Driving circuit, driving method of display panel and display device thereof

Abstract

The present application provides a driving circuit, a driving method for a display panel and a display device thereof. The driving circuit is used to drive the display panel, and includes a timing control circuit, a gamma voltage generating module and a voltage adjustment module; the voltage modulation module includes a charge pump circuit, and the input end and the output end of the charge pump circuit are electrically connected to the timing control module and the gamma voltage generating module respectively, so as to provide a gamma reference voltage to the gamma voltage generating module. After the display panel is switched to a variable refresh rate mode, the timing control module is used to detect the duration of the field blanking period in the current frame cycle in real time, and output a pulse control signal corresponding to the duty cycle according to the duration, so as to control the gamma reference voltage generated by the charge pump circuit to change accordingly with the change of the duty cycle of the pulse control signal, thereby causing the gamma voltage generated by the gamma voltage generating module to change accordingly. The gamma voltage output by the driving circuit has good real-time performance, and can reduce the brightness difference between the front and rear frames and the screen flicker.

Description

Technical Field

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

[0002] In recent years, with the breakthroughs in dynamic image production technology in fields such as e-sports and animation, in order to synchronize with the frame rate of dynamic images and reduce screen tearing, display devices with variable refresh rate (VRR) function have gradually become one of the mainstream products.

[0003] In the prior art, after the display panel switches to the VRR mode, due to the change in refresh rate, the duration of the field blanking period (Vblank) in the frame cycle will also change, which will cause different pixel leakage rates, and thus cause the display panel to have a large brightness difference or flicker when the refresh rate is changed; to solve this problem, a software VGC method is usually adopted. When the timing controller (TCON) detects Vblank, N groups of I2C instructions are added according to the duration of Vblank, and the address of the PMIC gamma voltage register that can be identified is added to the corresponding I2C instruction. After the VGC function is turned on, the gamma voltage compensation of the frequency is called at different frequencies in the VRR mode.

[0004] However, the software program calling method not only has the problem of response delay, but also causes the gamma voltage to change in steps, which makes it very easy for the end time of the field blanking period to be between the two sets of gamma voltages, resulting in a difference between the written gamma voltage and the gamma voltage required for the actual Vblank duration, affecting the display effect. Summary of the invention

[0005] The present application provides a driving circuit, a driving method for a display panel, and a display device thereof, aiming to solve the problems in the prior art of response delay caused by changing the gamma voltage by a software program call due to a change in refresh rate, and the difference between the gamma voltage written at the end of the field blanking period and the actually required gamma voltage, which affects the display effect.

[0006] In order to solve the above technical problems, the first technical solution provided by the present application is to provide a driving circuit. The driving circuit is used to drive a display panel, and the driving circuit includes:

[0007] A timing control module, used for providing a driving signal to the driving display panel;

[0008] A gamma voltage generating module, used for generating a gamma voltage to drive the display panel;

[0009] a voltage adjustment module, comprising a control input terminal and a signal output terminal, wherein the control input terminal is electrically connected to the timing control module, and the signal output terminal is electrically connected to the gamma voltage generation module to provide a gamma reference voltage to the gamma voltage generation module;

[0010] Wherein, the voltage adjustment module comprises a charge pump circuit, and the input end of the charge pump circuit is electrically connected to the timing control module through the control input end;

[0011] Among them, after the display panel switches to the variable refresh rate mode, the timing control module is also used to detect the duration of the field blanking period in the current frame cycle in real time, and output a pulse control signal with a corresponding duty cycle according to the duration of the field blanking period, so as to control the gamma reference voltage generated by the charge pump circuit to change accordingly with the change of the duty cycle of the pulse control signal, thereby making the gamma voltage generated by the gamma voltage generating module change with the duration of the field blanking period.

[0012] Among them, the timing control module includes a monitoring unit and a pulse width modulation unit, the monitoring unit is electrically connected to the pulse width modulation unit, and the monitoring unit is configured to detect the duration of the field blanking period in the current frame cycle in real time at a preset frequency, so as to control the pulse width modulation unit to generate the pulse control signal with the corresponding duty cycle, so that the duty cycle of the pulse control signal changes accordingly with the change of the duration of the field blanking period, thereby controlling the gamma reference voltage generated by the voltage adjustment module to change with the duration of the field blanking period.

[0013] Wherein, the voltage adjustment module further includes a voltage follower, and the output end of the charge pump circuit is electrically connected to the signal output end through the voltage follower to provide the gamma reference voltage to the gamma voltage generation module, so that the gamma voltage generation module divides the gamma reference voltage to generate the gamma voltages of each order;

[0014] The charge pump circuit is electrically connected to the voltage follower to form a reference voltage generating unit; the voltage adjustment module has a first reference voltage generating unit and a second reference voltage generating unit, which are respectively used to generate a first gamma reference voltage and a second gamma reference voltage, so that the gamma voltage generating module generates the corresponding gamma voltages of each order after voltage division according to the first gamma reference voltage and the second gamma reference voltage.

[0015] Wherein, the charge pump circuit includes a first capacitor, a second capacitor, a first diode and a second diode, the first electrode of the first capacitor is electrically connected to the control input terminal, the second electrode of the first capacitor is electrically connected to the third electrode of the second capacitor through the first diode, and the fourth electrode of the second capacitor is grounded; the charge pump circuit also has a reference signal terminal, the reference signal terminal is electrically connected to the node between the second electrode and the first diode through the second diode, and the node between the first diode and the third electrode is electrically connected to the output terminal of the charge pump circuit; wherein the reference signal terminal is connected to an internal reference voltage so that the charge pump circuit generates the gamma reference voltage according to the internal reference voltage and the pulse control signal of the corresponding duty cycle.

