CN113077754A - Pixel driving circuit - Google Patents

Pixel driving circuit Download PDF

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Publication number
CN113077754A
CN113077754A CN202110393850.2A CN202110393850A CN113077754A CN 113077754 A CN113077754 A CN 113077754A CN 202110393850 A CN202110393850 A CN 202110393850A CN 113077754 A CN113077754 A CN 113077754A
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switch
control
control signal
period
capacitor
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CN113077754B (en
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林志隆
廖威胜
吴佳恩
陈松骏
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AU Optronics Corp
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AU Optronics Corp
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    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
    • G09G3/30—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels
    • G09G3/32—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED]
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—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 by control of light from an independent source
    • G09G3/3406—Control of illumination source
    • 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

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Control Of Indicators Other Than Cathode Ray Tubes (AREA)
  • Electroluminescent Light Sources (AREA)

Abstract

The invention provides a pixel driving circuit, which comprises a light-emitting unit, twelve switches and three capacitors. The driving current of the light emitting unit only flows through one of the switches, thereby saving power consumption. In addition, the pixel driving circuit can compensate the critical voltage and the operating voltage, so that the light-emitting unit can provide consistent brightness.

Description

Pixel driving circuit
Technical Field
The present disclosure relates to a pixel driving circuit of a light emitting diode.
Background
Light emitting diodes are widely used in various types of displays. The brightness of the light emitting diode during light emission is related to the magnitude of the driving current thereof, and the magnitude of the driving current is controlled by the driving transistor. However, the threshold voltage (Vth) of the driving transistor of each pixel in the display is different due to process variation, so that the leds in different pixels have different driving currents and the brightness of each led is different, thereby causing the display to have a non-uniform brightness when displaying images. In addition, the driving current is provided by the operating voltage, and the operating voltage is likely to generate a voltage drop due to the line resistance in the transmission path, so that the operating voltage of each pixel is different, and the driving current generates an error.
Therefore, it is an objective of research by those skilled in the art to compensate for the threshold voltage of the driving transistor of a pixel of a display and also compensate for the operating voltage.
Disclosure of Invention
An embodiment of the present invention provides a pixel driving circuit, which includes the following components. The light emitting unit has a first end and a second end, and the first end of the light emitting unit is connected to a first operating voltage. The first switch has a first end, a second end and a control end, the first end of the first switch is connected to the second end of the light-emitting unit, and the second end of the first switch is connected to the second operating voltage. The second switch is provided with a first end, a second end and a control end, the first end of the second switch is connected to the control end of the first switch, the second end of the second switch is connected to the second end of the first switch and the second operating voltage, and the control end of the second switch is connected to the first control signal. The first capacitor has a first end and a second end, and the first end of the first capacitor is connected to the control end of the first switch and the first end of the second switch. The second capacitor has a first end and a second end, the first end of the second capacitor is connected to the second end of the first capacitor, and the second end of the second capacitor is connected to a reference voltage. The third switch has a first end, a second end and a control end, the first end of the third switch is connected to the control end of the first switch, the first end of the second switch and the first end of the first capacitor, and the control end of the third switch is connected to the second control signal. The fourth switch has a first end, a second end and a control end, the first end of the fourth switch is connected to the control end of the fourth switch, and the second end of the fourth switch is connected to the reference voltage. The fifth switch has a first end, a second end and a control end, the first end of the fifth switch is connected to the second end of the first switch and the second end of the second switch, and the second end of the fifth switch is connected to the second end of the first capacitor and the first end of the second capacitor. The sixth switch has a first end, a second end and a control end, the first end of the sixth switch is connected to the second end of the fifth switch, the second end of the first capacitor and the first end of the second capacitor, the second end of the sixth switch is connected to the diode voltage, and the control end of the sixth switch is connected to the third control signal. The seventh switch has a first end, a second end and a control end, the first end of the seventh switch is connected to the control end of the fifth switch, the second end of the seventh switch is connected to the diode voltage, and the control end of the seventh switch is connected to the third control signal. The eighth switch has a first end, a second end and a control end, and the first end of the eighth switch is connected to the control end of the fifth switch and the first end of the seventh switch. The third capacitor has a first end and a second end, the first end of the third capacitor is connected to the second end of the eighth switch, and the second end of the third capacitor is connected to the reference voltage. The ninth switch has a first end, a second end and a control end, the first end of the ninth switch is connected to the first end of the third capacitor and the second end of the eighth switch, the second end of the ninth switch is connected to the first control signal, and the control end of the ninth switch is connected to the first control signal. The tenth switch has a first end, a second end and a control end, the first end of the tenth switch is connected to the second end of the eighth switch, the first end of the third capacitor and the first end of the ninth switch, the second end of the tenth switch is connected to the control end of the eighth switch, and the control end of the tenth switch is connected to the first control signal. The eleventh switch has a first end, a second end and a control end, the first end of the eleventh switch is connected to the control end of the eighth switch and the second end of the tenth switch, the second end of the eleventh switch is connected to the fourth control signal, and the control end of the eleventh switch is connected to the third control signal. The twelfth switch has a first end, a second end and a control end, the first end of the twelfth switch is connected to the control end of the eighth switch, the second end of the tenth switch and the first end of the eleventh switch, the second end of the twelfth switch is connected to a data voltage, and the control end of the twelfth switch is connected to the second control signal.
