Display device and display driving method

Abstract

The present application belongs to the field of display driving technology, and specifically relates to a display device and a display driving method. The display device includes a display panel and a driving chip. The display panel includes: K row partitions, each row partition includes an anode reset node and at least one row of pixel driving circuits; each of the pixel driving circuits includes at least a light emitting diode and an anode reset terminal; the driving chip includes K reset voltage output terminals, and the reset voltage output terminals are connected to the anode reset nodes in a one-to-one correspondence; the driving chip is used to obtain a target anode reset voltage corresponding to each row partition, and output the target anode reset voltage to the anode reset node of the corresponding row partition through the reset voltage output terminal, so that the target anode reset voltage compensates the anode voltage of the light emitting diode in the light emitting stage, and at the same time solves the problem of voltage drop and display delay between different row partitions, and improves the uniformity of display brightness.

Description

Technical Field

[0001] The present disclosure belongs to the field of display driving technology, and in particular relates to a display device and a display driving method. Background Art

[0002] Organic light-emitting diodes (OLEDs), as a current-type light-emitting device, have been increasingly used in high-performance displays. Based on device characteristics and display principles, flexible or rigid substrate circuits have line resistance, which causes uneven distribution of the driving voltage VDD inside the display panel. In addition, due to the film-forming process, the light-emitting layer can be regarded as a capacitor in parallel with the light-emitting diode, which causes voltage charging time for OLEDs during the light-emitting stage.

[0003] Therefore, in the case of low gray scale, high refresh rate and / or uneven driving voltage distribution, the anode voltage of the OLED is unstable, resulting in uneven display brightness of the picture. Summary of the invention

[0004] The present application provides a display device and a display driving method to solve the problem of uneven display brightness.

[0005] In a first aspect, the present application provides a display device, comprising a display panel and a driver chip, wherein the display panel comprises: K row partitions, each row partition comprising an anode reset node and at least one row of pixel driving circuits; each of the pixel driving circuits comprises at least a light-emitting diode and an anode reset terminal; in the row partitions: the anode reset node is connected to the anode reset terminal of each pixel driving circuit; wherein K is a positive integer greater than 1; the driver chip comprises K reset voltage output terminals, and the reset voltage output terminals are connected to the anode reset nodes in a one-to-one correspondence; the driver chip is used to obtain a target anode reset voltage corresponding to each row partition, and output the target anode reset voltage to the anode reset node of the corresponding row partition through the reset voltage output terminal, so that the target anode reset voltage compensates the anode voltage of the light-emitting diode in the light-emitting stage.

[0006] Optionally, the pixel driving circuit also includes: a driving transistor, an anode reset transistor, a data writing transistor, a first control transistor, a second control transistor and a storage capacitor; the control end of the driving transistor and the first end of the storage capacitor are respectively connected to the first node, the first end of the driving transistor is connected to the first end of the first control transistor, and the second end of the driving transistor is connected to the first end of the second control transistor; the second end of the first control transistor and the second end of the storage capacitor are respectively electrically connected to the power line, the second end of the second control transistor and the anode of the light-emitting diode are respectively connected to the second node, and the control end of the first control transistor and the control end of the second control transistor are respectively electrically connected to the light-emitting control line; the control end of the data writing transistor is electrically connected to the first scan line, the first end of the data writing transistor is electrically connected to the data line, and the second end of the data writing transistor is connected to the first end of the driving transistor; the control end of the anode reset transistor is electrically connected to the first scan line, the first end of the anode reset transistor is connected to the anode reset node, the second end of the anode reset transistor is connected to the second node, and the cathode of the light-emitting diode is grounded.

[0007] Optionally, the pixel driving circuit also includes: an initialization transistor and a compensation transistor; the control end of the initialization transistor is electrically connected to the second scan line, the first end of the initialization transistor is electrically connected to the initialization signal line, and the second end of the initialization transistor is connected to the first node; the control end of the compensation transistor is electrically connected to the third scan line, the first end of the compensation transistor is connected to the first node, and the second end of the compensation transistor is connected to the second end of the driving transistor.

[0008] Optionally, the data writing transistor, the anode reset transistor, the first control transistor and the second control transistor are P-type MOS transistors, and the initialization transistor, the compensation transistor and the driving transistor are N-type MOS transistors.

[0009] In a second aspect, the present application provides a display driving method, which is applied to a display device, and the display driving method includes: in a test phase, obtaining an actual brightness picture of a display panel when displaying a preset brightness picture; according to the brightness difference between the preset brightness picture and the actual brightness picture, or the brightness difference between the local brightness and the overall picture, obtaining a target anode reset voltage corresponding to each row partition, and writing all target anode reset voltages into a driver chip; in a display phase, controlling K reset voltage output terminals of the driver chip to output corresponding target anode reset voltages to the anode reset nodes of the corresponding row partitions, so that the target anode reset voltage compensates for the anode voltage of the light-emitting diode in the light-emitting phase.

[0010] Optionally, according to the brightness difference between the preset brightness picture and the actual brightness picture, or the brightness difference between the local brightness and the overall picture, the target anode reset voltage corresponding to each row partition is obtained, including: setting the same initial anode reset voltage for each row partition; determining whether there is a brightness difference in the actual brightness picture; when there is a brightness difference in the actual brightness picture, obtaining a normal target voltage of a normal brightness display area, an abnormal target voltage of an abnormal brightness display area, and at least one target row partition corresponding to the abnormal brightness display area in the actual brightness picture; the normal target voltage and the abnormal target voltage are the anode voltages when the light-emitting diode emits light; according to the difference between the normal target voltage and the abnormal target voltage, a reset compensation value is obtained; the reset compensation value is added to the initial anode reset voltage to obtain the target anode reset voltage corresponding to the at least one target row partition; and the initial anode reset voltage is used as the target anode reset voltage for other row partitions other than the target row partition.