[0016] In order to solve the above technical problems, the second technical solution provided by the present application is: to provide a method for driving a display panel. The driving method is based on a driving circuit, and the driving circuit is the driving circuit involved in the above technical solution, wherein the timing control module and the gamma voltage generation module are respectively electrically connected to the display panel; the driving method includes:

[0017] In response to the display panel switching to the variable refresh rate mode, the timing control module detects the duration of the field blanking period in the current frame cycle in real time, and outputs a pulse control signal corresponding to the duty cycle according to the duration;

[0018] The voltage adjustment module receives the pulse control signal and generates a corresponding gamma reference voltage according to the duty cycle of the pulse control signal;

[0019] The gamma voltage generating module receives the gamma reference voltage, divides the gamma reference voltage and generates gamma voltages of various levels corresponding to the duration of the field blanking period;

[0020] The display panel receives the gamma voltages of each order and displays the current frame image.

[0021] The timing control module includes a monitoring unit and a pulse width modulation unit; in response to the display panel switching to a variable refresh rate mode, the timing control module detects the duration of the field blanking period in the current frame cycle in real time, and outputs a pulse control signal corresponding to the duty cycle according to the duration, including the following steps:

[0022] Determine whether the field blanking period in the current frame cycle has started;

[0023] In response to the start of the field blanking period in the current frame cycle, the monitoring unit detects the duration of the field blanking period in the current frame cycle in real time at a preset frequency;

[0024] Determine whether the duration reaches a preset time node;

[0025] In response to the duration reaching a preset time node, the pulse width modulation unit generates the pulse control signal corresponding to the duty cycle.

[0026] Wherein, in response to the display panel switching to the variable refresh rate mode, the timing control module detects the duration of the field blanking period in the current frame cycle in real time, and outputs the pulse control signal corresponding to the duty cycle according to the duration, and the step further includes:

[0027] In response to the field blanking period in the current frame cycle not ending, the monitoring unit detects the duration of the field blanking period in the current frame cycle in real time at a preset frequency;

[0028] In response to the end of the field blanking period in the current frame cycle, a step of determining whether the field blanking period in the current frame cycle has started is entered, and the pulse width modulation unit keeps the duty cycle of the pulse control signal unchanged.

[0029] The preset time node includes a plurality of preset time nodes arranged in chronological order.

[0030] Wherein, the voltage adjustment module has a first reference voltage generating unit and a second reference voltage generating unit;

[0031] The step of the voltage adjustment module receiving the pulse control signal and generating a corresponding gamma reference voltage according to the duty cycle of the pulse control signal specifically includes:

[0032] The first reference voltage generating unit receives the pulse control signal corresponding to the duty cycle, and generates a corresponding first gamma reference voltage according to the pulse control signal;

[0033] The second reference voltage generating unit receives the pulse control signal corresponding to the duty cycle, and generates a corresponding second gamma reference voltage according to the pulse control signal.

[0034] The steps of the gamma voltage generating module receiving the gamma reference voltage and dividing the gamma reference voltage to generate gamma voltages of various levels corresponding to the duration of the field blanking period include:

[0035] The gamma voltage generating module divides the first gamma reference voltage and the second gamma reference voltage and then outputs the corresponding gamma voltages of each level.

[0036] In order to solve the above technical problems, the third technical solution provided by the present application is to provide a display device. The display device includes:

[0037] A display panel, used for displaying frame images;

[0038] A driving circuit is electrically connected to the display panel and is used to drive the display panel; wherein the driving circuit is the driving circuit involved in the above technical solution, and a driving method for the driving circuit to drive the display panel is the driving method involved in the above technical solution.

[0039] Beneficial effects of the present application: Different from the prior art, the present application provides a driving circuit, a driving method for a display panel and a display device thereof, wherein the driving circuit is used to drive the display panel, and comprises a timing control module, a gamma voltage generating module and a voltage adjusting module; the present application enables the voltage adjusting module to include a charge pump circuit, and enables the input end of the charge pump circuit to be electrically connected to the timing control module through the control input end of the voltage adjusting module, and after the display panel is switched to a variable refresh rate (VRR) mode, enables the timing control module to detect in real time the duration of a field blanking period (Vblank) in a current frame cycle, and outputs a pulse control signal of a corresponding duty cycle according to the detected duration of the field blanking period, so as to control the gamma reference voltage generated by the charge pump circuit to change accordingly with the change of the duty cycle of the pulse control signal, thereby making the gamma reference voltage The gamma voltage generated by the voltage generating module changes with the duration of Vblank to output a gamma voltage corresponding to the duration of Vblank in the current frame period, thereby driving the display panel to display the current frame image; that is, by controlling the amplitude of the gamma reference voltage generated by the charge pump circuit in a pulse width modulation manner to provide the corresponding reference voltage to the gamma voltage generating module, the gamma voltage generating module generates a gamma voltage corresponding to the duration of Vblank in the current frame period according to the reference voltage, which not only effectively improves the matching degree of the current gamma voltage with the current refresh rate and frame rate, but also controls the gamma voltage in a pulse width modulation manner, which can effectively reduce the response delay and has better real-time performance, making the gamma voltage change process smoother, which can effectively improve the display quality and avoid the problem of brightness difference between the front and back frames and screen flickering on the display panel. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0041] Figure 1 is a schematic diagram of the structure of a driving circuit provided by an embodiment of the present application;

[0042] Figure 2is a timing diagram of a frame period and a gamma voltage after a display panel is switched to a VRR mode provided by an embodiment of the present application;

[0043] Figure 3 is a schematic structural diagram of a driving circuit provided by another embodiment of the present application;

[0044] Figure 4 is an equivalent circuit diagram of a gamma reference voltage generating unit provided in an embodiment of the present application;

[0045] Figure 5 is a schematic structural diagram of a display device provided by an embodiment of the present application;

[0046] Figure 6 is a schematic flow chart of a method for driving a display panel provided in one embodiment of the present application;

[0047] Figure 7 yes Figure 6 A schematic flow chart of a method for adjusting a gamma voltage provided in an embodiment.

