CN112164376A - Display device and control method thereof - Google Patents
Display device and control method thereof Download PDFInfo
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- CN112164376A CN112164376A CN202011101619.3A CN202011101619A CN112164376A CN 112164376 A CN112164376 A CN 112164376A CN 202011101619 A CN202011101619 A CN 202011101619A CN 112164376 A CN112164376 A CN 112164376A
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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]
- G09G3/3225—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] using an active matrix
Abstract
The application provides a display device and a control method thereof, wherein threshold voltages of driving transistors of a plurality of internal driving circuits are obtained through calculation according to sensing voltages of drain electrodes of the driving transistors of the plurality of internal driving circuits and preset lookup table data, the preset lookup table data comprises data corresponding to the preset threshold voltages and the preset drain voltage mapping relation, and the threshold voltages of P-type driving transistors connected with source electrodes and power signal lines are obtained and externally compensated according to the threshold voltages of the driving transistors of the plurality of internal driving circuits.
Description
Technical Field
The present disclosure relates to display technologies, and particularly to a display device and a control method thereof.
Background
An Active Matrix Organic Light Emitting Diode (AMOLED) is expected to prohibit the lcd from becoming the mainstream choice of the next generation display due to its high contrast, wide viewing angle, fast response speed and flexible display.
At present, as shown in fig. 1, which is a schematic diagram of a source of a P-type driving transistor connected to a power signal line VDD, since the driving transistor of a large-sized oled panel is a P-type thin film transistor and the source of the P-type thin film transistor is connected to the power signal line VDD, a power signal input by the power signal line VDD makes the source voltage of the P-type driving transistor undetectable, and cannot capture the threshold voltage of the driving transistor if the driving transistor is an N-type thin film transistor.
Therefore, it is necessary to provide a technical solution to achieve the threshold voltage acquisition and compensation when the driving transistor is a P-type transistor.
Disclosure of Invention
The present application provides a display device and a control method thereof to achieve the acquisition of threshold voltages of driving transistors of a plurality of internal driving circuits and external compensation.
To achieve the above object, the present application provides a display apparatus including a driving circuit including a plurality of internal driving circuits and an external compensation circuit electrically connected to the plurality of internal driving circuits,
each internal driving circuit comprises a driving transistor, the source electrode of the driving transistor is connected with a power signal line, the drain electrode of the driving transistor is electrically connected with at least one light-emitting device, a fixed reference voltage is written into the grid electrode of the driving transistor in a detection stage, and the driving transistor is a P-type transistor;
the external compensation circuit includes:
the memory is used for storing preset lookup table data and threshold voltage lookup table data; and
the processor is electrically connected with the memory, the drains of the driving transistors of the plurality of internal driving circuits, and the gates of the driving transistors of the plurality of internal driving circuits, and is configured to obtain a sensing voltage of the drains of the plurality of driving transistors at the detection stage, obtain the preset lookup table data from the memory, obtain threshold voltage lookup table data according to the sensing voltage of the drains of the plurality of driving transistors and the preset lookup table data, and output the threshold voltage lookup table data to the memory, where the preset lookup table data includes data corresponding to a mapping relationship between a preset threshold voltage and a preset drain voltage, and the threshold voltage lookup table data includes threshold voltages of the plurality of driving transistors; the processor is further configured to obtain original display data and the threshold voltage look-up table data from the memory at a threshold voltage compensation and data writing stage, calculate updated display data according to the original display data and the threshold voltage look-up table data, and transmit the updated display data to gates of the driving transistors of the plurality of internal driving circuits.
In the display device, in the detection stage, the processor is configured to calculate, based on the preset lookup table data, a threshold voltage corresponding to a sensing voltage of the drain of the driving transistor by linear interpolation, so as to obtain the threshold voltage lookup table data.
In the display device, in the threshold voltage compensation and data writing stage, the processor is configured to sum the original display data and the threshold voltage of the driving transistor of the internal driving circuit corresponding to the original display data to obtain the updated display data.
In the above display device, each of the internal drive circuits further includes:
a light emission control transistor connected between the drain of the driving transistor and the light emitting device;
the switch transistor is connected between the grid electrode of the driving transistor and a data line, and the data line is electrically connected with the processor;
a sensing transistor connected between a sensing line and a drain of the driving transistor, the sensing line being electrically connected to the processor; and
a capacitor having one end connected between the power supply signal line and the source of the driving transistor and the other end connected to the gate of the driving transistor;
the external compensation circuit further includes:
an analog-to-digital converter connected between the sense line and the processor; and
a digital-to-analog converter coupled between the data line and the processor.
