WO2018152893A1 - Oled像素驱动电路及oled显示装置 - Google Patents

Oled像素驱动电路及oled显示装置 Download PDF

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Publication number
WO2018152893A1
WO2018152893A1 PCT/CN2017/076778 CN2017076778W WO2018152893A1 WO 2018152893 A1 WO2018152893 A1 WO 2018152893A1 CN 2017076778 W CN2017076778 W CN 2017076778W WO 2018152893 A1 WO2018152893 A1 WO 2018152893A1
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Prior art keywords
film transistor
thin film
pin
signal
electrically connected
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French (fr)
Inventor
邝继木
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Shenzhen China Star Optoelectronics Semiconductor Display Technology Co Ltd
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Shenzhen China Star Optoelectronics Semiconductor Display Technology Co Ltd
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Priority to US15/519,837 priority Critical patent/US10147356B2/en
Publication of WO2018152893A1 publication Critical patent/WO2018152893A1/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]
    • G09G3/3208—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED]
    • G09G3/3225—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED] using an active matrix
    • G09G3/3258—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED] using an active matrix with pixel circuitry controlling the voltage across the light-emitting element
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
    • G09G3/30—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels
    • G09G3/32—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED]
    • G09G3/3208—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED]
    • G09G3/3225—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED] using an active matrix
    • G09G3/3233—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED] using an active matrix with pixel circuitry controlling the current through the light-emitting element
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
    • G09G3/30—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels
    • G09G3/32—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED]
    • G09G3/3208—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED]
    • G09G3/3275—Details of drivers for data electrodes
    • G09G3/3283—Details of drivers for data electrodes in which the data driver supplies a variable data current for setting the current through, or the voltage across, the light-emitting elements
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2300/00—Aspects of the constitution of display devices
    • G09G2300/04—Structural and physical details of display devices
    • G09G2300/0439—Pixel structures
    • G09G2300/0465—Improved aperture ratio, e.g. by size reduction of the pixel circuit, e.g. for improving the pixel density or the maximum displayable luminance or brightness
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2300/00—Aspects of the constitution of display devices
    • G09G2300/08—Active matrix structure, i.e. with use of active elements, inclusive of non-linear two terminal elements, in the pixels together with light emitting or modulating elements
    • G09G2300/0809—Several active elements per pixel in active matrix panels
    • G09G2300/0819—Several active elements per pixel in active matrix panels used for counteracting undesired variations, e.g. feedback or autozeroing
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2300/00—Aspects of the constitution of display devices
    • G09G2300/08—Active matrix structure, i.e. with use of active elements, inclusive of non-linear two terminal elements, in the pixels together with light emitting or modulating elements
    • G09G2300/0809—Several active elements per pixel in active matrix panels
    • G09G2300/0842—Several active elements per pixel in active matrix panels forming a memory circuit, e.g. a dynamic memory with one capacitor
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2310/00—Command of the display device
    • G09G2310/02—Addressing, scanning or driving the display screen or processing steps related thereto
    • G09G2310/0264—Details of driving circuits
    • G09G2310/027—Details of drivers for data electrodes, the drivers handling digital grey scale data, e.g. use of D/A converters
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2310/00—Command of the display device
    • G09G2310/08—Details of timing specific for flat panels, other than clock recovery
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/02—Improving the quality of display appearance
    • G09G2320/0233—Improving the luminance or brightness uniformity across the screen
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/04—Maintaining the quality of display appearance
    • G09G2320/043—Preventing or counteracting the effects of ageing
    • G09G2320/045—Compensation of drifts in the characteristics of light emitting or modulating elements

Definitions

  • the present invention relates to the field of display technologies, and in particular, to an OLED pixel driving circuit and an OLED display device.
  • OLED Organic Light Emitting Display
  • OLED Organic Light Emitting Display
  • the OLED is a current driving device.
  • the organic light emitting diode emits light, and the luminance of the light is determined by the current flowing through the organic light emitting diode itself.
  • Most existing integrated circuits (ICs) only transmit voltage signals, so the pixel driving circuit of the OLED needs to complete the task of converting the voltage signal into a current signal.
  • the conventional OLED pixel driving circuit is usually 2T1C, that is, a structure in which two thin film transistors are added with a capacitor to convert a voltage into a current.
  • a conventional 2T1C pixel driving circuit for an OLED includes: a first thin film transistor T10, a second thin film transistor T20, and a capacitor C10, the first thin film transistor T10 is a switching thin film transistor, and the second The thin film transistor T20 is a driving thin film transistor, and the capacitor C10 is a storage capacitor.
  • the gate of the first thin film transistor T10 is connected to the scan signal Scan, the drain is connected to the data signal Data, the source is electrically connected to the gate of the second thin film transistor T20, and one end of the capacitor C10; the second The drain of the thin film transistor T20 is connected to the power supply voltage OVDD, the source is electrically connected to the anode of the organic light emitting diode D10, the cathode of the organic light emitting diode D10 is connected to the common ground voltage OVSS, and one end of the capacitor C10 is electrically connected to the second thin film transistor T20.
  • the gate is electrically connected to the source of the second thin film transistor T20.
  • the scan signal Scan controls the first thin film transistor T10 to be turned on, and the data signal Data passes through the first thin film transistor T10 to enter the gate of the second thin film transistor T20 and the capacitor C10, and then the first thin film transistor T10 is turned off due to the capacitor C10.
  • the gate voltage of the second thin film transistor T20 can continue to maintain the data signal voltage, so that the second thin film transistor T20 is in an on state, and the driving current enters the organic light emitting diode D10 through the second thin film transistor T20 to drive the organic light emitting diode. D10 shines.
  • I OLED K ⁇ (Vgs - Vth) 2
  • I OLED represents the current flowing through the driving thin film transistor and the organic light emitting diode
  • K is the intrinsic conductive factor of the driving thin film transistor
  • Vgs represents the voltage difference between the gate and the source of the driving thin film transistor
  • Vth represents the driving thin film transistor Threshold voltage. It can be seen that the size of the I OLED is related to the threshold voltage Vth of the driving thin film transistor.
  • the above-mentioned conventional OLED pixel driving circuit has a simple structure and does not have a compensation function, so there are many defects, and among them, the driving thin film transistor of each pixel in the OLED display device is relatively obvious due to non-uniformity in the manufacturing process of the thin film transistor.