[0011] Optionally, when there is no brightness difference in the actual brightness picture, the initial anode reset voltage is used as the target anode reset voltage corresponding to each row partition.

[0012] Optionally, obtaining a normal target voltage of a normal brightness display area in the actual brightness picture includes: obtaining a driving current corresponding to the normal brightness display area according to a preset current-brightness relationship table; and calculating a normal target voltage of the normal brightness display area according to the driving current, charging time and the initial anode reset voltage.

[0013] Optionally, when the pixel driving circuit includes a driving transistor, an anode reset transistor, a data writing transistor, a first control transistor, a second control transistor, an initialization transistor, a compensation transistor and a storage capacitor, in the display stage, the K reset voltage output terminals of the driving chip are controlled to output the corresponding target anode reset voltage to the anode reset node of the corresponding row partition, so that the target anode reset voltage compensates the anode voltage of the light-emitting diode in the light-emitting stage, including: in the initialization stage, the initialization transistor is controlled to be turned on, and the data writing transistor, the first control transistor, the second control transistor, the compensation transistor and the anode reset transistor are controlled to be turned off, so that the initial voltage output on the initialization signal line is The first node is initialized; at the same time, the K reset voltage output terminals of the driving chip are controlled to output the corresponding target anode reset voltage to the anode reset node of the corresponding row partition; in the data sampling stage, the data writing transistor, the compensation transistor and the anode reset transistor are controlled to be turned on at the same time, the data voltage output on the data line is written to the first node, and the data voltage is used to charge the storage capacitor, and the target anode reset voltage on the anode reset node is written to the second node; in the light emitting stage, the first control transistor and the second control transistor are controlled to be turned on, the target anode reset voltage compensates the anode voltage of the light emitting diode, and the compensated anode voltage drives the light emitting diode to emit light.

[0014] Optionally, determining whether there is a brightness difference in the actual brightness picture includes: graying the actual brightness picture to obtain a grayscale image; dividing the grayscale image into multiple detection areas, and obtaining a grayscale histogram corresponding to each detection area; calculating a grayscale distribution factor corresponding to each detection area based on the grayscale histogram of each detection area; comparing each grayscale distribution factor with a preset threshold, and obtaining whether there is a brightness difference in the actual brightness picture based on the comparison result.

[0015] The technical solution provided by this application has at least the following beneficial effects:

[0016] 1. The present application sets an anode reset terminal for each pixel driving circuit to receive an anode reset voltage, so that the anode reset voltage can not only reset the anode voltage of the light-emitting diode to prevent the anode voltage of the previous frame from affecting the charging voltage of the current frame, but also compensate the anode voltage in the light-emitting stage, solve the problem of display delay in low grayscale or high refresh conditions, and improve the uniformity of display brightness.

[0017] 2. The present application divides the pixel driving circuit arranged in an array in the display panel into multiple independent row partitions, and the anode reset voltage of each row partition is differentially controlled through a driving chip, thereby compensating for the voltage drop problem of the driving voltage between different row partitions, and further improving the uniformity of the display brightness. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings herein are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the specification are used to explain the principles of the present disclosure. Obviously, the accompanying drawings described below are only some embodiments of the present disclosure, and for ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without creative work.

[0019] Figure 1 FIG. 1 is a schematic diagram showing the structure of a pixel driving circuit in the related art.

[0020] Figure 2 Shown is a schematic structural diagram of a display device provided in an embodiment of the present application.

[0021] Figure 3 Shown is a structural schematic diagram of a pixel driving circuit provided in an embodiment of the present application.

[0022] Figure 4 Shown is a timing diagram corresponding to a pixel driving circuit provided in an embodiment of the present application.

[0023] Figure 5 The figure is a schematic diagram of the states of transistors in a pixel driving circuit during an initialization phase provided by an embodiment of the present application.

[0024] Figure 6 FIG. 1 is a schematic diagram showing the states of transistors in a pixel driving circuit during a data sampling phase provided by an embodiment of the present application.

[0025] Figure 7 The figure is a schematic diagram of the state of transistors in a pixel driving circuit provided by an embodiment of the present application during the light emitting stage.

[0026] Figure 8 The figure shows a connection diagram of the anode reset terminal and the corresponding anode reset node in each pixel driving circuit in the same row partition provided by an embodiment of the present application.

[0027] Fig. 9 The figure is a flow chart of a display driving method provided in an embodiment of the present application.

[0028] Fig.10 Shown Fig. 9 Schematic diagram of the process of step S200.

[0029] Fig.11 Shown is a display brightness comparison curve diagram before and after compensation provided by an embodiment of the present application.

[0030] Description of reference numerals:

[0031] 10. Display device;

[0032] 100, display panel; 110, pixel driving circuit; 120, row partition;

[0033] T1, driving transistor; T2, anode reset transistor; T3, data writing transistor; T4, first control transistor; T5, second control transistor; T6, initialization transistor; T7, compensation transistor; Cst, storage capacitor;

[0034] S1, first scan line; S2, second scan line; S3, third scan line; Vint, initialization signal line; ELVDD, power line; EM, light control line; Data, data line; Anode, anode reset terminal; OLED, light emitting diode;

[0035] A, anode reset node; B, reset voltage output terminal; Q, first node; P, second node. DETAILED DESCRIPTION

[0036] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this application will be more comprehensive and complete and fully convey the concept of the example embodiments to those skilled in the art.

