Threshold voltage detection method, detection device and display device

Abstract

The threshold voltage detection method, detection device and display device provided in the present application achieve, through a new detection process and control timing, maintaining the gate voltage of the driving transistor stable during the detection process, and then iteratively allowing the gate-source voltage of the driving transistor to be reduced to equal to the threshold voltage of the driving transistor after multiple voltage reduction iterations, thereby detecting the actual threshold voltage of the driving transistor; since the process of reducing the gate-source voltage from a state greater than the threshold voltage to a state equal to the threshold voltage is continuously iteratively updated, the detection time can be greatly shortened, thereby improving the efficiency of detecting the actual threshold voltage of the driving transistor and improving the user experience.

Description

Technical Field

[0001] The present application relates to the field of display technology, and in particular to a threshold voltage detection method, a detection device and a display device. Background Art

[0002] Organic Light Emitting Diode (OLED) display devices have been widely used in various electronic devices because of their advantages such as self-luminescence, light weight, low power consumption, high contrast, high color gamut, and flexible display. In the driving mode of an active matrix organic light emitting diode display device, a pixel driving circuit is provided with a driving transistor for driving the organic light emitting diode to emit light. Since the driving transistor operates in the saturation region, the current flowing through the driving transistor is affected by the threshold voltage and mobility of the driving transistor itself. Therefore, in order to ensure the uniformity of the display brightness of the organic light emitting diode display device, it is necessary to detect the difference in threshold voltage and mobility between different sub-pixels, and then compensate based on the detection.

[0003] In the conventional threshold voltage detection method, an initial Vgs (gate-source voltage) is provided to the driving transistor, and the gate voltage of the driving transistor is kept unchanged by using the source follower method, so that the source voltage of the driving transistor is raised to Vgs=V th (threshold voltage of the driving transistor) state, the current flowing through the driving transistor approaches zero. The source voltage of the driving transistor in this state is detected, and the threshold voltage of the driving transistor can be calculated. The obtained threshold voltage is then superimposed on the data voltage during display to compensate for the threshold voltage difference and solve the display brightness unevenness caused by the threshold voltage difference.

[0004] However, since the gate-source voltage decreases with the detection time and the parasitic capacitance of the detection circuit is much larger than the storage capacitance of a single sub-pixel, the source voltage of the driving transistor rises more and more slowly, and it takes a long time to detect the threshold voltage of the driving transistor in the pixel. This will greatly affect the factory's production capacity and the investment in detection equipment. On the other hand, the threshold voltage can only be detected under a black screen. Therefore, the standby time before the user turns on the display device or after turning off the display device will be longer, and the user experience will also be greatly affected. Summary of the invention

[0005] The present application provides a threshold voltage detection method, which can effectively shorten the threshold voltage detection time of a driving transistor, thereby improving the threshold voltage detection efficiency of the driving transistor.

[0006] In a first aspect, the present application provides a threshold voltage detection method, which comprises:

[0007] Step S1, providing a pixel, the pixel comprising a driving transistor, a first transistor, a second transistor, a capacitor and a light-emitting element; the gate of the driving transistor is electrically connected to the first node, one of the source and the drain of the driving transistor is electrically connected to the first power supply, and the other of the source and the drain of the driving transistor is electrically connected to the second node; the gate of the first transistor is electrically connected to the scan line, one of the source and the drain of the first transistor is electrically connected to the data line, and the other of the source and the drain of the first transistor is electrically connected to the first node; the gate of the second transistor is electrically connected to the control line, one of the source and the drain of the second transistor is electrically connected to the second node, and the other of the source and the drain of the second transistor is electrically connected to the detection line; the first end of the capacitor is electrically connected to the first node, and the second end of the capacitor is electrically connected to the second node;

[0008] Step S2, initializing the voltage of the first node to obtain a first initial voltage, and initializing the voltage of the second node to obtain a second initial voltage, so as to turn on the driving transistor;

[0009] Step S3, controlling the first transistor and the second transistor to be turned on, and controlling the detection line to be in a floating state, so that the voltage of the first node is maintained at the first initial voltage, and the voltage of the second node is raised, and after a preset time period, the voltage of the second node is detected to obtain a detection voltage;

[0010] Step S4, obtaining a reference threshold voltage according to the detection voltage and the first initial voltage;

[0011] Step S5, comparing the detection voltage with the second initial voltage, and if the detection voltage is equal to the second initial voltage, setting the reference threshold voltage as the actual threshold voltage of the driving transistor.

[0012] In the threshold voltage detection method provided in the present application, the threshold voltage detection method also includes: if the detection voltage is not equal to the second initial voltage, a third initial voltage is obtained according to the reference threshold voltage and the second initial voltage, and the step S2 is returned, and the third initial voltage is used to initialize the voltage of the first node in the step S2.

