CN114446242B - Pixel circuit, driving method thereof and display panel - Google Patents
Pixel circuit, driving method thereof and display panel Download PDFInfo
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- CN114446242B CN114446242B CN202210358325.1A CN202210358325A CN114446242B CN 114446242 B CN114446242 B CN 114446242B CN 202210358325 A CN202210358325 A CN 202210358325A CN 114446242 B CN114446242 B CN 114446242B
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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]
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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
- 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
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- Control Of Indicators Other Than Cathode Ray Tubes (AREA)
- Electroluminescent Light Sources (AREA)
Abstract
The application discloses a pixel circuit, a driving method thereof and a display panel. The pixel circuit includes: a driving unit connected between a first power supply and a second power supply; the control unit is connected to the driving unit and used for controlling the on-off state of the driving unit; the light-emitting unit is connected to the first power supply through the driving unit, and the light-emitting state of the light-emitting unit is at least controlled by the switching state of the driving unit; and a fuse connected between the driving unit and the first power supply, wherein, in the repair mode, a current flowing through the fuse is configured such that the fuse is blown, thereby cutting a current path between the first power supply and the light emitting unit such that the light emitting unit stops emitting light. The pixel circuit realizes bright spot repair by using the fuse wire, and improves the yield, the accuracy and the efficiency of bright spot repair.
Description
Technical Field
The invention relates to the technical field of display, in particular to a pixel circuit, a driving method thereof and a display panel. .
Background
An Organic Light-Emitting Diode (OLED) is a new display device developed in the middle of the 20 th century. The OLED has the advantages of ultra-light weight, thinness, all solid state, active light emitting, high response speed, high contrast, no visual angle limitation, wide working temperature range, low power consumption, low cost, strong shock resistance, capability of realizing flexible display and the like, and is known as a 'dream display'. The superior performance and the huge market potential of the OLED display attract a plurality of manufacturers and scientific research institutions all over the world to be put into the production and research and development of OLED devices.
Due to the development of AMOLEDs (active matrix organic light emitting diodes), large-sized OLED display screens usually employ TFTs (thin film transistors) to drive the anode for power supply. And for a micro OLED display screen, a CMOS circuit is adopted to complete the driving function. However, due to the limitation of the yield of the manufacturing process, the bottom layer driving circuit has partial dead spots, and the transistor cannot be turned off, so that the OLED has bright spots when displaying a black picture. Especially for some special fields, the bright spot phenomenon of the high brightness OLED device is more severe due to the larger load pressure.
Among the existing solutions for repairing screen bright spots, laser repair is the most common one. The laser repair is to scan a bottom layer driving circuit or an organic functional layer by adopting high-energy laser pulses and completely gasify the layer, so that the direct short circuit of a grid drain or a cathode and an anode is realized, and the short circuit is realized. The method has high control requirement on laser energy, the heat influence is serious due to the excessive energy, and the thermal stress generated by gasification is difficult to release, so that the film defect is caused. Since OLED devices have very high requirements with regard to the compactness of the encapsulation layer, this method is even susceptible to damage of the encapsulation layer, leading to irreversible destruction. Too low energy can cause a small part of organic functional layers to remain, and the change of film thickness and components can cause voltage to be increased, so that the brightness of the device is abnormally increased, and the brightness of bright spots is further increased. The existing laser repair process can only be applied to large-size OLED panels, the pixel size of a micro OLED device reaches the micron level, the distance between pixels is probably smaller than 1um, and the influence of the processing precision, the light spot size, the optical diffraction and other problems of laser repair equipment on the scale is more obvious, so that the stability of the process of an isolation method and the stability of the previous process are a critical problem in actual production. Furthermore, laser repair depends on laser repair equipment, and the cost is high.
It is therefore desirable to provide an improved pixel circuit to address the above problems.
Disclosure of Invention
In view of the above problems, an object of the present invention is to provide a pixel circuit, a driving method thereof, and a display panel, so as to improve the yield, accuracy, and efficiency of bright point repair and reduce the cost.
According to a first aspect of the present invention, there is provided a pixel circuit comprising:
a driving unit connected between a first power supply and a second power supply;
the control unit is connected to the driving unit and used for controlling the on-off state of the driving unit;
the light-emitting unit is connected to the first power supply through the driving unit, and the light-emitting state of the light-emitting unit is at least controlled by the switching state of the driving unit; and
a fuse connected in series within a circuit structure formed by the first power supply and the driving unit, for controlling a current path between the first power supply and the light emitting unit,
wherein, in a repair mode, a current flowing through the fuse is configured such that the fuse is blown, thereby cutting off the current path between the first power source and the light emitting cell such that the light emitting cell stops emitting light.
