Driving circuit of light-emitting element, self-compensation method of driving circuit, pixel circuit and array

Abstract

The invention discloses a driving circuit of a light-emitting element, a self-compensation method of the driving circuit, a pixel circuit and an array, and the driving circuit comprises a voltage storage unit which is suitable for storing a data voltage signal received by a first switch unit; the driving unit is suitable for receiving the data voltage signal in the voltage storage unit and converting the data voltage signal into a driving current for driving a light-emitting element; and a second switching unit suitable for testing the drift amount of the threshold voltage test value of the driving unit relative to the target value. According to the driving circuit provided by the embodiment of the invention, after the second switch unit is turned on to test the current value flowing through the second switch unit, the current value is suitable for judging the drift distance of the threshold voltage test value of the driving unit relative to the target value, so that the threshold voltage of the driving unit can be compensated based on the drift distance; therefore, the complexity of the design of the driving circuit is reduced, and the brightness display of the light-emitting elements is unified.

Description

Technical Field

[0001] Embodiments of the present invention relate to the field of integrated circuit manufacturing, and in particular, to a driving circuit for a light-emitting element, a self-compensation method thereof, a pixel circuit, and an array. Background Art

[0002] Most of the transistors in existing pixel driving circuits are made of low-temperature polysilicon thin-film transistors or oxide thin-film transistors. Compared with general amorphous silicon thin-film transistors, low-temperature polysilicon thin-film transistors and oxide thin-film transistors have higher mobilities and more stable characteristics, and are more suitable for application in active matrix organic light-emitting diode (OLED) displays.

[0003] However, due to the limitations of the crystallization process, low-temperature polysilicon thin-film transistors fabricated on a large-area glass substrate often have non-uniformity problems in electrical parameters such as threshold voltage and mobility. This non-uniformity will be converted into differences in driving current and brightness of organic light-emitting diode devices, and will be perceived by the human eye, that is, the color non-uniformity phenomenon. Although the oxide thin-film transistor has better process uniformity, similar to the amorphous silicon thin-film transistor, under long-term pressurization and high temperature, its threshold voltage will drift, resulting in different display images. Due to different threshold drift amounts of the thin-film transistors in each part of the panel, it will cause differences in brightness of the light-emitting devices and display non-uniformity. Summary of the Invention

[0004] The problem solved by the embodiments of the present invention is to provide a driving circuit for a light-emitting element, a self-compensation method thereof, a pixel circuit, and an array, to improve the performance of the driving circuit so as to make the brightness display of the light-emitting element uniform.

[0005] To solve the above problems, an embodiment of the present invention provides a driving circuit for a light-emitting element, including: a first switch unit adapted to receive a data voltage signal; a voltage storage unit coupled to the first switch unit and adapted to store the data voltage signal received by the first switch unit, the voltage storage unit and the first switch unit being coupled at a first node; a driving unit coupled to the first node, adapted to receive the data voltage signal stored in the voltage storage unit, and convert the data voltage signal into a driving current for driving the light-emitting element; and a second switch unit coupled to the driving unit and adapted to test the drift amount of the threshold voltage test value of the driving unit relative to a target value.

[0006] An embodiment of the present invention further provides a pixel circuit, including: the driving circuit according to the embodiment of the present invention; and a light-emitting element coupled between the output node of the driving unit and the ground voltage signal.

[0007] An embodiment of the present invention further provides a pixel array, including a plurality of pixel circuits according to the embodiments of the present invention.

[0008] Correspondingly, an embodiment of the present invention further provides a self-compensation method for a driving circuit of a light-emitting element. By a scanning voltage signal, the first switching unit is turned on, so that the data voltage signal is stored in the voltage storage unit through the first switching unit; after the data voltage signal is stored in the voltage storage unit through the first switching unit, the first switching unit is turned off by the scanning voltage signal; after the first switching unit is turned off, the voltage storage unit supplies power to the driving unit through the stored data voltage signal; the second switching unit is turned on, and the current value flowing through the second switching unit is tested, and the current value is suitable for judging the drift amount of the threshold voltage test value of the driving unit relative to the target value; the second switching unit is turned off, and the threshold voltage of the driving unit is compensated based on the drift amount.

[0009] Compared with the prior art, the technical solution of the embodiment of the present invention has the following advantages:

[0010] An embodiment of the present invention provides a driving circuit of a light-emitting element, a first switching unit, adapted to receive a data voltage signal, a voltage storage unit, coupled to the first switching unit, adapted to store the data voltage signal received by the first switching unit, the voltage storage unit and the first switching unit are coupled at a first node, a driving unit, coupled to the first node, the driving unit is adapted to receive the data voltage signal stored in the voltage storage unit, and convert the data voltage signal into a driving current for driving the light-emitting element, a second switching unit, coupled to the driving unit, adapted to test the drift amount of the threshold voltage test value of the driving unit relative to the target value. In the embodiment of the present invention, when the second switching unit is turned on, the driving unit and the second switching unit are in series, and the current of the driving unit is equal to the current of the second switching unit. Therefore, subsequently, only by testing the current value flowing through the second switching unit, the drift amount of the test value of the driving unit relative to the target value can be judged, and there is no need to add additional circuit components to judge the drift amount of the test value of the driving unit relative to the target value. That is, the drift of the threshold voltage can be known by electrical testing, which is convenient for compensating the driving unit and shortens the development cycle; correspondingly, when the driving circuit is applied to a light-emitting element, the brightness displayed by the light-emitting element can be made uniform.

[0011] In an alternative embodiment, the driving unit includes a floating-gate transistor, which is adapted to receive the data voltage signal stored in the voltage storage unit and convert the data voltage signal into a driving current for driving the light-emitting element. By using a floating-gate transistor, by adjusting the corresponding voltage applied to its control gate, the threshold voltage of the floating-gate transistor can be adjusted, thereby reducing the complexity of the driving circuit, reducing the area of the pixel region, correspondingly reducing the chip area, and further improving the integration of the chip.