[0048] Reference numerals:

[0049] 100-driving circuit; 10-timing control module; 11-monitoring unit; 12-pulse width modulation unit; 20-voltage adjustment module; 21-gamma reference voltage generating unit / first reference voltage generating unit; 211-charge pump circuit; 212-voltage follower; 22-second reference voltage generating unit; 23-control input terminal; 24-signal output terminal; 30-gamma voltage generating module; 200-display panel. DETAILED DESCRIPTION

[0050] The scheme of the embodiment of the present application is described in detail below in conjunction with the drawings of the specification.

[0051] In the following description, for the purpose of explanation rather than limitation, specific details such as specific system structures, interfaces, and technologies are provided to facilitate a thorough understanding of the present application.

[0052] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0053] The terms "first", "second", "third" in this application are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Thus, the features defined as "first", "second", "third" can expressly or implicitly include at least one of the features. In the description of this application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. In the embodiments of this application, all directional indications (such as up, down, left, right, front, back...) are only used to explain the relative position relationship, movement, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication also changes accordingly. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the steps or units listed, but optionally also includes steps or units that are not listed, or optionally also includes other steps or units inherent to these processes, methods, products or devices.

[0054] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0055] The present application is described in detail below with reference to the accompanying drawings and embodiments.

[0056] See also Figure 1 , Figure 1 1 is a schematic diagram of a driving circuit according to an embodiment of the present invention. In this embodiment, a driving circuit 100 is provided, which is used to drive a display panel 200 (see Figure 5 ) provides gamma voltages γ of various orders required for displaying frame images, so as to drive the display panel 200 to display frame images. Specifically, the driving circuit 100 includes a timing control module 10, a gamma voltage generating module 30 and a voltage adjusting module 20. Among them, the timing control module 10 is used to provide a driving signal to the display panel 200 to drive the row driving module and the column driving module of the display panel 200; the gamma voltage generating module 30 is used to generate gamma voltages γ of various orders, so as to drive the display panel 200 to display frame images; the voltage adjusting module 20 has a control input terminal 23 and a signal output terminal 24, the control input terminal 23 is electrically connected to the timing control module 10, and the signal output terminal 24 is electrically connected to the gamma voltage generating module 30, so as to provide the gamma reference voltage Vgar to the gamma voltage generating module 30.

[0057] In the present embodiment, after the display panel 200 switches to the VRR mode, the timing control module 10 is further used to detect in real time the duration of the field blanking period of the current frame period FT, and output a pulse control signal PWM corresponding to the duty cycle according to the duration, so as to control the amplitude of the gamma reference voltage Vgar generated by the voltage adjustment module 20, so that the gamma voltage generation module 30 changes the magnitude of the gamma voltage γ after receiving the gamma reference voltage Vgar to correspond to the duration of the field blanking period of the current frame period FT, so as to provide the display panel 200 with the gamma voltage γ required for the current frame image, thereby avoiding the display panel 200 having a large brightness difference between the previous and next frames or flickering due to a change in the refresh rate.

[0058] Specifically, the timing control module 10 includes a monitoring unit 11 and a pulse width modulation unit 12. The monitoring unit 11 is electrically connected to the pulse width modulation unit 12. The monitoring unit 11 is configured to detect the duration of the field blanking period in the current frame period FT in real time at a preset frequency to control the pulse width modulation unit 12 to generate a pulse control signal PWM with a corresponding duty cycle, so that the duty cycle of the pulse control signal PWM changes accordingly with the change of the duration of the field blanking period, thereby controlling the gamma reference voltage Vgar generated by the voltage adjustment module 20 to change with the duration of the field blanking period.

[0059] See also Figure 2 , Figure 2It is a timing diagram of the frame period FT and the gamma voltage after the display panel is switched to the VRR mode provided by an embodiment of the present application. In a specific embodiment, after the display panel 200 is switched to the VRR mode, each frame period FT may include an effective period with a constant length and a field blanking period with a variable length. When the length of the field blanking period changes, the frame period FT changes accordingly, and the refresh rate of the display panel 200 also changes accordingly to match the frame rate. In this embodiment, the change in the length of the field blanking period and the change in the gamma voltage γ when the refresh rate changes from f1 to f2 after the display panel 200 is switched to the VRR mode are exemplarily shown. Specifically, when the refresh rate is f1, the frame period FT is FT1, and FT1 and f1 are reciprocal to each other; at the refresh rate f1, the frame period FT1 includes an effective period AP1 and a field blanking period BP1, and the sum of the length of the effective period AP1 and the length of the field blanking period BP1 is equal to the length of the frame period FT1, and the gamma voltage γ corresponding to the refresh rate f1 is V1. When the refresh rate changes from f1 to f2, the frame period FT becomes FT2, and FT2 and f2 are reciprocals of each other; at the refresh rate f2, the frame period FT2 includes an effective period AP2 and a field blanking period BP2, the length of the effective period AP2 is equal to the length of the effective period AP1, and the field blanking period BP2 changes with the change of the refresh rate f, so the length of the field blanking period BP2 is different from the field blanking period BP1. In this embodiment, the refresh rate f2 is less than the refresh rate f1, and the length of the field blanking period BP2 is greater than the length of the field blanking period BP1.

