WO2021103406A1 - 一种自发光显示装置以及像素内补偿电路 - Google Patents

一种自发光显示装置以及像素内补偿电路 Download PDF

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Publication number
WO2021103406A1
WO2021103406A1 PCT/CN2020/086364 CN2020086364W WO2021103406A1 WO 2021103406 A1 WO2021103406 A1 WO 2021103406A1 CN 2020086364 W CN2020086364 W CN 2020086364W WO 2021103406 A1 WO2021103406 A1 WO 2021103406A1
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tft
light
control signal
voltage
switch
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PCT/CN2020/086364
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English (en)
French (fr)
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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 WO2021103406A1 publication Critical patent/WO2021103406A1/zh

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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 invention relates to the technical field of display panels, and in particular to a self-luminous display device and a compensation circuit in a pixel.
  • Self-luminous types include organic electroluminescent OLED, quantum dot electroluminescent QLED, micro-electroluminescent Micro-LED, and self-luminous displays are in These aspects have natural advantages.
  • 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 elements is provided by the TFT backplane, including LTPSTFT and oxide semiconductor TFT.
  • the characteristics of the TFT including the threshold voltage Vth and the mobility
  • Vth and the mobility are prone to deviation or drift, resulting in deviation or drift of the driving current, which affects the uniformity and lifetime of the display. Therefore, a pixel circuit for self-luminous display is usually equipped with a circuit to compensate for the deviation or drift of TFT characteristics to improve display uniformity and lifetime problems.
  • the pixel compensation circuit usually has a current control mode and a voltage control mode.
  • the current control mode can compensate the threshold voltage and mobility of the TFT at the same time; the voltage control mode generally can only compensate the threshold voltage of the TFT.
  • the current control mode has the following two problems: (1) The control current is weak current, which requires high design requirements for the driver IC; (2) Due to the influence of parasitic capacitance, the pixel compensation circuit of the current control mode requires a relatively long setting. Time can achieve the compensation effect. Therefore, the current pixel compensation circuit mostly adopts a voltage control mode.
  • Figure 1 shows an existing uncompensated pixel driving circuit, which includes a switching TFT 1, a driving TFT 2, and a storage capacitor 3.
  • the switching TFT 1 is controlled by the scan signal Scan to input the data signal Vdata to the gate path end of the driving TFT 2,
  • the driving TFT 2 is controlled by the voltage at the gate path end under the action of the power supply ELVDD to output a driving current, and the current flows through the light-emitting element 4 to emit light.
  • the storage capacitor 3 is connected to the gate path end of the driving TFT 2 and the power source ELVDD, and is used to maintain the voltage of the gate path end of the driving TFT 2 to prevent it from changing due to leakage during a refresh period.
  • the uncompensated pixel compensation circuit does not compensate for the characteristics of the TFT, and the current flowing through the light-emitting element will be changed by the characteristic deviation and drift of the driving TFT, resulting in display uniformity and lifetime problems.
  • 110TFT is the driving TFT, which provides current to the light-emitting element, and the current is controlled by its gate voltage
  • 111TFT is the switching TFT for data voltage input, which is used to switch and control the input of data voltage
  • 112TFT is another switching TFT, which is used For switching control on the input of the reference voltage
  • 113TFT is another switching TFT, used to control the gate and drain of the driving TFT to be short-circuited, so that the 110TFT forms a diode connection, which is used to extract the threshold voltage Vth of the 110TFT
  • 114TFT It is another switching TFT, used to switch the light emission of the light-emitting element, and cooperate with the 113TFT to perform the Vth extraction operation.
  • the pixel compensation circuit can charge the gate of 110TFT at time t0 ⁇ t1 through the cooperation of 113TFT and 114TFT, and extract the threshold voltage Vth of 110TFT through 110TFT discharge at time t1 ⁇ t2.
  • the data voltage is input to point A, and the data voltage is coupled to the gate of 110 TFT through the coupling of the 121 capacitor. In this way, the Vth compensation process of 110TFT is realized.
  • the pixel compensation circuit requires two capacitors at the same time, of which the 121 capacitor is used to couple the data voltage, and the 122 capacitor is used to store the pixel voltage to prevent leakage.
  • the size of the two capacitors needs to be designed to a sufficient size, and in a design with a higher pixel density, the capacitor will occupy a larger layout space, which limits the increase in pixel density.
  • the object of the present invention is to provide a self-luminous display device and an in-pixel compensation circuit that reduce the number of components of the compensation circuit in the pixel and increase the working life.
  • the present invention 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;
  • it includes a first driving TFT connected to the light-emitting element, a first switching TFT located at the intersection of a scan line and a data line, a storage capacitor located between the first driving TFT and the first switching TFT, a second The switching TFT, the third switching TFT, the fourth switching TFT and the access point; wherein the access point is located between the first switching TFT and the storage capacitor; the second switching TFT is connected to the first power supply, the second light emitting control signal and the first Between a driving TFT; the third switch TFT is connected with the scan control signal provided by the scan line; the fourth switch TFT is connected with the reference voltage and the first light-emitting control signal;
  • the storage capacitor is a capacitor with both coupling and storage functions.
  • the path end of the first driving TFT is connected to the first end of the storage capacitor, the first path end of the first driving TFT is connected to the first path end of the second switching TFT, and the second path end of the first driving TFT is connected to The anode of the light-emitting element;
  • the path end of the first switch TFT is connected to the scan line, the first path end of the first switch TFT is connected to the data line, and the second path end of the first switch TFT is connected to the second end of the storage capacitor;
  • the second switch TFT The path end of the second switch TFT is connected to the second light-emitting control signal, the second path end of the second switch TFT is connected to the first power supply;
  • the path end of the third switch TFT is connected to the scan control signal provided by the scan line, and the first path end of the third switch TFT Connect the first channel end of the second switching TFT, the second channel end of the third switching TFT is connected to the channel end of the first driving TFT; the channel end of the fourth switching TFT
  • the second path end of the first switching TFT, the second end of the storage capacitor, and the second path end of the fourth switching TFT also intersect at the access point; wherein, the pixel unit is precharged in the first time period In the third time period, the input voltage of the access point is maintained as the reference voltage.
  • the scan signal of the scan line is input high level
  • the first light emission control signal is input low level
  • the first switch TFT is turned on
  • the fifth switch transistor is turned off
  • the data voltage is input to the access point
  • third The switching TFT and the second switching TFT are also in an open state, the first power source is input to the channel end of the first driving TFT, and the access point is precharged.
  • the second light-emitting control signal is input to a low level, the second switch TFT is turned off; the first driving TFT is in the on state, the path end of the first driving TFT is connected to the first path end, and the first driving The TFT forms a diode connection; the charge at the path end of the first driving TFT is discharged to the light-emitting element through the first driving TFT until the voltage between the gate and source of the first driving TFT drops to a threshold voltage, the first driving TFT is turned off , The discharge stops.
  • the scan signal and scan control signal of the scan line are input at low level
  • the first light emission control signal is input at high level
  • the third switch TFT is turned off, and the charge at the channel end of the first driving TFT is locked
  • the voltage difference between the two ends of the storage capacitor is also locked; the voltage of the access point changes from the data voltage to the participating voltage, and the voltage change of the access point is coupled to the path end of the first driving TFT.
