CN113571014B - Pixel driving circuit and display panel - Google Patents

Pixel driving circuit and display panel Download PDF

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Publication number
CN113571014B
CN113571014B CN202110807272.2A CN202110807272A CN113571014B CN 113571014 B CN113571014 B CN 113571014B CN 202110807272 A CN202110807272 A CN 202110807272A CN 113571014 B CN113571014 B CN 113571014B
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transistor
signal
emitting device
electrically connected
node
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CN113571014A (en
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韩志斌
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Shenzhen China Star Optoelectronics Semiconductor Display Technology Co Ltd
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Shenzhen China Star Optoelectronics Semiconductor Display Technology Co Ltd
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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]
    • 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
    • G09G2320/02—Improving the quality of display appearance
    • G09G2320/0233—Improving the luminance or brightness uniformity across the screen

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Control Of Indicators Other Than Cathode Ray Tubes (AREA)
  • Control Of El Displays (AREA)

Abstract

The pixel driving circuit comprises a driving transistor, a first node and a second node, wherein the grid electrode of the driving transistor is electrically connected to the first node, and the source electrode of the driving transistor is connected to a first power supply signal; the anode of the light-emitting device is electrically connected to the drain electrode of the driving transistor, and the cathode of the light-emitting device is connected to a second power supply signal; the signal input module is accessed to the data signal and the first control signal and is electrically connected to the first node, and the signal input module is used for controlling the potential of the first node based on the data signal and the first control signal; and the voltage drop detection module is used for detecting the actual value of the cathode of the light-emitting device accessed by the second power signal under the control of the second control signal and adjusting the actual value of the data signal access signal input module based on the actual value of the cathode of the light-emitting device accessed by the second power signal. The display uniformity of the display panel can be improved.

Description

Pixel driving circuit and display panel
Technical Field
The application relates to the field of display, in particular to a pixel driving circuit and a display panel.
Background
In an Organic Light Emitting Diode (OLED) display panel, a Light Emitting mode is divided into two Light Emitting schemes of top emission and bottom emission. Among them, top emission has an advantage of a high aperture ratio, and display degradation due to the lifetime of a light emitting device can be alleviated.
However, top emission requires light emitted from the light emitting device to pass through a cathode of the light emitting device. Therefore, the thickness of the cathode of the light emitting device needs to be made thin to ensure light transmittance. This requirement causes the area resistance of the cathode of the light emitting device to become large. The large area resistance can make the voltage drops generated at different positions inconsistent, and affect the current of the light emitting device, thereby affecting the display uniformity of the OLED display panel.
Disclosure of Invention
The application provides a pixel driving circuit and a display panel, which are used for solving the technical problem of uneven display of the display panel caused by large surface resistance of a cathode of a light-emitting device.
In a first aspect, the present application provides a pixel driving circuit, comprising:
the grid electrode of the driving transistor is electrically connected to a first node, and the source electrode of the driving transistor is connected to a first power supply signal;
the anode of the light-emitting device is electrically connected to the drain electrode of the driving transistor, and the cathode of the light-emitting device is connected to a second power supply signal;
the signal input module is accessed to a data signal and a first control signal and is electrically connected to the first node, and the signal input module is used for controlling the potential of the first node based on the data signal and the first control signal;
the voltage drop detection module is connected to a second control signal and electrically connected to the cathode of the light-emitting device, and is used for detecting the actual value of the second power signal connected to the cathode of the light-emitting device under the control of the second control signal and adjusting the actual value of the data signal connected to the signal input module based on the actual value of the second power signal connected to the cathode of the light-emitting device.
In the pixel driving circuit provided by the present application, the signal input module includes a first transistor and a first capacitor;
the grid electrode of the first transistor is connected with the first control signal, the source electrode of the first transistor is connected with the data signal, and the drain electrode of the first transistor is electrically connected with the first node;
the first end of the first capacitor is electrically connected to the first node, and the second end of the first capacitor is electrically connected to the anode of the light emitting device.
In the pixel driving circuit provided by the present application, the voltage drop detecting module includes a second transistor, a second capacitor, and a detecting unit;
the grid electrode of the second transistor is connected to the second control signal, the drain electrode of the second transistor is electrically connected to the first end of the second capacitor and the detection unit, and the source electrode of the second transistor is electrically connected to the cathode of the light-emitting device; the second end of the second capacitor is electrically connected to the grounding end; the detection unit is used for detecting the actual value of the cathode of the light-emitting device accessed by the second power signal and adjusting the actual value of the signal input module accessed by the data signal based on the actual value of the cathode of the light-emitting device accessed by the second power signal.
In the pixel driving circuit provided by the present application, the voltage drop detecting module includes a second transistor, a second capacitor, and a detecting unit;
the grid electrode of the second transistor is connected to the second control signal, the drain electrode of the second transistor is electrically connected to the first end of the second capacitor and the detection unit, and the source electrode of the second transistor is electrically connected to the cathode of the light-emitting device; the second end of the second capacitor is electrically connected to the ground terminal; the detection unit is used for detecting an actual value of the cathode of the light-emitting device accessed by the second power signal, and acquiring a first compensation value corresponding to the second power signal and a second compensation value corresponding to the first power signal based on the actual value of the cathode of the light-emitting device accessed by the second power signal, so as to adjust the actual value of the signal input module accessed by the data signal.
In the pixel driving circuit provided by the present application, the driving circuit further includes a third transistor, a gate of the third transistor is connected to a third control signal, a source of the third transistor is electrically connected to the second node, and a drain of the third transistor is electrically connected to the first end of the second capacitor and the detecting unit;
the detecting unit is further configured to detect a potential of the second node under the control of the third control signal, and compensate the threshold voltage of the driving transistor based on the potential of the second node.
In the pixel driving circuit provided by the present application, the driving circuit further includes a third transistor, a gate of the third transistor is connected to a third control signal, a source of the third transistor is electrically connected to the second node, and a drain of the third transistor is electrically connected to the first end of the second capacitor and the first detecting unit;
the first detection unit is further configured to detect a potential of the second node under the control of the third control signal, and compensate the threshold voltage of the driving transistor based on the potential of the second node.
In the pixel driving circuit provided by the present application, the driving circuit further includes a third transistor, a gate of the third transistor is connected to a third control signal, a source of the third transistor is electrically connected to the second node, and a drain of the third transistor is electrically connected to the second detecting unit;
the second detection unit is configured to detect a potential of the second node under control of the third control signal, and compensate the threshold voltage of the driving transistor based on the potential of the second node.