[0012] An embodiment of the present invention provides a pixel circuit, including the driving circuit described in the embodiment of the present invention; and a light-emitting element coupled between the output node of the driving unit and the ground voltage signal. Since the circuit designed according to the embodiment of the present invention can obtain the drift of the threshold voltage through electrical testing, it is convenient to make the threshold voltages of the driving units in the pixel circuit consistent through a self-compensation method, so that the brightness of the light-emitting elements is unified, and further improves the performance of the pixel circuit.

[0013] An embodiment of the present invention further provides a pixel array, including a plurality of pixel circuits described in the embodiment of the present invention. Since the threshold voltages of the driving units in the pixel circuit provided by the embodiment of the present invention are consistent, the brightness of the light-emitting elements in the pixel array is unified, and thus the brightness of the pixel array formed by the pixel circuits provided by the embodiment of the present invention is uniform, improving the performance of the pixel array.

[0014] An embodiment of the present invention provides a self-compensation method for a driving circuit designed according to the present invention. By scanning a voltage signal to turn on the first switch unit, the data voltage signal is stored in the voltage storage unit through the first switch unit; after the data voltage signal is stored in the voltage storage unit through the first switch unit, the first switch unit is turned off by the scanning voltage signal; after the first switch unit is turned off, the voltage storage unit supplies power to the driving unit through the stored data voltage signal; the second switch unit is turned on, and the current value flowing through the second switch unit is measured. The current value is suitable for judging the drift amount of the threshold voltage test value of the driving unit relative to the target value; the second switch unit is turned off, and the threshold voltage of the driving unit is compensated based on the drift amount. In the embodiment of the present invention, the self-compensation method is used to compensate the threshold voltage of the driving circuit of the light-emitting element described in the foregoing embodiment, and the drift amount of the threshold voltage of the driving unit can be obtained through electrical testing, and the threshold voltage of the driving unit is compensated based on the drift amount, so as to facilitate compensation for the driving unit, reduce the complexity and precision of self-compensation, and shorten the development cycle; correspondingly, when the driving circuit is applied to a light-emitting element, the brightness of the light-emitting element can be unified. Description of the Drawings

[0015] Figure 1 It is a schematic diagram of the circuit structure of a pixel circuit;

[0016] Figure 2 It is a schematic diagram of the frame structure of the driving circuit of a light-emitting element in an embodiment of the present invention;

[0017] Figure 3 It is a schematic diagram of the circuit structure of the driving circuit of a light-emitting element in an embodiment of the present invention;

[0018] Figure 4 It is a schematic diagram of the circuit structure of a pixel circuit in an embodiment of the present invention;

[0019] Figure 5 It is a schematic diagram of the structure of a first switch unit in an embodiment of the present invention;

[0020] Figure 6 It is a schematic diagram of the structure of a driving unit in an embodiment of the present invention;

[0021] Figure 7 It is a schematic diagram of the structure of a second switch unit in an embodiment of the present invention;

[0022] Figures 8 to 9 It is a schematic diagram of the principle of compensating the threshold voltage by a driving unit in an embodiment of the present invention;

[0023] Figure 10 It is a flowchart of the self-compensation method of a driving circuit in an embodiment of the present invention. Detailed implementation manners

[0024] As can be seen from the background art, in the existing pixel driving circuit, there are problems that the threshold drifts of the thin-film transistors in each part are different, resulting in brightness differences and uneven display of the light-emitting devices.

[0025] Figure 1 It is a schematic diagram of the circuit structure of a pixel circuit.

[0026] Refer to Figure 1 , the pixel circuit includes: a first switch unit M1, coupled between a scan voltage signal V scan1 and a data voltage signal V data1 , adapted to receive the data voltage signal V scan1 under the control of the scan voltage signal V data1 ; a voltage storage unit C1, coupled between the output node of the first switch unit M1 and a power supply voltage signal V DD1 , adapted to store the data voltage signal V data1; a driving unit M2, coupled between the output node of the first switching unit M1 and a power supply voltage signal V DD1 therebetween, the driving unit M2 being adapted to receive the data voltage signal V stored in the voltage storage unit C1 data1 , and converting the data voltage signal V data1 into a driving current for driving the light-emitting element L1; a light-emitting element L1, coupled between the output node of the driving unit M2 and a ground voltage signal V ss1 therebetween.

[0027] A pixel array is composed of a plurality of pixel circuits. It has been found through research that in practical applications, due to various reasons (such as process fluctuations, etc.), the threshold voltages of the driving units M2 in the pixel circuits are not the same, resulting in differences in the brightness values displayed by the light-emitting elements L1 in the pixel array.

[0028] In the prior art, usually after connecting the light-emitting elements L1 to form a pixel array and turning on all the light-emitting elements L1, compensation is performed according to the actual brightness of the light-emitting elements L1 to reduce the influence of the threshold voltage drift of the driving unit M2 on the brightness of the light-emitting elements L1 and improve the brightness uniformity of the light-emitting elements L1.

[0029] However, performing compensation after turning on the light-emitting elements L1 usually takes a long time, resulting in an increase in time cost.

[0030] To solve the above technical problem, an embodiment of the present invention provides a driving circuit for a light-emitting element, including: a first switching unit, adapted to receive a data voltage signal; a voltage storage unit, coupled to the first switching unit and adapted to store the data voltage signal received by the first switching unit, the voltage storage unit and the first switching unit being coupled at a first node; a driving unit, coupled to the first node and adapted to receive the data voltage signal stored in the voltage storage unit and convert the data voltage signal into a driving current for driving the light-emitting element; a second switching unit, coupled to the driving unit and adapted to test the drift amount of the threshold voltage test value of the driving unit relative to a target value.

[0031] In the scheme disclosed in the embodiment of the present invention, when the second switch unit is turned on, the driving unit is connected in series with the second switch unit, and the current of the driving unit is equal to the current of the second switch unit. Therefore, the drift of the driving unit test value relative to the target value can be determined by testing the current value flowing through the second switch unit, without adding additional circuit components to determine the drift of the driving unit test value relative to the target value. That is, the drift of the threshold voltage can be known by electrical testing, which is convenient for compensation for the driving unit and shortens the development cycle; accordingly, when the driving circuit is applied to the light-emitting element, the brightness displayed by the light-emitting element can be made uniform.