  • the second light-emitting control signal is input with a high level, the second switch 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 invention also provides a self-luminous display device, which includes an N-level gate drive circuit, an N-level output light-emission control circuit, and an in-pixel compensation circuit that is connected to the gate drive circuit and the light-emission control circuit.
  • the scan signal is connected to the output terminal of the n-th stage gate drive circuit
  • the first light-emitting control signal is connected to the n-th stage output terminal of the light-emitting control circuit
  • the second light-emitting control signal is connected to the n+1 stage output terminal of the light-emitting control circuit , Where n ⁇ N.
  • the pixel compensation circuit 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 storage capacitor located between the first driving TFT and the first switching TFT, the second switching TFT, and the third switch TFT, a fourth switching TFT and an access point; wherein, the access point is located between the first switching TFT and the storage capacitor; the second switching TFT is connected between the first power supply, the second light emitting control signal and the first driving TFT;
  • the third switch TFT is connected to the scan control signal provided by the scan line; the fourth switch TFT is connected to the reference voltage and the first light-emitting control signal; wherein the first time period, the second time period, the third time period, and
  • the first driving TFT is charged sequentially, the input data voltage and the threshold voltage of the first driving TFT are extracted, the threshold voltage of the first driving TFT is compensated, and the light-emitting element enters the light-emitting stage.
  • the storage capacitor is a capacitor with both coupling and storage functions.
  • the path end of the first driving TFT is connected to the first end of the storage capacitor, the first path end of the first driving TFT is connected to the first path end of the second switching TFT, and the second path end of the first driving TFT is connected to The anode of the light-emitting element;
  • the path end of the first switch TFT is connected to the scan line, the first path end of the first switch TFT is connected to the data line, and the second path end of the first switch TFT is connected to the second end of the storage capacitor;
  • the second switch TFT The path end of the second switch TFT is connected to the second light-emitting control signal, the second path end of the second switch TFT is connected to the first power supply;
  • the path end of the third switch TFT is connected to the scan control signal provided by the scan line, and the first path end of the third switch TFT Connect the first channel end of the second switching TFT, the second channel end of the third switching TFT is connected to the channel end of the first driving TFT; the channel end of the fourth switching TFT
  • the second path end of the first switching TFT, the second end of the storage capacitor, and the second path end of the fourth switching TFT also intersect at the access point; wherein, the access point is connected to the access point during the first time period. Perform pre-charging, and the input voltage of the access point is maintained at the reference voltage during the third time period.
  • the scan signal of the scan line is input high level
  • the first light emission control signal is input low level
  • the first switch TFT is turned on
  • the fifth switch transistor is turned off
  • the data voltage is input to the access point
  • third The switching TFT and the second switching TFT are also in an open state, the first power source is input to the channel end of the first driving TFT, and the access point is precharged.
  • the second light-emitting control signal is input to a low level, the second switch TFT is turned off; the first driving TFT is in the on state, the path end of the first driving TFT is connected to the first path end, and the first driving The TFT forms a diode connection; the charge at the path end of the first driving TFT is discharged to the light-emitting element through the first driving TFT until the voltage between the gate and source of the first driving TFT drops to a threshold voltage, the first driving TFT is turned off , The discharge stops.
  • the scan signal and scan control signal of the scan line are input at low level
  • the first light emission control signal is input at high level
  • the third switch TFT is turned off, and the charge at the channel end of the first driving TFT is locked
  • the voltage difference between the two ends of the storage capacitor is also locked; the voltage of the access point changes from the data voltage to the participating voltage, and the voltage change of the access point is coupled to the path end of the first driving TFT.
  • the second light-emitting control signal is input with a high level, the second switch 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 application also provides a display device including the self-luminous display device described above.
  • the display device can be any of the following: mobile phones, tablets, laptops, monitors, and TV products.
  • the present invention extracts the threshold voltage Vth of the first switching TFT through the first driving TFT using a diode connection, and compensates the driving voltage of the first driving TFT through capacitive coupling, and offsets the effect of Vth unevenness and Vth drift on the display effect. Adverse effects; the present invention reduces the number of components of the compensation circuit in the pixel; and improves the working life of the self-luminous display device.
  • Figure 1 shows an existing uncompensated pixel drive circuit
  • Figure 2 shows an existing voltage-controlled pixel compensation circuit
  • FIG. 3 is a schematic diagram of the structure of the compensation circuit in the pixel of the present invention.
  • FIG. 4 is a waveform diagram of the driving signal of the compensation circuit in the pixel of the present invention.
  • FIG. 5 is a schematic structural diagram of the driving signal waveform diagram shown in FIG. 4 in the first time period
  • FIG. 6 is a schematic structural diagram of the driving signal waveform diagram shown in FIG. 4 in a second time period
  • FIG. 7 is a schematic structural diagram of the driving signal waveform diagram shown in FIG. 4 in the third time period
  • FIG. 8 is a schematic structural diagram of the driving signal waveform diagram shown in FIG. 4 in the fourth time period
  • FIG. 9 is a schematic diagram of the structure of the self-luminous display device of the present invention.
  • FIG. 10 is a waveform diagram of driving signals of the self-luminous display device shown in FIG. 9;
  • FIG. 11 is a schematic diagram of the structure of the circuit simulation under different data voltages according to the present invention.
  • FIG. 12 is a schematic structural diagram of the circuit simulation performed when the Vth developed by the first TFT changes in the present invention.
  • FIG. 3 is a schematic diagram of the structure of the compensation circuit in the pixel of the present invention, which is used to compensate the self-luminous display device.
  • the compensation circuit in the pixel is connected to the light-emitting element 30, wherein the light-emitting element 30 is located at the first power source ELVDD and the second power source ELVSS Meanwhile, the light-emitting element 30 is controlled by the first light-emission control signal EM1 and the second light-emission control signal EM2.
  • the first power source ELVDD is the positive terminal of the power source
  • the second power source ELVSS is the negative terminal of the power source
  • 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 units located in the pixel units; wherein the scan lines provide scan signals Scan and scan control signals Scan, and the data lines provide Data voltage Vdata.
  • the compensation circuit in the pixel 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, a fourth switching TFT 15, a storage capacitor 20 and the intersection of the scanning line and the data line.
  • Access point (referred to as PIX point for short), where the first driving TFT 11 is a driving TFT switch; the access point (referred to as PIX point for short) is located at the intersection of the first switching TFT 12, the fourth switching TFT 15 and the storage capacitor 20;
  • the storage capacitor 20 has both coupling and storage functions, reducing the number of components of the compensation circuit in the pixel, and providing the possibility for a self-luminous display device with a higher PPI.
  • each TFT switch involved in the following embodiments includes a path end, a first path end, and a second path end.
  • the path end is a gate
  • one of the path ends is a source and the other is a drain. pole.
  • the first driving TFT 11 is located between the light-emitting element 30 and the first power source ELVDD, and is connected to the light-emitting element 30 in series. Specifically, the path end of the first driving TFT 11 is connected to the first end of the storage capacitor 20, the first path end of the first driving TFT 11 is connected to the first path end of the second switching TFT 13, and the second path end of the first driving TFT 11 is connected to light emitting.
  • the positive electrode of element 30 is located between the light-emitting element 30 and the first power source ELVDD, and is connected to the light-emitting element 30 in series. Specifically, the path end of the first driving TFT 11 is connected to the first end of the storage capacitor 20, the first path end of the first driving TFT 11 is connected to the first path end of the second switching TFT 13, and the second path end of the first driving TFT 11 is connected to light emitting.
