Pixel circuit driving method, display panel and display device

Abstract

The present invention discloses a driving method for a pixel circuit, a display panel and a display device. The driving method comprises: providing a light-emitting control signal to the pixel circuit, wherein in each display frame, the light-emitting control signal comprises at least two pulses with different duty cycles; in at least two display frames, the arrangement order of the pulses in the light-emitting control signal is different. The embodiment of the present invention can improve the flickering problem of the display panel in the full brightness display range under the low refresh frequency state.

Description

Technical Field

[0001] The present invention relates to the field of display technology, and in particular to a driving method for a pixel circuit, a display panel and a display device. Background Art

[0002] In the existing pixel circuit, in a display frame, due to leakage or characteristic drift of the driving transistor, the driving current generated by the driving transistor in the refresh frame and the hold frame is different, resulting in differences in the brightness of the light-emitting device, which in turn causes the display panel to flicker. Moreover, when the brightness of the light-emitting device is different, the flickering pattern is different, affecting the visual experience. Summary of the invention

[0003] The present invention provides a driving method for a pixel circuit, a display panel and a display device, so as to improve the flickering problem of the display panel in a full brightness display range under a low refresh frequency state.

[0004] To achieve the above technical objectives, the embodiments of the present invention provide the following technical solutions:

[0005] A method for driving a pixel circuit comprises: providing a light emitting control signal to the pixel circuit, wherein in each display frame, the light emitting control signal comprises at least two pulses with different duty cycles; and in at least two display frames, the arrangement order of the pulses in the light emitting control signal is different.

[0006] Optionally, in at least two display frames, pulses with different duty cycles in the light emitting control signal are arranged in different orders, including:

[0007] In multiple display frames, multiple light-emitting control signals are cyclically provided to the pixel circuit, wherein the duty cycles of at least two pulses in the same light-emitting control signal are different; the types and numbers of pulses in different light-emitting control signals are the same, but the arrangement order of the pulses is different.

[0008] Optionally, the arrangement order of the pulses in the light-emitting control signal is different, including: the light-emitting control signal includes at least two pulses with different duty cycles, and the at least two pulses with different duty cycles are randomly arranged.

[0009] Optionally, one of the display frames includes a refresh frame and a hold frame;

[0010] In the refresh frame, the light emitting control signal includes one pulse, and in the hold frame, the light emitting control signal includes at least two pulses with different duty cycles;

[0011] Preferably, in each refresh frame, the duty cycle of the pulses of the light emitting control signal is the same.

[0012] Optionally, one of the display frames includes a refresh frame and a hold frame;

[0013] In the refresh frame, the light control signal includes one pulse, and in the hold frame, the light control signal includes one pulse; in the same display frame, the duty cycle of the light control signal in the refresh frame is different from that in the hold frame.

[0014] Optionally, before providing the light emitting control signal to the pixel circuit, the method further includes:

[0015] Obtaining the target brightness of each display frame in the display frame sequence;

[0016] Based on the target brightness of each display frame, the arrangement order of the pulses in the light emitting control signal in each display frame is determined.

[0017] Optionally, when the target brightness is greater than the first brightness threshold, the duty cycle of each pulse of the light emitting control signal gradually decreases within the same display frame;

[0018] When the target brightness is less than the second brightness threshold, the duty cycle of each pulse of the light emitting control signal gradually increases within the same display frame;

[0019] The first brightness threshold is greater than or equal to the second brightness threshold.

[0020] Optionally, in each display frame, the light emitting control signal includes 3-8 pulses;

[0021] Preferably, in the same display frame, the duty cycle of each pulse in the light emitting control signal is different.

[0022] Accordingly, an embodiment of the present invention further provides a display panel, comprising: a pixel circuit and a light emitting control circuit; the pixel circuit comprises a light emitting module;

[0023] The output end of the light-emitting control circuit is connected to the light-emitting control signal line, and the pixel circuit is connected to the light-emitting control signal line. The light-emitting control circuit is used to generate a light-emitting control signal, and the light-emitting control signal controls the light-emitting duration of the light-emitting module in the pixel circuit within a display frame;

[0024] The light-emitting control circuit is used to output a light-emitting control signal to the light-emitting control signal line. In each display frame, the light-emitting control signal includes at least two pulses with different duty cycles. In at least two display frames, the arrangement order of the pulses in the light-emitting control signal is different.

[0025] Correspondingly, an embodiment of the present invention further provides a display device, comprising: a display panel provided by any embodiment of the present invention.

[0026] In the driving method of the pixel circuit provided by the embodiment of the present invention, by setting the light-emitting control signal in each display frame to include at least two pulses with different duty cycles, and changing the pulse sequence of the light-emitting control signal in different display frames, the pulse arrangement sequence of the light-emitting control signal in each display frame is set in a disordered manner, so that in different display frames, the light-emitting duration of each display subframe has different change rules, thereby being compatible with high-brightness and low-brightness display applications, increasing the probability of each brightness state matching a display frame with an optimized adjustment effect on the brightness change trend, maximizing the improvement of the display flicker problem in the full brightness range, facilitating the reduction of the refresh frequency of the display panel, providing conditions for the continuous reduction of product power consumption, and enhancing product competitiveness. Therefore, compared with the prior art, the embodiment of the present invention can improve the flicker problem of the display panel in the full brightness display range under the low refresh frequency state.

