WO2017121124A1 - 一种有机发光二极管的驱动方法、驱动电路和显示装置 - Google Patents

一种有机发光二极管的驱动方法、驱动电路和显示装置 Download PDF

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WO2017121124A1
WO2017121124A1 PCT/CN2016/097265 CN2016097265W WO2017121124A1 WO 2017121124 A1 WO2017121124 A1 WO 2017121124A1 CN 2016097265 W CN2016097265 W CN 2016097265W WO 2017121124 A1 WO2017121124 A1 WO 2017121124A1
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Prior art keywords
voltage
input
reference voltage
reset
driving
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PCT/CN2016/097265
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English (en)
French (fr)
Inventor
刘颖
张成庚
孟昭晖
田宏伟
白娟娟
邵萌
孙文
郑灿
杨华玲
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京东方科技集团股份有限公司
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Priority to US15/521,564 priority Critical patent/US10553153B2/en
Publication of WO2017121124A1 publication Critical patent/WO2017121124A1/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
    • G09G3/3233—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]
    • 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
    • G09G2300/0421—Structural details of the set of electrodes
    • G09G2300/043—Compensation electrodes or other additional electrodes in matrix displays related to distortions or compensation signals, e.g. for modifying TFT threshold voltage in column driver
    • 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
    • G09G2310/00—Command of the display device
    • G09G2310/02—Addressing, scanning or driving the display screen or processing steps related thereto
    • G09G2310/0202—Addressing of scan or signal lines
    • G09G2310/0216—Interleaved control phases for different scan lines in the same sub-field, e.g. initialization, addressing and sustaining in plasma displays that are not simultaneous for all scan lines
    • 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
    • G09G2310/0272—Details of drivers for data electrodes, the drivers communicating data to the pixels by means of a current
    • 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
    • G09G2310/0289—Details of voltage level shifters arranged for use in a driving circuit
    • 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
    • G09G2330/00—Aspects of power supply; Aspects of display protection and defect management
    • G09G2330/02—Details of power systems and of start or stop of display operation
    • G09G2330/026—Arrangements or methods related to booting a display
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2330/00—Aspects of power supply; Aspects of display protection and defect management
    • G09G2330/02—Details of power systems and of start or stop of display operation
    • G09G2330/028—Generation of voltages supplied to electrode drivers in a matrix display other than LCD
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2330/00—Aspects of power supply; Aspects of display protection and defect management
    • G09G2330/08—Fault-tolerant or redundant circuits, or circuits in which repair of defects is prepared
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2330/00—Aspects of power supply; Aspects of display protection and defect management
    • G09G2330/12—Test circuits or failure detection circuits included in a display system, as permanent part thereof

Definitions

  • the present disclosure relates to the field of display, and more particularly to a driving method, a driving circuit, and a display device for an organic light emitting diode.
  • OLED Organic Light Emitting Diode
  • PMOLED Passive Matrix Driving OLED
  • AMOLED Active Matrix Driving OLED
  • FIG. 1 shows an OLED pixel compensation circuit that is common in the prior art.
  • the pixel compensation circuit has a driving tube DTFT whose source is coupled to an EL level of a pixel compensation circuit in a DC-DC control circuit (DC-DC) circuit
  • ELVDD has a gate coupled to the reset voltage input Vinit, a reference voltage input Vref, and a data signal input Vdata, the drain of which is connected to the anode of the OLED display element, and the cathode of the OLED display element is the EL low level ELVSS of the pixel compensation circuit.
  • the SSD circuit detects the EL low level ELVSS of the pixel compensation circuit.
  • a short circuit on the OLED display device for example, when there is component damage or breakdown, a leakage current will be generated on the display element, and the leakage current will be detected by the SSD circuit to turn off the EL high ELVDD of the DC-DC output in time.
  • Figure 2 illustrates a typical DC-DC drive timing of an OLED pixel compensation circuit in the prior art.
  • the reference voltage input Vref rises to the rated reference voltage
  • the reset voltage input Vinit falls to the rated reset voltage
  • the EL high level ELVDD is input
  • the gate-source voltage of the driving transistor DTFT is made.
  • the DTFT is turned on and the drain output is used to drive the current of the display element.
  • the EL low level ELVSS is output 10 ms after the EL high level ELVDD is activated, and the SSD circuit detects at the time when the ELVSS is output, that is, 10 ms after the ELVDD is turned on.
  • an abnormal display may occur at the first frame in which the EL high level ELVDD is activated, and the large current that occurs thereof causes leakage current to be generated.
  • the high current raises the EL low level ELVSS, which is the test point voltage of the SSD circuit, causing the ESD diode of the EL-level ELVSS terminal of the DC-DC circuit to be turned on.
  • the SSD circuit will erroneously detect the EL high ELVDD rise condition as a panel short-circuit fault and turn off the DC-DC circuit output.
  • the display device will not be lit due to the lack of EL voltage, that is, EL high ELVDD and EL low ELVSS.
  • the above-mentioned defects of the pixel compensation circuit of the existing OLED driving circuit may cause the display panel to be turned on and the panel cannot be lit due to DC-DC failure.
  • An object of the present disclosure is to provide an improved driving method, driving circuit, and display device for an organic light emitting diode that can overcome the DC-DC driving timing in the prior art, which may cause a booting screen and due to DC-DC failure.
  • the disadvantage of the display component cannot be lit.
  • an embodiment of the present disclosure provides a driving method of an organic light emitting diode for a pixel compensation circuit having a reference voltage input, a reset voltage input, a data signal input, and a driving display element a driving tube having a control electrode receiving a control signal, a first pole receiving the input signal and a second pole for outputting the output signal, the reference voltage input, the reset voltage input and the data signal input respectively coupled to the driving tube a control electrode, an EL level of the pixel compensation circuit is applied to the first pole of the driving tube, a second pole of the driving tube is coupled to the first pole of the display element, and a second pole voltage of the display element is an EL low voltage of the pixel compensation circuit Flat, wherein the drive tube is turned off by jumping one or more of the reference voltage input, the reset voltage input, and the data signal input before the EL high level starts outputting, and will jump after the EL low level starts outputting One or more of the reference voltage input, reset voltage input, and data signal input are toggle
  • the reference voltage input transitions from zero voltage to the first reference voltage before the EL high level starts outputting, and the reference voltage input jumps from the first reference voltage to the second reference voltage after the EL low level starts outputting, first The reference voltage is higher than the second reference voltage, and the second reference voltage is equal to the rated voltage of the reference voltage input.
  • the reference voltage input jumps from zero voltage to the second reference voltage before the EL high level starts outputting, and then jumps from the second reference voltage to the first reference voltage.
  • the reset voltage input transitions from zero voltage to the first reset voltage before the EL high level starts outputting, and the reset voltage input jumps from the first reset voltage to the second reset voltage after the EL low level starts outputting, first The reset voltage is higher than the second reset voltage, and the second reset voltage is equal to the rated voltage of the reset voltage input.
  • the reset voltage input is maintained at zero voltage before the EL low level starts outputting, and transitions from zero voltage to the second reset voltage after the EL low level starts outputting, and the second reset voltage is equal to the rated voltage of the reset voltage input.