In the above display device, the driving transistor is a low temperature polysilicon transistor.
A control method of a display apparatus including a driving circuit including a plurality of internal driving circuits and an external compensation circuit electrically connected to the plurality of internal driving circuits,
each internal driving circuit comprises a driving transistor, the source electrode of the driving transistor is connected with a power signal line, the drain electrode of the driving transistor is electrically connected with at least one light-emitting device, and the driving transistor is a P-type transistor;
the external compensation circuit comprises a processor and a memory, wherein the processor is electrically connected with the memory, the drains of the driving transistors of the plurality of internal driving circuits and the gates of the driving transistors of the plurality of internal driving circuits;
the control method comprises the following steps:
in a detection stage, the same fixed reference voltage is input into the grid electrodes of the driving transistors of the plurality of internal driving circuits; the processor acquires sensing voltages of the drains of the plurality of driving transistors and preset lookup table data from the memory, acquires threshold voltage lookup table data according to the sensing voltages of the drains of the plurality of driving transistors and the preset lookup table data, and outputs the threshold voltage lookup table data to the memory, wherein the preset lookup table data comprises data corresponding to a mapping relation between preset threshold voltages and preset drain voltages, and the threshold voltage lookup table data comprises the threshold voltages of the plurality of driving transistors; the memory acquires and stores the threshold voltage look-up table data;
in the threshold voltage compensation and data writing stages, the processor acquires original display data and the threshold voltage look-up table data from the memory, obtains updated display data according to the original display data and the threshold voltage look-up table data, and transmits the updated display data to the gates of the driving transistors of the plurality of internal driving circuits.
In the control method of the display device, the obtaining of the threshold voltage look-up table data according to the sensing voltages of the drains of the plurality of driving transistors and the preset look-up table data includes:
and the processor calculates threshold voltages corresponding to the sensing voltages of the drains of the plurality of driving transistors through linear interpolation based on the preset lookup table data to obtain the threshold voltage lookup table data.
In the control method of the display device, the obtaining of the updated display data according to the original display data and the threshold voltage look-up table data includes the following steps:
the processor sums the original display data and the threshold voltage of the driving transistor of the internal driving circuit corresponding to the original display data to obtain the updated display data.
In the control method of the display device described above, each of the internal drive circuits further includes:
a light emission control transistor connected between the drain of the driving transistor and the light emitting device;
the switch transistor is connected between the grid electrode of the driving transistor and a data line, and the data line is electrically connected with the processor;
a sensing transistor connected between a sensing line and a drain of the driving transistor, the sensing line being electrically connected to the processor; and
a capacitor having one end connected between the power supply signal line and the source of the driving transistor and the other end connected to the gate of the driving transistor;
the external compensation circuit further includes:
an analog-to-digital converter connected between the sense line and the processor; and
a digital-to-analog converter coupled between the data line and the processor.
In the control method of the display device, the driving transistor is a low-temperature polysilicon transistor.
In the control method of the display device, the detection stage is a shutdown stage of the display device.
Has the advantages that: the application provides a display device and a control method thereof, wherein threshold voltages of driving transistors of a plurality of internal driving circuits are obtained through calculation according to sensing voltages of drain electrodes of the driving transistors of the plurality of internal driving circuits and preset lookup table data, the preset lookup table data comprises data corresponding to preset threshold voltages and preset drain voltage mapping relations, and external compensation of the threshold voltages of P-type driving transistors of which source electrodes are connected with a power signal line is achieved according to the threshold voltages of the driving transistors of the plurality of internal driving circuits. And the detection of the threshold voltage of the driving transistors of the plurality of internal driving circuits is carried out when the display device is shut down, so that the threshold voltage of the P-type driving transistor can be rapidly acquired and compensated.
Drawings
FIG. 1 is a diagram illustrating a source of a P-type driving transistor connected to a power signal line;
FIG. 2 is a circuit diagram of a driving circuit according to an embodiment of the present application;
fig. 3 is a driving timing diagram of the driving circuit shown in fig. 2.