  • the threshold voltages are inconsistent; and the long-term operation causes the material of the driving thin film transistor to age, which causes the threshold voltage of the driving thin film transistor to drift, which may cause display unevenness.
  • FIG. 2 shows an existing OLED pixel driving circuit with a compensation function of a 3T1C structure.
  • a third thin film transistor T30 is added, and the third thin film transistor T30 is added.
  • the gate is connected to the sensing control signal Sense, the source is electrically connected to the source of the second thin film transistor T20, the drain is electrically connected to the analog-to-digital converter ADC and is connected to the reference voltage signal Vref, and the data signal Data is converted by digital-to-analog
  • the DAC is provided.
  • the 3T1C structure OLED pixel driving circuit can sense the threshold voltage Vth of the driving thin film transistor and compensate the Vth value into the data signal Data, so that the threshold voltage Vth of the driving thin film transistor can be eliminated to the current flowing through the organic light emitting diode I OLED The effect of the display is even and the image quality is improved.
  • the shortcomings of the 3T1C structure OLED pixel driving circuit are as follows:
  • the reference voltage signal Vref provides a reference voltage for each pixel, and the trace causes the aperture ratio of the pixel to decrease.
  • the generation of the reference voltage signal Vref increases the number of channels of the driving IC, and the manufacturing cost increases.
  • An object of the present invention is to provide an OLED pixel driving circuit that not only has a compensation function, but also can eliminate the influence of the threshold voltage of the driving thin film transistor on the current flowing through the organic light emitting diode, improve display uniformity, and can improve the aperture ratio of the pixel and reduce manufacturing cost.
  • Another object of the present invention is to provide an OLED display device in which a pixel driving circuit has a compensation function, a display uniformity is good, a pixel aperture ratio is high, and a manufacturing cost is low.
  • the present invention firstly provides an OLED pixel driving circuit including a first thin film transistor, a second thin film transistor, a third thin film transistor, a capacitor, an organic light emitting diode, and a switching switch and a digital mode disposed in the driving IC. a converter, and an analog to digital converter; the operating state of the OLED pixel driving circuit includes a display mode and a sensing mode;
  • the switch is controlled by a switching signal, including a first pin, a second pin, and a third pin;
  • the gate of the first thin film transistor is connected to the scan signal, the drain is connected to the power supply voltage, the source is electrically connected to the gate of the second thin film transistor, and one end of the capacitor; and the drain of the second thin film transistor is connected Into the power supply voltage, the source is electrically connected to the anode of the organic light emitting diode; the cathode of the organic light emitting diode is connected to the common ground voltage; the other end of the capacitor is electrically connected to the source of the second thin film transistor; the gate of the third thin film transistor is displayed
  • the mode is connected to the scan signal, and the sensing control signal is connected in the sensing mode, the source is electrically connected to the source of the second thin film transistor, and the drain is electrically connected to the first pin of the switch;
  • the second pin of the switch is electrically connected to the digital-to-analog converter, and the third pin is electrically connected to the analog-to-digital converter;
  • the switching signal control switch is turned on to the first pin and the second pin, and the digital-to-analog converter provides a data signal; in the sensing mode, the digital-to-analog converter first provides a low-potential signal, and then switches the signal.
  • the control switch turns on the first pin and the third pin, so that the analog-to-digital converter senses the threshold voltage of the second thin film transistor.
  • the potential of the data signal is not higher than a threshold voltage of the organic light emitting diode, and the power supply voltage is higher than a sum of a threshold voltage of the organic light emitting diode and a threshold voltage of the second thin film transistor.
  • the threshold voltage of the organic light emitting diode is 10V.
  • the scan signal first provides a high potential pulse and then remains low; the common ground voltage is always low; the data signal continues to be high from the rising edge of the high potential pulse of the scan signal ;
  • the scan signal first provides a high potential pulse and then remains low;
  • the sensing control signal first provides a high potential pulse synchronized with the high potential pulse of the scan signal, and then remains low.
  • the common ground voltage first provides a high potential pulse synchronized with the high potential pulse of the sensing control signal, and then remains low.
  • the present invention also provides an OLED display device including an OLED pixel driving circuit, the OLED pixel driving circuit including a first thin film transistor, a second thin film transistor, a third thin film transistor, a capacitor, an organic light emitting diode, and a driver IC Switching switch, digital-to-analog converter, and analog-to-digital converter; the working state of the OLED pixel driving circuit includes a display mode and a sensing mode;
  • the switch is controlled by a switching signal, including a first pin, a second pin, and a third pin;
  • the gate of the first thin film transistor is connected to the scan signal, the drain is connected to the power supply voltage, and the source is Connected to the gate of the second thin film transistor and one end of the capacitor;
  • the drain of the second thin film transistor is connected to the power supply voltage, the source is electrically connected to the anode of the organic light emitting diode; and the cathode of the organic light emitting diode is connected to the common Grounding voltage;
  • the other end of the capacitor is electrically connected to the source of the second thin film transistor;
  • the gate of the third thin film transistor is connected to the scan signal in the display mode, and the sensing control signal is connected in the sensing mode, and the source is electrically Connecting a source of the second thin film transistor, and electrically connecting the drain to the first pin of the switch;
  • the second pin of the switch is electrically connected to the digital-to-analog converter, and the third pin is electrically connected to the analog-to-digital converter;
  • the switching signal control switch is turned on to the first pin and the second pin, and the digital-to-analog converter provides a data signal; in the sensing mode, the digital-to-analog converter first provides a low-potential signal, and then switches the signal.
  • the control switch turns on the first pin and the third pin, so that the analog-to-digital converter senses the threshold voltage of the second thin film transistor.
  • the potential of the data signal is not higher than a threshold voltage of the organic light emitting diode, and the power supply voltage is higher than a sum of a threshold voltage of the organic light emitting diode and a threshold voltage of the second thin film transistor.
  • the threshold voltage of the organic light emitting diode is 10V.
  • the scan signal first provides a high potential pulse and then remains low; the common ground voltage is always low; the data signal continues to be high from the rising edge of the high potential pulse of the scan signal ;
  • the scan signal first provides a high potential pulse and then remains low;
  • the sensing control signal first provides a high potential pulse synchronized with the high potential pulse of the scan signal, and then remains low.
  • the common ground voltage first provides a high potential pulse synchronized with the high potential pulse of the sensing control signal, and then remains low.
