WO2021103408A1 - Circuit de compensation intra-pixel et appareil d'affichage luminescent - Google Patents

Circuit de compensation intra-pixel et appareil d'affichage luminescent Download PDF

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Publication number
WO2021103408A1
WO2021103408A1 PCT/CN2020/086610 CN2020086610W WO2021103408A1 WO 2021103408 A1 WO2021103408 A1 WO 2021103408A1 CN 2020086610 W CN2020086610 W CN 2020086610W WO 2021103408 A1 WO2021103408 A1 WO 2021103408A1
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Prior art keywords
tft
control signal
light
terminal
switch
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PCT/CN2020/086610
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English (en)
Chinese (zh)
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黄洪涛
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南京中电熊猫液晶显示科技有限公司
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Publication of WO2021103408A1 publication Critical patent/WO2021103408A1/fr

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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]
    • 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]

Definitions

  • the present application relates to the technical field of display panels, and in particular to a compensation circuit within a pixel.
  • Self-luminous types include Organic Light Emitting Diode (OLED) and Quantum Dot Light Emitting Diode (QLED) , Micro-Light Emitting Diode (Micro-LED), self-luminous displays have natural advantages in these aspects.
  • OLED Organic Light Emitting Diode
  • QLED Quantum Dot Light Emitting Diode
  • Micro-LED Micro-Light Emitting Diode
  • the light-emitting brightness is positively correlated with the applied voltage and current.
  • the relationship between luminous brightness and voltage will change due to factors such as ambient temperature and usage time. Therefore, it is difficult to control the brightness uniformity and stability of the self-luminous display by adopting a voltage-driven light-emitting element method.
  • the brightness of the light-emitting element is roughly proportional to the current it applies, and it is not susceptible to interference from other factors. Therefore, self-luminous displays usually adopt a current-driven design.
  • the current for driving the light-emitting element is provided by the TFT backplane, including low temperature poly-silicon thin film transistor (LTPS TFT) and oxide semiconductor TFT.
  • LTPS TFT low temperature poly-silicon thin film transistor
  • oxide semiconductor TFT oxide semiconductor TFT.
  • the characteristics of TFTs such as threshold voltage Vth or mobility, are prone to deviation or drift, causing deviation or drift in driving current, and affecting display uniformity and lifetime. Therefore, a pixel circuit for self-luminous display is usually provided with a circuit to compensate for the deviation or drift of TFT characteristics to improve display uniformity and lifetime problems.
  • the pixel compensation circuit can usually adopt two control modes: current control mode and voltage control mode.
  • the current control mode can simultaneously compensate the threshold voltage and mobility of the TFT;
  • the voltage control mode usually compensates the threshold voltage of the TFT.
  • the current control mode has the following two problems: (1) The control current is relatively weak, and the design requirements for the integrated circuit (IC) are very high; (2) Due to the influence of parasitic capacitance, the pixel compensation circuit of the current control mode It takes a relatively long setting time to achieve the compensation effect. Therefore, the current pixel compensation circuit mostly adopts a voltage control mode.
  • FIG. 1 shows an existing uncompensated pixel circuit, which includes a switching TFT 1, a driving TFT 2, and a storage capacitor 3.
  • the switching TFT 1 is controlled by the scanning signal Scan, and the data signal Vdata is input to the gate control terminal of the driving TFT 2.
  • the driving TFT 2 is controlled by the voltage of the gate control terminal, and under the action of the power supply ELVDD, it outputs a driving current, and the driving current flows through the light-emitting element 4 to emit light.
  • the storage capacitor 3 is connected to the gate control terminal of the driving TFT 2 and the power source ELVDD, and is used to maintain the voltage of the gate control terminal of the driving TFT 2 to prevent the voltage of the gate control terminal of the driving TFT 2 from changing due to leakage during a refresh period.
  • the uncompensated pixel circuit does not compensate the characteristics of the TFT, the current flowing through the light-emitting element will be changed by the characteristic deviation and drift of the driving TFT, resulting in poor display uniformity and short life of the display.
  • the purpose of the present application is to provide a compensation circuit in a pixel and a self-luminous display device, so as to avoid the problem of brightness reduction caused by the aging of the light-emitting device, and to improve the lifespan of the display device.
