WO2020019398A1 - Oled驱动电路及amoled显示面板 - Google Patents

Oled驱动电路及amoled显示面板 Download PDF

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Publication number
WO2020019398A1
WO2020019398A1 PCT/CN2018/102958 CN2018102958W WO2020019398A1 WO 2020019398 A1 WO2020019398 A1 WO 2020019398A1 CN 2018102958 W CN2018102958 W CN 2018102958W WO 2020019398 A1 WO2020019398 A1 WO 2020019398A1
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Prior art keywords
thin film
film transistor
driving
terminal
oled
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PCT/CN2018/102958
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English (en)
French (fr)
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李雪
侯学顺
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武汉华星光电半导体显示技术有限公司
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Priority to US16/095,868 priority Critical patent/US10522083B1/en
Publication of WO2020019398A1 publication Critical patent/WO2020019398A1/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]
    • G09G3/3275—Details of drivers for data electrodes
    • G09G3/3291—Details of drivers for data electrodes in which the data driver supplies a variable data voltage 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
    • 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

Definitions

  • the invention relates to the technical field of display driving, in particular to an OLED driving circuit and an AMOLED display panel.
  • Organic Light-Emitting Diode (OLED) display panels are favored by people because they are thin, energy-saving, wide viewing angle, wide color gamut, and high contrast.
  • Organic light-emitting diode display panels are divided into passive organic light-emitting diode display panels. (PMOLED) and active organic light emitting diode display panel (AMOLED).
  • the OLED driving circuit commonly used in AMOLED is shown in Figure 1.
  • the OLED driving circuit is used to drive OLED.
  • the OLED driving circuit includes a switch thin film transistor (Switch TFT) T2, a driver thin film transistor (Driver TFT) T1, and a
  • the storage capacitor Cst is also called a 2T1C structure.
  • a gate of the switching thin film transistor T2 receives an n-th scan signal Scan (n), a drain of the switching thin film transistor T2 receives a data voltage Vdata, and a source of the switching thin film transistor T2 is electrically connected to the driving thin film.
  • the source of the switching thin film transistor T2 and the drain of the switching thin film transistor T2 are turned on or off under the control of the n-th scan signal Scan (n).
  • the data voltage Vdata is transmitted to the driving thin film
  • the source of the driving thin film transistor T1 is electrically connected to a power supply voltage VDD
  • the power supply voltage VDD is a high potential voltage
  • the drain of the driving thin film transistor T1 is electrically connected to a positive electrode of the OLED.
  • the negative electrode of the OLED is electrically connected to a low potential voltage VSS.
  • Both ends of the storage capacitor Cst are electrically connected to a gate of the driving thin film transistor T1 and a drain of the driving thin film transistor T1, respectively.
  • the current I OLED flowing through the OLED is:
  • I OLED k (Vgs-Vth) 2 .
  • I OLED is a current flowing through the OLED, also referred to as a driving current of the OLED;
  • k is a current amplification factor of the driving thin film transistor T1, which is determined by the characteristics of the driving thin film transistor T1 itself;
  • Vgs is The voltage between the gate and the source of the driving thin film transistor T1;
  • Vth is a threshold voltage of the driving thin film transistor T1. It can be seen that the driving current of the OLED is related to the threshold voltage Vth of the driving thin film transistor T1.
  • the threshold voltage Vth of the driving thin film transistor T1 is easy to drift, which causes the driving current I OLED of the OLED to change, the driving current I OLED of the OLED changes will cause the light emitting brightness of the OLED to change, and then affect the OLED. Picture quality of AMOLED display panel.
  • the technical problem to be solved by the embodiments of the present invention is to provide an OLED driving circuit and an AMOLED display panel.
  • the problem that the driving current of the OLED changes due to the threshold voltage drift of the driving thin film transistor can be improved.
  • an embodiment of the first aspect of the present invention provides an OLED driving circuit, including:
  • a switching thin film transistor receives a scanning signal, a first end of the switching thin film transistor is electrically connected to a first node, and a second end of the switching thin film transistor is electrically connected to a second node;
  • Driving a thin film transistor a first terminal of the driving thin film transistor receiving a power supply voltage, a gate of the driving thin film transistor being electrically connected to the first node, and a second terminal of the driving thin film transistor being electrically connected to the second node;
  • a storage capacitor a first electrode of the storage capacitor receives a data voltage, and a second electrode of the storage capacitor is connected to a first node;
  • a third thin film transistor whose gate receives a reset signal, its first terminal receives a reset voltage, and its second terminal is electrically connected to the first node;
  • a sixth thin film transistor a gate of which receives an enable signal, and a first end of which is electrically connected to a second node;
  • the anode of the OLED is electrically connected to the second terminal of the sixth thin film transistor, and the anode of the OLED is loaded with a low-level voltage
  • the erasing module is electrically connected to the first electrode of the storage capacitor and the first terminal of the driving thin film transistor, respectively.
  • the erasing module receives a data voltage and a power supply voltage, respectively.
  • the erasing module, the third thin film transistor, and the sixth thin film transistor are commonly used.
  • the method is used to eliminate a change in a driving current of the OLED due to a drift of a threshold voltage of the driving thin film transistor.
  • the scan signal is an n-th scan signal, where n is an integer greater than or equal to two.
  • the elimination module includes a fourth thin film transistor and a fifth thin film transistor, wherein a gate of the fourth thin film transistor receives a reset signal, a first end of the fourth thin film transistor is electrically connected to a first electrode of a storage capacitor, and a second The terminal is electrically connected to the first terminal of the driving thin film transistor, the gate of the fifth thin film transistor receives the n-1th scanning signal, the first terminal receives the data voltage, and the second terminal is electrically connected to the first electrode of the storage capacitor.
  • the reset signal is the same as the n-1th scan signal, and
  • the third thin film transistor and the fourth thin film transistor are turned on, a first electrode of the storage capacitor stores a power supply voltage, a second electrode stores a reset voltage, and the driving thin film transistor is turned on;
  • the fourth thin film transistor continues to be turned on, and the switching thin film transistor is turned on, when the voltage between the gate of the driving thin film transistor and its first terminal is equal to its threshold voltage, Driving the thin film transistor off;
  • the fifth thin film transistor is turned on, and the data voltage is transmitted to the first electrode of the storage capacitor;
  • the sixth thin film transistor is turned on, and the OLED emits light.
  • the switching thin film transistor, the driving thin film transistor, the third thin film transistor, the fifth thin film transistor, and the sixth thin film transistor are P-type thin film transistors, and the fourth thin film transistor is an N-type thin film transistor.
  • the erasing module further includes a seventh thin film transistor and an eighth thin film transistor.
  • the first terminal of the driving thin film transistor receives a power supply voltage via the seventh thin film transistor.
  • the gate of the seventh thin film transistor receives The first terminal of the enable signal receives the power supply voltage, the second terminal is electrically connected to the first terminal of the driving thin film transistor, the gate of the eighth thin film transistor receives the n-th scanning signal, and the first terminal receives the reference voltage. Its second terminal is electrically connected to the first terminal of the driving thin film transistor.