[0013] In the threshold voltage detection method provided in the present application, the step S4 specifically includes: obtaining the reference threshold voltage according to the difference between the first initial voltage and the detection voltage; wherein V 参考 (n) = Vg(n) - Vs(n), where V 参考Vg(n) represents the reference threshold voltage obtained in the n-th detection, Vg(n) represents the first initial voltage in the n-th detection, and Vs(n) represents the detection voltage obtained in the n-th detection.

[0014] In the threshold voltage detection method provided in the present application, the step of obtaining the third initial voltage according to the reference threshold voltage and the second initial voltage specifically includes: obtaining the third initial voltage according to the sum of the reference threshold voltage and the second initial voltage; wherein Vg(n+1)=Vpre+V 参考 (n), Vg(n+1) represents the third initial voltage obtained by the nth detection, Vpre represents the second initial voltage in each detection, and n is an integer greater than 1.

[0015] In the threshold voltage detection method provided in the present application, during the first detection, the step S2 specifically includes: the scan line provides a scan signal to turn on the first transistor, and the first data line provides a first preset voltage to the first node; the control line provides a control signal to turn on the second transistor, and the second data line provides a second preset voltage to the second node.

[0016] In the threshold voltage detection method provided in the present application, the first preset voltage is greater than the second preset voltage, and the difference between the first preset voltage and the second preset voltage is not less than the actual threshold voltage.

[0017] In the threshold voltage detection method provided in the present application, the threshold voltage detection method further includes: after the step S5, controlling the first transistor to be turned on to reset the voltage of the first node; controlling the second transistor to be turned on to reset the voltage of the second node.

[0018] In the threshold voltage detection method provided in the present application, the detection time period for executing the steps S2 to S5 is located in the vertical blank area.

[0019] In a second aspect, the present application further provides a threshold voltage device, comprising:

[0020] A pixel, the pixel comprising a driving transistor, a first transistor, a second transistor, a capacitor and a light-emitting element; the gate of the driving transistor is electrically connected to the first node, one of the source and the drain of the driving transistor is electrically connected to the first power supply, and the other of the source and the drain of the driving transistor is electrically connected to the second node; the gate of the first transistor is electrically connected to the scan line, one of the source and the drain of the first transistor is electrically connected to the data line, and the other of the source and the drain of the first transistor is electrically connected to the first node; the gate of the second transistor is electrically connected to the control line, one of the source and the drain of the second transistor is electrically connected to the second node, and the other of the source and the drain of the second transistor is electrically connected to the detection line; the first end of the capacitor is electrically connected to the first node, and the second end of the capacitor is electrically connected to the second node;

[0021] an initialization module, the initialization module being used to initialize the voltage of the first node to obtain a first initial voltage, and to initialize the voltage of the second node to obtain a second initial voltage, so as to turn on the driving transistor;

[0022] a detection module, the detection module being used to control the voltage of the first node to be maintained at the first initial voltage, so that the voltage of the second node is raised based on the first power supply, and after a preset time period, detecting the voltage of the second node to obtain a detection voltage;

[0023] a calculation module, the calculation module being used to obtain a reference threshold voltage according to the detection voltage and the first initial voltage;

[0024] A comparison module is used for comparing the detection voltage with the second initial voltage.

[0025] A storage module is used to store the reference threshold voltage. If the detection voltage is equal to the second initial voltage, the reference threshold voltage is stored as the actual threshold voltage of the driving transistor.

[0026] In the threshold voltage detection device provided in the present application, the threshold voltage detection device further includes:

[0027] A return initialization module is used for enabling the initialization module to continue initializing the voltages of the first node and the second node if the detection voltage is not equal to the second initial voltage, so as to turn on the driving transistor.

[0028] In the threshold voltage detection device provided in the present application, the threshold voltage detection device further includes:

[0029] A reset module, wherein the reset module is used to reset the voltage of the first node and reset the voltage of the second node after step S5.

[0030] In a third aspect, the present application further provides a display device, which includes the threshold voltage detection device described above.

[0031] The threshold voltage detection method provided in the present application controls the conduction of the first transistor and the second transistor in each detection process through a new detection process and control timing, so that the gate voltage of the driving transistor is maintained stable, and then through an iterative method, the gate-source voltage of the driving transistor is reduced to be equal to the threshold voltage of the driving transistor after multiple voltage reduction iterations, thereby detecting the actual threshold voltage of the driving transistor; because the process of reducing the gate-source voltage from a state greater than the threshold voltage to a state equal to the threshold voltage is continuously iterated and updated, the detection time is further significantly shortened, thereby improving the efficiency of detecting the actual threshold voltage of the driving transistor and improving the user experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic diagram of a flow chart of a threshold voltage detection method provided in an embodiment of the present application;

[0033] Figure 2 A schematic diagram of an equivalent circuit of a pixel provided in an embodiment of the present application;

[0034] Figure 3 for Figure 2 A driving timing diagram of an equivalent circuit of a pixel shown;

