8T2C enhanced / depletion type driving tube threshold voltage compensation circuit and method

Abstract

The invention relates to an 8T2C enhanced / depletion type driving tube threshold voltage compensation circuit and method, belongs to the technical field of display, and solves the problems of low pixel compensation rate and complex control in the prior art. Comprising a current-type light-emitting diode, a switching tube unit, a driving tube and a compensation capacitor unit, the drain electrode of the first switch tube is connected with second reference voltage; the drain electrode of the second switch tube is connected with the power voltage and the source electrode is connected with the drain electrode of the driving tube; the drain of the third switch tube is connected with external input data, and the source is connected with the driving tube grid; the drain electrode of the fourth switch tube is connected with the power voltage and the source electrode is connected with the drain electrode of the driving tube; the source of the fifth switch tube is connected with first reference voltage, and the drain is connected with the source of the driving tube; the source electrode of the sixth switch tube is grounded, and the drain electrode is connected with the anode of the current-type light-emitting diode; the drain electrode of the seventh switch tube is connected with the source electrode of the driving tube. The objective of achieving a relatively high pixel compensation rate by utilizing simple control is achieved.

Description

Technical Field

[0001] The present invention relates to the field of microdisplay technology, and in particular to an 8T2C enhancement / depletion drive tube threshold voltage compensation circuit and method. Background Art

[0002] AMOLED (Active Matrix Organic Light Emitting Diode) display technology is widely used in high-end display devices such as smartphones and TVs due to its advantages such as bright colors, high contrast and wide viewing angle. Compared with general a-Si:H TFT, Oxide (IGZO) TFT and LTPS TFT have higher mobility and better stability, and are more suitable for use in AMOLED displays.

[0003] However, due to the limitations of the crystallization process, when making LTPS TFTs on large-area glass substrates, TFTs at different locations often have non-uniformity in electrical parameters such as threshold voltage and mobility. This non-uniformity will be converted into current differences and brightness differences in OLED display devices and will be perceived by the human eye, which is the mura phenomenon. Although the process uniformity of oxide TFTs is good, its threshold voltage will drift under long-term pressure and high temperature. Due to different display images, the threshold drift of TFTs in different parts of the panel is different, which will cause display brightness differences. Since this difference is related to the previously displayed image, it often appears as a residual image phenomenon, which is commonly known as an afterimage.

[0004] The above problems are difficult to completely overcome in terms of technology and need to be solved through various compensation technologies in circuit design. The existing compensation technologies have the problems of low pixel compensation rate, large number of clock signal lines and complex control. Summary of the invention

[0005] In view of the above analysis, the embodiments of the present invention aim to provide an 8T2C enhancement / depletion drive tube threshold voltage compensation circuit and method to solve the problems of low pixel compensation rate, large number of clock signal lines and complex control in the prior art.

[0006] On the one hand, an embodiment of the present invention provides an 8T2C enhancement / depletion mode driver threshold voltage compensation circuit, including:

[0007] A current-type light-emitting diode, a switch tube unit, a driving tube, and a compensation capacitor unit; wherein the switch tube unit includes first to seventh switch tubes; and the compensation capacitor unit includes a first compensation capacitor and a second compensation capacitor;

[0008] The drain of the first switch tube is connected to the second reference voltage, and the source is connected to the gate of the driving tube; the drain of the second switch tube is connected to the power supply voltage, and the source is connected to the drain of the driving tube; the drain of the third switch tube is connected to the external input data, and the source is connected to the gate of the driving tube; the drain of the fourth switch tube is connected to the power supply voltage, and the source is connected to the drain of the driving tube; the source of the fifth switch tube is connected to the first reference voltage, and the drain is connected to the source of the driving tube; the source of the sixth switch tube is grounded, and the drain is connected to the anode of the current-type light-emitting diode; the drain of the seventh switch tube is connected to the source of the driving tube, and the source is connected to the anode of the current-type light-emitting diode; the cathode of the current-type light-emitting diode is grounded;

[0009] One end of the first compensation capacitor is connected to the gate electrode of the driving tube, and the other end is connected to the source electrode of the driving tube; one end of the second compensation capacitor is connected to the source electrode of the driving tube, and the other end is connected to the power supply voltage.