[0037] In addition, described feature, structure or characteristic can be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present application. However, those skilled in the art will appreciate that the technical scheme of the present application can be put into practice without one or more of the specific details, or other methods, components, devices, steps, etc. can be adopted. In other cases, known methods, devices, realizations or operations are not shown or described in detail to avoid blurring the various aspects of the application.

[0038] The present application is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the technical features involved in the various embodiments of the present application described below can be combined with each other as long as they do not conflict with each other. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be understood as limiting the present application.

[0039] Here, the technical problems in the background technology are described in detail: Figure 1It is a simple 2T1C pixel driving circuit, where transistor TFT2 provides the corresponding driving current for the OLED device. The light-emitting layer of the OLED device mostly adopts a film-forming process. During the working process, the light-emitting layer can be simply regarded as the parallel connection of the light-emitting diode OLED and the parasitic capacitor Cel. During the light-emitting cycle of the OLED, the transistor TFT2 works in the saturation region, and the driving current formula is as follows:

[0040]

[0041] In formula (1), I represents the driving current, μ n Represents the carrier migration rate of the transistor, C ox Represents the transistor gate capacitance, which is a fixed value. Represents the aspect ratio of the driving transistor, which is also a constant value, V gs Represents the gate-source voltage of the driving transistor, V th Indicates the threshold voltage of the driving transistor, which is a constant value. When the OLED is in the light-emitting cycle, Figure 1 The driving transistor TFT2 in the circuit starts to charge the light-emitting layer. When the charging time is t, the voltage after charging is as shown in formula (2):

[0042] U Cel =I×t / C el (2)

[0043] It can be seen that in the case of lower grayscale or high refresh rate, due to the small values ​​of I and t, insufficient charging may occur, resulting in abnormal voltage uniformity across the capacitor; at the same time, according to the TFT output characteristic curve, when working in the saturation region, the drain-source current I ds (i.e., driving current I) and the drain-source voltage V applied across the TFT ds When the pixel row is far away from the driver chip, the line resistance causes the ELVDD voltage (i.e. V ds and Vgs) decreases, further causing the driving current I to decrease, further causing charging abnormalities; finally, according to the material properties of the light-emitting layer, charging mismatch will lead to light emission delay, resulting in uneven display brightness in OLED display devices.

[0044] In order to solve the above problems, the present application provides a display panel, which specifically includes the following embodiments:

[0045] Figure 2 FIG. 1 is a schematic diagram of a structure of a display device provided in an embodiment of the present application; Figure 2As shown, the display device 10 includes a display panel 100 and a driving chip 200; in this embodiment, the display panel 100 includes K row partitions 120, each row partition 120 includes an anode reset node A and at least one row of pixel driving circuits 110, that is, each row partition 120 includes the same number of columns of pixel driving circuits 110; however, the number of rows of pixel driving circuits 110 included in each row partition 120 may be the same or different, for example, each row partition 120 may include 1 row, 2 rows or 3 rows of pixel driving circuits 110, or the first row partition 120 may include 2 rows, the second row partition 120 may include 3 rows, the fourth row partition 120 may include 2 rows, etc.; wherein, Figure 2 The situation in which five row partitions 120 are shown and each row partition 120 includes two rows of pixel driving circuits 110 is only used as an example. The number of row partitions 120 and the specific number of rows of pixel driving circuits 110 included in each row partition 120 can be adjusted according to the accuracy requirements of the display panel 100 and the longitudinal length of the mura (poor display brightness) area.

[0046] Optionally, each pixel driving circuit 110 includes at least a light emitting diode OLED and an anode reset terminal Anode for resetting the anode voltage of the light emitting diode OLED, and the anode reset terminal Anode in each pixel driving circuit 110 in the same row partition 120 is connected to the corresponding anode reset node A.

[0047] It should be noted that the anode reset terminal Anode in this embodiment is used to receive an anode reset voltage, which can not only reset the anode voltage of the light-emitting diode OLED to prevent the anode voltage of the previous frame from affecting the charging voltage of the current frame, but also compensate for the anode voltage in the light-emitting stage to solve the problem of reduced display brightness or display delay caused by insufficient charging.

[0048] In addition, the anode reset terminal Anode in each pixel driving circuit 110 in the same row partition 120 is connected to the corresponding anode reset node A: the anode reset terminal Anode in each pixel driving circuit 110 in the same row partition 120 may be electrically connected to the anode reset node A respectively, or the anode reset node A may be electrically connected only to the anode reset terminal Anode in the first column of the pixel driving circuit 110 in the corresponding row partition 120, while the anode reset terminals Anode in other columns are electrically connected to the anode reset terminal Anode in the first column; Figure 2The specific position of the anode reset terminal Anode is not shown in the figure, and the position of the anode reset terminal Anode will be marked in the specific circuit structure of the pixel driving circuit 110 later; therefore, no matter which connection method is used, as long as in the light-emitting stage of the light-emitting diode OLED, the anode reset terminal Anode in each pixel driving circuit 110 in the same row partition 120 can receive the anode reset voltage on the anode reset node A.