In some embodiments, the pixel driving circuit operates in a first period, a second period, a third period, and a fourth period in sequence. In the first period, the second switch, the fourth switch, the sixth switch, the seventh switch, the ninth switch and the tenth switch are in a conducting state, and the first switch, the third switch, the fifth switch, the eighth switch, the eleventh switch and the twelfth switch are in a non-conducting state. In the second period, the third switch, the fourth switch, the sixth switch, the seventh switch, the eighth switch, and the twelfth switch are turned on, and the first switch, the second switch, the fifth switch, the ninth switch, the tenth switch, and the eleventh switch are turned off. In the first sub-period of the third period, the eleventh switch is in an on state, and the first to third switches, the fifth to tenth switches, and the twelfth switch are in an off state. In a second sub-period of the third period, the first switch, the fifth switch, the eighth switch, and the eleventh switch are in an on state, and the second switch, the third switch, the sixth switch, the seventh switch, the ninth switch, the tenth switch, and the twelfth switch are in an off state. In the fourth period, the sixth switch and the seventh switch are in the on state, and the first switch, the second switch, the third switch, the fifth switch, the eighth switch to the twelfth switch are in the off state.
In some embodiments, the eighth switch and the eleventh switch are P-type transistors, and the first to seventh switches, the ninth switch, the tenth switch and the twelfth switch are N-type transistors.
In some embodiments, the threshold voltage of the first switch is matched to the threshold voltage of the fourth switch.
In some embodiments, during the first period, the first control signal and the third control signal are at a first high level, the second control signal is at a first low level, and the fourth control signal is at a second high level. In the second period, the first control signal is at a first low level, the second control signal and the third control signal are at a first high level, and the fourth control signal is at a second high level. In the third period, the first control signal, the second control signal and the third control signal are at the first low level, and the fourth control signal is gradually reduced from the second high level to the second low level. In the fourth period, the first control signal and the second control signal are at the first low level, the third control signal is at the first high level, and the fourth control signal is at the second high level.
In some embodiments, the first operating voltage is greater than the second operating voltage.
In some embodiments, the light emitting unit is a light emitting diode.
In some embodiments, the size of the light emitting diode is sub-millimeter.
In some embodiments, the pixel driving circuit is disposed in the display panel.
In some embodiments, the pixel driving circuit is disposed in the backlight module.
In the pixel driving circuit, the threshold voltage and the operating voltage can be compensated, and the technical effect of saving power consumption is achieved.
Drawings
In order to make the aforementioned and other features and advantages of the invention more comprehensible, embodiments accompanied with figures are described in detail below.
Fig. 1 is a circuit architecture diagram illustrating a pixel driving circuit according to an embodiment.
Fig. 2 is a timing diagram illustrating various control signals in the pixel driving circuit according to one embodiment.
Fig. 3 is a switching schematic diagram illustrating a pixel driving circuit during a first period according to an embodiment.
Fig. 4 is a switching diagram illustrating a pixel driving circuit during a second period according to an embodiment.
Fig. 5 is a switching diagram illustrating a pixel driving circuit in a first sub-period during a third period according to an embodiment.