[0010] A further improvement based on the above scheme further includes first to fourth clock signals input from the outside; wherein,

[0011] The first clock signal controls the on and off of the fifth switch tube and the sixth switch tube;

[0012] The second clock signal controls the on and off of the first switch tube and the fourth switch tube;

[0013] The third clock signal controls the on and off of the third switch tube;

[0014] The fourth clock signal controls the on and off of the second switch tube and the seventh switch tube.

[0015] Based on a further improvement of the above solution, the difference between the second reference voltage and the driver tube threshold is greater than the first reference voltage.

[0016] Based on the further improvement of the above solution, the power supply voltage is a 15V DC voltage.

[0017] Based on a further improvement of the above solution, the first to seventh switch tubes and the drive tubes are all N-type.

[0018] On the other hand, an embodiment of the present invention provides a 8T2C enhancement / depletion drive tube threshold voltage compensation method, which includes: an initialization stage, a threshold voltage compensation stage, a data input stage, and a light-emitting stage; wherein:

[0019] The initialization stage is used to obtain the initial states of the first compensation capacitor and the second compensation capacitor based on the first reference voltage, and discharge the terminal charge of the current-type light-emitting diode;

[0020] The threshold voltage compensation stage is used to measure and compensate the driver tube threshold voltage based on the second reference voltage and the power supply voltage;

[0021] The data input stage is used to calculate the source voltage of the driving tube based on the external input data;

[0022] The light emitting stage is used to obtain the driving current of the current-type light emitting diode based on the source voltage of the driving tube.

[0023] Based on the further improvement of the above method, the initialization stage includes:

[0024] The first clock signal is at a high level, and the fifth and sixth switch tubes are turned on; the second to fourth clock signals are at a low level, and the first to fourth and seventh switch tubes are turned off;

[0025] The upper end of the first compensation capacitor is suspended, and the lower end voltage is the first reference voltage; the upper end of the second compensation capacitor is the power supply voltage, and the lower end is the first reference voltage; the anode of the current-type light-emitting diode is grounded to discharge the terminal charge.

[0026] Based on the further improvement of the above method, the threshold voltage compensation stage includes:

[0027] The second clock signal is at a high level, and the first and fourth switch tubes are turned on; the first, third, and fourth clock signals are at a low level, and the second, third, fifth to seventh switch tubes are turned off;

[0028] The gate of the driving tube is connected to the second reference voltage, and the driving tube is turned on based on the voltage difference between the gate and the source of the driving tube; after the driving tube is turned on, the source of the driving tube is charged to the difference between the second reference voltage and the threshold voltage of the driving tube based on the power supply voltage, and the driving tube is turned off; the threshold voltage is measured and compensated by using the source follower structure.

[0029] Based on the further improvement of the above method, the data input stage includes:

[0030] The third clock signal is at a high level, and the third switch tube is turned on; the first, second, and fourth clock signals are at a low level, and the first, second, fourth to seventh switch tubes are turned on;

[0031] Connect the gate of the driver tube to the voltage corresponding to the external input data, and use the following formula to get the source voltage of the driver tube in the data input stage:

[0032] V S3 =(V DATA -V ref2 )*C2 / (c1+C2)+V ref2 -V th_T8

[0033] Among them, V S3 Represents the source voltage of the driver tube during the data input phase, V DATA Indicates the voltage corresponding to the external input data, V ref2 Represents the second reference voltage, Vth_T8 represents the threshold voltage of the driving tube, C1 represents the first compensation capacitor, and C2 represents the second compensation capacitor.

[0034] Based on the further improvement of the above method, the light emitting stage includes:

[0035] Only the fourth clock signal is at a high level, the second switch tube and the seventh switch tube are turned on; the first to third clock signals are at a low level, the first, third to sixth switch tubes are turned off;

[0036] The power supply voltage is connected to the anode of the current-type light-emitting diode through the second switch tube, the drive tube, and the seventh switch tube in sequence; the source voltage of the drive tube in the light-emitting stage is obtained using the following formula:

[0037] V S4 =VDD*(R T7 +R diode ) / (R T2 +R T8 +R T7 +R diode )

[0038] Among them, V S4 Indicates the source voltage of the driving tube during the light-emitting stage, VDD indicates the power supply voltage, R T2 Represents the internal resistance of the second switch tube, R T8 Represents the internal resistance of the driver tube, R T7 Represents the internal resistance of the seventh switch tube, R diode Indicates the internal resistance of a current-mode light-emitting diode;

