Pixel circuit and driving method thereof, display panel and display device thereof

Abstract

The embodiment of the invention provides a pixel circuit, a driving method of the pixel circuit, a display panel and a display device of the display panel, relates to the technical field of display, and aims to improve the display effect. The pixel circuit is configured to control the light emitting time of the light emitting device in response to a frequency sweep signal received at the frequency sweep signal end. The sweep frequency signal comprises a first stage and a second stage, and in the first stage, the sweep frequency signal continuously changes. In the second stage, the sweep frequency signal changes in a stepped mode. The pixel circuit is configured to control the light-emitting device to stop emitting light in response to the first target voltage of the sweep frequency signal of the first stage under the condition that the light-emitting device displays a relatively low gray scale. And controlling the light-emitting device to stop emitting light in response to a second target voltage of the sweep frequency signal of the second stage under the condition that the light-emitting device displays a relatively high gray scale. The second target voltage is the voltage of the sweep frequency signal at the starting point after the stepped change. The pixel circuit is used for the display panel.

Description

Technical Field

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

[0002] With the development of display technology, display devices have gradually become ubiquitous in people's lives. Among them, full-color display devices are widely used in smart products such as mobile phones, televisions, and laptops because they provide users with a better user experience.

[0003] In related technologies, display panels of display devices typically use red, green, and blue sub-pixels, and achieve full-color display by controlling grayscale and mixing them into any other color. However, during the display process, sub-pixels can experience color drift, leading to color shift in the displayed image and a decrease in display quality; or, local dark or bright spots may appear in the displayed image, resulting in poor brightness uniformity. Summary of the Invention

[0004] The purpose of the embodiments disclosed herein is to provide a pixel circuit and its driving method, a display panel and its display device, so as to improve the display effect.

[0005] To achieve the above objectives, the embodiments of this disclosure provide the following technical solutions:

[0006] On one hand, a pixel circuit is provided. The pixel circuit is used to connect to a light-emitting device. The pixel circuit is coupled to a sweep frequency signal terminal, and the pixel circuit is configured to control the light-emitting time of the light-emitting device in response to a sweep frequency signal received at the sweep frequency signal terminal. The sweep frequency signal includes a first stage and a second stage, wherein in the first stage, the sweep frequency signal changes continuously, and in the second stage, the sweep frequency signal changes in a stepped manner.

[0007] The pixel circuit is configured to, when the light-emitting device displays a lower grayscale, control the light-emitting device to stop emitting light in response to a first target voltage of the sweep frequency signal of the first stage; and, when the light-emitting device displays a higher grayscale, control the light-emitting device to stop emitting light in response to a second target voltage of the sweep frequency signal of the second stage. The second target voltage is the voltage at the starting point of the sweep frequency signal after a stepwise change.

[0008] In the pixel circuit provided in this embodiment, when the light-emitting device displays a lower grayscale, the pixel circuit responds to the sweep frequency signal of the first stage and controls the light-emitting device to stop emitting light, which can improve the brightness uniformity of the sub-pixels at low grayscale, thereby improving the display effect. Furthermore, when the light-emitting device displays a higher grayscale, the pixel circuit responds to the second target voltage of the sweep frequency signal of the second stage and controls the light-emitting device to stop emitting light, which can improve the color shift of the sub-pixels at high grayscale, thereby improving the display effect.

[0009] In some embodiments, the voltage of the sweep signal remains unchanged during the time period corresponding to any step of the second stage.

[0010] In some embodiments, during the first stage, the slope of the sweep signal remains constant or gradually increases in the direction from the first stage to the second stage.

[0011] In some embodiments, during the first stage, the frequency sweep signal is a smooth curve; the smooth curve refers to a curve whose slope changes continuously without interruption.

[0012] In some embodiments, the first stage comprises a plurality of consecutive segments, the sweep signal having a constant slope in each segment, and the slope of the sweep signal in segments relatively closer to the second stage being greater than the slope of the sweep signal in segments relatively farther from the second stage. The first target voltage is the voltage at the end point of one of the segments.

[0013] In some embodiments, the pixel circuit includes a pulse width modulation (PWM) module and a pulse amplitude modulation (PWM) module. The PWM module is coupled to the sweep frequency signal terminal, a first voltage signal terminal, a first node, and a second node, with the first node coupled to the data signal terminal. The PWM module is configured to, in the first stage when the light-emitting device displays a low grayscale, transmit a first voltage signal from the first voltage signal terminal to the second node in response to the sweep frequency signal from the sweep frequency signal terminal and the data signal written by the first node. In the second stage when the light-emitting device displays a high grayscale, transmit the first voltage signal from the first voltage signal terminal to the second node in response to the sweep frequency signal from the sweep frequency signal terminal and the data signal written by the first node.