[0032] In order to make the above-mentioned purposes, features and advantages of the embodiments of the present invention more obvious and understandable, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0033] Figure 2 is a schematic diagram of the framework structure of a driving circuit of a light emitting element in an embodiment of the present invention, Figure 3 It is a schematic diagram of the circuit structure of a driving circuit of a light emitting element in one embodiment of the present invention.

[0034] Combined with reference Figure 2 and reference Figure 3 The driving circuit of the light emitting element L2 includes: a first switch unit 100, adapted to receive a data voltage signal V data ; A voltage storage unit 200, coupled to the first switch unit 100, adapted to store the data voltage signal V received by the first switch unit 100 data , the voltage storage unit 200 and the first switch unit 100 are coupled to a first node A; the driving unit 300 is coupled to the first node A and is adapted to receive the data voltage signal V stored in the voltage storage unit 200 data , and the data voltage signal V data The second switch unit 400 is coupled to the driving unit 300 and is suitable for testing the drift of the threshold voltage test value of the driving unit 300 relative to the target value.

[0035] Specifically, the first switch unit 100 is coupled to the scan voltage signal V scan With the data voltage signal V data between the scanning voltage signal V scan The data voltage signal V is received under control data ; The voltage storage unit 200 is coupled to the output node out1 of the first switch unit 100 and the power supply voltage signal V DD The driving unit 300 is coupled to the first node A and the power supply voltage signal VDD between; a second switch unit 400, coupled between the output node out2 of the driving unit 300 and the ground voltage signal V ss and is adapted to test the drift amount of the threshold voltage test value of the driving unit 300 relative to the target value in the on state.

[0036] It should be noted that when the driving unit 300 is performing driving work, it is coupled between the first node A and the power supply voltage signal V DD . In other words, when the driving unit 300 is performing driving work, the driving unit 300 is used to be coupled to the power supply voltage signal V DD coupled.

[0037] It should also be noted that for the convenience of understanding the working mode of the driving circuit, Figure 3 in the dashed line is used to represent the light-emitting element L2, and the connection relationship between the light-emitting element L2 and the driving circuit is schematically shown.

[0038] In this embodiment, the driving circuit is used to test the drift amount of the threshold voltage test value of the driving unit 300 relative to the target value, and in subsequent work, the threshold voltage of the driving unit 300 is compensated to improve the stability of the threshold voltage of the driving unit 300, so that the brightness displayed by the light-emitting element L2 is unified.

[0039] In this embodiment, the first switch unit 100 is used to control the voltage storage unit 200 to receive the data voltage signal V data .

[0040] Specifically, the first switch unit 100 includes a first input node, a second input node and an output node out1. Among them, the first input node of the first switch unit 100 is used to receive the scan voltage signal V scan , the second input node of the first switch unit 100 is used to receive the data voltage signal V data , the output node out1 of the first switch unit 100 is used to be coupled to the voltage storage unit 200, and is used to output the data voltage signal V data .

[0041] By the scan voltage signal V scan to control the on or off of the first switch unit 100, thereby controlling the first switch unit 100 to receive the data voltage signal V data , and output the received data voltage signal V data to the voltage storage unit 200.

[0042] It should be noted that in this embodiment, the scan voltage signal V scan and the data voltage signal Vdata All are provided by an external driving chip.

[0043] In combination with reference Figure 2 and reference Figure 5 , Figure 5 FIG. Figure 5 is a schematic structural diagram of a first switching unit in an embodiment of the present invention. In this embodiment, the first switching unit 100 includes a first transistor T1. The gate 16 of the first transistor T1 is coupled to the scan voltage signal V scan and serves as or is coupled to the first input node of the first switching unit 100. The drain 13 of the first transistor T1 is coupled to the data voltage signal V data and serves as or is coupled to the second input node of the first switching unit 100. The source 12 of the first transistor T1 is coupled to the voltage storage unit 200 and is used to serve as or be coupled to the output node out1 of the first switching unit 100.

[0044] Specifically, referring to Figure 5 , the first transistor T1 is a control gate transistor. The gate 16 of the first transistor T1 is composed of a gate oxide layer 11 and a control gate 10 located on the gate oxide layer 11. That is to say, the first transistor is a common MOS transistor.

[0045] Correspondingly, the control gate 10 of the first transistor is coupled to the scan voltage signal V scan and is coupled.

[0046] In this embodiment, the first transistor T1 includes an NMOS transistor or a PMOS transistor. As an example, the first transistor T1 is an NMOS transistor.

[0047] Specifically, the type of the first transistor T1 is mainly related to the material of the light-emitting element. In one embodiment, when the type of the first transistor T1 is a PMOS transistor, the production cost can be reduced, and at the same time, the resolution of the pixel circuit can be improved.

[0048] In this embodiment, the voltage storage unit 200 is used to store the data voltage signal V data received by the first switching unit 100.

[0049] In this embodiment, the first end of the voltage storage unit 200 is coupled to the output node out1 of the first switching unit 100 for receiving the data voltage signal V data , and the second end of the voltage storage unit 200 is coupled to the power supply voltage signal V DDCoupled to receive the power supply voltage signal V DD .

[0050] In this embodiment, the voltage storage unit 200 includes a capacitor C2. One end of the capacitor C2 is coupled to the power supply voltage signal V DD coupled, and the other end of the capacitor C2 is coupled to the output node out1 of the first switch unit 100.

[0051] Specifically, the capacitor C2 has the advantage of a large storage capacity. The capacitor C2 has a large storage capacity, can store and read a large amount of data, thereby improving the storage function of the driving circuit, and further improving the performance of the driving circuit.

[0052] In this embodiment, the capacitor C2 includes a MIM capacitor.

[0053] Specifically, the MIM capacitor has the advantage of a high storage density. The MIM capacitor has a high storage density, thereby improving the integration degree of the driving circuit.

[0054] In this embodiment, the driving unit 300 is used to receive the data voltage signal V stored in the voltage storage unit 200 data , and convert the data voltage signal V data into a driving current for driving the light emitting element L2.