[0039] Based on the driving tube source voltage in the data input stage and the driving tube source voltage in the light-emitting stage, the driving tube gate voltage in the light-emitting stage is obtained, and the driving tube gate-source voltage difference in the light-emitting stage is obtained using the following formula:

[0040]

[0041] Where V gs_T8 Represents the gate-source voltage difference of the driver tube, V G4 Indicates the gate voltage of the driving tube during the light-emitting stage, V S4 Indicates the source voltage of the driving tube during the light-emitting stage, V DATA Indicates the voltage corresponding to the external input data, V th_T8 Indicates the threshold voltage of the driver tube;

[0042] Based on the gate-source voltage difference of the driving tube and the threshold voltage of the driving tube during the light-emitting stage, the driving current of the current-type light-emitting diode is obtained using the following formula:

[0043]

[0044] Where, I represents the driving current of the current-mode light-emitting diode, μ represents the electron mobility of the driver tube, C ox represents the gate dielectric capacitance of the driving tube, W represents the channel width of the driving tube, and L represents the channel length of the driving tube;

[0045] The light emitting diode is driven based on the driving current to emit light with corresponding brightness.

[0046] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0047] 1. The circuit of the present invention includes 8 driving tubes and 2 capacitors, and the circuit structure is relatively simple; when implemented, 4 external input clock signals are used, and the control is simple.

[0048] 2. It can simultaneously meet the threshold voltage compensation of both enhancement type and depletion type driver tubes, and has a wide range of applications.

[0049] 3. The initialization operation ensures that each compensation capacitor and current-mode light-emitting diode are in their respective initial states before being refreshed, and will not be affected by the residual charge of the previous frame, so that the brightness of the current-mode light-emitting diode will not be affected by the brightness of the previous frame, which is beneficial to improving the display contrast.

[0050] 4. The pixel compensation rate can reach 99.95%, the compensation efficiency is very good, which greatly improves the stability of the display brightness of the current-type light-emitting diode.

[0051] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] The accompanying drawings are only used for the purpose of illustrating specific embodiments and are not to be considered as limiting the present invention. In the entire drawings, the same reference symbols represent the same components;

[0053] Figure 1 An 8T2C enhancement / depletion type driver threshold voltage compensation circuit shown in one embodiment of the present invention;

[0054] Figure 2 A schematic diagram of a clock signal according to an embodiment of the present invention;

[0055] Figure 3 A schematic diagram of the initialization phase of an embodiment of the present invention;

[0056] Figure 4 A schematic diagram of a threshold voltage compensation stage shown in an embodiment of the present invention;

[0057] Figure 5 A schematic diagram of a data input stage according to an embodiment of the present invention;

[0058] Figure 6 A schematic diagram of the light-emitting phases according to an embodiment of the present invention;

[0059] Figure 7 A circuit simulation waveform diagram shown in one embodiment of the present invention;

[0060] Figure 8 This is a driving tube simulation characteristic curve diagram shown in one embodiment of the present invention. DETAILED DESCRIPTION

[0061] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0062] The main application of threshold voltage compensation circuit is in display circuit, especially in the design of display panels such as AMOLED and LCD. Its core purpose is to ensure that each pixel in the display can maintain consistent brightness and color, thereby improving the display effect and extending the service life of the screen. Specific application areas include:

[0063] 1. The pixels in an active matrix organic light-emitting diode (AMOLED) display are made of organic materials, the brightness of which decays over time. Changes in the threshold voltage directly affect the drive current, which in turn affects the brightness and color performance of the pixel. The function of the threshold voltage compensation circuit is to monitor and compensate for the threshold voltage changes of each pixel in real time to cope with the aging of the OLED material, temperature changes, and changes caused by the drive current, ensuring consistent brightness of each pixel and preventing uneven display.

[0064] 2. LCD displays also use thin film transistors (TFT) to drive pixel display panels, and they also encounter the problem of threshold voltage drift. The TFT material of the LCD will also cause the threshold voltage to change as the working time changes, thus affecting the driving and brightness of the liquid crystal pixels. In order to maintain the consistency of color and brightness, especially in high-resolution and large-size displays, the threshold voltage compensation circuit is used to compensate for the threshold voltage drift of the TFT to ensure that the display effect is not affected under long-term use.