  • the present invention also provides an OLED pixel driving circuit including a first thin film transistor, a second thin film transistor, a third thin film transistor, a capacitor, an organic light emitting diode, and a switch, a digital to analog converter, and a mode disposed in the driving IC. a digital converter; the operating state of the OLED pixel driving circuit includes a display mode and a sensing mode;
  • the switch is controlled by a switching signal, including a first pin, a second pin, and a third pin;
  • the gate of the first thin film transistor is connected to the scan signal, the drain is connected to the power supply voltage, the source is electrically connected to the gate of the second thin film transistor, and one end of the capacitor; and the drain of the second thin film transistor is connected Into the power supply voltage, the source is electrically connected to the anode of the organic light emitting diode; the cathode of the organic light emitting diode is connected to the common ground voltage; the other end of the capacitor is electrically connected to the source of the second thin film transistor; the gate of the third thin film transistor is displayed Mode access to scan signal, in sensing mode The sensing control signal is connected, the source is electrically connected to the source of the second thin film transistor, and the drain is electrically connected to the first pin of the switching switch;
  • the second pin of the switch is electrically connected to the digital-to-analog converter, and the third pin is electrically connected to the analog-to-digital converter;
  • the switching signal control switch is turned on to the first pin and the second pin, and the digital-to-analog converter provides a data signal; in the sensing mode, the digital-to-analog converter first provides a low-potential signal, and then switches the signal. Controlling the switch to turn on the first pin and the third pin, so that the analog-to-digital converter senses the threshold voltage of the second thin film transistor;
  • the potential of the data signal is not higher than a threshold voltage of the organic light emitting diode, and the power supply voltage is higher than a sum of a threshold voltage of the organic light emitting diode and a threshold voltage of the second thin film transistor;
  • the threshold voltage of the organic light emitting diode is 10V
  • the scan signal first provides a high potential pulse, and then remains low; the common ground voltage is always low; the data signal continues from the rising edge of the high potential pulse of the scan signal High potential
  • the scan signal first provides a high potential pulse and then remains low;
  • the sensing control signal first provides a high potential pulse synchronized with the high potential pulse of the scan signal, and then remains low.
  • the OLED pixel driving circuit and the OLED display device provided by the present invention add a third thin film transistor and a switching switch based on the 2T1C structure, and the first pin of the switching switch is electrically connected to the third film.
  • the drain of the transistor, the second pin is electrically connected to the digital-to-analog converter, and the third pin is electrically connected to the analog-to-digital converter, and the switching pin is controlled to switch on the first pin and the second pin to enter the display mode, Controlling the switch by switching the signal to turn on the first pin and the third pin to enter the sensing mode, so that the analog-to-digital converter senses the threshold voltage of the second thin film transistor, and is used for data in the display mode after analog-to-digital conversion Compensation, thereby having a compensation function, can eliminate the influence of the threshold voltage of the driving thin film transistor on the current flowing through the organic light emitting diode, improve display uniformity, and eliminate the need to additionally set the reference voltage signal as in the prior art, thereby also improving the opening of
  • 1 is a circuit diagram of a conventional 2T1C pixel driving circuit for an OLED
  • FIG. 2 is a circuit diagram of a conventional OLED pixel driving circuit of a 3T1C structure having a compensation function
  • FIG. 3 is a circuit diagram of an OLED pixel driving circuit of the present invention.
  • FIG. 4 is a circuit connection diagram of the OLED pixel driving circuit of the present invention in a display mode
  • FIG. 5 is a timing diagram of the OLED pixel driving circuit of the present invention in a display mode
  • FIG. 6 is a circuit connection diagram of an OLED pixel driving circuit of the present invention in a sensing mode
  • FIG. 7 is a timing diagram of the OLED pixel driving circuit of the present invention in a sensing mode.
  • the present invention provides an OLED pixel driving circuit.
  • the OLED pixel driving circuit of the present invention includes a first thin film transistor T1, a second thin film transistor T2, a third thin film transistor T3, a capacitor C1, an organic light emitting diode D1, and
  • the switch K, the digital-to-analog converter DAC, and the analog-to-digital converter ADC in the drive IC 10 are driven.
  • the second thin film transistor T2 is a driving thin film transistor that directly drives the organic light emitting diode D1.
  • the OLED pixel driving circuit adds a third thin film transistor T3 and sets a switching switch K based on the 2T1C structure, and its working state includes a display mode and a sensing mode.
  • the switch K is controlled by the switching signal Switch, and includes a first pin K1, a second pin K2, and a third pin K3;
  • the gate of the first thin film transistor T1 is connected to the scan signal Scan, the drain is connected to the power supply voltage OVDD, the source is electrically connected to the gate of the second thin film transistor T2, and one end of the capacitor C1; the second film
  • the drain of the transistor T2 is connected to the power supply voltage OVDD, the source is electrically connected to the anode of the organic light emitting diode D1, the cathode of the organic light emitting diode D1 is connected to the common ground voltage OVSS, and the other end of the capacitor C1 is electrically connected to the second thin film transistor T2.
  • the gate of the third thin film transistor T3 is connected to the scan signal Scan in the display mode, the sense control signal Sense is connected in the sensing mode, and the source is electrically connected to the source and drain of the second thin film transistor T2. Electrically connecting the first pin K1 of the switch K;
  • the second pin K2 of the switch K is electrically connected to the digital-to-analog converter DAC, and the third pin K3 is electrically connected to the analog-to-digital converter ADC.
  • the first thin film transistor T1, the second thin film transistor T2, and the third thin film transistor T3 are both low temperature polysilicon thin film transistors, oxide semiconductor thin film transistors, or amorphous silicon thin film crystals. Body tube.
  • the switching signal Switch controls the switch K to turn on the first pin K1 and the second pin K2, and the digital-to-analog converter DAC provides the data signal Data.
  • the scan signal Scan first provides a high potential pulse, so that both the first thin film transistor T1 and the third thin film transistor T3 are turned on.
  • the data signal Data continues to be at a high potential from the rising edge of the high-potential pulse of the scan signal Scan, and the data signal Data is written by the first pin K1 of the switch K and the second pin K2 and the turned-on third thin film transistor T3.
  • the source s of the second thin film transistor T2, that is, Vs V Data (Vs represents the potential of the source s of the second thin film transistor T2, and V Data represents the potential of the data signal Data).
  • the scan signal Scan is kept at a low potential, so that both the first thin film transistor T1 and the third thin film transistor T3 are turned off, and the organic light emitting diode D1 emits light for display by the storage function of the capacitor C1.