  • the application provides a compensation circuit in a pixel, which is connected to a light-emitting element; the light-emitting element is located between a first power source and a second power source, and the light-emitting element is controlled by a first light-emitting control signal and a second light-emitting control signal;
  • the first driving TFT connected to the light-emitting element, the first switching TFT located at the intersection of the scan line and the data line, the second switching TFT and the third switching TFT connected to the first light-emitting control signal, and the second light-emitting control signal
  • the fourth switching TFT, the fifth switching TFT connected to the first driving TFT, and the storage capacitor, wherein the access point of the pixel unit is located at the intersection of the first switching TFT, the fourth switching TFT and the storage capacitor;
  • scan line Provides a first scan control signal and a second scan control signal, the fifth switch TFT is connected to the first scan control signal, and the first switch TFT and the third switch TFT are
  • control terminal of the first driving TFT is connected to the first terminal of the storage capacitor, the first channel terminal of the third switching TFT, and the second channel terminal of the fifth switching TFT; the first channel terminal of the first driving TFT is connected to the second channel terminal.
  • the second path end of the switching TFT and the second path end of the third switching TFT; the second path end of the first driving TFT is connected to the anode of the light-emitting element.
  • control terminal of the first switch TFT is connected to the second scan control signal
  • first channel terminal of the first switch TFT is connected to the data line
  • second channel terminal of the first switch TFT is connected to the second terminal of the storage capacitor and the fourth switch TFT second channel end.
  • control terminal of the second switching TFT is connected to the first light-emitting control signal, the first path terminal of the second switching TFT is connected to the first power supply; the control terminal of the third switching TFT is connected to the second scanning control signal; The control terminal is connected to the second light-emitting control signal, the first channel terminal of the fourth switch TFT is connected to the reference voltage; the control terminal of the fifth switch TFT is connected to the first scan control signal, and the first channel terminal of the fifth switch TFT is connected to the first power supply or Reference voltage.
  • the first scan control signal and the second light-emitting control signal are input to a high level, and the second scan control signal and the first light-emission control signal are input to a low level.
  • the fifth switching TFT is turned on, the second switching TFT and the third switching TFT are turned off, the light emitting element stops emitting light, and the control terminal of the first driving TFT is charged and reset by the fifth switching TFT.
  • the second scan control signal and the data voltage are input to a high level, and the first scan control signal, the first light emission control signal, and the second light emission control signal are input to a low level.
  • the fifth switch The TFT, the second switching TFT, and the fourth switching TFT are off, the first switching TFT, the third switching TFT, and the first driving TFT are in the on state, and the gate and drain of the first driving TFT are connected together to form a diode connection ,
  • the voltage of the control terminal of the first driving TFT is discharged to the light-emitting element through the first driving TFT, until the voltage between the gate and drain of the first driving TFT drops to the threshold voltage, the first driving TFT is turned off, and the discharge stops.
  • the threshold voltage of the driving TFT is successfully extracted to the control terminal of the first driving TFT and saved by the storage capacitor; at the same time, the data voltage is written into the access point of the pixel unit through the first switching TFT.
  • the first light-emitting control signal is input to a high level, and the second light-emission control signal, the first scan control signal, the second scan control signal, and the data voltage are input to a low level.
  • the first switch The TFT, the third switch TFT, the fourth switch TFT, and the fifth switch TFT are turned off, the voltage of the access point of the pixel unit and the control terminal of the first driving TFT are locked, and the voltage difference across the storage capacitor is also locked; at the same time , The second switch TFT is turned on and enters the light-emitting preparation stage.
  • the first light-emitting control signal and the second light-emitting control signal are input to a high level, the first scan control signal, the second scan control signal, and the data voltage are input to a low level, and the fourth switch TFT is turned on,
  • the voltage of the access point of the pixel unit changes from the data voltage to the reference voltage.
  • the voltage change of the access point of the pixel unit is coupled to the control terminal of the first driving TFT.
  • the first driving TFT is turned on, and the first power supply and the second power supply are different.
  • a conductive path is formed between, and current flows through the light-emitting element to emit light.
  • the present application also provides a compensation circuit within a pixel, which is connected to a light-emitting element; the light-emitting element is located between a first power source and a second power source, and the light-emitting element is controlled by a first light-emitting control signal; and it includes connection with the light-emitting element
  • a fifth switching TFT and a storage capacitor connected to the first driving TFT, wherein the access point of the pixel unit is located at the intersection of the first switching TFT, the fourth switching TFT and the storage capacitor;
  • the scan line provides the first scan control Signal and the second scan control signal, the fifth switch TFT is connected with the first scan control signal, and the first switch TFT and the third switch TFT are connected with the second scan control signal; where
  • control terminal of the first driving TFT is connected to the first terminal of the storage capacitor, the first channel terminal of the third switching TFT, and the second channel terminal of the fifth switching TFT; the first channel terminal of the first driving TFT is connected to the second channel terminal.