In the pixel driving circuit provided by the present application, the pixel driving circuit calculates an actual value of the data signal accessing the signal input module according to the following formula: v data ＝V data_0 + A, wherein, V data Actual value, V, of the signal input module for the data signal access data_0 And A is the voltage difference between the actual value of the cathode of the second power supply signal connected to the light-emitting device and the standard value of the second power supply signal.
In the pixel driving circuit provided by the present application, the pixel driving circuit calculates an actual value of the data signal accessing the signal input module according to the following formula: v data ＝V data_0 +V data_VDD +V data_VSS ，V data Accessing the actual value of the signal input module for the data signal, V data_0 Is an initial value of the data signal, V data_VDD Is said second compensation value, V data_VSS Is the first compensation value.
In the pixel driving circuit provided by the present application, the pixel driving circuit calculates an actual value of the data signal accessing the signal input module according to the following formula: v data ＝V data_0 + A × B% (1-B%), wherein V data Actual value, V, of the signal input module for the data signal access data_0 And B% is a coupling loss coefficient in the pixel driving circuit.
In the pixel driving circuit provided by the application, the light emitting device is an organic light emitting diode.
In a second aspect, the present application further provides a display panel including any one of the pixel driving circuits described above.
According to the pixel driving circuit and the display panel, the voltage drop detection module is arranged to detect the actual value of the cathode of the second power signal connected to the light-emitting device, so that the actual value of the data signal connected to the signal input module can be adjusted based on the actual situation; that is, the embodiment of the application detects the second power signal connected to each pixel by setting a voltage drop detection module, and can adjust the data signal according to the detected second power signal, so that the display panel can not display unevenly due to voltage drop, and the display uniformity of the display panel can be improved.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a schematic diagram of a first structure of a pixel driving circuit according to an embodiment of the present disclosure;
fig. 2 is a first circuit diagram of a pixel driving circuit according to an embodiment of the present disclosure;
fig. 3 is a first timing diagram of a pixel driving circuit according to an embodiment of the present disclosure;
fig. 4 is a schematic path diagram of a pixel driving circuit in a detection stage according to the driving timing shown in fig. 3 according to an embodiment of the present disclosure;
fig. 5 is a schematic path diagram of a light emitting stage of a pixel driving circuit according to an embodiment of the present disclosure at the driving timing shown in fig. 3;
fig. 6 is a schematic diagram of a second structure of a pixel driving circuit according to an embodiment of the present disclosure;
fig. 7 is a second circuit diagram of a pixel driving circuit according to an embodiment of the disclosure;
fig. 8 is an output characteristic curve of a driving transistor in a pixel driving circuit according to an embodiment of the present disclosure;
fig. 9 is a second timing diagram of a pixel driving circuit according to an embodiment of the present disclosure;
fig. 10 is a schematic path diagram of a pixel driving circuit in a detection phase according to the driving timing shown in fig. 9 according to an embodiment of the present disclosure;
fig. 11 is a schematic diagram of a path of a pixel driving circuit in a light emitting stage according to the driving sequence shown in fig. 9;
fig. 12 is a third circuit diagram of a pixel driving circuit according to an embodiment of the present disclosure;
fig. 13 is a schematic diagram of a third structure of a pixel driving circuit according to an embodiment of the present disclosure;
fig. 14 is a fourth circuit diagram of a pixel driving circuit according to an embodiment of the present disclosure;
fig. 15 is a third timing diagram of a pixel driving circuit according to an embodiment of the present disclosure;
fig. 16 is a schematic path diagram of a pixel driving circuit in a detection phase according to the driving timing shown in fig. 15;
FIG. 17 is a schematic diagram illustrating a path of a pixel driving circuit in a light emitting stage according to the driving sequence shown in FIG. 15;
fig. 18 is a fifth circuit diagram of a pixel driving circuit according to an embodiment of the present disclosure;
fig. 19 is a sixth circuit diagram of a pixel driving circuit according to an embodiment of the present application
Fig. 20 is a schematic structural diagram of a display panel according to an embodiment of the present application.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. It is to be understood that the described embodiments are merely a few embodiments of the present application and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
It should be noted that the transistors used in all the embodiments of the present application may be thin film transistors or field effect transistors or other devices with the same characteristics. Since the source and the drain of the transistor adopted by the application are symmetrical, the source and the drain can be interchanged. In the embodiments of the present application, to distinguish two electrodes of a transistor except for a gate, one of the two electrodes is referred to as a source and the other is referred to as a drain. The form of the figure provides that the middle end of the transistor is a grid, the signal input end is a source, and the output end is a drain.
Referring to fig. 1, fig. 1 is a schematic diagram of a first structure of a pixel driving circuit according to an embodiment of the present disclosure. As shown in fig. 1, the present embodiment provides a pixel driving circuit 10, which includes a driving transistor T1, a light emitting device D, a signal input module 101, and a voltage drop detection module 102.
The gate of the driving transistor T1 is electrically connected to the first node b. The source of the driving transistor T1 is connected to the first power signal VDD. The anode of the light emitting device D is electrically connected to the drain of the driving transistor T1. The cathode of the light emitting device D is electrically connected to a second power signal VSS. The signal input module 101 is connected to the Data signal Data and the first control signal S1, and is electrically connected to the first node b. The signal input module 101 is configured to control a potential of the first node b based on the Data signal Data and the first control signal S1. The voltage drop detecting module 102 is connected to the second control signal S2 and electrically connected to the cathode of the light emitting device D.
The voltage drop detecting module 102 is configured to detect an actual value of the cathode of the light emitting device D accessed by the second power signal VSS under the control of the second control signal S2, and adjust an actual value of the Data signal Data accessed to the signal input module 101 based on the actual value of the cathode of the light emitting device D accessed by the second power signal VSS.
In the embodiment of the application, the voltage drop detecting module 102 detects the actual value of the cathode of the light emitting device D accessed by the second power signal VSS, so that the actual value of the Data signal Data access signal input module 101 can be adjusted based on the actual value of the cathode of the light emitting device D accessed by the second power signal VSS, thereby improving the display uniformity of the display panel.
In the embodiment of the present application, the driving transistor T1 is a small transistor that can pass enough current and has low on-resistance. The light emitting device D may be a light emitting diode device. For example, the light emitting device D may be an organic light emitting diode. The pixel driving circuit 10 provided in the embodiment of the present application adopts a current driving method. That is, the present embodiment provides a pixel driving circuit 10 in which the luminance of the light emitting device D is proportional to the magnitude of the current flowing through the light emitting device D.
In the embodiment of the present application, the first power signal VDD and the second power signal VSS are both used for outputting a predetermined voltage value. In addition, the potential of the first power supply signal VDD is larger than the potential of the second power supply signal VSS.