[0014] The pulse amplitude modulation module is coupled to the second node, the third node, and the fourth node. The third node is coupled to a first power signal terminal, and the fourth node is coupled to a light-emitting device. The pulse amplitude modulation module is configured to, in the first stage when the light-emitting device displays a low grayscale, control the light-emitting device to stop emitting light in response to the voltage of the second node. In the second stage when the light-emitting device displays a high grayscale, control the light-emitting device to stop emitting light in response to the voltage of the second node.

[0015] In some embodiments, the data signal includes a plurality of higher grayscale data signals, and the voltage difference between two adjacent higher grayscale data signals is equal to the maximum voltage difference of at least one stepwise change in the swept frequency signal.

[0016] In some embodiments, the pulse width modulation module includes a first capacitor and a first transistor. The first capacitor includes a first plate and a second plate. The first plate is connected to the sweep frequency signal terminal, and the second plate is connected to the first node. The first electrode of the first transistor is coupled to the first voltage signal terminal, the second electrode is coupled to the second node, and the control electrode is connected to the first node; the first transistor is a P-type transistor. The sweep frequency signal exhibits a decreasing trend.

[0017] On the other hand, a driving method for a pixel circuit is provided. The driving method is applied to a pixel circuit as described in any of the above embodiments. The frequency sweep signal includes a first stage and a second stage. In the first stage, the frequency sweep signal changes continuously. In the second stage, the frequency sweep signal changes in a stepwise manner. The driving method includes:

[0018] When the light-emitting device displays a low grayscale, the pixel circuit responds to the first target voltage of the sweep frequency signal in the first stage and controls the light-emitting device to stop emitting light.

[0019] When the light-emitting device displays a higher grayscale, the pixel circuit, in response to the second target voltage of the second-stage sweep signal, controls the light-emitting device to stop emitting light. The second target voltage is the voltage at the starting point of the sweep signal after the stepwise change.

[0020] In another aspect, a display panel is provided. The display panel includes the pixel circuitry described in any of the above embodiments.

[0021] In another aspect, a display device is provided. The display device includes a display panel as described in the above embodiments.

[0022] The driving method, display panel, and display device of the pixel circuit described above have the same structure and beneficial technical effects as the pixel circuits provided in some of the above embodiments, and will not be repeated here. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in this disclosure, the accompanying drawings used in some embodiments of this disclosure will be briefly described below. Obviously, the drawings described below are only drawings of some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings. In addition, the drawings described below can be regarded as schematic diagrams.

[0024] Figure 1 This is a schematic diagram of the structure of a display device according to some embodiments;

[0025] Figure 2 This is a schematic diagram of the structure of another display device according to some embodiments;

[0026] Figure 3 This is a block diagram of a display device according to some embodiments;

[0027] Figure 4 This is a schematic diagram of the structure of a display panel according to some embodiments;

[0028] Figure 5 A circuit diagram of a sub-pixel according to some embodiments;

[0029] Figure 6 A timing diagram of a sweep frequency signal according to some embodiments;

[0030] Figure 7 This is a graph showing the relationship between brightness and time at low grayscale levels according to some embodiments;

[0031] Figure 8 This is a graph showing the relationship between brightness and time at high grayscale levels according to some embodiments;

[0032] Figure 9 A timing diagram of another sweep frequency signal according to some embodiments;

[0033] Figure 10 A timing diagram of yet another sweep frequency signal according to some embodiments;

[0034] Figure 11 This is a timing diagram of another sweep frequency signal according to some embodiments. Detailed Implementation

[0035] The technical solutions in some embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments provided in this disclosure are within the scope of protection of this disclosure.

[0036] Unless the context otherwise requires, throughout the specification and claims, the term "comprising" is interpreted as open-ended and encompassing, meaning "including, but not limited to." In the description of the specification, terms such as "one embodiment," "some embodiments," "exemplary embodiment," "example," or "some examples" are intended to indicate that a particular feature, structure, material, or characteristic associated with that embodiment or example is included in at least one embodiment or example of this disclosure. The illustrative representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics mentioned may be included in any suitable manner in any one or more embodiments or examples.

[0037] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of this disclosure, unless otherwise stated, "a plurality of" means two or more.

[0038] The terms "coupled" and "connected," and their derivatives, may be used in describing some embodiments. For example, the term "connected" may be used in describing some embodiments to indicate that two or more components have direct physical or electrical contact with each other. Similarly, the term "coupled" may be used in describing some embodiments to indicate that two or more components have direct physical or electrical contact. However, the term "coupled" may also refer to two or more components that do not have direct contact with each other but still cooperate or interact with each other. The embodiments disclosed herein are not necessarily limited to the content of this document.

[0039] "At least one of A, B and C" has the same meaning as "at least one of A, B or C", both including the following combinations of A, B and C: only A, only B, only C, combinations of A and B, combinations of A and C, combinations of B and C, and combinations of A, B and C.

[0040] "A and / or B" includes the following three combinations: A only, B only, and a combination of A and B.

