CN114765014B - Display panel, driving method and driving device thereof - Google Patents
Display panel, driving method and driving device thereof Download PDFInfo
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- CN114765014B CN114765014B CN202110033008.8A CN202110033008A CN114765014B CN 114765014 B CN114765014 B CN 114765014B CN 202110033008 A CN202110033008 A CN 202110033008A CN 114765014 B CN114765014 B CN 114765014B
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
- G09G3/30—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels
- G09G3/32—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED]
- G09G3/3208—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED]
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G2320/00—Control of display operating conditions
- G09G2320/06—Adjustment of display parameters
- G09G2320/0626—Adjustment of display parameters for control of overall brightness
Abstract
The invention relates to the technical field of display, and provides a display panel, a driving method and a driving device thereof. The driving method comprises the following steps: detecting that the display panel enters a variable refresh rate mode; determining a target refresh rate range according to the refresh rate range of the variable refresh rate mode, wherein a minimum value of the self-refresh rate range of the target refresh rate range is taken to a target threshold value; judging whether the refresh rate of the current frame is in the target refresh rate range according to the frame signal of the current frame; if so, the first level voltage of the scanning signal in the blanking stage of the current frame is adjusted, so that the voltage difference between the first level voltage of the scanning signal in the blanking stage and the second level voltage of the scanning signal is larger than the voltage difference between the first level voltage of the scanning signal in the effective stage of the current frame and the second level voltage of the scanning signal. The invention can reduce the display brightness of the display panel under the low refresh rate, keep the display brightness consistent with the display brightness under the high refresh rate, improve the brightness change problem caused by the refresh rate change and optimize the user experience.
Description
Technical Field
The present invention relates to the field of display technologies, and in particular, to a display panel, and a driving method and a driving device thereof.
Background
At present, a plurality of display panels are provided with a variable refresh rate technology, so that the refresh rate can be changed under different application scenes, and the power consumption is saved. However, when the refresh rate of the display panel is changed, the brightness thereof is also changed.
Fig. 1 shows a brightness variation curve of a display panel at 32 gray levels, the refresh rate of which is switched from 30Hz to 60Hz, as measured by an optical measuring tool. In the pixel circuit of the display panel, the brightness at the beginning of each frame is low at low gray scale due to transistor leakage and hysteresis effects. The integral of the luminance curve is the average luminous luminance of the display panel. In fig. 1, the first region 110 shows the brightness of the display panel at a refresh rate of 30Hz, and the second region 120 shows the brightness of the display panel at a refresh rate of 60 Hz. As can be seen from fig. 1, the average light emission luminance of the display panel at 30Hz is greater than the average light emission luminance at 60Hz at 32 gray scales.
The human eyes are very sensitive to the brightness change of low gray level, so that when the refresh rate of the display panel is changed at low gray level, the brightness change is easily captured by the human eyes, so that the user experience is influenced, the eye fatigue is accelerated, and the human eyes are damaged.
It should be noted that the information disclosed in the above background section is only for enhancing understanding of the background of the invention and thus may include information that does not form the prior art that is already known to those of ordinary skill in the art.
Disclosure of Invention
The invention provides a display panel, a driving method and a driving device thereof, which reduce the display brightness under a low refresh rate through the adjustment of the level voltage of a scanning signal, so that the display brightness is consistent with the display brightness under a high refresh rate, thereby improving the brightness change problem caused by the change of the refresh rate and optimizing the user experience.
One aspect of the present invention provides a driving method of a display panel, including: detecting that the display panel enters a variable refresh rate mode; determining a target refresh rate range according to the refresh rate range of the variable refresh rate mode, wherein the target refresh rate range is taken from a minimum value of the refresh rate range to a target threshold value; judging whether the refresh rate of a current frame is in the target refresh rate range or not according to a frame signal of the current frame; if so, adjusting the first level voltage of the scanning signal in the blanking stage of the current frame, so that the voltage difference between the first level voltage and the second level voltage of the scanning signal in the blanking stage is larger than the voltage difference between the first level voltage and the second level voltage of the scanning signal in the effective stage of the current frame.