[0035] Figure 4 for Figure 2 Another driving timing diagram of an equivalent circuit of a pixel shown;

[0036] Figure 5 Based on Figure 1 The flowchart shown is a driving timing diagram for the first detection;

[0037] Figure 6 Based on Figure 1 The flowchart shown is a schematic diagram of the driving timing of the second detection;

[0038] Figure 7 Based on Figure 1 The flowchart shown is a driving timing diagram for the nth detection;

[0039] Figure 8 This is a structural diagram of a threshold voltage detection device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0041] In addition, the terms "first", "second", etc. in the specification and claims of this application are used to distinguish different objects rather than to describe a specific order. The terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. Since the source and drain of the transistor used in this application are symmetrical, their source and drain are interchangeable. According to the form in the accompanying drawings, the middle end of the transistor is defined as the gate, the signal input end is the source, and the output end is the drain.

[0042] See also Figure 1 , Figure 1 The first flow chart of the threshold voltage detection method provided in the embodiment of the present application is shown in FIG. Figure 1 As shown, the threshold voltage detection method provided by the embodiment of the present application includes the following steps:

[0043] Step S1, providing a pixel, the pixel comprising a driving transistor, a first transistor, a second transistor, a capacitor and a light-emitting element; the gate of the driving transistor is electrically connected to the first node, one of the source and the drain of the driving transistor is electrically connected to the first power supply, and the other of the source and the drain of the driving transistor is electrically connected to the second node; the gate of the first transistor is electrically connected to the scan line, one of the source and the drain of the first transistor is electrically connected to the data line, and the other of the source and the drain of the first transistor is electrically connected to the first node; the gate of the second transistor is electrically connected to the control line, one of the source and the drain of the second transistor is electrically connected to the second node, and the other of the source and the drain of the second transistor is electrically connected to the detection line; the first end of the capacitor is electrically connected to the first node, and the second end of the capacitor is electrically connected to the second node.

[0044] It should be noted that the pixel provided in the embodiment of the present application is only used as an example, and those skilled in the art can set the pixel according to specific needs. That is, the pixel provided in the embodiment of the present application not only includes the devices described above, but also includes other devices. For example, in order to further improve the control of the light emission of the light-emitting element, a transistor can be set between the first power supply and the driving transistor, and / or a transistor can be set between the second node and the light-emitting element.

[0045] In the embodiment provided in the present application, the driving transistor is used to control the driving current flowing through the driving transistor and the light-emitting element. The first transistor is used to provide the voltage provided by the data line to the first node under the control of the scanning signal provided by the scanning line; that is, the first transistor is used to provide the voltage provided by the data line to the gate of the driving transistor under the control of the scanning signal provided by the scanning line. The second transistor is used to provide the voltage provided by the detection line to the second node under the control of the control signal provided by the control line; that is, the second transistor is used to provide the voltage provided by the detection line to the drain of the driving transistor under the control of the control signal provided by the control line. The second transistor is also used to detect the second node electrically connected to the detection line under the control of the control signal provided by the control line.

[0046] In some embodiments provided in the present application, the driving transistor, the first transistor and the second transistor may be one or more of a low-temperature polysilicon thin film transistor, an oxide semiconductor thin film transistor or an amorphous silicon thin film transistor. The driving transistor, the first transistor and the second transistor may be transistors of the same type, thereby avoiding the difference between different types of transistors from affecting the pixel.

[0047] For details, see Figure 2 , Figure 2 Schematic diagram of an equivalent circuit of a pixel provided in an embodiment of the present application. Figure 2 As shown, the pixel provided in the embodiment of the present application includes a driving transistor T0, a first transistor T1, a second transistor T2, a capacitor Cst and a light-emitting element D. The gate of the driving transistor T0 is electrically connected to the first node g, one of the source and the drain of the driving transistor T0 is electrically connected to the first power supply VDD, and the other of the source and the drain of the driving transistor T0 is electrically connected to the second node s. The gate of the first transistor T1 is electrically connected to the scan line S1, one of the source and the drain of the first transistor T1 is electrically connected to the data line D1, and the other of the source and the drain of the first transistor T1 is electrically connected to the first node g. The gate of the second transistor T2 is electrically connected to the control line S2, one of the source and the drain of the second transistor T2 is electrically connected to the second node s, and the other of the source and the drain of the second transistor T2 is electrically connected to the detection line D2. The detection line D2 is electrically connected to the first end of the first switch element K1, and the second end of the first switch element K1 is electrically connected to the detection source ADC; the detection line D2 is electrically connected to the first end of the second switch element K2, and the second end of the second switch element K2 is electrically connected to the second node initial power supply Vpre. The first end of the capacitor Cst is electrically connected to the first node g, and the second end of the capacitor Cst is electrically connected to the second node s. The first end of the light-emitting element D is electrically connected to the second node s, and the second end of the light-emitting element D is electrically connected to the second power supply VSS.