[0060] Specifically, in this embodiment, after the display panel 200 switches to the VRR mode, the monitoring unit 11 in the timing control module 10 is configured to detect the duration of the field blanking period in the current frame period FT in real time at a preset frequency; for example, when the current frame period FT is FT1, the monitoring unit 11 detects the duration of the field blanking period AP1 in the current frame period FT1 in real time at a preset frequency, and when the duration of the field blanking period AP1 reaches the first preset time node t1, the field blanking period AP1 ends, and the refresh rate f1 corresponding to the current frame is equal to the rated refresh rate of the display panel 200, and the monitoring unit 11 controls the duty cycle of the pulse control signal PWM1 generated by the pulse width modulation unit 12 to remain unchanged, thereby controlling the gamma reference voltage Vgar generated by the voltage adjustment module 20 to remain unchanged, so that the gamma voltage γ generated by the gamma voltage γ generating unit remains unchanged, so as to be consistent with the gamma voltage γ required by the display panel 200. It should be noted that the time length from the field blanking period AP1 to the first preset time node t1 is usually set to the same as the time length of the field blanking period AP0 in the constant refresh rate mode.

[0061] The frame period FT1 ends and enters the next frame period FT2, that is, the current frame period FT is FT2, and the monitoring unit 11 continues to detect the duration of the field blanking period BP2 in the current frame period FT2 in real time at a preset frequency. When the duration of the field blanking period BP2 reaches the first preset time node t1 and the field blanking period BP2 has not ended, the monitoring unit 11 controls the pulse width modulation unit 12 to generate a pulse signal PWM2 corresponding to the duty cycle, and then controls the amplitude change of the gamma reference voltage Vgar generated by the voltage adjustment module 20, so that the gamma voltage γ generated by the gamma voltage generation module 30 can match the gamma voltage γ required by the display panel 200 at the current time node. As the duration of the field blanking period BP2 increases, when the second preset time node t2 is reached and the field blanking period BP2 has not ended, the pulse width modulation unit 12 is controlled to generate a pulse signal PWM3 corresponding to the duty cycle of the second preset time node t2, thereby controlling the amplitude of the gamma reference voltage Vgar generated by the voltage adjustment module 20 to change, so that the gamma voltage γ generated by the gamma voltage generation module 30 can match the gamma voltage γ required by the display panel 200 at the current time node. Similarly, every time the duration of the field blanking period AP2 in the current frame period FT2 reaches a preset time node tk (k=1,2,3,…,n, where n is a positive integer), the monitoring unit 11 controls the pulse width modulation unit 12 to generate a pulse signal PWM(k+1) (k=1,2,3,…,n, where n is a positive integer) of a duty cycle corresponding to the preset time node tk, and then controls the amplitude of the gamma reference voltage Vgar generated by the voltage adjustment module 20 to change with the change of the duty cycle until the field blanking period BP2 in the current frame period FT2 ends. During the field blanking period BP2, the timing control module 1 0 detects the duration of the field blanking period AP2 in real time and outputs a pulse control signal PWM(k+1) corresponding to the duty cycle to control the amplitude of the gamma reference voltage Vgar generated by the voltage adjustment module 20, thereby changing the magnitude of the gamma voltage γ generated by the gamma voltage generation module 30, that is, the gamma voltage γ is adjusted in real time by pulse width modulation in the field blanking period BP2, so that the gamma voltage γ generated by the gamma voltage γ generation unit can always be the same or substantially the same as the gamma voltage γ required by the display panel 200, effectively improving the matching degree between the gamma voltage γ generated by the driving circuit 100 and the gamma voltage γ actually required by the display panel 200. At the same time, in this embodiment, the change process of the gamma voltage γ can be made smoother by optimizing the preset frequency of the monitoring unit 11 and optimizing the time between adjacent preset time nodes tk and t(k+1) in the field blanking period, which can further improve the real-time performance of the driving circuit 100, reduce the response delay, and thus effectively improve the display quality, avoiding the problem of brightness difference between the front and back frames and screen flickering on the display panel 200.

[0062] In this embodiment, the voltage adjustment module 20 includes a charge pump circuit, and the input end of the charge pump circuit is electrically connected to the timing control module 10 through the control input end 23. Specifically, the voltage adjustment module 20 has a reference voltage generation unit, and the reference voltage generation unit is formed by electrically connecting the charge pump circuit and the voltage follower. The output end of the charge pump circuit is electrically connected to the signal output end 24 of the timing control module 10 through the voltage follower to provide the above-mentioned gamma reference voltage Vgar to the gamma voltage generation module 30, so that the gamma voltage generation module 30 of the monitoring unit 11 divides the gamma reference voltage Vgar of the monitoring unit 11 to generate the gamma voltage γ of each level of the monitoring unit 11. Among them, the charge pump circuit is used to generate the gamma reference voltage Vgar, and the voltage follower is used to provide the load capacity of the circuit and improve the driving capability. In this embodiment, the voltage adjustment module 20 may have a reference voltage generating unit for providing a high-voltage reference voltage of the gamma reference voltage Vgar to the gamma voltage generating module 30. The gamma voltage generating module 30 divides the voltage according to its own low-voltage reference voltage and the high-voltage reference voltage provided by the voltage adjustment module 20, thereby generating a gamma voltage γ corresponding to each grayscale value to drive the display panel 200, that is, each gamma voltage γ1-γn generated by the gamma voltage generating module 30 is obtained by dividing the low-voltage reference voltage and the high-voltage reference voltage. It is easy to understand that in this embodiment, the magnitude of the high-voltage reference voltage required by the gamma voltage generating module 30 is controlled by pulse width modulation, thereby controlling the magnitude of the gamma voltage γ, so that the magnitude of the gamma voltage γ output by the driving circuit 100 is always the same or substantially the same as the gamma voltage γ actually required by the display panel 200, effectively improving the matching degree between the gamma voltage γ generated by the driving circuit 100 and the gamma voltage γ actually required by the display panel 200.