  • the reset signal is the same as the enable signal, and
  • the third thin film transistor and the fifth thin film transistor are turned on, a first electrode of the storage capacitor stores a data voltage, and a second electrode stores a reset voltage;
  • the fifth thin film transistor continues to be turned on, the switching thin film transistor and the eighth thin film transistor are turned on, the driving thin film transistor is turned on at the beginning, and when the gate of the driving thin film transistor is turned on When the voltage between the electrode and its first terminal is equal to its threshold voltage, the driving thin film transistor is turned off;
  • the seventh thin film transistor, the fourth thin film transistor, and the sixth thin film transistor are turned on, and the OLED emits light.
  • the switching thin film transistor, the driving thin film transistor, the third thin film transistor, the fourth thin film transistor, the fifth thin film transistor, the sixth thin film transistor, the seventh thin film transistor, and the eighth thin film transistor are all P-type thin film transistors or N-type thin film transistors. Thin film transistor.
  • the reset time period, the compensation threshold voltage time period, the writing time period, and the light emission time period are included in one cycle of the OLED driving circuit.
  • the first terminal is a source and the second terminal is a drain; or the first terminal is a drain and the second terminal is a source.
  • An embodiment of the second aspect of the present invention provides an AMOLED display panel.
  • the AMOLED display panel includes the OLED driving circuit described above.
  • the OLED driving circuit further includes a third thin film transistor, a sixth thin film transistor, and an erasing module, the three are used to eliminate the driving current flowing through the OLED due to the threshold voltage drift of the driving thin film transistor.
  • the change Due to the settings of the third thin film transistor, the sixth thin film transistor, and the elimination module, the threshold voltage of the driving thin film transistor is not included in the calculation formula of the driving current, so that the influence of the drift of the threshold voltage of the driving thin film transistor on the driving current can be eliminated.
  • the driving current is relatively stable, the luminous brightness of the OLED is relatively uniform, and the picture quality of the AMOLED display panel is better.
  • FIG. 1 is a schematic diagram of a prior art OLED driving circuit
  • FIG. 2 is a schematic diagram of an OLED driving circuit according to a first embodiment of the present invention
  • FIG. 3 is a timing diagram of an OLED driving circuit according to the first embodiment of the present invention.
  • FIG. 4 is a schematic diagram of an OLED driving circuit according to a second embodiment of the present invention.
  • FIG. 5 is a timing diagram of an OLED driving circuit according to a second embodiment of the present invention.
  • the first embodiment of the present invention provides an OLED driving circuit, as shown in FIG. 2, which includes an OLED, a storage capacitor Cst, a driving thin film transistor T1 and a switching thin film transistor T2.
  • the OLED is used to emit light; the first electrode of the storage capacitor Cst receives the data voltage Vdata, and the second electrode of the storage capacitor Cst is electrically connected to the first node B; the first terminal of the switching thin film transistor T2 is electrically connected To the first node B, the second terminal of the switching thin film transistor T2 is electrically connected to the second node C.
  • the gate of the switching thin film transistor T2 receives a scanning signal, where the scanning signal is an n-th scanning signal Scan (n), where n Is an integer greater than or equal to 2, such as 2, 3, 4, 5, 6, 7, 8, 9, 10, etc .; the first end of the driving thin film transistor T1 receives the power supply voltage VDD.
  • the power supply voltage VDD is a high-level voltage
  • the second terminal of the driving thin film transistor T1 is electrically connected to the second node C
  • the gate of the driving thin film transistor T1 is electrically connected to the first node B
  • the positive electrode of the OLED is indirectly electrically connected to the second node C.
  • the negative pole is loaded with a low voltage VSS.
  • the first terminal of the switching thin film transistor T2 and the driving thin film transistor T1 is a source, and the second terminal is a drain.
  • the first terminal of the switching thin film transistor and the driving thin film transistor is a drain, and the second terminal is a source.
  • the OLED driving circuit further includes a third thin film transistor T3 and a sixth thin film.
  • Transistor T6 and the elimination module (the part marked by the dashed box in the figure), wherein the gate of the third thin film transistor T3 receives a reset signal Reset, the first terminal of the third thin film transistor T3 receives a reset voltage VI, and the reset voltage VI is low.
  • the second terminal of the third thin film transistor T3 is electrically connected to the first node B, so that the second terminal of the third thin film transistor T3 is electrically connected to the second electrode of the storage capacitor Cst, the first terminal of the switching thin film transistor T2, and the driver.
  • the gate of the sixth thin film transistor T6 receives the enable signal EM.
  • the first terminal of the sixth thin film transistor T6 is electrically connected to the second node C.
  • the second terminal of the sixth thin film transistor T6 is electrically connected to the anode of the OLED, that is, the driving thin film.
  • the transistor T1 is indirectly electrically connected to the anode of the OLED, and specifically is electrically connected to the anode of the OLED via the sixth thin film transistor T6.
  • the erasing module is electrically connected to the first electrode of the storage capacitor Cst and the first terminal of the driving thin film transistor T2 respectively.
  • the erasing module receives the data voltage Vdata and the power voltage VDD, respectively.
  • the erasing module, the third thin film transistor, the first The six thin film transistors are commonly used to eliminate the change in the driving current of the OLED caused by the threshold voltage of the driving thin film transistor T1.
  • the elimination module includes a fourth thin film transistor T4 and a fifth thin film transistor T5.
  • the gate of the fourth thin film transistor T4 receives the reset signal Pro.
  • the reset signal Pro is the n-1th scan signal Scan (n-1).
  • the fourth thin film transistor The first terminal of T4 is electrically connected to the first electrode of the storage capacitor Cst, and the second terminal of the fourth thin film transistor T4 is electrically connected to the first terminal of the driving thin film transistor T1.
  • the gate of the fifth thin film transistor T5 receives the n-1th stage scanning signal Scan (n-1), the first terminal of the fifth thin film transistor T5 receives the data voltage Vdata, and the second terminal of the fifth thin film transistor T5 is electrically connected to the memory.
  • the first electrode of the capacitor Cst receives the data voltage via the fifth thin film transistor T5, and receives the power supply voltage VDD via the fourth thin film transistor T4.
  • the first terminal of the third thin film transistor T3, the fourth thin film transistor T4, the fifth thin film transistor T5, and the sixth thin film transistor T6 is a source, and the second terminal is a drain.
  • the first terminal of the third thin film transistor, the fourth thin film transistor, the fifth thin film transistor, and the sixth thin film transistor is a drain, and the second terminal is a source.
  • the switching thin film transistor T2, the driving thin film transistor T1, the third thin film transistor T3, the fifth thin film transistor T5, and the sixth thin film transistor T6 are P-type thin film transistors, and the fourth thin film transistor T4 is an N-type thin film Transistor.
  • the OLED light emission of the OLED driving circuit is periodic.
  • One cycle of the OLED driving circuit includes a reset time period, a compensation threshold voltage time period, a writing time period, and a light emission time. See FIG. 3, and the following is combined with FIG. 2 The driving of the OLED driving circuit is described with FIG. 3.
  • the reset signal Reset is at a low level.
  • the third thin film transistor T3 is turned on, and the reset voltage VI is transmitted to the first node B, that is, is transmitted to the driving thin film transistor.
  • the driving thin film transistor T1 is turned on and the reset voltage VI is stored in At the second electrode of the storage capacitor Cst; at the same time, during the reset period, the n-1 scanning signal Scan (n-1) is high, so that the fourth thin film transistor T4 is turned on, and the power supply voltage VDD is supplied to The first electrode of the storage capacitor Cst.