[0048] The first switch element K1 is used to turn on or off the line between the detection line D2 and the detection source ADC. The second switch element K2 is used to turn on or off the line between the detection line D2 and the second node initial power supply Vpre. The detection source ADC is used to detect the voltage on the detection line D2. The second node initial power supply Vpre is used to provide a preset drain voltage to the detection line D2.

[0049] See also Figure 3 as well as Figure 2 , Figure 3 for Figure 2 The driving timing diagram of the equivalent circuit of the pixel shown in FIG. Figure 3 As shown, the driving timing of the pixel includes a pre-charging time period t1, a preset time period t2 and a detection time period t3. In the pre-charging time period t1, the scanning line S1 provides a scanning signal, so that the first transistor T1 is turned on, and the preset gate voltage provided by the data line D1 is supplied to the first node g, so that the voltage of the first node g is the preset gate voltage provided by the data line D1; the control line S2 provides a control signal, so that the second transistor T2 is turned on, and the first switch element K1 is turned off, the second switch element K2 is turned on, and the second node initial power supply Vpre provides a preset drain voltage to the second node s, so that the voltage of the second node s is equal to the preset drain voltage. In the preset time period t2, the scanning line S1 continues to provide a scanning signal, controls the first transistor T1 to be turned on, so that the voltage of the first node g is maintained at the preset gate voltage; the first switch element K1 is turned off and the second switch element K2 is turned off, and the control line S2 continues to provide a control signal, so that the second transistor T2 is turned on, so that the detection line D2 is in a floating state, at this time, the first power supply VDD raises the voltage of the second node s. In the detection time period t3, the scan line S1 continues to provide the scan signal to control the first transistor T1 to be turned on, so that the voltage of the first node g is still maintained at the preset gate voltage; the control line S2 continues to provide the control signal to turn on the second transistor T2, and the first switch element K1 is turned on and the second switch element K2 is turned off, so that the detection source ADC detects the voltage of the second node s based on the sampling signal Samp.

[0050] Step S2, initializing the voltage of the first node to obtain a first initial voltage, and initializing the voltage of the second node to obtain a second initial voltage, so as to turn on the driving transistor.

[0051] It should be noted that, in the embodiment of the present application, when the actual threshold voltage of the driving transistor is not detected, the first node g and the second node s need to be initialized multiple times. Moreover, the multiple initializations of the first node g are discontinuous, and the values ​​of the first node g initialized each time are different; the multiple initializations of the second node s are discontinuous, and the values ​​of the second node s initialized each time are the same. For example, after the first node g is initialized for the first time, other steps are performed, and after the other steps are completed, that is, after the first detection is completed, the first node g can be initialized for the second time, and the voltage of the first node g after the first initialization of the first node g is not equal to the voltage of the first node g after the first node g is initialized for the second time. For example, after the second node s is initialized for the first time, other steps are performed, and after the other steps are completed, that is, after the first detection is completed, the voltage of the second node s can be initialized for the second time, and the voltage of the second node g after the first initialization of the second node s is equal to the voltage of the second node s after the second initialization of the second node s.

[0052] Specifically, during the first detection, step S2 specifically includes: the scan line S1 provides a scan signal to turn on the first transistor T1, and the data line D1 provides a first preset voltage Vg(1) to the first node g, where the first preset voltage is the initial voltage of the first node, also known as the first initial voltage; the control line S2 provides a control signal to turn on the second transistor T2, and the detection line D2 provides a second preset voltage Vpre to the second node s, where the second preset voltage Vpre is the initial voltage of the second node, also known as the second initial voltage. When the nth detection is performed, step S2 specifically includes: the scan line S1 provides a scan signal to turn on the first transistor T1, and the data line D1 provides a first initial voltage Vg(n) to the first node g; wherein, Vg(n)=Vg(n-1)+Vth(n-1)′, n represents the number of detections, Vg(n) represents the first initial voltage in the nth detection, Vg(n-1) represents the first initial voltage in the n-1th detection, Vth(n-1)′ represents the threshold voltage characteristic value obtained in the n-1th detection, and n is an integer greater than 1.

[0053] In this embodiment, by setting the first preset voltage Vg(1), the first node g is initialized for the first time during the first detection, so that when the first node g is initialized for the first time, the first preset voltage Vg(1) is the first initial voltage of the first node g. When the first node g is detected for the nth time, the first node g is initialized for the nth time, and the voltage value required for the nth initialization of the first node g is calculated by the formula Vg(n)=Vg(n-1)+Vth(n-1)'. As for the initialization of the second node s, the voltage of the second node s after each initialization is the second preset voltage Vpre, and the second preset voltage Vpre can be set according to actual needs.

[0054] In some embodiments of the present application, the first preset voltage is greater than the second preset voltage, and the difference between the first preset voltage and the second preset voltage is not less than an actual threshold voltage of the driving transistor.