[0041] The use of “configured as” in this article implies an open and inclusive language that does not exclude the applicability to or configuration of devices to perform additional tasks or steps.

[0042] As used herein, “equal” includes the described situation and situations that are similar to the described situation, within an acceptable range of deviation, which is determined by those skilled in the art taking into account the measurement under discussion and the error associated with the measurement of the particular quantity (i.e., the limitations of the measurement system). For example, “equal” includes absolute equality and approximate equality, wherein an acceptable range of deviation for approximate equality may be, for example, a difference between the two equal entities being less than or equal to 5% of either one.

[0043] In this disclosure, terms such as “down,” “below,” “above,” and “up” are used to explain the relationships between components shown in the accompanying drawings. The terms may be relative concepts and described based on the directions shown in the drawings, or based on the sequence of process steps, but are not limited thereto.

[0044] It should be understood that when a layer or element is referred to as being on another layer or substrate, it can mean that the layer or element is directly on another layer or substrate, or that there is an intermediate layer between the layer or element and another layer or substrate.

[0045] This document describes exemplary embodiments with reference to plan views as idealized exemplary drawings. In the drawings, the thickness of layers and the area of ​​regions are enlarged for clarity. Therefore, variations in shape relative to the drawings are contemplated due to, for example, manufacturing techniques and / or tolerances. Thus, exemplary embodiments should not be construed as limited to the shapes of the regions shown herein, but rather include shape deviations due to, for example, manufacturing processes. For example, etched areas shown as rectangular would typically have curved features. Therefore, the regions shown in the drawings are schematic in nature, and their shapes are not intended to show the actual shapes of areas of the device, nor are they intended to limit the scope of the exemplary embodiments.

[0046] In this disclosure, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0047] In the circuits provided in the embodiments of this disclosure, the first node, the second node, and the third node do not represent actual existing components, but rather represent the junctions of related electrical connections in the circuit diagram. In other words, these nodes are equivalent to the junctions of related electrical connections in the circuit diagram.

[0048] like Figure 1As shown, some embodiments of this disclosure provide a display device 1000, which can be any device that displays images, whether moving (e.g., video) or fixed (e.g., still images) and whether it is text or images.

[0049] For example, see Figure 1 and Figure 2 The display device 1000 can be any product or component with display function, such as electronic billboards, shopping mall displays, signs, televisions, computers, in-flight displays, vehicle displays, clocks, virtual reality (VR) devices, augmented reality (AR) devices, etc.

[0050] Depending on the application scenario, the display device 1000 can be a flat display device or a curved display device, and the shape of the display surface of the display device 1000 can be any one of a circle, an ellipse, a polygon, or an irregular shape.

[0051] For example, such as Figure 1 As shown, the display device 1000 can be a flat panel display device; for example, the display device 1000 can be... Figure 1 The electronic billboard shown. For example, such as... Figure 2 As shown, the display device 1000 can be a curved display device; for example, the display device 1000 can be... Figure 2 The wave-shaped curved surface display device shown.

[0052] In some embodiments, see Figure 1 and Figure 3 The display device 1000 may include one or more display panels 100. The number of display panels 100 can be set as needed. Figure 1 and Figure 2 The following example uses four display panels 100 as an illustration.

[0053] The display panel 100 described above includes various types, which can be selected and set according to actual needs. For example, the display panel 100 can be: an organic light-emitting diode (OLED) display panel, a quantum dot light-emitting diode (QLED) display panel, a micro light-emitting diode (Micro LED) display panel, a mini light-emitting diode (Mini LED) display panel, etc., and the embodiments disclosed herein are not limited to these.

[0054] In addition, see Figure 3 The display device 1000 may further include a host 200, with the display panel 100 connected to the host 200. The host 200 controls the display panel 100 to display content, enabling functions such as video splicing and synchronized playback. The host 200 may be an electronic device such as a TV box, server, mobile phone, or tablet, and the embodiments disclosed herein are not limited to these.

[0055] When the display device 1000 includes multiple display panels 100, each display panel 100 can display a portion of the image when displaying an image. The images displayed by each display panel 100 can be stitched together to form the complete content of the image, thereby achieving a larger screen effect and providing users with a better visual experience.

[0056] In some embodiments, the display device 1000 further includes a circuit board connected to a display panel 100. The host computer 200 can be connected to the circuit board to control the circuit board to provide display signals to the display panel 100. The circuit board can be disposed on the non-display side of the display panel 100 or integrated into the host computer 200; however, this embodiment is not limited to these options.

[0057] It should be noted that the circuit board may include a timing controller (TCON), a power management chip (DC / DC), and an adjustable resistor voltage divider circuit (generating Vcom), among other drive circuits.

[0058] In some embodiments, see Figure 4 The display panel 100 has a display area A and a peripheral area B disposed on at least one side of the display area A. Figure 4 The diagram illustrates the arrangement of the surrounding area B around the display area A.