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 embodiments described are only 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.
The application provides a display device, which comprises an organic light emitting diode display panel. The organic light emitting diode display panel includes a driving circuit and a plurality of light emitting devices OLEDs. The driving circuit is used for driving the plurality of light emitting devices OLED to emit light. The light emitting device OLED is an organic light emitting diode.
Please refer to fig. 2, which is a circuit diagram of a driving circuit according to an embodiment of the present application. The driving circuit 100 includes a plurality of internal driving circuits 100a and an external compensation circuit 100b electrically connected to the plurality of internal driving circuits 100 a. Each internal driving circuit 100a is electrically connected to at least one light emitting device OLED to drive the at least one light emitting device OLED to emit light. A row of internal driving circuits 100a is electrically connected to an external compensation circuit 100 b.
Each internal driving circuit 100a includes a driving transistor T1, a switching transistor T2, a sensing transistor T3, a light emission controlling transistor T4, a capacitor C, and a switch K. The driving transistor T1, the switching transistor T2, the emission control transistor T4, and the sensing transistor T3 are all P-type transistors.
The source of the driving transistor T1 is connected to the power signal line, and the drain of the driving transistor T1 is electrically connected to at least one light emitting device OLED. The driving transistor T1 is used to drive the light emitting device OLED to emit light.
Specifically, the source of the driving transistor T1 is connected to the first power supply signal line VDD and one end of the capacitor C, the gate of the driving transistor T1 is connected to the drain of the switching transistor T2 and the other end of the capacitor C, and the drain of the driving transistor T1 is connected to the source of the sensing transistor T3 and the source of the light emission controlling transistor T4. The first power signal line VDD is used for inputting a first power signal.
Compared with the conventional transistor with a metal oxide active layer, which is a transistor in the prior art, which easily causes the threshold voltage of the driving transistor to shift under the stress, the driving transistor T1 in this embodiment is a transistor with a low temperature polysilicon active layer, which can prevent the threshold voltage of the driving transistor T1 from shifting significantly due to the continuous stress.
In the detection phase, the same fixed reference voltage is written into the gates of the driving transistors T1 of the internal driving circuits 100a, the first power signal is input to the sources of the driving transistors T1, and the drains of the driving transistors T1 have corresponding drain voltages.
The switch transistor T2 is connected between the gate of the driving transistor T1 and the Data line Data, and the Data line Data is electrically connected to the processor 101. The switching transistor T2 is used to control whether the Data signal inputted from the Data line Data is written to the gate of the driving transistor T1.
Specifically, the source of the switching transistor T2 is connected to the Data line Data, which is electrically connected to the processor 101; the drain of the switching transistor T2 is connected to the gate of the driving transistor T1 and the other end of the capacitor C; the gate of the switching transistor T2 is connected to the first Scan signal line Scan 1. The switching transistor T2 may be any one of a low temperature polysilicon transistor or a metal oxide transistor. The first Scan signal line Scan1 is used to input a first Scan signal.
The light emission controlling transistor T4 is connected between the drain of the driving transistor T1 and the light emitting device OLED. The light emission controlling transistor T4 is used to control whether the driving current of the driving transistor T1 is written to the light emitting device OLED.
Specifically, the gate of the light emission controlling transistor T4 is connected to the light emission controlling signal line EM, the source of the light emission controlling transistor T4 is connected to the drain of the driving transistor T1 and the source of the sensing transistor T3, the drain of the light emission controlling transistor T4 is connected to the anode of the light emitting device OLED, and the cathode of the light emitting device OLED is connected to the second power signal line VSS. The second power signal line VSS is used for inputting a second power signal. The emission control signal line EM is used for inputting an emission control signal.
In the embodiment, the light-emitting control transistor T4 is a low-temperature polysilicon transistor, which prevents the light-emitting control transistor T4 from drifting in threshold voltage due to long-term stress, and prevents the light-emitting control transistor T4 from being turned on due to the drifting in threshold voltage to cause current leakage and affect the sensing of the sensing voltage of the drain of the driving transistor T1 when the sensing voltage of the drain of the driving transistor T1 is detected.
The sensing transistor T3 is connected between the sensing line Sense and the drain of the driving transistor T1, and the sensing line Sense is electrically connected to the processor 101. The sensing transistor T3 is used to control whether the processor 101 obtains a sensing voltage of the drain of the driving transistor T1.