In some embodiments, when the scan signal is at the first level voltage, in the pixel circuit of the display panel, except for the driving transistor for driving the light emitting element of the pixel circuit to emit light, the remaining transistors are in an off state; the scanning signal acts on the control end of the residual transistor, and the adjusted first level voltage of the scanning signal reduces the current flowing through the light emitting element through parasitic capacitance generated by the residual transistor in the pixel circuit in the blanking stage.
In some embodiments, the transistors in the pixel circuit are PMOS transistors, the first level voltage of the scan signal is a high level voltage VGH, and the second level voltage of the scan signal is a low level voltage VGL; the adjusting the first level voltage of the scanning signal in the blanking stage of the current frame includes: the high level voltage VGH of the scan signal in the blanking period is increased.
In some embodiments, the transistors in the pixel circuit are NMOS transistors, the first level voltage of the scan signal is a low level voltage VGL, and the second level voltage of the scan signal is a high level voltage VGH; the adjusting the first level voltage of the scanning signal in the blanking stage of the current frame includes: the low level voltage VGL of the scan signal in the blanking period is reduced.
In some embodiments, the pixel circuit of each pixel of the display panel includes: a first transistor, a first end of which is coupled to the initialization voltage end, a second end of which is coupled to the first node, and a control end of which receives a first scan signal; a first end of the second transistor is coupled with the data line, a second end of the second transistor is coupled with the first node, and a control end of the second transistor receives a second scanning signal; a third transistor having a first end coupled to the anode of the light emitting element, a second end coupled to the initialization voltage end, and a control end receiving a third scan signal; a driving transistor, a first end of which is coupled with the anode of the light emitting element, a second end of which is coupled with the anode power end, and a control end of which is coupled with the first node; a storage capacitor coupled between the first node and the anode power supply terminal; when the scan signal is at a first level voltage, the driving transistor is turned on, and the first transistor, the second transistor, and the third transistor are turned off.
In some embodiments, the adjusting the first level voltage of the scan signal in the blanking phase of the current frame includes: and adjusting first level voltages of the first scanning signal, the second scanning signal and the third scanning signal in the blanking stage, so that the first scanning signal, the second scanning signal and the third scanning signal are adjusted simultaneously when the current frame enters the blanking stage.
In some embodiments, the operation of the pixel circuit during the active phase includes: a first reset stage in which the first transistor is turned on in response to a second level voltage of the first scan signal, and an initialization voltage signal of the initialization voltage terminal initializes the control terminal of the driving transistor and the storage capacitor; a charging stage in which the second transistor is turned on in response to a second level voltage of the second scan signal, and a data voltage signal of the data line charges a control terminal of the driving transistor and the storage capacitor; a second reset stage in which the third transistor is turned on in response to a second level voltage of the third scan signal, the initialization voltage signal initializing an anode of the light emitting element; and in the display stage, the driving transistor is conducted to drive the light-emitting element to emit light.
In some embodiments, after the determining whether the refresh rate of the current frame is within the target refresh rate range, the method further includes: if not, keeping the first level voltage of the scanning signal in the blanking stage equal to the first level voltage of the scanning signal in the effective stage.
Another aspect of the present invention provides a driving apparatus for a display panel, for implementing the driving method according to any of the above embodiments, the driving apparatus comprising: the detection unit is configured to detect that the display panel enters a variable refresh rate mode and trigger the determination unit; a determining unit configured to determine a target refresh rate range according to a refresh rate range of the variable refresh rate mode, the target refresh rate range taking a target threshold from a minimum value of the refresh rate range; the judging unit is configured to judge whether the refresh rate of the current frame is within the target refresh rate range according to the frame signal of the current frame, and if so, the adjusting unit is triggered; the adjusting unit is configured to adjust a first level voltage of the scanning signal in a blanking stage of the current frame, so that a voltage difference between the first level voltage and a second level voltage of the scanning signal in the blanking stage is larger than a voltage difference between the first level voltage and the second level voltage of the scanning signal in an effective stage of the current frame.
A further aspect of the present invention provides a display panel provided with the driving device of the above embodiment.