[0059] The display area A is the area for displaying images, and it is configured to have multiple sub-pixels P. Each sub-pixel P can be understood as the smallest light-emitting unit in the display panel 100. The peripheral area B is the area where images are not displayed and is configured for circuit wiring, etc.

[0060] For example, such as Figure 4 As shown, display area A is provided with multiple sub-pixels P, which are arranged in multiple rows and columns. Each row includes at least two sub-pixels P arranged along the first direction X, and each column includes at least two sub-pixels P arranged along the second direction Y.

[0061] It should be noted that the first direction X is the row direction of the arrangement of multiple sub-pixels P, and the second direction Y is the column direction of the arrangement of multiple sub-pixels P. The first direction X and the second direction Y intersect; for example, the first direction X and the second direction Y are perpendicular.

[0062] Among them, see Figure 4 Multiple sub-pixels P can include various sub-pixels P with different emission colors to achieve full-color display. For example, multiple sub-pixels P include a first sub-pixel R, a second sub-pixel G, and a third sub-pixel B, where the emission colors of the first sub-pixel R, the second sub-pixel G, and the third sub-pixel B are the three primary colors; for example, the emission color of the first sub-pixel R is red, the emission color of the second sub-pixel G is green, and the emission color of the third sub-pixel B is blue.

[0063] Based on this, such as Figure 4 As shown, the arrangement of the first sub-pixel R, the second sub-pixel G, and the third sub-pixel B is not unique. For example, along the first direction X, a row of sub-pixels P is arranged cyclically in the order of the first sub-pixel R, the second sub-pixel G, and the third sub-pixel B, forming a standard RGB arrangement.

[0064] The following uses the standard RGB arrangement of the first sub-pixel R, the second sub-pixel G, and the third sub-pixel B as an example to illustrate some embodiments of this disclosure. However, the implementation of this disclosure is not limited to this, and any other arrangement can be considered as long as the same technical concept is applied.

[0065] See Figure 4 and Figure 5 The sub-pixel P includes a pixel circuit 10 and a light-emitting device 20. The pixel circuit 10 is connected to the light-emitting device 20 to drive the light-emitting device 20 to emit light.

[0066] The pixel circuit 10 is coupled to the sweep frequency signal terminal S. The pixel circuit 10 is configured to control the light emission time of the light-emitting device 20 in response to the sweep frequency signal received at the sweep frequency signal terminal S, so as to adjust the gray level of each sub-pixel P and make the sub-pixel P display at different gray levels.

[0067] In some embodiments, such as Figure 4 and Figure 5 As shown, the display panel 100 may also include a sweep frequency signal line 30, which is connected to the sweep frequency signal terminal S of the pixel circuit 10 of all sub-pixels P. The sweep frequency signal line 30 may be connected to a circuit board to transmit the sweep frequency signal provided by the circuit board to the pixel circuit 10 of each sub-pixel P, thereby controlling the light emission time of the light-emitting device 20 of each sub-pixel P.

[0068] The inventors discovered that in the display panels of the related technologies, when displaying at higher grayscale levels, subpixels will experience color drift, resulting in color deviation in the displayed image; or, when displaying at lower grayscale levels, there will be local dark spots or bright spots in the displayed image, resulting in poor brightness uniformity of the displayed image.

[0069] Based on this, see Figure 5 and Figure 6 In some embodiments of the present disclosure, the pixel circuit 10 includes a first stage P1 and a second stage P2. In the first stage P1, the sweep signal changes continuously, and in the second stage P2, the sweep signal changes stepwise.

[0070] The continuous change of the sweep frequency signal mentioned above refers to the time point when the voltage of the sweep frequency signal does not change abruptly, that is, the voltage of the sweep frequency signal gradually increases or gradually decreases.

[0071] The aforementioned stepwise change in the frequency sweep signal refers to the time points when the voltage of the frequency sweep signal undergoes abrupt changes. That is, the time points when the voltage of the frequency sweep signal undergoes abrupt increases or decreases. These time points are the time points when the light-emitting device 20 corresponding to a gray level stops emitting light, which is also the start or end point of the emitting time.

[0072] The pixel circuit 10 is configured to, when the light-emitting device 20 displays a lower grayscale, control the light-emitting device 20 to stop emitting light in response to a first target voltage of the sweep frequency signal of the first stage P1. Here, the first target voltage can be any time point on the sweep frequency signal of the first stage P1 (e.g., ...). Figure 6 and Figure 11 The voltage at point B1 in the image. For ease of description, the lower grayscale will be referred to as the low grayscale below.

[0073] At this time, when the light-emitting device 20 displays a low grayscale, the sweep frequency signal changes continuously, and the light-emitting device 20 can be slowly turned off at each low grayscale, so that the brightness of the low grayscale can be as expected, for example, as shown. Figure 7 As shown. Figure 7 The example uses two sub-pixels P, where the brightness of each sub-pixel P is the cumulative sum of the brightness at various points over time. In this case, different low grayscale levels require different times for the frequency sweep signal to change, such as... Figure 7The times t1 and t2 are used to obtain the corresponding brightness for different low gray levels, thus making the brightness of sub-pixel P accurate at different low gray levels.