  • the n-th stage scanning signal Scan (n) is at a low level, so that the switching thin film transistor T2 is turned on.
  • the driving thin film transistor T1 is turned on until the voltage between the gate and the first terminal of the driving thin film transistor is the same as the threshold voltage of the driving thin film transistor T1.
  • the driving thin film transistor T1 is turned off, that is, when the gate of the driving thin film transistor T1 and its first When the voltage between one end is equal to its threshold voltage, the driving thin film transistor T1 is turned off, thereby:
  • Vs-Vg ⁇ Vth ⁇
  • Vg Vs- ⁇ Vth ⁇
  • Vg VDD- ⁇ Vth ⁇ .
  • the scan signal Scan (n-1) of the n-1 level is low, the fourth thin film transistor T4 is turned off, and the fifth thin film transistor T5 is turned on.
  • the enable signal EM is turned to a low level, so that the sixth thin film transistor T6 is turned on, and the driving current I OLED can emit light through the OLED.
  • the driving current calculation formula is as follows:
  • I OLED k (Vgs- ⁇ Vth ⁇ ) 2
  • K is a current amplification factor for driving the thin film transistor T1
  • VDD is a power supply voltage
  • Vdata is a data voltage
  • the threshold voltage Vth of the driving thin film transistor is not included in the formula, the influence of the drift of the threshold voltage Vth of the driving thin film transistor T1 on the driving current I OLED can be eliminated, thereby driving the driving current I OLED. It is relatively stable, so that the OLED's luminous brightness is relatively uniform, and the picture quality of the AMOLED display panel is better. Moreover, the problem of "brightness" of the OLED during the reset period can be improved.
  • the switching thin film transistor T2, the driving thin film transistor T1, the third thin film transistor T3, the fifth thin film transistor T5, and the sixth thin film transistor T6 are N-type thin film transistors
  • the fourth thin film transistor T4 is a P-type thin film transistor.
  • This embodiment also provides an AMOLED display panel including the OLED driving circuit described above.
  • the driving current I OLED is related to the power supply voltage VDD, and when the OLED far from the power supply voltage VDD receives the power supply voltage VDD, the power supply voltage VDD needs to be transmitted over a long distance, which causes the power supply voltage VDD to decrease.
  • the driving current I OLED will deviate, that is, an IR drop problem that is familiar to those skilled in the art.
  • the present invention describes a second embodiment.
  • FIG. 4 is a schematic diagram of an OLED driving circuit according to a second embodiment of the present invention.
  • the circuit in FIG. 4 is similar to the circuit in FIG. 2, so the same original symbols represent the same components.
  • the main difference between this embodiment and the first embodiment is the elimination module.
  • the elimination module further includes a seventh thin film transistor T7 and an eighth thin film transistor T8.
  • the first terminal of the driving thin film transistor T1 receives the power supply voltage VDD via the seventh thin film transistor T7.
  • the gate of the seventh thin film transistor T7 receives the enable signal EM
  • the first terminal of the seventh thin film transistor T7 receives the power supply voltage VDD
  • the second terminal of the seventh thin film transistor T7 is electrically connected to the first driving thin film transistor T1.
  • the gate of the eighth thin film transistor T8 receives the n-th scan signal Scan (n), the first terminal of the eighth thin film transistor T8 receives the reference voltage Vref, and the second terminal of the eighth thin film transistor T8 is electrically connected to the driving thin film transistor T1.
  • the reset signal Pro is the enable signal EM, and the two signals are completely the same.
  • the first terminal of the seventh thin film transistor T7 and the eighth thin film transistor T8 is a source, and the second terminal is a drain. In other embodiments of the present invention, the first terminal of the seventh thin film transistor and the eighth thin film transistor is a drain, and the second terminal is a source.
  • the switching thin film transistor T2, the driving thin film transistor T1, the third thin film transistor T3, the fourth thin film transistor T4, the fifth thin film transistor T5, the sixth thin film transistor T6, the seventh thin film transistor T7, and the eighth thin film transistor T8 is a P-type thin film transistor.
  • the OLED light emission of the OLED driving circuit is periodic.
  • One cycle of the OLED driving circuit includes a reset time period R, a compensation threshold voltage time period T, a writing time period W, and a light emission time E. See FIG. 5.
  • the driving of the OLED driving circuit is described below with reference to FIGS. 4 and 5.
  • the reset signal Reset is at a low level.
  • the driving thin film transistor T1 is turned off, thereby:
  • Vs-Vg ⁇ Vth ⁇
  • Vg Vs- ⁇ Vth ⁇
  • Vg Vref- ⁇ Vth ⁇ .
  • the signals received by the OLED driving circuit are the same, the enable signal EM is at a low level, and the fourth thin film transistor T4, the sixth thin film transistor T6, and the seventh thin film
  • the transistor T7 is turned on, the n-1th stage scanning signal Scan (n-1) is at a high level, and the fifth thin film transistor T5 is turned off.
  • the sixth thin film transistor T6, the seventh thin film transistor T7, and the driving thin film transistor T1 are turned on.
  • the calculation formula for the driving current I OLED is as follows:
  • I OLED k (Vgs- ⁇ Vth ⁇ ) 2
  • k is a current amplification factor for driving the thin film transistor T1
  • Vdata is a data voltage
  • Vref is a reference voltage
  • the driving current I OLED since there is no threshold voltage Vth of the driving thin film transistor in the formula, the influence of the threshold voltage drift of the driving thin film transistor T1 on the driving current I OLED can be eliminated, and the driving current is relatively stable. As a result, the OLED's luminous brightness is relatively uniform, and the picture quality of the AMOLED display panel is better. Moreover, the problem of "brightness" of the OLED during the reset process can be improved. In addition, there is no power supply voltage VDD in the formula of the driving current I OLED . Therefore, even if the power supply voltage VDD decreases over a long distance and the power supply voltage VDD decreases, the problem of IR drop does not occur, so that the driving current is more stable, and OLED light emission is more stable.
  • the switching thin film transistor, the driving thin film transistor, the third thin film transistor, the fourth thin film transistor, the fifth thin film transistor, the sixth thin film transistor, the seventh thin film transistor, and the eighth thin film transistor are all N-type Thin film transistor.
  • the present invention has the following advantages:
  • the OLED driving circuit further includes a third thin film transistor, a sixth thin film transistor, and an erasing module, the three are used to eliminate the driving current flowing through the OLED due to the threshold voltage drift of the driving thin film transistor.
  • the change Due to the settings of the third thin film transistor, the sixth thin film transistor, and the elimination module, the threshold voltage of the driving thin film transistor is not included in the calculation formula of the driving current, so that the influence of the drift of the threshold voltage of the driving thin film transistor on the driving current can be eliminated.
  • the driving current is relatively stable, the luminous brightness of the OLED is relatively uniform, and the picture quality of the AMOLED display panel is better.