In the display panel, the pixels are arranged in a matrix including a plurality of rows and a plurality of columns, and each pixel receives the second power signal VSS to the cathode of the light emitting device D. However, the area resistance of the cathode of the light emitting device is large. The voltage drops generated at different positions are inconsistent due to the large area resistance, so that the second power signal VSS connected to each pixel changes along with the voltage drops. Therefore, in the embodiment of the present application, the voltage drop detecting module 102 is arranged to detect the second power signal VSS connected to each pixel, so that the Data signal Data can be adjusted according to the detected second power signal VSS, and thus the display panel does not have uneven display due to voltage drop.
Specifically, referring to fig. 2, fig. 2 is a first circuit diagram of a pixel driving circuit according to an embodiment of the present disclosure. It should be noted that the circuit diagram of the pixel driving circuit shown in fig. 2 is only one circuit implementation in the structural diagram of the pixel driving circuit shown in fig. 1. That is, the signal input module 101 and the voltage drop detection module 102 in fig. 1 can be implemented by various circuits.
As shown in fig. 2, the signal input module 101 includes a first transistor T2 and a first capacitor C1. The gate of the first transistor T2 is connected to the first control signal S1. The source of the first transistor T2 is connected to the data signal Dat. The drain of the first transistor T2 is electrically connected to the first node b. The first end of the first capacitor C1 is electrically connected to the first node b. The second end of the first capacitor C1 is electrically connected to the anode of the light emitting device D.
As shown in fig. 2, the voltage drop detecting module 102 includes a second transistor T3, a second capacitor C2 and a detecting unit 103. The gate of the second transistor T3 is connected to the second control signal S2. The drain of the second transistor T3 is electrically connected to the first end of the second capacitor C2 and the detecting unit 103. The source of the second transistor T3 is electrically connected to the cathode of the light emitting device D. The second end of the second capacitor C2 is electrically connected to the ground terminal N. The detecting unit 103 is configured to detect an actual value of the cathode of the light emitting device D accessed by the second power signal VSS, and adjust an actual value of the Data signal Data access signal input module 101 based on the actual value of the cathode of the light emitting device D accessed by the second power signal VSS. It should be noted that, in the embodiment of the present application, a specific circuit structure of the detection unit 103 is not provided, but based on a specific function of the detection unit 103, a person skilled in the art may set the specific circuit structure, which is not described herein again.
In the embodiment of the present application, the working process of the detecting unit 103 is as follows: the detecting unit 103 may detect an actual value of the cathode of the second power signal VSS connected to the light emitting device D, calculate a voltage difference between the actual value of the cathode of the second power signal VSS connected to the light emitting device D and a standard value of the second power signal VSS, and adjust an actual value of the Data signal Data connected to the signal input module 101 based on the voltage difference between the actual value of the cathode of the second power signal VSS connected to the light emitting device D and the standard value of the second power signal VSS. The standard value of the second power signal VSS refers to a preset value of the second power signal VSS connected to each pixel, and the preset value does not consider the change of the second power signal VSS connected to each pixel caused by voltage drop. That is, the standard values of the second power signals VSS connected to the respective pixels are the same.
In the embodiment of the present application, the first transistor T2, the second transistor T3, and the driving transistor T1 are all N-type transistors. Of course, in other embodiments, the first transistor T2, the second transistor T3, and the driving transistor T1 may all be P-type transistors. The P-type transistor is switched on when the grid is at a low level and is switched off when the grid is at a high level; the N-type transistor is turned on when the gate is at a high level and turned off when the gate is at a low level.
In one embodiment, the first transistor T2, the second transistor T3, and the driving transistor T1 are each a low temperature polysilicon thin film transistor, an oxide semiconductor thin film transistor, or an amorphous silicon thin film transistor. The transistors in the light emitting diode driving circuit provided by the embodiment of the application are the same type of transistors, so that the influence of difference among different types of transistors on the light emitting diode driving circuit is avoided.
In the embodiment of the present application, the pixel driving circuit 10 calculates the actual value of the Data signal Data access signal input module 101 according to the following formula: v data ＝V data_0 + A, wherein, V data The actual value, V, of the signal input module 101 is used for the Data signal Data data_0 As an initial value of the Data signal Data, a is a voltage difference between an actual value of the second power signal VSS connected to the cathode of the light emitting device D and a standard value of the second power signal VSS.
Referring to fig. 3, fig. 3 is a first timing diagram of a pixel driving circuit according to an embodiment of the present disclosure. As shown in fig. 3, the combination of the first control signal S1 and the second control signal S2 corresponds to the detection phase and the light-emitting phase. In the detecting stage, the first control signal S1 is at a low voltage level, and the second control signal S2 is at a high voltage level. In the light emitting period, the first control signal S1 is at a high level, and the second control signal S2 is at a low level.
Specifically, referring to fig. 3 and 4, fig. 4 is a schematic path diagram of a pixel driving circuit provided in an embodiment of the present application in a detection stage under the driving timing shown in fig. 3. Referring to fig. 3 and 4, in the detecting stage, the first control signal S1 is at a low voltage level, and the second control signal S2 is at a high voltage level. At this time, the first transistor T2 is turned off under the control of the first control signal S1. At this time, the second transistor T3 is turned on by the first capacitor C1. The second transistor T3 is turned on under the control of the second control signal S2, the detecting unit 103 detects an actual value of the second power signal VSS connected to the cathode of the light emitting device D through the second transistor T3, and the potential M of the actual value of the second power signal VSS connected to the cathode of the light emitting device D gradually rises to a stable potential under the action of the second capacitor C2, and at this time, an actual value of the second power signal VSS connected to the cathode of the light emitting device D is obtained through detection.
Further, the detecting unit 103 adjusts an actual value of the Data signal Data accessing signal input module 101 based on an actual value of the cathode of the second power signal VSS accessing the light emitting device D.
Referring to fig. 3 and 5, fig. 5 is a schematic path diagram of a pixel driving circuit in a light emitting stage at the driving timing shown in fig. 3 according to an embodiment of the present disclosure. As shown in fig. 3 and 5, in the light emitting stage, the first control signal S1 is at a high level, and the second control signal S2 is at a low level. At this time, the first transistor T2 is turned on under the control of the first control signal S1, and the actual value of the Data signal Data accessing the signal input module 101 is output to the first node b through the first transistor T2, so that the driving transistor T1 is turned on, and the light emitting device D emits light. The second transistor T3 is turned off under the control of the second control signal S2.