  • the data signal input jumps to the first data signal before the EL high level starts outputting, and the data signal input jumps from the first data signal to the second data signal after the EL low level starts outputting.
  • an embodiment of the present disclosure provides a driving circuit of an organic light emitting diode, including a DC-DC control circuit and a pixel compensation circuit, the DC-DC control circuit is connected to the pixel compensation circuit, and the pixel compensation circuit has a reference voltage input, a reset voltage input, a data signal input, and a drive tube for driving the display element, the drive tube having a control electrode receiving the control signal, a first pole receiving the input signal, and a second pole for outputting the output signal,
  • the reference voltage input, the reset voltage input and the data signal input are respectively coupled to the control pole of the driving tube, the EL level of the pixel compensation circuit is applied to the first pole of the driving tube, and the second pole of the driving tube is coupled to the display element
  • the second pole voltage of the display component is an EL low level of the pixel compensation circuit
  • the DC-DC control circuit includes a voltage jump unit configured to jump before starting output at the EL high level One of variable reference voltage input, reset voltage input, and
  • the voltage hopping unit comprises a first boosting unit and a first step-down unit, the first boosting unit being configured such that the reference voltage input transitions from zero voltage to the first reference voltage before the EL high level starts outputting,
  • the first buck unit is configured such that the reference voltage input transitions from the first reference voltage to the second reference voltage after the EL low level starts outputting, the first reference voltage is higher than the second reference voltage, and the second reference voltage is equal to the reference The rated voltage of the voltage input.
  • the first boosting unit is configured to cause the reference voltage input to jump from zero voltage to the second reference voltage before the EL high level starts outputting, and then jump from the second reference voltage to the first reference voltage.
  • the voltage hopping unit comprises a second boosting unit and a second step-down unit, the second boosting unit being configured such that the reset voltage input transitions from zero voltage to the first reset voltage before the EL high level starts outputting,
  • the second buck unit is configured such that the reset voltage input transitions from the first reset voltage to the second reset voltage after the EL low level starts outputting, the first reset voltage is higher than the second reset voltage, and the second reset voltage is equal to the reset The rated voltage of the voltage input.
  • the voltage hopping unit comprises a second step-down unit, the reset voltage input is maintained at zero voltage before the EL low level starts outputting, and the second step-down unit is configured such that the reset voltage input is after the EL low level starts outputting The zero voltage jumps to the second reset voltage, and the second reset voltage is equal to the rated voltage of the reset voltage input.
  • the voltage hopping unit comprises a third boosting unit and a third step-down unit, the third boosting unit being configured to cause the data signal input to jump from zero voltage to the first data signal before the EL high level starts outputting,
  • the third buck unit is configured to The data signal input transitions from the first data signal to the second data signal after the EL low level begins to output.
  • the voltage hopping unit is preferably integrated into the IC.
  • an embodiment of the present disclosure provides an organic light emitting diode display device including the driving circuit as described above.
  • the driving method, the driving circuit, and the display device of the organic light emitting diode provided by the present disclosure jump one of a reference voltage input, a reset voltage input, and a data signal input before the EL high level starts outputting or a plurality of to control the gate voltage of the driving transistor DTFT to turn off the driving transistor DTFT and jump one or more of the jumped reference voltage input, the reset voltage input, and the data signal input after the EL low level starts outputting Changing to control the gate voltage of the driving transistor DTFT to turn on the driving transistor DTFT, avoiding the leakage current caused by the abnormal rise of the EL high ELVDD in the SSD circuit detecting panel short-circuit fault, which negatively affects the detection voltage, so that the SSD circuit can be completed normally Detecting and preventing leakage current drives the display element to produce a splash screen.
  • the normal driving of the display device during the power-on process of the pixel compensation circuit can be realized, the display effect of the OLED display device can be improved, and the detection efficiency of the SSD circuit can be improved, the startup splash screen can be avoided, and the display cannot be lit due to DC-DC failure.
  • FIG. 1 shows a schematic diagram of a pixel compensation circuit in the prior art.
  • FIG. 2 shows a DC-DC drive timing diagram of a pixel compensation circuit in the prior art.
  • FIG. 3 illustrates a DC-DC drive timing diagram of an improved pixel compensation circuit in accordance with an embodiment of the present disclosure.
  • FIG. 4 shows a circuit diagram of a buck unit employed in an embodiment of the present disclosure.
  • FIG. 5 shows a circuit diagram of a boosting unit employed in an embodiment of the present disclosure.
  • FIG. 6 shows a DC-DC drive timing diagram of another improved pixel compensation circuit of an embodiment of the present disclosure.
  • FIG. 7 shows a DC-DC drive timing diagram of yet another improved pixel compensation circuit of an embodiment of the present disclosure.
  • the switching elements employed are exemplified by P-type field effect (MOS) transistors. It is also possible to implement the function of the switching element by using an N-type field effect transistor and a P-type or N-type bipolar (BJT) transistor. Since the source and drain (emitter and collector) of the transistor are symmetrical, and the conduction currents between the source and the drain (emitter and collector) of the P-type transistor and the N-type transistor are opposite, In an embodiment of the present disclosure, the controlled intermediate terminal of the transistor is a gate, the signal input terminal is a source, and the signal output terminal is a drain.
  • MOS P-type field effect
  • BJT bipolar
  • any controlled switching device having a strobe signal input can be used to implement the function of the switching element, and the controlled intermediate terminal of the switching device for receiving control signals (eg, for turning the controlled switching device on and off)
  • the signal input is called the first pole and the signal output is called the second pole.
  • the transistors employed in the embodiments of the present disclosure are primarily switching transistors.
  • the improved driving method, driving circuit and display device for an organic light emitting diode of the present disclosure are mainly used for an OLED display element, particularly an AMOLED display element.
  • FIG. 1 shows a pixel compensation circuit in the prior art.
  • the pixel compensation circuit includes a driving transistor DTFT and first to sixth switching elements T1-T6, and a reference voltage input Vref, a reset voltage input Vinit, and a data signal input Vdata for driving The EL level ELVDD and the EL level ELVSS of the pixel compensation circuit of the display element.
  • the gate of the first switching element T1 is coupled to the REST signal input, the source thereof is coupled to the EL high level ELVDD from the DC-DC input for driving the display element, and the drain thereof is coupled to the node 1;
  • the gate of the second switching element T2 is also coupled to the REST signal input, the source thereof is coupled to the reset voltage input Vinit, and the drain thereof is coupled to the gate of the driving transistor DTFT via the node 2;
  • the gate of the third switching element T3 is coupled to the GATE signal input, the source thereof is coupled to the data signal input Vdata, and the drain thereof is coupled to the node 1;
  • the gate of the fourth switching element T4 is coupled to the GATE signal input, the source thereof is coupled to the drain of the driving transistor DTFT, and the drain thereof is coupled to the node 2;
  • the gate of the fifth switching element T5 is coupled to the EM signal input, the source of which is coupled to the reference voltage input Vref, and the drain thereof passes through the node 1 and the drain of the first switching element T1 and the drain of the third switching element T3, respectively.