  • the positive electrode of element 30 is provided to the first driving TFT 11 and the first power source ELVDD, and is connected to the light-e
  • the path end of the first switch TFT 12 is connected to the scan line, the first path end of the first switch TFT 12 is connected to the data line, and the second path end of the first switch TFT 12 is connected to the second end of the storage capacitor 20.
  • the second switching TFT 13 is located between the first driving TFT 11 and the first power source ELVDD. Specifically, the channel end of the second switching TFT 13 is connected to the second light emission control signal EM2, and the second channel end of the second switching TFT 13 is connected to the first power source ELVDD, The first path end of the second switching TFT 13 is connected to the first path end of the first driving TFT 11. 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 ELVDD and the second power source ELVSS.
  • the path end of the third switch TFT 14 is connected to the scan control signal Scan provided by the scan line
  • the first path end of the third switch TFT 14 is connected to the first path end of the second switch TFT 13
  • the second path end of the third switch TFT 14 is connected to the first path.
  • the path end of the driving TFT 11, that is, the first path end of the first driving TFT 11, the first path end of the third switching TFT 14 and the first path end of the second switching TFT 13 intersect at one point.
  • the path end of the fourth switch TFT15 is connected to the first light emission control signal EM1, the first path end of the fourth switch TFT15 is connected to the reference voltage Vref, and the second path end of the fourth switch TFT15 is connected to the second end of the storage capacitor 20, namely the first The second path end of the switching TFT 12, the second end of the storage capacitor 20, and the second path end of the fourth switching TFT 15 also intersect at the PIX point.
  • the path end of the first driving TFT 11 is point G, the first end of the storage capacitor 20 and the second path end of the third switching TFT 14 also intersect at point G;
  • the first path end of the first driving TFT 11 is point A,
  • the first path end of a driving TFT 11, the first path end of the third switching TFT 14 and the first path end of the second switching TFT 13 intersect at point A;
  • the second path end of the first driving TFT 11 is point B, and the first driving TFT 11
  • the second path end of the light-emitting element 30 and the anode of the light-emitting element 30 meet at point B.
  • Fig. 4 is a waveform diagram of the driving signal of the compensation circuit in the pixel of the present invention, in which the first time period (specifically during the T1 period), the second time period (specifically during the T2 period), and the third time period ( During the T3 period) and the fourth period (specifically the T4 period), the PIX point is sequentially precharged and the channel terminal G point of the first driving TFT11 is charged, the data voltage Vdata is input, and the first driving TFT11 is charged.
  • the threshold voltage Vth at the channel end G point is extracted, the PIX point is input and maintained as the reference voltage Vref, and the threshold voltage Vth at the channel end G point of the first driving TFT 11 is compensated, and the light-emitting element 30 enters the light-emitting phase.
  • the PIX point (that is, the access point) is precharged during the first time period (specifically during the T1 period), and the G point of the first driving TFT 11 is charged; during the second time period (specifically during the T2 period)
  • the data voltage Vdata is input through the data line, and the channel terminal G of the first driving TFT 11 extracts Vth;
  • the PIX point ie, the access point
  • the third time period (specifically during the T3 period) inputs the maintenance reference voltage Vref, and the first driving
  • the Vth of the G point of the channel end of the TFT11 is compensated;
  • the fourth period (specifically, the T4 period) is when the light-emitting element 30 enters the light-emitting stage; the time lengths of T1, T2 and T3 are the same, and T4 is not less than the time of T1, T2 and T3. with.
  • the scan signal Scan and the scan control signal Scan of the scan line are high during T1 and T2, they are low during T3 and T4; the first light emission control signal EM1 is low during T1 and T2, It is high during T3 and T4; the second light emission control signal EM2 is high during T1 and T4, and it is low during T2 and T3; data voltage Vdata is high during T2 , During T1, T3 and T4, it is low level.
  • the scan signal Scan of the scan line is input at a high level, and the first light emission control signal EM1 is input at a low level.
  • the first switch TFT12 is turned on, the fifth switch transistor 15 is turned off, and the data voltage Vdata is input to the PIX point;
  • the third switch TFT 14 and the second switch TFT 13 are also in an open state, and the channel terminal G point of the first driving TFT 11 is equivalent to directly inputting the first power ELVDD, and the PIX point is precharged.
  • the second light-emitting control signal EM2 is input to a low level, and the second switching TFT13 is closed at this time; the first driving TFT11 is in an open state, and the path end of the first driving TFT11 is connected to the first path end , The first driving TFT11 forms a diode connection, and the charge at point G of the channel end of the first driving TFT11 is discharged to the light-emitting element 30 through the first driving TFT11 until the Vgs (between the gate and the source) of the first driving TFT11 When the voltage drops to Vth, the first driving TFT 11 is turned off, and the discharge stops.
  • the voltage at point G of the path end of the first driving TFT 11 is (ELVSS+Voled+Vth), and Voled is the voltage of the light-emitting element 30; so far, the first driving TFT 11
  • the Vth of the channel end G of the first driving TFT 11 is successfully extracted to the channel end G of the first driving TFT 11, and is stored by the capacitor Cst of the storage capacitor 20.
  • the scan signal Scan and the scan control signal Scan of the scan line are input low level, and the first light emission control signal EM1 is input high level.
  • the third switch TFT14 is turned off, and the first driving TFT11
  • the charge at point G at the end of the path is locked, and the voltage difference across the capacitor Cst of the storage capacitor 20 is also locked; at the same time, the voltage at the PIX point changes from Vdata to Vref, because the voltage difference between the two ends of the capacitor Cst of the storage capacitor 20 is blocked.
  • the voltage change of the PIX point will be coupled to the path end G point of the first driving TFT 11, so the voltage change of the path end G of the first driving TFT 11 is (ELVSS+Voled+Vth+Vref-Vdata).
  • the second light-emitting control signal EM2 is input to a high level, the second switch TFT13 is turned on, a conductive path is formed between the first power source ELVDD and the second power source ELVSS, and current flows through the light-emitting element 30 to emit light. , Which enters the light-emitting stage.
  • the current flowing through the light-emitting element 30 is controlled by the first driving TFT 11. Since the first path terminal 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. Through this current formula, it can be found that the driving current flowing through the light-emitting element 30 is only related to the Vdata voltage and the Vref voltage. Vref is a constant reference voltage, and the driving current is actually only controlled by the Vdata voltage. Since the Vth of the first driving TFT 11 is extracted during T2, the current in the light-emitting phase is not affected by the Vth of the first driving TFT 11, and the Vth compensation effect is realized.
  • the luminous brightness is not affected by the Vth deviation caused by the uniformity of the process, so that the luminous brightness of the display area is more uniform, and a better picture quality performance is achieved.
  • the Vth since the Vth is compensated, even if the Vth of the first driving TFT 11 drifts 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.
  • the present invention also discloses a self-luminous display device, which includes an N-level gate drive circuit, an N-level output light-emitting control circuit, and an in-pixel compensation circuit connected to the gate drive circuit and the light-emitting control circuit.
  • the scanning signal of the scanning line Scan is connected to the output terminal Gn of the n-th stage gate drive circuit, and the first light-emitting control signal EM1 is connected to the n-th stage of the light-emitting control circuit.
  • the output terminal EMn, the second light emission control signal EM2 is connected to the n+1th stage output terminal EMn+1 of the light emission control circuit, where n ⁇ N.