Optionally, when the plurality of pixel circuits enter the repair mode,
for a pixel circuit that has not failed, the control unit controls the driving unit to be turned off, a current path between the second power supply and the fuse to be turned off,
for a failed pixel circuit, the control unit controls the driving unit to be conducted, and a current path between the second power supply and the fuse is conducted.
Alternatively, the driving unit includes a first transistor and a second transistor connected in series, the light emitting unit is connected to a series node between the first transistor and the second transistor,
wherein in the repair mode, the control terminal of the first transistor receives a first control voltage provided by the control unit, the control terminal of the second transistor receives a second control voltage provided by the control unit,
at least one of the first control voltage and the second control voltage is a first level to turn off at least one of the first transistor and the second transistor for the non-malfunctioning pixel circuit, and both the first control voltage and the second control voltage are a second level to turn on the first transistor and the second transistor for the malfunctioning pixel circuit.
Optionally, the first power supply is a high level voltage, the second power supply is a low level voltage,
in the repair mode, the control unit configures the first control voltage and/or the second control voltage to control a current flowing through the first transistor and/or the second transistor such that the current flowing through the fuse is greater than/equal to a blowing current.
Optionally, the first power supply is a high-level voltage, the second power supply is a low-level voltage, and the pixel circuit further includes:
a switch unit connected in parallel to both ends of the driving unit, the switching state of which is controlled by at least a third control voltage provided by the control unit,
wherein, in the repair mode, for the non-malfunctioning pixel circuit, the control unit configures the first control voltage and/or the second control voltage to turn off the first transistor and/or the second transistor, and configures the third control voltage to turn off the switching unit,
for the failed pixel circuit, the control unit configures the third control voltage to turn on the switching unit so that the driving unit is short-circuited, and thus the current flowing through the fuse is greater than/equal to a fusing current.
Optionally, the method further includes:
a detection unit that divides the plurality of pixel circuits into the non-malfunctioning pixel circuit and the malfunctioning pixel circuit based on an optical principle; and
a processing unit converting the coordinate position of each of the malfunctioning pixel circuits into a timing signal for controlling the control unit,
wherein, in the repair mode, the control unit controls a switching state of the driving unit based on the timing signal.
Optionally, in the repair mode, the first power supply is a high-level voltage, and the second power supply is a first low-level voltage;
in the working mode, the first power supply is a high level voltage, the second power supply is a second low level voltage,
wherein the second low level voltage is greater than the first low level voltage, a voltage difference between the first low level voltage and the high level voltage is such that a current flowing through the fuse is greater than/equal to a blowing current of the fuse, a voltage difference between the second low level voltage and the high level voltage is such that a current flowing through the fuse is less than the blowing current of the fuse, and the second low level voltage is less than a bright voltage of the light emitting unit.
According to a second aspect of the present invention, there is provided a driving method of a pixel circuit including a fuse and a driving unit connected in series between a first power source and a second power source, a control unit connected to the driving unit, and a light emitting unit, the driving method comprising:
in a repair mode, a current flowing through the fuse is configured such that the fuse is blown, thereby cutting off the current path between the first power source and the driving unit such that the light emitting unit stops emitting light.
Optionally, the first power supply is a high-level voltage, the second power supply is a low-level voltage, and in the repair mode, the control unit configures a first control voltage and/or a second control voltage to control a current flowing through a first transistor and/or a second transistor in the driving unit, so that the current flowing through the fuse is greater than or equal to a fusing current; or
The first power supply is a high-level voltage, the second power supply is a low-level voltage, and in the repair mode, a third control voltage is configured to turn on the switch units connected in parallel to two ends of the driving unit, so that the driving unit is short-circuited, and thus the current flowing through the fuse is greater than or equal to a fusing current; or
In the repair mode, the first power supply is a high level voltage, and the second power supply is a first low level voltage; in an operating mode, the first power source is a high level voltage, the second power source is a second low level voltage, wherein the second low level voltage is greater than the first low level voltage, a voltage difference between the first low level voltage and the high level voltage is such that a current flowing through the fuse is greater than or equal to a blowing current of the fuse, a voltage difference between the second low level voltage and the high level voltage is such that a current flowing through the fuse is less than the blowing current of the fuse, and the second low level voltage is less than a bright voltage of the light emitting unit.
According to a third aspect of the present invention, there is provided a display panel comprising a plurality of pixel circuits as described above.
According to the pixel circuit, the driving method thereof and the display panel, the current flowing through the fuse wire is controlled, and the fuse wire is utilized to perform circuit breaking treatment on the pixel circuit with a fault (namely the pixel circuit with a bright spot defect) in the display panel, so that accurate and effective electric bright spot repair is realized, the bright spot repair efficiency is improved, and the cost is reduced.