Abstract

本发明实施例公开了一种OLED驱动电路，包括：开关薄膜晶体管；驱动薄膜晶体管；存储电容；第三薄膜晶体管，其栅极接收复位信号，其第一端接收复位电压，其第二端电连接第一节点；第六薄膜晶体管，其栅极接收使能信号，其第一端电连接第二节点；OLED；消除模块，其分别与存储电容的第一电极、驱动薄膜晶体管的第一端电连接，所述消除模块分别接收数据电压和电源电压，所述消除模块、第三薄膜晶体管、第六薄膜晶体管共同用于消除由于所述驱动薄膜晶体管的阈值电压的漂移而导致的所述OLED的驱动电流的变化。本发明实施例还公开了一种AMOLED显示面板。采用本发明，具有改善由于驱动薄膜晶体管的阈值电压漂移而引起OLED的驱动电流变动的优点。

Description

OLED驱动电路及AMOLED显示面板
本发明要求2018年7月27日递交的发明名称为“OLED驱动电路及AMOLED显示面板”的申请号201810841303.4的在先申请优先权，上述在先申请的内容以引入的方式并入本文本中。
技术领域
本发明涉及显示驱动技术领域，特别是涉及一种OLED驱动电路及AMOLED显示面板。
背景技术
有机发光二极管(Organic Light-Emitting Diode，OLED)显示面板因为具备轻薄、节能、宽视角、色域广、对比度高等特性而备受人们的青睐，有机发光二极管显示面板分为被动式有机发光二极管显示面板(PMOLED)和主动式有机发光二极管显示面板(AMOLED)。其中AMOLED常用的OLED驱动电路如图1所示，所述OLED驱动电路用于驱动OLED，所述OLED驱动电路包括一个开关薄膜晶体管(Switch TFT)T2、一个驱动薄膜晶体管(Driver TFT)T1以及一个存储电容Cst，这种结构也被称为2T1C结构。所述开关薄膜晶体管T2的栅极接收第n级扫描信号Scan(n)，所述开关薄膜晶体管T2的漏极接收数据电压Vdata，所述开关薄膜晶体管T2的源极电连接至所述驱动薄膜晶体管T1的栅极。所述开关薄膜晶体管T2的源极和所述开关薄膜晶体管T2漏极在所述第n级扫描信号Scan(n)的控制下导通或者截止。当所述开关薄膜晶体管T2的源极和所述开关薄膜晶体管T2漏极在所述第n级扫描信号Scan(n)的控制下导通时，所述数据电压Vdata被传输至所述驱动薄膜晶体管T1的栅极。所述驱动薄膜晶体管T1的源极电连接至一电源电压VDD，所述电源电压VDD为高电位电压，所述驱动薄膜晶体管T1的漏极电连接至OLED的正极。所述OLED的负极电连接至一低电位电压VSS。所述存储电容Cst的两端分别电连接至所 述驱动薄膜晶体管T1的栅极及所述驱动薄膜晶体管T1的漏极。流经所述OLED的电流I OLED为：
I OLED＝k(Vgs-Vth) 2。
其中，I OLED为流经所述OLED的电流，也称为所述OLED的驱动电流；k为所述驱动薄膜晶体管T1的电流放大系数，由所述驱动薄膜晶体管T1自身的特性决定；Vgs为所述驱动薄膜晶体管T1的栅极与源极之间的电压；Vth为所述驱动薄膜晶体管T1的阈值电压。由此可见，所述OLED的驱动电流与所述驱动薄膜晶体管T1的阈值电压Vth有关。由于所述驱动薄膜晶体管T1的阈值电压Vth容易漂移，从而导致所述OLED的驱动电流I OLED变动，所述OLED的驱动电流I OLED变动会导致所述OLED的发光亮度发生变化，进而影响所述AMOLED显示面板的画质。
发明内容
本发明实施例所要解决的技术问题在于，提供一种OLED驱动电路及AMOLED显示面板。可改善由于驱动薄膜晶体管的阈值电压漂移而引起OLED的驱动电流变动的问题。
为了解决上述技术问题，本发明第一方面实施例提供了一种OLED驱动电路，包括：
开关薄膜晶体管，所述开关薄膜晶体管的栅极接收扫描信号，所述开关薄膜晶体管的第一端电连接到第一节点，所述开关薄膜晶体管的第二端电连接到第二节点；
驱动薄膜晶体管，所述驱动薄膜晶体管的第一端接收电源电压，所述驱动薄膜晶体管的栅极电连接所述第一节点，所述驱动薄膜晶体管的第二端电连接所述第二节点；
存储电容，所述存储电容的第一电极接收数据电压，所述存储电容的第二电极连接到第一节点；
第三薄膜晶体管，其栅极接收复位信号，其第一端接收复位电压，其第二端电连接第一节点；
第六薄膜晶体管，其栅极接收使能信号，其第一端电连接第二节点；
OLED，所述OLED的正极电连接所述第六薄膜晶体管的第二端，所述OLED的负极加载低电平电压；
消除模块，其分别与存储电容的第一电极、驱动薄膜晶体管的第一端电连接，所述消除模块分别接收数据电压和电源电压，所述消除模块、第三薄膜晶体管、第六薄膜晶体管共同用于消除由于所述驱动薄膜晶体管的阈值电压的漂移而导致的所述OLED的驱动电流的变化。
其中，所述扫描信号是第n级扫描信号，其中n为大于或等于2的整数。
其中，所述消除模块包括第四薄膜晶体管和第五薄膜晶体管，其中，所述第四薄膜晶体管的栅极接收重置信号，其第一端与存储电容的第一电极电连接，其第二端与驱动薄膜晶体管的第一端电连接，所述第五薄膜晶体管的栅极接收第n-1级扫描信号，第一端接收数据电压，第二端电连接至存储电容的第一电极。
其中，所述重置信号与所述第n-1级扫描信号相同，其中，
在复位时间段，所述第三薄膜晶体管和第四薄膜晶体管导通，所述存储电容的第一电极存储电源电压，第二电极存储复位电压，所述驱动薄膜晶体管导通；
在补偿阈值电压时间段，所述第四薄膜晶体管继续导通，所述开关薄膜晶体管导通，当所述驱动薄膜晶体管的栅极和其第一端之间的电压等于其阈值电压时所述驱动薄膜晶体管截止；
在写入时间段，所述第五薄膜晶体管导通，所述数据电压输送到存储电容的第一电极；
在发光时间段，所述第六薄膜晶体管导通，所述OLED发光。
其中，所述开关薄膜晶体管、驱动薄膜晶体管、第三薄膜晶体管、第五薄膜晶体管、第六薄膜晶体管为P型薄膜晶体管，所述第四薄膜晶体管为N型薄膜晶体管。
其中，所述消除模块还包括第七薄膜晶体管和第八薄膜晶体管，所述驱动薄膜晶体管的第一端经由所述第七薄膜晶体管接收电源电压，其中，所述第七薄膜晶体管的栅极接收使能信号，其第一端接收电源电压，其第二端电连接驱 动薄膜晶体管的第一端，所述第八薄膜晶体管的栅极接收第n级扫描信号，其第一端接收参考电压，其第二端电连接到驱动薄膜晶体管的第一端。
其中，所述重置信号与所述使能信号相同，其中，