  • the gate of the sixth switching element T6 is coupled to the EM signal input, the source of which is coupled to the drain of the driving transistor DTFT and the source of the fourth switching element T4, and the drain of which is coupled to the OLED or AMOLED display element positive electrode;
  • the gate of the driving transistor DTFT is respectively coupled to the drain of the fourth switching element T4, the drain of the second switching element T2, and the storage capacitor C via the node 2, and the source thereof is also coupled to the EL high level ELVDD, and the drain thereof Coupling the source of the sixth switching element T6;
  • a display element having a positive electrode coupled to a drain of the sixth switching element and a negative electrode being an EL low level ELVSS of the pixel compensation circuit;
  • a storage capacitor C is coupled between node 1 and node 2.
  • the gate of the driving transistor DTFT is coupled to the reference voltage input Vref through the storage capacitor C and the fifth switching element T5, respectively, and the data signal input Vdata is coupled through the storage capacitor C and the third switching element T3, and the second switching element is passed through the second switching element.
  • T2 is coupled to the reset voltage input Vinit.
  • the working process mainly has three working phases of a reset phase, a data writing phase and a lighting phase.
  • the Rest phase is used to reset the gate voltage of the drive tube in preparation for displaying the next frame image on the display panel.
  • the Rest signal is placed at a low level, at which time the first and second switching elements T1, T2 are turned on.
  • the rated reset voltage input Vinit2 is input to the gate of the driving transistor DTFT via the node 2, thereby lowering the gate voltage Vgate of the DTFT to ensure that the Vdata voltage can be normally written and writing the voltage of the node 1 to the EL high voltage.
  • Flat ELVDD Flat ELVDD.
  • the data write phase is used to write a control sequence to display the pattern on the panel.
  • the gate of the DTFT is placed at a low level, and at this time, the third and fourth switching elements T3, T4 are turned on.
  • the data signal is then input to Vdata input node 1 to write the control sequence.
  • the voltage of the node 2 is ELVDD-
  • the illuminating (EM) stage is used to drive the display element to illuminate according to a control sequence.
  • the EM signal is placed at a low level, at which time the fifth and sixth switching elements T5, T6 are turned on.
  • the nominal reference voltage input Vref2 is then applied to node 1, and since the voltage across capacitor C cannot be transient, the voltage at node 2 becomes ELVDD-
  • ⁇ is the electron mobility
  • C OX is the oxide capacitance per unit area
  • W is the thickness of the channel depletion layer
  • L is the channel length
  • V GS is the gate-source voltage of the switching element
  • V th is the threshold voltage of the transistor .
  • V GS >V th the driving transistor DTFT is turned off, the large current of the EL high ELVDD input does not flow to the display element, and the panel will normally emit light.
  • V GS -V th ELVDD1-
  • ELVDD is no longer constant and therefore cannot be offset by operation.
  • the difference between ELVDD2 and ELVDD1 will cause the current I to become larger. Since V GS ⁇ V th , the driving transistor DTFT is turned on, thereby generating a large current between the EL high level ELVDD and the EL low level ELVSS.
  • the key is that the large current cannot be made when the EL high level ELVDD abnormally becomes high.
  • the voltage of the EL low level ELVSS is not affected, that is, the driving voltage of the display element and the detection voltage of the SSD circuit are not affected.
  • the turn-on and turn-off of the driver DTFT depends on the gate-source voltage V GS of the DTFT.
  • V GS can be controlled by changing the gate voltage of the DTFT.
  • the gate voltage of the driving transistor DTFT can be controlled by one or more of the reference voltage input Vref, the reset voltage input Vinit, and the data signal input Vdata. Therefore, one or more of Vref, Vinit, and Vdata can be jumped to raise the gate voltage of the driving transistor DTFT before the EL high ELVDD is activated, so that sufficient shutdown can be provided even if ELVDD abnormally rises.
  • the gate-to-source voltage V GS of the DTFT is again hopped again by one or more of the hopped Vref, Vinit, and Vdata after the EL low level begins to output to resume normal display of the display element.
  • FIG. 3 shows the DC-DC drive timing after the DC-DC drive timing of the existing pixel compensation circuit is improved.
  • the reference voltage input Vref is raised from zero voltage to a reference voltage Vref1 higher than the rated reference voltage Vref2 before the EL high level ELVDD starts outputting, and the reference voltage input Vref is lowered from Vref1 after the EL low level ELVSS starts outputting Rated reference voltage Vref2.
  • the reset voltage input Vinit is reduced from zero voltage to a reset voltage Vinit1 higher than the rated reset voltage Vinit2 before the EL high ELVDD starts outputting, and the reset voltage input Vinit is lowered from Vinit1 to the rated value after the EL low level ELVSS starts outputting.
  • Reset voltage Vinit2 Reset voltage Vinit2.
  • the selection of the reference voltage Vref1 and the reset voltage Vinit is such that the gate voltage of the driving transistor DTFT is always controlled during the period from the EL high ELVDD start output to the EL low level ELVSS start output, that is, the time during which the SSD circuit is detected.
  • Broken DTFT For example, when the EL high level ELVDD suddenly jumps, the reference voltage Vref1 and the reset voltage Vinit1 cause the gate-source voltage V GS of the driving transistor DTFT to be greater than its threshold voltage V th , that is, satisfy Vinit1+Vref1-ELVDD1>V. Th to ensure that the drive transistor DTFT is turned off.
  • the pixel compensation circuit using the improved DC-DC drive timing drives the state of the display element during the working phase to become:
  • the gate Gate signal of the driving transistor DTFT is placed at a low level, and the third and fourth switching elements T3, T4 are turned on.
  • the data signal input Vdata is then applied to node 1, and since the voltage across capacitor C cannot be transient, the node voltage of node 2 is Vdata+Vinit1-ELVDD.
  • ELVDD is zero, the voltage of node 2 is Vdata+Vinit1;
  • the EM signal is placed at a low level, and the fifth and sixth switching elements T5, T6 are turned on. Then, the reference voltage Vref1 is applied to the node 1. Since the voltage across the capacitor C cannot be transient, the voltage of the node 2 is Vdata+Vinit1+Vref1-Vdata, and the voltage of the node 2 after eliminating the Vdata term is Vint1+Vref1.
  • V GS Vinit1 + Vref1- ELVDD1> V th, the drive tube DTFT off, operating normally.
  • the pixel voltage of the pixel compensation circuit according to the above-described improved DC-DC driving timing in the working phase in which the node 1 and the node 2 are displaying the image of the first frame is as shown in Table 2.
  • Table 2 improves the node voltages of nodes 1 and 2 under the drive timing
  • the voltage jump of the reference voltage input Vref and the reset voltage input Vinit in the improved DC-DC drive timing described above can be implemented by a voltage jump unit.
  • the voltage hopping unit can be realized by a buck unit as shown in FIG. 4 and a boosting unit as shown in FIG. 5.
  • the reference voltage input Vref, the reset voltage input Vinit, and the data signal input Vdata are respectively used as the input voltage Vin of the buck unit or the boost unit, and the buck unit or the boost unit controls the output voltage Vout of the output by the pulse (PLUSE) as a jump.
  • the subsequent reference voltage input Vref, the reset voltage input Vinit, and the data signal input Vdata is used.
  • the switching element uses a MOS tube, and a bipolar transistor or other switching device having a strobe signal input can also be used.