  • the first channel end of the TFT is connected to the data line, the second channel end of the first switch TFT is connected to the second end of the storage capacitor and the second channel end of the fourth switch TFT;
  • the control end of the second switch TFT is connected to the first light-emitting control signal,
  • the first path end of the second switch TFT is connected to the first power supply;
  • the control end of the third switch TFT is connected to the second scan control signal;
  • the control end of the fourth switch TFT is connected to the first light emitting control signal, and the first path of the fourth switch TFT
  • the terminal is connected to the reference voltage; the control terminal of the fifth switch TFT is connected to the first scan control signal, and the first path terminal of the fifth switch TFT is connected
  • the compensation circuit in the pixel of the present application compensates for the threshold voltage difference and drift of the driving TFT, avoids the uneven light emission caused by the uneven threshold voltage and the display life problem caused by the threshold voltage drift, and improves the display image quality and life.
  • the compensation circuit in the pixel of the present application simultaneously compensates for the fluctuation of the light-emitting power supply ELVSS, avoids the problems of the difference of the light-emitting power source and uneven light-emitting caused by the voltage drop, and improves the display image quality.
  • the compensation circuit in the pixel of the present application also compensates for the threshold voltage Voled of the light-emitting element, and its driving current is only related to the data voltage Vdata, which avoids the brightness reduction caused by the aging of the light-emitting device and improves the life of the display device.
  • the present application provides a self-luminous display device, including: a first power supply and a second power supply, criss-crossed scan lines and data lines, pixel units defined by the intersection of the scan lines and the data lines, and The pixel electrode in the pixel unit; wherein the scan line provides a first scan signal and a second scan control signal, and the data line provides a data voltage;
  • the self-luminous display device further includes: a compensation circuit in the pixel, the compensation circuit in the pixel is connected to a light-emitting element, the light-emitting element is located between the first power source and the second power source, the light-emitting element is controlled by the first light-emitting control signal and the second power source.
  • Two light-emitting control signal control, the compensation circuit in the pixel includes:
  • a first driving TFT connected to the light-emitting element, a first switching TFT located at the intersection of the scan line and the data line, a second switching TFT, a third switching TFT connected to the first light-emitting control signal, A fourth switching TFT connected to the second light emission control signal, a fifth switching TFT connected to the first driving TFT, and a storage capacitor;
  • the access point of the pixel unit is located at the intersection of the first switch TFT, the fourth switch TFT and the storage capacitor;
  • the fifth switch TFT is connected to the first scan control signal, and the first switch TFT and the third switch TFT are respectively connected to the second scan control signal;
  • the control terminal of the first driving TFT is sequentially charged and the data voltage is input to the connection of the pixel unit in the consecutive first time period, second time period, third time period, and fourth time period.
  • the input point and the threshold voltage of the control terminal of the first driving TFT are extracted, the voltages of the access point of the pixel unit and the control terminal of the first driving TFT are locked, and the voltage difference across the storage capacitor is also locked at the same time ,
  • the light-emitting element enters the light-emitting stage.
  • control terminal of the first driving TFT is connected to the first terminal of the storage capacitor, the first channel terminal of the third switching TFT and the second channel terminal of the fifth switching TFT;
  • the first path end of a driving TFT is connected to the second path end of the second switching TFT and the second path end of the third switching TFT;
  • the second path end of the first driving TFT is connected to the light emitting element positive electrode.
  • control terminal of the first switch TFT is connected to the second scan control signal
  • first channel terminal of the first switch TFT is connected to the data line
  • second channel terminal of the first switch TFT is connected to the data line.
  • the second terminal of the storage capacitor is connected to the second channel terminal of the fourth switch TFT.
  • control terminal of the second switching TFT is connected to the first light-emitting control signal, the first path terminal of the second switching TFT is connected to the first power supply; the control terminal of the third switching TFT is connected to The second scan control signal; the control terminal of the fourth switch TFT is connected to the second light-emitting control signal, the first path terminal of the fourth switch TFT is connected to a reference voltage; the control terminal of the fifth switch TFT The first scan control signal is connected, and the first path end of the fifth switch TFT is connected to the first power supply or the reference voltage.
  • the first scan control signal and the second light-emitting control signal are input high, and the second scan control signal and the first light-emitting control signal are input low.