In the embodiment of the application, the voltage drop detection module 102 is arranged to detect the actual value of the cathode of the second power signal VSS connected to the light emitting device D, and the actual value of the Data signal Data connected to the signal input module 101 can be adjusted based on the actual value of the cathode of the second power signal VSS connected to the light emitting device D, so that the display uniformity of the display panel can be improved.
Referring to fig. 6, fig. 6 is a schematic diagram of a second structure of a pixel driving circuit according to an embodiment of the present disclosure. As shown in fig. 6, the present embodiment provides a pixel driving circuit 20, which includes a driving transistor T1, a light emitting device D, a signal input module 101, and a voltage drop detection module 102.
The gate of the driving transistor T1 is electrically connected to the first node M. The source of the driving transistor T1 is connected to the first power signal VDD. The drain of the driving transistor T1 is electrically connected to the second node N. The anode of the light emitting device D is electrically connected to the second node N. The cathode of the light emitting device D is connected to a second power signal VSS. The signal input module 101 receives a Data signal Data and a first control signal S1, and is electrically connected to a first node M and a second node N. The signal input module 101 is configured to control a potential of the first node M and a potential of the second node N based on the first control signal S1 and the Data signal Data. The voltage drop detecting module 102 is connected to the second control signal S2 and electrically connected to the cathode of the light emitting device D.
The voltage drop detecting module 102 is configured to detect an actual value of the cathode of the light emitting device D accessed by the second power signal VSS under the control of the second control signal S2, and obtain a first compensation value corresponding to the second power signal VSS and a second compensation value corresponding to the first power signal VDD based on the actual value of the cathode of the light emitting device D accessed by the second power signal VSS, so as to adjust the actual value of the Data signal Data accessed to the signal input module 101.
In the embodiment of the present application, the driving transistor T1 is a small transistor that can pass enough current and has low on-resistance. The light emitting device D may be a light emitting diode device. For example, the light emitting device may be an organic light emitting diode.
In the display panel, the pixels are arranged in a matrix including a plurality of rows and a plurality of columns, and each pixel is connected to the first power signal VDD through a power line. However, the voltage drop on the power line causes the first power signal VDD switched in by each pixel to vary with the voltage drop on the power line. In order to reduce the influence of the variation of the driving transistor T1 on the light emitting device D, the driving transistor T1 is generally operated in a saturation region to drive the light emitting device D. However, in an actual manufacturing process, the saturation characteristic of the driving transistor T1 is not completely saturated, and especially in a case where a voltage drop exists in the power line, the current of the light emitting device may be changed due to the voltage drops at different points.
Based on this, in the embodiment of the present application, the voltage drop detecting module 102 is arranged to detect the second power signal VSS connected to each pixel, and obtain the second compensation value corresponding to the first power signal VDD based on the actual value of the cathode of the light emitting device D connected to the second power signal VSS, so that the Data signal Data can be adjusted according to the first power signal VDD, thereby improving the display uniformity of the display panel.
In the display panel, the pixels are arranged in a matrix including a plurality of rows and a plurality of columns, and each pixel receives the second power signal VSS to the cathode of the light emitting device D. However, the area resistance of the cathode of the light emitting device D is large. The voltage drops generated at different positions are inconsistent due to the large area resistance, so that the second power signal VSS connected to each pixel changes along with the voltage drops.
Based on this, in the embodiment of the application, the voltage drop detecting module 102 is arranged to detect the second power signal VSS connected to each pixel, and obtain the first compensation value corresponding to the second power signal VSS based on the actual value of the cathode of the light emitting device D connected to the second power signal VSS, so that the Data signal Data can be adjusted according to the second power signal VSS, and the display uniformity of the display panel is further improved.
That is, in the embodiment of the present application, the voltage drop detecting module 102 is arranged to adjust the Data signal Data according to the first power signal VDD and the second power signal VSS at the same time, so as to improve the display uniformity of the display panel.
Specifically, referring to fig. 7, fig. 7 is a second circuit diagram of a pixel driving circuit according to an embodiment of the present disclosure. It should be noted that the circuit diagram of the pixel driving circuit shown in fig. 7 is only one circuit implementation in the structural diagram of the pixel driving circuit shown in fig. 6. That is, the signal input module 101 and the voltage drop detection module 102 in fig. 6 can be implemented by various circuits.
As shown in fig. 7, the signal input module 101 includes a first transistor T2 and a first capacitor C1. The gate of the first transistor T2 is connected to the first control signal S1. The source of the first transistor T2 is connected to the Data signal Data. The drain of the first transistor T2 is electrically connected to the first node M. The first end of the first capacitor C1 is electrically connected to the first node M. The second end of the first capacitor C1 is electrically connected to the second node N.
As shown in fig. 7, the voltage drop detecting module 102 includes a second transistor T3, a second capacitor C2 and a detecting unit 103. The gate of the second transistor T3 is connected to the second control signal S2. The drain of the second transistor T3 is electrically connected to the first end of the second capacitor C2 and the detecting unit 103. The source of the second transistor T3 is electrically connected to the cathode of the light emitting device D. The second end of the second capacitor C2 is electrically connected to the ground. The detecting unit 103 is configured to detect an actual value of the cathode of the light emitting device D accessed by the second power signal VSS, and obtain a first compensation value corresponding to the second power signal VSS and a second compensation value corresponding to the first power signal VDD based on the actual value of the cathode of the light emitting device D accessed by the second power signal VSS, so as to adjust an actual value of the Data signal Data accessed to the signal input module 101.
It should be noted that, in the embodiment of the present application, a specific circuit structure of the detection unit 103 is not provided, but a person skilled in the art may set the specific circuit structure based on the specific function of the detection unit 103. For example, the detecting unit 103 may be a voltage detecting module in a chip of the display panel.
In the embodiment of the present application, the working process of the detecting unit 103 is as follows: the detecting unit 103 may first detect an actual value of the cathode of the second power signal VSS connected to the light emitting device D, then calculate a voltage difference between the actual value of the cathode of the second power signal VSS connected to the light emitting device D and a standard value of the second power signal VSS, and finally obtain a first compensation value corresponding to the second power signal VSS and a second compensation value corresponding to the first power signal VDD based on the voltage difference between the actual value of the cathode of the second power signal VSS connected to the light emitting device D and the standard value of the second power signal VSS, so as to adjust an actual value of the Data signal Data connected to the signal input module 101.
The standard value of the second power signal VSS refers to a preset value of the second power signal VSS connected to each pixel, and the preset value does not consider a change of the second power signal VSS connected to each pixel due to a voltage drop on a power line. That is, the standard values of the second power signals VSS connected to the respective pixels are the same.