  • the common ground voltage OVSS is always low; the potential V Data of the data signal Data is not higher than the threshold voltage Vth- OLED of the organic light emitting diode D1, that is, V Data ⁇ Vth- OLED , Further, the threshold voltage Vth- OLED of the organic light emitting diode D1 is about 10 V (three-layer or four-layer organic light-emitting diodes for the light-emitting layer), so that the second film can be ensured during the data signal Data writing process.
  • a source electrode s of the transistor T2 is the potential Vs of the organic light emitting diode D1 does not light up; the power supply voltage is higher than the organic light emitting diode D1 OVDD threshold voltage Vth- OLED and the second thin film transistor and the threshold voltage Vth of the sum of T2, i.e. OVDD >Vth- OLED +Vth, such that after the data signal Data is written, the voltage Vgs between the gate g and the source s of the second thin film transistor T2 is:
  • the organic light emitting diode D1 can normally emit light and display.
  • the scan signal Scan first provides a high potential pulse to turn on the first thin film transistor T1, and the power supply voltage OVDD enters the second thin film transistor through the turned-on first thin film transistor T1.
  • the gate g of T2, that is, Vg OVDD; the sensing control signal Sense first provides a high-potential pulse synchronized with the high-potential pulse of the scan signal Scan to turn on the third thin film transistor T3, and the switching signal Switch is first maintained.
  • the switch K turns on the first pin K1 and the second pin K2, and the digital-to-analog converter DAC first provides a low potential signal through the first pin K1 and the second pin K2 of the switch K, and the first pass
  • the third thin film transistor T3 is written to the source s of the second thin film transistor T2, and the common ground voltage OVSS first provides a high potential pulse synchronized with the high potential pulse of the sensing control signal Sense to ensure that the organic light emitting diode D1 cannot be Light up.
  • the switching signal Switch controls the switch K to turn on the first pin K1 and The third pin K3, at this time, since the potential of the gate g of the second thin film transistor T2 is OVDD, and the source s is at a lower potential, the analog-to-digital converter ADC passes through the turned-on third thin film transistor T3, and switches The first pin K1 and the third pin K3 of the switch K can sense the threshold voltage Vth of the second thin film transistor T2, that is, the driving thin film transistor. After that, the scan signal Scan, the sense control signal Sense, and the common ground voltage OVSS are both turned to a low potential and held.
  • the analog-to-digital converter ADC senses the threshold voltage Vth of the second thin film transistor T2, that is, the driving thin film transistor, and converts it into digital sensing data, and stores the digital sensing data for data compensation in the display mode. use. Since the threshold voltage Vth of the second thin film transistor T2, that is, the driving thin film transistor, is compensated in the display mode, the current flowing through the organic light emitting diode D1 is independent of the threshold voltage Vth of the driving thin film transistor, and the threshold voltage Vth of the driving thin film transistor is eliminated.