Fig. 6 is a switching diagram illustrating a pixel driving circuit during a second sub-period in a third period according to an embodiment.
FIG. 7 is a switching diagram illustrating a pixel drive circuit during a fourth period according to one embodiment.
Description of reference numerals:
100: pixel driving circuit
110: light emitting unit
C1: first capacitor
C2: second capacitor
C3: third capacitor
T1-T12: switch with a switch body
ILED: electric current
110-1, C1-1, C2-1, C3-1, T1-1, T2-1, T3-1, T4-1, T5-1, T6-1, T7-1, T8-1, T9-1, T10-1, T11-1, T12-1: first end
110-2, C1-2, C2-2, C3-2, T1-2, T2-2, T3-2, T4-2, T5-2, T6-2, T7-2, T8-2, T9-2, T10-2, T11-2, T12-2: second end
T1-3, T2-3, T3-3, T4-3, T5-3, T6-3, T7-3, T8-3, T9-3, T10-3, T11-3, T12-3: control terminal
A, B, C, D, E: node point
VDD, VSS: operating voltage
S1,S2,EM,Vsweep: control signal
VDATA: data voltage
VLED: voltage of the diode
Vref: reference voltage
210: the first period
220: the second period
230: the third period
230-1: the first sub-period
230-2: the second sub-period
240: the fourth period
VGH,Vsweep_H: high level
VGL,Vsweep_L: low level of electricity
Detailed Description
As used herein, the terms "first," "second," and the like, do not denote any particular order or order, but rather are used to distinguish one element from another or from another.
Fig. 1 is a circuit architecture diagram illustrating a pixel driving circuit according to an embodiment. The pixel driving circuit 100 may be disposed on a backlight module of a display device to provide a backlight source, or disposed in a display panel as a pixel, which is not limited in this disclosure. The pixel driving circuit 100 includes a light emitting unit 110, switches T1-T12, a first capacitor C1, a second capacitor C2, and a third capacitor C3. The light emitting unit 110 is, for example, a light emitting diode, and the size of the light emitting diode may be on the sub-millimeter scale or other suitable size, which is not limited in this disclosure.
The light emitting unit 110 has a first terminal 110-1 and a second terminal 110-2, and the first terminal 110-1 of the light emitting unit 110 is connected to an operating voltage VDD. The switch T1 has a first terminal T1-1, a second terminal T1-2 and a control terminal T1-3, wherein the first terminal T1-1 of the switch T1 is connected to the second terminal 110-2 of the light emitting unit 110, and the second terminal T1-2 of the switch T1 is connected to an operating voltage VSS, wherein the operating voltage VSS is less than the operating voltage VSS. The switch T2 has a first terminal T2-1, a second terminal T2-2 and a control terminal T2-3, the first terminal T2-1 of the switch T2 is connected to the control terminal T1-3 of the switch T1, the second terminal T2-2 of the switch T2 is connected to the second terminal T1-2 of the switch T1 and the operation voltage VSS, and the control terminal T2-3 of the switch T2 is connected to the control signal S1. The first capacitor C1 has a first terminal C1-1 and a second terminal C1-2, and the first terminal C1-1 of the first capacitor C1 is connected to the control terminal T1-3 of the switch T1 and the first terminal T2-1 of the switch T2. The second capacitor C2 has a first terminal C2-1 and a second terminal C2-2, the first terminal C2-1 of the second capacitor C2 is connected to the second terminal C1-2 of the first capacitor C1, and the second terminal C2-2 of the second capacitor C2 is connected to a reference voltage Vref. The switch T3 has a first terminal T3-1, a second terminal T3-2 and a control terminal T3-3, the first terminal T3-1 of the switch T3 is connected to the control terminal T1-3 of the switch T1, the first terminal T2-1 of the switch T2 and the first terminal C1-1 of the first capacitor C1, and the control terminal T3-3 of the switch T3 is connected to the control signal S2. The switch T4 has a first terminal T4-1, a second terminal T4-2, a control terminal T4-3, a third terminal of the switch T4One terminal T4-1 is connected to the control terminal T4-3 of the switch T4, and the second terminal T4-2 of the switch T4 is connected to the reference voltage Vref. The switch T5 has a first terminal T5-1, a second terminal T5-2 and a control terminal T5-3, the first terminal T5-1 of the switch T5 is connected to the second terminal T1-2 of the switch T1 and the second terminal T2-2 of the switch T2, and the second terminal T5-2 of the switch T5 is connected to the second terminal C1-2 of the first capacitor C1 and the first terminal C2-1 of the second capacitor C2. The switch T6 has a first terminal T6-1, a second terminal T6-2 and a control terminal T6-3, the first terminal T6-1 of the switch T6 is connected to the second terminal T5-2 of the switch T5, the second terminal C1-2 of the first capacitor C1 and the first terminal C2-1 of the second capacitor C2, and the second terminal T6-2 of the switch T6 is connected to a diode voltage VLEDThe control terminal T6-3 of the switch T6 is connected to the control signal EM.