[0063] See also Figure 3 , Figure 3 is a schematic diagram of the structure of a driving circuit provided by another embodiment of the present application. Figure 1Different from the embodiment, in this embodiment, the voltage adjustment module 20 has two gamma reference voltage generating units 21, namely the first gamma reference voltage generating unit 21 and the second gamma reference voltage generating unit 21, which are respectively used to generate the first gamma reference voltage Vgar1 and the second gamma reference voltage Vgar2, so that the gamma voltage generating module 30 generates the corresponding gamma voltages γ of each order after voltage division according to the first gamma reference voltage Vgar1 and the second gamma reference voltage Vgar2. Among them, the first gamma reference voltage Vgar1 is the low voltage reference voltage required by the gamma voltage generating module 30, and the second gamma reference voltage Vgar2 is the high voltage reference voltage required by the gamma voltage generating module 30. The gamma voltage generating module 30 divides the first gamma reference voltage Vgar1 and the second gamma reference voltage Vgar2 to generate gamma voltages γ1~γn corresponding to each order of grayscale values ​​to drive the display panel 200. Figure 1 Compared with the embodiment, in this embodiment, the high-voltage reference voltage and the low-voltage reference voltage required by the gamma voltage generating module 30 can be changed at the same time to change the size of each order of gamma voltage γ1~γn, so that the adjustable range of the gamma voltage γ can be larger, and the gamma voltage γ output by the driving circuit 100 can be more accurate, thereby further improving the matching degree between the gamma voltage γ output by the driving circuit 100 and the voltage actually required by the display panel 200.

[0064] See also Figure 4 , Figure 4 : is an equivalent circuit diagram of a gamma reference voltage generating unit provided by an embodiment of the present application. Specifically, the charge pump circuit includes a first capacitor C1, a second capacitor C2, a first diode D1 and a second diode D2, the first electrode C11 of the first capacitor C1 is electrically connected to the control input terminal 23, the second electrode C12 of the first capacitor C1 is electrically connected to the third electrode C21 of the second capacitor C2 through the first diode D1, and the fourth electrode C22 of the second capacitor C2 is grounded GND; the charge pump circuit also has a reference signal terminal, the reference signal terminal is electrically connected to the node between the second electrode C12 and the first diode D1 through the second diode D2, and the node between the first diode D1 and the third electrode C21 is electrically connected to the output terminal of the charge pump circuit; wherein the reference signal terminal is connected to the internal reference voltage Vref, so that the charge pump circuit generates the gamma reference voltage Vgar according to the internal reference voltage Vref and the pulse control signal PWM corresponding to the duty cycle; the output terminal of the charge pump circuit is electrically connected to the positive input terminal of the voltage follower, so as to provide the gamma reference voltage Vgar to the gamma voltage generating module 30 through the voltage follower. Furthermore, the output terminal of the voltage follower is electrically connected to the signal output terminal 24 via a third diode D3, and the third diode D3 is used to slightly reduce the voltage to output the gamma reference voltage Vgar.

[0065] Specifically, the pulse control signal PWM corresponding to the duty cycle generated by the timing control module 10 is connected to the input end of the charge pump circuit by the control input end 23 of the voltage adjustment module 20, and the low level of the pulse control signal PWM is Vl, and the high level is Vh. At the low level of the pulse control signal PWM, the first capacitor C1 is in a charging state, the voltage at the first electrode C11 is Vl, and the voltage at the second electrode C12 is increased to Vref; the second capacitor C2 is in a charging state, the voltage at the third electrode C21 is increased to Vref, the voltage at the fourth electrode C22 is 0, the voltage difference at both ends of the second capacitor C2 is Vref, and the voltage at the output end of the charge pump circuit is Vref. In the high level phase of the pulse control signal PWM, the first capacitor C1 is reversely charged, the voltage at the first electrode C11 is increased to Vh, due to the coupling effect of the capacitor, the voltage at the second electrode C12 becomes Vref+(Vh-Vl), the second capacitor C2 is in a discharge state, the voltage at the third electrode C21 becomes Vref+(Vh-Vl), and the voltage at the fourth electrode C22 is 0. It can be seen that the voltage range of the output end of the charge pump circuit is Vref~(Vref+Vh-Vl), that is, the range of the gamma reference voltage Vgar provided by the gamma reference voltage Vgar generation unit 21 to the gamma voltage generation module 30 is Vref~(Vref+Vh-Vl), and the gamma reference voltage Vgar can be specifically controlled by adjusting the duty cycle of the pulse control signal PWM.

[0066] Specifically, in Figure 1 In an embodiment, the minimum and maximum values ​​of the gamma reference voltage Vgar can be further set by setting the values ​​of the low level Vl and the high level Vh of the pulse control signal PWM and the value of the internal reference voltage Vref, thereby satisfying the gamma voltages γ1 to γn of each order required by the display panel 200 at different refresh rates.

[0067] Similarly, in Figure 3 In the embodiment, the minimum value and the maximum value of the first gamma reference voltage Vgar1 and the minimum value and the maximum value of the second gamma reference voltage Vgar2 can be set respectively by setting the values ​​of the low level Vl and the high level Vh of the pulse control signal PWM, and the values ​​of the first internal reference voltage Vref1 of the first gamma reference voltage generating unit 21 and the second internal reference voltage Vref2 of the second gamma reference voltage generating unit 21, so as to meet the requirements of the gamma voltages γ1 to γn of each order of the display panel 200 at different refresh rates.

[0068] The driving circuit 100 provided in the above embodiment can not only solve the problem that the traditional display panel 200 changes the gamma voltage γ due to the response delay caused by the software program call method when changing the refresh rate, and the gamma voltage γ written at the end of the field blanking period is different from the actually required gamma voltage γ, which affects the display effect; moreover, the driving circuit 100 has a simple structure, is easy to implement and mass-produce, can effectively reduce the use of chips, and reduce production costs.

[0069] See also Figure 5 , Figure 5 1 is a schematic diagram of the structure of a display device provided in an embodiment of the present application. In this embodiment, a display device is provided, and the display device includes a display panel 200 and a drive circuit 100. The display panel 200 is used to display a frame image, and the display panel 200 can be a liquid crystal display panel 200, an LED display panel 200, an OLED display panel 200, or an electrophoretic display panel 200.