[0027] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 It is a structural schematic diagram of an existing pixel circuit;

[0030] Figure 2 It is a driving timing diagram of an existing pixel circuit;

[0031] Figure 3 is the change trend of the luminous brightness of the luminous module in the high-brightness display state;

[0032] Figure 4 is the change trend of the luminous brightness of the luminous module in the low-brightness display state;

[0033] Figure 5 is a waveform diagram of a light emitting control signal provided by an embodiment of the present invention;

[0034] Figure 6 is a schematic diagram of brightness change of the light-emitting module under the existing driving method;

[0035] Figure 7 is a schematic diagram of the flicker degree of the display panel under the existing driving method;

[0036] Figure 8 is a schematic diagram of brightness change of a light emitting module under a driving method provided in an embodiment of the present invention;

[0037] Fig. 9 is a schematic diagram of the flicker degree of the display panel under the driving method provided by an embodiment of the present invention;

[0038] Fig.10 is a waveform diagram of another light emitting control signal provided by an embodiment of the present invention;

[0039] Fig.11 is a waveform diagram of another light emitting control signal provided by an embodiment of the present invention;

[0040] Fig.12 is a schematic flow chart of a driving method for a pixel circuit provided by an embodiment of the present invention;

[0041] Fig.13 It is a schematic diagram of the structure of a display panel provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0042] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0043] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions.

[0044] As described in the background technology, the light emitting device in the pixel circuit has brightness difference in the refresh frame and the hold frame, and when the brightness is different, the brightness changes differently in a display frame, causing the display panel to flicker. The reasons for the above problems are described in detail below.

[0045] Figure 1 Schematic diagram of a conventional pixel circuit. Figure 1, the pixel circuit includes: a pixel driving circuit 11 and a light emitting module 12. Taking the pixel driving circuit of the 7T1C architecture as an example, illustratively, the pixel driving circuit 11 includes: a driving transistor M11, a transistor M12, a transistor M13, a transistor M14, a transistor M15, a transistor M16, a transistor M17 and a storage capacitor Cst. Among them, the gate of the transistor M14 and the gate of the transistor M17 can both be connected to the scanning signal S1, the gate of the transistor M12 and the gate of the transistor M13 can both be connected to the scanning signal S2, and the gate of the transistor M15 and the gate of the transistor M16 can both be connected to the light emitting control signal EM. The light emitting module 12 can be composed of a current-driven light emitting device OLED.

[0046] Figure 2 The present invention is a driving timing diagram of an existing pixel circuit. Figure 2 The driving timing for low-frequency display is given as an example. In the low-frequency refresh scenario, a display frame of the pixel circuit includes a refresh frame T1 and a hold frame T2, wherein the refresh frame T1 can be composed of a display subframe (refresh subframe), and the hold frame T2 can be composed of at least one display subframe (hold subframe). Specifically, the refresh subframe includes an initialization phase T11, a data writing phase T12, and a first light-emitting phase T13. The hold subframe includes a black insertion phase T21 and a second light-emitting phase T22. Combined with Figure 1 and Figure 2 , taking the case where all transistors in the pixel driving circuit 11 are P-type transistors as an example, the driving process of the pixel circuit includes:

[0047] In the initialization stage T11, the scanning signal S1 is at a low potential, and the scanning signal S2 and the light-emitting control signal EM are at a high potential. The transistors M14 and M17 are turned on, and the initialization voltage signal Vref is transmitted to the gate of the driving transistor M11 through the transistor M14 to initialize the gate of the driving transistor M11. In addition, the initialization voltage signal Vref is transmitted to the anode of the light-emitting device OLED through the transistor M17 to initialize the anode of the light-emitting device OLED.

[0048] In the data writing phase T52, the scanning signal S2 is at a low potential, the scanning signal S1 and the light emitting control signal EM are at a high potential, the transistor M12 and the transistor M13 are both turned on, and the data voltage Vdata is transmitted to the gate of the driving transistor M11 via the transistor M12, the driving transistor M11 and the transistor M13.

[0049] In the first light-emitting stage T13, the light-emitting control signal EM is at a low potential, and the scanning signal S1 and the scanning signal S2 are at a high potential. The transistor M15 and the transistor M16 are both turned on. The driving transistor M11 generates a driving current based on the first power signal VDD and the gate potential of the driving transistor M11 to drive the light-emitting device OLED to emit light.

[0050] In the black insertion stage T21, the light control signal EM, the scanning signal S1 and the scanning signal S2 are all at high potential. All transistors in the pixel driving circuit 11 are turned off. The connection path between the driving transistor M11 and the light emitting device OLED is disconnected, and the light emitting device OLED does not emit light.

[0051] In the second light-emitting stage T22, the light-emitting control signal EM is at a low potential, and the scanning signal S1 and the scanning signal S2 are at a high potential. The transistor M15 and the transistor M16 are both turned on. The driving transistor M11 generates a driving current based on the first power signal VDD and the potential stored in the gate of the driving transistor M11 in the refresh subframe to drive the light-emitting device OLED to emit light.