  • the timing of the signals is the same.
  • the timing of the n-th output terminal EMn of the light-emitting control circuit is the same as the timing of the first light-emitting control signal EM1
  • the timing of the n+1-th output terminal EMn+1 of the light-emitting control circuit is the same as that of the second light-emitting control signal.
  • the timing of EM2 is the same.
  • Figures 11 and 12 are schematic diagrams of the circuit simulation results of the self-luminous display device. After using the pixel compensation circuit of the present invention, Figure 11 shows the driving current changes under different Vdata voltages. The simulation results show that the Vdata voltage can normally control the pixel circuit. Drive current. Figure 12 shows that when the Vth of the first driving TFT changes, the driving current changes under different Vths. It can be seen that the driving current of each gray level maintains a relatively good stability within a larger Vth voltage variation range. , Without significant current attenuation.
  • the compensation circuit in the pixel of the present invention can also compensate for the influence of fluctuations of the first power supply ELVDD. Since the self-luminous display device is driven by current, both the first power source ELVDD and the second power source ELVSS need to provide a relatively large current. When the current flows through the conductive path, a voltage drop IR-drop will be generated. This voltage drop will cause a difference between the first power source ELVDD and the second power source ELVSS actually obtained by each pixel in the display area, resulting in uneven display effects.
  • the driving current of the compensation circuit in the pixel of the present invention is only related to the Vdata voltage, which compensates for the first power source ELVDD and the second power source ELVSS, avoids image unevenness caused by IR-drop, and is beneficial to achieve a better image display effect.
  • the compensation circuit in the pixel of the present invention can also compensate the threshold voltage of the light-emitting element.
  • the threshold voltage of the light-emitting element will drift after working for a long time, resulting in a decrease in display brightness; the compensation circuit in the pixel of the present invention compensates the threshold voltage Voled of the light-emitting element, and its driving current is only related to Vdata, which avoids the brightness caused by the aging of the light-emitting device reduce. Improve the life of the display device.
  • the application scope of the compensation circuit in the pixel of the present invention includes but is not limited to organic light emitting diodes, Micro-LEDs, quantum dot LEDs and other self-luminous flat panel displays, and the used semiconductor technologies include but are not limited to a-Si:H, oxide, and LTPS.
  • the present invention extracts the threshold voltage Vth of the first switching TFT through the first driving TFT using a diode connection, and compensates the driving voltage of the first driving TFT through capacitive coupling, and offsets the effect of Vth unevenness and Vth drift on the display effect. Adverse effects; the present invention reduces the number of components of the compensation circuit in the pixel; and improves the working life of the self-luminous display device.