[0055] Specifically, the driving unit 300 includes a first input node, a second input node, and an output node out2. Among them, the first input node of the driving unit 300 is used to receive the data voltage signal V stored in the voltage storage unit 200 data , the second input node of the driving unit 300 is used to receive the power supply voltage signal V DD , and the output node out2 of the driving unit 300 is used to output a driving current signal.

[0056] In this embodiment, the driving unit 300 is coupled between the first node A and the second end of the voltage storage unit 200.

[0057] It should be noted that the output node out1 of the first switch unit 100 is not only coupled to the first input node of the driving unit 300, but also coupled to the first end of the voltage storage unit 200, that is, the first input node of the driving unit 300 is coupled to the first end of the voltage storage unit 200, then the driving unit 300 is coupled between the two ends of the voltage storage unit 200. Therefore, when the first switch unit 100 is closed, the data voltage signal V stored in the voltage storage unit 200 dataProvide voltage for the driving unit 300 to enable it to continue operating.

[0058] With reference to Figure 2 、 Figure 3 and Figure 6 , Figure 6 FIG. is a schematic structural diagram of a driving unit in an embodiment of the present invention. In this embodiment, the driving unit 300 includes a floating-gate transistor T2, and the floating-gate transistor T2 is adapted to receive the data voltage signal V stored in the voltage storage unit 200 data ,and convert the data voltage signal V data into a driving current for driving the light-emitting element L2.

[0059] In this embodiment, as shown in reference Figure 6 , the gate 26 of the floating-gate transistor T2 is composed of a tunneling oxide layer 25, a floating gate 24, an oxide layer 21, and a control gate 20 stacked in sequence from bottom to top.

[0060] It should be noted that when the floating-gate transistor T2 performs self-compensation, the same level is applied to the source 22, drain 23, and substrate 27 of the floating-gate transistor T2, and another level is applied to the control gate 20 of the floating-gate transistor T2; when the floating-gate transistor T2 performs driving operation, the drain 23 of the floating-gate transistor T2 is coupled to the power supply voltage signal V DD coupled.

[0061] In this embodiment, the floating-gate transistor T2 includes an NMOS transistor or a PMOS transistor.

[0062] Specifically, the type of the floating-gate transistor T2 is mainly related to the material of the light-emitting element. In one embodiment, when the type of the floating-gate transistor T2 is a PMOS transistor, the production cost can be reduced, and at the same time, the resolution of the pixel circuit can be improved.

[0063] It should be noted that the amount of charge stored in the floating gate 24 affects the magnitude of the threshold voltage of the floating-gate transistor T2, and the amount of charge stored in the floating gate 24 is controlled by the control gate 20. Therefore, when a corresponding voltage is applied to the control gate 20 of the floating-gate transistor T2, the attraction or repulsion of charges to or from the floating gate 24 can be controlled, thereby achieving the control of the amount of charge stored in the floating gate 24, and further adjusting the threshold voltage of the floating-gate transistor T2.

[0064] One way to adjust the threshold voltage is to use a 4T2C compensation circuit or a 6T1C compensation circuit to compensate for the threshold voltage of the driving unit. However, the 4T2C compensation circuit or the 6T1C compensation circuit compensates for the threshold voltage of the driving unit by adding multiple sets of circuit components in the traditional pixel circuit, which increases the complexity of the pixel circuit, thereby increasing the area of the pixel region, correspondingly increasing the area of the chip, and thus reducing the integration degree of the chip. Compared with the prior art, the driving unit 300 in the embodiment of the present invention uses a floating-gate transistor T2, which can enable the driving circuit to achieve self-compensation of the threshold voltage. By adjusting the voltage applied to its control gate 20, the threshold voltage of the floating-gate transistor T2 can be adjusted, thereby reducing the complexity of the driving circuit, reducing the area of the pixel region, correspondingly reducing the chip area, and further improving the integration degree of the chip.

[0065] Moreover, the floating-gate transistor T2 has a non-volatile characteristic, that is, when powered off or after power-off, the floating-gate transistor T2 still maintains the state of storing charges. In the subsequent operation of the driving circuit, due to the non-volatile characteristic of the floating-gate transistor T2, the floating-gate transistor T2 can achieve a long-term threshold voltage compensation effect.

[0066] In this embodiment, the control gate 20 of the floating-gate transistor T2 is coupled to the output node out1 (i.e., the first node A) of the first switch unit 100 for receiving the data voltage signal V data , and serves as the first input node of the driving unit 300 or is coupled to the first input node of the driving unit 300. The source 22 of the floating-gate transistor T2 is coupled to the second switch unit 400 for outputting a driving current, and serves as the output node of the driving unit 300 or is coupled to the output node of the driving unit 300. The drain 23 of the floating-gate transistor T2 is coupled to the power supply voltage signal V DD for receiving the power supply voltage signal V DD , and serves as the second input node out2 of the voltage storage unit 200 or is coupled to the second input node out2 of the voltage storage unit 200.

[0067] In this embodiment, the second switch unit 400 is used to test the drift amount of the threshold voltage test value of the driving unit 300 relative to the target value in the on state.

[0068] When the second switch unit 400 is turned on, the driving unit 300 is connected in series with the second switch unit 400, and the current of the driving unit 300 is equal to the current of the second switch unit 400. Therefore, in the following, only by measuring the current value flowing through the second switch unit 400, the drift amount of the measured value of the driving unit 300 relative to the target value can be determined, without the need to add additional circuit components to determine the drift amount of the measured value of the driving unit 300 relative to the target value. That is, the drift situation of the threshold voltage can be known by electrical testing, which is convenient for compensating the driving unit 300 in time and shortening the development cycle. Correspondingly, when the driving circuit is applied to the light-emitting element L2, the brightness displayed by the light-emitting element L2 can be made uniform.

[0069] Specifically, the second switch unit 400 includes a control node, a first input node, and a second input node. Among them, the control node of the second switch unit 400 is used to receive the test voltage signal V test , so as to control the second switch unit 400 to be turned on or off. The first input node of the second switch unit 400 is used to receive the driving current signal, and the second input node of the second switch unit 400 is used to receive the ground voltage signal V ss .