The switch T7 has a first terminal T7-1, a second terminal T7-2 and a control terminal T7-3, the first terminal T7-1 of the switch T7 is connected to the control terminal T5-3 of the switch T5, and the second terminal T7-2 of the switch T7 is connected to the diode voltage VLEDThe control terminal T7-3 of the switch T7 is connected to the control signal EM. The switch T8 has a first terminal T8-1, a second terminal T8-2 and a control terminal T8-3, and the first terminal T8-1 of the switch T8 is connected to the control terminal T5-3 of the switch T5 and the first terminal T7-1 of the switch T7. The third capacitor C3 has a first terminal C3-1 and a second terminal C3-2, the first terminal C3-1 of the third capacitor C3 is connected to the second terminal T8-2 of the switch T8, and the second terminal C3-2 of the third capacitor C3 is connected to the reference voltage Vref. The switch T9 has a first terminal T9-1, a second terminal T9-2 and a control terminal T9-3, the first terminal T9-1 of the switch T9 is connected to the first terminal C3-1 of the third capacitor C3 and the second terminal T8-2 of the switch T8, the second terminal T9-2 of the switch T9 is connected to the control signal S1, and the control terminal T9-3 of the switch T9 is connected to the control signal S1. The switch T10 has a first terminal T10-1, a second terminal T10-2 and a control terminal T10-3, the first terminal T10-1 of the switch T10 is connected to the second terminal T8-2 of the switch T8, the first terminal C3-1 of the third capacitor C3 and the first terminal T9-1 of the switch T9, the second terminal T10-2 of the switch T10 is connected to the control terminal T8-3 of the switch T8, and the control terminal T10-3 of the switch T10 is connected to the control signal S1. The switch T11 has a first terminal T11-1, a second terminal T11-2 and a control terminal T11-3, the first terminal T11-1 of the switch T11 is connected to the control terminal T8-3 of the switch T8 and the second terminal T10-2 of the switch T10, the second terminal T11-2 of the switch T11 is connected to the control signal VsweepThe control terminal T11-3 of the switch T11 is connected to the control signal EM. The switch T12 has a first terminal T12-1, a second terminal T12-2 and a control terminal T12-3, the first terminal T12-1 of the switch T12 is connected to the control terminal T8-3 of the switch T8, the second terminal T10-2 of the switch T10 and the first terminal T11-1 of the switch T11, the second terminal T12-2 of the switch T12 is connected to the data voltage VDATAThe control terminal T12-3 of the switch T12 is connected to the control signal S2.
In this embodiment, the switches T1 to T12 are, for example, thin film transistors (thin film transistors), wherein the switches T8 and T11 are P-type transistors, and the switches T1 to T7, T9, T10 and T12 are N-type transistors. In addition, the threshold voltage of the switch T1 is matched to the threshold voltage of the switch T4, and the technical effect of threshold voltage matching will be described in detail below.
Fig. 2 is a timing diagram illustrating various control signals in the pixel driving circuit according to one embodiment. Referring to fig. 2, the pixel driving circuit operates in the first period 210, the second period 220, the third period 230 and the fourth period 240 in sequence, and returns to the first period 210 after the fourth period 240 is finished.