In the embodiment of the present application, the driving transistor T1, the first transistor T2, and the second transistor T3 are all low temperature polysilicon thin film transistors, oxide semiconductor thin film transistors, or amorphous silicon thin film transistors. The transistors in the pixel driving circuit provided by the embodiment of the application are the same type of transistors, so that the influence of difference among different types of transistors on the pixel driving circuit is avoided.
Specifically, in the embodiment of the present application, the driving transistor T1, the first transistor T2, and the second transistor T3 are all N-type transistors. Of course, in other embodiments, the driving transistor T1, the first transistor T2 and the second transistor T3 may all be P-type transistors. The P-type transistor is switched on when the grid is at a low level and is switched off when the grid is at a high level; the N-type transistor is turned on when the gate is at a high level and turned off when the gate is at a low level.
In this embodiment, the pixel driving circuit may calculate an actual value of the data signal accessing signal input module according to the following formula: v data ＝V data_0 +V data_VDD +V data_VSS ，V data Accessing the actual value of the signal input module 101 for the Data signal Data; v data_0 The initial value of the Data signal Data can be preset; v data_VDD Is a second compensation value; v data_VSS Is the first compensation value.
Wherein the pixel driving circuit may calculate the first compensation value according to the following formula:
V data_VDD ＝V gs2 -V gs1 ，k*(V gs1 -V th ) 2 +a*A/c＝k*(V gs2 -V th ) 2 a is a second electrode
The source signal VSS is connected to the voltage difference between the actual value of the cathode of the light emitting device D and the standard value of the second power signal VSS; a is a preset constant; v gs1 A preset voltage difference is set between the grid electrode and the source electrode of the driving transistor T1; v gs2 Is the actual voltage difference between the gate and the source of the driving transistor T1; v th Is the threshold voltage of the drive transistor T1; c is the equivalent resistance ratio of the first power signal VDD and the second power signal VSS, and k is a constant.
Please refer to the drawingsFig. 8 is an output characteristic curve of a driving transistor in the pixel driving circuit according to the embodiment of the present application. As shown in fig. 8, the abscissa is the voltage V of the drain of the driving transistor T1 d Ordinate is the current I flowing through the drive transistor T1 d . Curves B1, B2 and B3 in fig. 8 represent different V, respectively gs The actual output characteristic curve of the lower driving transistor T1. The curves B11, B22 and B33 in FIG. 8 represent different V gs And the lower driving transistor T1 corresponds to a standard output characteristic curve. The curves B1 and B11 correspond to the same V gs The curves B2 and B22 correspond to the same V gs The curves B3 and B33 correspond to the same V gs 。V gs Is the voltage difference between the gate and the source of the driving transistor T1.
The embodiment of the application can be realized by the same V gs Next, an actual output characteristic of the next driving transistor T1 and a standard output characteristic of the next driving transistor T1 are obtained as a. Specifically, at the same V gs Next, the standard output characteristic curve of the driving transistor T1 in the saturation region can be calculated according to the following formula: i is d ＝k*(V gs -V th ) 2 (ii) a The actual output characteristic of the drive transistor T1 in the saturation region can be calculated according to the following formula: I.C. A d ＝k*(V gs -V th ) 2 +a*V d Wherein V is th Is the threshold voltage of the driving transistor T1. That is, in the embodiment of the present application, a and k may be calculated according to the above two formulas and are constants.
For example, a can be calculated by B1 and B11. Alternatively, a is calculated by B2 and B22. Alternatively, a is calculated by B3 and B33.
In some embodiments, a may be obtained by averaging different actual output characteristic curves and different standard output characteristic curves.
For example, a1 can be calculated by B1 and B11, a2 can be calculated by B2 and B22, a3 can be calculated by B3 and B33, and a is obtained by averaging a1, a2, and a 3.
In the actual manufacturing process of the display device, the output characteristic of the driving transistor T1 may be obtained through testing before shipping, a is obtained based on the actual output characteristic curve of the driving transistor T1 and the standard output characteristic curve of the driving transistor, and a is stored in the memory of the display device.
Wherein the pixel driving circuit may calculate the second compensation value according to the following formula:
V data_VSS = a × M%, a being a voltage difference between an actual value of the cathode of the second power supply signal VSS connected to the light emitting device D and a standard value of the second power supply signal VSS; m% is a coupling loss ratio of the driving transistor T1.
Also, the coupling loss ratio of the driving transistor T1 and the equivalent resistance ratio of the first power signal VDD and the second power signal VSS may be obtained through a test before the factory shipment, and the coupling loss ratio may be stored in the memory of the display device.
Referring to fig. 9, fig. 9 is a second timing diagram of a pixel driving circuit according to an embodiment of the present disclosure. As shown in fig. 9, the combination of the first control signal S1 and the second control signal S2 corresponds to the detection phase and the light-emitting phase. In the detecting stage, the first control signal S1 is at a low voltage level, and the second control signal S2 is at a high voltage level. In the light emitting period, the first control signal S1 is at a high level, and the second control signal S2 is at a low level.
Specifically, referring to fig. 9 and 10, fig. 10 is a schematic path diagram of a pixel driving circuit provided in the embodiment of the present application in a detection stage under the driving timing shown in fig. 9. Referring to fig. 9 and 10, in the detection phase, the first control signal S1 is at a low level, and the second control signal S2 is at a high level. At this time, the first transistor T2 is turned off under the control of the first control signal S1. The second transistor T3 is turned on under the control of the second control signal S2, the detecting unit 103 detects the actual value of the cathode of the light emitting device D connected to the second power signal VSS through the second transistor T3, and the potential F of the actual value of the cathode of the light emitting device D connected to the source of the driving transistor T1 connected to the second power signal VSS gradually rises to a stable potential under the action of the second capacitor C2. At this time, the actual value of the second power signal VSS connected to the cathode of the light emitting device D is obtained by detection.
Further, the detecting unit 103 obtains a first compensation value corresponding to the second power signal VSS and a second compensation value corresponding to the first power signal VDD based on an actual value of the second power signal VSS accessing the cathode of the light emitting device D, so as to adjust an actual value of the Data signal Data accessing the signal input module 101.
Referring to fig. 9 and 11, fig. 11 is a schematic path diagram of a pixel driving circuit according to an embodiment of the present disclosure in a light emitting stage at the driving timing shown in fig. 9. As shown in fig. 9 and 11, in the light emitting stage, the first control signal S1 is at a high level, and the second control signal S2 is at a low level. At this time, the first transistor T2 is turned on under the control of the first control signal S1, and the actual value of the Data signal Data accessing the signal input module 101 is output to the first node M through the first transistor T2, so that the driving transistor T1 is turned on, and the light emitting device D emits light. The second transistor T3 is turned off under the control of the second control signal S2.