[0070] With reference to Figure 2 、 Figure 3 and Figure 7 , Figure 7 is a schematic structural diagram of the second switch unit in an embodiment of the present invention. The second switch unit 400 includes a second transistor T3. The gate 36 of the second transistor T3 is coupled to the test voltage signal V test for receiving the test voltage signal V test , and serves as the control node of the second switch unit 400 or is coupled to the control node of the second switch unit 400. The drain 33 of the second switch transistor is coupled to the output node out2 of the driving unit 300 (that is, coupled to the source 22 of the floating-gate transistor T2) for receiving the driving current signal, and serves as the first input node of the second switch unit 400 or is coupled to the first input node of the second switch unit 400. The source 32 of the second transistor T3 is coupled to the ground voltage signal V ss for receiving the ground voltage signal V ss , and serves as the second input node of the second switch unit 400 or is coupled to the second input node of the second switch unit 400.

[0071] In this embodiment, as Figure 7As shown, the second switch unit 400 is a control-gate transistor. The gate 16 of the second transistor T3 is composed of a gate oxide layer 31 and a control gate 30 located on the gate oxide layer 31. That is to say, the second transistor T3 is an ordinary MOS transistor.

[0072] Correspondingly, the control gate 30 of the second transistor T3 is coupled to the test voltage signal V test coupled.

[0073] In this embodiment, the second transistor T3 includes an NMOS transistor or a PMOS transistor.

[0074] As an example, the second transistor T3 includes an NMOS transistor.

[0075] In this embodiment, both the first switch unit 100 and the second switch unit 400 are control-gate transistors.

[0076] Specifically, both the first switch unit 100 and the second switch unit 400 are control-gate transistors, that is, there is no floating-gate structure in the transistor structures of the first switch unit 100 and the second switch unit 400 (as shown in Figure 5 and Figure 7 shown). Therefore, when a voltage is applied to the driving unit 300 later to compensate its threshold voltage, the first switch unit 100 and the second switch unit 400 will not be affected.

[0077] Correspondingly, referring to Figure 4 , Figure 4 is a schematic circuit diagram of a pixel circuit in an embodiment of the present invention. The embodiment of the present invention also provides a pixel circuit, including: the driving circuit provided in the embodiment of the present invention; a light-emitting element L2, coupled between the output node of the driving unit 300 and the ground voltage signal V ss therebetween.

[0078] Since the circuit designed by the embodiment of the present invention can know the drift of the threshold voltage by electrical testing, it is convenient to make the threshold voltages of the driving units in the pixel circuit consistent through self-compensation, so that the brightness of the light-emitting elements is unified, and thus the performance of the pixel circuit is improved.

[0079] It should be noted that when the driving unit 300 of the driving circuit in the embodiment of the present invention adopts the floating gate transistor T2, by adjusting the corresponding voltage applied to its control gate 20, the threshold voltage of the floating gate transistor T2 can be adjusted. Then, the driving circuit can make the threshold voltages of the driving units 300 in the pixel circuit consistent through a self-compensation method, thereby reducing the complexity of the pixel circuit, decreasing the area of the pixel region, correspondingly reducing the chip area, and further improving the integration degree of the chip.

[0080] In this embodiment, in the driving circuit, the second switch unit 400 is in an off state, so that the current of the driving unit 300 completely flows through the light-emitting element L2, and the presence of the second switch unit 400 does not affect the light emission of the light-emitting element L2. That is to say, when the second switch unit 400 includes the second transistor T3, when the second switch unit 400 does not test the drift amount of the threshold voltage test value of the driving unit 300 relative to the target value, the second transistor T3 is in a closed state.

[0081] In this embodiment, the light-emitting element L2 includes an organic light-emitting diode.

[0082] Specifically, in the pixel circuit, each organic light-emitting diode corresponds to a pixel. Since the organic light-emitting diode has the characteristic of self-luminescence and does not require a backlight source, when the pixel circuit displays black, the pixel is completely turned off, so that a very high contrast and a pure black display effect can be achieved. At the same time, the pixel circuit composed of organic light-emitting diodes only consumes energy when it needs to display brightness. Since each pixel in the pixel circuit is self-luminous, when the pixel circuit displays black or dark colors, the pixels in the pixel circuit are completely turned off, thereby reducing the power consumption of the pixel circuit.

[0083] Correspondingly, the present invention also provides a pixel array, including a plurality of pixel circuits according to the embodiments of the present invention.

[0084] Specifically, since the threshold voltages of the driving units 300 in the pixel circuit provided by the embodiment of the present invention are consistent, the brightnesses displayed by the light-emitting elements L2 in the pixel array are unified, and further the brightness displayed by the pixel array composed of the pixel circuits provided by the embodiment of the present invention is uniform, improving the performance of the pixel array.

[0085] Correspondingly, the present invention also provides a self-compensation method for the driving circuit designed according to the embodiments of the present invention, and the self-compensation method is used to compensate the threshold voltage of the driving unit 300.

[0086] Figures 8 to 9 It is a schematic diagram of the principle of compensating the threshold voltage of the driving unit in an embodiment of the present invention. Figure 10It is a flowchart of the self - compensation method of the driving circuit in an embodiment of the present invention. Please refer to the following Figure 10 and in combination with Figures 2 to 9 to describe the self - compensation method of the embodiment of the present invention in detail.

[0087] Execute step S1. By scanning the voltage signal V scan turn on the first switch unit 100 so that the data voltage signal V data is stored in the voltage storage unit 200 through the first switch unit 100.

[0088] Make the data voltage signal V data be stored in the voltage storage unit 200 through the first switch unit 100, so that subsequently the voltage storage unit 200 supplies power to the driving unit 300 through the stored data voltage signal V data for the driving unit 300.

[0089] In this embodiment, the first switch unit 100 is an NMOS transistor; the step of turning on the NMOS transistor through the scanning voltage signal V scan includes: making the scanning voltage signal V connected to the NMOS transistor scan be the second level, where the second level is higher than the first level.

[0090] When the first switch unit 100 is an NMOS transistor, when the connected scanning voltage signal V scan is the second level, that is, applying the second level to the gate 16 of the first switch unit 100. At this time, a conductive channel is formed between the source 12 and the drain 13 of the first switch unit 100, so that the first switch unit 100 is turned on.