[0070] The driving circuit 100 is electrically connected to the display panel 200 to provide a driving signal to the display panel 200, thereby driving the display panel 200 to display a frame image. Specifically, the specific structure and function of the driving circuit 100 are the same or similar to the specific structure and function of the driving circuit 100 involved in the above embodiment, and can achieve the same technical effect. For details, please refer to the above introduction, which will not be repeated here.

[0071] The driving method of the display panel 200 driven by the driving circuit 100 will not be described in detail here. Please refer to the detailed description below for the driving method.

[0072] See also Figure 6 , Figure 6 1 is a flow chart of a method for driving a display panel provided in one embodiment of the present application. In this embodiment, a method for driving a display panel 200 is provided, and the method for driving a display panel 200 is based on the driving circuit 100 involved in the above embodiment. The timing control module 10 and the gamma voltage generating module 30 in the driving circuit 100 are respectively electrically connected to the display panel 200 to monitor the working mode, refresh rate and duration of the current corresponding field blanking period of the display panel 200, and provide the gamma voltage γ and various other driving signals to the display panel 200.

[0073] Specifically, the driving method of the display panel 200 includes the following steps:

[0074] S1: In response to the display panel 200 switching to the variable refresh rate mode, the timing control module 10 detects the duration of the field blanking period in the current frame period FT in real time, and outputs a pulse control signal PWM corresponding to the duty cycle according to the duration.

[0075] S2: The voltage adjustment module 20 receives the pulse control signal PWM, and generates a corresponding gamma reference voltage Vgar according to the duty cycle of the pulse control signal PWM.

[0076] S3: the gamma voltage generating module 30 receives the gamma reference voltage Vgar, divides the gamma reference voltage Vgar and generates gamma voltages γ of various levels corresponding to the duration of the field blanking period.

[0077] S4: the display panel 200 receives the gamma voltages γ of various levels and displays the current frame.

[0078] In this embodiment, when the display panel 200 is switched to the VRR mode, the timing control module 10 responds to the switching command. In each frame, the timing control module 10 detects the duration of the field blanking period in the current frame period FT in real time, and outputs a pulse control signal PWM corresponding to the duty cycle according to the detected duration. Then, the voltage adjustment module 20 generates a corresponding gamma reference voltage Vgar according to the duty cycle of the pulse control signal PWM. The gamma voltage generation module 30 receives the gamma reference voltage Vgar, and then divides the gamma reference voltage Vgar to generate gamma voltages γ of various levels corresponding to the duration of the field blanking period in the current frame period FT, and each gamma voltage γ corresponds to each grayscale value.

[0079] In this embodiment, the gamma voltage γ is adjusted in real time by pulse width modulation during the field blanking period, so that the gamma voltage γ generated by the gamma voltage γ generating unit can always be the same or substantially the same as the gamma voltage γ required by the display panel 200, effectively improving the matching degree between the gamma voltage γ generated by the driving method and the gamma voltage γ actually required by the display panel 200. At the same time, by controlling the gamma voltage γ by pulse width modulation, the response delay can be effectively reduced, and the real-time performance is good, so that the process of the gamma voltage γ change is smoother, which can effectively improve the display quality and avoid the problem of brightness difference between the front and back frames and screen flickering on the display panel 200.

[0080] See also Figure 7 , Figure 7 yes Figure 6 Schematic diagram of the gamma voltage adjustment method provided in the embodiment. In this embodiment, the timing control module 10 includes a monitoring unit 11 and a pulse width modulation unit 12, and the monitoring unit 11 is electrically connected to the pulse width modulation unit 12. Among them, step S1 may specifically include the following steps:

[0081] S11: Determine whether the field blanking period in the current frame period FT has started.

[0082] S12: In response to the start of the field blanking period in the current frame period FT, the monitoring unit 11 detects the duration of the field blanking period in the current frame period FT in real time at a preset frequency.

[0083] S13: Determine whether the duration reaches a preset time node.

[0084] S14: In response to the duration reaching a preset time node, the pulse width modulation unit 12 generates a pulse control signal PWM corresponding to the duty cycle.

[0085] In this embodiment, when the display panel 200 switches to the VRR mode, the timing control module 10 determines whether the field blanking period in the current frame period FT starts according to the duration of the current frame period FT monitored. Figure 2 When the monitored duration of the current frame period FT is less than the duration of the valid period in the frame period FT, the midfield blanking period of the current frame period FT has not yet started. The timing control module 10 continues to monitor the duration of the current frame period FT until the duration of the current frame period FT is equal to the length of the valid period in the frame period FT, then the midfield blanking period of the current frame period FT starts.

[0086] After the field blanking period in the current frame period FT begins, the monitoring unit 11 responds to the start of the field blanking period and then detects the duration of the field blanking period in the current frame period FT in real time at a preset frequency. The preset frequency can be optimized and set according to actual needs to improve the real-time performance of the driving method, and there is no specific limitation on this.

[0087] Specifically, a plurality of preset time nodes are set in a time sequence in the field blanking period in each frame period FT. The timing control module 10 determines whether the detected duration reaches the preset time node. If the preset time node is reached, in response to the duration reaching the preset time node, the monitoring unit 11 controls the pulse width modulation unit 12 to generate a pulse control signal PWM corresponding to the duty cycle; if the preset time node is not reached, the pulse width modulation unit 12 is controlled to keep the duty cycle of the output pulse control signal PWM unchanged, and continues to determine whether the current duration reaches the preset time node according to the duration of the field blanking period in the current frame period FT detected in real time by the monitoring unit 11. Among them, the plurality of preset time nodes are set in a time sequence in the field blanking period in each frame period FT, the shorter the duration between adjacent preset time nodes, the more the number of preset time nodes, the smoother the change of the gamma voltage γ with the increase of the duration of the field blanking period, the better the real-time performance, and the closer the gamma voltage γ finally outputted is to the gamma voltage γ required for the refresh rate corresponding to the display panel 200, the better the display effect of the display panel 200. Specifically, the duration between adjacent preset time nodes can be set according to actual needs and is not specifically limited.