Further, referring to fig. 12, fig. 12 is a third circuit diagram of a pixel driving circuit according to an embodiment of the present disclosure. The pixel drive circuit shown in fig. 12 differs from the pixel drive circuit shown in fig. 7 in that: the pixel driving circuit shown in fig. 12 further includes a third transistor T4. The gate of the third transistor T4 is switched on the third control signal S3. The source of the third transistor T4 is electrically connected to the second node N. The drain of the third transistor T4 is electrically connected to the first end of the second capacitor C2 and the detecting unit 103. The detecting unit 103 is further configured to detect a potential of the second node N under the control of the third control signal S3, and compensate the threshold voltage of the driving transistor T1 based on the potential of the second node N.
That is, the pixel driving circuit shown in fig. 12 can compensate for the threshold voltage of the driving transistor T1 in addition to the pixel driving circuit shown in fig. 7, thereby further improving the display uniformity of the display panel.
Referring to fig. 13, fig. 13 is a schematic diagram of a third structure of a pixel driving circuit according to an embodiment of the present disclosure. As shown in fig. 13, the present embodiment provides a pixel driving circuit 30, which includes a driving transistor T1, a light emitting device D, a signal input module 101, and a voltage drop detection module 102.
The gate of the driving transistor T1 is electrically connected to the first node b. The source of the driving transistor T1 is connected to the first power signal VDD. The anode of the light emitting device D is electrically connected to the drain of the driving transistor T1. The cathode of the light emitting device D is electrically connected to a second power signal VSS. The signal input module 101 is connected to the Data signal Data and the first control signal S1, and is electrically connected to the first node b. The signal input module 101 is used for controlling the potential of the first node b based on the Data signal Data and the first control signal S1. The voltage drop detecting module 102 is connected to the second control signal S2 and electrically connected to the cathode of the light emitting device D.
The voltage drop detecting module 102 is configured to detect an actual value of the second power signal VSS connected to the cathode of the light emitting device D under the control of the second control signal S2, and adjust an actual value of the Data signal Data connected to the signal input module 101 based on the actual value of the second power signal VSS connected to the cathode of the light emitting device D and the coupling loss coefficient in the pixel driving circuit 30.
In the embodiment of the application, the voltage drop detecting module 102 detects the actual value of the cathode of the second power signal VSS connected to the light emitting device D, so that the actual value of the Data signal Data connected to the signal input module 101 can be adjusted based on the actual value of the cathode of the second power signal VSS connected to the light emitting device D, thereby improving the display uniformity of the display panel.
In the embodiment of the present application, the driving transistor T1 is a small transistor that can pass enough current and has low on-resistance. The light emitting device D may be a light emitting diode device. For example, the light emitting device D may be an organic light emitting diode. The pixel driving circuit 30 provided in the embodiment of the present application adopts a current driving method. That is, the embodiment of the present application provides the pixel driving circuit 30 in which the luminance of the light emitting device D is proportional to the magnitude of the current flowing through the light emitting device D.
In the embodiment of the present application, the first power signal VDD and the second power signal VSS are both used for outputting a predetermined voltage value. In addition, the potential of the first power supply signal VDD is larger than the potential of the second power supply signal VSS.
In the display panel, the pixels are arranged in a matrix including a plurality of rows and a plurality of columns, and each pixel receives the second power signal VSS to the cathode of the light emitting device D. However, the area resistance of the cathode of the light emitting device is large. The voltage drops generated at different positions are inconsistent due to the large area resistance, so that the second power signal VSS connected to each pixel changes along with the voltage drops. Therefore, in the embodiment of the application, the voltage drop detection module 102 is arranged to detect the second power signal VSS connected to each pixel, so that the Data signal Data can be adjusted according to the detected second power signal VSS, and the display panel does not suffer from display unevenness due to voltage drop.
Specifically, referring to fig. 14, fig. 14 is a fourth circuit diagram of the pixel driving circuit according to the embodiment of the present disclosure. It should be noted that the circuit diagram of the pixel driving circuit shown in fig. 14 is only one circuit implementation in the structural diagram of the pixel driving circuit shown in fig. 13. That is, the signal input module 101 and the voltage drop detection module 102 in fig. 13 can be implemented by various circuits.
As shown in fig. 14, the signal input module 101 includes a first transistor T2 and a first capacitor C1. The gate of the first transistor T2 is connected to the first control signal S1. The source of the first transistor T2 is connected to the Data signal Data. The drain of the first transistor T2 is electrically connected to the first node b. The first end of the first capacitor C1 is electrically connected to the first node b. The second end of the first capacitor C1 is electrically connected to the anode of the light emitting device D.
As shown in fig. 14, the voltage drop detecting module 102 includes a second transistor T3, a second capacitor C2 and a first detecting unit 103. The gate of the second transistor T3 is connected to the second control signal S2. The drain of the second transistor T3 is electrically connected to the first end of the second capacitor C2 and the first detecting unit 103. The source of the second transistor T3 is electrically connected to the cathode of the light emitting device D. The second end of the second capacitor C2 is electrically connected to the ground terminal N. The first detecting unit 103 is configured to detect an actual value of the second power signal VSS connected to the cathode of the light emitting device D, and adjust an actual value of the Data signal Data connected to the signal input module 101 based on the actual value of the second power signal VSS connected to the cathode of the light emitting device D and a coupling loss coefficient in the pixel driving circuit 30.
It should be noted that, in the embodiment of the present application, a specific circuit structure of the first detecting unit 103 is not provided, but a person skilled in the art may set a specific circuit structure based on the specific function of the first detecting unit 103. For example, the first detecting unit 103 may be a voltage detecting module in a chip of the display panel.
In the embodiment of the present application, the working process of the first detecting unit 103 is as follows: the first detecting unit 103 may first detect an actual value of the cathode of the second power signal VSS connected to the light emitting device D, then calculate a voltage difference between the actual value of the cathode of the second power signal VSS connected to the light emitting device D and a standard value of the second power signal VSS, and finally adjust an actual value of the Data signal Data connected to the signal input module 101 based on the voltage difference between the actual value of the cathode of the second power signal VSS connected to the light emitting device D and the standard value of the second power signal VSS and a coupling loss coefficient in the pixel driving circuit 30. The standard value of the second power signal VSS refers to a preset value of the second power signal VSS connected to each pixel, and the preset value does not consider a change of the second power signal VSS connected to each pixel due to a voltage drop. That is, the standard values of the second power signals VSS connected to the respective pixels are the same.