[0074] It should be understood that when the light-emitting device 20 displays low grayscale, the voltage change between two adjacent low grayscales is small, and the sweep signal duration at low grayscales is very short. For example, at grayscale 10, the light-emitting time of the light-emitting device 20 is 10μs; at grayscale 3, the light-emitting time of the light-emitting device 20 is 1μs. Furthermore, since the sweep signal is transmitted synchronously to all pixel circuits 10, the load on the sweep signal is large. Therefore, the sweep signal cannot be precisely segmented according to the time interval between two adjacent low grayscales to accurately correspond to the voltage change time of the sweep signal when different low grayscales switch, thereby controlling the transistors in the pixel circuit 10 to respond quickly.

[0075] Based on this, when the light-emitting device 20 displays low grayscale, the sweep frequency signal changes continuously. Compared with the step-like change of the sweep frequency signal, this avoids the time node of the voltage change of the sweep frequency signal that cannot be accurately matched with each low grayscale, which causes the voltage of the sweep frequency signal received by the sub-pixel P to deviate. This causes the sub-pixel P to display abnormally in some low grayscale, resulting in the phenomenon of local dark spots or bright spots in the display screen.

[0076] Furthermore, the pixel circuit 10 is also configured to, when the light-emitting device 20 displays a higher grayscale, control the light-emitting device 20 to stop emitting light in response to a second target voltage of the sweep frequency signal of the second stage P2. The second target voltage is the starting point of the sweep frequency signal after a stepwise change (e.g., Figure 6 and Figure 11 The voltage at point A1 in the image. For ease of description, higher gray levels will be referred to as high gray levels below.

[0077] It should be noted that the low and high gray levels can be set according to actual conditions. For example, the brightness displayed by the light-emitting device 20 can be divided into 256 different levels from the darkest to the brightest, that is, the light-emitting device 20 has 0 to 255 gray levels, where 0 represents the darkest, 255 represents the whitest, and the values ​​in between represent different degrees of gray. In this case, the low gray level can be 0 to 64, and the high gray level can be 65 to 255. Of course, the embodiments disclosed in this disclosure are not limited to this, and the division of high and low gray levels can be specifically set according to the load of the sweep frequency signal and the display time of each gray level.

[0078] At this time, when the light-emitting device 20 displays a high grayscale, the sweep frequency signal changes in a step-like manner. The horizontal time interval of the step-like change is the light-emitting time interval of the light-emitting device 20 of adjacent grayscales. For example, the light-emitting time of the Mth grayscale is T1+…+Tm, where m is a positive integer; the light-emitting time of the Nth grayscale is T1+…+Tm+Tn, where n>m and is a positive integer. T1…Tn is the horizontal time interval of the step-like change.

[0079] It should be noted that the horizontal time interval of the step-like changes varies depending on the grayscale level. For example... Figure 6 The time interval between points A1 and A2 is not equal to the time interval between points A2 and A3.

[0080] In this way, at the time points of the stepwise change in the frequency sweep signal, the transistors in the pixel circuit 10 can be controlled to respond rapidly, thereby quickly turning off the light-emitting device 20, so that the brightness of the high grayscale can be as expected, for example... Figure 8 As shown. Figure 8 The following example uses two sub-pixels P. In this case, the time required for the frequency sweep signal to change varies for different high gray levels, such as... Figure 8 At times t3 and t4, different high gray levels can achieve corresponding brightness, and the brightness can drop rapidly at the cutoff times of t3 and t4, which helps to improve the color purity of sub-pixel P in high gray levels.

[0081] It should be understood that, due to the characteristics of the transistors in the pixel circuit 10, the transistors will turn on or off slowly, causing the light-emitting device 20 to slowly stop emitting light. During this stage, the sub-pixel P displays various other gray levels, causing the color point of the sub-pixel P to drift.

[0082] Based on this, when the light-emitting device 20 displays a high grayscale, the step-by-step change of the sweep frequency signal, compared with the continuous change of the sweep frequency signal, can shorten the time when the light-emitting device 20 slowly stops emitting light in the continuously changing sweep frequency signal, improve the shutdown tail of the light-emitting device 20, thereby reducing the influence of other grayscales displayed by the sub-pixel P in this stage, thereby improving the color point drift of the sub-pixel P and improving the color point purity of the sub-pixel P at high grayscale.

[0083] In summary, in the pixel circuit 10 provided in this embodiment, when the light-emitting device 20 displays a low grayscale, the pixel circuit 10 responds to the sweep frequency signal of the first stage P1 and controls the light-emitting device 20 to stop emitting light, which can improve the brightness uniformity of the sub-pixel P at low grayscale, thereby improving the display effect. Furthermore, when the light-emitting device 20 displays a high grayscale, the pixel circuit 10 responds to the second target voltage of the sweep frequency signal of the second stage P2 and controls the light-emitting device 20 to stop emitting light, which can improve the color shift of the sub-pixel P at high grayscale, thereby improving the display effect.