[0065] For specific products, in high-resolution display panels such as mobile phones, tablets, TVs, and monitors, because the number of pixels is very large, this means that changes in threshold voltage will have a more significant impact on the display effect. Especially after the display has been running for a long time, due to factors such as temperature changes, ambient humidity, and current drive, threshold voltage drift may cause uneven brightness of some pixels, affecting picture quality. In some emerging flexible displays and wearable devices, they will be subject to more complex stress and temperature changes, and the combined effects of these mechanical stresses, vibrations and shocks, temperature and external forces require compensation circuits to ensure that the display effect remains consistent under long-term use, regardless of how the external form of the device changes. In addition, compensation circuits are also needed in automotive displays and VR / AR devices.

[0066] A specific embodiment of the present invention discloses an 8T2C enhancement / depletion mode driver threshold voltage compensation circuit, such as Figure 1 As shown. Includes:

[0067] A current-type light-emitting diode, a switch tube unit, a driving tube T8, and a compensation capacitor unit; wherein the switch tube unit includes first to seventh switch tubes; and the compensation capacitor unit includes a first compensation capacitor C1 and a second compensation capacitor C2;

[0068] The drain of the first switch tube T1 is connected to the second reference voltage V ref2 , the source is connected to the gate of the driving tube; the drain of the second switch tube T2 is connected to the power supply voltage VDD, and the source is connected to the drain of the driving tube; the drain of the third switch tube T3 is connected to the external input data V DATA , the source is connected to the gate of the driving tube; the drain of the fourth switch tube T4 is connected to the power supply voltage, and the source is connected to the drain of the driving tube; the source of the fifth switch tube T5 is connected to the first reference voltage V ref1 , the drain is connected to the source of the driving tube; the source of the sixth switch tube T6 is grounded, and the drain is connected to the anode of the current-type light-emitting diode; the drain of the seventh switch tube T7 is connected to the source of the driving tube, and the source is connected to the anode of the current-type light-emitting diode; the cathode of the current-type light-emitting diode is grounded;

[0069] One end of the first compensation capacitor is connected to the gate electrode of the driving tube, and the other end is connected to the source electrode of the driving tube; one end of the second compensation capacitor is connected to the source electrode of the driving tube, and the other end is connected to the power supply voltage.

[0070] It is worth noting that the switch tube is used to turn on the circuit, and the driver tube is used to provide a saturated drive current to light up the current-type light-emitting diode.

[0071] Exemplarily, the first compensation capacitor C1 and the second compensation capacitor C2 are both 1pF; the first compensation capacitor and the second compensation capacitor can increase the charge retention time. The first to seventh switch tubes and driver tubes are all N-type; using all N-type tubes makes the circuit simpler when it is actually prepared on a large area. The power supply voltage and external input data are both 15V DC voltage. The difference between the second reference voltage and the driver tube threshold is greater than the first reference voltage. Optionally, the first reference voltage is -5V and the second reference voltage is 0V.

[0072] In a possible implementation, the current-mode light-emitting diode is made of organic material, so that the overall pixel block and the surrounding compensation circuit have better flexibility after the actual array tape-out industrial application.

[0073] In addition, it also includes the first to fourth clock signals input from the outside; wherein,

[0074] The first clock signal controls the on and off of the fifth switch tube and the sixth switch tube;

[0075] The second clock signal controls the on and off of the first switch tube and the fourth switch tube;

[0076] The third clock signal controls the on and off of the third switch tube;

[0077] The fourth clock signal controls the on and off of the second switch tube and the seventh switch tube.

[0078] like Figure 2 As shown, in a single cycle, the first to fourth clock signals are at a high level in sequence. For example, the high level of the clock signal is 15V, the low level is -15V, and the duration of each stage is 100 microseconds.

[0079] Another specific embodiment of the present invention discloses a 8T2C enhancement / depletion mode driver threshold voltage compensation method, the steps comprising:

[0080] S1: an initialization stage, for obtaining the initial states of the first compensation capacitor and the second compensation capacitor based on the first reference voltage, and discharging the terminal charge of the current-type light-emitting diode;

[0081] S2: a threshold voltage compensation stage, used to measure and compensate the driver tube threshold voltage based on the second reference voltage and the power supply voltage;

[0082] S3: data input stage, used to calculate the source voltage of the driving tube based on the external input data;

[0083] S4: a light emitting stage, which is used to obtain a driving current of a current-type light emitting diode based on the source voltage of the driving tube.