  • the influence of the light-emitting diode D1 can improve the uniformity of display and improve the luminous efficiency, and the OLED pixel driving circuit of the present invention does not need to additionally set the reference voltage signal as in the prior art, thereby omitting the wiring of the reference voltage signal and reducing the driving IC.
  • the number of channels increases the aperture ratio of the pixel and reduces manufacturing costs.
  • the present invention further provides an OLED display device including the above OLED pixel driving circuit, and the structure and function of the OLED pixel driving circuit are not repeatedly described herein.
  • the OLED pixel driving circuit and the OLED display device of the present invention add a third thin film transistor and a switching switch based on the 2T1C structure, and the first pin of the switching switch is electrically connected to the drain of the third thin film transistor.
  • the second pin is electrically connected to the digital-to-analog converter, and the third pin is electrically connected to the analog-to-digital converter.
  • the switching signal is controlled by the switching signal to turn on the first pin and the second pin to enter the display mode, and the signal is controlled by switching signals.
  • the switch is turned on to switch the first pin and the third pin into the sensing mode, so that the analog-to-digital converter senses the threshold voltage of the second thin film transistor, and is used for data compensation in the display mode after analog-to-digital conversion, thereby having
  • the compensation function can eliminate the influence of the threshold voltage of the driving thin film transistor on the current flowing through the organic light emitting diode, improve the display uniformity, and eliminate the need to additionally set the reference voltage signal as in the prior art, thereby improving the aperture ratio of the pixel and reducing the manufacturing. cost.

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Abstract

一种OLED像素驱动电路及OLED显示装置。该OLED像素驱动电路在2T1C结构的基础上增加第三薄膜晶体管(T3)并设置切换开关(K)，切换开关(K)的第一引脚(K1)电性连接第三薄膜晶体管(T3)的漏极，第二引脚(K2)电性连接数模转换器(DAC)，第三引脚(K3)电性连接模数转换器(ADC)，通过切换信号(Switch)控制切换开关(K)接通第一引脚(K1)与第二引脚(K2)进入显示模式，通过切换信号(Switch)控制切换开关(K)接通第一引脚(K1)与第三引脚(K3)进入感测模式，使得模数转换器(ADC)感测到第二薄膜晶体管(T2)的阈值电压(Vth)，经模数转换后用于显示模式下的数据补偿，不仅具有补偿功能，还能够提高像素的开口率，降低制造成本。

Description

OLED像素驱动电路及OLED显示装置 技术领域
本发明涉及显示技术领域，尤其涉及一种OLED像素驱动电路及OLED显示装置。
背景技术
有机发光二极管(Organic Light Emitting Display，OLED)显示装置具有自发光、驱动电压低、发光效率高、响应时间短、清晰度与对比度高、近180°视角、使用温度范围宽，可实现柔性显示与大面积全色显示等诸多优点，被业界公认为是最有发展潜力的显示装置。
OLED是电流驱动器件，当有电流流经有机发光二极管时，有机发光二极管发光，且发光亮度由流经有机发光二极管自身的电流决定。大部分已有的集成电路(Integrated Circuit，IC)都只传输电压信号，故OLED的像素驱动电路需要完成将电压信号转变为电流信号的任务。传统的OLED像素驱动电路通常为2T1C，即两个薄膜晶体管加一个电容的结构，将电压变换为电流。