[0088] In other embodiments, the field blanking period in each frame period FT may be divided into a plurality of preset time periods in chronological order, and the timing control module 10 outputs a pulse control signal PWM corresponding to the duty cycle by determining the preset time period in which the detected duration is located. The duration of each preset time period may be set according to actual needs, and the duration of each preset time period may be the same or different, and there is no specific limitation on this.

[0089] Further, in a specific implementation, the voltage adjustment module 20 may include a first reference voltage generating unit 21 and a second reference voltage generating unit; step S2 may specifically include:

[0090] S21 : The first reference voltage generating unit 21 receives a pulse control signal PWM corresponding to a duty cycle, and generates a corresponding first gamma reference voltage Vgar1 according to the pulse control signal PWM.

[0091] S22: The second reference voltage generating unit 22 receives the pulse control signal PWM corresponding to the duty cycle, and generates a corresponding second gamma reference voltage Vgar2 according to the pulse control signal PWM.

[0092] Specifically, step S21 is executed synchronously with step S22. In step S21, the first reference voltage generating unit 21 generates a first gamma reference voltage Vgar1 corresponding to the duration of the current field blanking period according to the pulse control signal PWM, so as to provide the required low-voltage reference voltage to the gamma voltage generating module 30. In step S22, the second reference voltage generating unit 22 generates a second gamma reference voltage Vgar2 corresponding to the duration of the current field blanking period according to the pulse control signal PWM, so as to provide the required high-voltage reference voltage to the gamma voltage generating module 30.

[0093] Furthermore, step S3 specifically includes: the gamma voltage generating module 30 divides the first gamma reference voltage Vgar1 and the second gamma reference voltage Vgar2 and then outputs corresponding gamma voltages γ1 to γn of each order.

[0094] Specifically, the voltage adjustment unit simultaneously provides the low-voltage reference voltage and the high-voltage reference voltage required by the gamma voltage generating module 30. The gamma voltage generating module 30 can perform voltage division based on the low-voltage reference voltage and the high-voltage reference voltage to generate gamma voltages γ1~γn corresponding to each level of grayscale value. By adjusting the low-voltage reference voltage and the high-voltage reference voltage, the gamma voltages γ1~γn of each level can be changed accordingly to correspond to the refresh rate of the current display panel 200.

[0095] In this embodiment, by simultaneously changing the high voltage reference voltage and the low voltage reference voltage required by the gamma voltage generating module 30 to change the size of each order of gamma voltage γ, the adjustable range of the gamma voltage γ can be made larger, so that the gamma voltage γ output by the driving circuit 100 is more accurate, thereby further improving the matching degree between the gamma voltage γ output by the driving circuit 100 and the voltage actually required by the display panel 200.

[0096] Furthermore, in this embodiment, step S1 further includes:

[0097] In response to the field blanking period in the current frame period FT not being ended, the monitoring unit 11 detects the duration of the field blanking period in the current frame period FT in real time at a preset frequency.

[0098] In response to the end of the field blanking period in the current frame period FT, the step of determining whether the field blanking period in the current frame period FT starts is entered, and the pulse width modulation unit 12 keeps the duty cycle of the pulse control signal PWM unchanged.

[0099] Specifically, Figure 7 As shown, in the process of detecting the duration of the midfield blanking period in the current frame period FT, the timing control unit also needs to continuously determine whether the field blanking period is ended; if the field blanking period is not ended, then enter step S12 and loop the following steps until the midfield blanking period in the current frame period FT is ended; if the field blanking period is ended, then enter step S11 and loop the following steps.

[0100] The driving method of the display panel 200 provided in the above embodiment, when the display panel 200 switches to the VRR mode, during the field blanking period, the driving method adjusts the gamma voltage γ in real time by means of pulse width modulation, so that the gamma voltage γ generated by the gamma voltage γ generating unit can always be the same or substantially the same as the gamma voltage γ required by the display panel 200, and effectively improves the matching degree between the gamma voltage γ generated by the driving method and the gamma voltage γ actually required by the display panel 200. At the same time, by controlling the gamma voltage γ by means of pulse width modulation, the response delay can be effectively reduced, and the real-time performance is good, so that the process of the gamma voltage γ change is smoother, which can effectively improve the display quality and avoid the problem of brightness difference between the front and back frames and screen flickering in the display panel 200.

[0101] The above are only implementation methods of the present application, and are not intended to limit the patent protection scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A driving circuit for driving a display panel, the driving circuit comprising: A timing control module, used for providing a driving signal to the driving display panel; The timing control module includes a monitoring unit and a pulse width modulation unit, and the monitoring unit is electrically connected to the pulse width modulation unit; A gamma voltage generating module, used for generating a gamma voltage to drive the display panel; a voltage adjustment module, comprising a control input terminal and a signal output terminal, wherein the control input terminal is electrically connected to the timing control module, and the signal output terminal is electrically connected to the gamma voltage generation module to provide a gamma reference voltage to the gamma voltage generation module; The voltage adjustment module comprises a charge pump circuit and a voltage follower, the input end of the charge pump circuit is electrically connected to the timing control module through the control input end, and the output end of the charge pump circuit is electrically connected to the signal output end through the voltage follower to provide the gamma reference voltage to the gamma voltage generation module; wherein the charge pump circuit and the voltage follower are electrically connected to form a reference voltage generation unit; Wherein, after the display panel switches to the variable refresh rate mode, the timing control module is further used to detect the duration of the field blanking period in the current frame cycle in real time. Every time the duration of the field blanking period reaches a preset time node, the monitoring unit controls the pulse width modulation unit to generate a pulse control signal corresponding to the duty cycle of the time node, so as to control the amplitude of the gamma reference voltage generated by the charge pump circuit to change accordingly with the change of the duty cycle of the pulse control signal, thereby making the gamma voltage generated by the gamma voltage generation module change with the duration of the field blanking period until the field blanking period in the current frame cycle ends; by controlling the duration between adjacent preset time nodes in the field blanking period, the smoothness of the change of the gamma voltage is controlled; Wherein, the voltage adjustment module has a reference voltage generating unit for providing a high-voltage reference voltage of a gamma reference voltage to the gamma voltage generating module, and the gamma voltage generating module divides the high-voltage reference voltage according to its own low-voltage reference voltage to generate the gamma voltage corresponding to each grayscale value; or, The voltage adjustment module has a first reference voltage generating unit and a second reference voltage generating unit, which are respectively used to generate a first gamma reference voltage and a second gamma reference voltage, wherein the first gamma reference voltage is a low-voltage reference voltage required by the gamma voltage generating module, and the second gamma reference voltage is a high-voltage reference voltage required by the gamma voltage generating module, and the gamma voltage generating module performs voltage division according to the first gamma reference voltage and the second gamma reference voltage to generate the gamma voltage corresponding to each grayscale value.