[0049] Optionally, the driver chip 200 includes K reset voltage output terminals B, and the reset voltage output terminals B are connected to the anode reset nodes A one-to-one; the driver chip 200 is used to obtain the target anode reset voltage corresponding to each row partition 120, and output the target anode reset voltage to the anode reset node A of the corresponding row partition through the reset voltage output terminal B, so that the target anode reset voltage compensates for the anode voltage of the light-emitting diode in the light-emitting stage.

[0050] It should be noted that, in the present embodiment, the driver chip 200 includes K reset voltage output terminals B, and each reset voltage output terminal B is connected one-to-one with the anode reset node A of the row partition 120 in the display panel 100, so that each reset voltage output terminal B outputs a corresponding anode reset voltage to the corresponding anode reset node A, that is, the target anode reset voltage received on the anode reset node A in each row partition 120 may be different.

[0051] It should be further explained that: in addition to providing the anode reset voltage for the display panel 100, the driver chip 200 also provides other signals such as data voltage, driving voltage, scanning signal, etc. to drive the pixel driving circuit 110; the pixel driving circuits arranged in the array in the display panel 100 are sequentially regarded as the pixel driving circuits in the first row to the pixel driving circuits in the Mth row from top to bottom, and the driver chip 200 is usually arranged close to the pixel driving circuits in the Mth row, so the pixel driving circuits in the first row are regarded as the far end, and the pixel driving circuits in the Mth row are regarded as the near end. Due to the line resistance, when the pixel driving circuits gradually move away from the driver chip 200, the driving voltage VDD gradually decreases. Taking the driving voltage in the row partition 120 as a comparison unit as an example: VDD1<VDD2<…<VDDK, which will cause the driving voltage VDD between the row partitions 120 to be unstable, affecting the overall display brightness of the display panel 100. However, in this embodiment, by receiving different target anode reset voltages on the anode reset node A in each row partition 120, different anode reset voltages are used to compensate for the voltage drop problem of the driving voltage, thereby improving the problem of uneven display brightness.

[0052] In summary, the technical solution provided by this application has the following beneficial effects:

[0053] 1. The present application sets an anode reset terminal Anode for each pixel driving circuit 110 to receive an anode reset voltage, so that the anode reset voltage can not only reset the anode voltage of the light-emitting diode OLED to prevent the anode voltage of the previous frame from affecting the charging voltage of the current frame, but also compensate the anode voltage in the light-emitting stage to solve the problem of display delay in low grayscale or high refresh conditions and improve the uniformity of display brightness.

[0054] 2. The present application divides the pixel driving circuit 110 arranged in an array in the display panel 100 into a plurality of independent row partitions 120, and the anode reset voltage of each row partition 120 is differentially controlled by the driving chip 200, thereby compensating for the voltage drop problem of the driving voltage between different row partitions 120, and further improving the uniformity of the display brightness.

[0055] Figure 3 FIG. 1 is a schematic diagram of a pixel driving circuit 110 provided in an embodiment of the present application; Figure 3 As shown, the pixel driving circuit 110 includes: a driving transistor T1, an anode reset transistor T2, a data writing transistor T3, a first control transistor T4, a second control transistor T5 and a storage capacitor Cst.

[0056] The control end of the driving transistor T1 and the first end of the storage capacitor Cst are respectively connected to the first node Q, the first end of the driving transistor T1 is connected to the first end of the first control transistor T4, and the second end of the driving transistor T1 is connected to the first end of the second control transistor T5; the second end of the first control transistor T4 and the second end of the storage capacitor Cst are respectively electrically connected to the power line ELVDD, the second end of the second control transistor T5 and the anode of the light emitting diode OLED are respectively connected to the second node P, and the control end of the first control transistor T4 and the control end of the second control transistor T5 are respectively electrically connected to the light emitting control line EM; the control end of the data writing transistor T3 is electrically connected to the first scanning line S1, the first end of the data writing transistor T3 is electrically connected to the data line Data, and the second end of the data writing transistor T3 is connected to the first end of the driving transistor T1; the control end of the anode reset transistor T2 is electrically connected to the first scanning line S1, the first end of the anode reset transistor T2 is connected to the anode reset node A, the second end of the anode reset transistor T2 is connected to the second node P, and the cathode of the light emitting diode OLED is grounded.

[0057] Optionally, the pixel driving circuit 110 also includes: an initialization transistor T6 and a compensation transistor T7; the control end of the initialization transistor T6 is electrically connected to the second scan line S2, the first end of the initialization transistor T6 is electrically connected to the initialization signal line Vint, and the second end of the initialization transistor T6 is connected to the first node Q; the control end of the compensation transistor T7 is electrically connected to the third scan line S3, the first end of the compensation transistor T7 is connected to the first node Q, and the second end of the compensation transistor T7 is connected to the second end of the driving transistor T1.

[0058] Optionally, the data writing transistor T3, the anode reset transistor T2, the first control transistor T4 and the second control transistor T5 are P-type MOS transistors, and the initialization transistor T6, the compensation transistor T7 and the driving transistor T1 are N-type MOS transistors.

[0059] Combination Figure 3 and Figure 4 , the working principle of the pixel driving circuit 110 provided in this embodiment is:

[0060] In the initialization stage, the initialization transistor T6 is controlled to be turned on, and the data writing transistor T3, the first control transistor T4, the second control transistor T5, the compensation transistor T7 and the anode reset transistor T2 are controlled to be turned off, so that the initial voltage output on the initialization signal line Vint initializes the first node Q; wherein the on and off states of the transistors in the pixel driving circuit 110 are as shown in FIG. Figure 5 At the same time, the K reset voltage output terminals B of the control driving chip 200 output the corresponding target anode reset voltage to the anode reset node A of the corresponding row partition 120.