[0084] Specifically, if Figure 3 As shown, the initialization phase includes:

[0085] The first clock signal Scan1 is at a high level, and the fifth and sixth switch tubes are turned on; the second to fourth clock signals are at a low level, and the first to fourth and seventh switch tubes are turned off;

[0086] The upper end of the first compensation capacitor is suspended, and the voltage at the lower end is the first reference voltage; the upper end of the second compensation capacitor is the power supply voltage, and the lower end is the first reference voltage, so that the first compensation capacitor and the second compensation capacitor are in the initial state; the anode of the current-type light-emitting diode is grounded to discharge the terminal charge.

[0087] It is worth noting that the initialization stage ensures that the first compensation capacitor, the second compensation capacitor and the current-type light-emitting diode are in their respective initial states before each refresh, so that the compensation and capacitive coupling performed by the first compensation capacitor and the second compensation capacitor will not be affected by the residual charge of the previous frame, which is beneficial to improving the display contrast and solves the afterimage phenomenon in display panels with lower frequency and shorter product life cycle.

[0088] Specifically, if Figure 4 As shown, the threshold voltage compensation stage includes:

[0089] The second clock signal Scan2 is at a high level, and the first switch tube and the fourth switch tube are turned on; the first, third, and fourth clock signals are at a low level, and the second, third, fifth to seventh switch tubes are turned off;

[0090] The gate of the driving tube is connected to the second reference voltage, and the gate of the driving tube is biased to the reference voltage 0V; by using the coupling effect of the capacitor, the voltage difference between the gate and the source of the driving tube is 5V, and the driving tube is turned on based on the voltage difference between the gate and the source of the driving tube; after the driving tube is turned on, the source of the driving tube is charged to the second reference voltage V based on the power supply voltage ref2 and the driver threshold voltage V th_T8 The difference between the threshold voltage and the source follower structure is used to measure and compensate the threshold voltage.

[0091] It is worth noting that when the driver threshold voltage V th_T8 When it is positive, the voltage of the driver tube source after charging is greater than the voltage of the driver tube gate; when the driver tube threshold voltage V th_T8 When it is negative, the voltage of the driver tube source after charging is less than the voltage of the driver tube gate, making this circuit applicable to both enhancement type and depletion type driver tubes.

[0092] Specifically, if Figure 5 As shown, the data input stage includes:

[0093] The third clock signal Scan3 is at a high level, and the third switch tube is turned on; the first, second, and fourth clock signals are at a low level, and the first, second, fourth to seventh switch tubes are turned on;

[0094] Connect the gate of the driver tube to the voltage corresponding to the external input data, and use the following formula to get the source voltage of the driver tube in the data input stage:

[0095] V S3 =(V DATA -V ref2 )*C2 / (C1+C2)+V ref2 -V th_T8

[0096] Among them, V S3 Represents the source voltage of the driver tube during the data input phase, V DATA Indicates the voltage corresponding to the external input data, V ref2 Represents the second reference voltage, V th_T8 represents the threshold voltage of the driving tube, C1 represents the first compensation capacitor, and C2 represents the second compensation capacitor.

[0097] When C1 and C2 are equal, When V ref2 When is 0, we can get

[0098] Specifically, if Figure 6 As shown, the light emitting stage includes:

[0099] Only the fourth clock signal Scan4 is at a high level, the second switch tube and the seventh switch tube are turned on; the first to third clock signals are at a low level, the first, third to sixth switch tubes are turned off;

[0100] The power supply voltage is connected to the anode of the current-type light-emitting diode through the second switch tube, the drive tube, and the seventh switch tube in sequence; based on the voltage division principle, the source voltage of the drive tube in the light-emitting stage is obtained using the following formula:

[0101] V S4 =VDD*(R T7 +R diode ) / (R T2 +R T8 +R T7 +R diode )