In the embodiment of the present application, the first transistor T2, the second transistor T3, and the driving transistor T1 are all N-type transistors. Of course, in other embodiments, the first transistor T2, the second transistor T3, and the driving transistor T1 may all be P-type transistors. The P-type transistor is switched on when the grid is at a low level and is switched off when the grid is at a high level; the N-type transistor is turned on when the gate is at a high level and turned off when the gate is at a low level.
In one embodiment, the first transistor T2, the second transistor T3, and the driving transistor T1 are each a low temperature polysilicon thin film transistor, an oxide semiconductor thin film transistor, or an amorphous silicon thin film transistor. The transistors in the light emitting diode driving circuit provided by the embodiment of the application are the same type of transistors, so that the influence of difference among different types of transistors on the light emitting diode driving circuit is avoided.
In the embodiment of the present application, the pixel driving circuit 30 calculates the actual value of the Data signal Data access signal input module 101 according to the following formula: v data ＝V data_0 + A × B% (1-B%), wherein V data The actual value, V, of the signal input module 101 is used for the Data signal Data data_0 As an initial value of the Data signal Data, a is a voltage difference between an actual value of the second power signal VSS connected to the cathode of the light emitting device D and a standard value of the second power signal VSS, and B% is a coupling loss coefficient in the pixel driving circuit 30.
For example, the coupling coefficient in the pixel drive circuit 30 is defined as: vs raises nV, vg raises mV, and B% = (n-m)/n × 100%, where Vs is the voltage of the drain of the driving transistor T1, and Vg is the voltage of the gate of the driving transistor T1.
Referring to fig. 15, fig. 15 is a third timing diagram of a pixel driving circuit according to an embodiment of the present disclosure. As shown in fig. 15, the combination of the first control signal S1 and the second control signal S2 corresponds to the detection phase and the light-emitting phase. In the detecting stage, the first control signal S1 is at a low voltage level, and the second control signal S2 is at a high voltage level. In the light emitting period, the first control signal S1 is at a high level, and the second control signal S2 is at a low level.
Specifically, referring to fig. 15 and 16, fig. 16 is a schematic path diagram of a pixel driving circuit provided in the embodiment of the present application in a detection stage under the driving timing shown in fig. 15. Referring to fig. 15 and 16, in the detecting stage, the first control signal S1 is at a low voltage level, and the second control signal S2 is at a high voltage level. At this time, the first transistor T2 is turned off under the control of the first control signal S1. At this time, the second transistor T3 is turned on by the first capacitor C1. The second transistor T3 is turned on under the control of the second control signal S2, the first detecting unit 103 detects an actual value of the second power signal VSS connected to the cathode of the light emitting device D through the second transistor T3, and the potential M of the actual value of the second power signal VSS connected to the cathode of the light emitting device D gradually rises to a stable potential under the action of the second capacitor C2, and at this time, the actual value of the second power signal VSS connected to the cathode of the light emitting device D is obtained through detection.
Further, the first detecting unit 103 adjusts an actual value of the Data signal Data accessing signal input module 101 based on an actual value of the second power signal VSS accessing the cathode of the light emitting device D.
Referring to fig. 15 and 17, fig. 17 is a schematic path diagram of a pixel driving circuit in a light emitting stage at the driving timing shown in fig. 15 according to an embodiment of the present disclosure. As shown in fig. 15 and 17, in the light emitting stage, the first control signal S1 is at a high level, and the second control signal S2 is at a low level. At this time, the first transistor T2 is turned on under the control of the first control signal S1, and the actual value of the Data signal Data accessing the signal input module 101 is output to the first node b through the first transistor T2, so that the driving transistor T1 is turned on, and the light emitting device D emits light. The second transistor T3 is turned off under the control of the second control signal S2.
In the embodiment of the application, by setting the voltage drop detecting module 102 to detect the actual value of the cathode of the second power signal VSS connected to the light emitting device D, the actual value of the Data signal Data connected to the signal input module 101 can be adjusted based on the actual value of the cathode of the light emitting device D connected to the second power signal VSS and the coupling loss coefficient in the pixel driving circuit 30, so that the display uniformity of the display panel can be improved.
Further, referring to fig. 18, fig. 18 is a fifth circuit diagram of a pixel driving circuit according to an embodiment of the present disclosure. The pixel drive circuit 30 shown in fig. 18 differs from the pixel drive circuit 30 shown in fig. 14 in that: the pixel driving circuit 30 shown in fig. 18 further includes a third transistor T4. The gate of the third transistor T4 is switched on the third control signal S3. The source of the third transistor T4 is electrically connected to the second node N. The drain of the third transistor T4 is electrically connected to the first end of the second capacitor C2 and the first detecting unit 103. The first detecting unit 103 is further configured to detect a potential of the second node N under the control of the third control signal S3, and compensate the threshold voltage of the driving transistor T1 based on the potential of the second node N.
That is, the pixel driving circuit 30 shown in fig. 18 can compensate for the threshold voltage of the driving transistor T1 in addition to the pixel driving circuit 30 shown in fig. 14, thereby further improving the display uniformity of the display panel.
Further, referring to fig. 19, fig. 19 is a sixth circuit diagram of a pixel driving circuit according to an embodiment of the present disclosure. The pixel drive circuit 30 shown in fig. 19 differs from the pixel drive circuit 30 shown in fig. 18 in that: the drain of the third transistor T4 in the pixel driving circuit 30 shown in fig. 19 is electrically connected to the second detecting unit 104.
Specifically, the pixel drive circuit 30 shown in fig. 19 further includes a third transistor T4. The gate of the third transistor T4 is switched on the third control signal S3. The source of the third transistor T4 is electrically connected to the second node N. The drain of the third transistor T4 is electrically connected to the second detecting unit 104. The second detecting unit 104 is configured to detect a potential of the second node N under the control of the third control signal S3, and compensate the threshold voltage of the driving transistor T1 based on the potential of the second node N.
That is, the pixel driving circuit 30 shown in fig. 19 can compensate for the threshold voltage of the driving transistor T1 in addition to the pixel driving circuit 30 shown in fig. 14, thereby further improving the display uniformity of the display panel; and the wiring space of the pixel can be saved, higher aperture opening ratio can be obtained, and the pixel design with higher resolution can be realized.
Referring to fig. 20, fig. 20 is a schematic structural diagram of a display panel according to an embodiment of the present disclosure. The embodiment of the present application further provides a display panel 100, which includes the pixel driving circuit 10/20/30, and specific reference may be made to the description of the pixel driving circuit 10/20/30, which is not repeated herein.
The above are only examples of the present application, and not intended to limit the scope of the present application, and all equivalent structures or equivalent processes performed by the present application and the contents of the attached drawings, which are directly or indirectly applied to other related technical fields, are also included in the scope of the present application.