  • the application also provides a display device including the self-luminous display device described above.
  • the display device can be any of the following: mobile phones, tablets, laptops, monitors, and TV products.

Abstract

一种自发光显示装置以及像素内补偿电路，像素内补偿电路包括与发光元件（30）连接的第一驱动TFT（11）、第一开关TFT（12）以及位于第一驱动TFT（11）和第一开关TFT（12）之间的存储电容（20，Cst）；其中接入点（PIX）位于第一开关TFT（12）和存储电容（20，Cst）之间；其中在连续的第一时间段（T1）、第二时间段（T2）、第三时间段（T3）和第四时间段（T4）内依序第一驱动TFT（11）进行充电、输入数据电压（Vdata）和第一驱动TFT（11）的阈值电压（Vth）进行提取、第一驱动TFT（11）的阈值电压（Vth）进行补偿以及发光元件（30）进入发光阶段（T4）；通过第一驱动TFT（11）采用二极管的连接方式来提取第一开关TFT（12）的阈值电压（Vth），并通过电容耦合作用对第一驱动TFT（11）的驱动电压进行补偿，抵消阈值电压（Vth）不均和阈值电压（Vth）漂移对显示效果的不良影响。

Description

一种自发光显示装置以及像素内补偿电路
本申请要求于2019年11月25日提交中国专利局、申请号为201911163302.X、发明名称为“一种自发光显示装置以及像素内补偿电路”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本发明涉及显示面板的技术领域，尤其涉及一种自发光显示装置以及像素内补偿电路。
背景技术
近年来，显示器件不断在向着薄型化、轻型化和柔性化方向发展，自发光型包括有机电致发光OLED、量子点电致发光QLED、微型电致发光Micro-LED，自发光型的显示器在这些方面具有天然的优势。
对于自发光型显示的发光元件，其发光亮度与施加的电压、电流均成正相关关系。发光亮度与电压的关系会受到环境温度、使用时间等因素的影响而发生变化。因此，采用电压驱动发光元件的方式，很难控制自发光显示器的亮度均一性、稳定型。与之相反，发光元件的亮度与其施加的电流大致上成正比例关系，并且不易受其他因素的干扰。因此，自发光显示器通常采用电流驱动型设计。
驱动发光元件的电流由TFT背板提供，包括LTPSTFT、氧化物半导体TFT。但是TFT的特性(包括阈值电压Vth、迁移率mobility)容易产生偏差或漂移，造成驱动电流偏差或漂移，影响显示均一性和寿命。因此自发光显示的像素电路中通常会设置补偿TFT特性偏差或漂移电路，来改善显示均一性和寿命问题。
像素补偿电路通常有电流控制模式和电压控制模式。电流控制模式可以对TFT的阈值电压和迁移率同时进行补偿；电压控制模式一般只能对TFT的阈值电压进行补偿。但是电流控制模式有以下两个问题：(1)控制电流都是微弱电流，对驱动IC的设计要求很高；(2)由于寄生电容影响，电流控制模式的像素补偿电路需要比较长的设定时间，才能达到补偿效果。因此目前像素补偿电路多采用电压控制模式。
图1所示是现有无补偿像素驱动电路，其包括开关TFT 1、驱动TFT 2和存储电容3,开关TFT 1受扫描信号Scan控制将数据信号Vdata输入到驱动TFT 2的栅极通路端，驱动TFT 2受栅极通路端的电压控制在电源ELVDD作用下，输出驱动电流，电流流经发光元件4发光。存储电容3连接驱动TFT 2的栅极通路端和电源ELVDD，用于维持驱动TFT 2的 栅极通路端的电压，防止其在一个刷新周期内因漏电而发生变化。
无补偿像素补偿电路未对TFT的特性进行补偿，流经发光元件的电流会受到驱动TFT的特性偏差和漂移而发生变化，导致显示均一性和寿命问题。
如图2所示是现有一电压控制型像素补偿电路，其包含5颗TFT和2颗电容。其中110TFT为驱动TFT，给发光元件提供电流，电流大小通过其栅极电压来控制；111TFT为数据电压输入的开关TFT，用来对数据电压的输入进行开关控制；112TFT为另一开关TFT，用于对参考电压的输入进行开关控制；113TFT为另一开关TFT，用来控制驱动TFT的栅极和漏极进行短接，以使110TFT形成diode连接方式，用于提取110TFT的阈值电压Vth；114TFT为另一开关TFT，用于开关发光元件的发光，同时配合113TFT进行Vth提取操作。
该像素补偿电路，可以通过113TFT和114TFT的配合，在t0～t1时间给110TFT的栅极充电，而在t1～t2时间通过110TFT的放电，提取出110TFT的阈值电压Vth。在t3～t4时间，将数据电压输入到A点，并通过121电容的耦合，将数据电压耦合到110TFT的栅极上。以此实现110TFT的Vth补偿过程。
但是该像素补偿电路同时需要2颗电容，其中121电容用来耦合数据电压，122电容用来保存像素电压，以防止漏电。为了达到较好的耦合和电压保持效果，2颗电容的尺寸都需要设计到足够的大小，而在较高像素密度的设计下，电容将占用较大的版图空间，限制了像素密度的提高。
发明内容
本发明的目的在于提供一种减少像素内补偿电路的元器件数量和提高工作寿命的自发光显示装置以及像素内补偿电路。
本发明提供一种像素内补偿电路，其与发光元件连接；所述发光元件位于第一电源和第二电源之间，发光元件由第一发光控制信号和第二发光控制信号进行控制；其特征在于：其包括与所述发光元件连接的第一驱动TFT、位于扫描线和数据线交叉处的第一开关TFT、位于所述第一驱动TFT和第一开关TFT之间的存储电容、第二开关TFT、第三开关TFT、第四开关TFT和接入点；其中，接入点位于第一开关TFT和存储电容之间；第二开关TFT连接在第一电源、第二发光控制信号和第一驱动TFT之间；第三开关TFT与扫描线提供的扫描控制信号连接；第四开关TFT均与参考电压和第一发光控制信号连接；其中在连续的第一时间段、第二时间段、第三时间段和第四时间段内依序第一驱动TFT进行充电、输入 数据电压和第一驱动TFT的阈值电压进行提取、第一驱动TFT的阈值电压进行补偿以及发光元件进入发光阶段。
优选地，所述存储电容为兼具有耦合和存储功能的电容。
优选地，所述第一驱动TFT的通路端连接存储电容的第一端，第一驱动TFT的第一通路端连接第二开关TFT的第一通路端，第一驱动TFT的第二通路端连接发光元件的正极；第一开关TFT的通路端连接扫描线，第一开关TFT的第一通路端连接数据线，第一开关TFT的第二通路端连接存储电容的第二端；第二开关TFT的通路端连接第二发光控制信号，第二开关TFT的第二通路端连接第一电源；第三开关TFT的通路端连接由扫描线提供的扫描控制信号，第三开关TFT的第一通路端连接第二开关TFT的第一通路端，第三开关TFT的第二通路端连接第一驱动TFT的通路端；第四开关TFT的通路端连接第一发光控制信号，第四开关TFT的第一通路端连接参考电压，第四开关TFT的第二通路端连接存储电容的第二端。
优选地，第一开关TFT的第二通路端、存储电容的第二端和第四开关TFT的第二通路端也交汇于接入点；其中，在第一时间段内对像素单元进行预充电，在第三时间段内接入点输入电压并维持为参考电压。
优选地，在第一时间段内扫描线的扫描信号输入高电平，第一发光控制信号输入低电平，第一开关TFT打开，第五开关晶体管关闭，数据电压输入接入点；第三开关TFT和第二开关TFT也处于打开状态，第一驱动TFT的通路端输入第一电源，接入点进行预充电。
优选地，在第二时间段内第二发光控制信号输入低电平，第二开关TFT关闭；第一驱动TFT处于打开状态，第一驱动TFT的通路端和第一通路端连接，第一驱动TFT形成二极管的连接方式；第一驱动TFT的通路端的电荷通过第一驱动TFT向发光元件放电，直至第一驱动TFT的栅极和源极之间的电压降至阈值电压时第一驱动TFT关闭，放电停止。