[0091] In some other embodiments, the first switch unit 100 is a PMOS transistor; then the step of turning on the PMOS transistor through the scanning voltage signal V scan includes: making the scanning voltage signal V connected to the PMOS transistor scan be the first level, where the first level is lower than the second level.

[0092] When the first switch unit 100 is a PMOS transistor, when the connected scanning voltage signal V scan is the first level, that is, applying the first level to the gate 16 of the first switch unit 100. At this time, a conductive channel is formed between the source 12 and the drain 13 of the first switch unit 100, so that the first switch unit 100 is turned on.

[0093] Specifically, the second level includes a positive voltage signal; the first level includes a negative voltage signal.

[0094] Execute step S2. After the data voltage signal V data is stored in the voltage storage unit 200 through the first switching unit 100, the first switching unit 100 is turned off by the scanning voltage signal V scan In this embodiment, the first switching unit 100 is an NMOS transistor; the step of turning off the NMOS transistor by the scanning voltage signal V

[0095] includes: making the scanning voltage signal V scan connected to the NMOS transistor be a first level, where the first level is lower than the second level. scan When the connected scanning voltage signal V

[0096] is the first level, that is, applying the first level to the gate 16 of the first switching unit 100. At this time, no conductive channel can be formed between the source 12 and the drain 13 of the first switching unit 100, so the first switching unit 100 is cut off. scan

[0097] In some other embodiments, the first switching unit 100 is a PMOS transistor; the step of turning off the PMOS transistor by the scanning voltage signal includes: making the scanning voltage signal V scan connected to the PMOS transistor be a second level, where the second level is higher than the first level.

[0098] When the connected scanning voltage signal V scan is the second level, that is, applying the second level to the gate 16 of the first switching unit 100. At this time, no conductive channel can be formed between the source 12 and the drain 13 of the first switching unit 100, so the first switching unit 100 is cut off.

[0099] Specifically, the second level includes a positive voltage signal; the first level includes a negative voltage signal.

[0100] Execute step S3. After the first switching unit 100 is turned off, the voltage storage unit 200 supplies power to the driving unit 300 through the stored data voltage signal V data Make the voltage storage unit 200 supply power to the driving unit 300 through the stored data voltage signal V

[0101] so that after the second switching unit 400 is turned on subsequently, the current value flowing through the second switching unit 400 can be tested. data

[0102] ​​Execute step S4, turn on the second switch unit 400, and test the current value flowing through the second switch unit 400. The current value is suitable for judging the drift amount of the threshold voltage test value of the driving unit 300 relative to the target value.

[0103] Specifically, the driving unit 300 receives the data voltage signal V stored in the voltage storage unit 200 data , and converts the data voltage signal V data into a driving current. At this time, the second switch unit 400 is turned on, and the driving current flows through the second switch unit 400. When the second switch unit 400 is turned on, the driving unit 300 is connected in series with the second switch unit 400, and the driving current is equal to the current of the second switch unit 400. Therefore, subsequently, by testing the current value flowing through the second switch unit 400, the drift amount of the test value of the driving unit 300 relative to the target value can be judged.

[0104] It should be noted that the self-compensation method is used to perform threshold voltage compensation on the driving circuit of the light-emitting element L2 described in the foregoing embodiment, and the drift amount of the threshold voltage of the driving unit 300 can be obtained by electrical testing, and the threshold voltage of the driving unit 300 is compensated based on the drift amount, so as to facilitate compensation for the driving unit 300, reduce the complexity and precision of the compensation, and shorten the development cycle; correspondingly, when the driving circuit is applied to the light-emitting element L2, the brightness displayed by the light-emitting element L2 can be made uniform.

[0105] In this embodiment, the driving unit 300 includes a floating-gate transistor T2, and the floating-gate transistor T2 is suitable for receiving the data voltage signal V stored in the voltage storage unit 200 data , and converts the data voltage signal V data into a driving current for driving the light-emitting element L2.

[0106] Correspondingly, the step of compensating the threshold voltage of the driving unit 300 based on the drift amount includes: applying a corresponding voltage to the control gate 20 of the floating-gate transistor T2 based on the drift amount of the threshold voltage to adjust the threshold voltage of the floating-gate transistor T2.

[0107] For the description of the floating-gate transistor T2, reference can be made to the relevant description in the foregoing embodiment, and details are not described herein again.

[0108] In this embodiment, the floating-gate transistor T2 includes an N-type transistor or a P-type transistor.

[0109] It should be noted that when the floating gate transistor T2 performs self-compensation, the same level is applied to the source 22, drain 23, and substrate 27 of the floating gate transistor T2, and another level is applied to the control gate 20 of the floating gate transistor T2; when the floating gate transistor T2 performs driving work, the drain 23 of the floating gate transistor T2 is coupled to the power supply voltage signal V DD coupled.

[0110] Specifically, when the floating gate transistor T2 is an N-type transistor, the method for adjusting the threshold voltage of the N-type transistor includes: when the measured value of the threshold voltage of the driving unit 300 is greater than the target value, applying a first level to the control gate 20 of the N-type transistor, and applying a second level to the source 22, drain 23, and substrate 27 of the NMOS transistor to reduce the threshold voltage of the N-type transistor; when the measured value of the threshold voltage of the driving unit is less than the target value, applying a second level to the control gate 20 of the N-type transistor, and applying a first level to the source 22, drain 23, and substrate 27 of the N-type transistor to increase the threshold voltage of the N-type transistor; wherein, the first level is lower than the second level.

[0111] Referring Figure 8 , when the floating gate transistor T2 is an N-type transistor, applying a first level (where the first level includes a negative voltage) to the control gate 20 of the floating gate transistor T2 will repel electrons, correspondingly reducing the number of electrons in the floating gate 24, thereby reducing the number of positive charges attracted from the substrate. It is easier to form a conductive channel between the source 22 and drain 23 of the N-type floating gate transistor T2, and thus the N-type floating gate transistor T2 is more likely to conduct. Therefore, the threshold voltage of the floating gate transistor T2 will be reduced.