[0055] Step S3, controlling the first transistor and the second transistor to be turned on, and controlling the detection line to be in a floating state, so that the voltage of the first node is maintained at the first initial voltage, and the voltage of the second node is raised, and after a preset time period, the voltage of the second node is detected to obtain a detection voltage.

[0056] Specifically, step S3 specifically includes: the scan line S1 continues to provide a scan signal to control the first transistor T1 to be turned on, so that the voltage of the first node g is maintained at the first initial voltage; the first switch element K1 is turned off and the second switch element K2 is turned off, the control line S2 continues to provide a control signal, the second transistor T2 is turned on, so that the detection line D2 is in a floating state, at this time, the driving transistor T0 is turned on, and the first power supply VDD raises the voltage of the second node s. After a preset time period, the scan line S1 continues to provide a scan signal to control the first transistor T1 to be turned on, so that the voltage of the first node g is maintained at the first initial voltage; the control line S2 continues to provide a control signal, the second transistor T2 is turned on, the first switch element K1 is turned on, and the second switch element K2 is turned off, so that the detection source ADC detects the voltage of the second node s to obtain the detection voltage Vs.

[0057] In step S4, a reference threshold voltage is obtained according to the detection voltage and the first initial voltage.

[0058] Specifically, step S4 specifically includes: obtaining a reference threshold voltage according to the difference between the first initial voltage and the detection voltage; wherein V 参考 (n) = Vg(n) - Vs(n), V 参考 Vg(n) represents the reference threshold voltage obtained in the n-th detection, Vg(n) represents the first initial voltage in the n-th detection, and Vs(n) represents the detection voltage obtained in the n-th detection.

[0059] It should be noted that before determining the actual threshold voltage of the driving transistor, the detection voltage value obtained in each detection process is different.

[0060] In step S5 , the detection voltage is compared with the second initial voltage. If the detection voltage is equal to the second initial voltage, the reference threshold voltage is set as the actual threshold voltage of the driving transistor.

[0061] Furthermore, if the detection voltage is not equal to the second initial voltage, a third initial voltage is obtained according to the reference threshold voltage and the second initial voltage, and the process returns to step S2 . The third initial voltage is used to initialize the voltage of the first node in step S2 .

[0062] Among them, the detection voltage Vs of the second node s is compared with the second initial voltage Vpre. If the detection voltage Vs of the second node s is not equal to the second initial voltage Vpre, that is, in the threshold voltage detection method provided in the embodiment of the present application, step S1 is first executed, then step S2, then step S3, then step S4, and then step S5 is executed. If the detection voltage Vs of the second node s is not equal to the second initial voltage Vpre, then step S2, step S3, step S4 and step S5 are continued to be executed until the detection voltage Vs of the second node s is equal to the preset voltage Vpre, and the reference threshold voltage is set to the actual threshold voltage of the driving transistor T0.

[0063] Specifically, the step of obtaining the third initial voltage according to the reference threshold voltage and the second initial voltage specifically includes: obtaining the third initial voltage according to the sum of the reference threshold voltage and the second initial voltage, wherein Vg(n+1)=Vpre+V 参考 (n), Vg(n+1) represents the third initial voltage obtained by the nth detection, Vpre represents the second initial voltage in each detection, V 参考 (n) represents the reference threshold voltage obtained in the nth detection, and n is an integer greater than 1. Combined with the formula V 参考 Vg(n) = Vg(n) - Vs(n) and Vg(n+1) = Vpre + V 参考(n), it can be deduced that: Vg(n+1)=Vpre+Vg(n)-Vs(n). Therefore, according to the formula Vg(n+1)=Vpre+Vg(n)-Vs(n) and the formula Vg(n)=Vg(n-1)+Vth(n-1)', it can be deduced that: Vpre+Vg(n)-Vs(n)=Vg(n)+Vth(n)', and after transformation, it can be obtained that: Vpre-Vs(n)=Vth(n)'. Among them, Vpre represents the second initial voltage in each detection, Vs(n) represents the detection voltage obtained in the nth detection, and Vth(n)' represents the threshold voltage characteristic value obtained in the nth detection, that is, the threshold voltage characteristic value obtained in the nth detection is the second initial voltage minus the detection voltage obtained in the nth detection.