  • the fourth switching TFT and the fifth switching TFT are turned on, the second switching TFT and the third switching TFT are turned off, the light-emitting element stops emitting light, and the first driving TFT
  • the control terminal is charged and reset through the fifth switch TFT;
  • the second scan control signal and the data voltage are input to a high level, and the first scan control signal, the first light emission control signal, and the second light emission control signal are input Low level; at this time, the fifth switching TFT, the second switching TFT, and the fourth switching TFT are off, and the first switching TFT, the third switching TFT, and the first driving TFT are in In the open state, the gate and drain of the first driving TFT are connected together to form a diode connection; the voltage of the control terminal of the first driving TFT is discharged to the light-emitting element through the first driving TFT until When the voltage between the gate and drain of the first driving TFT drops to the threshold voltage, the first driving TFT is turned off and discharging stops; the threshold voltage of the first driving TFT is successfully extracted to the first On the control terminal of a driving TFT and saved by the storage capacitor; at the same time, the data voltage is written into the access point of the pixel unit through the first switching TFT;
  • the first light-emitting control signal is input at a high level, and the second light-emitting control signal, the first scan control signal, the second scan control signal, and the data voltage are input Low level; at this time, the first switch TFT, the third switch TFT, the fourth switch TFT, and the fifth switch TFT are turned off, and the access point of the pixel unit and the first driver The voltage at the control terminal of the TFT is locked, and the voltage difference across the storage capacitor is also locked at the same time; at the same time, the second switch TFT is turned on and enters the light-emitting preparation stage;
  • the fourth switch TFT is turned on, the voltage of the access point of the pixel unit changes from the data voltage to the reference voltage; the voltage change of the access point of the pixel unit will be coupled to the The control terminal of the first driving TFT, the first driving TFT is turned on, a conductive path is formed between the first power source and the second power source, and current flows through the light-emitting element to emit light.
  • the present application also provides a self-luminous display device, including: a first power source and a second power source, criss-crossed scan lines and data lines, a pixel unit defined by the intersection of the scan line and the data line, and a pixel unit located at the pixel The pixel electrode in the cell; wherein the scan line provides a first scan signal and a second scan control signal, and the data line provides a data voltage;
  • the self-luminous display device further includes: an in-pixel compensation circuit connected to a light-emitting element; the light-emitting element is located between a first power source and a second power source, and the light-emitting element is controlled by a first light emission control signal Control; the compensation circuit within the pixel includes:
  • a first driving TFT connected to the light-emitting element, a first switching TFT located at the intersection of the scan line and the data line, a second switching TFT, a third switching TFT connected to the first light-emitting control signal, A fourth switching TFT connected to the first light emitting control signal, a fifth switching TFT connected to the first driving TFT, and a storage capacitor;
  • the access point of the pixel unit is located at the intersection of the first switch TFT, the fourth switch TFT and the storage capacitor;
  • the scan line provides a first scan control signal and a second scan control signal
  • the fifth switch TFT is connected to the first scan control signal
  • the first switch TFT and the third switch TFT are connected to the The second scan control signal connection
  • the control terminal of the first driving TFT is sequentially charged and the data voltage is input to the access point of the pixel unit in the consecutive first time period, second time period, third time period, and fourth time period. And extracting the threshold voltage of the control terminal of the first driving TFT, the voltages of the access point of the pixel unit and the control terminal of the first driving TFT are locked, and the voltage difference across the storage capacitor is also locked at the same time, so The light-emitting element enters the light-emitting stage.
  • control terminal of the first driving TFT is connected to the first terminal of the storage capacitor, the first channel terminal of the third switching TFT and the second channel terminal of the fifth switching TFT;
  • the first path end of a driving TFT is connected to the second path end of the second switching TFT and the second path end of the third switching TFT;
  • the second path end of the first driving TFT is connected to the light emitting element positive electrode;
  • the control terminal of the first switch TFT is connected to the second scan control signal, the first channel terminal of the first switch TFT is connected to a data line, and the second channel terminal of the first switch TFT is connected to the storage capacitor.
  • the control terminal of the second switching TFT is connected to the first light-emitting control signal, the first path terminal of the second switching TFT is connected to the first power supply; the control terminal of the third switching TFT is connected to the second Scanning control signal; the control terminal of the fourth switch TFT is connected to the first light-emitting control signal, the first path terminal of the fourth switch TFT is connected to a reference voltage; the control terminal of the fifth switch TFT is connected to the first A scan control signal, the first path end of the fifth switch TFT is connected to the first power source or the reference voltage.
  • Figure 1 is a conventional uncompensated pixel circuit
  • FIG. 2 is a schematic structural diagram of a first embodiment of a compensation circuit in a pixel according to the present application
  • FIG. 3 is a waveform diagram of driving signals of the compensation circuit in the pixel shown in FIG. 2;
  • FIG. 4 is a schematic structural diagram of the driving signal waveform diagram shown in FIG. 3 in the first time period
  • FIG. 5 is a schematic structural diagram of the driving signal waveform diagram shown in FIG. 3 in a second time period
  • FIG. 6 is a schematic structural diagram of the driving signal waveform diagram shown in FIG. 3 in the third time period
  • FIG. 7 is a schematic structural diagram of the driving signal waveform diagram shown in FIG. 3 in the fourth time period;
  • FIG. 8 is a schematic structural diagram of a second embodiment of a compensation circuit in a pixel according to the present application.