在复位时间段，所述第三薄膜晶体管和第五薄膜晶体管导通，所述存储电容的第一电极存储数据电压，第二电极存储复位电压；
在补偿阈值电压时间段，所述第五薄膜晶体管继续导通，所述开关薄膜晶体管和所述第八薄膜晶体管导通，所述驱动薄膜晶体管开始时导通，当所述驱动薄膜晶体管的栅极和其第一端之间的电压等于其阈值电压时所述驱动薄膜晶体管截止；
在写入时间段和发光时间段，所述第七薄膜晶体管、第四薄膜晶体管、第六薄膜晶体管导通，所述OLED发光。
其中，所述开关薄膜晶体管、驱动薄膜晶体管、第三薄膜晶体管、第四薄膜晶体管、第五薄膜晶体管、第六薄膜晶体管、第七薄膜晶体管和第八薄膜晶体管均为P型薄膜晶体管或者N型薄膜晶体管。
其中，所述复位时间段、补偿阈值电压时间段、写入时间段和发光时间段包含在OLED驱动电路的一个周期内。
其中，所述第一端为源极，所述第二端为漏极；或者，所述第一端为漏极，所述第二端为源极。
本发明第二方面实施例提供了一种AMOLED显示面板，所述AMOLED显示面板包括上述的OLED驱动电路。
实施本发明实施例，具有如下有益效果：
由于所述OLED驱动电路还包括第三薄膜晶体管、第六薄膜晶体管、消除模块，三者共同用于消除由于所述驱动薄膜晶体管的阈值电压的漂移而带来的流经所述OLED的驱动电流的变化。由于第三薄膜晶体管、第六薄膜晶体管、消除模块的设置，所述驱动电流的计算公式中没有驱动薄膜晶体管的阈值电压，从而可以消除驱动薄膜晶体管的阈值电压的漂移对驱动电流的影响，从而驱动电流比较稳定，OLED的发光亮度比较均匀，AMOLED显示面板的画质较好。
附图说明
为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1是现有技术OLED驱动电路的示意图；
图2是本发明第一实施例OLED驱动电路的示意图；
图3是本发明第一实施例OLED驱动电路的时序图；
图4是本发明第二实施例OLED驱动电路的示意图；
图5是本发明第二实施例OLED驱动电路的时序图。
具体实施方式
下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
本申请说明书、权利要求书和附图中出现的术语“包括”和“具有”以及它们任何变形，意图在于覆盖不排他的包含。例如包含了一系列步骤或单元的过程、方法、系统、产品或设备没有限定于已列出的步骤或单元，而是可选地还包括没有列出的步骤或单元，或可选地还包括对于这些过程、方法、产品或设备固有的其它步骤或单元。此外，术语“第一”、“第二”和“第三”等是用于区别不同的对象，而并非用于描述特定的顺序。
第一实施例
本发明第一实施例提供一种OLED驱动电路，请参见图2，包括OLED、存储电容Cst、驱动薄膜晶体管T1和开关薄膜晶体管T2。在本实施例中，所述OLED用于发光；存储电容Cst的第一电极接收数据电压Vdata，存储电容Cst的第二电极电连接到第一节点B；开关薄膜晶体管T2的第一端电连接到第一节点B，开关薄膜晶体管T2的第二端电连接到第二节点C，开关薄膜晶体管 T2的栅极接收扫描信号，在这里扫描信号为第n级扫描信号Scan(n)，其中n为大于或等于2的整数，例如为2、3、4、5、6、7、8、9、10等；驱动薄膜晶体管T1的第一端接收电源电压VDD，在本实施例中，电源电压VDD为高电平电压，驱动薄膜晶体管T1的第二端电连接第二节点C，驱动薄膜晶体管T1的栅极电连接第一节点B；OLED的正极间接电连接到第二节点C，OLED的负极加载低电平电压VSS。在本实施例中，开关薄膜晶体管T2、驱动薄膜晶体管T1的第一端为源极，第二端为漏极。在本发明的其他实施例中，开关薄膜晶体管、驱动薄膜晶体管的第一端为漏极，第二端为源极。
为了消除驱动薄膜晶体管T1的阈值电压Vth的漂移对OLED的驱动电流的影响，造成OLED的发光亮度发生变化，在本实施例中，所述OLED驱动电路还包括第三薄膜晶体管T3、第六薄膜晶体管T6和消除模块(图中虚线框标识的部分)，其中，第三薄膜晶体管T3的栅极接收复位信号Reset，第三薄膜晶体管T3的第一端接收复位电压VI，复位电压VI为低电平，第三薄膜晶体管T3的第二端电连接到第一节点B，从而第三薄膜晶体管T3的第二端电连接到存储电容Cst的第二电极、开关薄膜晶体管T2的第一端、驱动薄膜晶体管T2的栅极。第六薄膜晶体管T6的栅极接收使能信号EM，第六薄膜晶体管T6的第一端电连接第二节点C，第六薄膜晶体管T6的第二端电连接至OLED的正极，也即驱动薄膜晶体管T1间接电连接到OLED的正极，具体为经由第六薄膜晶体管T6电连接到OLED的正极。所述消除模块分别与存储电容Cst的第一电极、驱动薄膜晶体管T2的第一端电连接，所述消除模块分别接收数据电压Vdata和电源电压VDD，所述消除模块、第三薄膜晶体管、第六薄膜晶体管共同用于消除由于驱动薄膜晶体管T1的阈值电压的漂移而带来的OLED的驱动电流的变化。
具体说来，在本实施例中，所述消除模块包括第四薄膜晶体管T4和第五薄膜晶体管T5。其中，第四薄膜晶体管T4的栅极接收重置信号Pro，在本实施例中，所述重置信号Pro即为第n-1级扫描信号Scan(n-1)，所述第四薄膜晶体管T4的第一端与存储电容Cst的第一电极电连接，所述第四薄膜晶体管T4的第二端与驱动薄膜晶体管T1的第一端电连接。第五薄膜晶体管T5的栅极接收第n-1级扫描信号Scan(n-1)，第五薄膜晶体管T5的第一端接收 数据电压Vdata，第五薄膜晶体管T5的第二端电连接至存储电容Cst的第一电极，从而，存储电容Cst的第一电极经由第五薄膜晶体管T5接收数据电压，经由第四薄膜晶体管T4接收电源电压VDD。在本实施例中，第三薄膜晶体管T3、第四薄膜晶体管T4、第五薄膜晶体管T5、第六薄膜晶体管T6的第一端为源极，第二端为漏极。在本发明的其他实施例中，第三薄膜晶体管、第四薄膜晶体管、第五薄膜晶体管、第六薄膜晶体管的第一端为漏极，第二端为源极。
在本实施例中，开关薄膜晶体管T2、驱动薄膜晶体管T1、第三薄膜晶体管T3、第五薄膜晶体管T5、第六薄膜晶体管T6为P型薄膜晶体管，所述第四薄膜晶体管T4为N型薄膜晶体管。
在本实施例中，OLED驱动电路的OLED发光呈周期性，OLED驱动电路的一个周期包括复位时间段、补偿阈值电压时间段、写入时间段和发光时间，请参见图3，以下结合图2和图3描述OLED驱动电路的驱动。