Specifically, the source of the sensing transistor T3 is connected to the drain of the driving transistor T1 and the source of the light emission controlling transistor T4, the drain of the sensing transistor T3 is connected to the sensing line Sense, and the gate of the sensing transistor T3 is connected to the second Scan signal line Scan 2. The second Scan signal line Scan2 is used to input a second Scan signal. The sensing line Sense is electrically connected to the processor 101. The sensing transistor T3 may be at least one of a metal oxide transistor or a low temperature polysilicon transistor.
One end of the capacitor C is connected between the first power supply signal line VDD and the source of the driving transistor T1, and the other end of the capacitor C is connected to the gate of the driving transistor T1. The capacitor C is used to maintain the voltage of the gate of the driving transistor T1 during the light emitting period to ensure that the light emitting device OLED emits light for one frame time.
The switch K is connected between the sensing line Sense and the reference voltage signal line Vref 2. The reference voltage signal line Vref2 is used to input a second fixed reference voltage, and the reset of the drain of the driving transistor T1 is realized through the turned-on switch K and the turned-on sensing transistor T3, so as to avoid the influence of the residual charge on the drain of the driving transistor T1 when the sensing voltage on the drain of the driving transistor T1 is sensed in the detection phase on the accuracy of the sensing voltage on the drain of the driving transistor T1.
The external compensation circuit 100b comprises an analog-to-digital converter ADC, a processor 101, a memory 102 and a digital-to-analog converter DAC.
The analog-to-digital converter ADC is connected between the sensing line Sense and the processor 101, and is configured to perform analog-to-digital conversion on the sensing voltage at the drain of the driving transistor T1 of the internal driving circuits 100a during the detection phase, and transmit the sensing voltage to the processor. Specifically, each analog-to-digital converter ADC is connected to a sensing line Sense of a row of internal driving circuits 100a to detect a sensing voltage at the drain of the driving transistor T1 of the row of internal driving circuits 100a during the detection phase. The analog-to-digital converter ADC is connected to the processor 101 to transmit the sensing voltage of the drain of the driving transistor T1 of one column of the internal driving circuit 100a to the processor 101.
The processor 101 is electrically connected to the memory 102, the analog-to-digital converter ADC and the digital-to-analog converter DAC. The processor 101 obtains the sensing voltage of the drains of the driving transistors T1 from the ADC and the preset lookup table data from the memory 102, obtains the threshold voltage lookup table data according to the sensing voltage of the drains of the driving transistors T1 and the preset lookup table data, and outputs the threshold voltage lookup table data to the memory 102. The preset lookup table data includes data corresponding to a mapping relationship between a preset threshold voltage and a preset drain voltage, and the threshold voltage lookup table data includes threshold voltages of the driving transistors T1. The processor 101 may be a Field Programmable Gate Array (FPGA).
Specifically, the processor 101 calculates threshold voltages corresponding to the sensing voltages of the drains of the plurality of driving transistors T1 by linear interpolation based on preset lookup table data, resulting in threshold voltage lookup table data. The preset look-up table data is shown in table 1. For example, when the sensing voltage is 3.4V, the threshold voltage of the driving transistor T1 with the sensing voltage of 3.4V is-0.1303V by linear interpolation calculation.
It should be noted that the preset lookup table data is obtained based on external experiments. Wherein, the objects of the external experiment are: 26 test driving transistors with different threshold voltages, the test driving transistors are P-type transistors. The conditions of the external experiment were: the source of the test driving transistor is connected to the test power signal line VDD ', the power signal (4.5V) input by the test power signal line VDD' is the same as the first power signal input by the first power signal line VDD in the internal driving circuit 100a, the test fixed reference voltage (2V) input by the gate of the test driving transistor is the same as the fixed reference voltage input by the gate of the driving transistor T1 in the internal driving circuit 100a at the detection stage, the preset drain voltage of the drain of the test driving transistor is detected, and the preset threshold voltage corresponding to the preset drain voltage of each test driving transistor is obtained from the transfer characteristic curve of the test driving transistor. It is understood that the more data in the preset look-up table data, the more the accuracy of the threshold voltage in the threshold voltage look-up table data can be improved.