2. The driving circuit according to claim 1, characterized in that: The monitoring unit is configured to detect the duration of the field blanking period in the current frame cycle in real time at a preset frequency, so as to control the pulse width modulation unit to generate the pulse control signal with the corresponding duty cycle, so that the duty cycle of the pulse control signal changes accordingly with the change of the duration of the field blanking period, thereby controlling the gamma reference voltage generated by the voltage adjustment module to change with the duration of the field blanking period.

3. The driving circuit according to claim 1, characterized in that: The charge pump circuit includes a first capacitor, a second capacitor, a first diode and a second diode, wherein the first electrode of the first capacitor is electrically connected to the control input terminal, the second electrode of the first capacitor is electrically connected to the third electrode of the second capacitor through the first diode, and the fourth electrode of the second capacitor is grounded; the charge pump circuit also has a reference signal terminal, wherein the reference signal terminal is electrically connected to a node between the second electrode and the first diode through the second diode, and the node between the first diode and the third electrode is electrically connected to an output terminal of the charge pump circuit; wherein the reference signal terminal is connected to an internal reference voltage so that the charge pump circuit generates the gamma reference voltage according to the internal reference voltage and the pulse control signal of the corresponding duty cycle.

4. A method for driving a display panel, based on a driving circuit, wherein the driving circuit is the driving circuit according to any one of claims 1 to 3, wherein: The timing control module and the gamma voltage generation module are electrically connected to the display panel respectively; characterized in that the driving method includes: In response to the display panel switching to the variable refresh rate mode, the timing control module detects the duration of the field blanking period in the current frame cycle in real time, and outputs a pulse control signal corresponding to the duty cycle according to the duration; The voltage adjustment module receives the pulse control signal and generates a corresponding gamma reference voltage according to the duty cycle of the pulse control signal; The gamma voltage generating module receives the gamma reference voltage, divides the gamma reference voltage and generates gamma voltages of various levels corresponding to the duration of the field blanking period; The display panel receives the gamma voltages of each order and displays the current frame image.

5. The driving method according to claim 4, characterized in that: The timing control module includes a monitoring unit and a pulse width modulation unit; in response to the display panel switching to a variable refresh rate mode, the timing control module detects the duration of the field blanking period in the current frame cycle in real time, and outputs a pulse control signal corresponding to the duty cycle according to the duration, including the following steps: Determine whether the field blanking period in the current frame cycle has started; In response to the start of the field blanking period in the current frame cycle, the monitoring unit detects the duration of the field blanking period in the current frame cycle in real time at a preset frequency; Determine whether the duration reaches a preset time node; In response to the duration reaching a preset time node, the pulse width modulation unit generates the pulse control signal corresponding to the duty cycle.

6. The driving method according to claim 5, characterized in that: In response to the display panel switching to the variable refresh rate mode, the timing control module detects the duration of the field blanking period in the current frame cycle in real time, and outputs the pulse control signal corresponding to the duty cycle according to the duration, which also includes: In response to the field blanking period in the current frame cycle not ending, the monitoring unit detects the duration of the field blanking period in the current frame cycle in real time at a preset frequency; In response to the end of the field blanking period in the current frame cycle, a step of determining whether the field blanking period in the current frame cycle has started is entered, and the pulse width modulation unit keeps the duty cycle of the pulse control signal unchanged.

7. The driving method according to claim 5, characterized in that: The preset time node includes a plurality of the preset time nodes arranged in chronological order.

8. The driving method according to claim 4, characterized in that: The voltage adjustment module has a first reference voltage generating unit and a second reference voltage generating unit; The step of the voltage adjustment module receiving the pulse control signal and generating a corresponding gamma reference voltage according to the duty cycle of the pulse control signal specifically includes: The first reference voltage generating unit receives the pulse control signal corresponding to the duty cycle, and generates a corresponding first gamma reference voltage according to the pulse control signal; The second reference voltage generating unit receives the pulse control signal corresponding to the duty cycle, and generates a corresponding second gamma reference voltage according to the pulse control signal; The steps of the gamma voltage generating module receiving the gamma reference voltage and dividing the gamma reference voltage to generate gamma voltages of various levels corresponding to the duration of the field blanking period include: The gamma voltage generating module divides the first gamma reference voltage and the second gamma reference voltage and then outputs the corresponding gamma voltages of each level.

9. A display device, characterized in that: The display device comprises: A display panel, used for displaying frame images; A driving circuit is electrically connected to the display panel and is used to drive the display panel; wherein the driving circuit is the driving circuit described in any one of claims 1-3, and the driving method of the driving circuit to drive the display panel is the driving method described in any one of claims 4-8.

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