Compared with the prior art, the invention has the beneficial effects that at least:
when the display panel is detected to enter a variable refresh rate mode, determining a low refresh rate range of brightness to be adjusted; when the refresh rate of the current frame is in the low refresh rate range, the level voltage of the scanning signal in the blanking stage of the current frame is adjusted, so that the level voltage amplitude of the scanning signal in the blanking stage is larger than that in the effective stage; due to the existence of various parasitic capacitances in the pixel circuit, the amplitude of the level voltage of the scanning signal is increased in the blanking stage, so that the working point of the light-emitting element is shifted, the current flowing through the light-emitting element is reduced, the display brightness of the display panel under the low refresh rate is reduced, the display brightness of the display panel is consistent with the display brightness under the high refresh rate, the brightness change problem caused by the change of the refresh rate is improved, and the user experience is optimized.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention. It is evident that the drawings in the following description are only some embodiments of the present invention and that other drawings may be obtained from these drawings without inventive effort for a person of ordinary skill in the art.
FIG. 1 shows a luminance variation curve of a conventional display panel in which a refresh rate is switched from 30Hz to 60Hz at 32 gray levels;
fig. 2 is a schematic diagram showing steps of a driving method of a display panel according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a pixel circuit of each pixel of a display panel according to an embodiment of the present invention;
FIG. 4 is a timing diagram of a scan signal of a current frame according to an embodiment of the present invention;
fig. 5 is a schematic diagram showing the brightness variation of the display panel before and after the adjustment of the high level voltage VGH of the scan signal, and the brightness variation of the display panel according to the embodiment of the invention;
fig. 6 is a schematic block diagram of a driving apparatus of a display panel according to an embodiment of the invention.
Detailed Description
Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the example embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and thus a repetitive description thereof will be omitted.
Furthermore, the drawings are merely schematic illustrations of the present disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and thus a repetitive description thereof will be omitted. Some of the block diagrams shown in the figures are functional entities and do not necessarily correspond to physically or logically separate entities. These functional entities may be implemented in software or in one or more hardware modules or integrated circuits or in different networks and/or processor devices and/or microcontroller devices.
The step numbers in the following embodiments are used to represent different execution contents, and the execution order between steps is not strictly limited. The use of the terms "first," "second," and the like in the description herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. It should be noted that, without conflict, the embodiments of the present invention and features in different embodiments may be combined with each other.
Fig. 2 shows main steps of a driving method of a display panel in the embodiment, and referring to fig. 2, the driving method of the display panel in the embodiment includes:
in step S210, it is detected that the display panel enters a variable refresh rate mode.
Specifically, each frame of signal of the display panel can be detected through a time sequence controller of the display panel, whether the display panel enters a variable refresh rate mode currently is judged, and the subsequent adjustment of the display brightness of the display panel under the condition of frequency conversion is realized.
In step S220, a target refresh rate range is determined according to the refresh rate range of the variable refresh rate mode, and a minimum value of the self-refresh rate range of the target refresh rate range is taken to a target threshold value.
Since the display brightness of the display panel at the low refresh rate is higher than the display brightness at the high refresh rate, a low refresh rate range of the brightness to be adjusted is determined, and the display brightness of the display panel in the low refresh rate range is adjusted later. The target threshold may be preset as desired, and may be a specific refresh rate value, or a proportional value. For example, in one example, the variable refresh rate mode has a refresh rate range of 60Hz to 25Hz and the target threshold value is 40Hz, and the determined target refresh rate range is 25Hz to 40Hz. As another example, in one example, the variable refresh rate mode has a refresh rate range of 60Hz to 25Hz, the target threshold is 80% of the maximum refresh rate in the refresh rate range, and the determined target refresh rate range is 25Hz to 48Hz.
In step S230, it is determined whether the refresh rate of the current frame is within the target refresh rate range according to the frame signal of the current frame.
In step S240, when the refresh rate of the current frame is determined to be within the target refresh rate range, the first level voltage of the scan signal in the blanking stage of the current frame is adjusted so that the voltage difference between the first level voltage and the second level voltage of the scan signal in the blanking stage is greater than the voltage difference between the first level voltage and the second level voltage of the scan signal in the active stage of the current frame.