  • FIG. 9 is a waveform diagram of a driving signal of the compensation circuit in the pixel shown in FIG. 8;
  • FIG. 10 is a schematic structural diagram of a third embodiment of a compensation circuit within a pixel of this application.
  • FIG. 11 is a waveform diagram of the driving signal of the compensation circuit in the pixel shown in FIG. 10;
  • FIG. 12 is a schematic diagram of circuit simulation results of the compensation circuit in the pixel shown in FIG. 2 and FIG. 8 at different data voltages Vdata;
  • FIG. 13 is a schematic diagram of circuit simulation results of the compensation circuit in the pixel shown in FIG. 2 and FIG. 8 at different threshold voltages Vth.
  • FIG. 2 is a schematic structural diagram of the first embodiment of the compensation circuit in the pixel of the present application, which is used to compensate for the self-luminous display device.
  • the compensation circuit in the pixel is connected to the light-emitting element 30, and the light-emitting element 30 is located in the first power supply (the first Between a positive power supply, the voltage of which is ELVDD, and a second power supply (the second power is a negative power, the voltage of ELVSS), the light-emitting element 30 is controlled by the first light-emitting control signal EM1 and the second light-emitting control signal EM2 .
  • the self-luminous display device includes crisscrossed scan lines and data lines, pixel units defined by the intersection of the scan lines and data lines, and pixel electrodes located in the pixel units; wherein the scan lines provide a first scan signal Scan1 and a second scan control signal Scan2 ,
  • the data line provides the data voltage Vdata.
  • the compensation circuit in the pixel is connected to the pixel unit and includes a first driving TFT 11 connected to the light-emitting element 30, a first switching TFT 12, a second switching TFT 13, a third switching TFT 14, and a first switching TFT located at the intersection of the scan line and the data line.
  • the first driving TFT 11 is a driving TFT switch; the access point of the pixel unit (referred to as PIX point) is located at the first switching TFT 12 and the fourth switching TFT The intersection of 15 and the storage capacitor Cst; the storage capacitor Cst has both the functions of a coupling capacitor and a storage capacitor, which reduces the number of components of the compensation circuit in the pixel, and provides the possibility for a self-luminous display device with a higher PPI .
  • each TFT switch involved in the following embodiments includes a control terminal, a first channel terminal, and a second channel terminal.
  • the control terminal is a gate
  • one channel terminal is a source and the other channel terminal is a drain. pole.
  • the first driving TFT 11 is located between the light-emitting element 30 and the first power source, and is connected to the light-emitting element 30 in series.
  • the control terminal of the first driving TFT 11 is point G, and point G is connected to the first terminal of the storage capacitor Cst, the first channel terminal of the third switching TFT 14 and the second channel terminal of the fifth switching TFT 16;
  • the first path end of the driving TFT 11 is point D, and point D connects the second path end of the second switching TFT 13 and the second path end of the third switching TFT 14;
  • the second path end of the first driving TFT 11 is point S, The point S is connected to the anode of the light-emitting element 30.
  • the control terminal of the first switch TFT 12 is connected to the second scan control signal Scan2, the first channel terminal of the first switch TFT 12 is connected to the data line, and the second channel terminal of the first switch TFT 12 is connected to the second terminal of the storage capacitor Cst and the fourth switch TFT 15 second channel end.
  • the second switching TFT 13 is located between the first driving TFT 11 and the first power source. Specifically, the control terminal of the second switching TFT 13 is connected to the first light emission control signal EM1, and the first channel terminal of the second switching TFT 13 is connected to the first power source The second path end of the second switching TFT 13 is connected to the first path end of the first driving TFT 11 and the second path end of the third switching TFT 14. In fact, the second switching TFT 13, the first driving TFT 11, and the light emitting element 30 are connected in series between the first power source and the second power source.
  • the control terminal of the third switching TFT 14 is connected to the second scanning control signal Scan2, and the first path terminal of the third switching TFT 14 is connected to the control terminal of the first driving TFT 11, the first terminal of the storage capacitor Cst, and the fifth switching TFT 16
  • the second path end of the third switching TFT 14 is connected to the first path end of the first driving TFT 11 and the second path end of the second switching TFT 13.