[0052] From the above analysis, it can be seen that in the driving process of the pixel circuit, data is written to the pixel driving circuit 11 in the refresh frame T1; and data is no longer written to the pixel driving circuit 11 in the holding frame T2. Based on the effect of the storage capacitor Cst maintaining the gate potential of the driving transistor M11, in each second light-emitting sub-stage T22 in the holding frame T2, the driving transistor M11 generates a driving current according to its gate potential to drive the light-emitting device OLED to emit light.

[0053] Ideally, after the data writing stage T12 is completed, the gate potential of the driving transistor M11 remains unchanged throughout the display frame, so that the driving current generated by the driving transistor M11 in each light-emitting stage remains unchanged, so that the light-emitting intensity of the light-emitting device OLED in each second light-emitting stage T22 is the same as that in the first light-emitting stage T13. However, in actual applications, if Figure 1 As shown, the gate of the driving transistor M11 has two leakage paths, namely, the transistor M13 and the transistor M14. The leakage causes the gate potential of the driving transistor M11 to change, so that the driving current generated by the driving transistor M11 in each light-emitting stage is different, so that the light-emitting intensity of the light-emitting device OLED in different light-emitting stages is different. The brightness finally reflected by the pixel circuit to the outside is positively correlated with the light-emitting intensity and light-emitting duration of the light-emitting device OLED. In the prior art, the frame time of each display subframe is the same, and the duty cycle of the light-emitting control signal EM in each display subframe is the same, that is, the duration of each light-emitting stage is the same. Then, due to the leakage, the light-emitting intensity of the light-emitting device OLED in each light-emitting stage is different, so that the light-emitting brightness between the second light-emitting stage T22 and the first light-emitting stage T13, and between different second light-emitting stages T22 are different, causing the flickering of the display panel.

[0054] Under different brightness, due to the different leakage paths of the driving transistor M11, the brightness change trend in a display frame is different. The specific analysis is as follows:

[0055] When displaying at high brightness, the potential of the data voltage Vdata is low, so that the driving transistor M11 generates a larger driving current, driving the light-emitting device OLED to emit light with a greater luminous intensity. In this state, the gate of the driving transistor M11 leaks through the transistor M13. At this time, the first pole of the driving transistor M11 is the high potential of the first power supply signal VDD. Since the conduction degree of the driving transistor M11 is high, the potential of the second pole of the driving transistor M11 is also high. Therefore, through the leakage path of the transistor M13, the gate potential of the driving transistor M11 will gradually increase, so that the driving current generated by the driving transistor M11 will gradually decrease, and thus the luminous intensity of the light-emitting device OLED will gradually decrease. The trend of brightness change is shown in Figure 2. Figure 3 As shown in , when high brightness is displayed, the brightness gradually decreases within one display frame.

[0056] When displaying at low brightness, the potential of the data voltage Vdata is high, so that the driving transistor M11 generates a smaller driving current, driving the light-emitting device OLED to emit light with a smaller luminous intensity. In this state, the gate of the driving transistor M11 leaks through the transistor M14. Since the initialization voltage signal Vref is a low potential signal, the gate potential of the driving transistor M11 gradually decreases through the leakage path of the transistor M14, thereby gradually increasing the driving current generated by the driving transistor M11, and then the luminous intensity of the light-emitting device OLED gradually increases. The change trend of brightness is shown in Figure 1. Figure 4 As shown in , when low brightness is displayed, the brightness gradually increases within one display frame.

[0057] In the prior art, in order to solve the flicker problem of the display panel, transistor M13 and transistor M14 are usually set as dual-gate transistors or N-type transistors from the perspective of suppressing leakage. The solution in the prior art can reduce the leakage of the gate of the driving transistor M11 to a certain extent, but it cannot completely prevent leakage, so the flicker problem still exists under low-frequency display. And under different brightness states, the brightness change trend within a display frame is different, and it is difficult for the prior art to achieve display adjustment for the full brightness range. On the other hand, the product refresh frequency is strongly related to the product power consumption. The higher the refresh frequency, the higher the product power consumption; the above-mentioned flicker problem is difficult to solve, making it difficult to achieve a low refresh rate for the product, and it also causes the product power consumption to reach a bottleneck, reducing the competitiveness of the product.

[0058] In order to solve the above problems, an embodiment of the present invention provides a driving method for a pixel circuit, which improves the flicker problem in the full brightness range at a low refresh rate based on the idea of ​​pulse duty cycle time domain jitter of a light emitting control signal. The driving method for the pixel circuit includes:

[0059] A light emitting control signal is provided to the pixel circuit. In each display frame, the light emitting control signal includes at least two pulses with different duty cycles. In at least two display frames, the pulses in the light emitting control signal are arranged in different orders.