When the refresh rate of the current frame is in the low refresh rate range, the level voltage of the scanning signal in the blanking stage of the current frame is adjusted so that the level voltage amplitude of the scanning signal in the blanking stage is larger than that in the effective stage. Due to the existence of various parasitic capacitances in the pixel circuit, the amplitude of the level voltage of the scanning signal is increased in the blanking stage, so that the working point of the light-emitting element is shifted, the current flowing through the light-emitting element is reduced, the display brightness of the display panel under the low refresh rate is reduced, the display brightness of the display panel is consistent with the display brightness under the high refresh rate, the brightness change problem caused by the change of the refresh rate is improved, and the user experience is optimized.
When the scanning signal is at the first level voltage, in the pixel circuit of the display panel, the rest transistors are in an off state except that the driving transistor for driving the light emitting element of the pixel circuit to emit light is in an on state; the scanning signal acts on the control end of the residual transistor, and in the blanking stage, the adjusted first level voltage of the scanning signal reduces the current flowing through the light emitting element through parasitic capacitance generated by the residual transistor in the pixel circuit.
In a specific example, when the transistors in the pixel circuits of the display panel are PMOS transistors, the first level voltage of the scan signal is the high level voltage VGH, and the second level voltage of the scan signal is the low level voltage VGL; the first level voltage of the scanning signal in the blanking stage of the current frame is adjusted, specifically, the high level voltage VGH of the scanning signal in the blanking stage is increased, so that the high level voltage VGH of the scanning signal in the blanking stage of the current frame is higher than the high level voltage VGH of the scanning signal in the effective stage of the current frame, and therefore the display brightness of the display panel is reduced in the blanking stage of the current frame, and the overall display brightness of the display panel in the current frame is reduced.
In a specific example, when transistors in the pixel circuit of the display panel are all NMOS transistors, the first level voltage of the scan signal is the low level voltage VGL, and the second level voltage of the scan signal is the high level voltage VGH; the adjustment of the first level voltage of the scanning signal in the blanking stage of the current frame specifically means that the low level voltage VGL of the scanning signal in the blanking stage is reduced, so that the low level voltage VGL of the scanning signal in the blanking stage of the current frame is lower than the low level voltage VGL of the scanning signal in the effective stage of the current frame, and therefore the display brightness of the display panel is reduced in the blanking stage of the current frame, and the overall display brightness of the display panel in the current frame is reduced.
The principle of the driving method of the present invention will be described in detail with reference to the pixel circuit of the display panel, taking the PMOS transistor as an example of the transistor in the pixel circuit. The invention is not limited to the use of PMOS transistors.
Fig. 3 shows a pixel circuit of each pixel of the display panel according to the embodiment, and referring to fig. 3, the pixel circuit of one pixel of the display panel mainly includes: first transistor T 1 A first terminal coupled to the initialization voltage terminal VINT and a second terminal coupled to the first node N 1 The control end receives the first scanning signal S n-1 The method comprises the steps of carrying out a first treatment on the surface of the Second transistor T 2 A first terminal coupled to the DATA line DATA line and a second terminal coupled to the first node N 1 The control end receives the second scanning signal S n The method comprises the steps of carrying out a first treatment on the surface of the Third transistor T 3 A first terminal coupled to the anode of the light emitting element OLED, a second terminal coupled to the initialization voltage terminal VINT, and a control terminal receiving the third scan signal S n+1 The method comprises the steps of carrying out a first treatment on the surface of the Drive transistor T d A first terminal coupled to the anode of the light emitting element OLED, a second terminal coupled to the anode power terminal ELVDD, and a control terminal coupled to the first node N 1 The cathode of the light emitting element OLED is coupled with the cathode power supply end ELVSS; storage capacitor C st Coupled to the first node N 1 And the anode power supply terminal ELVDD.
In this embodiment, the first level voltage of the scan signal in the blanking period of the current frame is adjusted to make the current frame enter the blanking period n-1 Second scanning signal S n And a third scan signal S n+1 The high level voltage VGH of (2) increases at the same time. First scanning signal S n-1 Second scanning signal S n And a third scan signal S n+1 The respective increasing magnitudes of the high-level voltages VGH of (a) may be the same or different, and the first scan signal S may be specifically selected n-1 Second scanning signal S n And a third scan signal S n+1 The circuit characteristics of the transistors to be operated are determined. In a specific example, the first scanning signal S can be caused to n-1 Second scanning signal S n And a third scan signal S n+1 The high level voltages VGH of (2) are respectively increased by a preset value in the blanking period of the current frame, and the preset value may have a certain range, for example, 0.1V to 5V.