在本实施例中，在复位时间段，复位信号Reset为低电平，此时，第三薄膜晶体管T3导通，复位电压VI被输送到第一节点B处，也即被输送给驱动薄膜晶体管T1的栅极、存储电容Cst的第二电极、开关薄膜晶体管T2的第一端，从而驱动薄膜晶体管T1栅极的电压Vg＝VI，此时驱动薄膜晶体管T1导通，并且复位电压VI存储在存储电容Cst的第二电极处；同时，在复位时间段，第n-1级扫描信号Scan(n-1)为高电平，从而第四薄膜晶体管T4导通，从而电源电压VDD被输送给存储电容Cst的第一电极，在此处，将第四薄膜晶体管T4与存储电容Cst交接的节点称为A节点，则VA＝VDD，且电源电压VDD存储在存储电容Cst的第一电极处，并且驱动薄膜晶体管T1的第一端的电压等于电源电压VDD，也即Vs＝VDD。
在本实施例中，在补偿阈值电压时间段，第n-1级扫描信号Scan(n-1)仍然为高电平，第四薄膜晶体管T4继续导通，从而，VA＝VDD，Vs＝VDD。同时，第n级扫描信号Scan(n)为低电平，从而，开关薄膜晶体管T2导通，由于在复位时间段驱动薄膜晶体管T1的栅极Vg＝VI，从而驱动薄膜晶体管T1导通，此时开始抓取驱动薄膜晶体管T1的阈值电压Vth，具体为驱动薄膜晶体管T1导通直到驱动薄膜晶体管的栅极和第一端之间的电压与驱动薄膜晶体管T1的阈值电压相同，由于驱动薄膜晶体管T1为P型薄膜晶体管，从而Vsg＝丨Vth 丨，从而抓取到驱动薄膜晶体管T1的阈值电压Vth，此时驱动薄膜晶体管T1截止，也即当所述驱动薄膜晶体管T1的栅极和其第一端之间的电压等于其阈值电压时所述驱动薄膜晶体管T1截止，从而：
Vs-Vg＝丨Vth丨；
Vg＝Vs-丨Vth丨；
Vg＝VDD-丨Vth丨。
在本实施例中，在写入时间段，第n-1级扫描信号Scan(n-1)为低电平，第四薄膜晶体管T4截止，第五薄膜晶体管T5导通，此时存储电容Cst第一电极上的电压由VDD突变为数据电压Vdata，也即VA＝Vdata，通过存储电容Cst的耦合作用，存储电容Cst第二电极上的电压突变为VDD-丨Vth丨-(VDD-Vdata)，从而存储电容Cst第二电极上的电压变为Vdata-丨Vth丨，也即第一节点B处的电压VB＝Vdata-丨Vth丨，从而驱动薄膜晶体管T1栅极上的电压Vg＝Vdata-丨Vth丨，存储在存储电容Cst的第二电极上。
在本实施例中，在发光时间段，使能信号EM转为低电平，从而第六薄膜晶体管T6导通，驱动电流I OLED可通过OLED，OLED发光，此时驱动电流的计算公式如下：
I OLED＝k(Vgs-丨Vth丨) 2
＝k(Vs-Vg-丨Vth丨) 2
＝k(VDD-(Vdata-丨Vth丨)-丨Vth丨) 2
＝k(VDD-Vdata) 2
其中，K为驱动薄膜晶体管T1的电流放大系数，VDD为电源电压，Vdata为数据电压。
从而，通过上面驱动电流I OLED计算公式可知，由于公式中没有驱动薄膜晶体管的阈值电压Vth，从而可以消除驱动薄膜晶体管T1的阈值电压Vth的漂移对驱动电流I OLED的影响，从而驱动电流I OLED比较稳定，从而OLED的发光亮度比较均匀，AMOLED显示面板的画质较好。而且可改善复位时间段中OLED“偸亮”的问题。
另外，在本发明的其他实施例中，开关薄膜晶体管T2、驱动薄膜晶体管T1、第三薄膜晶体管T3、第五薄膜晶体管T5、第六薄膜晶体管T6为N型薄膜 晶体管，所述第四薄膜晶体管T4为P型薄膜晶体管。此时，复位信号Reset、第n-1级扫描信号Scan(n-1)、第n级扫描信号Scan(n)、使能信号EM的电压需要反转，也即图3中的高低电平位置需要颠倒。
本实施例还提供了一种AMOLED显示面板，包括上述的OLED驱动电路。
另外，从上面的计算公式可知，驱动电流I OLED与电源电压VDD相关，而远离电源电压VDD的OLED接收电源电压VDD时，电源电压VDD需要经过长距离传输，而导致电源电压VDD会有降低，从而导致驱动电流I OLED会出现偏差，也即出现本领域普通技术人员熟知的IR drop问题，为了改善该问题，本发明描述第二实施例。
第二实施例
图4是本发明第二实施例OLED驱动电路的示意图，图4的电路与图2的电路相似，因此相同的原件符号代表相同的元器件。本实施例与第一实施例的主要不同点为所述消除模块。
请参见图4，在本实施例中，消除模块还包括第七薄膜晶体管T7和第八薄膜晶体管T8，驱动薄膜晶体管T1的第一端经由第七薄膜晶体管T7接收电源电压VDD。具体说来，第七薄膜晶体管T7的栅极接收使能信号EM，第七薄膜晶体管T7的第一端接收电源电压VDD，第七薄膜晶体管T7的第二端电连接到驱动薄膜晶体管T1的第一端。第八薄膜晶体管T8的栅极接收第n级扫描信号Scan(n)，第八薄膜晶体管T8的第一端接收参考电压Vref，第八薄膜晶体管T8的第二端电连接到驱动薄膜晶体管T1的第一端。另外，在本实施例中，所述重置信号Pro即为所述使能信号EM，两个信号完全相同。在本实施例中，第七薄膜晶体管T7、第八薄膜晶体管T8的第一端为源极，第二端为漏极。在本发明的其他实施例中，第七薄膜晶体管、第八薄膜晶体管的第一端为漏极，第二端为源极。
在本实施例中，开关薄膜晶体管T2、驱动薄膜晶体管T1、第三薄膜晶体管T3、第四薄膜晶体管T4、第五薄膜晶体管T5、第六薄膜晶体管T6、第七薄膜晶体管T7、第八薄膜晶体管T8均为P型薄膜晶体管。
在本实施例中，OLED驱动电路的OLED发光呈周期性，OLED驱动电路的一 个周期包括复位时间段R、补偿阈值电压时间段T、写入时间段W和发光时间E，请参见图5，以下结合图4和图5描述OLED驱动电路的驱动。
在本实施例中，在复位时间段R，复位信号Reset为低电平，此时，第三薄膜晶体管T3导通，复位电压VI被输送给第一节点B处，VB＝VI，复位电压VI会被输送给驱动薄膜晶体管T1的栅极、存储电容Cst的第二电极、开关薄膜晶体管T2的第一端，从而驱动薄膜晶体管T1栅极的电压Vg＝VI，并且复位电压VI存储在存储电容Cst的第二电极处；同时，在复位时间段，第n-1级扫描信号Scan(n-1)为低电平，第五薄膜晶体管T5导通，从而，数据电压Vdata被输送到存储电容Cst的第一电极，在此处，将第四薄膜晶体管T4、第五薄膜晶体管T5与存储电容Cst交接的节点称为A节点,则VA＝Vdata，且数据电压Vdata存储在存储电容Cst的第一电极处。