[0060] Among them, a display frame may include multiple display subframes, each display subframe includes a pulse of the light-emitting control signal, and the duration of each display subframe is equal. The light-emitting control signal is a multi-pulse signal with alternating high and low potentials, and the pulse period of each pulse is the same, and the pulse period is equal to the duration of a display subframe. By controlling the duty cycle of the pulse of the light-emitting control signal, the light-emitting duration in each display subframe can be controlled. Exemplarily, when the light-emitting control signal is a conduction potential (e.g., a low potential), the light-emitting module in the pixel circuit emits light; when the light-emitting control signal is a cut-off potential (e.g., a high potential), the light-emitting module in the pixel circuit does not emit light. The duty cycle of the pulse of the light-emitting control signal can be understood as the proportion of the duration of the cut-off potential of the light-emitting control signal to the entire pulse period. When the duty cycle is small, the light-emitting duration of the light-emitting module in the display subframe is long; when the duty cycle is large, the light-emitting duration of the light-emitting module in the display subframe is short. In general, the pixel circuit controls the light-emitting duration of the light-emitting module in each display frame according to the light-emitting control signal.

[0061] The light-emitting control signal includes at least two pulses with different duty cycles, which can be understood as follows: the multiple pulses in the light-emitting control signal can be divided into multiple types of pulses according to whether the duty cycles are the same, and the duty cycles of different types of pulses are different. A display frame includes at least two types of pulses of the light-emitting control signal. The number of pulses of the same type and the arrangement order of each pulse can be set according to actual needs.

[0062] In at least two display frames, the arrangement order of pulses in the light control signal is different, which is equivalent to jittering the duty cycle of each pulse of the light control signal in the time domain, so that in at least two display frames, the light duration of each display subframe changes in a different pattern.

[0063] According to the above analysis of the background technology issues, the luminous brightness is positively correlated with the luminous intensity and luminous duration of the luminous module. Also, in a low refresh rate scenario, under different brightness states, such as high brightness and low brightness display, the leakage law of the driving transistor in a display frame is different, which makes the change trend of the luminous brightness under different brightness states inconsistent. Therefore, for different brightnesses, the adjustment direction of the luminous duration of each display subframe in the display frame is different. If the pulses of different duty cycles of the luminous control signal are arranged in the same order in each display frame, only the flicker problem under partial brightness can be improved, and the flicker problem within the full brightness range cannot be covered. For example, when the duty cycle of the luminous control signal in each display frame is reduced successively, the luminous duration of each display subframe in the display frame is increased successively, which can only alleviate the downward trend of the luminous intensity of the luminous module under high brightness, and cannot improve the flicker problem under low brightness.

[0064] In the embodiment of the present invention, from the perspective of adjusting the luminous duration, by disrupting the arrangement order of different duty cycle pulses of the luminous control signal in each display frame, the change trend of the luminous duration of each display subframe in different display frames can be adjusted, so that the change trend of the luminous brightness in at least two different display frames is different. The luminous duration of each display subframe in a display frame no longer presents a single change rule. In different display frames, the luminous duration of each display subframe can present any possible change trend such as increasing in sequence, decreasing in sequence, increasing first and then decreasing, or decreasing first and then increasing. In the actual display process, any brightness state can match any luminous duration change trend. Exemplarily, the change rule of the luminous duration in the display frame can be attributed to the following two categories: The characteristics of the first type of display frame are: the scope of application of the change rule of the luminous duration is small, but it can match the optimal adjustment effect of a certain brightness or a certain brightness range. For example, the luminous duration of each display subframe increases progressively, which is just opposite to the change trend of the luminous intensity of the luminous module in the high brightness state, and the optimal adjustment effect in the high brightness state can be achieved. The characteristics of the second type of display frame are: the applicable range of the variation law of the luminous duration is relatively wide. Although it cannot provide the optimal adjustment effect for a certain brightness or a certain brightness range, it can provide a certain effect of improving flicker in a wide brightness range. For example, the luminous duration of each display subframe does not change monotonically, and the variation law of the luminous duration is different from the variation trend of the luminous intensity of the luminous module in high and low brightness states, which has a certain improvement effect on flicker in high and low brightness states.

[0065] In short, in the display frame matched to the high brightness state, as long as there is at least one section of the trend of increasing the light emission duration, the flicker problem under high brightness can be alleviated to a certain extent; correspondingly, in the display frame matched to the low brightness state, as long as there is at least one section of the trend of decreasing the light emission duration, the flicker problem under low brightness can be alleviated to a certain extent. In this way, compared with the single duty cycle arrangement sequence of the pulses of the light emission control signal in each display frame, the probability of each brightness state matching the display frame that can improve the flicker can be increased, and the improvement effect of the flicker problem of the display panel can be improved.

[0066] In the driving method of the pixel circuit provided by the embodiment of the present invention, by setting the light-emitting control signal in each display frame to include at least two pulses with different duty cycles, and changing the pulse sequence of the light-emitting control signal in different display frames, the pulse arrangement sequence of the light-emitting control signal in each display frame is set in a disordered manner, so that in different display frames, the light-emitting duration of each display subframe has different change rules, thereby being compatible with high-brightness and low-brightness display applications, increasing the probability of each brightness state matching a display frame with an optimized adjustment effect on the brightness change trend, maximizing the improvement of the display flicker problem in the full brightness range, facilitating the reduction of the refresh frequency of the display panel, providing conditions for the continuous reduction of product power consumption, and enhancing product competitiveness. Therefore, compared with the prior art, the embodiment of the present invention can improve the flicker problem of the display panel in the full brightness display range under the low refresh frequency state.