Drawings
The above and other objects, features and advantages of the present invention will become more apparent from the following description of embodiments of the present invention with reference to the accompanying drawings, in which:
FIG. 1 shows a schematic diagram of a display panel according to an embodiment of the invention;
FIG. 2 shows a block diagram of a pixel circuit according to an embodiment of the invention;
fig. 3 shows a circuit diagram of a pixel circuit according to an embodiment of the invention;
FIG. 4 shows a block diagram of a fuse according to an embodiment of the invention;
fig. 5 illustrates level waveform diagrams of a first power supply and a second power supply according to an embodiment of the present invention;
fig. 6 shows a flowchart of a driving method of a pixel circuit according to an embodiment of the present invention.
Detailed Description
The invention will be described in more detail below with reference to the accompanying drawings. Like elements are denoted by like reference numerals throughout the various figures. For purposes of clarity, the various features in the drawings are not necessarily drawn to scale. Moreover, certain well-known elements may not be shown in the figures.
In the following description, numerous specific details of the invention, such as structure, materials, dimensions, processing techniques and techniques of the devices are described in order to provide a more thorough understanding of the invention. However, as will be understood by those skilled in the art, the present invention may be practiced without these specific details.
It should be understood that, in the embodiments of the present application, a and B are connected/coupled, which means that a and B may be connected in series or in parallel, or a and B may pass through other devices, and the embodiments of the present application do not limit this.
The following detailed description of embodiments of the present invention is provided in connection with the accompanying drawings and examples.
Fig. 1 shows a schematic diagram of a display panel according to an embodiment of the present invention. Fig. 1 illustrates a display panel according to an embodiment of the invention, taking an Active-Matrix Organic Light Emitting Diode (AMOLED) as an example. It should be understood that the present invention is not limited to the type of the display panel, for example, the display panel may also be a silicon-based OLED display panel, a micro led display panel, a miniLED display panel, an AM miniLED display panel, etc.
As shown in fig. 1, the AMOLED display panel 100 includes a plurality of pixel circuits 110 arranged in an array in a display region, and includes a gamma voltage generating circuit 10, a source driving circuit 120, a gate driving circuit 130, and a power chip 140 in a non-display region. The source driver circuit 120 generates a plurality of gray scale voltages according to the gamma voltage Vgma provided by the gamma voltage generator circuit 10, and transmits the plurality of gray scale voltages to the pixel circuits 110 via the source lines S1 to Sn; the gate driving circuit 130 supplies scan signals to the pixel circuits 110 on each row via the gate lines G1 to Gm; the power supply chips 140 are respectively connected to the respective pixel circuits 110 and supply the power supply voltage ELVDD to the respective pixel circuits 110.
Fig. 2 shows a block diagram of a pixel circuit according to an embodiment of the invention. As shown in fig. 2, the pixel circuit 110 includes a driving unit 111, a control unit 112, a light emitting unit 113, and a fuse (fuse) R1.
The driving unit 111 is connected between a first power supply VDD and a second power supply VDS; the control unit 112 is connected to the driving unit 111 for controlling the on-off state of the driving unit 111; the light emitting unit 113 is connected to a first power supply VDD via the driving unit 111, and a light emitting state of the light emitting unit 113 is controlled by at least a switching state of the driving unit 111; the fuse R1 is connected in series within a circuit structure formed by the driving unit 111 and the first power supply VDD, and serves to control a current path between the first power supply VDD and the light emitting unit 113. In this embodiment, the fuse R1 is connected between the first power source VDD and the driving unit 111, and in an alternative embodiment, when the driving unit 11 includes a plurality of circuit elements inside, the fuse R1 may also be connected in series between the plurality of elements to control the current path from the first power source VDD to the driving unit 111, thereby further controlling the current path from the first power source VDD to the light emitting unit 113.
Fuse R1 has the following characteristics: when the current flowing through the fuse is smaller than the fusing current, the fuse is in a Low Resistance State (LRS); when the current flowing through the fuse wire is larger than or equal to the fusing current, the fuse wire is fused, and the circuit connected in series with the fuse wire is broken.
Immediately after the pixel circuit 110 is shipped, the fuse R1 is in a low resistance state. The first terminal of the light emitting unit 113 is connected to a first power VDD through the driving unit 111, the second terminal is connected to a common power VCOM, and a voltage difference between the two terminals of the light emitting unit 113 is greater than a bright voltage of the light emitting unit 113, so that the light emitting unit 113 can emit light normally.
Due to the limitation of the yield of the manufacturing process, the bottom layer driving circuit has partial dead spots, and the transistors in the pixel circuits cannot be turned off, so that the display panel (see fig. 1) has bright spots when displaying black images, which often occurs during the use of the display panel. Once the bright point defect occurs on the display panel, the pixel circuit 110 with the bright point defect in the display panel can be controlled to enter a repair mode.