在本实施例中，在补偿阈值电压时间段T，第n-1级扫描信号Scan(n-1)仍然为低电平，第五薄膜晶体管T5继续导通，从而，VA＝Vdata。同时，第n级扫描信号Scan(n)为低电平，从而，开关薄膜晶体管T2和第八薄膜晶体管T8导通，第八薄膜晶体管T8导通时，驱动薄膜晶体管T1的第一端接收参考电压，由于驱动薄膜晶体管T1的栅极电压保持为复位电压，也即Vg＝VI，此时驱动薄膜晶体管T1导通，由于开关薄膜晶体管T2导通，从而开始抓取驱动薄膜晶体管T1的阈值电压Vth，驱动薄膜晶体管T1导通直到驱动薄膜晶体管的栅极和第一端之间的电压与驱动薄膜晶体管T1的阈值电压Vth相同，由于驱动薄膜晶体管T1为P型薄膜晶体管，从而Vsg＝丨Vth丨，从而抓取到驱动薄膜晶体管T1的阈值电压，此时驱动薄膜晶体管T1截止，也即当所述驱动薄膜晶体管T1的栅极和其第一端之间的电压等于其阈值电压时所述驱动薄膜晶体管T1截止，从而：
Vs-Vg＝丨Vth丨；
Vg＝Vs-丨Vth丨；
Vg＝Vref-丨Vth丨。
在本实施例中，在写入时间段W和发光时间段E，OLED驱动电路接收的信号相同，使能信号EM为低电平，第四薄膜晶体管T4、第六薄膜晶体管T6、第七薄膜晶体管T7导通，第n-1级扫描信号Scan(n-1)为高电平，第五薄膜 晶体管T5截止，此时，存储电容Cst的第一电极突变为电源电压VDD，也即VA＝VDD，通过存储电容Cst的耦合作用，从而存储电容Cst的第二电极上的电压为Vref-丨Vth丨+(VDD-Vdata)，该电压存储在存储电容Cst的第二电极上，也即第一节点B处的电压VB＝Vref-丨Vth丨+(VDD-Vdata)。此时第六薄膜晶体管T6、第七薄膜晶体管T7、驱动薄膜晶体管T1导通，此时，驱动薄膜晶体管T1的第一端的电压也为电源电压VDD，也即Vs＝VDD，同时，OLED上的驱动电流I OLED的计算公式如下：
I OLED＝k(Vgs-丨Vth丨) 2
＝k(Vs-Vg-丨Vth丨) 2
＝k(VDD-(Vref-丨Vth丨+(VDD-Vdata))-丨Vth丨) 2
＝k(Vdata-Vref) 2
其中，k为驱动薄膜晶体管T1的电流放大系数，Vdata为数据电压，Vref为参考电压。
从而，通过上面计算驱动电流I OLED的公式可知，由于公式中没有驱动薄膜晶体管的阈值电压Vth，从而可以消除驱动薄膜晶体管T1的阈值电压的漂移对驱动电流I OLED的影响，从而驱动电流比较稳定，从而OLED的发光亮度比较均匀，AMOLED显示面板的画质较好。而且可改善复位过程中OLED“偸亮”的问题。而且，由于驱动电流I OLED的公式中也没有电源电压VDD，从而，电源电压VDD即使经过长距离传输而导致电源电压VDD的降低，也不会出现IR drop的问题，从而驱动电流更加稳定，从而OLED发光更加稳定。
在本发明的其他实施例中，开关薄膜晶体管、驱动薄膜晶体管、第三薄膜晶体管、第四薄膜晶体管、第五薄膜晶体管、第六薄膜晶体管、第七薄膜晶体管、第八薄膜晶体管均为N型薄膜晶体管。此时，复位信号、第n-1级扫描信号、第n级扫描信号、使能信号的电压需要反转，也即图5中的高低电平位置需要颠倒。
需要说明的是，本说明书中的各个实施例均采用递进的方式描述，每个实施例重点说明的都是与其它实施例的不同之处，各个实施例之间相同相似的部分互相参见即可。对于装置实施例而言，由于其与方法实施例基本相似，所以 描述的比较简单，相关之处参见方法实施例的部分说明即可。
通过上述实施例的描述，本发明具有以下优点：
由于所述OLED驱动电路还包括第三薄膜晶体管、第六薄膜晶体管、消除模块，三者共同用于消除由于所述驱动薄膜晶体管的阈值电压的漂移而带来的流经所述OLED的驱动电流的变化。由于第三薄膜晶体管、第六薄膜晶体管、消除模块的设置，所述驱动电流的计算公式中没有驱动薄膜晶体管的阈值电压，从而可以消除驱动薄膜晶体管的阈值电压的漂移对驱动电流的影响，从而驱动电流比较稳定，OLED的发光亮度比较均匀，AMOLED显示面板的画质较好。
以上所揭露的仅为本发明较佳实施例而已，当然不能以此来限定本发明之权利范围，因此依本发明权利要求所作的等同变化，仍属本发明所涵盖的范围。

Claims (20)

  1. 一种OLED驱动电路，其中，包括：
    开关薄膜晶体管，所述开关薄膜晶体管的栅极接收扫描信号，所述开关薄膜晶体管的第一端电连接到第一节点，所述开关薄膜晶体管的第二端电连接到第二节点；
    驱动薄膜晶体管，所述驱动薄膜晶体管的第一端接收电源电压，所述驱动薄膜晶体管的栅极电连接所述第一节点，所述驱动薄膜晶体管的第二端电连接所述第二节点；
    存储电容，所述存储电容的第一电极接收数据电压，所述存储电容的第二电极连接到第一节点；
    第三薄膜晶体管，其栅极接收复位信号，其第一端接收复位电压，其第二端电连接第一节点；
    第六薄膜晶体管，其栅极接收使能信号，其第一端电连接第二节点；
    OLED，所述OLED的正极电连接所述第六薄膜晶体管的第二端，所述OLED的负极加载低电平电压；
    消除模块，其分别与存储电容的第一电极、驱动薄膜晶体管的第一端电连接，所述消除模块分别接收数据电压和电源电压，所述消除模块、第三薄膜晶体管、第六薄膜晶体管共同用于消除由于所述驱动薄膜晶体管的阈值电压的漂移而导致的所述OLED的驱动电流的变化。
  2. 如权利要求1所述的OLED驱动电路，其中，所述扫描信号是第n级扫描信号，其中n为大于或等于2的整数。
  3. 如权利要求2所述的OLED驱动电路，其中，所述消除模块包括第四薄膜晶体管和第五薄膜晶体管，其中，所述第四薄膜晶体管的栅极接收重置信号，其第一端与存储电容的第一电极电连接，其第二端与驱动薄膜晶体管的第一端电连接，所述第五薄膜晶体管的栅极接收第n-1级扫描信号，第一端接收数据电压，第二端电连接至存储电容的第一电极。
  4. 如权利要求3所述的OLED驱动电路，其中，所述重置信号与所述第n-1级扫描信号相同，其中，
    在复位时间段，所述第三薄膜晶体管和第四薄膜晶体管导通，所述存储电容的第一电极存储电源电压，第二电极存储复位电压，所述驱动薄膜晶体管导通；
    在补偿阈值电压时间段，所述第四薄膜晶体管继续导通，所述开关薄膜晶体管导通，当所述驱动薄膜晶体管的栅极和其第一端之间的电压等于其阈值电压时所述驱动薄膜晶体管截止；
    在写入时间段，所述第五薄膜晶体管导通，所述数据电压输送到存储电容的第一电极；
    在发光时间段，所述第六薄膜晶体管导通，所述OLED发光。