[0067] On the basis of the above-mentioned embodiments, optionally, the light-emitting control signal required by each row of pixel circuits in the display panel can be provided by a cascade-connected multi-stage light-emitting control circuit, each stage of the light-emitting control circuit is connected to a row of pixel circuits, and the start signal required by the first stage of the light-emitting control circuit can be provided by the driver IC, and the light-emitting control signals of each stage are output by step-by-step shifting of the start signal. The driver IC can edit the waveform of the light-emitting control signal of each stage by editing the waveform of the start signal, that is, edit the arrangement sequence of the light-emitting control signal pulse. In practical application, the driver IC can edit various permutations and combinations of duty cycles, and test the display process of the display panel respectively, and finally select one or more permutations with better adjustment effect on the flicker problem of the display panel for storage, and one or more duty cycle permutations can be selected for different display modes for storage for use by the display panel. In the embodiment of the present invention, from the perspective of adjusting the light-emitting duration, it is only necessary to edit and adjust the start signal through the driver IC, without changing the original structure of the pixel circuit and the display panel, which can effectively control the investment cost, and the debugging process is simpler and more flexible.

[0068] On the basis of the above-mentioned embodiments, optionally, the arrangement order of pulses with different duty cycles in the light-emitting control signal in each two adjacent display frames can be set to be different, so as to increase the chaos of the arrangement of the light-emitting control signal pulses, and further improve the probability of each brightness state matching a display frame that has an optimized adjustment effect on the brightness change trend.

[0069] On the basis of the above-mentioned embodiments, it can be optionally arranged that the duty cycle of each pulse of the light-emitting control signal in each display frame does not change monotonically, so that each display frame has the function of improving flicker in a wide brightness range, further improving the probability of each brightness matching a display frame that has an optimized adjustment effect on the brightness change trend, thereby ensuring the display effect. Moreover, such an arrangement makes it possible that the change trend of the light-emitting duration in each display frame is not simply increasing or decreasing, and the changes in the light-emitting duration and the brightness intensity are coordinated. In any display frame, under any brightness state, the light-emitting brightness can show a state of up and down jittering. Then, in each display frame, the length of the time period in which the light-emitting brightness rises or falls is less than the total duration of a display frame, compared to the following. Figure 3 and Figure 4 When the luminous brightness increases or decreases in a display frame, the duration of the rising and falling periods of the luminous brightness in each display frame can be made shorter and less noticeable to the human eye. Compared with the case where the luminous brightness changes monotonically, the up and down jittering of the luminous brightness may also have the effect of making the range of luminous brightness variation within a display frame smaller, thereby improving flicker and enhancing the user's visual experience.

[0070] On the basis of the above embodiments, optionally, based on power consumption considerations, the light emitting control signal may include 3-8 pulses in each display frame; for example, 3, 5 or 8 pulses. The duty ratios of the pulses of the light emitting control signal in a display frame may be partially or completely different. Preferably, in the same display frame, the duty ratios of the pulses in the light emitting control signal are different, so as to achieve more flexible and diverse arrangement control of the light emitting control signal pulses in each display frame.

[0071] On the basis of the above-mentioned embodiments, optionally, in at least two display frames, there are multiple implementations of different arrangement orders of pulses in the light emitting control signal, which are described below respectively.

[0072] In one implementation, optionally, in at least two display frames, the arrangement order of pulses in the light emitting control signal is different, including:

[0073] In multiple display frames, K types of light-emitting control signals are cyclically provided to the pixel circuit, wherein the duty cycles of at least two pulses in the same light-emitting control signal are different; the types and numbers of pulses in different types of light-emitting control signals are the same, but the arrangement order of the pulses is different; and K is greater than or equal to 2.

[0074] Combine the following Figure 5 This implementation method is described. Figure 5 is a waveform diagram of a light emitting control signal provided by an embodiment of the present invention. Figure 5 , taking K=3 as an example, illustratively, each light-emitting control signal includes three pulses, and the types of the three pulses are different (i.e., different duty cycles), the duty cycle of the first type of pulse is duty1, the duty cycle of the second type of pulse is duty2, and the duty cycle of the third type of pulse is duty3, duty1<duty2<duty3. The duty cycles of the pulses in the first type of light-emitting control signal Type1 are arranged as duty1→duty2→duty3, the duty cycles of the pulses in the second type of light-emitting control signal Type2 are arranged as duty2→duty3→duty1, and the duty cycles of the pulses in the third type of light-emitting control signal Type3 are arranged as duty3→duty1→duty2. Specifically, in the first display frame F1, the first light-emitting control signal Type1 may be provided to the pixel circuit, in the second display frame F2, the second light-emitting control signal Type2 may be provided to the pixel circuit, and in the third display frame F3, the third light-emitting control signal Type3 may be provided to the pixel circuit; the fourth display frame F4 is the same as the first display frame F1, and the first light-emitting control signal Type1 is provided to the pixel circuit. That is to say, in this embodiment, three display frames are used as a cycle, for example, display frames F1-F3 constitute the first cycle C1, and the above three light-emitting control signals are provided to each display frame cycle in the order in the above first cycle C1. Specifically, the first light-emitting control signal Type1 is provided to the 3i+1th display frame, the second light-emitting control signal Type2 is provided to the 3i+2th display frame, and the third light-emitting control signal Type3 is provided to the 3i+3th display frame, i≥0. Among them, the various light-emitting control signals in each display frame are continuous in time.