[0112] Referring Figure 9 , when the floating gate transistor T2 is an N-type transistor, applying a second level (where the second level includes a positive voltage) to the control gate 20 of the floating gate transistor T2 will attract electrons, and the electrons will tunnel through the tunneling oxide layer and reach the floating gate 24. When the test voltage is removed, there is no discharge path in the floating gate 24 of the floating gate transistor T2, and the electrons will remain in the floating gate 24. Since the floating gate 24 contains a large number of electrons (negative charges), it will attract positive charges in the substrate, and when the N-type floating gate transistor T2 conducts, the conductive channel needs to be negative charges. Therefore, it is difficult to form a conductive channel between the source 22 and drain 23 of the N-type floating gate transistor T2. Therefore, the threshold voltage of the floating gate transistor T2 will be increased.

[0113] In some other embodiments, when the floating - gate transistor T2 is a P - type transistor, the method for adjusting the threshold voltage of the P - type transistor includes: when the measured threshold voltage of the driving unit is greater than the target value, applying a second level to the control gate 20 of the P - type transistor, and applying a first level to the source 22, drain 23, and substrate 27 of the P - type transistor to reduce the threshold voltage of the P - type transistor; when the measured threshold voltage of the driving unit is less than the target value, applying a second level to the control gate 20 of the P - type transistor, and applying a first level to the source 22, drain 23, and substrate 27 of the P - type transistor to increase the threshold voltage of the P - type transistor; wherein, the first level is lower than the second level.

[0114] When the floating - gate transistor T2 is a P - type transistor, it is contrary to the principle when the floating - gate transistor T2 is an N - type transistor. For the specific analysis, the principle of the N - type transistor can be referred to and will not be elaborated here.

[0115] In this embodiment, the second switching unit 400 includes a second transistor T3. The gate 36 of the second transistor T3 is coupled to the test voltage signal V test The drain 33 of the second transistor T3 is coupled to the output node of the driving unit 300, and the source 32 of the second transistor T3 is coupled to the ground voltage signal V ss

[0116] Wherein, when the second transistor T3 is an NMOS transistor, the step of turning on the NMOS transistor and measuring the current value flowing through the NMOS transistor includes: making the test voltage signal applied to the gate 36 a positive voltage signal and measuring the source - drain current value flowing through the NMOS transistor.

[0117] When the second transistor T3 is an NMOS transistor, when the test voltage signal V test applied to the gate 36 is a positive voltage signal, at this time, a conductive channel is formed between the source 32 and the drain 33 of the second transistor T3, and thus the second transistor T3 is turned on.

[0118] When the second transistor T3 is a PMOS transistor, the step of turning on the PMOS transistor and measuring the current value flowing through the PMOS transistor includes: making the test voltage signal applied to the gate 36 a negative voltage signal and measuring the source - drain current value flowing through the PMOS transistor.

[0119] When the second transistor T3 is a PMOS transistor, when the test voltage signal V test applied to the gate 36 is a negative voltage signal, at this time, a conductive channel is formed between the source 32 and the drain 33 of the second transistor T3, and thus the second transistor T3 is turned on.​

[0120] It should also be noted that when the second transistor T3 is turned on, the second transistor T3 is in series with the driving unit 300 at this time, that is, the current flowing through the driving unit 300 is equal to the source-drain current of the second transistor T3; since the drain 33 of the second transistor T3 is coupled to the output node out2 of the driving unit 300, that is, the driving current of the driving unit 300 will flow through the second transistor T3, therefore, by subsequently testing the current value flowing through the second switching unit 400, the drift amount of the test value of the driving unit 300 relative to the target value can be judged.

[0121] Execute step S5, turn off the second switching unit 400, and compensate the threshold voltage of the driving unit 300 based on the drift amount.

[0122] In this embodiment, the method of compensating the threshold voltage of the driving unit 300 based on the drift amount includes: based on the drift amount, obtaining the compensation amount of the threshold voltage of the driving unit 300, so that after the light-emitting element L2 is connected, the threshold voltages of the driving units 300 tend to be consistent.

[0123] Specifically, based on the drift amount, obtain the load voltage value required for the control gate 20 of the floating-gate transistor T2, and the load voltage value is used to adjust the threshold voltage of the driving unit 300 to make the threshold voltages of the driving units 300 tend to be consistent.

[0124] It should be noted that in this embodiment, in the self-compensation method, the light-emitting element L2 is not connected to the driving circuit.

[0125] Specifically, the self-compensation method does not need to be performed when the light-emitting element L2 is lit, but judges the drift amount of the threshold voltage test value of the driving unit 300 relative to the target value by testing the current value flowing through the second switching unit 400, and then compensates the threshold voltage of the driving unit 300 based on the drift amount, thereby reducing the time-consuming for compensating the threshold voltage of the driving unit 300, and further shortening the development cycle of the driving circuit of the light-emitting element L2.

[0126] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be subject to the scope defined by the claims.

Claims

1. A driving circuit for a light-emitting element, characterized in that, Comprising: A first switch unit, adapted to receive a data voltage signal; A voltage storage unit, coupled to the first switch unit, adapted to store the data voltage signal received by the first switch unit, and the voltage storage unit is coupled to the first switch unit at a first node; A driving unit, coupled to the first node, adapted to receive the data voltage signal stored in the voltage storage unit, and convert the data voltage signal into a driving current for driving the light-emitting element; A second switch unit, coupled to the driving unit, adapted to test the drift amount of the threshold voltage test value of the driving unit relative to a target value.

2. The drive circuit of the light-emitting element according to claim 1, characterized in that The driving unit is coupled between the first node and a power supply voltage signal.

3. The driving circuit of the light-emitting element according to claim 1, characterized in that, The driving unit includes a floating-gate transistor, and the floating-gate transistor is adapted to receive the data voltage signal stored in the voltage storage unit, and convert the data voltage signal into a driving current for driving the light-emitting element.

4. The driving circuit of the light-emitting element according to claim 3, characterized in that, The control gate of the floating-gate transistor is coupled to the first node, the source of the floating-gate transistor is coupled to the second switch unit, and the drain of the floating-gate transistor is coupled to the power supply voltage signal.