如图1所示，传统的用于OLED的2T1C像素驱动电路包括：第一薄膜晶体管T10、第二薄膜晶体管T20、及电容C10，所述第一薄膜晶体管T10为开关薄膜晶体管，所述第二薄膜晶体管T20为驱动薄膜晶体管，所述电容C10为存储电容。具体地，第一薄膜晶体管T10的栅极接入扫描信号Scan，漏极接入数据信号Data，源极与第二薄膜晶体管T20的栅极、及电容C10的一端电性连接；所述第二薄膜晶体管T20的漏极接入电源电压OVDD，源极电性连接有机发光二极管D10的阳极；有机发光二极管D10的阴极接入公共接地电压OVSS；电容C10的一端电性连接第二薄膜晶体管T20的栅极，另一端电性连接第二薄膜晶体管T20的源极。OLED显示时，扫描信号Scan控制第一薄膜晶体管T10导通，数据信号Data经过第一薄膜晶体管T10进入到第二薄膜晶体管T20的栅极及电容C10，然后第一薄膜晶体管T10截止，由于电容C10的存储作用，第二薄膜晶体管T20的栅极电压仍可继续保持数据信号电压，使得第二薄膜晶体管T20处于导通状态，驱动电流通过第二薄膜晶体管T20进入有机发光二极管D10，驱动有机发光二极管D10发光。
根据计算流经驱动薄膜晶体管及有机发光二极管电流的公式：
IOLED＝K×(Vgs-Vth)2
其中：IOLED代表流经驱动薄膜晶体管及有机发光二极管的电流，K为驱动薄膜晶体管的本征导电因子，Vgs代表驱动薄膜晶体管的栅极与源极之间的电压差，Vth代表驱动薄膜晶体管的阈值电压。可见，IOLED的大小与驱动薄膜晶体管的阈值电压Vth有关。
上述传统的OLED像素驱动电路的结构较简单，不具有补偿功能，所以存在很多缺陷，其中比较明显的是：由于薄膜晶体管制造过程中的非均一性，OLED显示装置内每个像素的驱动薄膜晶体管的阈值电压不一致；又因为长时间工作会使驱动薄膜晶体管的材料老化，导致驱动薄膜晶体管的阈值电压漂移，会造成显示不均匀的现象。
图2所示为现有的一种具有补偿功能的3T1C结构的OLED像素驱动电路，在图1所示传统的OLED像素驱动电路的基础上增加了第三薄膜晶体管T30，该第三薄膜晶体管T30的栅极接入感测控制信号Sense，源极电性连接第二薄膜晶体管T20的源极，漏极电性连接模数转换器ADC并接入参考电压信号Vref，数据信号Data由数模转换器DAC提供。该3T1C结构的OLED像素驱动电路能感测到驱动薄膜晶体管的阈值电压Vth，并把Vth值补偿至数据信号Data中，这样能消除驱动薄膜晶体管的阈值电压Vth对流经有机发光二极管的电流IOLED的影响，从而使显示均匀，提高图像质量。但是该3T1C结构的OLED像素驱动电路的缺点有：
1、参考电压信号Vref为各像素提供参考电压，其走线致使像素的开口率降低。
2、参考电压信号Vref的产生使驱动IC的通道数量增加，制造成本增加。
发明内容
本发明的目的在于提供一种OLED像素驱动电路，不仅具有补偿功能，能够消除驱动薄膜晶体管的阈值电压对流经有机发光二极管的电流的影响，提高显示均匀性，还能够提高像素的开口率，降低制造成本。
本发明的另一目的在于提供一种OLED显示装置，其像素驱动电路具有补偿功能，显示均匀性较好，像素开口率较高，制造成本较低。
为实现上述目的，本发明首先提供一种OLED像素驱动电路，包括第一薄膜晶体管、第二薄膜晶体管、第三薄膜晶体管、电容、有机发光二极管、以及设置在驱动IC内的切换开关、数模转换器、与模数转换器；该OLED像素驱动电路的工作状态包括显示模式和感测模式；
所述切换开关受切换信号控制，包括第一引脚、第二引脚、及第三引脚；
所述第一薄膜晶体管的栅极接入扫描信号，漏极接入电源电压，源极与第二薄膜晶体管的栅极、及电容的一端电性连接；所述第二薄膜晶体管的漏极接入电源电压，源极电性连接有机发光二极管的阳极；有机发光二极管的阴极接入公共接地电压；电容的另一端电性连接第二薄膜晶体管的源极；第三薄膜晶体管的栅极在显示模式下接入扫描信号、在感测模式下接入感测控制信号，源极电性连接第二薄膜晶体管的源极，漏极电性连接切换开关的第一引脚；
切换开关的第二引脚电性连接数模转换器，第三引脚电性连接模数转换器；
在显示模式下，切换信号控制切换开关接通第一引脚与第二引脚，数模转换器提供数据信号；在感测模式下，数模转换器先提供一低电位信号，然后切换信号控制切换开关接通第一引脚与第三引脚，使得模数转换器感测到第二薄膜晶体管的阈值电压。
所述数据信号的电位不高于有机发光二极管的阈值电压，所述电源电压高于有机发光二极管的阈值电压与第二薄膜晶体管的阈值电压之和。
所述有机发光二极管的阈值电压为10V。
在显示模式下：所述扫描信号先提供一高电位脉冲，再保持低电位；所述公共接地电压始终为低电位；所述数据信号自扫描信号的高电位脉冲的上升沿开始持续为高电位；
在感测模式下：所述扫描信号先提供一高电位脉冲，再保持低电位；所述感测控制信号先提供一与扫描信号的高电位脉冲同步的高电位脉冲，再保持低电位。
在感测模式下：所述公共接地电压先提供一与感测控制信号的高电位脉冲同步的高电位脉冲，再保持低电位。
本发明还提供一种OLED显示装置，包括OLED像素驱动电路，所述OLED像素驱动电路包括第一薄膜晶体管、第二薄膜晶体管、第三薄膜晶体管、电容、有机发光二极管、以及设置在驱动IC内的切换开关、数模转换器、与模数转换器；该OLED像素驱动电路的工作状态包括显示模式和感测模式；
所述切换开关受切换信号控制，包括第一引脚、第二引脚、及第三引脚；
所述第一薄膜晶体管的栅极接入扫描信号，漏极接入电源电压，源极 与第二薄膜晶体管的栅极、及电容的一端电性连接；所述第二薄膜晶体管的漏极接入电源电压，源极电性连接有机发光二极管的阳极；有机发光二极管的阴极接入公共接地电压；电容的另一端电性连接第二薄膜晶体管的源极；第三薄膜晶体管的栅极在显示模式下接入扫描信号、在感测模式下接入感测控制信号，源极电性连接第二薄膜晶体管的源极，漏极电性连接切换开关的第一引脚；
切换开关的第二引脚电性连接数模转换器，第三引脚电性连接模数转换器；
在显示模式下，切换信号控制切换开关接通第一引脚与第二引脚，数模转换器提供数据信号；在感测模式下，数模转换器先提供一低电位信号，然后切换信号控制切换开关接通第一引脚与第三引脚，使得模数转换器感测到第二薄膜晶体管的阈值电压。
所述数据信号的电位不高于有机发光二极管的阈值电压，所述电源电压高于有机发光二极管的阈值电压与第二薄膜晶体管的阈值电压之和。
所述有机发光二极管的阈值电压为10V。
在显示模式下：所述扫描信号先提供一高电位脉冲，再保持低电位；所述公共接地电压始终为低电位；所述数据信号自扫描信号的高电位脉冲的上升沿开始持续为高电位；
在感测模式下：所述扫描信号先提供一高电位脉冲，再保持低电位；所述感测控制信号先提供一与扫描信号的高电位脉冲同步的高电位脉冲，再保持低电位。
在感测模式下：所述公共接地电压先提供一与感测控制信号的高电位脉冲同步的高电位脉冲，再保持低电位。
本发明还提供一种OLED像素驱动电路，包括第一薄膜晶体管、第二薄膜晶体管、第三薄膜晶体管、电容、有机发光二极管、以及设置在驱动IC内的切换开关、数模转换器、与模数转换器；该OLED像素驱动电路的工作状态包括显示模式和感测模式；
所述切换开关受切换信号控制，包括第一引脚、第二引脚、及第三引脚；
所述第一薄膜晶体管的栅极接入扫描信号，漏极接入电源电压，源极与第二薄膜晶体管的栅极、及电容的一端电性连接；所述第二薄膜晶体管的漏极接入电源电压，源极电性连接有机发光二极管的阳极；有机发光二极管的阴极接入公共接地电压；电容的另一端电性连接第二薄膜晶体管的源极；第三薄膜晶体管的栅极在显示模式下接入扫描信号、在感测模式下 接入感测控制信号，源极电性连接第二薄膜晶体管的源极，漏极电性连接切换开关的第一引脚；
切换开关的第二引脚电性连接数模转换器，第三引脚电性连接模数转换器；