[0075] This embodiment cyclically provides K types of light-emitting control signals to the pixel circuit, so that the control logic of the pixel circuit driving process can be simple and easy to implement. In addition, in each type of light-emitting control signal, the pulse type and the number of each type of pulse are the same, so that the total light-emitting duration in each display frame is equal, and the brightness difference between different display frames caused by different light-emitting durations can be avoided.

[0076] The pulse composition mode of the above-mentioned light-emitting control signal and the value of K are not intended to limit the present invention. In other embodiments, optionally, the value of K can be determined according to the number of pulses of the light-emitting control signal in a display frame and the type of pulses of the light-emitting control signal. The pulse arrangement order in different types of light-emitting control signals can be different, and the specific arrangement order can be selected arbitrarily. Exemplarily, when a display frame includes n pulses of a light-emitting control signal, and the n pulses are of different types, there are at most n! types of arrangement of the pulses in a display frame, then the K value can be arbitrarily selected from 2-n!. When the n pulses include m types of pulses, m<n, and the arrangement of the pulses in a display frame is less than n! types, thereby limiting the upper limit of the value of K.

[0077] In order to verify the improvement effect of the method of providing K kinds of light control signals in a cycle on the flicker problem, the inventor built a test environment, adopted the JEITA standard, and used CA-VP410 to test the flicker data of the display module before and after the improvement when displaying at W127 grayscale. The test results can be found in Figure 6-Figure 9 .in, Figure 6-7 The test results before improvement are given when the pulse duty ratios of the light emitting control signals provided to each display subframe are the same using the prior art. Figure 8-9 The following table shows the test results of improving the system by providing multiple lighting control signals in a loop. Figure 6 The light-colored curve represents the luminous intensity, and the dark-colored curve represents the brightness. It can be seen that under high grayscale, the change trend of brightness is basically the same as Figure 3 Same as in , the brightness is gradually reduced in each display frame. Figure 7 , 15Hz and 30Hz are selected as the characteristic refresh frequencies. It can be seen that the flicker level is -39.8dB at 15Hz and -52.7dB at 30Hz. Figure 8 , the dark curve is also used to represent the brightness. It can be seen that under high grayscale, the change trend of brightness shows an up and down jitter state in each display frame. Fig. 9 , 15Hz and 30Hz are still selected as the characteristic refresh frequencies. It can be seen that the flicker level is -60.4dB at 15Hz and -55.5dB at 30Hz. Figure 6 and Figure 8 It can be seen that after adopting the method of this embodiment, the brightness jitter range in a display frame is reduced. Figure 7 and Fig. 9 It can be seen that after adopting the method of this embodiment, the flicker degree at each refresh frequency is reduced. The above test results show that the driving method provided by the embodiment of the present invention can effectively improve the flicker problem.

[0078] On the basis of the above-mentioned embodiments, optionally, the first display subframe in each display frame constitutes a refresh frame, and the other display subframes constitute a hold frame. In the refresh frame, data is written to the pixel circuit within the cut-off pulse of the light-emitting control signal; in the hold frame, data is no longer written to the pixel circuit. In practical applications, the light-emitting duration in the first display subframe can be determined according to the duty cycle of the first pulse in the display frame; further, the target light-emitting intensity of the light-emitting module can be determined according to the light-emitting duration in the first display subframe and the target brightness of the display frame, and the voltage value of the data voltage provided to the pixel circuit can be determined according to the target light-emitting intensity of the light-emitting module.

[0079] Exemplarily, the light control signal may include one pulse in a refresh frame and one pulse in a hold frame; in the same display frame, the duty cycle of the light control signal in the refresh frame is different from that in the hold frame.

[0080] Alternatively, the light control signal may include one pulse in the refresh frame and at least two pulses with different duty cycles in the hold frame. The duty cycles of the light control signal pulses in the refresh frame and the hold frame may be the same or different.

[0081] In another embodiment, the arrangement order of the pulses in the light control signal is different, including: the light control signal includes at least two pulses with different duty cycles, and the at least two pulses with different duty cycles are randomly arranged. That is, in each display frame, the duty cycles of multiple pulses of the light control signal can be randomly arranged. The waveform of the light control signal under this arrangement can be seen in Fig.10 For example, the types of pulses included in different display frames may be the same or different, for example, the first display frame F1, the second display frame F2 and the third display frame F3 each include three types of pulses, and the fourth display frame F4 includes two types of pulses. The pulse sequences of the light emitting control signals in adjacent display frames may be the same or different, for example, the sequences in the first display frame F1 and the second display frame F2 are different, and the sequences in the second display frame F2 and the third display frame F3 are the same.

[0082] When the pulses of the light-emitting control signal of each display sub-frame in each display frame are randomly arranged, the duty cycle of the light-emitting control signal in each refresh frame is different, so that the data voltage provided to the pixel circuit in each refresh frame needs to be adjusted according to two variables: the duty cycle of the light-emitting control signal and the target light-emitting intensity of the light-emitting module, and the control logic is relatively complicated.