5. The driving circuit of the light-emitting element according to claim 1, characterized in that, The first switch unit is coupled between a scan voltage signal and the data voltage signal, and is adapted to receive the data voltage signal under the control of the scan voltage signal.

6. The driving circuit of the light-emitting element according to claim 5, characterized in that, The first switch unit includes a first transistor, the gate of the first transistor is coupled to the scan voltage signal, the drain of the first transistor is coupled to the data voltage signal, the source of the first transistor is coupled to the voltage storage unit, and is used as the output node of the first switch unit or is coupled to the output node of the first switch unit.

7. The driving circuit of the light-emitting element according to claim 1, characterized in that, The voltage storage unit is coupled between the output node of the first switch unit and the power supply voltage signal.

8. The driving circuit of the light-emitting element according to claim 7, characterized in that, The first end of the voltage storage unit is coupled to the output node of the first switch unit, and the second end of the voltage storage unit is coupled to the power supply voltage signal; The driving unit is coupled between the first node and the second end of the voltage storage unit.

9. The driving circuit of the light-emitting element according to claim 1, wherein The second switch unit is coupled between the output node of the driving unit and a ground voltage signal, and is adapted to test the drift amount of the threshold voltage test value of the driving unit relative to a target value in an on state.

10. The drive circuit of the light-emitting element according to claim 9, characterized in that, The second switch unit includes a second transistor, the gate of the second transistor is coupled to a test voltage signal, the drain of the second transistor is coupled to the output node of the driving unit, and the source of the second transistor is coupled to the ground voltage signal.

11. The driving circuit of the light-emitting element according to any one of claims 1 to 10, characterized in that, Both the first switch unit and the second switch unit are control-gate transistors.

12. The drive circuit of the light-emitting element according to any one of claims 1 to 10, characterized in that, The voltage storage unit includes a capacitor, one end of the capacitor is coupled to the power supply voltage signal, and the other end of the capacitor is coupled to the output node of the first switch unit.

13. The drive circuit of the light-emitting element according to claim 12, characterized in that, The capacitor includes a MIM capacitor.

14. A pixel circuit, characterized in that, Comprising: The driving circuit according to any one of claims 1 to 13; A light-emitting element, coupled between the output node of the driving unit and the ground voltage signal.

15. A pixel array, characterized in that, Including a plurality of pixel circuits according to claim 14.

16. A self-compensation method using the driving circuit according to any one of claims 1 to 13, characterized in that, Comprising: The first switching unit is turned on by a scanning voltage signal, so that the data voltage signal is stored in the voltage storage unit through the first switching unit; After the data voltage signal is stored in the voltage storage unit through the first switching unit, the first switching unit is turned off by the scanning voltage signal; After the first switching unit is turned off, the voltage storage unit supplies power to the driving unit through the stored data voltage signal; The second switching unit is turned on, and the current value flowing through the second switching unit is tested. The current value is suitable for judging the drift amount of the threshold voltage test value of the driving unit relative to the target value; The second switching unit is turned off, and the threshold voltage of the driving unit is compensated based on the drift amount.

17. The self-compensation method according to claim 16, characterized in that, The driving unit includes a floating gate transistor, which is suitable for receiving the data voltage signal stored in the voltage storage unit and converting the data voltage signal into a driving current for driving the light emitting element; The step of compensating the threshold voltage of the driving unit based on the drift amount includes: applying a corresponding voltage to the control gate of the floating gate transistor based on the drift amount of the threshold voltage to adjust the threshold voltage of the floating gate transistor.

18. The self-compensation method according to claim 17, wherein The floating gate transistor is an N-type transistor; The method of adjusting the threshold voltage of the N-type transistor includes: when the threshold voltage test value of the driving unit is greater than the target value, applying a first level to the control gate of the N-type transistor, and applying a second level to the source, drain and substrate of the N-type transistor to reduce the threshold voltage of the N-type transistor; when the threshold voltage test value of the driving unit is less than the target value, applying a second level to the control gate of the N-type transistor, and applying a first level to the source, drain and substrate of the N-type transistor to increase the threshold voltage of the N-type transistor; wherein, the first level is lower than the second level; Or, The floating gate transistor is a P-type transistor; The method of adjusting the threshold voltage of the P-type transistor includes: when the threshold voltage test value of the driving unit is greater than the target value, applying a second level to the control gate of the P-type transistor, and applying a first level to the source, drain and substrate of the P-type transistor to reduce the threshold voltage of the P-type transistor; when the threshold voltage test value of the driving unit is less than the target value, applying a second level to the control gate of the P-type transistor, and applying a first level to the source, drain and substrate of the P-type transistor to increase the threshold voltage of the P-type transistor; wherein, the first level is lower than the second level.

19. The self-compensation method according to claim 16, wherein The first switching unit is an NMOS transistor; The step of turning on the NMOS transistor by the scanning voltage signal includes: making the scanning voltage signal accessed by the NMOS transistor be the second level; the step of turning off the NMOS transistor by the scanning voltage signal includes: making the scanning voltage signal accessed by the NMOS transistor be the first level, wherein the first level is lower than the second level; Or, The first switching unit is a PMOS transistor; The step of turning on the PMOS transistor by the scan voltage signal includes: making the scan voltage signal connected to the PMOS transistor be a first level; the step of turning off the PMOS transistor by the scan voltage signal includes: making the scan voltage signal connected to the PMOS transistor be a second level, where the first level is lower than the second level.

20. The self-compensation method according to claim 16, wherein The second switching unit includes a second transistor, the gate of the second transistor is coupled to the test voltage signal, the drain of the second transistor is coupled to the output node of the driving unit, and the source of the second transistor is coupled to the ground voltage signal; In the case where the second transistor is an NMOS transistor, the step of turning on the NMOS transistor and testing the current value flowing through the NMOS transistor includes: making the test voltage signal connected to the gate be a positive voltage signal and testing the source-drain current value flowing through the NMOS transistor; Alternatively, in the case where the second transistor is a PMOS transistor, the step of turning on the PMOS transistor and testing the current value flowing through the PMOS transistor includes: making the test voltage signal connected to the gate be a negative voltage signal and testing the source-drain current value flowing through the PMOS transistor.

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