[0061] It should be noted that in this stage, the first node Q is mainly reset. At this time, the first scan line S1 and the second scan line S2 are both at a high potential, the third scan line S3 is at a low potential, and the light-emitting control line EM is at a high potential, so that only the initialization transistor T6 in the pixel driving circuit 110 is in the on state, and the initialization voltage output on the initialization signal line Vint resets the first node Q, that is, the voltage on the first node Q is equal to the initialization voltage. At the same time, the initialization voltage charges the storage capacitor Cst to ensure that the driving transistor T1 is turned on in the subsequent stage.

[0062] In the data sampling stage, the data writing transistor T3, the compensation transistor T7 and the anode reset transistor T2 are controlled to be turned on at the same time, the data voltage output on the data line Data is written into the first node Q, and the data voltage charges the storage capacitor Cst, and the target anode reset voltage on the anode reset node A is written into the second node P; wherein the on and off states of the transistors in the pixel driving circuit 110 are as shown in FIG. Figure 6 shown.

[0063] It should be noted that, in this stage, the third scan line S3 is at a high potential, the first scan line S1 and the second scan line S2 are at a low potential, and the light emitting control line EM is at a high potential, so that only the data writing transistor T3, the driving transistor T1, the compensation transistor T7 and the anode reset transistor T2 in the circuit are in a conducting state, the first node Q stores the data voltage, and the potential of the second node P is refreshed by the anode reset voltage; at this time, the gate voltage V g =V th +V data , where V th represents the threshold voltage of the driving transistor T1, V data Represents data voltage; anode voltage U of light-emitting diode OLED Cel =VI Anode ; Among them, VI Anode Indicates the anode reset voltage.

[0064] In the light emitting stage, the first control transistor T4 and the second control transistor T5 are controlled to be turned on, and the on and off states of the transistors in the pixel driving circuit 110 are as follows: Figure 7 As shown; in this stage, the first scan line S1 is at a high potential, the second scan line S2 and the third scan line S3 are at a low potential, and the light emitting control line EM is at a low potential. At this time, only the first control transistor T4, the driving transistor T1 and the second control transistor T5 are in a conducting state, and the light emitting layer is charged through the driving transistor T1, so that the potential of the second node P gradually rises, that is, the calculation formula of the anode voltage of the light emitting diode OLED is:

[0065] U Cel =VI Anode +I×t / C el (3)

[0066] By comparing formula (2) and formula (3), we can know that the anode reset voltage VI Anode The anode voltage of the light emitting diode OLED is compensated, and the voltage across the equivalent capacitor of the light emitting layer is adjusted, so that the compensated anode voltage drives the light emitting diode OLED to emit light more quickly, thereby achieving the purpose of adjusting the light emission delay.

[0067] This embodiment also realizes compensation of the driving current through the compensation transistor T7. The calculation formula of the driving current is shown in Formula 1, and V gs =V g -VDD, V g =V th +V data Therefore, after transforming formula (1), the calculation formula of the driving current in this embodiment is obtained:

[0068]

[0069] It can be seen from formula (4) that the driving current in this embodiment is independent of the threshold voltage of the driving transistor T1, thereby achieving compensation for the driving current, that is, compensation for the threshold voltage of the driving transistor T1.

[0070] In one embodiment, the connection relationship between the anode reset terminal Anode in each pixel driving circuit 110 in the same row partition 120 and the corresponding anode reset node A is as follows: Figure 8 As shown, the anode reset node A is only electrically connected to the anode reset terminal Anode in the first column of the pixel driving circuit 110 in the corresponding row partition 120, while the anode reset terminals Anode in other columns are electrically connected to the anode reset terminal Anode in the first column. Figure 8 The row partition 120 in FIG. 1 is taken as an example of one row of pixels.

[0071] In one embodiment, the present application provides a display driving method, which is applied to the display device 10 of the above embodiment. Fig. 9 As shown, the display driving method specifically includes the following steps:

[0072] Step S100 : in the test phase, obtaining the actual brightness image of the display panel 100 when displaying the preset brightness image.

[0073] It should be noted that the preset brightness picture is a pure color picture with the same grayscale displayed for each pixel. The test phase can be a test before the display device 10 leaves the factory, or it can be a test after the display device 10 has been used for a period of time. The data voltage of the preset brightness picture is sent to the driver chip 200 through the timing controller, so that the driver chip 200 display device 10 drives the display panel 100 to display the preset brightness picture, and then the actual brightness picture of the display panel 100 at this time is obtained by taking pictures or other technologies. In actual display, due to line resistance, low grayscale or high refresh, the actual brightness picture of the display panel 100 is different from the display brightness of the preset brightness picture.

[0074] Step S200 , obtaining a target anode reset voltage corresponding to each row partition 120 according to the brightness difference between the preset brightness picture and the actual brightness picture, and writing all the target anode reset voltages into the driver chip 200 .

[0075] In this embodiment, the brightness difference between the preset brightness picture and the actual brightness picture includes the brightness difference of the overall brightness between the actual brightness picture and the preset brightness picture, and also includes the brightness difference between the brightness of a local area in the actual brightness picture and the preset brightness picture.