Fig. 3 is a switching schematic diagram illustrating a pixel driving circuit during a first period according to an embodiment. Referring to fig. 2 and 3, the first period 210 is used to reset the pixel driving circuit 100. During the first period 210, the control signal S1 and the control signal EM are at the high level VGHThe control signal S2 is at a low level VGLControl signal VsweepAt a high level Vsweep_HWherein the high level VGHMay or may not be the same as the high level Vsweep_HThe disclosure is not so limited. Therefore, the switches T2, T4, T6, T7, T9, and T10 are in an on state, and the switches T1, T3, T5, T8, T11, and T12 are in an off state. During the first period 210, the potential of the node a is the same as the reference voltage VSS. The potentials of the node B and the node C are the same as the diode voltage VLED. The potentials of the nodes D and E are the same as the high level VGH。
Fig. 4 is a switching diagram illustrating a pixel driving circuit during a second period according to an embodiment. Referring to fig. 2 and 4, the second period 220 is used for voltage compensation. During the second period 220, the control signal S1 is lowVGLThe control signal S2 and the control signal EM are at a high level VGHControl signal VsweepAt a high level Vsweep_H. Therefore, the switches T3, T4, T6, T7, T8, and T12 are in an on state, and the switches T1, T2, T5, T9, T10, and T11 are in an off state. During this period, the potential of the node A is the same as Vref+VTH_T4In which V isTH_T4Is the threshold voltage of switch T4. The potentials of the node B and the node C are the same as the diode voltage VLED. The potential of the node D is the same as the data voltage VDATA. The potential of the node E will increase due to the charging of the third capacitor C3 until the potential of the node E is equal to VDATA+|VTH_T8| time switch T8 switches to the OFF state, where VTH_T8Is the threshold voltage of switch T8.
Fig. 5 is a switching diagram illustrating a pixel driving circuit in a first sub-period during a third period according to an embodiment. Referring to fig. 2 and 5, the third period 230 is divided into a first sub-period 230-1 and a second sub-period 230-2, the light emitting unit 110 is turned off in the first sub-period 230-1, and the light emitting unit 110 is turned on and emits light in the second sub-period 230-2. The lengths of the first sub-period 230-1 and the second sub-period 230-2 are determined by the data voltage VDATAAnd (4) determining. In other words, in this embodiment, the light emitting unit 110 is driven by Pulse Width Modulation (PWM), so as to determine the brightness of the pixel. Specifically, in the third period 230, the control signal S1, the control signal S2, and the control signal EM are at the low level VGLControl signal VsweepFrom a high level Vsweep_HGradually decreases to a low level Vsweep_L。
In the first sub-period 230-1, the switch T11 is in the on state, and the switches T1 to T3, T5 to T10, and T12 are in the off state. The potential of the node A is kept constant and is maintained at Vref+VTH_T4. The potentials of the node B and the node C are the same as the diode voltage VLED. The potential of the node D is the same as the control signal Vsweep. The potential of the node E is the same as VDATA+|VTH_T8L. The potential of the node D gradually decreases until the switch T8 is switched to the on state when the following expression 1 holds, and thenThe second sub-period 230-2 is entered.
[ mathematical formula 1]
Figure BDA0003017995130000081
Wherein VEIndicates the potential of the node E, VDIndicating the potential of node D. Since the threshold voltage of the switch T8 is self-compensated, the condition for establishing the above equation 1 is not affected by the threshold voltage of the switch T8. When the data voltage VDATAThe larger the value, the earlier the equation 1 is established, and the earlier the second sub-period 230-2 is entered.
Fig. 6 is a switching diagram illustrating a pixel driving circuit during a second sub-period in a third period according to an embodiment. Referring to fig. 2 and 6, in the second sub-period 230-2, the switches T1, T5, T8 and T11 are in the on state, and the switches T2, T3, T6, T7, T9, T10 and T12 are in the off state. During this period, the potentials of the node E and the node C are the same as VDATA+|VTH_T8This turns on the switch T5, which makes the node B at the operating voltage VSS. The potential of the node B is V from the first sub-period 230-1LEDChange to VSS by an amount of VSS-VLEDSo that the potential of the node A will be from Vref+VTH_T4Change to Vref+VTH_T4+VSS-VLEDThis potential turns on switch T1 to generate current ILEDThe current ILEDA current I flows through the light emitting unit 110 and the switch T1LEDThe size of (d) is shown in the following equation 2.