  • the buck unit shown in FIG. 4 includes a MOS transistor M1, an inductor L1, a diode D1, a capacitor C1, and an input voltage Vin and an output voltage Vout.
  • the voltage of the inductor during one switching cycle is:
  • V L is the inductor voltage
  • V M is the source-drain voltage of the MOS transistor M1
  • V D is the diode voltage
  • the boosting unit shown in FIG. 5 includes a MOS transistor M2, an inductor L2, a diode D2, a capacitor C2, and an input voltage Vin and an output voltage Vout.
  • PWM Pulse Width Modulation
  • the buck and boost units described above can also be integrated into a IC integrated circuit with registers as a voltage hopping unit. By modifying the register settings to output improved drive timing, the IC can be used to complete the DC-DC drive of the display panel.
  • the IC is for example but not limited to using TPS 65633 or DW 8722.
  • the above describes an improved DC-DC driving method, control circuit, and display device that employ a reference voltage input Vref and a reset voltage input Vinit to simultaneously jump.
  • a reference voltage input Vref and a reset voltage input Vinit to simultaneously jump.
  • the drive transistor DTFT is kept off during the start of the output.
  • the drive timing shown in FIG. 6 describes an embodiment of the present disclosure that individually transitions the reset voltage input Vinit.
  • the reset voltage input Vref maintains zero voltage before the EL low level ELVSS starts outputting, and decreases from zero voltage to the rated reset after the EL low level ELVSS starts outputting Voltage.
  • Figure 7 shows the DC-DC drive timing of a reference voltage input Vref with multiple transitions. Without changing the reset voltage input Vinit, the reference voltage input Vref rises to the rated reference voltage before the EL high ELVDD starts to output, and then rises to a reference voltage higher than the rated reference voltage, for example, in a stepwise manner, and then EL high ELVDD starts output. After the ELVSS begins to output, the reference voltage input Vref is reduced to the nominal reference voltage.
  • the driving circuit and the display device can improve the display effect of the OLED or AMOLED display device, improve the detection efficiency of the SSD circuit, and avoid the phenomenon that the booting screen and the DC-DC fail to illuminate the display component, thereby effectively reducing the display device and the driving circuit. Power and life loss.

Abstract

一种有机发光二极管的驱动方法、驱动电路和显示装置，其中通过跳变参考电压输入(Vref)、复位电压输入(Vinit)和数据信号输入(Vdata)中的一个或多个以在像素补偿电路的EL高电平(ELVDD)启动输出之前到EL低电平(ELVSS)启动输出之后的时间期间关断用于驱动显示元件的驱动管(DTFT)，以克服开机闪屏和直流-直流驱动失效问题。

Description

一种有机发光二极管的驱动方法、驱动电路和显示装置
相关申请的交叉引用
本申请要求于2016年01月11日递交的中国专利申请第201610014133.3号的优先权，在此全文引用上述中国专利申请公开的内容以作为本申请的一部分。
技术领域
本公开涉及显示领域，尤其涉及用于有机发光二极管的驱动方法、驱动电路和显示装置。
背景技术
有机发光二极管(Organic Light Emitting Diode，OLED)作为一种电流型发光元件，因其轻薄、反应速度快、对比度高等特点已成为目前显示设备中的主流显示元件。按照驱动方式，PMOLED(Passive Matrix Driving OLED，无源矩阵驱动有机发光二极管)和AMOLED(Active Matrix Driving OLED，有源矩阵驱动有机发光二极管),AMOLED具有驱动时间短，功耗更低的优点。