[0076] like Fig.10As shown, according to the brightness difference between the preset brightness picture and the actual brightness picture, obtaining the target anode reset voltage corresponding to each row partition 120 and writing all the target anode reset voltages into the driver chip 200 specifically includes the following steps:

[0077] Step S210 : setting the same initial anode reset voltage for each row subarea 120 .

[0078] Step S220, determining whether there is a brightness difference in the actual brightness picture, and executing step S230 when there is a brightness difference, and executing step S260 when there is no brightness difference.

[0079] It should be noted that when the grayscale values ​​displayed by all pixels in the actual brightness picture are the same, it means that there is no brightness difference in the actual brightness picture; when the grayscale values ​​displayed by some pixels in the actual brightness picture are different from the grayscale values ​​of the preset brightness picture, it means that there is a brightness difference in the actual brightness picture; the brightness difference makes the picture display uneven.

[0080] In one embodiment, determining whether there is a brightness difference in the actual brightness picture specifically includes the following steps:

[0081] (1) Grayscale the actual brightness image to obtain a grayscale image.

[0082] It should be noted that in order to speed up the processing, the color image needs to be converted into a grayscale image, because the algorithm verified on the grayscale image can be easily transplanted to the color image. Each pixel of the 24-bit color image is represented by three sub-pixels, and each sub-pixel corresponds to the brightness of the R, G, and B components (red, green, and blue). When the R, G, and B component values ​​are the same, it is presented as a grayscale image. At this time, any one of the R, G, and B component values ​​can represent the grayscale value of the pixel. The following conversion formula is used: Gray(i, j) = 0.299*R(i, j) + 0.587*G(i, j) + 0.114*B(i, j); where R(i, j), G(i, j), and B(i, j) are the brightness values ​​of the three channels of R, G, and B, respectively.

[0083] (2) Divide the grayscale image into multiple detection areas and obtain the grayscale histogram corresponding to each detection area;

[0084] It should be noted that the grayscale image is divided into several detection areas according to preset rules, and the size of each detection area can be the same or different. The grayscale range of the image is 0-255, which is divided into 50 intervals. The grayscale histogram of the first 10 intervals (grayscale values ​​0-51) is displayed in red, the grayscale histogram of the last 10 intervals (grayscale values ​​204-255) is displayed in blue, and the grayscale histogram of the middle 30 intervals (grayscale values ​​52-203) is displayed in green.

[0085] (3) According to the grayscale histogram of each detection area, calculate the grayscale distribution factor corresponding to each detection area.

[0086] It should be noted that the sum of the grayscale histograms of the first 10 intervals, sum2 of the grayscale histograms of the last 10 intervals, and sum3 of the grayscale histograms of the middle 30 intervals are accumulated respectively. Different weights are assigned to these three intervals, the weights of the first 10 intervals and the last 10 intervals are both 0.2, and the weight of the middle 30 intervals is 0.6. Then the grayscale distribution factor a=0.2*sum1+0.6*sum2+0.6*sum3 is calculated.

[0087] (4) Each grayscale distribution factor is compared with a preset threshold value, and whether there is a brightness difference in the actual brightness picture is determined based on the comparison result.

[0088] It should be noted that the calculated grayscale distribution factor a is compared with a given threshold value θ=0.44. If a≥θ, it is determined to be a normal brightness display area; if a<θ, it is determined to be an abnormal brightness display area.

[0089] Step S230 , obtaining a normal target voltage of a normal brightness display area, an abnormal target voltage of an abnormal brightness display area, and at least one target row partition 120 corresponding to the abnormal brightness display area in the actual brightness picture.

[0090] It should be noted that the actual brightness image includes a normal brightness display area that displays the same grayscale value as the preset brightness image, and also includes an abnormal brightness display area that displays a grayscale value different from the preset brightness image; however, the anode voltage of the light-emitting diode OLED in the normal brightness display area when it emits light is the normal target voltage, and the anode voltage of the light-emitting diode OLED in the abnormal brightness display area when it emits light is the abnormal target voltage.

[0091] In addition, the row partition 120 corresponding to the abnormal brightness display area is used as the target row partition 120, and the target row partition 120 may be one row or multiple rows.

[0092] Optionally, obtaining a normal target voltage of a normal brightness display area in an actual brightness picture includes: obtaining a driving current corresponding to the normal brightness display area according to a preset current-brightness relationship table; and calculating a normal target voltage of the normal brightness display area according to the driving current, charging time and initial anode reset voltage.

[0093] It should be noted that the preset current-brightness relationship table is a table of the correspondence between display brightness and driving current established in advance. For example, when the display brightness is 127 grayscale, the corresponding driving current is 80mA; therefore, by querying the preset current-brightness relationship table with known brightness, the driving current corresponding to the normal brightness display area can be obtained; then according to the formula U Cel1 =VI Anode1 +I1×t / C el Calculate the normal target voltage U Cel1 , where VI Anode1 represents the initial anode reset voltage, and I1 represents the driving current corresponding to the normal brightness display area.

[0094] Optionally, obtaining the abnormal target voltage corresponding to the abnormal brightness display area in the actual brightness screen includes: obtaining the driving current corresponding to the abnormal brightness display area according to a preset current-brightness relationship table; and calculating the abnormal target voltage of the abnormal brightness display area according to the driving current, charging time and initial anode reset voltage. Similarly, this embodiment uses the same method as obtaining the normal target voltage to calculate the abnormal target voltage U Cel2 .

[0095] Step S240: Obtain a reset compensation value according to the difference between the normal target voltage and the abnormal target voltage.

[0096] In this embodiment, the reset compensation value U offset =U Cel1 -U Cel2 .