[ mathematical formula 2]
Figure BDA0003017995130000082
Figure BDA0003017995130000091
Wherein K is a constant, VAIs the potential of node A, VTH_T1Is the adjacent of the switch T1The boundary voltage. It is noted that, since the threshold voltage of the switch T1 is matched to the threshold voltage of the switch T4, two threshold voltages V are shown in the formula 2TH_T4、VTH_T1Mutual offset, current ILEDIs not influenced by the critical voltage VTH_T1The influence of (c). In addition, since the operating voltage VSS is compensated in equation 2, the current ILEDIs also not affected by the operating voltage VSS. In the prior art, when the driving current passes through more than two switches, voltage drop is generated when the current is larger, so that the switches can enter a linear region, and the problem can be solved by increasing the cross voltage between the operating voltages VDD and VSS, but the power consumption is improved. In contrast, the current ILEDOnly one switch T1 will flow, thus having the technical effect of reducing power consumption.
FIG. 7 is a switching diagram illustrating a pixel drive circuit during a fourth period according to one embodiment. Referring to fig. 2 and 7, the fourth period 240 is used to turn off the light emitting unit 110. During the fourth period 240, the control signals S1 and S2 are at a low level VGLControl signal EM is high level VGHControl signal VsweepAt a high level Vsweep_H. Therefore, the switches T6 and T7 are in the on state, and the switches T1, T2, T3, T5, T8 to T12 are in the off state. During this period, the potentials of the node B and the node C are the diode voltage VLED. The potential of the node B changes from VSS of the second sub-period 230-2 to V of the fourth period 240LEDAt a variable amount of VLEDVSS, so that the potential of node A is V of 230-2 during this periodref+VTH_T4+VSS-VLEDChange to Vref+VTH_T4. The potential of the node D is the same as the control signal Vsweep. The potential of the node E is the same as VDATA+|VTH_T8|。
In the above embodiments, "connected" may be a direct connection.
Although the present invention has been described with reference to the above embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention.

Claims (10)

1. A pixel driving circuit comprising:
a light emitting unit having a first end and a second end, the first end of the light emitting unit being connected to a first operating voltage;
a first switch having a first end, a second end and a control end, wherein the first end of the first switch is connected to the second end of the light-emitting unit, and the second end of the first switch is connected to a second operating voltage;
a second switch having a first end, a second end and a control end, wherein the first end of the second switch is connected to the control end of the first switch, the second end of the second switch is connected to the second end of the first switch and the second operating voltage, and the control end of the second switch is connected to the first control signal;
a first capacitor having a first end and a second end, the first end of the first capacitor being connected to the control end of the first switch and the first end of the second switch;
a second capacitor having a first end and a second end, the first end of the second capacitor being connected to the second end of the first capacitor, the second end of the second capacitor being connected to a reference voltage;
a third switch having a first end, a second end and a control end, the first end of the third switch being connected to the control end of the first switch, the first end of the second switch and the first end of the first capacitor, the control end of the third switch being connected to a second control signal;
a fourth switch having a first end, a second end and a control end, wherein the first end of the fourth switch is connected to the control end of the fourth switch, and the second end of the fourth switch is connected to the reference voltage;
a fifth switch having a first end, a second end and a control end, wherein the first end of the fifth switch is connected to the second end of the first switch and the second end of the second switch, and the second end of the fifth switch is connected to the second end of the first capacitor and the first end of the second capacitor;
a sixth switch having a first end, a second end, and a control end, wherein the first end of the sixth switch is connected to the second end of the fifth switch, the second end of the first capacitor, and the first end of the second capacitor, the second end of the sixth switch is connected to a diode voltage, and the control end of the sixth switch is connected to a third control signal;
a seventh switch having a first end, a second end, and a control end, wherein the first end of the seventh switch is connected to the control end of the fifth switch, the second end of the seventh switch is connected to the diode voltage, and the control end of the seventh switch is connected to the third control signal;
an eighth switch having a first end, a second end, and a control end, the first end of the eighth switch being connected to the control end of the fifth switch and the first end of the seventh switch;
a third capacitor having a first end and a second end, the first end of the third capacitor being connected to the second end of the eighth switch, the second end of the third capacitor being connected to the reference voltage;
a ninth switch having a first end, a second end and a control end, wherein the first end of the ninth switch is connected to the first end of the third capacitor and the second end of the eighth switch, the second end of the ninth switch is connected to the first control signal, and the control end of the ninth switch is connected to the first control signal;
a tenth switch having a first end, a second end, and a control end, the first end of the tenth switch being connected to the second end of the eighth switch, the first end of the third capacitor, and the first end of the ninth switch, the second end of the tenth switch being connected to the control end of the eighth switch, the control end of the tenth switch being connected to the first control signal;
an eleventh switch having a first end, a second end, and a control end, wherein the first end of the eleventh switch is connected to the control end of the eighth switch and the second end of the tenth switch, the second end of the eleventh switch is connected to a fourth control signal, and the control end of the eleventh switch is connected to the third control signal;
a twelfth switch having a first end, a second end, and a control end, wherein the first end of the twelfth switch is connected to the control end of the eighth switch, the second end of the tenth switch, and the first end of the eleventh switch, the second end of the twelfth switch is connected to a data voltage, and the control end of the twelfth switch is connected to the second control signal.