Specifically, in one example, in the repair mode of the pixel circuit 110, the first power supply VDD is a high-level voltage, the second power supply VDS is a first low-level voltage, and a voltage difference between the high-level voltage provided by the first power supply VDD and the first low-level voltage provided by the second power supply VDS is such that a current flowing through the fuse R1 is greater than or equal to a fusing current of the fuse R1, so that the fuse R1 is fused, thereby cutting off a current path between the first power supply VDD and the driving unit 111, and stopping the light emission of the light emitting unit 113, thereby achieving the purpose of bright point repair.
In other examples, in the repair mode of the pixel circuit 110, the first power supply VDD is a first high level voltage, the second power supply VDS is a low level voltage, and a voltage difference between the first high level voltage provided by the first power supply VDD and the low level voltage provided by the second power supply VDS is such that a current flowing through the fuse R1 is greater than/equal to a blowing current of the fuse R1; in the operation mode of the pixel circuit 110, the first power supply VDD is a second high level voltage, the second power supply VDS is a low level voltage, and a voltage difference between the second high level voltage provided by the first power supply VDD and the low level voltage provided by the second power supply VDS is such that a current flowing through the fuse R1 is smaller than a fusing current of the fuse R1, and the second high level voltage is used as a normal operation voltage of the pixel circuit 110 to prevent the fuse in the normally operating pixel circuit from being fused.
In still other examples, in the repair mode and the operation mode of the pixel circuit 110, the first power supply VDD is a high level voltage and the second power supply VDS is a low level voltage, that is, the voltage difference between the first power supply VDD and the second power supply VDS does not need to be controlled to be changed. In this example, various alternative schemes may be implemented to blow the fuse R1 for the purpose of breaking the failed pixel circuit 110.
For example, the first power supply VDD and the second power supply VDS may be short-circuited so that the current flowing through the fuse R1 is very large to blow the fuse R1. Alternatively, the first power supply VDD and the second power supply VDS may be shorted by providing a switch unit (not shown) connected in parallel to two ends of the driving unit 111, the switch unit being controlled by a third control voltage provided by the control unit 112, for example, for the failed pixel circuit 110, the third control voltage controls the switch unit to be turned on (in a low resistance state, the resistance is close to 0) to short the driving unit 111, so that a large current may flow through the fuse R1, and the large current may not flow through the driving unit 111, and may not damage the transistor and other elements in the driving unit 111.
For another example, the current flowing through the first transistor and/or the second transistor may be controlled by the first control voltage and/or the second control voltage provided by the control unit 112, so that the current flowing through the fuse is greater than or equal to the blowing current. It should be understood that the present invention is not limited thereto, and any scheme capable of blowing the fuse R1 in the pixel circuit 110 can be applied to the present invention.
In other embodiments, for a display panel with a portion of the pixel circuits 110 suffering from a bright dot defect, a plurality of pixel circuits 110 included in the display panel may be controlled to enter a repair mode. When the plurality of pixel circuits 110 enter the repair mode, for the pixel circuit 110 that has not failed, the control unit 112 controls the driving unit 111 to be turned off, the current path between the second power supply VDS and the fuse R1 is turned off, so that the current flowing through the fuse R1 is 0, and the fuse R1 is still in a low-resistance state; for the failed pixel circuit 110, the control unit 112 controls the driving unit 111 to be turned on, the current path between the second power supply VDS and the fuse R1 is turned on, the voltage across the fuse R1 reaches the threshold voltage at which the fuse is blown, and the fuse R1 is blown.
As an example, the pixel circuit 110 further includes a detection unit 114 and a processing unit 115, and the detection unit 114 divides the plurality of pixel circuits 110 in the display panel into the pixel circuits 110 that do not malfunction and the pixel circuits 110 that malfunction, for example, based on an optical principle, and transmits the coordinate positions of the respective pixel circuits 110 that malfunction to the processing unit 115. For example, after the display panel displays the black pattern, a coordinate position (X, Y, Z) where the bright point defect occurs may be located based on an optical principle, X is an abscissa, Y is an ordinate, and Z is one of (R/G/B) three. In the repair mode, the processing unit 115 converts the coordinate position of the failed pixel circuit 110 into a timing signal for controlling the control unit 112, and the control unit 112 controls the switching state of the driving unit 111 based on the timing signal representing the coordinate position of the failed pixel circuit 110, for example, the control unit 112 controls the driving unit 111 thereof to be turned on and sets the first power supply VDD to a first low-level voltage and the second power supply VDS to a high-level voltage after receiving the timing signal representing the coordinate position of the failed pixel circuit 110, so that the fuse R1 is blown.