In addition, the adjustment amplitude of the high-level voltage VGH is also related to the refresh rate, and the lower the refresh rate is, the higher the display brightness is, the larger the brightness value to be reduced is, so the larger the adjustment amplitude of the high-level voltage VGH is, so as to achieve the effect of changing different brightness under different frequencies by adjusting the high-level voltage VGH.
The Blanking period (Blanking) is a display interval period of two frames, that is, an interval period from the end of one frame to the start of the next frame, and the Blanking period of the current frame is located between the active period of the current frame and the active period of the next frame of the current frame. The frame signal of each frame includes parameter information related to a blanking period, and the length of the blanking period is sent by a graphics chip (Graphics Processing Unit, GPU for short) of the display panel, for example, the length of the blanking period occupies 4% of the period of one frame of the frame. The refresh rate of the frame signal is different, and the length of the corresponding blanking period is also different. The blanking period of the frame signal of low refresh rate is long and the blanking period of high refresh rate is short.
Fig. 4 illustrates the timing of the scan signal of the current frame, and referring to fig. 4, the entire phase of the frame period of the current frame includes an active phase 410 and a blanking phase 420. As shown in connection with fig. 3 and 4, the operation of the pixel circuit during the active phase 410 of the current frame includes:
first reset stage, first transistor T 1 In response to the first scanning signal S n-1 Is turned on by the low level voltage VGL of the voltage source voltage terminal VINT, and initializes the driving transistor T by the initialization voltage signal of the initialization voltage terminal VINT d Control terminal of (C) and storage capacitor C st . Thereafter the first transistor T 1 At the first scanning signal S n-1 Is turned off by the high level voltage VGH of (2).
A charging stage, a second transistor T 2 In response to the second scanning signal S n Is turned on by the low level voltage VGL of the DATA line DATA line, and the DATA voltage signal of the DATA line goes to the driving transistor T d Control terminal of (C) and storage capacitor C st Charging; storage capacitor C st The stored voltage is V g . Thereafter the second transistor T 2 Turned off by the high level voltage VGH of the second scan signal Sn.
Second reset stage, third transistor T 3 In response to the third scanning signal S n+1 Is turned on by the low level voltage VGL of (a), and the initialization voltage signal initializes the anode of the light emitting element OLED. Thereafter, the third transistor T 3 In the third scanning signal S n+1 Is turned off by the high level voltage VGH of (2).
In the display stage, the transistor T is driven d At the first node N 1 Is conducted under the action of the voltage to drive the light-emitting element OLED to emit light, and the current flowing through the light-emitting element OLED is I OLED 。
Further, in the blanking phase, the first transistor T 1 Second transistor T 2 And a third transistor T 3 Respectively at the first scanning signals S n-1 Second scanning signal S n And a third scan signal S n+1 Continues to be turned off under the action of the increased high-level voltage VGH' and reduces the current flowing through the light emitting element OLED to I OLED Thereby reducing the display brightness in the blanking period.
Of course, the high level voltage of each scanning signal is adjusted in the blanking stage of the current frame, so that the high level voltage of each scanning signal is increased to VGH'; in the effective stage of the next frame, the high level voltage of each scanning signal needs to be adjusted back to VGH; and determining whether the blanking stage of the next frame needs to adjust the high level voltage of each scanning signal according to whether the refresh rate of the next frame is in the target refresh rate range. That is, in the effective stage of each frame, the high level voltage of each scanning signal remains the same to achieve the stability of the overall display effect; and in the blanking stage of every frame, according to the refresh rate of frame it is determined whether to regulate high-level voltage of every scanning signal.