在OLED像素补偿电路的正常工作阶段之前，首先要对像素补偿电路开机上电并使用SSD(开机短路检测)电路进行面板短路检测。图1示出在现有技术中常见的OLED像素补偿电路。该像素补偿电路具有驱动管DTFT，其源极耦接到直流-直流控制(DC-DC)电路中的像素补偿电路的EL高电平 ELVDD，其栅极耦接复位电压输入Vinit、参考电压输入Vref和数据信号输入Vdata，其漏极连接OLED显示元件的阳极，OLED显示元件的阴极为像素补偿电路的EL低电平ELVSS。SSD电路检测像素补偿电路的EL低电平ELVSS。当OLED显示装置上存在短路时，例如存在元件损坏或击穿时，在显示元件上将产生漏电流，该漏电流会被SSD电路检测到从而及时关断DC-DC输出的EL高电平ELVDD。图2示出在现有技术中的OLED像素补偿电路的典型DC-DC驱动时序。在像素补偿电路的上电过程中，首先参考电压输入Vref上升到额定参考电压，复位电压输入Vinit下降到额定复位电压，随后输入EL高电平ELVDD，驱动管DTFT的栅极-源极电压使DTFT导通，漏极输出用于驱动显示元件的电流。
现有的用于显示装置的像素补偿电路的驱动时序中，EL低电平ELVSS在EL高电平ELVDD启动后10ms输出，SSD电路在ELVSS输出的时刻，即ELVDD启动后10ms，进行检测。但是，在这10ms期间，可能在EL高电平ELVDD启动的第一帧发生异常显示，其出现的大电流导致产生漏电流。大电流抬高EL低电平ELVSS，即SSD电路的测试点电压，导致DC-DC电路EL低电平ELVSS端的ESD二极管导通。例如，SSD电路检测到的EL低电平ELVSS电压为700mV，大于阈值电压200mV，则SSD电路将错误地将该EL高电平ELVDD抬高情况检测为面板短路故障而关断DC-DC电路输出，显示装置将因为缺少EL电压，即EL高电平ELVDD和EL低电平ELVSS而无法点亮。现有OLED驱动电路的像素补偿电路的上述缺陷会造成显示面板开机闪屏和由于DC-DC失效而面板无法点亮的问题。
发明内容
本公开的目的之一是提供一种改进的有机发光二极管的驱动方法、驱动电路和显示装置，其能够克服现有技术中的DC-DC驱动时序可能导致开机闪屏和由于DC-DC失效而无法点亮显示元件的缺点。
根据本公开的一方面，本公开的实施例提供一种有机发光二极管的驱动方法，用于像素补偿电路，像素补偿电路具有参考电压输入、复位电压输入、数据信号输入、以及用于驱动显示元件的驱动管，驱动管具有接收控制信号的控制极，接收输入信号的第一极和用于输出输出信号的第二极，参考电压输入、复位电压输入和数据信号输入分别耦接到驱动管的控制极，像素补偿电路的EL高电平施加到驱动管的第一极，驱动管的第二极耦接显示元件的第一极，显示元件的第二极电压为像素补偿电路的EL低电平，其中，通过在EL高电平开始输出之前跳变参考电压输入、复位电压输入、数据信号输入中的一个或多个来关断驱动管并且在EL低电平开始输出之后将所跳变的参考电压输入、复位电压输入、数据信号输入中的一个或多个再次跳变来开启驱动管。
其中，参考电压输入在EL高电平开始输出之前从零电压跳变到第一参考电压，参考电压输入在EL低电平开始输出之后从第一参考电压跳变到第二参考电压，第一参考电压高于第二参考电压，第二参考电压等于参考电压输入的额定电压。
其中，参考电压输入在EL高电平开始输出之前先从零电压跳变到第二参考电压，再从第二参考电压跳变到第一参考电压。
其中，复位电压输入在EL高电平开始输出之前从零电压跳变到第一复位电压，复位电压输入在EL低电平开始输出之后从第一复位电压跳变到第二复位电压，第一复位电压高于第二复位电压，第二复位电压等于复位电压输入的额定电压。
其中，复位电压输入在EL低电平开始输出之前保持为零电压，在EL低电平开始输出之后从零电压跳变到第二复位电压，第二复位电压等于复位电压输入的额定电压。
其中，数据信号输入在EL高电平开始输出之前跳变到第一数据信号，数据信号输入在EL低电平开始输出之后从第一数据信号跳变到第二数据信号。
根据本公开的另一方面，本公开的实施例提供一种有机发光二极管的驱动电路，包括直流-直流控制电路和像素补偿电路，直流-直流控制电路与像素补偿电路相连接，像素补偿电路具有参考电压输入、复位电压输入、数据信号输入、以及用于驱动显示元件的驱动管，驱动管具有接收控制信号的控制极，接收输入信号的第一极和用于输出输出信号的第二极，参考电压输入、复位电压输入和数据信号输入分别耦接到驱动管的控制极，像素补偿电路的EL高电平施加到驱动管的第一极，驱动管的第二极耦接显示元件的第一极，显示元件的第二极电压为像素补偿电路的EL低电平，其中，直流-直流控制电路包括电压跳变单元，电压跳变单元被配置为通过在EL高电平开始输出之前跳变参考电压输入、复位电压输入、数据信号输入中的一 个或多个来关断驱动管并且在EL低电平开始输出之后将所跳变的参考电压输入、复位电压输入、数据信号输入中的一个或多个再次跳变来开启驱动管。
其中，电压跳变单元包括第一升压单元和第一降压单元，第一升压单元被配置为使得参考电压输入在EL高电平开始输出之前从零电压跳变到第一参考电压，第一降压单元被配置为使得参考电压输入在EL低电平开始输出之后从第一参考电压跳变到第二参考电压，第一参考电压高于第二参考电压，第二参考电压等于参考电压输入的额定电压。
其中，第一升压单元被配置为使得参考电压输入在EL高电平开始输出之前先从零电压跳变到第二参考电压，再从第二参考电压跳变到第一参考电压。
其中，电压跳变单元包括第二升压单元和第二降压单元，第二升压单元被配置为使得复位电压输入在EL高电平开始输出之前从零电压跳变到第一复位电压，第二降压单元被配置为使得复位电压输入在EL低电平开始输出之后从第一复位电压跳变到第二复位电压，第一复位电压高于第二复位电压，第二复位电压等于复位电压输入的额定电压。
其中，电压跳变单元包括第二降压单元，复位电压输入在EL低电平开始输出之前保持为零电压，第二降压单元被配置为使得复位电压输入在EL低电平开始输出之后从零电压跳变到第二复位电压，第二复位电压等于复位电压输入的额定电压。
其中，电压跳变单元包括第三升压单元和第三降压单元，第三升压单元被配置为使得数据信号输入在EL高电平开始输出之前从零电压跳变到第一数据信号，第三降压单元被配置为使 得数据信号输入在EL低电平开始输出之后从第一数据信号跳变到第二数据信号。
其中，电压跳变单元优选集成到IC中。
根据本公开的又一方面，本公开的实施例提供一种有机发光二极管显示装置，其包括如上所述的驱动电路。
与现有技术相比，本公开提供的有机发光二极管的驱动方法、驱动电路和显示装置，通过在EL高电平开始输出之前跳变参考电压输入、复位电压输入和数据信号输入中的一个或多个来控制驱动管DTFT的控制极电压从而关断驱动管DTFT并且在EL低电平开始输出之后将所跳变的参考电压输入、复位电压输入、数据信号输入中的一个或多个再次跳变来控制驱动管DTFT的控制极电压从而开启驱动管DTFT，在SSD电路检测面板短路故障时避免EL高电平ELVDD异常升高导致的漏电流对检测电压造成负面影响，使SSD电路能够正常完成检测并且防止漏电流驱动显示元件产生闪屏。因此，可以实现像素补偿电路在上电过程中对显示装置的正常驱动，改善OLED显示装置的显示效果，同时提高SSD电路的检测效率，避免开机闪屏和由于DC-DC失效而无法点亮显示元件的现象。
附图说明
为使本公开的目的、技术方案和优点更加清楚，下面将结合附图对本公开的实施方式作进一步的详细描述。在附图中，相同的标记表示相同的元件。本领域技术人员将理解，附图中描述的具体实施方式仅作为本公开技术方案的示例，而不是对其的限制。在附图中：
图1示出现有技术中的像素补偿电路的示意图。
图2示出现有技术中的像素补偿电路的DC-DC驱动时序图。