After the repair mode of the pixel circuit 110 is ended, the fuse R1 is in a blown state even if the reverse bias voltage supplied from the first power supply VDD and the second power supply VDS is removed or restored to the forward bias voltage. Even if the pixel circuit 110 enters the normal operation mode after that, the fuse R1 can still be maintained in the blown state to avoid the bright point defect. For example, in the operation mode, the first power supply VDD is a second high level voltage, the second power supply VDS is a low level voltage, and the fuse R1 is maintained in the blown state for the failed pixel circuit 110; for the pixel circuit 110 that has not failed, the voltage difference between the second high level voltage and the low level voltage causes the current flowing through the fuse R1 to be smaller than the blowing current of the fuse R1, so that the fuse R1 maintains the low-resistance state.
Fig. 3 shows a circuit diagram of a pixel circuit according to an embodiment of the present invention. The pixel circuit of the embodiment of the present application is described in detail as an example, and it should be understood that the present invention is not limited thereto, and the technical solution of the present invention is also applicable to various forms of pixel circuits such as conventional 2T1C, 3T1C, 4T1C, and 5T 2C.
As shown in fig. 3, the pixel circuit 110 includes a driving unit 111, a control unit 112, a light emitting unit 113, a fuse R1, a detecting unit 114, and a processing unit 115, and the general structure and basic principle thereof can be seen in fig. 2, and the details of the same parts are not repeated herein. The driving unit 111, the control unit 112, the light emitting unit 113, and the fuse R1 form a basic pixel structure in the pixel circuit 110, and the detecting unit 114 and the processing unit 115 may be integrated in a peripheral circuit of a display area of the display panel or a chip as a peripheral circuit of the basic pixel structure.
In this embodiment, the driving unit 111 includes a first transistor M1 and a second transistor M2 connected in series, and the light emitting unit 113 is an organic light emitting diode OLED. The first transistor M1 functions as a driving transistor, the second transistor M2 functions as a reset transistor, an anode of the organic light emitting diode OLED is connected to a series node between the first transistor M1 and the second transistor M2, and a cathode of the organic light emitting diode OLED is connected to a common power supply VCOM. In an alternative embodiment, a fuse R1 may be connected between the first transistor M1 and the second transistor M2 to control a current path between the first power source VDD and the driving unit 112, i.e., to control a current path between the first power source VDD and the organic light emitting diode OLED.
The control terminal of the first transistor M1 receives the first control voltage SW1 provided by the control unit 112, and the control terminal of the second transistor M2 receives the second control voltage SW2 provided by the control unit 112. When the first control voltage SW1 is at a first level, the first transistor M1 is turned off, and when the first control voltage SW1 is at a second level, the first transistor M1 is turned on, and the turn-on characteristic of the second transistor M2 is similar to that of the first transistor M1, which is not described herein again.
In this embodiment, the first transistor M1 and the second transistor M2 are both P-type transistors, and the first level is set to high level and the second level is set to low level. In an alternative embodiment, the first transistor M1 and the second transistor M2 may be N-type transistors, and the first level is set to a low level and the second level is set to a high level.
In the repair mode, for the pixel circuit 110 that has not failed, at least one of the first control voltage SW1 and the second control voltage SW2 supplied from the control unit 112 is at the first level to turn off the first transistor M1 and the second transistor M2; for the failed pixel circuit 110, the first control voltage SW1 and the second control voltage SW2 provided by the control unit 112 are both at the second level to turn on the first transistor M1 and the second transistor M2.
In the repair mode, after the display panel displays the black pattern, the detection unit 114 may be located to a coordinate position (X, Y, Z) where the bright point defect occurs based on an optical principle, X is an abscissa, Y is an ordinate, and Z is one of (R/G/B), and the processing unit 115 generates a timing signal for controlling the control unit 112 according to the coordinate position where the bright point defect occurs. In the repair mode, the control unit 112 controls the switching state of the driving unit 111 based on a timing signal that can characterize the coordinate position of the failed pixel circuit 110. For example, the processing unit 115 controls the level of the first control voltage SW1 supplied from the control unit 112 using X and Z in the coordinate position and controls the level of the first control voltage SW2 supplied from the control unit 112 using Y in the coordinate position, and thus, after the control unit 112 receives a timing signal representing the coordinate position of the failed pixel circuit 110, the first control voltage SW1 and the second control voltage SW2 of the second level may be supplied to control the driving unit 111 thereof to be turned on and set the first power supply VDD to a low level voltage and the second power supply VDS to a high level voltage, so that the fuse R1 is blown.
As an example, the control unit 112 includes, for example, a switching tube and a storage capacitor (not shown). In the working mode, the on and off of the switching tube are controlled by a scanning signal; the storage capacitor is used for receiving the gray scale voltage through the switch tube and storing the gray scale voltage; the first transistor M1 is used to provide a driving voltage or a driving current to the organic light emitting diode OLED according to the power voltage and the stored gray scale voltage during the off phase of the switching tube.