By increasing the high level voltage VGH of the scanning signal in the blanking stage, the current flowing through the light emitting element OLED is reduced to I OLED Mainly because, in the pixel circuit, the first transistor T is formed between the transistor and the line (e.g. the second transistor T 1 Second transistor T 2 Third transistor T 3 And storage capacitor C st Between) various parasitic capacitances, changing the magnitude of the high-level voltage VGH during the blanking period will directly affect the first transistor T 1 Second transistor T 2 Third transistor T 3 Operating point and conduction conditions of (1) to cause V g Changes in (V) g For storing capacitor C st Voltage stored in memory), directly leading to the driving transistor T d An operating point is shifted so that a current I flows through the light emitting element OLED OLED The size of (c) is changed, and thus the luminance of the light emitting element OLED is changed.
Specifically, in a practical application scenario, when the light emitting element OLED emits light, the first transistor T 1 Second transistor T 2 And a third transistor T 3 Cut-off, driving transistor T d Saturated, current I flowing through the light emitting element OLED OLED Is subjected to V gs (V gs ＝V g ELVDD), the saturation region current formula according to the ideal state is:
I OLED ＝1/2·μ p ·C OX ·W/L·(V gs -V th ) 2
＝1/2·μ p ·C OX ·W/L·(V data +V th -ELVDD-V th ) 2
＝1/2·μ p ·C OX ·W/L·(V data -ELVDD) 2
wherein mu p 、C OX And W/L are both the same as the driving transistor T d Related device parameters, it can be seen that the current I flowing through the light emitting element OLED OLED Receiving data voltage V data Regulation of the anode voltage ELVDD (from the data line) and the anode power supply terminal.
For the first scanning signal S in the blanking stage n-1 Second scanning signal S n And a third scan signal S n+1 The high level voltage VGH of (1) is adjusted to directly affect the first transistor T 1 Second transistor T 2 And a third transistor T 3 Gate voltage of the off state of the first transistor T 1 Second transistor T 2 And a third transistor T 3 Parasitic capacitance (gate capacitance and depletion layer capacitance) exist, and the parasitic capacitance directly affects the first transistor T 1 Second transistor T 2 And a third transistor T 3 Is not limited to the above-mentioned structure.
When the light emitting element OLED emits light, V g ≈V data +V th ，V th Is the threshold voltage. At this time, although the first transistor T 1 Second transistor T 2 And a third transistor T 3 All the devices are turned off, but parasitic resistances exist at the front ends of the source drain region and the shallow source drain region, ohmic contact resistances exist between the source drain region and the metal, and the parasitic resistances bring certain influence to the devices. With a first transistor T 1 For example, if the first scanning signal S is increased n-1 Can be at the first transistor T 1 Forms a deeper depletion layer to lower the first transistor T 1 Thereby reducing the voltage division of parasitic resistance and raising V data And V th Thereby enabling the current I flowing through the light-emitting element OLED OLED Reduced, eventually resulting in a reduction in display brightness.
Fig. 5 shows a comparison between a luminance change of a conventional display panel and a luminance change of the display panel according to an embodiment of the present invention before and after the high level voltage VGH adjustment of the scan signal. Referring to fig. 5, a first brightness variation curve 510 corresponds to a conventional display panel, and a second brightness variation curve 520 corresponds to a display panel according to an embodiment of the present invention, in which the high level voltage VGH of the scan signal is changed in the blanking period of the frames with low refresh rate, so that the brightness of the frames with low refresh rate is reduced in the blanking period, and the average brightness at all refresh rates is kept consistent. Further, when the display panel is switched between different refresh rates, the brightness difference can be reduced, and the flicker phenomenon visible to the human eye can be reduced.
According to the first transistor T 1 Second transistor T 2 And a third transistor T 3 A first scan signal S initially set n-1 Second scanning signal S n And a third scan signal S n+1 The high level voltage VGH of (2) is 6.5V, and the display luminance of the display panel is 418.9nit at a refresh rate of 30Hz at 32 gray levels. In the blanking stage, the first scan signal S is increased n-1 Second scanning signal S n And a third scan signal S n+1 The brightness of the display panel is shown in the following table:
| VGH/V | brightness/nit |
| 6.5 | 418.9000 |
| 8.5 | 396.3000 |
| 8 | 401.9000 |
| 7.5 | 410.0000 |
| 7 | 414.5000 |
It can be seen that increasing the high level voltage VGH in the blanking stage can achieve a decrease in luminance of the display panel in the blanking stage, and thus a decrease in luminance in the entire frame stage.