[0084] In some embodiments, see Figure 5 The pixel circuit 10 includes a pulse width modulation module 11 and a pulse amplitude modulation module 12.

[0085] like Figure 5 and Figure 6 As shown, the pulse width modulation module 11 is coupled to the sweep frequency signal terminal S, the first voltage signal terminal VH, the first node N1, and the second node N2. The first node N1 is coupled to the data signal terminal D. The pulse width modulation module 11 is configured such that, when the light-emitting device 20 displays a low grayscale, in a first stage P1, in response to the sweep frequency signal at the sweep frequency signal terminal S and the data signal written at the first node N1, the first voltage signal at the first voltage signal terminal VH is transmitted to the second node N2. When the light-emitting device 20 displays a higher grayscale, in a second stage P2, in response to the sweep frequency signal at the sweep frequency signal terminal S and the data signal written at the first node N1, the first voltage signal at the first voltage signal terminal VH is transmitted to the second node N2.

[0086] The first voltage signal terminal VH is configured to transmit a constant voltage signal, which can be a constant high voltage signal or a constant low voltage signal, depending on the actual circuit design. Here, we will illustrate the example of the first voltage signal terminal VH transmitting a constant high voltage signal.

[0087] The aforementioned data signal terminal D is configured to transmit data signals, which include multiple different grayscale data signals. These multiple different grayscale data signals include multiple high-grayscale data signals. The voltage difference between two adjacent higher-grayscale data signals is equal to the maximum voltage difference V1 of at least one step-like change in the frequency sweep signal (see...). Figure 6 and Figure 9 For example, the voltage difference between two adjacent higher grayscale data signals is equal to the maximum voltage difference V1 in a step-change pattern of the swept frequency signal.

[0088] It should be noted that the voltage difference between two adjacent higher gray levels varies depending on the gray level. For example... Figure 6 The maximum voltage difference between points A1 and A2 is not equal to the maximum voltage difference between points A2 and A3.

[0089] In this document, "high voltage" refers to the voltage that enables the N-type transistors to be turned on and the P-type transistors to be turned off; correspondingly, "low voltage" refers to the voltage that enables the N-type transistors to be turned off and the N-type transistors to be turned on.

[0090] For example, see Figure 5The pulse width modulation module 11 may include a first capacitor C and a first transistor T1. The first capacitor C includes a first plate and a second plate. The first plate is connected to the sweep frequency signal terminal S, and the second plate is connected to the first node N1. The first electrode of the first transistor T1 is coupled to the first voltage signal terminal VH, the second electrode is coupled to the second node N2, and the control electrode is connected to the first node N1.

[0091] Based on this, the first transistor T1 can be either a P-type transistor or an N-type transistor. When the first transistor T1 is a P-type transistor, the sweep frequency signal shows a decreasing trend. When the first transistor T1 is an N-type transistor, the sweep frequency signal shows an increasing trend.

[0092] In addition, see Figure 5 The pulse width modulation module 11 may further include a second transistor T2 and a third transistor T3. The second transistor T2 is coupled between the first electrode of the first transistor T1 and the first voltage signal terminal VH, and the third transistor T3 is coupled between the second electrode of the first transistor T1 and the second node N2. The control electrodes of the second transistor T2 and the third transistor T3 can be connected to the same control signal terminal EM, so as to work together with the first transistor T1 to control the conduction and cutoff between the first voltage signal terminal VH and the second node N2.

[0093] like Figure 5 and Figure 6 As shown, the pulse amplitude modulation module 12 is coupled to the second node N2, the third node N3, and the fourth node N4. The third node N3 is coupled to the first power supply signal terminal VDD, and the fourth node N4 is coupled to the light-emitting device 20. The pulse amplitude modulation module 12 is configured to, in the first stage P1, control the light-emitting device 20 to stop emitting light in response to the voltage of the second node N2 when the light-emitting device 20 displays a low grayscale. In the second stage P2, control the light-emitting device 20 to stop emitting light in response to the voltage of the second node N2 when the light-emitting device 20 displays a high grayscale.

[0094] For example, see Figure 5 The pulse amplitude modulation module 12 includes a fourth transistor T4. The first terminal of the fourth transistor T4 is coupled to the third node N3, the second terminal is coupled to the fourth node N4, and the control terminal is coupled to the second node N2. Based on this, the fourth transistor T4 can be either a P-type transistor or an N-type transistor.

[0095] It should be noted that the pixel circuit 10 may also include other circuit modules, such as a compensation module, etc., but specific examples are not given in this embodiment.