Fig. 4 shows a structural diagram of a fuse according to an embodiment of the present invention. It should be understood that any other structure and material of fuse may be used instead of the fuse shown in fig. 4 and applied to the pixel circuits shown in fig. 2 and 3.
As shown in fig. 4, the fuse 200 includes a first structural layer 201, a second structural layer 202, and a third structural layer 203 between the first structural layer 201 and the second structural layer 202. The fuse 200 serves as the fuse R1 mentioned in fig. 2 and 3.
In one embodiment, the first structural layer 201 is a dielectric layer, the second structural layer 202 is a protective layer, and the third structural layer is a metal layer 203, which is a fuse body structural layer.
Fig. 5 illustrates level waveform diagrams of the first power supply and the second power supply according to an embodiment of the present invention, the abscissa indicates time, and the ordinate indicates relative magnitude of voltage. It should be understood that the voltage magnitude, ratio, holding time, etc. of the first power supply and the second power supply shown in fig. 5 are exemplary descriptions, and the first power supply and the second power supply shown in fig. 5 do not limit the specific parameters of the first power supply and the second power supply provided by the embodiment of the present invention
As shown in fig. 5, the first power supply VDD is maintained at the high level voltage V3, the second power supply VDS is selectively switched between the first low level voltage V1 and the second low level voltage V2 based on different modes, the first low level voltage V1 is less than the second low level voltage V2, and a voltage difference between the high level voltage V3 and the first low level voltage V1 makes a current flowing through the fuse greater than/equal to a blowing current of the fuse, and a voltage difference between the high level voltage V3 and the second low level voltage V2 makes a current flowing through the fuse less than the blowing current of the fuse.
In the detection mode T1 of the pixel circuit, the first power supply VDD is set to the high level voltage V3, the second power supply VDS is set to the second low level voltage V2, so that the fuse is in the low resistance state, and at this time, the light emitting unit is connected to the first power supply via the driving unit and receives the high level voltage V3, which pixel circuits have the bright point defect can be detected, and the coordinate position of the pixel circuit having the bright point defect is recorded.
In the repair mode T2 of the pixel circuit, the first power supply VDD is set to the high level voltage V3, the second power supply VDS is set to the first low level voltage V1, the driving unit is turned on for the pixel circuit where the bright point defect occurs, and both ends of the fuse respectively receive the high level voltage V3 and the first low level voltage V1, so that the fuse is blown; for the pixel circuit without the bright point defect, the driving unit is turned off, one end of the fuse is floated, and the other end of the fuse receives the first low-level voltage V1, so that the fuse is maintained in a low-resistance state.
In the operation mode T3 of the pixel circuit, the first power supply VDD is set to the high level voltage V3, the second power supply VDS is set to the second low level voltage V2, the fuse is still maintained in the blown state for the pixel circuit where the bright point defect occurs, the current path from the first power supply VDD to the light emitting cell is cut off, and thus the light emitting cell does not emit light; for a pixel circuit where no light point defect occurs, such that the fuse is maintained in a low resistance state, the light emitting unit may receive a driving voltage or current via the driving circuit, and thus may emit light normally.
The pixel circuit provided by the invention has the following advantages:
1) the fuse wire has a simple structure and is easy to realize, and only some structural layers are required to be added on the wafer on the basis of the structure of the traditional pixel circuit, so that accurate bright spot repair of the display panel can be realized on the premise of not increasing pixel circuit devices;
2) compared with the traditional laser repairing method, the high cost of the laser equipment required in the laser repairing method can be saved;
4) the efficiency of repairing the display panel can be improved, and at most, only one frame (about 16 ms) can be used for realizing all repairing works;
5) the repair of a single display panel can be realized, and a plurality of display panels can be repaired together, wherein the cost of repairing the plurality of display panels is only a control circuit, which is relatively insignificant compared with that of repairing a single display panel;
6) each pixel circuit can be accurately repaired, the repair yield of the display panel can be improved, and theoretically, the repair yield of the display panel can reach 100%;
7) the Active Matrix (AM) display panel is suitable for various Active Matrix (AM) panels such as OLED large-size panels (flexible plates and rigid plates), silicon-based OLED and micro panels, and has a wide application range.
Fig. 6 shows a flowchart of a driving method of a pixel circuit according to an embodiment of the present invention.
An embodiment of the present invention further provides a driving method for a pixel circuit, where the pixel circuit includes a fuse and a driving unit connected in series between a first power supply and a second power supply, and a control unit and a light emitting unit connected to the driving unit, and specific structures of the pixel circuit may be referred to in fig. 2 to 4, which are not described herein again. The driving method of the pixel circuit includes steps S1-S3.