  5. 如权利要求4所述的OLED驱动电路，其中，所述开关薄膜晶体管、驱动薄膜晶体管、第三薄膜晶体管、第五薄膜晶体管、第六薄膜晶体管为P型薄膜晶体管，所述第四薄膜晶体管为N型薄膜晶体管。
  6. 如权利要求3所述的OLED驱动电路，其中，所述消除模块还包括第七薄膜晶体管和第八薄膜晶体管，所述驱动薄膜晶体管的第一端经由所述第七薄膜晶体管接收电源电压，其中，所述第七薄膜晶体管的栅极接收使能信号，其第一端接收电源电压，其第二端电连接驱动薄膜晶体管的第一端，所述第八薄膜晶体管的栅极接收第n级扫描信号，其第一端接收参考电压，其第二端电连接到驱动薄膜晶体管的第一端。
  7. 如权利要求6所述的OLED驱动电路，其中，所述重置信号与所述使能信号相同，其中，
    在复位时间段，所述第三薄膜晶体管和第五薄膜晶体管导通，所述存储电容的第一电极存储数据电压，第二电极存储复位电压；
    在补偿阈值电压时间段，所述第五薄膜晶体管继续导通，所述开关薄膜晶 体管和所述第八薄膜晶体管导通，所述驱动薄膜晶体管开始时导通，当所述驱动薄膜晶体管的栅极和其第一端之间的电压等于其阈值电压时所述驱动薄膜晶体管截止；
    在写入时间段和发光时间段，所述第七薄膜晶体管、第四薄膜晶体管、第六薄膜晶体管导通，所述OLED发光。
  8. 如权利要求7所述的OLED驱动电路，其中，所述开关薄膜晶体管、驱动薄膜晶体管、第三薄膜晶体管、第四薄膜晶体管、第五薄膜晶体管、第六薄膜晶体管、第七薄膜晶体管和第八薄膜晶体管均为P型薄膜晶体管。
  9. 如权利要求4所述的OLED驱动电路，其中，所述复位时间段、补偿阈值电压时间段、写入时间段和发光时间段包含在OLED驱动电路的一个周期内。
  10. 如权利要求7所述的OLED驱动电路，其中，所述复位时间段、补偿阈值电压时间段、写入时间段和发光时间段包含在OLED驱动电路的一个周期内。
  11. 如权利要求1所述的OLED驱动电路，其中，所述第一端为源极，所述第二端为漏极；或者，所述第一端为漏极，所述第二端为源极。
  12. 一种AMOLED显示面板，其中，所述AMOLED显示面板包括OLED驱动电路，所述OLED驱动电路包括：
    开关薄膜晶体管，所述开关薄膜晶体管的栅极接收扫描信号，所述开关薄膜晶体管的第一端电连接到第一节点，所述开关薄膜晶体管的第二端电连接到第二节点；
    驱动薄膜晶体管，所述驱动薄膜晶体管的第一端接收电源电压，所述驱动薄膜晶体管的栅极电连接所述第一节点，所述驱动薄膜晶体管的第二端电连接所述第二节点；
    存储电容，所述存储电容的第一电极接收数据电压，所述存储电容的第二 电极连接到第一节点；
    第三薄膜晶体管，其栅极接收复位信号，其第一端接收复位电压，其第二端电连接第一节点；
    第六薄膜晶体管，其栅极接收使能信号，其第一端电连接第二节点；
    OLED，所述OLED的正极电连接所述第六薄膜晶体管的第二端，所述OLED的负极加载低电平电压；
    消除模块，其分别与存储电容的第一电极、驱动薄膜晶体管的第一端电连接，所述消除模块分别接收数据电压和电源电压，所述消除模块、第三薄膜晶体管、第六薄膜晶体管共同用于消除由于所述驱动薄膜晶体管的阈值电压的漂移而导致的所述OLED的驱动电流的变化。
  13. 如权利要求12所述的AMOLED显示面板，其中，所述扫描信号是第n级扫描信号，其中n为大于或等于2的整数。
  14. 如权利要求13所述的AMOLED显示面板，其中，所述消除模块包括第四薄膜晶体管和第五薄膜晶体管，其中，所述第四薄膜晶体管的栅极接收重置信号，其第一端与存储电容的第一电极电连接，其第二端与驱动薄膜晶体管的第一端电连接，所述第五薄膜晶体管的栅极接收第n-1级扫描信号，第一端接收数据电压，第二端电连接至存储电容的第一电极。
  15. 如权利要求14所述的AMOLED显示面板，其中，所述重置信号与所述第n-1级扫描信号相同，其中，
    在复位时间段，所述第三薄膜晶体管和第四薄膜晶体管导通，所述存储电容的第一电极存储电源电压，第二电极存储复位电压，所述驱动薄膜晶体管导通；
    在补偿阈值电压时间段，所述第四薄膜晶体管继续导通，所述开关薄膜晶体管导通，当所述驱动薄膜晶体管的栅极和其第一端之间的电压等于其阈值电压时所述驱动薄膜晶体管截止；
    在写入时间段，所述第五薄膜晶体管导通，所述数据电压输送到存储电容 的第一电极；
    在发光时间段，所述第六薄膜晶体管导通，所述OLED发光。
  16. 如权利要求15所述的AMOLED显示面板，其中，所述开关薄膜晶体管、驱动薄膜晶体管、第三薄膜晶体管、第五薄膜晶体管、第六薄膜晶体管为P型薄膜晶体管，所述第四薄膜晶体管为N型薄膜晶体管。
  17. 如权利要求14所述的AMOLED显示面板，其中，所述消除模块还包括第七薄膜晶体管和第八薄膜晶体管，所述驱动薄膜晶体管的第一端经由所述第七薄膜晶体管接收电源电压，其中，所述第七薄膜晶体管的栅极接收使能信号，其第一端接收电源电压，其第二端电连接驱动薄膜晶体管的第一端，所述第八薄膜晶体管的栅极接收第n级扫描信号，其第一端接收参考电压，其第二端电连接到驱动薄膜晶体管的第一端。
  18. 如权利要求17所述的AMOLED显示面板，其中，所述重置信号与所述使能信号相同，其中，
    在复位时间段，所述第三薄膜晶体管和第五薄膜晶体管导通，所述存储电容的第一电极存储数据电压，第二电极存储复位电压；
    在补偿阈值电压时间段，所述第五薄膜晶体管继续导通，所述开关薄膜晶体管和所述第八薄膜晶体管导通，所述驱动薄膜晶体管开始时导通，当所述驱动薄膜晶体管的栅极和其第一端之间的电压等于其阈值电压时所述驱动薄膜晶体管截止；
    在写入时间段和发光时间段，所述第七薄膜晶体管、第四薄膜晶体管、第六薄膜晶体管导通，所述OLED发光。
  19. 如权利要求18所述的AMOLED显示面板，其中，所述开关薄膜晶体管、驱动薄膜晶体管、第三薄膜晶体管、第四薄膜晶体管、第五薄膜晶体管、第六薄膜晶体管、第七薄膜晶体管和第八薄膜晶体管均为P型薄膜晶体管。
  20. 如权利要求15所述的AMOLED显示面板，其中，所述复位时间段、补偿阈值电压时间段、写入时间段和发光时间段包含在OLED驱动电路的一个周期内。
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