[0083] In order to simplify the control logic, in different display frames, the duty cycle of the pulses of the light emitting control signal in each refresh frame can be set to be the same, and in the frame, the light emitting control signal EM includes at least two pulses with different duty cycles, and the at least two pulses with different duty cycles are randomly arranged. Fig.11 As shown, each refresh frame TA can be set to use the first type of pulse, that is, a pulse with a duty cycle of duty1; in each holding frame TI, various types of pulses can be set to be randomly arranged. This arrangement makes the light-emitting duration of the light-emitting module equal in each refresh frame TA, and the data voltage can be adjusted only according to the change of the target light-emitting intensity of the light-emitting module, which effectively simplifies the control logic. Exemplarily, in a display frame, the duty cycle of the pulse of the light-emitting control signal EM in the refresh frame TA can be the same as the duty cycle of any pulse of the light-emitting control signal EM in the holding frame TI, or it can be different from the duty cycle of all pulses of the light-emitting control signal EM in the holding frame TI. And, in the holding frame TI, the light-emitting control signal EM can include multiple pulses with the same duty cycle; or, in the holding frame TI, the duty cycles of all pulses of the light-emitting control signal EM can be different.

[0084] Based on the above embodiments, optionally, the total luminous duration in each display frame can be set to be equal, and based on this premise, the pulses of the luminous control signal in each display frame can be randomly arranged to reduce the brightness difference between the display frames caused by the different total luminous time.

[0085] Fig.12 is a flowchart of a driving method of a pixel circuit provided by an embodiment of the present invention. Fig.12 In another embodiment, optionally, the pulse arrangement sequence of the light emitting control signal can be determined according to the target brightness of each display frame. Specifically, the driving method includes:

[0086] S110 , obtaining a target brightness of each display frame in a display frame sequence.

[0087] Among them, each brightness corresponds to the optimal arrangement of different types of pulses of the light-emitting control signal, that is, a solution for reversely adjusting the light-emitting duration of each display subframe corresponding to the influence of the leakage of the driving transistor on the brightness.

[0088] S120 , determining an arrangement order of pulses in a light emitting control signal in each display frame based on a target brightness of each display frame.

[0089] Exemplarily, it can be set that when the target brightness is greater than the first brightness threshold (that is, when the target brightness is high brightness), the duty cycle of each pulse of the light control signal in the same display frame gradually decreases; and when the target brightness is less than the second brightness threshold (that is, when the target brightness is low brightness), the duty cycle of each pulse of the light control signal in the same display frame gradually increases. Wherein, the first brightness threshold is greater than or equal to the second brightness threshold.

[0090] S130, providing a light emitting control signal to the pixel circuit.

[0091] In this step, the light emitting control signal is provided to the pixel circuit according to the arrangement sequence of the pulses in the light emitting control signal in each display frame determined in S120.

[0092] This embodiment is configured such that the pulse sequence of the light emitting control signal that best matches each display frame can be selected based on the brightness of the display frame to drive the pixel circuit, thereby maximally improving the display flicker problem in the full brightness range.

[0093] An embodiment of the present invention further provides a display panel. Fig.13 is a schematic diagram of the structure of a display panel provided by an embodiment of the present invention. Fig.13 , exemplarily, the display panel 100 includes: a pixel circuit 10 and a light emitting control circuit 20; the pixel circuit 10 includes a light emitting module 12, and the pixel circuit 10 can be used as follows Figure 1 The light emitting control circuit 20 may adopt any shift register structure capable of realizing signal shift output, such as 10T3C or 13T3C in the prior art.

[0094] The output end of the light emitting control circuit 20 is connected to the light emitting control signal line 41, the pixel circuit 10 is connected to the light emitting control signal line 41, and the light emitting control circuit 20 is used to generate a light emitting control signal EM, and the light emitting control signal EM controls the light emitting duration of the light emitting module 12 in the pixel circuit 10 within a display frame. The light emitting control circuit 20 is used to output the light emitting control signal EM to the light emitting control signal line 41. In each display frame, the light emitting control signal EM includes at least two pulses with different duty cycles, and in at least two display frames, the arrangement order of the pulses in the light emitting control signal EM is different.

[0095] In the display panel provided by the embodiment of the present invention, the light-emitting control circuit 20 can transmit the light-emitting control signal EM to the pixel circuit 20 through the light-emitting control signal line 41. By controlling the light-emitting control signal EM to include at least two pulses with different duty cycles in each display frame, and changing the pulse sequence of the light-emitting control signal EM in different display frames, the pulse arrangement sequence of the light-emitting control signal EM in each display frame is randomly set, so that in different display frames, the change law of the light-emitting duration of each display subframe is different, so as to be compatible with high-brightness and low-brightness display applications, improve the probability of each brightness state matching the display frame with an optimized adjustment effect on the brightness change trend, maximize the improvement of the display flicker problem in the full brightness range, and help reduce the refresh frequency of the display panel 100, provide conditions for the continuous reduction of product power consumption, and enhance product competitiveness.