  • the control terminal of the fourth switch TFT 15 is connected to the second light-emitting control signal EM2, the first channel terminal of the fourth switch TFT 15 is connected to the reference voltage Vref, and the second channel terminal of the fourth switch TFT 15 is connected to the second terminal of the storage capacitor Cst and
  • the second path end of the first switching TFT 12, that is, the second path end of the first switching TFT 12, the second end of the storage capacitor Cst, and the second path end of the fourth switching TFT 15 also converge at the PIX point.
  • the control end of the fifth switch TFT 16 is connected to the first scan control signal Scan1, the first path end of the fifth switch TFT 16 is connected to the first power supply or reference voltage Vref, and the second path end of the fifth switch TFT 16 is connected to the third switch TFT The first path end of 14, the control end of the first driving TFT 11, and the first end of the storage capacitor Cst.
  • the control terminal of the first driving TFT 11, the first terminal of the storage capacitor Cst, the first channel terminal of the third switching TFT 14 and the second channel terminal of the fifth switching TFT 16 meet at point G;
  • the first terminal of the first driving TFT 11 A path end, the second path end of the third switching TFT 14 and the first path end of the second switching TFT 13 intersect at point D;
  • the second path end of the first driving TFT 11 and the anode of the light-emitting element 30 intersect at point S .
  • the driving signal waveform diagram of the first embodiment of the compensation circuit in the pixel of the present application in which, in the continuous first time period (specifically the period T1), the second time period (specifically the period T2), and the first During the three time periods (specifically, the T3 period) and the fourth time period (specifically, the T4 period), the control terminal G of the first driving TFT 11 is sequentially charged, the data voltage Vdata is input to the PIX point, and the first driving TFT 11 is controlled The threshold voltage Vth of the terminal G point is extracted, the voltages of the PIX point and the control terminal G of the first driving TFT 11 are locked, the voltage difference across the storage capacitor Cst is also locked, and the light-emitting element 30 enters the light-emitting stage.
  • the first scan control signal Scan1 and the second light emission control signal EM2 are input to a high level, and the second scan control signal Scan2 and the first light emission control signal The signal EM1 is input low.
  • the fifth switching TFT 16 is turned on, the first switching TFT 12, the second switching TFT 13, and the third switching TFT 14 are turned off, the light emitting element 30 stops emitting light, and the control terminal G point of the first driving TFT 11 passes through the fifth switching TFT. 16Charge reset.
  • the second scan control signal Scan2 and the data voltage Vdata are input to a high level, and the first scan control signal Scan1, the first light emission control signal EM1, and the second light emission
  • the control signal EM2 is input low.
  • the fifth switching TFT 16, the second switching TFT 13, and the fourth switching TFT 15 are turned off, the first switching TFT 12 and the third switching TFT 14 are turned on, the first driving TFT 11 is in the on state, and the first driving TFT 11 is turned on.
  • the gate and drain are connected together to form a diode connection.
  • the voltage at the control terminal G of the first driving TFT 11 is discharged to the light emitting element 30 through the first driving TFT 11 until the gate and drain of the first driving TFT 11 When the voltage Vgs between the electrodes drops to the threshold voltage Vth, the first driving TFT 11 is turned off, and the discharge stops. At this time, the voltage at the point G of the control terminal of the first driving TFT 11 is (ELVSS+Voled+Vth). So far, the threshold voltage Vth of the first driving TFT 11 is successfully extracted to the control terminal G point of the first driving TFT 11, and is stored by the storage capacitor Cst. At the same time, the data voltage Vdata is written into the PIX point through the first switching TFT 12.
  • the first light-emission control signal EM1 is input at a high level
  • the second light-emission control signal EM2 the first scan control signal Scan1, and the second scan control signal Scan2 are input Low level.
  • the first switch TFT 12, the third switch TFT 14, the fourth switch TFT 15, and the fifth switch TFT 16 are turned off, the voltages of the PIX point and the G point are locked, and the voltage difference across the storage capacitor Cst is also locked at the same time.
  • the second switch TFT 13 is turned on and enters the light-emitting preparation stage.
  • the fourth time period (specifically, the period T4)
  • the first light-emission control signal EM1 and the second light-emission control signal EM2 are input at a high level
  • the first scan control signal Scan1 and the second scan control signal Scan2 are input Low level
  • the fourth switch TFT 15 is turned on, and the voltage of the PIX node changes from the data voltage Vdata to the reference voltage Vref.
  • the voltage change of the PIX node will be coupled to point G, so point G
  • the voltage change of is (ELVSS+Voled+Vth+Vref-Vdata)
  • the first driving TFT 11 is turned on, a conductive path is formed between the first power source and the second power source, and current flows through the light-emitting element 30 to emit light.