Step S1: in the detection mode, the first power supply, the second power supply, and the control unit are configured to detect a malfunctioning pixel circuit. At this time, the light emitting unit is connected to the first power supply through the driving unit, and the control unit controls all pixel circuits in the display panel to display black, while the failed pixel circuit emits light, so that the step can detect which pixel circuits have the bright point defect, and record the coordinate position of the pixel circuit having the bright point defect.
Step S2: in the repair mode, a current flowing through the fuse is configured such that the fuse is blown, thereby cutting off a current path from the light emitting cell to the first power source such that the light emitting cell stops emitting light. For example, the first power source is configured to a high level voltage, and the second power source is configured to a first low level voltage, so that the fuse is blown.
In some embodiments, when the plurality of pixel circuits enter the repair mode, the control unit is used to control the driving unit to be turned off and the current path between the first power supply and the fuse to be turned off for the pixel circuit which does not fail, and the control unit is used to control the driving unit to be turned on and the current path between the first power supply and the fuse to be turned on for the pixel circuit which fails.
Step S3: in the operation mode, the first power supply, the second power supply, and the control unit are configured so that the pixel circuit operates normally.
In one example, the first power supply in the detection mode, the repair mode and the operation mode is a high-level voltage, the second power supply is a low-level voltage, and in the repair mode, the control unit configures the first control voltage and/or the second control voltage to control a current flowing through the first transistor and/or the second transistor such that the current flowing through the fuse is greater than or equal to the blowing current.
In another example, the first power source in the detection mode, the repair mode and the operation mode is a high level voltage, the second power source is a low level voltage, and in the repair mode, the third control voltage is configured to turn on the switch units connected in parallel to the two ends of the driving unit, so that the driving unit is short-circuited, and thus the current flowing through the fuse is greater than or equal to the fusing current.
In yet another example, in the repair mode, the first power supply is a high level voltage, and the second power supply is a first low level voltage; in the working mode, the first power supply is a high level voltage, the second power supply is a second low level voltage, wherein the second low level voltage is greater than the first low level voltage, a voltage difference between the first low level voltage and the high level voltage enables a current flowing through the fuse to be greater than or equal to a blowing current of the fuse, a voltage difference between the second low level voltage and the high level voltage enables the current flowing through the fuse to be less than the blowing current of the fuse, and the second low level voltage is less than a bright voltage of the light emitting unit.
It should be understood that steps S1 and S3 are optional steps, and in some embodiments, step S2 may be performed separately, for example, in the case that the coordinate position of the failed pixel circuit in the display panel is known, step S2 may be performed directly on the failed pixel circuit to repair the pixel circuit from a bright point to a dark point.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
In accordance with embodiments of the present invention, as set forth above, these embodiments are not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. The invention is limited only by the claims and their full scope and equivalents.
Claims (10)
1. A pixel circuit, comprising:
a driving unit connected between a first power supply and a second power supply;
the control unit is connected to the driving unit and used for controlling the on-off state of the driving unit;
the light-emitting unit is connected to the first power supply through the driving unit, and the light-emitting state of the light-emitting unit is at least controlled by the switching state of the driving unit; and
a fuse connected in series within a circuit structure formed by the first power supply and the driving unit, for controlling a current path between the first power supply and the light emitting unit,
wherein, in the repair mode, a voltage difference between the first power supply and the second power supply is configured such that a current flowing through the fuse is greater than/equal to a blowing current of the fuse, so that the fuse is blown, thereby cutting the current path between the first power supply and the light emitting unit such that the light emitting unit stops emitting light,
in an operating mode, a voltage difference between the first power supply and the second power supply is configured such that a current flowing through the fuse is smaller than a blowing current of the fuse.
2. The pixel circuit of claim 1, wherein when a plurality of pixel circuits enter the repair mode,
for a pixel circuit that has not failed, the control unit controls the driving unit to be turned off, a current path between the second power supply and the fuse to be turned off,
for a failed pixel circuit, the control unit controls the driving unit to be conducted, and a current path between the second power supply and the fuse is conducted.
3. The pixel circuit according to claim 2, wherein the driving unit includes a first transistor and a second transistor connected in series, the light emitting unit is connected to a series node between the first transistor and the second transistor,
wherein in the repair mode, the control terminal of the first transistor receives a first control voltage provided by the control unit, the control terminal of the second transistor receives a second control voltage provided by the control unit,
at least one of the first control voltage and the second control voltage is a first level to turn off at least one of the first transistor and the second transistor for the non-malfunctioning pixel circuit, and both the first control voltage and the second control voltage are a second level to turn on the first transistor and the second transistor for the malfunctioning pixel circuit.
4. The pixel circuit according to claim 3, wherein the first power source is a high-level voltage, the second power source is a low-level voltage,
in the repair mode, the control unit configures the first control voltage and/or the second control voltage to control a current flowing through the first transistor and/or the second transistor such that the current flowing through the fuse is greater than/equal to a blowing current.