[0064] In some embodiments provided in the present application, the threshold voltage detection method further includes: after step S5, controlling the first transistor to be turned on to reset the voltage of the first node; controlling the second transistor to be turned on to reset the voltage of the second node. Figure 4 , Figure 4 for Figure 2 Another driving timing diagram of the equivalent circuit of the pixel shown in FIG. Figure 4As shown, the time periods involved in the pixel driving timing include a pre-charging time period t1, a preset time period t2, a detection time period t3, and a reset time period t4. In the pre-charging time period t1, the scanning line S1 provides a scanning signal, so that the first transistor T1 is turned on, and the preset gate voltage provided by the data line D1 is supplied to the first node g, so that the voltage of the first node g is the preset gate voltage provided by the data line D1; the control line S2 provides a control signal, so that the second transistor T2 is turned on, and the first switch element K1 is turned off, the second switch element K2 is turned on, and the second node initial power supply Vpre provides a preset drain voltage to the second node s, so that the voltage of the second node s is equal to the preset drain voltage. In the preset time period t2, the scanning line S1 continues to provide a scanning signal, controls the first transistor T1 to be turned on, so that the voltage of the first node g is maintained at the preset gate voltage; the first switch element K1 is turned off and the second switch element K2 is turned off, and the control line S2 continues to provide a control signal, so that the second transistor T2 is turned on, so that the detection line D2 is in a floating state, at this time, the first power supply VDD raises the voltage of the second node s. In the detection time period t3, the scan line S1 continues to provide a scan signal to control the first transistor T1 to be turned on, so that the voltage of the first node g is still maintained at the preset gate voltage; the control line S2 continues to provide a control signal to turn on the second transistor T2, and the first switch element K1 is turned on and the second switch element K2 is turned off, so that the detection source ADC detects the voltage of the second node s based on the sampling signal Samp. In the reset time period t4, the scan line S1 provides a scan signal to turn on the first transistor T1, and the data line D1 provides a first reset voltage to the first node g; the control line S2 provides a control signal to turn on the second transistor T2, and the detection line D2 provides a second reset voltage to the second node s.

[0065] It should be noted that, in the threshold voltage detection method provided by the present application, the first preset voltage of the first node and the second preset voltage of the second node respectively initialized in the first detection are both settable, rather than the voltage data displayed when the pixel is displayed. In order to avoid abnormal display of the detection row after the detection is completed, some embodiments of the present application reset the voltage of the first node and the voltage of the second node after step S5, and can write the display voltage data back to the state before the detection.

[0066] See also Figure 1 , Figure 2 as well as Figure 5 , Figure 5 Based on Figure 1The flowchart shown is a driving timing diagram for the first detection. In the first detection, the threshold voltage characteristic value Vth(1)' obtained in the first detection is Vpre-Vs(1). If the value of the first initial voltage Vg(1) is greater than the value of the second initial voltage Vpre, and the difference between the first initial voltage Vg(1) and the second initial voltage Vpre is greater than the actual threshold voltage of the driving transistor T0, then the value of the detection voltage Vs(1) obtained in the first detection is greater than the value of the second initial voltage Vpre, so the value of Vth(1)' is less than zero. Since Vs(1) obtained in the first detection is not equal to Vpre, a second detection is required.

[0067] See also Figure 1 , Figure 2 as well as Figure 6 , Figure 6 Based on Figure 1 The flowchart shown is a driving timing diagram for the second detection. In the second detection, the first initial voltage is determined by the previous reference threshold voltage and the second initial voltage, that is, the first initial voltage Vg(2) of the second detection = Vpre + V 参考 (1) = Vpre + Vg(1) - Vs(1) = Vpre - Vs(1) + Vg(1) = Vth(1)' + Vg(1). Since the value of Vth(1)' is less than zero, it can be determined from the relationship Vg(2) = Vth(1)' + Vg(1) that the value of Vg(2) is less than Vg(1), so the first initial voltage in the second detection is less than the first initial voltage in the first detection. The second initial voltage is constant in each detection, that is, the second initial voltage is always Vpre. Therefore, when the second detection consumes the same detection time as the first detection, the detection voltage Vs(2) obtained by the second detection is less than Vs(1).

[0068] See also Figure 1 , Figure 2 as well as Figure 7 , Figure 7 Based on Figure 1 The flowchart shown is a schematic diagram of the driving timing of the nth detection. Similarly, it can be known that in the nth detection, Vg(n)=Vpre+V 参考(n-1)=Vpre+Vg(n-1)-Vs(n-1)=Vpre-Vs(n-1)+Vg(n-1)=Vth(n-1)'+Vg(n-1), and the detection voltage Vs(n) of the second node is detected. If Vpre=Vs(n), then Vth(n)'=Vpre-Vs(n)=0, and the detection voltage Vs(n) will no longer rise. Even if Vg(n+1) continues to be detected, the value of Vs(n+1) will be the same as the value of Vs(n), thereby completing the actual threshold voltage detection of the driving transistor T0, and the actual threshold voltage=Vg(n)-Vpre.

[0069] In summary, in this embodiment, the gate-source voltage of the driving transistor is reduced from a state greater than the threshold voltage to a state equal to the threshold voltage through a voltage reduction iteration method combined with a new detection process and a control timing.

[0070] In some embodiments provided in the present application, the detection time period during which the threshold voltage detection method performs steps S2 to S5 is located in the vertical blanking area.