Claims (10)

1. A pixel driving circuit, comprising:
the grid electrode of the driving transistor is electrically connected to a first node, and the source electrode of the driving transistor is connected to a first power supply signal;
the anode of the light-emitting device is electrically connected to the drain electrode of the driving transistor, and the cathode of the light-emitting device is connected to a second power supply signal;
the signal input module is accessed to a data signal and a first control signal and is electrically connected to the first node, and the signal input module is used for controlling the potential of the first node based on the data signal and the first control signal;
the voltage drop detection module is connected to a second control signal and is electrically connected to the cathode of the light-emitting device, and is used for detecting an actual value of the second power signal connected to the cathode of the light-emitting device under the control of the second control signal, and acquiring a first compensation value corresponding to the second power signal and a second compensation value corresponding to the first power signal based on the actual value of the second power signal connected to the cathode of the light-emitting device, so as to adjust the actual value of the data signal connected to the signal input module;
the signal input module comprises a first transistor and a first capacitor;
the grid electrode of the first transistor is connected with the first control signal, the source electrode of the first transistor is connected with the data signal, and the drain electrode of the first transistor is electrically connected with the first node;
a first end of the first capacitor is electrically connected to the first node, and a second end of the first capacitor is electrically connected to an anode of the light emitting device; wherein, the first and the second end of the pipe are connected with each other,
the pixel driving circuit calculates the actual value of the data signal accessed to the signal input module according to the following formula: vdata = Vdata _0+ Vdata _VDD + Vdata _VSS, vdata is an actual value of the data signal accessed to the signal input module, vdata _0 is an initial value of the data signal, vdata _ VDD is the second compensation value, vdata _ VSS is the first compensation value,
vdata _ VDD = Vgs2-Vgs1, k (Vgs 1-Vth) 2 + a/c = k (Vgs 2-Vth) 2, a being the voltage difference between the actual value of the second power supply signal VSS switched into the cathode of the light emitting device D and the standard value of the second power supply signal VSS; a is a preset constant; vgs1 is a preset voltage difference between the gate and the source of the driving transistor T1; vgs2 is the actual voltage difference between the gate and source of the drive transistor T1; vth is the threshold voltage of the driving transistor T1; c is the equivalent resistance ratio of the first power signal VDD and the second power signal VSS, and k is a constant;
vdata _ VSS = a × M%, where a is a voltage difference between an actual value of the second power signal VSS connected to the cathode of the light emitting device D and a standard value of the second power signal VSS; m% is a coupling loss ratio of the first capacitor connected to the driving transistor.
2. The pixel driving circuit according to claim 1, wherein the voltage drop detection module comprises a second transistor, a second capacitor and a detection unit;
a gate of the second transistor is connected to the second control signal, a drain of the second transistor is electrically connected to the first end of the second capacitor and the detection unit, and a source of the second transistor is electrically connected to a cathode of the light emitting device; the second end of the second capacitor is electrically connected to the grounding end; the detection unit is used for detecting the actual value of the cathode of the light-emitting device accessed by the second power signal and adjusting the actual value of the signal input module accessed by the data signal based on the actual value of the cathode of the light-emitting device accessed by the second power signal.
3. The pixel driving circuit according to claim 1, wherein the voltage drop detection module comprises a second transistor, a second capacitor and a detection unit;
the grid electrode of the second transistor is connected to the second control signal, the drain electrode of the second transistor is electrically connected to the first end of the second capacitor and the detection unit, and the source electrode of the second transistor is electrically connected to the cathode of the light-emitting device; the second end of the second capacitor is electrically connected to the grounding end; the detection unit is used for detecting an actual value of the cathode of the light-emitting device accessed by the second power signal, and acquiring the first compensation value corresponding to the second power signal and the second compensation value corresponding to the first power signal based on the actual value of the cathode of the light-emitting device accessed by the second power signal, so as to adjust the actual value of the signal input module accessed by the data signal.
4. The pixel driving circuit according to claim 3, wherein the driving circuit further comprises a third transistor, a gate of the third transistor is coupled to a third control signal, a source of the third transistor is electrically connected to a second node, a drain of the third transistor is electrically connected to the first end of the second capacitor and the detecting unit, a drain of the driving transistor is electrically connected to the second node, an anode of the light emitting device is electrically connected to the second node, and a second end of the first capacitor is electrically connected to the second node;
the detecting unit is further configured to detect a potential of the second node under the control of the third control signal, and compensate the threshold voltage of the driving transistor based on the potential of the second node.
5. The pixel driving circuit according to claim 3, further comprising a third transistor, wherein a gate of the third transistor is connected to a third control signal, a source of the third transistor is electrically connected to a second node, a drain of the third transistor is electrically connected to the first end of the second capacitor and the first detecting unit, a drain of the driving transistor is electrically connected to the second node, an anode of the light emitting device is electrically connected to the second node, and a second end of the first capacitor is electrically connected to the second node;
the first detection unit is further configured to detect a potential of the second node under the control of the third control signal, and compensate the threshold voltage of the driving transistor based on the potential of the second node.
6. The pixel driving circuit according to claim 3, further comprising a third transistor, wherein a gate of the third transistor is connected to a third control signal, a source of the third transistor is electrically connected to a second node, a drain of the third transistor is electrically connected to the second detecting unit, a drain of the driving transistor is electrically connected to the second node, an anode of the light emitting device is electrically connected to the second node, and a second end of the first capacitor is electrically connected to the second node;
the second detection unit is configured to detect a potential of the second node under control of the third control signal, and compensate the threshold voltage of the driving transistor based on the potential of the second node.
7. The pixel driving circuit according to claim 1, wherein the pixel driving circuit calculates the actual value of the data signal accessing the signal input module according to the following formula: vdata = Vdata _0+ a, where Vdata is an actual value of the data signal connected to the signal input module, vdata _0 is an initial value of the data signal, and a is a voltage difference between an actual value of the second power signal connected to the cathode of the light emitting device and a standard value of the second power signal.
8. The pixel driving circuit according to claim 1, wherein the pixel driving circuit calculates the actual value of the data signal accessing the signal input module according to the following formula: vdata = Vdata _0+ a + B% (1-B%), wherein Vdata is an actual value of the data signal connected to the signal input module, vdata _0 is an initial value of the data signal, a is a voltage difference between an actual value of the second power signal connected to the cathode of the light emitting device and a standard value of the second power signal, and B% is a coupling loss coefficient in the pixel driving circuit.
9. The pixel driving circuit according to claim 1, wherein the light emitting device is an organic light emitting diode.
10. A display panel comprising the pixel drive circuit according to any one of claims 1 to 9.
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