Further, when the frame signal of the current frame is judged not to be in the target refresh rate range, it is explained that the refresh rate of the current frame is higher, and the level voltage of the scanning signal is not required to be adjusted, so that the first level voltage of the scanning signal in the blanking stage is kept equal to the first level voltage of the scanning signal in the effective stage.
Of course, in other embodiments, the level voltage of the scanning signal may be adjusted in the blanking stage of all frames, where the adjustment amplitude of the frames with high refresh rate is small and the adjustment amplitude of the frames with low refresh rate is large, so that the display brightness of all frames after adjustment is kept consistent.
In summary, by adopting the driving method of any embodiment of the present invention, the level voltage of the scanning signal is adjusted in the blanking stage of the frame with a low refresh rate, so as to reduce the current flowing through the light emitting element in the blanking stage, thereby reducing the display brightness of the display panel with a low refresh rate, keeping the display brightness consistent with the display brightness with a high refresh rate, improving the brightness change problem caused by the refresh rate change, and optimizing the user experience.
The embodiment of the invention also provides a driving device of the display panel, which can be used for realizing the driving method described in any embodiment. Fig. 6 shows main modules of the driving apparatus in the embodiment, and referring to fig. 6, the driving apparatus 600 in this embodiment includes: the detecting unit 610 is configured to detect that the display panel enters a variable refresh rate mode, and trigger the determining unit; a determining unit 620 configured to determine a target refresh rate range according to the refresh rate range of the variable refresh rate mode, wherein a minimum value of the self-refresh rate range of the target refresh rate range is taken to a target threshold value; the judging unit 630 is configured to judge whether the refresh rate of the current frame is within the target refresh rate range according to the frame signal of the current frame, if so, the adjusting unit is triggered; the adjusting unit 640 is configured to adjust the first level voltage of the scanning signal in the blanking period of the current frame, so that the voltage difference between the first level voltage and the second level voltage of the scanning signal in the blanking period is greater than the voltage difference between the first level voltage and the second level voltage of the scanning signal in the active period of the current frame.
The detecting unit 610, the determining unit 620, the judging unit 630 and the adjusting unit 640 may be respectively disposed in the existing devices of the display panel, for example, the detecting unit 610, the determining unit 620 and the judging unit 630 are disposed in the timing controller, and the adjusting unit is disposed in the driving control chip. The specific principle of each unit module in the driving device can be referred to the description of any driving method embodiment described above, and will not be repeated here.
The embodiment of the invention also provides a display panel which is provided with the driving device and is controlled by the driving method to perform display luminescence.
In summary, the display panel, the driving method and the driving device thereof, provided by the invention, realize the reduction of the current flowing through the light-emitting element in the blanking stage by adjusting the level voltage of the scanning signal in the blanking stage of the frame with low refresh rate, thereby reducing the display brightness of the display panel under the low refresh rate, keeping the same with the display brightness under the high refresh rate, improving the brightness change problem caused by the change of the refresh rate, and optimizing the user experience.
The foregoing is a further detailed description of the invention in connection with the preferred embodiments, and it is not intended that the invention be limited to the specific embodiments described. It will be apparent to those skilled in the art that several simple deductions or substitutions may be made without departing from the spirit of the invention, and these should be considered to be within the scope of the invention.
Claims (9)
1. A driving method of a display panel, comprising:
detecting that the display panel enters a variable refresh rate mode;
determining a target refresh rate range according to the refresh rate range of the variable refresh rate mode, wherein the target refresh rate range is taken from a minimum value of the refresh rate range to a target threshold value;
judging whether the refresh rate of a current frame is in the target refresh rate range or not according to a frame signal of the current frame;
if yes, adjusting a first level voltage of a scanning signal in a blanking stage of the current frame, so that a voltage difference between the first level voltage of the scanning signal in the blanking stage and a second level voltage of the scanning signal is larger than a voltage difference between the first level voltage of the scanning signal in an effective stage of the current frame and the second level voltage of the scanning signal;
when the scanning signal is at a first level voltage, in a pixel circuit of the display panel, except for a driving transistor for driving a light-emitting element of the pixel circuit to emit light, the driving transistor is in an on state, and the rest transistors are in an off state;
the scanning signal acts on the control end of the residual transistor, and the adjusted first level voltage of the scanning signal reduces the current flowing through the light emitting element through parasitic capacitance generated by the residual transistor in the pixel circuit in the blanking stage.
