, input the on-off control signal EM to the on-off control circuit 50, and control the light-emitting element 10 to emit light in response to the light-emitting parameter information Data and the on-off control signal EM.

In this way, PAM modulation and PWM modulation are realized at the same time.

Specifically, before the step 721, the following steps may also be included.

Step 720, according to the light emission parameter information Data and the brightness gray scale information, the duty ratio data of the on-off control signal EM is set.

Therefore, under the value such as the maximum luminance set by the luminescence parameter information Data, the luminescence parameter information Data can be segmented according to the required brightness grayscale information, so that it can be set to have the same or different duty in different periods. The ratio on-off control signal EM realizes the precise control of the gray scale of the light-emitting element 10 .

The pixel circuit includes a bias adjustment circuit 60, the bias adjustment circuit 60 is configured to receive and control the parameter control circuit 20 to selectively set the light emission parameters of the light emitting element 10 according to the on-off control signal EM, and the parameter control circuit 20 includes a second In the embodiment of the three driving tubes 23, the step 721 may specifically include the following steps.

Step 721', input the on-off control signal EM to the on-off control circuit 50 and the bias adjustment circuit 60 at the same time, control the third drive tube 23 to conduct, and control the light-emitting element 10 to emit light in response to the light-emitting parameter information Data and the on-off control signal EM .

To sum up, in the present invention, two switching tubes connected in parallel are arranged between the first node for storing and maintaining the lighting parameter information and the parameter input end for receiving the lighting parameter information, and the two switching tubes are turned on synchronously. , can stably receive luminous parameter information with a larger magnitude, especially under the condition that the luminous parameter information is in the form of voltage, it can make the pixel circuit enough to withstand the driving demand of higher voltage, and make the selection range of light-emitting elements wider. The adjustable range of brightness or other luminous parameters is wider, and based on this wider adjustable range, the pixel circuit is provided with a finer-grained gray scale adjustment capability.

It should be understood that although this description is described according to implementation modes, not each implementation mode only contains an independent technical solution, and this description in the description is only for clarity, and those skilled in the art should take the description as a whole, and each The technical solutions in the embodiments can also be properly combined to form other embodiments that can be understood by those skilled in the art.

The series of detailed descriptions listed above are only specific descriptions for feasible implementations of the present invention, and they are not intended to limit the protection scope of the present invention. Any equivalent implementation or implementation that does not depart from the technical spirit of the present invention All changes should be included within the protection scope of the present invention.

Claims (16)

1. A pixel circuit comprising a light emitting element and a parameter control circuit, the parameter control circuit being connected to the light emitting element and configured to receive light emitting parameter information from a parameter input, store it at a first node, and adjust at least one light emitting parameter of the light emitting element according to the light emitting parameter information;

the parameter input end and the first node comprise a first switching tube and a second switching tube which are mutually connected in parallel, and the conduction conditions of the first switching tube and the second switching tube are opposite; the pixel circuit is configured such that the first switching tube and the second switching tube are simultaneously turned on when the light emission parameter information is input to the parameter input terminal.

2. The pixel circuit of claim 1, wherein the first and second switching transistors are field effect transistors.

3. The pixel circuit of claim 2, wherein the first switching tube is an N-type field effect tube and the second switching tube is a P-type field effect tube.

4. The pixel circuit according to claim 1, wherein the parameter control circuit includes a third drive tube and a storage capacitor; one end of the storage capacitor is connected with the grid electrode of the third driving tube to form the first node, and the other end of the storage capacitor is connected to the first end of the third driving tube.

5. The pixel circuit according to claim 4, wherein a first end of the third driving tube is connected to a ground level, forming a current output end of the parameter control circuit; the second end of the third driving tube is connected to a power supply level to form a current input end of the parameter control circuit.

6. The pixel circuit according to claim 5, wherein a positive electrode of the light emitting element is connected to the power supply level, and a negative electrode of the light emitting element is connected to the second end of the third driving tube.

7. The pixel circuit of claim 4, wherein the material of the substrate of the third drive tube comprises monocrystalline silicon.

8. The pixel circuit of claim 1, further comprising an on-off control circuit coupled to the light emitting element configured to receive and control an on-off state of the light emitting element in accordance with an on-off control signal.

9. The pixel circuit according to claim 8, wherein the on-off control circuit is provided between the light emitting element and the parameter control circuit; the on-off control circuit comprises a fourth switching tube, a first end of the fourth switching tube is connected with the negative electrode of the light-emitting element, a second end of the fourth switching tube is connected with the current input end of the parameter control circuit, and a grid electrode of the fourth switching tube is used for receiving the on-off control signal.

10. The pixel circuit of claim 1, further comprising a bias adjustment circuit disposed between the current output of the parameter control circuit and the first node, configured to receive and control the parameter control circuit to selectively set the light emitting parameters of the light emitting element according to an on-off control signal; the on-off control signal is also used for controlling the on-off state of the light-emitting element.

11. The pixel circuit according to claim 10, wherein the bias adjustment circuit includes a fifth switching transistor, and the parameter control circuit includes a third driving transistor and a storage capacitor;

one end of the storage capacitor is connected with the grid electrode of the third driving tube to form the first node, the other end of the storage capacitor is connected with a ground level and is connected to the first end of the third driving tube through the fifth switching tube, and the second end of the third driving tube is connected to the light-emitting element and the power supply level.

12. A pixel circuit driving method for driving the pixel circuit of claim 1, comprising:

controlling the first switching tube and the second switching tube to be simultaneously conducted, and writing the luminous parameter information into the parameter input end;

the light emitting element is driven and controlled to emit light in response to the light emitting parameter information.

13. The method of driving a pixel circuit according to claim 12, wherein the pixel circuit further comprises an on-off control circuit configured to receive and control an on-off state of the light emitting element according to an on-off control signal; the method specifically comprises the following steps:

and inputting the on-off control signal to the on-off control circuit, and controlling the light-emitting element to emit light in response to the light-emitting parameter information and the on-off control signal.

14. The pixel circuit driving method according to claim 13, wherein the method further comprises:

and setting the duty ratio data of the on-off control signal according to the luminous parameter information and the brightness gray scale information.

15. The method according to claim 13, wherein the pixel circuit further comprises a bias adjustment circuit configured to receive and control the parameter control circuit to selectively set the light emission parameter of the light emitting element according to an on-off control signal; the parameter control circuit comprises a third driving tube; the method specifically comprises the following steps:

and simultaneously, the on-off control signal is input to the on-off control circuit and the bias adjustment circuit, the third driving tube is controlled to be conducted, and the light-emitting element is controlled to emit light in response to the light-emitting parameter information and the on-off control signal.

16. A display device comprising the pixel circuit according to any one of claims 1 to 11.

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