TABLE 1 Preset look-up Table data
In the threshold voltage compensation and data writing stage, the processor 101 obtains the original display data and the threshold voltage look-up table data from the memory 102, calculates the updated display data according to the original display data and the threshold voltage look-up table data, and transmits the updated display data to the gates of the driving transistors T1 of the plurality of internal driving circuits 100 a.
Specifically, in the threshold voltage compensation and data writing stage, the processor 101 acquires original display data Vdata including a data voltage to be displayed of the light emitting device OLED and the like from the outside, and acquires threshold voltage lookup table data from the memory 102, and sums the original display data Vdata and the threshold voltage Vth of the driving transistor T1 of the driving circuit corresponding to the original display data Vdata to obtain updated display data Vdata'. For example, the original display data Vdata to be displayed by one internal driving circuit 100a is 6V, the threshold voltage of the driving transistor T1 of the internal driving circuit 100a is-2.0V, and the updated display data is 4V.
The digital-to-analog converter DAC is connected between the Data line Data and the processor 101. In the threshold voltage compensation and Data writing phases, the DAC obtains the updated display Data from the processor 101, performs digital-to-analog conversion on the updated display Data, and outputs the updated display Data to the Data line Data, and the Data line Data outputs the updated display Data to the gate of the driving transistor T1.
The memory 102 is electrically connected to the processor 101 and is configured to store preset look-up table data and threshold voltage look-up table data.
In the display device of the present embodiment, the sensing voltages of the corresponding drains when the sources and the gates of the driving transistors of the plurality of internal driving circuits of the display device have the same voltage are detected in the detection stage, and the threshold voltages of the driving transistors of the plurality of internal driving circuits of the entire display device are obtained based on the preset lookup table data and the sensing voltage calculation of the drains of the driving transistors, so as to obtain the threshold voltage of the P-type driving transistor connected to the source signal line, and provide a data basis for external compensation of the threshold voltage of the P-type driving transistor.
Please refer to fig. 3, which is a driving timing diagram of the driving circuit shown in fig. 2. The control method of the display device comprises the following steps:
in the initialization stage T1, the switch K is turned on, the reference voltage signal line Vref2 writes the second fixed reference voltage, the second Scan signal line Scan2 inputs the low level signal, and the sensing transistor T3 is turned on; a high-level signal is input to the first Scan signal line Scan1, and the switching transistor T2 is turned off; the emission control signal line EM receives a high-level signal, and the emission control transistor T4 is turned off. The second fixed reference voltage is transmitted to the drain of the driving transistor T1 through the turned-on switch K and the turned-on sensing transistor T3 to initialize the drain of the driving transistor T1, so that the sensing voltages of the drains of the driving transistors T1 of the plurality of internal driving circuits 100a on the display device are the same before detection, and the residual charges of the drain of the driving transistor T1 are prevented from affecting the detection of the sensing voltage of the drain of the driving transistor T1.
In the detection period T2, the first Scan signal line Scan1 inputs a low level signal, and the switch transistor T2 is turned on; the plurality of Data lines Data connected to the plurality of switching transistors T2 are all inputted with the first fixed reference voltage Vref, and the first fixed reference voltage Vref is transmitted to the gates of the driving transistors T1 of the plurality of internal driving circuits 100a through the turned-on switching transistor T2, the sources of the driving transistors T1 of the plurality of internal driving circuits 100a are all inputted with the first power signal, and the driving transistors T1 of the plurality of internal driving circuits 100a are all turned-on. The second Scan signal line Scan2 inputs a low level signal, the sensing transistor T3 is turned on, the analog-to-digital converter ADC senses the sensing voltage at the drain of the driving transistor T1 of the internal driving circuits 100a and outputs the sensing voltage to the processor 101 after analog-to-digital conversion; the processor 101 obtains the sensing voltages of the drains of the plurality of driving transistors T1 and preset lookup table data from the memory 102, obtains threshold voltage lookup table data according to the sensing voltages of the drains of the plurality of driving transistors T1 and the preset lookup table data, and outputs the threshold voltage lookup table data to the memory 102 to store the threshold voltages of the plurality of driving transistors T1 in the memory 102. The emission control signal line EM receives a high-level signal, and the emission control transistor T4 is turned off.