图3示出根据本公开的实施例的改进像素补偿电路的DC-DC驱动时序图。
图4示出本公开的实施例所采用的降压单元的电路图。
图5示出本公开的实施例所采用的升压单元的电路图。
图6示出本公开的实施例的另一种改进像素补偿电路的DC-DC驱动时序图。
图7示出本公开的实施例的又一种改进像素补偿电路的DC-DC驱动时序图。
具体实施方式
下面将结合本公开的附图，对本公开的实施例中的技术方案进行清楚、完整地描述。应理解的是，本公开的具体实施例仅是示意性的，而不作为对本公开保护范围的任何限制。
本领域技术人员将理解，在此所使用的术语仅是为了描述特定实施例的目的，并不旨在限制本公开。如在此所使用的，单数形式“一个”、“一”和“该”旨在也包括复数形式，除非在其它情况下明确陈述。应进一步理解，当术语“包括”、“包含”、“包括了”和/或“包含了”在本说明书中使用时，指存在所述元件和/或部件，但不排除存在或附加一个或多个其它元件、部件和/或它们的组合。
除非另外定义，否则在此使用的所有术语(包括技术和科学术语)具有与本公开主题所属的领域的技术人员所通常理解 的相同含义。进一步将理解的是，诸如在通常使用的词典中定义的那些的术语应解释为具有与说明书上下文和相关技术中它们的含义一致的含义，并且将不以理想化或过于正式的形式来解释，除非在此另外明确定义。在本公开中使用的“第一”、“第二”、“第三”、“第四”以及类似术语并不表示任何顺序、数量或者重要性，而只是用来区分不同的组成部分。如在此所使用的，将两个或更多部分“连接”或“耦接”到一起的陈述应指该部分直接结合到一起或通过一个或多个中间部件结合。
在本公开的实施例中，所采用的开关元件以P型场效应(MOS)管示例。同样可以采用N型场效应管，以及P型或N型双极性(BJT)晶体管实现开关元件的功能。由于晶体管的源极和漏极(发射极和集电极)是对称的，并且P型晶体管和N型晶体管的源极和漏极(发射极和集电极)之间的导通电流方向相反，因此在本公开的实施例中，规定晶体管的受控中间端为栅极，信号输入端为源极，信号输出端为漏极。进一步，可以采用具有选通信号输入的任何受控开关器件来实现开关元件的功能，将用于接收控制信号(例如用于开启和关断受控开关器件)的开关器件的受控中间端称为控制极，信号输入端称为第一极，信号输出端称为第二极。本公开的实施例中所采用的晶体管主要是开关晶体管。本公开的用于有机发光二极管的改进驱动方法、驱动电路和显示装置主要用于OLED显示元件，特别是AMOLED显示元件。
图1示出现有技术中的一种像素补偿电路。该像素补偿电路包括驱动管DTFT和第一至第六开关元件T1-T6，以及参考电压输入Vref，复位电压输入Vinit，数据信号输入Vdata，用于驱 动显示元件的像素补偿电路的EL高电平ELVDD和EL低电平ELVSS。
其中：
第一开关元件T1的栅极耦接到REST信号输入，其源极耦接到来自DC-DC输入的用于驱动显示元件的EL高电平ELVDD，而其漏极耦接到节点1；
第二开关元件T2的栅极同样耦接到REST信号输入，其源极耦接复位电压输入Vinit，而其漏极经由节点2耦接到驱动管DTFT的栅极；
第三开关元件T3的栅极耦接到GATE信号输入，其源极耦接数据信号输入Vdata，而其漏极耦接到节点1；
第四开关元件T4的栅极耦接到GATE信号输入，其源极耦接驱动管DTFT的漏极，而其漏极耦接到节点2；
第五开关元件T5的栅极耦接到EM信号输入，其源极耦接参考电压输入Vref，而其漏极通过节点1分别与第一开关元件T1的漏极、第三开关元件T3的漏极耦接；
第六开关元件T6的栅极耦接到EM信号输入，其源极耦接到驱动管DTFT的漏极以及第四开关元件T4的源极，而其漏极耦接到OLED或AMOLED显示元件的正极；
驱动管DTFT的栅极分别经由节点2耦接第四开关元件T4的漏极、第二开关元件T2的漏极和存储电容器C，其源极同样耦接到EL高电平ELVDD，其漏极耦接第六开关元件T6的源极；
显示元件，其正极耦接到第六开关元件的漏极，而负极为像素补偿电路的EL低电平ELVSS；以及
存储电容器C，其耦接在节点1与节点2之间。
由此可知，驱动管DTFT的栅极分别通过存储电容器C和第五开关元件T5耦接参考电压输入Vref，通过存储电容器C和第三开关元件T3耦接数据信号输入Vdata，通过第二开关元件T2耦接复位电压输入Vinit。
下面将根据图1和图2描述像素补偿电路驱动显示元件的工作过程。该工作过程主要具有复位阶段、数据写入阶段和发光阶段三个工作阶段。
复位(Rest)阶段用于复位驱动管的栅极电压，以准备在显示面板上显示下一帧图像。首先将Rest信号置于低电平，此时第一和第二开关元件T1、T2导通。将额定复位电压输入Vinit2经由节点2输入驱动管DTFT的栅极，从而将DTFT的栅极电压Vgate置于低电平，以保证Vdata电压可以正常写入并且将节点1的电压写入EL高电平ELVDD。
数据写入(Gate)阶段用于写入控制序列以在面板上显示图案。首先将DTFT的栅极置于低电平，此时第三和第四开关元件T3、T4导通。然后将数据信号输入Vdata输入节点1以写入控制序列。而节点2的电压为ELVDD-|Vth|，其中Vth为开关元件的阈值电压。当ELVDD为零时，节点2的电压为-|Vth|。
发光(EM)阶段用于根据控制序列驱动显示元件发光。首先将EM信号置于低电平，此时第五和第六开关元件T5、T6导通。然后将额定参考电压输入Vref2施加到节点1，由于电容器C两端电压不能瞬变，因此节点2的电压变为ELVDD-|Vth|+Vref2-Vdata。
根据上述分析，在不同阶段周期中的节点1和2的电压如表1所示。
表1现有驱动时序下的节点1和2的电压
周期 节点1的电压 节点2的电压
Rest开启 ELVDD Vinit2
Gate开启 Vdata -|Vth|
Em开启 Vref2 -|Vth|+Vref2-Vdata
现在根据晶体管的导通特性以及图2中所示的现有技术DC-DC驱动时序图来详细分析像素补偿电路在正常和异常情况下的工作状态。
开关元件电流公式：
Figure PCTCN2016097265-appb-000001
其中μ为电子迁移率，COX为单位面积氧化层电容，W为沟道耗尽层厚度，L为沟道长度，VGS为开关元件的栅极-源极电压，Vth为晶体管阈值电压。
在正常情况下，对于驱动管DTFT：
VGS–Vth＝
ELVDD-|Vth|+Vref–Vdata–ELVDD–Vth＝Vref–Vdata>0
Figure PCTCN2016097265-appb-000002
由于VGS>Vth，因此驱动管DTFT截止，EL高电平ELVDD输入的大电流不会流到显示元件，面板将正常发光。
然而在异常情况下，当EL高电平ELVDD突然启动，从原ELVDD1上升到ELVDD2，例如由0V上升到4.6V时，对于驱动管DTFT：
VGS-Vth＝ELVDD1-|Vth|+Vref–Vdata-ELVDD2-Vth
          ＝ELVDD1+Vref–Vdata-ELVDD2<0
Figure PCTCN2016097265-appb-000003
其中ELVDD不再恒定，因此无法通过运算抵消。ELVDD2与ELVDD1的差将造成电流I变大。由于VGS<Vth，驱动管DTFT导通，从而在EL高电平ELVDD到EL低电平ELVSS之间产生大电流。该大电流会出现两个问题：1)导致显示面板的第一帧画面显示异常而发生闪屏现象；2)EL低电平ELVSS端的电压过高，使得DC-DC驱动电路中的SSD电路在EL高电平ELVDD启动10ms后进行面板短路检测时检测到高于阈值电压的EL低电平ELVSS端电压，因此错误地将该状态识别为面板短路进而错误地关断DC-DC输入使其无法启动而失效，造成显示元件无法获得由DC-DC电路提供的用于点亮面板的EL电压，即EL高电平ELVDD和EL低电平ELVSS。