[0102] Among them, V S4 Indicates the source voltage of the driving tube during the light-emitting stage, VDD indicates the power supply voltage, R T2 Represents the internal resistance of the second switch tube, R T8 Represents the internal resistance of the driver tube, R T7 Represents the internal resistance of the seventh switch tube, R diodeIndicates the internal resistance of a current-mode light-emitting diode;

[0103] Furthermore, based on the source voltage of the driving tube in the data input stage and the source voltage of the driving tube in the light-emitting stage, according to the coupling principle of capacitance, the gate voltage V of the driving tube in the light-emitting stage is obtained by the following formula: G4 :

[0104]

[0105] Furthermore, the gate-source voltage difference of the driving tube in the light-emitting stage is obtained using the following formula:

[0106]

[0107] Where V gs_T8 Represents the gate-source voltage difference of the driver tube, V G4 Indicates the gate voltage of the driving tube during the light-emitting stage, V S4 Indicates the source voltage of the driving tube during the light-emitting stage, V DATA Indicates the voltage corresponding to the external input data, V th_T8 Indicates the threshold voltage of the driver tube;

[0108] Furthermore, based on the gate-source voltage difference of the driving tube and the threshold voltage of the driving tube in the light-emitting stage, the driving current of the current-type light-emitting diode is obtained using the following formula:

[0109]

[0110] Where, I represents the driving current of the current-mode light-emitting diode, μ represents the electron mobility of the driver tube, C ox represents the gate dielectric capacitance of the driving tube, W represents the channel width of the driving tube, and L represents the channel length of the driving tube;

[0111] It is worth noting that the threshold voltage of the driver tube has been eliminated in the driving current formula of the current-mode light-emitting diode. Therefore, the change of the threshold voltage of the driver tube no longer affects the magnitude of the driving current of the current-mode light-emitting diode.

[0112] The current-type light-emitting diode is driven based on the driving current to emit light with corresponding brightness.

[0113] Circuit simulation waveform is as follows Figure 7 As shown, the driving tube simulation characteristic curve is as follows Figure 8 As shown. Through simulation, the driving current capture data is shown in Table 1, which is from the simulation 550.0066us; the pixel compensation rate of the compensation circuit and the corresponding compensation method of this embodiment is shown in Table 2, which is 99.59%, and a very high pixel compensation rate can be achieved.

[0114] Table 1 Drive current capture data

[0115] Threshold voltage drift Driver tube TFT drive current data capture -2.0V 3.089207001858414e-6A -1.0V 3.0805272009509287e-6A 0V 3.070974188009309e-6A 1.0V 3.0602252763653276e-6A 2.0V 3.0462350933476197e-6A

[0116] Table 2 Pixel compensation rate

[0117]

[0118]

[0119] Compared with the prior art, the circuit provided in this embodiment includes 8 driving tubes and 2 capacitors, and the circuit structure is relatively simple; in the specific implementation, 4 external input clock signals are used, and the control is simple; the compensation method of this embodiment can simultaneously meet the threshold voltage compensation of both enhanced and depletion type driving tubes, and has a wide range of applications; the initialization stage can ensure that each compensation capacitor and current-type light-emitting diode are in their respective initial states before refreshing, and will not be affected by the residual charge of the previous frame, so that the brightness of the current-type light-emitting diode will not be affected by the brightness of the previous frame, which is beneficial to improving the display contrast; the pixel compensation rate can reach 99.95%, the compensation efficiency is very good, and the stability of the display brightness of the current-type light-emitting diode is greatly improved.

[0120] Those skilled in the art will appreciate that all or part of the processes of the above-mentioned embodiments can be implemented by instructing related hardware through a computer program, and the program can be stored in a computer-readable storage medium, wherein the computer-readable storage medium is a disk, an optical disk, a read-only storage memory, or a random access memory, etc.