在显示模式下，切换信号控制切换开关接通第一引脚与第二引脚，数模转换器提供数据信号；在感测模式下，数模转换器先提供一低电位信号，然后切换信号控制切换开关接通第一引脚与第三引脚，使得模数转换器感测到第二薄膜晶体管的阈值电压；
其中，所述数据信号的电位不高于有机发光二极管的阈值电压，所述电源电压高于有机发光二极管的阈值电压与第二薄膜晶体管的阈值电压之和；
其中，所述有机发光二极管的阈值电压为10V；
其中，在显示模式下：所述扫描信号先提供一高电位脉冲，再保持低电位；所述公共接地电压始终为低电位；所述数据信号自扫描信号的高电位脉冲的上升沿开始持续为高电位；
在感测模式下：所述扫描信号先提供一高电位脉冲，再保持低电位；所述感测控制信号先提供一与扫描信号的高电位脉冲同步的高电位脉冲，再保持低电位。
本发明的有益效果：本发明提供的一种OLED像素驱动电路及OLED显示装置，在2T1C结构的基础上增加第三薄膜晶体管并设置切换开关，切换开关的第一引脚电性连接第三薄膜晶体管的漏极，第二引脚电性连接数模转换器，第三引脚电性连接模数转换器，通过切换信号控制切换开关接通第一引脚与第二引脚进入显示模式，通过切换信号控制切换开关接通第一引脚与第三引脚进入感测模式，使得模数转换器感测到第二薄膜晶体管的阈值电压，经模数转换后用于显示模式下的数据补偿，从而具有补偿功能，能够消除驱动薄膜晶体管的阈值电压对流经有机发光二极管的电流的影响，提高显示均匀性，并且无需像现有技术那样额外设置参考电压信号，从而还能够提高像素的开口率，降低制造成本。
附图说明
为了能更进一步了解本发明的特征以及技术内容，请参阅以下有关本发明的详细说明与附图，然而附图仅提供参考与说明用，并非用来对本发明加以限制。
附图中，
图1为传统的用于OLED的2T1C像素驱动电路的电路图；
图2为现有的一种具有补偿功能的3T1C结构的OLED像素驱动电路的电路图；
图3为本发明的OLED像素驱动电路的电路图；
图4为本发明的OLED像素驱动电路在显示模式下的电路连接图；
图5为本发明的OLED像素驱动电路在显示模式下的时序图；
图6为本发明的OLED像素驱动电路在感测模式下的电路连接图；
图7为本发明的OLED像素驱动电路在感测模式下的时序图。
具体实施方式
为更进一步阐述本发明所采取的技术手段及其效果，以下结合本发明的优选实施例及其附图进行详细描述。
请同时参阅图3至图7，本发明提供一种OLED像素驱动电路。如图3、图4、及图6所示，本发明的OLED像素驱动电路包括第一薄膜晶体管T1、第二薄膜晶体管T2、第三薄膜晶体管T3、电容C1、有机发光二极管D1、以及设置在驱动IC 10内的切换开关K、数模转换器DAC、与模数转换器ADC。其中，所述第二薄膜晶体管T2为直接对有机发光二极管D1进行驱动的驱动薄膜晶体管。
该OLED像素驱动电路在2T1C结构的基础上增加了第三薄膜晶体管T3并设置切换开关K，且其工作状态包括显示模式和感测模式。
具体地：所述切换开关K受切换信号Switch控制，包括第一引脚K1、第二引脚K2、及第三引脚K3；
所述第一薄膜晶体管T1的栅极接入扫描信号Scan，漏极接入电源电压OVDD，源极与第二薄膜晶体管T2的栅极、及电容C1的一端电性连接；所述第二薄膜晶体管T2的漏极接入电源电压OVDD，源极电性连接有机发光二极管D1的阳极；有机发光二极管D1的阴极接入公共接地电压OVSS；电容C1的另一端电性连接第二薄膜晶体管T2的源极；第三薄膜晶体管T3的栅极在显示模式下接入扫描信号Scan、在感测模式下接入感测控制信号Sense，源极电性连接第二薄膜晶体管T2的源极，漏极电性连接切换开关K的第一引脚K1；
切换开关K的第二引脚K2电性连接数模转换器DAC，第三引脚K3电性连接模数转换器ADC。
所述第一薄膜晶体管T1、第二薄膜晶体管T2、与第三薄膜晶体管T3均为低温多晶硅薄膜晶体管、氧化物半导体薄膜晶体管、或非晶硅薄膜晶 体管。
结合图4与图5，在显示模式下：所述切换信号Switch控制切换开关K接通第一引脚K1与第二引脚K2，数模转换器DAC提供数据信号Data。所述扫描信号Scan先提供一高电位脉冲，使得第一薄膜晶体管T1和第三薄膜晶体管T3均导通。在这一阶段，电源电压OVDD经导通的第一薄膜晶体管T1进入第二薄膜晶体管T2的栅极g，即Vg＝OVDD(Vg表示第二薄膜晶体管T2的栅极g的电位)；所述数据信号Data自扫描信号Scan的高电位脉冲的上升沿开始持续为高电位，数据信号Data经切换开关K的第一引脚K1与第二引脚K2、及导通的第三薄膜晶体管T3写入第二薄膜晶体管T2的源极s，即Vs＝VData(Vs表示第二薄膜晶体管T2的源极s的电位，VData表示数据信号Data的电位)。之后，扫描信号Scan再保持低电位，使得第一薄膜晶体管T1和第三薄膜晶体管T3均截止，依靠电容C1的存储作用，所述有机发光二极管D1发光进行显示。
值得注意的是：在显示模式下，公共接地电压OVSS始终为低电位；所述数据信号Data的电位VData不高于有机发光二极管D1的阈值电压Vth-OLED，即VData≤Vth-OLED，进一步地，所述有机发光二极管D1的阈值电压Vth-OLED约为10V(针对发光层为三叠层或四叠层的有机发光二极管)，这样能够保证在数据信号Data写入过程中第二薄膜晶体管T2的源极s的电位Vs不能使有机发光二极管D1点亮；所述电源电压OVDD高于有机发光二极管D1的阈值电压Vth-OLED与第二薄膜晶体管T2的阈值电压Vth之和，即OVDD＞Vth-OLED+Vth，这样在数据信号Data写入完成后，第二薄膜晶体管T2的栅极g与源极s之间的电压Vgs为：
Vgs＝Vg-Vs＝OVDD-VData＞Vth
保证有机发光二极管D1能正常发光、显示。
结合图6与图7，在感测模式下：所述扫描信号Scan先提供一高电位脉冲使得第一薄膜晶体管T1导通，电源电压OVDD经导通的第一薄膜晶体管T1进入第二薄膜晶体管T2的栅极g，即Vg＝OVDD；所述感测控制信号Sense先提供一与扫描信号Scan的高电位脉冲同步的高电位脉冲使第三薄膜晶体管T3导通，所述切换信号Switch先保持切换开关K接通第一引脚K1与第二引脚K2，数模转换器DAC先提供一低电位信号经切换开关K的第一引脚K1与第二引脚K2、及导通的第三薄膜晶体管T3写入第二薄膜晶体管T2的源极s，同时，所述公共接地电压OVSS先提供一与感测控制信号Sense的高电位脉冲同步的高电位脉冲，保证有机发光二极管D1不能被点亮。紧接着，切换信号Switch控制切换开关K接通第一引脚K1与 第三引脚K3，此时，由于第二薄膜晶体管T2的栅极g的电位为OVDD，而源极s处于较低电位，模数转换器ADC通过导通的第三薄膜晶体管T3、及切换开关K的第一引脚K1与第三引脚K3能够感测到第二薄膜晶体管T2即驱动薄膜晶体管的阈值电压Vth。在这之后，所述扫描信号Scan、感测控制信号Sense、及公共接地电压OVSS均转变为低电位并保持。
模数转换器ADC感测到第二薄膜晶体管T2即驱动薄膜晶体管的阈值电压Vth后转换成数字型的感测数据，并将该数字型的感测数据储存，供显示模式下做数据补偿之用。由于显示模式下，第二薄膜晶体管T2即驱动薄膜晶体管的阈值电压Vth得到补偿，流经有机发光二极管D1的电流便与驱动薄膜晶体管的阈值电压Vth无关，消除了驱动薄膜晶体管的阈值电压Vth对发光二极管D1的影响，能够提高显示的均匀性，提高发光效率，并且本发明的OLED像素驱动电路无需像现有技术那样额外设置参考电压信号，从而省略参考电压信号的走线，减少驱动IC的通道数量，提高像素的开口率，降低制造成本。