因此，为了避免由于EL高电平ELVDD异常变高导致的开机闪屏现象以及由于DC-DC失效而无法点亮显示元件的现象，关键在于当EL高电平ELVDD异常变高时使大电流无法通过DTFT，从而不影响EL低电平ELVSS的电压，即不影响显示元件的驱动电压和SSD电路的检测电压。
驱动管DTFT的导通与截止取决于DTFT的栅极-源极电压VGS。在源极电压(即EL高电平EVLDD)无法控制的情况下，可以通过改变DTFT的栅极电压来控制VGS。由图1所示的像素补偿电路可知，驱动管DTFT的栅极电压可通过参考电压输入Vref，复位电压输入Vinit，以及数据信号输入Vdata中的一个或多个来控制。因此，可以在EL高电平ELVDD启动之前，先跳变Vref、Vinit和Vdata中的一个或多个来抬高驱动管DTFT的栅极电压使得即使ELVDD出现异常升高时也能够提供足够关断DTFT的栅极-源极电压VGS，再在EL低电平开始输出之后将所跳变的Vref、Vinit和Vdata中的一个或多个再次跳变以恢复显示元件的正常显示。
针对上述分析，图3示出对现有像素补偿电路的DC-DC驱动时序改进后的DC-DC驱动时序。其中，参考电压输入Vref在EL高电平ELVDD开始输出之前从零电压升高到高于额定参考电压Vref2的参考电压Vref1，而参考电压输入Vref在EL低电平ELVSS开始输出之后从Vref1降低到额定参考电压Vref2。同时，复位电压输入Vinit在EL高电平ELVDD开始输出之前从零电压降低到高于额定复位电压Vinit2的复位电压Vinit1，复位电压输入Vinit在EL低电平ELVSS开始输出之后再从Vinit1降低到额定复位电压Vinit2。
参考电压Vref1和复位电压Vinit的选择使得在EL高电平ELVDD启动输出到EL低电平ELVSS启动输出这段时间，即SSD电路检测所在的时间期间内始终控制驱动管DTFT的栅极电压以关断DTFT。例如，当EL高电平ELVDD突然跳变时，参考电压Vref1和复位电压Vinit1值使驱动管DTFT的栅极-源极电压 VGS大于其阈值电压Vth，即满足Vinit1+Vref1-ELVDD1>Vth，从而确保驱动管DTFT关断。参考电压输入Vref和复位电压输入Vinit的跳变在该期间持续，充分保证显示元件在上电过程中正常显示，不会有大电流导致显示面板闪屏现象，以及SSD电路的面板短路检测也不会受到影响。
因此，采用改进的DC-DC驱动时序的像素补偿电路驱动显示元件在工作阶段的状态变为：
在复位阶段，将Rest信号置于低电平，第一和第二开关元件T1、T2导通。然后将EL高电平ELVDD施加到节点1，复位电压Vinit1施加到节点2；
在数据写入阶段，将驱动管DTFT的栅极Gate信号置于低电平，第三和第四开关元件T3、T4导通。然后数据信号输入Vdata施加到节点1，由于电容器C两端的电压不能瞬变，因此节点2的节点电压为Vdata+Vinit1-ELVDD。当ELVDD为零时，节点2的电压为Vdata+Vinit1；
在发光阶段，将EM信号置于低电平，第五和第六开关元件T5、T6导通。然后将参考电压Vref1施加到节点1，由于电容器C两端电压不能瞬变，因此节点2的电压为Vdata+Vinit1+Vref1-Vdata，消除Vdata项后节点2的电压为Vint1+Vref1。
在显示面板正常点亮后，VGS＝Vinit1+Vref1-ELVDD1>Vth，则驱动管DTFT关断，运行正常。
根据上述改进的DC-DC驱动时序的像素补偿电路在工作阶段中节点1和节点2在显示第一帧图像的节点电压如表2所示。
表2改进驱动时序下的节点1和2的节点电压
周期 节点1 节点2
Rest开启 ELVDD Vinit1
Gate开启 Vdata Vdata+Vinit1
Em开启 Vref1 Vinit1+Vref1
上述改进的DC-DC驱动时序中对参考电压输入Vref、复位电压输入Vinit的电压跳变可通过电压跳变单元实现。
电压跳变单元可通过如图4所示的降压单元和如图5所示的升压单元来实现。将参考电压输入Vref、复位电压输入Vinit和数据信号输入Vdata分别作为降压单元或升压单元的输入电压Vin，降压单元或升压单元通过脉冲(PLUSE)控制输出的输出电压Vout作为跳变后的参考电压输入Vref、复位电压输入Vinit和数据信号输入Vdata。其中，开关元件采用MOS管，也可以采用双极性晶体管或其它具有选通信号输入的开关器件。
如图4所示的降压单元包括MOS管M1、电感器L1、二极管D1、电容器C1，以及输入电压Vin、输出电压Vout。MOS管M1采用PWM(脉冲宽度调制)信号驱动，其中信号周期为TS，导通时间为TON，则占空比D＝TON/TS<1。
当MOS管M1导通时，二极管D1关断，电流方向如虚线1所示，电感器两端电压为VL,ON＝Vin-Vout＝L(dIL,ON/dt)(假定VM＝0)；
当MOS管M1关断时，电感器L1续流，二极管D1导通，如虚线2所示，电感器两端电压为VL,OFF＝-Vout＝L(dIL,OFF/dt)(假定VD＝0)。
当降压单元处于稳态时，MOS管的一个开关周期内的总电流变化量为零，即MOS管导通时通过电感器的电流增加量和MOS管关断时电感器的电流减少量相等，因此电感器在一个开关周期内的电压为：
VL(t)＝VL,ON(t)+VL,OFF(t)＝(Vin-Vout)*DTS+(-Vout)*(1-D)TS＝0
因此，Vout＝D*VIN
其中，VL为电感器电压，VM为MOS管M1的源极-漏极电压，VD为二极管电压。
如图5所示的升压单元包括MOS管M2、电感器L2、二极管D2、电容器C2，以及输入电压Vin、输出电压Vout。MOS管2采用PWM(脉冲宽度调制)信号驱动，其中信号周期为TS，导通时间为TON，占空比D＝TON/TS<1。
当MOS管M2导通时，二极管D2关断，如虚线1所示，电感器两端电压为VL,ON＝Vin(假定VM＝0)；
当MOS管M2关断时，电感器L2续流，二极管导通，如虚线2所示，电感器两端电压为VL,OFF＝Vin-Vout(假定VD＝0)。
与图4中的降压单元的推导类似，电感器在一个开关周期内的电压为：
VL(t)＝VL,ON(t)+VL,OFF(t)＝Vin*DTS+(Vin-Vout)*(1-D)TS＝0
因此，Vout＝(1-D)-1*Vin
上述降压和升压单元也可以集成到具有寄存器的IC集成电路中作为电压跳变单元。通过修改寄存器设置来输出改进的驱动时序，可以使用IC完成显示面板的DC-DC驱动。IC例如但不限于采用TPS 65633或DW 8722。
上文描述了采用参考电压输入Vref和复位电压输入Vinit同时跳变的改进DC-DC驱动方法、控制电路和显示装置。另外，还可以通过单独跳变参考电压输入Vref、复位电压输入Vinit和数据信号输入Vdata中的一个或者将三者中的多个结合以在EL高电平ELVDD启动输出之前到EL低电平ELVSS启动输出之后期间保持驱动管DTFT关断。
例如，图6所示驱动时序描述了单独跳变复位电压输入Vinit的本公开的实施例。在不修改参考电压输入Vref和数据信号输入Vdata的情况下，复位电压输入Vref在EL低电平ELVSS开始输出之前保持零电压，而在EL低电平ELVSS开始输出之后从零电压降低到额定复位电压。