5. The pixel circuit according to claim 3, wherein the first power supply is a high-level voltage, and the second power supply is a low-level voltage, the pixel circuit further comprising:
a switch unit connected in parallel to both ends of the driving unit, the switching state of which is controlled by at least a third control voltage provided by the control unit,
wherein, in the repair mode, for the non-malfunctioning pixel circuit, the control unit configures the first control voltage and/or the second control voltage to turn off the first transistor and/or the second transistor, and configures the third control voltage to turn off the switching unit,
for the failed pixel circuit, the control unit configures the third control voltage to turn on the switching unit so that the driving unit is short-circuited, and thus the current flowing through the fuse is greater than/equal to a fusing current.
6. The pixel circuit according to claim 2, further comprising:
a detection unit that divides the plurality of pixel circuits into the non-malfunctioning pixel circuit and the malfunctioning pixel circuit based on an optical principle; and
a processing unit converting the coordinate position of each of the malfunctioning pixel circuits into a timing signal for controlling the control unit,
wherein, in the repair mode, the control unit controls a switching state of the driving unit based on the timing signal.
7. The pixel circuit according to claim 1,
in a repair mode, the first power supply is a high level voltage, and the second power supply is a first low level voltage;
in the working mode, the first power supply is a high level voltage, the second power supply is a second low level voltage,
wherein the second low level voltage is greater than the first low level voltage, a voltage difference between the first low level voltage and the high level voltage is such that a current flowing through the fuse is greater than/equal to a blowing current of the fuse, a voltage difference between the second low level voltage and the high level voltage is such that a current flowing through the fuse is less than the blowing current of the fuse, and the second low level voltage is less than a bright voltage of the light emitting unit.
8. A driving method of a pixel circuit including a fuse and a driving unit connected in series between a first power source and a second power source, a control unit connected to the driving unit, and a light emitting unit, the driving method comprising:
in a repair mode, a voltage difference between the first power supply and the second power supply is configured such that a current flowing through the fuse is greater than/equal to a blowing current of the fuse, so that the fuse is blown, thereby cutting off a current path between the first power supply and the driving unit such that the light emitting unit stops emitting light,
in an operating mode, a voltage difference between the first power supply and the second power supply is configured such that a current flowing through the fuse is smaller than a blowing current of the fuse.
9. The driving method according to claim 8,
the first power supply is a high-level voltage, the second power supply is a low-level voltage, and in the repair mode, the control unit configures a first control voltage and/or a second control voltage to control a current flowing through a first transistor and/or a second transistor in the driving unit, so that the current flowing through the fuse is greater than or equal to a fusing current; or
The first power supply is a high-level voltage, the second power supply is a low-level voltage, and in the repair mode, a third control voltage is configured to turn on the switch units connected in parallel to two ends of the driving unit, so that the driving unit is short-circuited, and thus the current flowing through the fuse is greater than or equal to a fusing current; or
In the repair mode, the first power supply is a high level voltage, and the second power supply is a first low level voltage; in an operating mode, the first power source is a high level voltage, the second power source is a second low level voltage, wherein the second low level voltage is greater than the first low level voltage, a voltage difference between the first low level voltage and the high level voltage is such that a current flowing through the fuse is greater than or equal to a blowing current of the fuse, a voltage difference between the second low level voltage and the high level voltage is such that a current flowing through the fuse is less than the blowing current of the fuse, and the second low level voltage is less than a bright voltage of the light emitting unit.
10. A display panel comprising a plurality of pixel circuits according to any one of claims 1 to 7.
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| KR101178561B1 (en) * | 2010-08-30 | 2012-09-03 | 에스케이하이닉스 주식회사 | Semiconductor memory device and operating method thereof |
| CN106782318B (en) * | 2016-12-21 | 2019-06-14 | 京东方科技集团股份有限公司 | A kind of pixel circuit and its driving method, display device |
| KR102657536B1 (en) * | 2018-10-24 | 2024-04-12 | 엘지디스플레이 주식회사 | Display panel and method of deactivating light emitting diode in display panel |
| CN109712663A (en) * | 2018-12-29 | 2019-05-03 | 上海华力集成电路制造有限公司 | Fuse programming unit, fuse circuit and its programming process |
| CN111179848A (en) * | 2020-01-02 | 2020-05-19 | 深圳市华星光电半导体显示技术有限公司 | Pixel circuit, display panel and display device thereof |
| CN112509521A (en) * | 2020-12-11 | 2021-03-16 | 深圳市智联汇网络系统企业(有限合伙) | Driving circuit and method for repairing normally-on OLED (organic light emitting diode) pixels and display device |
| CN113140684B (en) * | 2021-04-16 | 2022-05-31 | 南京国兆光电科技有限公司 | Micro OLED display screen and bright spot defect laser repairing method thereof |
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