基于同一发明构思，本发明还提供一种OLED显示装置，包括上述的OLED像素驱动电路，此处不再对该OLED像素驱动电路的结构及功能进行重复性描述。
综上所述，本发明的OLED像素驱动电路及OLED显示装置，在2T1C结构的基础上增加第三薄膜晶体管并设置切换开关，切换开关的第一引脚电性连接第三薄膜晶体管的漏极，第二引脚电性连接数模转换器，第三引脚电性连接模数转换器，通过切换信号控制切换开关接通第一引脚与第二引脚进入显示模式，通过切换信号控制切换开关接通第一引脚与第三引脚进入感测模式，使得模数转换器感测到第二薄膜晶体管的阈值电压，经模数转换后用于显示模式下的数据补偿，从而具有补偿功能，能够消除驱动薄膜晶体管的阈值电压对流经有机发光二极管的电流的影响，提高显示均匀性，并且无需像现有技术那样额外设置参考电压信号，从而还能够提高像素的开口率，降低制造成本。
以上所述，对于本领域的普通技术人员来说，可以根据本发明的技术方案和技术构思作出其他各种相应的改变和变形，而所有这些改变和变形都应属于本发明后附的权利要求的保护范围。

Claims (12)

  1. 一种OLED像素驱动电路，包括第一薄膜晶体管、第二薄膜晶体管、第三薄膜晶体管、电容、有机发光二极管、以及设置在驱动IC内的切换开关、数模转换器、与模数转换器；该OLED像素驱动电路的工作状态包括显示模式和感测模式；
    所述切换开关受切换信号控制，包括第一引脚、第二引脚、及第三引脚；
    所述第一薄膜晶体管的栅极接入扫描信号，漏极接入电源电压，源极与第二薄膜晶体管的栅极、及电容的一端电性连接；所述第二薄膜晶体管的漏极接入电源电压，源极电性连接有机发光二极管的阳极；有机发光二极管的阴极接入公共接地电压；电容的另一端电性连接第二薄膜晶体管的源极；第三薄膜晶体管的栅极在显示模式下接入扫描信号、在感测模式下接入感测控制信号，源极电性连接第二薄膜晶体管的源极，漏极电性连接切换开关的第一引脚；
    切换开关的第二引脚电性连接数模转换器，第三引脚电性连接模数转换器；
    在显示模式下，切换信号控制切换开关接通第一引脚与第二引脚，数模转换器提供数据信号；在感测模式下，数模转换器先提供一低电位信号，然后切换信号控制切换开关接通第一引脚与第三引脚，使得模数转换器感测到第二薄膜晶体管的阈值电压。
  2. 如权利要求1所述的OLED像素驱动电路，其中，所述数据信号的电位不高于有机发光二极管的阈值电压，所述电源电压高于有机发光二极管的阈值电压与第二薄膜晶体管的阈值电压之和。
  3. 如权利要求2所述的OLED像素驱动电路，其中，所述有机发光二极管的阈值电压为10V。
  4. 如权利要求2所述的OLED像素驱动电路，其中，在显示模式下：所述扫描信号先提供一高电位脉冲，再保持低电位；所述公共接地电压始终为低电位；所述数据信号自扫描信号的高电位脉冲的上升沿开始持续为高电位；
    在感测模式下：所述扫描信号先提供一高电位脉冲，再保持低电位；所述感测控制信号先提供一与扫描信号的高电位脉冲同步的高电位脉冲，再保持低电位。
  5. 如权利要求4所述的OLED像素驱动电路，其中，在感测模式下：所述公共接地电压先提供一与感测控制信号的高电位脉冲同步的高电位脉冲，再保持低电位。
  6. 一种OLED显示装置，包括OLED像素驱动电路，所述OLED像素驱动电路包括第一薄膜晶体管、第二薄膜晶体管、第三薄膜晶体管、电容、有机发光二极管、以及设置在驱动IC内的切换开关、数模转换器、与模数转换器；该OLED像素驱动电路的工作状态包括显示模式和感测模式；
    所述切换开关受切换信号控制，包括第一引脚、第二引脚、及第三引脚；
    所述第一薄膜晶体管的栅极接入扫描信号，漏极接入电源电压，源极与第二薄膜晶体管的栅极、及电容的一端电性连接；所述第二薄膜晶体管的漏极接入电源电压，源极电性连接有机发光二极管的阳极；有机发光二极管的阴极接入公共接地电压；电容的另一端电性连接第二薄膜晶体管的源极；第三薄膜晶体管的栅极在显示模式下接入扫描信号、在感测模式下接入感测控制信号，源极电性连接第二薄膜晶体管的源极，漏极电性连接切换开关的第一引脚；
    切换开关的第二引脚电性连接数模转换器，第三引脚电性连接模数转换器；
    在显示模式下，切换信号控制切换开关接通第一引脚与第二引脚，数模转换器提供数据信号；在感测模式下，数模转换器先提供一低电位信号，然后切换信号控制切换开关接通第一引脚与第三引脚，使得模数转换器感测到第二薄膜晶体管的阈值电压。
  7. 如权利要求6所述的OLED显示装置，其中，所述数据信号的电位不高于有机发光二极管的阈值电压，所述电源电压高于有机发光二极管的阈值电压与第二薄膜晶体管的阈值电压之和。
  8. 如权利要求7所述的OLED显示装置，其中，所述有机发光二极管的阈值电压为10V。
  9. 如权利要求7所述的OLED显示装置，其中，在显示模式下：所述扫描信号先提供一高电位脉冲，再保持低电位；所述公共接地电压始终为低电位；所述数据信号自扫描信号的高电位脉冲的上升沿开始持续为高电位；
    在感测模式下：所述扫描信号先提供一高电位脉冲，再保持低电位；所述感测控制信号先提供一与扫描信号的高电位脉冲同步的高电位脉冲，再保持低电位。
  10. 如权利要求9所述的OLED显示装置，其中，在感测模式下：所述公共接地电压先提供一与感测控制信号的高电位脉冲同步的高电位脉冲，再保持低电位。
  11. 一种OLED像素驱动电路，包括第一薄膜晶体管、第二薄膜晶体管、第三薄膜晶体管、电容、有机发光二极管、以及设置在驱动IC内的切换开关、数模转换器、与模数转换器；该OLED像素驱动电路的工作状态包括显示模式和感测模式；
    所述切换开关受切换信号控制，包括第一引脚、第二引脚、及第三引脚；
    所述第一薄膜晶体管的栅极接入扫描信号，漏极接入电源电压，源极与第二薄膜晶体管的栅极、及电容的一端电性连接；所述第二薄膜晶体管的漏极接入电源电压，源极电性连接有机发光二极管的阳极；有机发光二极管的阴极接入公共接地电压；电容的另一端电性连接第二薄膜晶体管的源极；第三薄膜晶体管的栅极在显示模式下接入扫描信号、在感测模式下接入感测控制信号，源极电性连接第二薄膜晶体管的源极，漏极电性连接切换开关的第一引脚；
    切换开关的第二引脚电性连接数模转换器，第三引脚电性连接模数转换器；
    在显示模式下，切换信号控制切换开关接通第一引脚与第二引脚，数模转换器提供数据信号；在感测模式下，数模转换器先提供一低电位信号，然后切换信号控制切换开关接通第一引脚与第三引脚，使得模数转换器感测到第二薄膜晶体管的阈值电压；
    其中，所述数据信号的电位不高于有机发光二极管的阈值电压，所述电源电压高于有机发光二极管的阈值电压与第二薄膜晶体管的阈值电压之和；
    其中，所述有机发光二极管的阈值电压为10V；
    其中，在显示模式下：所述扫描信号先提供一高电位脉冲，再保持低电位；所述公共接地电压始终为低电位；所述数据信号自扫描信号的高电位脉冲的上升沿开始持续为高电位；
    在感测模式下：所述扫描信号先提供一高电位脉冲，再保持低电位；所述感测控制信号先提供一与扫描信号的高电位脉冲同步的高电位脉冲，再保持低电位。
  12. 如权利要求11所述的OLED像素驱动电路，其中，在感测模式下：所述公共接地电压先提供一与感测控制信号的高电位脉冲同步的高电位脉 冲，再保持低电位。
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