[0071] It should be noted that the vertical blank area (V-Blank area) refers to the time period from the last line of display data of the current frame of the display device to the first line of display data of the next frame. The length of the vertical blank area depends on the resolution, refresh rate and charging timing of the display device. For example, for a 4K and 120HZ active matrix organic light-emitting diode display device, the length of the vertical blank area is about 333 microseconds.

[0072] The threshold voltage detection method provided in the present application reduces the gate-source voltage of the driving transistor from a state greater than the threshold voltage to a state equal to the threshold voltage by means of voltage reduction iteration, combined with a new detection process and control timing. Since the process of reducing the gate-source voltage from a state greater than the threshold voltage to a state equal to the threshold voltage is continuously iteratively updated, the time of a single detection can be greatly shortened, and an iterative update can be completed in each vertical blank area, thereby completing the detection of the actual threshold voltage of the driving transistor without affecting the normal display of the display device.

[0073] See also Figure 8 , Figure 8 The structure diagram of the threshold voltage detection device provided in the embodiment of the present application. The threshold voltage detection device 100 includes:

[0074] A pixel 101, the pixel 101 includes a driving transistor, a first transistor, a second transistor, a capacitor and a light-emitting element; the gate of the driving transistor is electrically connected to the first node, one of the source and the drain of the driving transistor is electrically connected to the first power supply, and the other of the source and the drain of the driving transistor is electrically connected to the second node; the gate of the first transistor is electrically connected to the scan line, one of the source and the drain of the first transistor is electrically connected to the data line, and the other of the source and the drain of the first transistor is electrically connected to the first node; the gate of the second transistor is electrically connected to the control line, one of the source and the drain of the second transistor is electrically connected to the second node, and the other of the source and the drain of the second transistor is electrically connected to the detection line; the first end of the capacitor is electrically connected to the first node, and the second end of the capacitor is electrically connected to the second node;

[0075] An initialization module 102, the initialization module 102 is used to initialize the voltage of the first node to obtain a first initial voltage, and initialize the voltage of the second node to obtain a second initial voltage, so as to turn on the driving transistor;

[0076] A detection module 103, the detection module 103 is used to control the voltage of the first node to be maintained at the first initial voltage, so that the voltage of the second node is raised based on the first power supply, and after a preset time period, the voltage of the second node is detected to obtain a detection voltage;

[0077] A calculation module 104, the calculation module 104 is used to obtain a reference threshold voltage according to the detection voltage and the first initial voltage;

[0078] The comparison module 105 is configured to compare the detection voltage with the second initial voltage.

[0079] The storage module 106 is used to store a reference threshold voltage, and if the detection voltage is equal to the second initial voltage, the reference threshold voltage is stored as the actual threshold voltage of the driving transistor.

[0080] In some embodiments of the present application, the threshold voltage detection device further includes:

[0081] A reset module is used to reset the voltage of the first node and the voltage of the second node after the detection is completed.

[0082] The present application provides a threshold voltage detection device, which reduces the gate-source voltage of the driving transistor from a state greater than the threshold voltage to a state equal to the threshold voltage by means of voltage reduction iteration, combined with a new detection process and control timing. Since the process of reducing the gate-source voltage from a state greater than the threshold voltage to a state equal to the threshold voltage is continuously iteratively updated, the time of a single detection can be greatly shortened, and an iterative update can be completed in each vertical blank area, thereby completing the detection of the actual threshold voltage of the driving transistor without affecting the normal display of the display device.

[0083] The embodiment of the present application further provides a display device, which includes the threshold voltage detection device described above. The details can be referred to the above description and will not be repeated here.

[0084] The display device provided in the present application reduces the gate-source voltage of the driving transistor from a state greater than the threshold voltage to a state equal to the threshold voltage through an iterative voltage reduction method combined with a new detection process and a control timing. Since the process of reducing the gate-source voltage from a state greater than the threshold voltage to a state equal to the threshold voltage is continuously iteratively updated, the time of a single detection can be greatly shortened, and an iterative update can be completed in each vertical blank area, thereby completing the detection of the actual threshold voltage of the driving transistor without affecting the normal display of the display device.