  • the current flowing through the light-emitting element 30 is controlled by the first driving TFT 11. Since the drain voltage of the first driving TFT 11 is ELVDD, the first driving TFT 11 works in the saturation region, and its working current is 1/2K (Vgs-Vth)2, that is, 1/2K (Vref-Vdata)2.
  • K is a coefficient, which is related to the channel width W, the channel length L, the mobility and the gate capacitance Cox of the TFT.
  • VG ELVSS+Voled+Vth+Vref-Vdata
  • VS ELVSS+Voled
  • the driving current flowing through the light-emitting element 30 is only related to the data voltage Vdata and the reference voltage Vref.
  • the reference voltage Vref is a constant reference voltage, and the driving current is actually controlled only by the data voltage Vdata. Since the threshold voltage Vth of the first driving TFT 11 is extracted in the second time period (specifically during the T2 period), the current in the light-emitting phase is not affected by the threshold voltage Vth of the first driving TFT 11, and the threshold voltage Vth is compensated. effect.
  • the light-emitting brightness is not affected by the deviation of the threshold voltage Vth caused by the uniformity of the process, so that the light-emitting brightness of the display area is more uniform, and better image quality performance is achieved.
  • the threshold voltage Vth is compensated, even if the threshold voltage Vth of the first driving TFT 11 shifts after a long time of operation, its brightness will not be significantly affected, which improves the working life and reliability of the self-luminous display device.
  • FIG. 8 is a schematic diagram of the second embodiment of the compensation circuit in the pixel of the present application.
  • the difference from the first embodiment shown in FIG. 2 is: the first path end (that is, the drain) of the fifth switching TFT 16 and the reference voltage Vref connection.
  • the driving signal waveform diagram of the compensation circuit in the pixel shown in FIG. 8 is the same as that of FIG. 3, and the description will not be repeated here.
  • FIG. 9 is a schematic diagram of the third embodiment of the compensation circuit in the pixel of the present application.
  • the difference between FIG. 9 and the first embodiment shown in FIG. 2 is: the first path end (that is, the drain) of the fifth switching TFT 16 and First power connection.
  • the driving signal waveform diagram of the compensation circuit in the pixel shown in FIG. 9 is the same as that of FIG. 3, and the description of FIG. 9 will not be repeated here.
  • FIG. 10 is a schematic diagram of the fourth embodiment of the compensation circuit in the pixel of the present application.
  • the difference between FIG. 10 and the third embodiment shown in FIG. 9 is: the control terminal (ie, the gate) of the fourth switching transistor M5 and the first The light emission control signal EM1 is connected. That is to say, there is only one first light emission control signal EM1.
  • FIG. 11 is a waveform diagram of the driving signal of the compensation circuit in the pixel shown in FIG. 10.
  • the first time period (specifically, the T1 period)
  • the first scan control signal Scan1 is input to a high level
  • the second scan control signal Scan2 and the first light-emitting
  • the control signal EM1 is input to a low level.
  • the fifth switch TFT 16 is turned on, the first switch TFT 12, the second switch TFT 13, the third switch TFT 14, and the fourth switch TFT 15 are turned off, and the light emitting element 30 stops emitting light.
  • the control terminal G point of the driving TFT 11 is charged and reset through the fifth switch TFT 16.
  • the second scan control signal Scan2 and the data voltage Vdata are input to a high level, and the first scan control signal Scan1 and the first light emission control signal EM1 are input to a low level.
  • the fifth switching TFT 16, the second switching TFT 13, and the fourth switching TFT 15 are turned off, the third switching TFT 14 and the first switching TFT 12 are turned on, and the first driving TFT 11 is in an on state.
  • the gate and drain of the first driving TFT 11 are connected together to form a diode connection.
  • the voltage at the control terminal G of the first driving TFT 11 is discharged to the light emitting element 30 through the first driving TFT 11 until the first When the voltage Vgs between the gate and drain of the driving TFT 11 drops to the threshold voltage Vth, the first driving TFT 11 is turned off and the discharge stops. At this time, the voltage at the point G of the control terminal of the first driving TFT 11 is (ELVSS+Voled+Vth). So far, the threshold voltage Vth of the first driving TFT 11 is successfully extracted to the control terminal G point of the first driving TFT 11, and is stored by the storage capacitor Cst. At the same time, the data voltage Vdata is written into the PIX point through the first switching TFT 12.
  • the first light-emitting control signal EM1 is input to a high level, and the first scan control signal Scan1 and the second scan control signal Scan2 are input to a low level.
  • the first switch TFT 12, the third switch TFT 14, and the fifth switch TFT 16 are turned off, the voltages of the PIX point and the G point are locked, and the voltage difference across the storage capacitor Cst is also locked at the same time.