[0096] It should be understood that Figure 5The pixel circuit 10 may also include other transistors. Only some transistors are shown in this embodiment to illustrate the embodiment, but the embodiment is not limited thereto.

[0097] In the circuits provided in the embodiments of this disclosure, a constant high-voltage signal is transmitted through the first voltage signal terminal VH. P-type transistors are used as an example for illustration, but the embodiments of this disclosure include, but are not limited to, this. For example, one or more transistors in the circuits provided in the embodiments of this disclosure can also be N-type transistors. Simply connect the terminals of the selected type of transistor according to the terminals of the corresponding transistors in the embodiments of this disclosure, and provide the corresponding high or low voltage at the corresponding voltage terminals.

[0098] In some embodiments, see Figure 5 and Figure 6 At the start of the frequency sweep signal, the pixel circuit 10 is also configured to control the light-emitting device 20 to emit light. In this case, as the frequency sweep signal decreases, the sub-pixel P that first stops emitting light from the light-emitting device 20 has a lower grayscale. At this time, such as Figure 6 and Figure 9 As shown, the first stage P1 is located before the second stage P2.

[0099] In some embodiments, such as Figure 6 As shown, during any time period corresponding to step 40 in the second stage P2, the voltage of the sweep signal remains unchanged. This makes it easier for the voltage difference between grayscale data signals to correspond to the maximum voltage difference V1 of the step change of the sweep signal, and the sweep signal inputs a stable voltage at step 40, which is convenient for design.

[0100] In other embodiments, see Figure 9 During any time period corresponding to step 40 in the second stage P2, the voltage of the sweep signal gradually increases or decreases. For example, as... Figure 9 As shown, the sweep frequency signal exhibits a downward trend. At this time, during any time period corresponding to step 40 of the second stage P2, the voltage of the sweep frequency signal gradually decreases.

[0101] In this way, before controlling the corresponding light-emitting device 20 to stop emitting light, the sweep frequency signal can be gradually reduced to a lower voltage, and then the sweep frequency signal can be abruptly controlled to control the light-emitting device 20 to stop emitting light. This helps to further improve the response speed of the transistor, thereby shortening the time for the light-emitting device 20 to slowly stop emitting light and improving color deviation.

[0102] It should be noted that before controlling the corresponding light-emitting device 20 to stop emitting light, the sweep frequency signal can be gradually reduced to a lower voltage. This lower voltage will not cause the transistor in the pixel circuit 10 to change its on state.

[0103] In some embodiments, see Figure 6 , Figure 10 and Figure 11 In the first stage P1, the direction from the first stage P1 to the second stage P2, the slope of the frequency sweep signal remains unchanged or gradually increases, and the specific choice can be made flexibly according to the requirements.

[0104] For example, such as Figure 6 As shown, in the first stage P1, the slope of the sweep signal remains constant in the direction from the first stage P1 to the second stage P2. With this configuration, in the first stage P1, the voltage of the sweep signal changes over time as a sloping straight line, which is convenient for design.

[0105] For example, see Figure 10 and Figure 11 In the first stage P1, the slope of the sweep signal gradually increases from the first stage P1 to the second stage P2. By setting it in this way, in the first stage P1, as the grayscale increases, the response time of the transistors in the pixel circuit 10 can be reduced, thereby shortening the time it takes for the light-emitting device 20 to slowly emit light to the target brightness or slowly stop emitting light in the continuously changing sweep signal. This helps to improve the color purity of the sub-pixel P in low grayscale displays.

[0106] For example, such as Figure 10 As shown, in the first stage P1, the sweep frequency signal is a smooth curve. A smooth curve is defined as one whose slope changes continuously without interruption. For example, as... Figure 11 As shown, the first stage P1 includes multiple consecutive sub-segments P11. The slope of the sweep signal remains constant in each sub-segment P11, and the slope of the sweep signal in the sub-segments closer to the second stage P12 is greater than the slope of the sweep signal in the sub-segments farther from the second stage P12. At this time, the first target voltage is the termination point of a sub-segment P11 (e.g., Figure 11 The voltage at point B1 in the diagram.

[0107] The embodiments of this disclosure also provide a driving method for a pixel circuit 10, applied to the pixel circuit 10 of any of the above embodiments, the driving method including S100 to S200.

[0108] S100: When the light-emitting device 20 displays a lower grayscale, the pixel circuit 10 controls the light-emitting device 20 to stop emitting light in response to a first target voltage of the sweep frequency signal of the first stage P1. This first target voltage can be any time point on the sweep frequency signal of the first stage P1 (e.g., ...). Figure 6 and Figure 11 The voltage at point B1 in the diagram. See also... Figure 5 and Figure 6At the starting point of the frequency sweep signal, the pixel circuit 10 controls the light-emitting device 20 to emit light.