2. The driving method as claimed in claim 1, wherein the transistors in the pixel circuit are PMOS transistors, the first level voltage of the scan signal is a high level voltage VGH, and the second level voltage of the scan signal is a low level voltage VGL;
the adjusting the first level voltage of the scanning signal in the blanking stage of the current frame includes:
the high level voltage VGH of the scan signal in the blanking period is increased.
3. The driving method as claimed in claim 1, wherein transistors in the pixel circuit are NMOS transistors, a first level voltage of the scan signal is a low level voltage VGL, and a second level voltage of the scan signal is a high level voltage VGH;
the adjusting the first level voltage of the scanning signal in the blanking stage of the current frame includes:
the low level voltage VGL of the scan signal in the blanking period is reduced.
4. The driving method according to claim 1, wherein a pixel circuit of each pixel of the display panel includes:
a first transistor, a first end of which is coupled to the initialization voltage end, a second end of which is coupled to the first node, and a control end of which receives a first scan signal;
a first end of the second transistor is coupled with the data line, a second end of the second transistor is coupled with the first node, and a control end of the second transistor receives a second scanning signal;
a third transistor having a first end coupled to the anode of the light emitting element, a second end coupled to the initialization voltage end, and a control end receiving a third scan signal;
a driving transistor, a first end of which is coupled with the anode of the light emitting element, a second end of which is coupled with the anode power end, and a control end of which is coupled with the first node;
a storage capacitor coupled between the first node and the anode power supply terminal;
when the scan signal is at a first level voltage, the driving transistor is turned on, and the first transistor, the second transistor, and the third transistor are turned off.
5. The driving method of claim 4, wherein adjusting the first level voltage of the scan signal in the blanking period of the current frame comprises:
and adjusting first level voltages of the first scanning signal, the second scanning signal and the third scanning signal in the blanking stage, so that the first scanning signal, the second scanning signal and the third scanning signal are adjusted simultaneously when the current frame enters the blanking stage.
6. The driving method as claimed in claim 4, wherein the operation of the pixel circuit in the active phase comprises:
a first reset stage in which the first transistor is turned on in response to a second level voltage of the first scan signal, and an initialization voltage signal of the initialization voltage terminal initializes the control terminal of the driving transistor and the storage capacitor;
a charging stage in which the second transistor is turned on in response to a second level voltage of the second scan signal, and a data voltage signal of the data line charges a control terminal of the driving transistor and the storage capacitor;
a second reset stage in which the third transistor is turned on in response to a second level voltage of the third scan signal, the initialization voltage signal initializing an anode of the light emitting element;
and in the display stage, the driving transistor is conducted to drive the light-emitting element to emit light.
7. The driving method of claim 1, wherein determining whether the refresh rate of the current frame is within the target refresh rate range further comprises:
if not, keeping the first level voltage of the scanning signal in the blanking stage equal to the first level voltage of the scanning signal in the effective stage.
8. A driving device for a display panel, characterized in that it is used for realizing the driving method according to any one of claims 1 to 7, said driving device comprising:
the detection unit is configured to detect that the display panel enters a variable refresh rate mode and trigger the determination unit;
a determining unit configured to determine a target refresh rate range according to a refresh rate range of the variable refresh rate mode, the target refresh rate range taking a target threshold from a minimum value of the refresh rate range;
the judging unit is configured to judge whether the refresh rate of the current frame is within the target refresh rate range according to the frame signal of the current frame, and if so, the adjusting unit is triggered;
the adjusting unit is configured to adjust a first level voltage of the scanning signal in a blanking stage of the current frame, so that a voltage difference between the first level voltage and a second level voltage of the scanning signal in the blanking stage is larger than a voltage difference between the first level voltage and the second level voltage of the scanning signal in an effective stage of the current frame.
9. A display panel, characterized in that the display panel is provided with a driving device as claimed in claim 8.
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| CN117437880A (en) * | 2023-12-20 | 2024-01-23 | 维信诺科技股份有限公司 | Display device and control method thereof |
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