[0097] Step S250 , adding the reset compensation value to the initial anode reset voltage to obtain a target anode reset voltage corresponding to at least one target row partition 120 ; and using the initial anode reset voltage as the target anode reset voltage for other row partitions 120 except the target row partition 120 .

[0098] Step S260 : taking the initial anode reset voltage as the target anode reset voltage corresponding to each row partition 120 .

[0099] According to steps S220, S250 and S260, when there is no brightness difference in the actual brightness picture, the initial anode reset voltage is directly used as the target anode reset voltage corresponding to each row partition 120; when there is a brightness difference in the actual brightness picture, the initial anode reset voltage is added with the reset compensation value as the target anode reset voltage of the row partition 120 corresponding to the abnormal display area, and the initial anode reset voltage is used as the target anode reset voltage of the row partition 120 corresponding to the normal display area.

[0100] In summary, the target anode reset voltage corresponding to each row partition 120 can be obtained through the above steps S210-260, and all the target anode reset voltages can be written into the driver chip 200 through the timing controller, so that each reset voltage output of the driver chip 200 can output the corresponding target anode reset voltage.

[0101] Step S300, in the display stage, the K reset voltage output terminals B of the control driving chip 200 output the corresponding target anode reset voltage to the anode reset node A of the corresponding row partition 120, so that the target anode reset voltage compensates the anode voltage of the light emitting diode OLED in the light emitting stage.

[0102] Optionally, when the pixel driving circuit 110 includes a driving transistor T1, an anode reset transistor T2, a data writing transistor T3, a first control transistor T4, a second control transistor T5, an initialization transistor T6, a compensation transistor T7 and a storage capacitor Cst, in the display stage, the K reset voltage output terminals B of the control driving chip 200 are output to the corresponding target anode reset voltage to the anode reset node A of the corresponding row partition 120, so that the target anode reset voltage compensates the anode voltage of the light emitting diode OLED in the light emitting stage, including: in the initialization stage, the initialization transistor T6 is controlled to be turned on, and the data writing transistor T3, the first control transistor T4, the second control transistor T5, the compensation transistor T7 and the anode reset transistor T2 are controlled to be turned off, so that the initialization signal line Vin t to initialize the first node Q; at the same time, the K reset voltage output terminals B of the driving chip 200 are controlled to output the corresponding target anode reset voltage to the anode reset node A of the corresponding row partition 120; in the data sampling stage, the data writing transistor T3, the compensation transistor T7 and the anode reset transistor T2 are controlled to be turned on at the same time, the data voltage output on the data line Data is written into the first node Q, and the data voltage charges the storage capacitor Cst, and the target anode reset voltage on the anode reset node A is written into the second node P; in the light emitting stage, the first control transistor T4 and the second control transistor T5 are controlled to be turned on, the target anode reset voltage compensates the anode voltage of the light emitting diode OLED, and the compensated anode voltage drives the light emitting diode OLED to emit light.

[0103] It should be noted that the driving method in step S300 is the same as the working principle of the above-mentioned pixel driving circuit 110 , and will not be described in detail here.

[0104] like Fig.11 As shown, Fig.11U1 in the figure represents the initial anode reset voltage, U2 represents the target anode reset voltage after the initial anode reset voltage + reset compensation value, U3 represents the abnormal anode voltage corresponding to the light-emitting stage after the voltage drop, U4 represents the target anode voltage corresponding to the light-emitting stage, t1 represents the charging time after compensation, and t2 represents the target charging time. By comparison, it can be seen that after compensating the anode reset voltage, the time t1 to reach the target anode voltage is earlier than the time t2 when the normal curve reaches the target anode voltage, or within a sufficient and equal time, the compensated curve and the normal curve can finally reach the same level. Thus, the purpose of improving the light-emitting delay is achieved.

[0105] It should also be noted that since the cause of the unevenness of the display screen is not only related to the voltage drop, the solution only provides an exemplary compensation method. offset The setting value can be given by calculation or it can be gradually adjusted in the sample by human eyes or optical instruments.

[0106] In summary, the present application establishes a corresponding relationship between the row partition 120 in the display panel 100 and the anode reset voltage, and adjusts the anode reset voltage of the light-emitting diode OLED to keep the anode voltage unchanged during the light-emitting process, thereby achieving brightness correction.

[0107] In addition, the terms "first", "second", "third", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first", "second", "third" may explicitly or implicitly include one or more of the feature. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0108] In the description of this specification, the description with reference to the terms "some embodiments", "exemplarily", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0109] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application. Therefore, any changes or modifications made in accordance with the claims and description of the present application should fall within the scope of the patent of this application.

Claims

1. A display driving method, applied to a display device, characterized in that: The display device comprises a display panel and a driving chip, wherein the display panel comprises: K row partitions, each row partition includes an anode reset node and at least one row of pixel driving circuits; each of the pixel driving circuits includes at least a light emitting diode and an anode reset terminal; in the row partitions: the anode reset node is connected to the anode reset terminal of each pixel driving circuit; wherein K is a positive integer greater than 1; the driver chip includes K reset voltage output terminals, and the reset voltage output terminals are connected to the anode reset nodes in a one-to-one correspondence; the driver chip is used to obtain a target anode reset voltage corresponding to each row partition, and output the target anode reset voltage to the anode reset node of the corresponding row partition through the reset voltage output terminal, so that the target anode reset voltage compensates the anode voltage of the light emitting diode in the light emitting stage; The display driving method comprises: In the testing phase, the actual brightness of the display panel when displaying the preset brightness image is obtained; According to the brightness difference between the preset brightness picture and the actual brightness picture, a target anode reset voltage corresponding to each row partition is obtained, and all the target anode reset voltages are written into a driving chip; In the display stage, the K reset voltage output terminals of the driving chip are controlled to output the corresponding target anode reset voltage to the anode reset node of the corresponding row partition, so that the target anode reset voltage compensates the anode voltage of the light-emitting diode in the light-emitting stage.