  • the second switching TFT 13 and the fourth switching TFT 15 are turned on and enter the light-emitting preparation stage.
  • the first light-emitting control signal EM1 is input to a high level
  • the first scan control signal Scan1 and the second scan control signal Scan2 are input to a low level
  • the fourth switch TFT 15 is turned on
  • the PIX node The voltage of is changed from the data voltage Vdata to the reference voltage Vref. Since the voltage difference across the storage capacitor Cst is locked, the voltage change of the PIX node will be coupled to the G point. Therefore, the voltage change of the G point is (ELVSS+Voled+Vth+Vref-Vdata), the first driving TFT 11 is turned on, and the first driving TFT 11 is turned on.
  • a conductive path is formed between the first power source and the second power source, and current flows through the light-emitting element 30 to emit light.
  • FIG. 12 shows the driving current changes under different data voltages Vdata
  • the simulation results show that the data voltage Vdata can normally control the driving current of the pixel circuit.
  • FIG. 13 shows the driving current changes under different threshold voltages Vth when the threshold voltage Vth of the first driving TFT 11 changes. It can be seen from FIG. 13 that within a larger threshold voltage Vth voltage variation range, the driving current of each gray scale maintains relatively good stability without significant current attenuation.
  • the compensation circuit in the pixel of the present application can also compensate for the influence of fluctuations of the second power supply. Since the self-luminous display device is driven by current, both the first power source and the second power source in the self-luminous display device need to provide a relatively large current. When the current flows through the conductive path between the first power supply and the second power supply, a voltage drop IR-drop will be generated. This voltage drop will cause the voltage of the first power supply and the voltage of the second power supply actually obtained by each pixel in the display area Produce differences, resulting in uneven display effects.
  • the driving current of the compensation circuit in the pixel of the present application is only related to the data voltage Vdata, which compensates for the voltage of the first power supply and the voltage of the second power supply, avoids the unevenness of the picture caused by the voltage drop IR-drop, and is beneficial to achieve better Screen display effect.
  • the threshold voltage Voled of the light-emitting element will drift after a long time of operation, resulting in a decrease in display brightness.
  • the compensation circuit in the pixel of the present application can also compensate the threshold voltage Voled of the light-emitting element 30 at the same time.
  • the light-emitting element 30 does not emit light.
  • the maintenance phase of the data voltage Vdata and the threshold voltage Vth compensation phase in the third time period (specifically, the T3 period)
  • the light-emitting element 30 will not emit light. Therefore, the light-emitting element 30 only emits light during the fourth time period (specifically, the T4 period). This avoids the problem that the light-emitting element emits light during the first time period (specifically, the T1 period) to the third time period (specifically, the T3 period), which causes the black screen to be not black enough and the contrast to decrease.
  • the compensation circuit in the pixel of the present application compensates the threshold voltage Voled of the light-emitting element, and its driving current is only related to the data voltage Vdata, which avoids the brightness reduction caused by the aging of the light-emitting device and improves the life of the display device.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
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Abstract

Circuit de compensation intra-pixel et appareil d'affichage luminescent. Le circuit de compensation intra-pixel comprend un premier TFT d'attaque connecté à un élément électroluminescent, un premier TFT de commutation situé à une intersection d'une ligne de balayage et d'une ligne de données, un deuxième TFT de commutation connecté à un premier signal de commande d'émission de lumière, un troisième TFT de commutation, un quatrième TFT de commutation connecté à un second signal de commande d'émission de lumière, un cinquième TFT de commutation connecté au premier TFT d'attaque, et un condensateur de stockage, un point d'accès d'une unité de pixel étant situé à une intersection du premier TFT de commutation, du quatrième TFT de commutation et du condensateur de stockage ; et la ligne de balayage fournit un premier signal de commande de balayage et un second signal de commande de balayage, le cinquième TFT de commutation est connecté au premier signal de commande de balayage, et le premier TFT de commutation et le troisième TFT de commutation sont connectés au second signal de commande de balayage. Le circuit de compensation intra-pixel dans la présente invention compense une tension de seuil Voled d'un élément électroluminescent, et le courant d'attaque de celui-ci est uniquement lié à une tension de données Vdonnées, de telle sorte que la réduction de luminosité d'un dispositif électroluminescent provoquée par le vieillissement est empêchée, et la durée de vie d'un dispositif d'affichage est prolongée.
PCT/CN2020/086610 2019-11-25 2020-04-24 Circuit de compensation intra-pixel et appareil d'affichage luminescent WO2021103408A1 (fr)

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