[0096] On the basis of the above embodiments, optionally, each level of light emitting control circuit 20 is cascade connected, such as Fig.13As shown, along the direction from top to bottom, the output end of the current-stage light-emitting control circuit 20 is electrically connected to the input end of the first-stage light-emitting control circuit 20.

[0097] Exemplarily, the display panel 100 further includes a driver IC 30 and a start signal line 42, and the driver IC 30 transmits a start signal to the input end of the first-stage light-emitting control circuit 20 through the start signal line 42; wherein the light-emitting control signals EM of each stage are step-by-step shift output signals of the start signal, and the driver IC 30 determines the order of each pulse in the subsequent light-emitting control signals EM of each stage by editing the order of each pulse in the start signal. Exemplarily, the display panel 100 further includes a plurality of data lines 43, and the driver IC 30 provides data voltages to the pixel circuit 10 through the data lines 43.

[0098] It should be noted that in each embodiment of the pixel circuit driving method, specific descriptions are given for different arrangements of the light emitting control signal EM pulses. These pulse arrangements of the light emitting control signal EM can all be considered as pulse arrangements of the start signal provided by the driver IC30, and repeated contents will not be repeated.

[0099] The embodiment of the present invention further provides a display device, including the display panel provided by any embodiment of the present invention, having corresponding beneficial effects. Exemplarily, the display device can be any product or component with display function, such as a mobile phone, a tablet computer, a television or a monitor.

[0100] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0101] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for driving a pixel circuit, characterized in that: include: Providing a light emitting control signal to the pixel circuit, wherein in each display frame, the light emitting control signal includes at least two pulses with different duty cycles; In at least two display frames, the arrangement order of the pulses in the light-emitting control signal is different. The pulse arrangement order of the light-emitting control signal in each display frame is set in a random order, so that in different display frames, the change pattern of the light-emitting duration of each display subframe is different, thereby improving the display flicker problem in the full brightness range.

2. The driving method of the pixel circuit according to claim 1, characterized in that: In at least two display frames, the pulses with different duty cycles in the light emitting control signal are arranged in different orders, including: In multiple display frames, multiple light-emitting control signals are cyclically provided to the pixel circuit, wherein the duty cycles of at least two pulses in the same light-emitting control signal are different; the types and numbers of pulses in different light-emitting control signals are the same, but the arrangement order of the pulses is different.

3. The driving method of the pixel circuit according to claim 1, characterized in that: The arrangement order of the pulses in the light-emitting control signal is different, including: the light-emitting control signal includes at least two pulses with different duty cycles, and the at least two pulses with different duty cycles are randomly arranged.

4. The driving method of the pixel circuit according to claim 1, characterized in that: One of the display frames includes a refresh frame and a hold frame; In the refresh frame, the light-emitting control signal includes one pulse, and in the hold frame, the light-emitting control signal includes at least two pulses with different duty cycles.

5. The driving method of the pixel circuit according to claim 4, characterized in that: In each refresh frame, the duty cycle of the pulses of the light emitting control signal is the same.

6. The driving method of the pixel circuit according to claim 1, characterized in that: One of the display frames includes a refresh frame and a hold frame; In the refresh frame, the light control signal includes one pulse, and in the hold frame, the light control signal includes one pulse; in the same display frame, the duty cycle of the light control signal in the refresh frame is different from that in the hold frame.

7. The driving method of the pixel circuit according to claim 1, characterized in that: Before providing the light emitting control signal to the pixel circuit, the method further includes: Obtaining the target brightness of each display frame in the display frame sequence; Based on the target brightness of each display frame, the arrangement order of the pulses in the light emitting control signal in each display frame is determined.

8. The driving method of the pixel circuit according to claim 7, characterized in that: When the target brightness is greater than the first brightness threshold, the duty cycle of each pulse of the light emitting control signal gradually decreases within the same display frame; When the target brightness is less than the second brightness threshold, the duty cycle of each pulse of the light emitting control signal gradually increases within the same display frame; The first brightness threshold is greater than or equal to the second brightness threshold.

9. The driving method of the pixel circuit according to claim 1, characterized in that: In each display frame, the light-emitting control signal includes 3-8 pulses.

10. The driving method of the pixel circuit according to claim 1, characterized in that: In the same display frame, the duty cycle of each pulse in the light emitting control signal is different.

11. A display panel, characterized in that: include: Pixel circuit and light emitting control circuit; The pixel circuit includes a light emitting module; The output end of the light-emitting control circuit is connected to the light-emitting control signal line, and the pixel circuit is connected to the light-emitting control signal line. The light-emitting control circuit is used to generate a light-emitting control signal, and the light-emitting control signal controls the light-emitting duration of the light-emitting module in the pixel circuit within a display frame; The light-emitting control circuit is used to output a light-emitting control signal to the light-emitting control signal line. In each display frame, the light-emitting control signal includes at least two pulses with different duty cycles. In at least two display frames, the arrangement order of the pulses in the light-emitting control signal is different. The pulse arrangement order of the light-emitting control signal in each display frame is set in a random order, so that in different display frames, the light-emitting duration of each display subframe has a different change pattern, thereby improving the display flicker problem within the full brightness range.

12. A display device, characterized in that: include: The display panel as claimed in claim 11.

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