2. The display driving method according to claim 1, characterized in that: The pixel driving circuit further includes: A driving transistor, an anode reset transistor, a data writing transistor, a first control transistor, a second control transistor and a storage capacitor; The control end of the driving transistor and the first end of the storage capacitor are respectively connected to the first node, the first end of the driving transistor is connected to the first end of the first control transistor, and the second end of the driving transistor is connected to the first end of the second control transistor; the second end of the first control transistor and the second end of the storage capacitor are respectively electrically connected to the power line, the second end of the second control transistor and the anode of the light emitting diode are respectively connected to the second node, and the control end of the first control transistor and the control end of the second control transistor are respectively electrically connected to the light emitting control line; The control end of the data writing transistor is electrically connected to the first scan line, the first end of the data writing transistor is electrically connected to the data line, and the second end of the data writing transistor is connected to the first end of the driving transistor; The control end of the anode reset transistor is electrically connected to the first scan line, the first end of the anode reset transistor is connected to the anode reset node, the second end of the anode reset transistor is connected to the second node, and the cathode of the light emitting diode is grounded.

3. The display driving method according to claim 2, characterized in that: The pixel driving circuit further includes: Initializing transistor and compensating transistor; The control end of the initialization transistor is electrically connected to the second scan line, the first end of the initialization transistor is electrically connected to the initialization signal line, and the second end of the initialization transistor is connected to the first node; The control end of the compensation transistor is electrically connected to the third scan line, the first end of the compensation transistor is connected to the first node, and the second end of the compensation transistor is connected to the second end of the driving transistor.

4. The display driving method according to claim 3, characterized in that: The data writing transistor, the anode reset transistor, the first control transistor and the second control transistor are P-type MOS transistors, and the initialization transistor, the compensation transistor and the driving transistor are N-type MOS transistors.

5. The display driving method according to claim 1, characterized in that: According to the brightness difference between the preset brightness picture and the actual brightness picture, a target anode reset voltage corresponding to each row partition is obtained, including: Setting the same initial anode reset voltage for each row partition; Determining whether there is a brightness difference in the actual brightness picture; When there is a brightness difference in the actual brightness picture, a normal target voltage of a normal brightness display area, an abnormal target voltage of an abnormal brightness display area, and at least one target row partition corresponding to the abnormal brightness display area in the actual brightness picture are obtained; the normal target voltage and the abnormal target voltage are anode voltages when the light emitting diode emits light; Obtaining a reset compensation value according to a difference between the normal target voltage and the abnormal target voltage; Adding the reset compensation value to the initial anode reset voltage to obtain a target anode reset voltage corresponding to the at least one target row partition; The initial anode reset voltage is used as a target anode reset voltage of other row sub-regions except the target row sub-region.

6. The display driving method according to claim 5, characterized in that: When there is no brightness difference in the actual brightness picture, the initial anode reset voltage is used as the target anode reset voltage corresponding to each row partition.

7. The display driving method according to claim 5, characterized in that: Obtaining a normal target voltage of a normal brightness display area in the actual brightness picture includes: According to a preset current-brightness relationship table, obtaining a driving current corresponding to the normal brightness display area; A normal target voltage of the normal brightness display area is calculated according to the driving current, the charging time and the initial anode reset voltage.

8. The display driving method according to claim 2, characterized in that: In the display stage, the K reset voltage output terminals of the driving chip are controlled to output the corresponding target anode reset voltage to the anode reset node of the corresponding row partition, so that the target anode reset voltage compensates the anode voltage of the light-emitting diode in the light-emitting stage, including: In the initialization stage, the initialization transistor is controlled to be turned on, and the data writing transistor, the first control transistor, the second control transistor, the compensation transistor and the anode reset transistor are controlled to be turned off, so that the initial voltage output on the initialization signal line initializes the first node; at the same time, the K reset voltage output terminals of the driving chip are controlled to output the corresponding target anode reset voltage to the anode reset node of the corresponding row partition; In the data sampling phase, the data writing transistor, the compensation transistor and the anode reset transistor are controlled to be turned on at the same time, the data voltage output on the data line is written into the first node, and the data voltage is used to charge the storage capacitor, and the target anode reset voltage on the anode reset node is written into the second node; In the light emitting stage, the first control transistor and the second control transistor are controlled to be turned on, the target anode reset voltage compensates the anode voltage of the light emitting diode, and the compensated anode voltage drives the light emitting diode to emit light.

9. The display driving method according to any one of claims 1 to 8, characterized in that: Determining whether there is a brightness difference in the actual brightness picture includes: Gray-scale the actual brightness image to obtain a grayscale image; Dividing the grayscale image into a plurality of detection areas, and obtaining a grayscale histogram corresponding to each of the detection areas; Calculating the grayscale distribution factor corresponding to each detection area according to the grayscale histogram of each detection area; Each grayscale distribution factor is compared with a preset threshold, and whether there is a brightness difference in the actual brightness picture is determined according to the comparison result.

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