[0109] S200: When the light-emitting device 20 displays a higher grayscale, the pixel circuit 10, in response to the second target voltage of the sweep frequency signal of the second stage P2, controls the light-emitting device 20 to stop emitting light. This second target voltage is the voltage at the starting point of the sweep frequency signal after the stepwise change. See also... Figure 5 and Figure 6 At the starting point of the frequency sweep signal, the pixel circuit 10 controls the light-emitting device 20 to emit light.

[0110] The driving method for the pixel circuit 10 provided in this embodiment has the same structure and beneficial technical effects as the pixel circuit 10 provided in some of the above embodiments, and will not be described again here.

[0111] In the description of this specification, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0112] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A pixel circuit, characterized in that, Used to connect to a light-emitting device; the pixel circuit is coupled to a sweep frequency signal terminal, and the pixel circuit is configured to control the light-emitting time of the light-emitting device in response to a sweep frequency signal received at the sweep frequency signal terminal; The frequency sweep signal includes a first stage and a second stage. In the first stage, the frequency sweep signal changes continuously; in the second stage, the frequency sweep signal changes in a stepwise manner. The pixel circuit is configured to, when the light-emitting device displays a low grayscale, control the light-emitting device to stop emitting light in response to a first target voltage of the sweep frequency signal of the first stage; and, when the light-emitting device displays a high grayscale, control the light-emitting device to stop emitting light in response to a second target voltage of the sweep frequency signal of the second stage. The second target voltage is the voltage at the starting point of the frequency sweep signal after the stepwise change.

2. The pixel circuit according to claim 1, characterized in that, During any time period corresponding to any step in the second stage, the voltage of the sweep signal remains unchanged.

3. The pixel circuit according to claim 1, characterized in that, In the first stage, the slope of the sweep signal remains constant or gradually increases in the direction from the first stage to the second stage.

4. The pixel circuit according to claim 3, characterized in that, In the first stage, the frequency sweep signal is a smooth curve; the smooth curve refers to a curve whose slope changes continuously without interruption.

5. The pixel circuit according to claim 3, characterized in that, The first stage includes a series of consecutive sub-segments, the slope of the sweep signal remains constant in each sub-segment, and the slope of the sweep signal in the sub-segment closer to the second stage is greater than the slope of the sweep signal in the sub-segment farther from the second stage; the first target voltage is the voltage at the end point of one of the sub-segments.

6. The pixel circuit according to any one of claims 1 to 5, characterized in that, include: A pulse width modulation module is coupled to the frequency sweep signal terminal, the first voltage signal terminal, the first node, and the second node, with the first node coupled to the data signal terminal. The pulse width modulation module is configured to, in the first stage, transmit the first voltage signal of the first voltage signal terminal to the second node in response to the sweep frequency signal at the sweep frequency signal terminal and the data signal written by the first node when the light-emitting device displays a low grayscale. When the light-emitting device displays a high grayscale, in the second stage, in response to the sweep frequency signal at the sweep frequency signal terminal and the data signal written by the first node, the first voltage signal at the first voltage signal terminal is transmitted to the second node; A pulse amplitude modulation module is coupled to the second node, the third node, and the fourth node. The third node is coupled to a first power signal terminal, and the fourth node is coupled to a light-emitting device. The pulse amplitude modulation module is configured to, in the first stage when the light-emitting device displays a low grayscale, control the light-emitting device to stop emitting light in response to the voltage of the second node; and in the second stage when the light-emitting device displays a high grayscale, control the light-emitting device to stop emitting light in response to the voltage of the second node.

7. The pixel circuit according to claim 6, characterized in that, The data signal includes multiple higher grayscale data signals, and the voltage difference between two adjacent higher grayscale data signals is equal to the maximum voltage difference of at least one step change in the swept frequency signal.

8. The pixel circuit according to claim 6, characterized in that, The pulse width modulation module includes: The first capacitor includes a first plate and a second plate; the first plate is connected to the sweep frequency signal terminal, and the second plate is connected to the first node. The first transistor has a first electrode coupled to the first voltage signal terminal, a second electrode coupled to the second node, and a control electrode connected to the first node; the first transistor is a P-type transistor; the sweep frequency signal exhibits a decreasing trend.

9. A driving method for a pixel circuit, characterized in that, Applied to the pixel circuit as described in any one of claims 1 to 8, the sweep frequency signal includes a first stage and a second stage, wherein the sweep frequency signal changes continuously in the first stage; In the second stage, the frequency sweep signal changes in a stepwise manner; the driving method includes: When the light-emitting device displays a low grayscale, the pixel circuit responds to the first target voltage of the sweep frequency signal in the first stage and controls the light-emitting device to stop emitting light. When the light-emitting device displays a high grayscale, the pixel circuit responds to the second target voltage of the sweep frequency signal in the second stage and controls the light-emitting device to stop emitting light; the second target voltage is the voltage at the starting point of the sweep frequency signal after the step change.

10. A display panel, characterized in that, Includes the pixel circuit as described in any one of claims 1 to 8.

11. A display device, characterized in that, Includes the display panel as described in claim 10.

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