优选地，在第三时间段内扫描线的扫描信号和扫描控制信号输入低电平，第一发光控制信号输入高电平，第三开关TFT关闭，第一驱动TFT的通路端的电荷被锁定，存储电容的两端压差同时也被锁定；接入点的电压由数据电压变化为参加电压，接入点的电压变化会耦合到第一驱动TFT的通路端。
优选地，在第四时间段内第二发光控制信号输入高电平，第二开关TFT打开，第一电源和第二电源之间形成导电通路，电流流经发光元件而发光。
本发明还提供一种自发光显示装置，其包括N级栅极驱动电路、输出N级的发光控制 电路以及均与栅极驱动电路和发光控制电路连接的像素内补偿电路，所述扫描线的扫描信号接到第n级栅极驱动电路的输出端，第一发光控制信号连接到发光控制电路的第n级输出端，第二发光控制信号连接到发光控制电路的第n+1级输出端，其中，n≤N。
所述像素补偿电路与发光元件连接；所述发光元件位于第一电源和第二电源之间，发光元件由第一发光控制信号和第二发光控制信号进行控制；其特征在于：其包括与所述发光元件连接的第一驱动TFT、位于扫描线和数据线交叉处的第一开关TFT、位于所述第一驱动TFT和第一开关TFT之间的存储电容、第二开关TFT、第三开关TFT、第四开关TFT和接入点；其中，接入点位于第一开关TFT和存储电容之间；第二开关TFT连接在第一电源、第二发光控制信号和第一驱动TFT之间；第三开关TFT与扫描线提供的扫描控制信号连接；第四开关TFT均与参考电压和第一发光控制信号连接；其中在连续的第一时间段、第二时间段、第三时间段和第四时间段内依序第一驱动TFT进行充电、输入数据电压和第一驱动TFT的阈值电压进行提取、第一驱动TFT的阈值电压进行补偿以及发光元件进入发光阶段。
优选地，所述存储电容为兼具有耦合和存储功能的电容。
优选地，所述第一驱动TFT的通路端连接存储电容的第一端，第一驱动TFT的第一通路端连接第二开关TFT的第一通路端，第一驱动TFT的第二通路端连接发光元件的正极；第一开关TFT的通路端连接扫描线，第一开关TFT的第一通路端连接数据线，第一开关TFT的第二通路端连接存储电容的第二端；第二开关TFT的通路端连接第二发光控制信号，第二开关TFT的第二通路端连接第一电源；第三开关TFT的通路端连接由扫描线提供的扫描控制信号，第三开关TFT的第一通路端连接第二开关TFT的第一通路端，第三开关TFT的第二通路端连接第一驱动TFT的通路端；第四开关TFT的通路端连接第一发光控制信号，第四开关TFT的第一通路端连接参考电压，第四开关TFT的第二通路端连接存储电容的第二端。
优选地，所述第一开关TFT的第二通路端、存储电容的第二端和第四开关TFT的第二通路端也交汇于接入点；其中，在第一时间段内对接入点进行预充电，在第三时间段内接入点输入电压并维持为参考电压。
优选地，在第一时间段内扫描线的扫描信号输入高电平，第一发光控制信号输入低电平，第一开关TFT打开，第五开关晶体管关闭，数据电压输入接入点；第三开关TFT和第二开关TFT也处于打开状态，第一驱动TFT的通路端输入第一电源，接入点进行预充电。
优选地，在第二时间段内第二发光控制信号输入低电平，第二开关TFT关闭；第一驱动TFT处于打开状态，第一驱动TFT的通路端和第一通路端连接，第一驱动TFT形成二极管的连接方式；第一驱动TFT的通路端的电荷通过第一驱动TFT向发光元件放电，直至第一驱动TFT的栅极和源极之间的电压降至阈值电压时第一驱动TFT关闭，放电停止。
优选地，在第三时间段内扫描线的扫描信号和扫描控制信号输入低电平，第一发光控制信号输入高电平，第三开关TFT关闭，第一驱动TFT的通路端的电荷被锁定，存储电容的两端压差同时也被锁定；接入点的电压由数据电压变化为参加电压，接入点的电压变化会耦合到第一驱动TFT的通路端。
优选地，在第四时间段内第二发光控制信号输入高电平，第二开关TFT打开，第一电源和第二电源之间形成导电通路，电流流经发光元件而发光。
本申请还提供一种显示设备，包括以上所述的自发光显示装置。该显示设备可以为以下任意一种：手机、平板、笔记本电脑、监视器和电视产品。
本发明通过第一驱动TFT采用二极管的连接方式来提取第一开关TFT的阈值电压Vth，并通过电容耦合作用对第一驱动TFT的驱动电压进行补偿，抵消Vth不均和Vth漂移对显示效果的不良影响；本发明减少像素内补偿电路的元器件数量；提高自发光显示装置的工作寿命。
附图说明
图1所示是现有无补偿像素驱动电路；
图2所示是现有电压控制型像素补偿电路；
图3为本发明像素内补偿电路的结构示意图；
图4为本发明像素内补偿电路的驱动信号波形图；
图5为图4所示驱动信号波形图在第一时间段的结构示意图；
图6为图4所示驱动信号波形图在第二时间段的结构示意图；
图7为图4所示驱动信号波形图在第三时间段的结构示意图；
图8为图4所示驱动信号波形图在第四时间段的结构示意图；
图9为本发明自发光显示装置的结构示意图；
图10为图9所示自发光显示装置的驱动信号波形图；
图11为本发明在不同数据电压下进行电路仿真的结构示意图；
图12为本发明在第一TFT开发的Vth发生变化时进行电路仿真的结构示意图。
具体实施方式
下面结合附图和具体实施例，进一步阐明本发明，应理解这些实施例仅用于说明本发明而不用于限制本发明的范围，在阅读了本发明之后，本领域技术人员对本发明的各种等价形式的修改均落于本申请所附权利要求所限定的范围。
为使图面简洁，各图中只示意性地表示出了与本发明相关的部分，它们并不代表其作为产品的实际结构。另外，以使图面简洁便于理解，在有些图中具有相同结构或功能的部件，仅示意性地绘示了其中的一个，或仅标出了其中的一个。在本文中，“一个”不仅表示“仅此一个”，也可以表示“多于一个”的情形。
图3所示为本发明像素内补偿电路的结构示意图，其用于对自发光显示装置进行补偿，像素内补偿电路与发光元件30连接，其中发光元件30位于第一电源ELVDD和第二电源ELVSS之间，发光元件30由第一发光控制信号EM1和第二发光控制信号EM2进行控制。
其中，第一电源ELVDD为电源正极端，第二电源ELVSS为电源负极端。
自发光显示装置包括纵横交错的扫描线和数据线、由扫描线和数据线交叉限定的像素单元以及位于像素单元内的像素单元；其中扫描线提供扫描信号Scan和扫描控制信号Scan，数据线提供数据电压Vdata。
像素内补偿电路包括与发光元件30连接的第一驱动TFT11、位于扫描线和数据线交叉处的第一开关TFT12、第二开关TFT13、第三开关TFT14、第四开关TFT15、一个存储电容20和接入点(简称为PIX点)，其中，第一驱动TFT11为驱动TFT开关；接入点(简称为PIX点)位于第一开关TFT12、第四开关TFT15和存储电容20三者的交叉处；存储电容20同时兼具有耦合和存储的功能，减少了像素内补偿电路的元件的数量，为更高PPI的自发光显示装置提供了可能性。
需要说明的是，以下实施例所涉及的每个TFT开关均包括通路端、第一通路端和第二通路端，通路端为栅极，其中一个通路端为源极、另一个通路端为漏极。当通路端、第一通路端和第二通路端接收的电压满足TFT开关的打开条件时，源极和漏极通过半导体层连接，此时TFT开关处于打开状态，否则处于关闭状态。
第一驱动TFT11位于发光元件30和第一电源ELVDD之间，与发光元件30以串联方式连接。具体的，第一驱动TFT11的通路端连接存储电容20的第一端，第一驱动TFT11的第一通路端连接第二开关TFT13的第一通路端，第一驱动TFT11的第二通路端连接发光元件30的正极。
第一开关TFT12的通路端连接扫描线，第一开关TFT12的第一通路端连接数据线，第一开关TFT12的第二通路端连接存储电容20的第二端。
第二开关TFT13位于第一驱动TFT11和第一电源ELVDD之间，具体的，第二开关TFT13的通路端连接第二发光控制信号EM2，第二开关TFT13的第二通路端连接第一电源ELVDD，第二开关TFT13的第一通路端连接第一驱动TFT11的第一通路端，实际上，第二开关TFT13、第一驱动TFT11和发光元件30串联在第一电源ELVDD和第二电源ELVSS之间。