[0085] The above are merely embodiments of the present application and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A threshold voltage detection method, characterized in that: include: Step S1, providing a pixel, the pixel comprising a driving transistor, a first transistor, a second transistor, a capacitor and a light-emitting element; the gate of the driving transistor is electrically connected to the first node, one of the source and the drain of the driving transistor is electrically connected to the first power supply, and the other of the source and the drain of the driving transistor is electrically connected to the second node; the gate of the first transistor is electrically connected to the scan line, one of the source and the drain of the first transistor is electrically connected to the data line, and the other of the source and the drain of the first transistor is electrically connected to the first node; the gate of the second transistor is electrically connected to the control line, one of the source and the drain of the second transistor is electrically connected to the second node, and the other of the source and the drain of the second transistor is electrically connected to the detection line; the first end of the capacitor is electrically connected to the first node, and the second end of the capacitor is electrically connected to the second node; Step S2, initializing the voltage of the first node to obtain a first initial voltage, and initializing the voltage of the second node to obtain a second initial voltage, so as to turn on the driving transistor; Step S3, controlling the first transistor and the second transistor to be turned on, and controlling the detection line to be in a floating state, so that the voltage of the first node is maintained at the first initial voltage, and the voltage of the second node is raised, and after a preset time period, the voltage of the second node is detected to obtain a detection voltage; Step S4, obtaining a reference threshold voltage according to a difference between the detection voltage and the first initial voltage; Step S5, comparing the detection voltage with the second initial voltage, and if the detection voltage is equal to the second initial voltage, setting the reference threshold voltage as the actual threshold voltage of the driving transistor; The threshold voltage detection method further includes: If the detection voltage is not equal to the second initial voltage, a third initial voltage is obtained according to the sum of the reference threshold voltage and the second initial voltage, and the process returns to step S2 . The third initial voltage is used to initialize the voltage of the first node in step S2 .

2. The threshold voltage detection method according to claim 1, characterized in that: The step S4 specifically includes: V 参考 (n)=Vg(n)-Vs(n), V 参考 Vg(n) represents the reference threshold voltage obtained in the n-th detection, Vg(n) represents the first initial voltage in the n-th detection, and Vs(n) represents the detection voltage obtained in the n-th detection.

3. The threshold voltage detection method according to claim 1, characterized in that: The step of obtaining the third initial voltage according to the sum of the reference threshold voltage and the second initial voltage specifically includes: Vg(n+1)=Vpre+V 参考 (n), Vg(n+1) represents the third initial voltage obtained by the nth detection, Vpre represents the second initial voltage in each detection, and n is an integer greater than 1.

4. The threshold voltage detection method according to claim 1, characterized in that: When detecting for the first time, step S2 specifically includes: The scan line provides a scan signal to turn on the first transistor, and the data line provides a first preset voltage to the first node; the control line provides a control signal to turn on the second transistor, and the detection line provides a second preset voltage to the second node.

5. The threshold voltage detection method according to claim 4, characterized in that: The first preset voltage is greater than the second preset voltage, and a difference between the first preset voltage and the second preset voltage is not less than the actual threshold voltage.

6. The threshold voltage detection method according to claim 1, characterized in that: The threshold voltage detection method further includes: After step S5, the first transistor is controlled to be turned on to reset the voltage of the first node; and the second transistor is controlled to be turned on to reset the voltage of the second node.

7. The threshold voltage detection method according to claim 1, characterized in that: In the threshold voltage detection method, the detection time period for executing the steps S2 to S5 is located in the vertical blank area.

8. A threshold voltage detection device, characterized in that: A threshold voltage detection method for implementing any one of claims 1 to 7, comprising: A pixel, the pixel comprising a driving transistor, a first transistor, a second transistor, a capacitor and a light-emitting element; the gate of the driving transistor is electrically connected to the first node, one of the source and the drain of the driving transistor is electrically connected to the first power supply, and the other of the source and the drain of the driving transistor is electrically connected to the second node; the gate of the first transistor is electrically connected to the scan line, one of the source and the drain of the first transistor is electrically connected to the data line, and the other of the source and the drain of the first transistor is electrically connected to the first node; the gate of the second transistor is electrically connected to the control line, one of the source and the drain of the second transistor is electrically connected to the second node, and the other of the source and the drain of the second transistor is electrically connected to the detection line; the first end of the capacitor is electrically connected to the first node, and the second end of the capacitor is electrically connected to the second node; an initialization module, the initialization module being used to initialize the voltage of the first node to obtain a first initial voltage, and to initialize the voltage of the second node to obtain a second initial voltage, so as to turn on the driving transistor; a detection module, the detection module being used to control the voltage of the first node to be maintained at the first initial voltage, so that the voltage of the second node is raised based on the first power supply, and after a preset time period, detecting the voltage of the second node to obtain a detection voltage; A calculation module, the calculation module is used to obtain a reference threshold voltage according to a difference between the detection voltage and the first initial voltage; a comparison module, the comparison module being used to compare the detection voltage with the second initial voltage; a storage module, the storage module being used to store the reference threshold voltage, and if the detection voltage is equal to the second initial voltage, storing the reference threshold voltage as the actual threshold voltage of the driving transistor; A return initialization module is used to obtain a third initial voltage based on the sum of the reference threshold voltage and the second initial voltage if the detection voltage is not equal to the second initial voltage, and return to step S2. The third initial voltage is used to initialize the voltage of the first node in step S2.

9. The threshold voltage detection device according to claim 8, characterized in that: The threshold voltage detection device also includes: A reset module, wherein the reset module is used to reset the voltage of the first node and reset the voltage of the second node after step S5.

10. A display device, characterized in that: The display device comprises the threshold voltage detection device according to any one of claims 8 to 9.

Images