2. The pixel driving circuit according to claim 1, wherein the pixel driving circuit operates in a first period, a second period, a third period and a fourth period sequentially,
wherein during the first period, the second switch, the fourth switch, the sixth switch, the seventh switch, the ninth switch and the tenth switch are in a conducting state, the first switch, the third switch, the fifth switch, the eighth switch, the eleventh switch and the twelfth switch are in a blocking state,
wherein in the second period, the third switch, the fourth switch, the sixth switch, the seventh switch, the eighth switch and the twelfth switch are in the on state, the first switch, the second switch, the fifth switch, the ninth switch, the tenth switch and the eleventh switch are in the off state,
wherein in a first sub-period of the third period, the eleventh switch is in the on state, the first to third switches, the fifth to tenth switches, and the twelfth switch are in the off state,
wherein in a second sub-period of the third period, the first switch, the fifth switch, the eighth switch and the eleventh switch are in the on state, the second switch, the third switch, the sixth switch, the seventh switch, the ninth switch, the tenth switch and the twelfth switch are in the off state,
in the fourth period, the sixth switch and the seventh switch are in the on state, and the first switch, the second switch, the third switch, the fifth switch, the eighth switch and the twelfth switch are in the off state.
3. The pixel driving circuit according to claim 2, wherein the eighth switch and the eleventh switch are P-type transistors, and the first to seventh switches, the ninth switch, the tenth switch and the twelfth switch are N-type transistors.
4. A pixel driving circuit as claimed in claim 3, wherein the threshold voltage of the first switch is matched to the threshold voltage of the fourth switch.
5. The pixel driving circuit according to claim 3, wherein during the first period, the first control signal and the third control signal are at a first high level, the second control signal is at a first low level, the fourth control signal is at a second high level,
wherein during the second period, the first control signal is at the first low level, the second control signal and the third control signal are at the first high level, the fourth control signal is at the second high level,
wherein during the third period, the first control signal, the second control signal and the third control signal are at the first low level, the fourth control signal gradually decreases from the second high level to a second low level,
in the fourth period, the first control signal and the second control signal are at the first low level, the third control signal is at the first high level, and the fourth control signal is at the second high level.
6. A pixel driving circuit as claimed in claim 5, wherein the first operating voltage is greater than the second operating voltage.
7. The pixel driving circuit as claimed in claim 1, wherein the light emitting unit is a light emitting diode.
8. A pixel driving circuit as claimed in claim 7, wherein the size of the light emitting diode is sub-millimeter.
9. The pixel driving circuit according to claim 1, wherein the pixel driving circuit is disposed in a display panel.
10. The pixel driving circuit as claimed in claim 1, wherein the pixel driving circuit is disposed in a backlight module.
CN202110393850.2A 2020-06-10 2021-04-13 Pixel driving circuit Active CN113077754B (en)

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CN110767151A (en) * 2019-03-21 2020-02-07 友达光电股份有限公司 Light emitting diode display panel
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103854602A (en) * 2012-12-03 2014-06-11 三星显示有限公司 Error compensator and organic light emitting display device using the same
CN103247262A (en) * 2013-04-28 2013-08-14 京东方科技集团股份有限公司 Pixel circuit, driving method of pixel circuit and display device with pixel circuit
CN104064139A (en) * 2014-06-05 2014-09-24 上海天马有机发光显示技术有限公司 OLED (Organic Light Emitting Diodes) pixel compensating circuit, display panel and display device
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