进一步，还可以改进电压跳变的方式。图7示出具有多次跳变的参考电压输入Vref的DC-DC驱动时序。在不修改复位电压输入Vinit的情况下，参考电压输入Vref在EL高电平ELVDD开始输出之前先升高到额定参考电压，再以例如阶梯方式升高到高于额定参考电压的参考电压，随后EL高电平ELVDD开始输出。在ELVSS开始输出后，参考电压输入Vref降低到额定参考电压。
上述进一步改进也适用于参考电压输入Vref、复位电压输入Vinit和数据信号输入Vdata中的其它输入。
本领域技术人员将理解，还可以采用示例实施例中未示出但可以容易想到的其它电压跳变方式解决克服开机闪屏和DC-DC失效的问题。
通过本公开所提供的采用电压跳变来在EL高电平开始输出之前关断驱动管DTFT并且在EL低电平开始输出之后再次电压跳变来开启驱动管DTFT的有机发光二极管的驱动方法、驱动电路和显示装置，能够改善OLED或AMOLED显示装置的显示效果，提高SSD电路的检测效率，避免开机闪屏和DC-DC失效而无法点亮显示元件的现象，从而有效减少显示装置和驱动电路的功率和寿命损耗。
出于示例和说明目的给出了对本公开的描述，但所述描述并非旨在是穷举的或是将本公开限于所公开的形式。对于所属技术领域的普通技术人员来说许多修改和变化都将是显而易见的。任何采用信号/电压跳变来在开机过程中关断DTFT以克服开机闪屏和DC-DC驱动失效的技术方案，均落入本公开的范围内。实施例的选择和描述是为了最佳地解释本公开的原理和实际应用，并且当适合于所构想的特定使用时，使得所属技术领域的其它普通技术人员能够理解本公开的具有各种修改的各种实施例。因此，公开的特定布置仅指说明性并且不限于公开概念的范围，该范围由所附权利要求的全部范围及其任何和全部等价来给出。

Claims (14)

  1. 一种有机发光二极管的驱动方法，用于像素补偿电路，所述像素补偿电路具有参考电压输入、复位电压输入、数据信号输入、以及用于驱动显示元件的驱动管(DTFT)，所述驱动管具有接收控制信号的控制极，接收输入信号的第一极和用于输出输出信号的第二极，所述参考电压输入、所述复位电压输入和所述数据信号输入分别耦接到所述驱动管的控制极，所述像素补偿电路的EL高电平(ELVDD)施加到所述驱动管的第一极，所述驱动管的第二极耦接显示元件的第一极，显示元件的第二极电压为所述像素补偿电路的EL低电平(ELVSS)，其中，通过在EL高电平开始输出之前跳变所述参考电压输入、所述复位电压输入、所述数据信号输入中的一个或多个来关断驱动管并且在EL低电平开始输出之后将所跳变的所述参考电压输入、所述复位电压输入、所述数据信号输入中的一个或多个再次跳变来开启驱动管。
  2. 根据权利要求1所述的有机发光二极管的驱动方法，其中，所述参考电压输入在EL高电平开始输出之前从零电压跳变到第一参考电压，所述参考电压输入在EL低电平开始输出之后从第一参考电压跳变到第二参考电压，所述第一参考电压高于所述第二参考电压，所述第二参考电压等于参考电压输入的额定电压。
  3. 根据权利要求2所述的有机发光二极管的驱动方法，其中，所述参考电压输入在EL高电平开始输出之前先从零电压跳变到第二参考电压，再从第二参考电压跳变到第一参考电压。
  4. 根据权利要求1至3中任一项所述的有机发光二极管的驱动方法，其中，所述复位电压输入在EL高电平开始输出之前从零电压跳变到第一复位电压，所述复位电压输入在EL低电平开始输出之后从所述第一复位电压跳变到第二复位电压，所述第一复位电压高于所述第二复位电压，所述第二复位电压等于复位电压输入的额定电压。
  5. 根据权利要求1至3中任一项所述的有机发光二极管的驱动方法，其中，所述复位电压输入在EL低电平开始输出之前保持为零电压，在EL低电平开始输出之后从零电压跳变到第二复位电压，所述第二复位电压等于复位电压输入的额定电压。
  6. 根据权利要求1至5中任一项所述的有机发光二极管的驱动方法，所述数据信号输入在EL高电平开始输出之前跳变到第一数据信号，所述数据信号输入在EL低电平开始输出之后从第一数据信号跳变到第二数据信号。
  7. 一种有机发光二极管的驱动电路，包括直流-直流控制电路和像素补偿电路，所述直流-直流控制电路与像素补偿电路相连接，所述像素补偿电路具有参考电压输入、复位电压输入、数据信号输入、以及用于驱动显示元件的驱动管(DTFT)，所述驱动管具有接收控制信号的控制极，接收输入信号的第一极和用于输出输出信号的第二极，所述参考电压输入、所述复位电压输入和所述数据信号输入分别耦接到驱动管的控制极，所述像素补偿电路的EL高电平(ELVDD)施加到驱动管的第一极，驱动管的第二极耦接显示元件的第一极，显示元件的第二极电压为所述像素补偿电路的EL低电平(ELVSS)，其中，所述直流-直流控制电路包括电压跳变单元，所述电压跳变单元 被配置为通过在EL高电平开始输出之前跳变所述参考电压输入、所述复位电压输入、所述数据信号输入中的一个或多个来关断驱动管并且在EL低电平开始输出之后将所跳变的所述参考电压输入、所述复位电压输入、所述数据信号输入中的一个或多个再次跳变来开启驱动管。
  8. 根据权利要求7所述的有机发光二极管的驱动电路，其中，所述电压跳变单元包括第一升压单元和第一降压单元，所述第一升压单元被配置为使得所述参考电压输入在EL高电平开始输出之前从零电压跳变到第一参考电压，所述第一降压单元被配置为使得所述参考电压输入在EL低电平开始输出之后从第一参考电压跳变到第二参考电压，所述第一参考电压高于所述第二参考电压，所述第二参考电压等于参考电压输入的额定电压。
  9. 根据权利要求8所述的有机发光二极管的驱动电路，其中，所述第一升压单元被配置为使得所述参考电压输入在EL高电平开始输出之前先从零电压跳变到所述第二参考电压，再从所述第二参考电压跳变到第一参考电压。
  10. 根据权利要求7至9中任一项所述的有机发光二极管的驱动电路，其中，所述电压跳变单元包括第二升压单元和第二降压单元，所述第二升压单元被配置为使得所述复位电压输入在EL高电平开始输出之前从零电压跳变到第一复位电压，所述第二降压单元被配置为使得所述复位电压输入在EL低电平开始输出之后从所述第一复位电压跳变到第二复位电压，所述第一复位电压高于所述第二复位电压，所述第二复位电压等于复位电压输入的额定电压。
  11. 根据权利要求7至9中任一项所述的有机发光二极管的驱动电路，其中，所述电压跳变单元包括第二降压单元，所述复位电压输入在EL低电平开始输出之前保持为零电压，所述第二降压单元被配置为使得所述复位电压输入在EL低电平开始输出之后从零电压跳变到第二复位电压，所述第二复位电压等于复位电压输入的额定电压。
  12. 根据权利要求7至11中任一项所述的有机发光二极管的驱动电路，其中，所述电压跳变单元包括第三升压单元和第三降压单元，所述第三升压单元被配置为使得所述数据信号输入在EL高电平开始输出之前从零电压跳变到第一数据信号，所述第三降压单元被配置为使得所述数据信号输入在EL低电平开始输出之后从第一数据信号跳变到第二数据信号。
  13. 根据权利要求7至12中任一项所述的有机发光二极管的驱动电路，其中，所述电压跳变单元集成到IC中。
  14. 一种OLED显示装置，包括如权利要求7至13中任一项所述的有机发光二极管的驱动电路。
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