In the embodiment, since the time consumed by the detection stage is 10-20 microseconds, and the display time of one frame of picture is 16.67 microseconds, the detection stage of the present application is in the shutdown stage of the display device, which is beneficial to avoiding the detection stage from occupying too much display time, and is beneficial to the rapid compensation of the threshold voltage of the subsequent driving transistor.
In this embodiment, the processor 101 calculates the threshold voltages corresponding to the sensing voltages of the drains of the plurality of driving transistors T1 by linear interpolation based on the preset lookup table data, to obtain the threshold voltage lookup table data.
In the threshold voltage compensation and data writing phase T3, the first Scan signal line Scan1 inputs a low level signal, and the switching transistor T2 is turned on; the second Scan signal line Scan2 inputs a high level signal, and the sensing transistor T3 is turned off; the emission control signal line EM receives a high-level signal, and the emission control transistor T4 is turned off. The processor 101 obtains original display data from the outside, obtains threshold voltage look-up table data from the memory 102, obtains updated display data according to the original display data and the threshold voltage look-up table data, and transmits the updated display data to the digital-to-analog converter DAC; the digital-to-analog converter DAC acquires the updated display Data, and outputs the updated display Data to the gates of the driving transistors T1 of the plurality of internal driving circuits 101a through the Data lines Data after digital-to-analog conversion.
Specifically, the processor 101 sums the original display data and the threshold voltage of the driving transistor T1 of the internal driving circuit 100a corresponding to the original display data, resulting in updated display data. Each of the internal driving circuits 100a drives at least one light emitting device OLED displaying one original display data correspondingly.
In the light emitting period T4, the first Scan signal line Scan1 inputs a high level signal, and the switching transistor T2 is turned off; the second Scan signal line Scan2 inputs a high level signal, and the sensing transistor T3 is turned off; the light emission control signal line EM inputs a low level signal, the light emission control transistor T4 is turned on, the driving transistor T1 is turned on under the effect of updating display data, and a driving current is output to the light emitting device OLED through the turned-on light emission control transistor T4, and the light emitting device OLED emits light.
In the light emitting period T4, the driving current of the driving transistor T1 is I, and the calculation formula of the driving current I is as follows:
where u is the carrier mobility of the driving transistor T1, W is the width of the channel of the driving transistor T1, L is the length of the communication of the driving transistor T1, Vgs is the voltage difference between the gate and the source of the driving transistor T1, Vth is the threshold voltage of the driving transistor T1, and cox is the channel capacitance per unit area.
As can be seen from the calculation formula of the driving current I, the driving current I is independent of the threshold voltage of the driving transistor T1, and the threshold voltage of the driving transistor T1 is compensated.
The above description of the embodiments is only for assisting understanding of the technical solutions and the core ideas thereof; those of ordinary skill in the art will understand that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications or substitutions do not depart from the spirit and scope of the present disclosure as defined by the appended claims.
Claims (11)
1. A display device comprises a driving circuit and a plurality of light emitting devices, wherein the driving circuit comprises a plurality of internal driving circuits and an external compensation circuit electrically connected with the internal driving circuits,
each internal driving circuit comprises a driving transistor, the source electrode of the driving transistor is connected with a power signal line, the drain electrode of the driving transistor is electrically connected with at least one light-emitting device, a fixed reference voltage is written into the grid electrode of the driving transistor in a detection stage, and the driving transistor is a P-type transistor;
the external compensation circuit includes:
the memory is used for storing preset lookup table data and threshold voltage lookup table data; and
the processor is electrically connected with the memory, the drains of the driving transistors of the plurality of internal driving circuits, and the gates of the driving transistors of the plurality of internal driving circuits, and is configured to obtain a sensing voltage of the drains of the plurality of driving transistors at the detection stage, obtain the preset lookup table data from the memory, obtain threshold voltage lookup table data according to the sensing voltage of the drains of the plurality of driving transistors and the preset lookup table data, and output the threshold voltage lookup table data to the memory, where the preset lookup table data includes data corresponding to a mapping relationship between a preset threshold voltage and a preset drain voltage, and the threshold voltage lookup table data includes threshold voltages of the plurality of driving transistors; the processor is further configured to obtain original display data and the threshold voltage look-up table data from the memory at a threshold voltage compensation and data writing stage, calculate updated display data according to the original display data and the threshold voltage look-up table data, and transmit the updated display data to gates of the driving transistors of the plurality of internal driving circuits.