第三开关TFT14的通路端连接由扫描线提供的扫描控制信号Scan，第三开关TFT14的第一通路端连接第二开关TFT13的第一通路端，第三开关TFT14的第二通路端连接第一驱动TFT11的通路端，即第一驱动TFT11的第一通路端、第三开关TFT14的第一通路端和第二开关TFT13的第一通路端交汇于一点。
第四开关TFT15的通路端连接第一发光控制信号EM1，第四开关TFT15的第一通路端连接参考电压Vref，第四开关TFT15的第二通路端连接存储电容20的第二端，即第一开关TFT12的第二通路端、存储电容20的第二端和第四开关TFT15的第二通路端也交汇于PIX点。
其中，第一驱动TFT11的通路端为G点，存储电容20的第一端和第三开关TFT14的第二通路端也交汇于G点；第一驱动TFT11的第一通路端为A点，第一驱动TFT11的第一通路端、第三开关TFT14的第一通路端和第二开关TFT13的第一通路端交汇于A点；第一驱动TFT11的第二通路端为B点，第一驱动TFT11的第二通路端和发光元件30的正极交汇于B点。
如图4所示为本发明像素内补偿电路的驱动信号波形图，其中，在连续的第一时间段(具体为T1期间)、第二时间段(具体为T2期间)、第三时间段(具体为T3期间)和第四时间段(具体为T4期间)内依序对PIX点进行预充电和对第一驱动TFT11的通路端G点进行充电、输入数据电压Vdata和对第一驱动TFT11的通路端G点的阈值电压Vth进行提取、PIX点输入并维持为参考电压Vref和对第一驱动TFT11的通路端G点的阈值电压Vth进行补偿以及发光元件30进入发光阶段。
具体的，第一时间段(具体为T1期间)内对PIX点(即接入点)进行预充电，第一驱动TFT11的通路端G点进行充电；第二时间段(具体为T2期间)内通过数据线输入数据电压Vdata，第一驱动TFT11的通路端G点对Vth进行提取；第三时间段(具体为T3 期间)内PIX点(即接入点)输入维持参考电压Vref，第一驱动TFT11的通路端G点的Vth进行补偿；第四时间段(具体为T4期间)为发光元件30进入发光阶段；T1、T2和T3的时间长度相同，T4不小于T1、T2和T3的时间之和。
扫描线的扫描信号Scan和扫描控制信号Scan在T1期间和T2期间为高电平时，在T3期间和T4期间为低电平；第一发光控制信号EM1在T1期间和T2期间为低电平，在T3期间和T4期间为高电平；第二发光控制信号EM2在T1期间和T4期间为高电平，在T2期间和T3期间都为低电平；数据电压Vdata在T2期间为高电平，T1期间、T3期间和T4期间为低电平。
如图5所示，在T1期间，扫描线的扫描信号Scan输入高电平，第一发光控制信号EM1输入低电平，此时，第一开关TFT12打开，第五开关晶体管15关闭，数据电压Vdata输入PIX点；与此同时，第三开关TFT14和第二开关TFT13也处于打开状态，第一驱动TFT11的通路端G点相当于直接输入第一电源ELVDD，PIX点进行预充电。
如图6所示，在T2期间，第二发光控制信号EM2输入低电平，此时第二开关TFT13关闭；第一驱动TFT11处于打开状态，第一驱动TFT11的通路端和第一通路端连接，第一驱动TFT11形成二极管的连接方式，第一驱动TFT11的通路端G点的电荷通过第一驱动TFT11向发光元件30放电，直至第一驱动TFT11的Vgs(栅极和源极之间的)电压降至Vth时第一驱动TFT11关闭，放电停止，此时第一驱动TFT11的通路端G点的电压为(ELVSS+Voled+Vth)，Voled为发光元件30的电压；至此，第一驱动TFT11的通路端G点的Vth成功提取到第一驱动TFT11的通路端G点，并由存储电容20的电容Cst保存下来。
如图7所示，在T3时间，扫描线的扫描信号Scan和扫描控制信号Scan输入低电平，第一发光控制信号EM1输入高电平，此时第三开关TFT14关闭，第一驱动TFT11的通路端G点的电荷被锁定，存储电容20的电容Cst两端压差同时也被锁定；与此同时，PIX点的电压由Vdata变化为Vref，由于存储电容20的电容Cst两端的压差被锁定，PIX点的电压变化会耦合到第一驱动TFT11的通路端G点，因此第一驱动TFT11的通路端G点的电压变化为(ELVSS+Voled+Vth+Vref-Vdata)。
如图8所示，在T4阶段，第二发光控制信号EM2输入高电平，第二开关TFT13打开，第一电源ELVDD和第二电源ELVSS之间形成导电通路，电流流经发光元件30而发光，即进入发光阶段。
在发光阶段，流经发光元件30的电流由第一驱动TFT11控制。由于第一驱动TFT11的第一通路端电压为ELVDD，第一驱动TFT11工作在饱和区，其工作电流为1/2K(Vgs-Vth)2，即1/2K(Vref-Vdata)2。通过该电流公式，可以发现流经发光元件30的驱动电流仅仅只与Vdata电压和Vref电压有关，Vref为恒定参考电压，驱动电流实际上仅受Vdata电压控制。由于T2期间对第一驱动TFT11的Vth进行了提取，发光阶段的电流不受第一驱动TFT11的Vth影响，实现了Vth的补偿效果。
在Vth补偿之后，发光亮度不受工艺制程均一性造成的Vth偏差影响，使显示区的发光亮度更加均匀，实现更好的画质表现。同时由于Vth得到补偿，在长时间工作后，即使第一驱动TFT11的Vth发生漂移，其亮度也不会受到明显影响，提高了自发光显示装置的工作寿命和信赖性。
本发明还揭示一种自发光显示装置，其包括N级栅极驱动电路、输出N级的发光控制电路以及均与栅极驱动电路和发光控制电路连接的像素内补偿电路。
图9所示为本发明自发光显示装置的结构示意图，扫描线Scan的扫描信号接到第n级栅极驱动电路的输出端Gn，第一发光控制信号EM1连接到发光控制电路的第n级输出端EMn，第二发光控制信号EM2连接到发光控制电路的第n+1级输出端EMn+1，其中，n≤N。
图10为图9所示自发光显示装置的驱动信号波形图，其与图4所示的驱动信号波形图相同，即第n级栅极驱动电路的输出端Gn是时序与扫描线Scan的扫描信号的时序相同，发光控制电路的第n级输出端EMn的时序与第一发光控制信号EM1的时序相同，发光控制电路的第n+1级输出端EMn+1的时序与第二发光控制信号EM2的时序相同。
图11和图12为自发光显示装置的电路仿真结果的示意图，在采用本发明像素内补偿电路之后，图11为不同Vdata电压下的驱动电流变化，仿真结果显示Vdata电压可以正常控制像素电路的驱动电流。图12为当第一驱动TFT的Vth发生变化时，不同Vth下的驱动电流变化，可以看到，在较大的Vth电压变化范围内，各个灰阶的驱动电流均保持了比较好的稳定性，而没有发生明显的电流衰减。
本发明像素内补偿电路同时还能补偿第一电源ELVDD的波动影响。由于自发光显示器件靠电流驱动，第一电源ELVDD和第二电源ELVSS均需提供较大的电流。电流在流经导电通路时，将产生电压降IR-drop，此电压降将导致显示区每个像素实际得到的第一电源ELVDD和第二电源ELVSS产生差异，造成显示效果的不均。
本发明像素内补偿电路的驱动电流只与Vdata电压有关，补偿掉了第一电源ELVDD和 第二电源ELVSS，避免了IR-drop造成的画面不均，有利于实现更好的画面显示效果。
本发明像素内补偿电路同时还能补偿发光元件的阈值电压。发光元件的阈值电压在长时间工作后会发生漂移，导致显示亮度降低；本发明像素内补偿电路补偿了发光元件的阈值电压Voled，其驱动电流仅与Vdata有关，避免了发光器件老化造成的亮度降低。提高了显示器件的寿命。
本发明像素内补偿电路应用范围包括但不限于有机发光二极管、Micro-LED、量子点LED等自发光型平板显示器，所使用的半导体技术包括但不限于a-Si:H、oxide、LTPS。
本发明通过第一驱动TFT采用二极管的连接方式来提取第一开关TFT的阈值电压Vth，并通过电容耦合作用对第一驱动TFT的驱动电压进行补偿，抵消Vth不均和Vth漂移对显示效果的不良影响；本发明减少像素内补偿电路的元器件数量；提高自发光显示装置的工作寿命。
本申请还提供一种显示设备，包括以上所述的自发光显示装置。该显示设备可以为以下任意一种：手机、平板、笔记本电脑、监视器和电视产品。