2. The display device according to claim 1, wherein in the detection phase, the processor is configured to calculate threshold voltages corresponding to sensing voltages of drains of the plurality of driving transistors by linear interpolation based on the preset lookup table data to obtain the threshold voltage lookup table data.
3. The display device according to claim 1, wherein in the threshold voltage compensation and data writing phase, the processor is configured to sum the original display data and the threshold voltage of the driving transistor of the internal driving circuit corresponding to the original display data to obtain the updated display data.
4. The display device according to claim 1, wherein each of the internal driving circuits further comprises:
a light emission control transistor connected between the drain of the driving transistor and the light emitting device;
the switch transistor is connected between the grid electrode of the driving transistor and a data line, and the data line is electrically connected with the processor;
a sensing transistor connected between a sensing line and a drain of the driving transistor, the sensing line being electrically connected to the processor; and
a capacitor having one end connected between the power supply signal line and the source of the driving transistor and the other end connected to the gate of the driving transistor;
the external compensation circuit further includes:
an analog-to-digital converter connected between the sense line and the processor; and
a digital-to-analog converter coupled between the data line and the processor.
5. The display device according to claim 1, wherein the driving transistor is a low temperature polysilicon transistor.
6. A control method of a display device, the display device comprises a driving circuit and a plurality of light emitting devices, the driving circuit comprises a plurality of internal driving circuits and an external compensation circuit electrically connected with the internal driving circuits,
each internal driving circuit comprises a driving transistor, the source electrode of the driving transistor is connected with a power signal line, the drain electrode of the driving transistor is electrically connected with at least one light-emitting device, and the driving transistor is a P-type transistor;
the external compensation circuit comprises a processor and a memory, wherein the processor is electrically connected with the memory, the drains of the driving transistors of the plurality of internal driving circuits and the gates of the driving transistors of the plurality of internal driving circuits;
the control method comprises the following steps:
in a detection stage, the same fixed reference voltage is input into the grid electrodes of the driving transistors of the plurality of internal driving circuits; the processor acquires sensing voltages of the drains of the plurality of driving transistors and preset lookup table data from the memory, acquires threshold voltage lookup table data according to the sensing voltages of the drains of the plurality of driving transistors and the preset lookup table data, and outputs the threshold voltage lookup table data to the memory, wherein the preset lookup table data comprises data corresponding to a mapping relation between preset threshold voltages and preset drain voltages, and the threshold voltage lookup table data comprises the threshold voltages of the plurality of driving transistors; the memory acquires and stores the threshold voltage look-up table data;
in the threshold voltage compensation and data writing stages, the processor acquires original display data and the threshold voltage look-up table data from the memory, obtains updated display data according to the original display data and the threshold voltage look-up table data, and transmits the updated display data to the gates of the driving transistors of the plurality of internal driving circuits.
7. The method according to claim 6, wherein the obtaining of the threshold voltage look-up table data from the sensing voltages of the drains of the plurality of driving transistors and the preset look-up table data comprises:
and the processor calculates threshold voltages corresponding to the sensing voltages of the drains of the plurality of driving transistors through linear interpolation based on the preset lookup table data to obtain the threshold voltage lookup table data.
8. The method of claim 6, wherein the step of obtaining updated display data from the original display data and the threshold voltage look-up table data comprises the steps of:
the processor sums the original display data and the threshold voltage of the driving transistor of the internal driving circuit corresponding to the original display data to obtain the updated display data.
9. The control method of a display device according to claim 6, wherein each of the internal drive circuits further comprises:
a light emission control transistor connected between the drain of the driving transistor and the light emitting device;
the switch transistor is connected between the grid electrode of the driving transistor and a data line, and the data line is electrically connected with the processor;
a sensing transistor connected between a sensing line and a drain of the driving transistor, the sensing line being electrically connected to the processor; and
a capacitor having one end connected between the power supply signal line and the source of the driving transistor and the other end connected to the gate of the driving transistor;
the external compensation circuit further includes:
an analog-to-digital converter connected between the sense line and the processor; and
a digital-to-analog converter coupled between the data line and the processor.
10. The method according to claim 6, wherein the driving transistor is a low-temperature polysilicon transistor.
11. The method as claimed in claim 6, wherein the detecting stage is a power-off stage of the display device.
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