以上详细描述了本发明的优选实施方式，但是本发明并不限于上述实施方式中的具体细节，在本发明的技术构思范围内，可以对本发明的技术方案进行多种等同变换(如数量、形状、位置等)，这些等同变换均属于本发明的保护范围。

Claims (17)

  1. 一种像素内补偿电路，其与发光元件连接；所述发光元件位于第一电源和第二电源之间，发光元件由第一发光控制信号和第二发光控制信号进行控制；其特征在于：其包括与所述发光元件连接的第一驱动TFT、位于扫描线和数据线交叉处的第一开关TFT、位于所述第一驱动TFT和第一开关TFT之间的存储电容、第二开关TFT、第三开关TFT、第四开关TFT和接入点；其中，接入点位于第一开关TFT和存储电容之间；第二开关TFT连接在第一电源、第二发光控制信号和第一驱动TFT之间；第三开关TFT与扫描线提供的扫描控制信号连接；第四开关TFT均与参考电压和第一发光控制信号连接；其中在连续的第一时间段、第二时间段、第三时间段和第四时间段内依序第一驱动TFT进行充电、输入数据电压和第一驱动TFT的阈值电压进行提取、第一驱动TFT的阈值电压进行补偿以及发光元件进入发光阶段。
  2. 根据权利要求1所述的像素内补偿电路，其特征在于，所述存储电容为兼具有耦合和存储功能的电容。
  3. 根据权利要求2所述的像素内补偿电路，其特征在于，所述第一驱动TFT的通路端连接存储电容的第一端，第一驱动TFT的第一通路端连接第二开关TFT的第一通路端，第一驱动TFT的第二通路端连接发光元件的正极；第一开关TFT的通路端连接扫描线，第一开关TFT的第一通路端连接数据线，第一开关TFT的第二通路端连接存储电容的第二端；第二开关TFT的通路端连接第二发光控制信号，第二开关TFT的第二通路端连接第一电源；第三开关TFT的通路端连接由扫描线提供的扫描控制信号，第三开关TFT的第一通路端连接第二开关TFT的第一通路端，第三开关TFT的第二通路端连接第一驱动TFT的通路端；第四开关TFT的通路端连接第一发光控制信号，第四开关TFT的第一通路端连接参考电压，第四开关TFT的第二通路端连接存储电容的第二端。
  4. 根据权利要求3所述的像素内补偿电路，其特征在于，所述第一开关TFT的第二通路端、存储电容的第二端和第四开关TFT的第二通路端也交汇于接入点；其中，在第一时间段内对接入点进行预充电，在第三时间段内接入点输入电压并维持为参考电压。
  5. 根据权利要求3所述的像素内补偿电路，其特征在于，在第一时间段内扫描线的扫描信号输入高电平，第一发光控制信号输入低电平，第一开关TFT打开，第五开关晶体管关闭，数据电压输入接入点；第三开关TFT和第二开关TFT也处于打开状态，第一驱动TFT的通路端输入第一电源，接入点进行预充电。
  6. 根据权利要求5所述的像素内补偿电路，其特征在于，在第二时间段内第二发光控制信号输入低电平，第二开关TFT关闭；第一驱动TFT处于打开状态，第一驱动TFT的通路端和第一通路端连接，第一驱动TFT形成二极管的连接方式；第一驱动TFT的通路端的电荷通过第一驱动TFT向发光元件放电，直至第一驱动TFT的栅极和源极之间的电压降至阈值电压时第一驱动TFT关闭，放电停止。
  7. 根据权利要求6所述的像素内补偿电路，其特征在于，在第三时间段内扫描线的扫描信号和扫描控制信号输入低电平，第一发光控制信号输入高电平，第三开关TFT关闭，第一驱动TFT的通路端的电荷被锁定，存储电容的两端压差同时也被锁定；接入点的电压由数据电压变化为参加电压，接入点的电压变化会耦合到第一驱动TFT的通路端。
  8. 根据权利要求7所述的像素内补偿电路，其特征在于，在第四时间段内第二发光控制信号输入高电平，第二开关TFT打开，第一电源和第二电源之间形成导电通路，电流流经发光元件而发光。
  9. 一种自发光显示装置，其包括N级栅极驱动电路、输出N级的发光控制电路以及均与栅极驱动电路和发光控制电路连接的像素内补偿电路，所述扫描线的扫描信号接到第n级栅极驱动电路的输出端，第一发光控制信号连接到发光控制电路的第n级输出端，第二发光控制信号连接到发光控制电路的第n+1级输出端，其中，n≤N；
    所述像素补偿电路与发光元件连接；所述发光元件位于第一电源和第二电源之间，发光元件由第一发光控制信号和第二发光控制信号进行控制；其特征在于：其包括与所述发光元件连接的第一驱动TFT、位于扫描线和数据线交叉处的第一开关TFT、位于所述第一驱动TFT和第一开关TFT之间的存储电容、第二开关TFT、第三开关TFT、第四开关TFT和接入点；其中，接入点位于第一开关TFT和存储电容之间；第二开关TFT连接在第一电源、第二发光控制信号和第一驱动TFT之间；第三开关TFT与扫描线提供的扫描控制信号连接；第四开关TFT均与参考电压和第一发光控制信号连接；其中在连续的第一时间段、第二时间段、第三时间段和第四时间段内依序第一驱动TFT进行充电、输入数据电压和第一驱动TFT的阈值电压进行提取、第一驱动TFT的阈值电压进行补偿以及发光元件进入发光阶段。
  10. 根据权利要求9所述的自发光显示装置，其特征在于，所述存储电容为兼具有耦合和存储功能的电容。
  11. 根据权利要求10所述的自发光显示装置，其特征在于，所述第一驱动TFT的 通路端连接存储电容的第一端，第一驱动TFT的第一通路端连接第二开关TFT的第一通路端，第一驱动TFT的第二通路端连接发光元件的正极；第一开关TFT的通路端连接扫描线，第一开关TFT的第一通路端连接数据线，第一开关TFT的第二通路端连接存储电容的第二端；第二开关TFT的通路端连接第二发光控制信号，第二开关TFT的第二通路端连接第一电源；第三开关TFT的通路端连接由扫描线提供的扫描控制信号，第三开关TFT的第一通路端连接第二开关TFT的第一通路端，第三开关TFT的第二通路端连接第一驱动TFT的通路端；第四开关TFT的通路端连接第一发光控制信号，第四开关TFT的第一通路端连接参考电压，第四开关TFT的第二通路端连接存储电容的第二端。
  12. 根据权利要求11所述的自发光显示装置，其特征在于，所述第一开关TFT的第二通路端、存储电容的第二端和第四开关TFT的第二通路端也交汇于接入点；其中，在第一时间段内对接入点进行预充电，在第三时间段内接入点输入电压并维持为参考电压。
  13. 根据权利要求11所述的自发光显示装置，其特征在于，在第一时间段内扫描线的扫描信号输入高电平，第一发光控制信号输入低电平，第一开关TFT打开，第五开关晶体管关闭，数据电压输入接入点；第三开关TFT和第二开关TFT也处于打开状态，第一驱动TFT的通路端输入第一电源，接入点进行预充电。
  14. 根据权利要求13所述的自发光显示装置，其特征在于，在第二时间段内第二发光控制信号输入低电平，第二开关TFT关闭；第一驱动TFT处于打开状态，第一驱动TFT的通路端和第一通路端连接，第一驱动TFT形成二极管的连接方式；第一驱动TFT的通路端的电荷通过第一驱动TFT向发光元件放电，直至第一驱动TFT的栅极和源极之间的电压降至阈值电压时第一驱动TFT关闭，放电停止。
  15. 根据权利要求14所述的自发光显示装置，其特征在于，在第三时间段内扫描线的扫描信号和扫描控制信号输入低电平，第一发光控制信号输入高电平，第三开关TFT关闭，第一驱动TFT的通路端的电荷被锁定，存储电容的两端压差同时也被锁定；接入点的电压由数据电压变化为参加电压，接入点的电压变化会耦合到第一驱动TFT的通路端。
  16. 根据权利要求15所述的自发光显示装置，其特征在于，在第四时间段内第二发光控制信号输入高电平，第二开关TFT打开，第一电源和第二电源之间形成导电通路，电流流经发光元件而发光。
  17. 一种显示设备，其特征在于，包括权利要求9所述的自发光显示装置。
PCT/CN2020/086364 2019-11-25 2020-04-23 一种自发光显示装置以及像素内补偿电路 WO2021103406A1 (zh)

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