[0121] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. An 8T2C enhancement / depletion drive tube threshold voltage compensation circuit, characterized in that: include: A current-type light-emitting diode, a switch tube unit, a driving tube, and a compensation capacitor unit; wherein the switch tube unit includes first to seventh switch tubes; and the compensation capacitor unit includes a first compensation capacitor and a second compensation capacitor; The drain of the first switch tube is connected to the second reference voltage, and the source is connected to the gate of the driving tube; the drain of the second switch tube is connected to the power supply voltage, and the source is connected to the drain of the driving tube; the drain of the third switch tube is connected to the external input data, and the source is connected to the gate of the driving tube; the drain of the fourth switch tube is connected to the power supply voltage, and the source is connected to the drain of the driving tube; the source of the fifth switch tube is connected to the first reference voltage, and the drain is connected to the source of the driving tube; the source of the sixth switch tube is grounded, and the drain is connected to the anode of the current-type light-emitting diode; the drain of the seventh switch tube is connected to the source of the driving tube, and the source is connected to the anode of the current-type light-emitting diode; the cathode of the current-type light-emitting diode is grounded; One end of the first compensation capacitor is connected to the gate electrode of the driving tube, and the other end is connected to the source electrode of the driving tube; one end of the second compensation capacitor is connected to the source electrode of the driving tube, and the other end is connected to the power supply voltage.

2. The 8T2C enhancement / depletion mode driver threshold voltage compensation circuit according to claim 1, characterized in that: It also includes first to fourth clock signals input from the outside; wherein, The first clock signal controls the on and off of the fifth switch tube and the sixth switch tube; The second clock signal controls the on and off of the first switch tube and the fourth switch tube; The third clock signal controls the on and off of the third switch tube; The fourth clock signal controls the on and off of the second switch tube and the seventh switch tube.

3. The 8T2C enhancement / depletion mode driver threshold voltage compensation circuit according to claim 1, characterized in that: The difference between the second reference voltage and the driving tube threshold is greater than the first reference voltage.

4. The 8T2C enhancement / depletion mode driver threshold voltage compensation method according to claim 1, characterized in that: The power supply voltage is 15V DC voltage.

5. The 8T2C enhancement / depletion mode driver threshold voltage compensation method according to claim 1, characterized in that: The first to seventh switch tubes and the driving tube are all N-type.

6. A method for compensating the threshold voltage of an enhancement mode / depletion mode driver implemented by the circuit according to any one of claims 1 to 5, characterized in that: Including in order: Initialization phase, threshold voltage compensation phase, data input phase, light emitting phase; among them, The initialization stage is used to obtain the initial states of the first compensation capacitor and the second compensation capacitor based on the first reference voltage, and discharge the terminal charge of the current-type light-emitting diode; The threshold voltage compensation stage is used to measure and compensate the driver tube threshold voltage based on the second reference voltage and the power supply voltage; The data input stage is used to calculate the source voltage of the driving tube based on the external input data; The light emitting stage is used to obtain the driving current of the current-type light emitting diode based on the source voltage of the driving tube.

7. The 8T2C enhancement / depletion mode driver threshold voltage compensation method according to claim 6, characterized in that: The initialization phase includes: The first clock signal is at a high level, and the fifth and sixth switch tubes are turned on; the second to fourth clock signals are at a low level, and the first to fourth and seventh switch tubes are turned off; The upper end of the first compensation capacitor is suspended, and the lower end voltage is the first reference voltage; the upper end of the second compensation capacitor is the power supply voltage, and the lower end is the first reference voltage; the anode of the current-type light-emitting diode is grounded to discharge the terminal charge.

8. The 8T2C enhancement / depletion mode driver threshold voltage compensation method according to claim 6, characterized in that: The threshold voltage compensation stage includes: The second clock signal is at a high level, and the first and fourth switch tubes are turned on; the first, third, and fourth clock signals are at a low level, and the second, third, fifth to seventh switch tubes are turned off; The gate of the driving tube is connected to the second reference voltage, and the driving tube is turned on based on the voltage difference between the gate and the source of the driving tube; after the driving tube is turned on, the source of the driving tube is charged to the difference between the second reference voltage and the threshold voltage of the driving tube based on the power supply voltage, and the driving tube is turned off; the threshold voltage is measured and compensated by using the source follower structure.

9. The 8T2C enhancement / depletion mode driver threshold voltage compensation method according to claim 6, characterized in that: The data input stage includes: The third clock signal is at a high level, and the third switch tube is turned on; the first, second, and fourth clock signals are at a low level, and the first, second, fourth to seventh switch tubes are turned on; Connect the gate of the driver tube to the voltage corresponding to the external input data, and use the following formula to get the source voltage of the driver tube in the data input stage: In S3 =(V DATA -V ref2 )*C2 / (C1+C2)+V ref2 -V th_T8 Among them, V S3 Represents the source voltage of the driver tube during the data input phase, V DATA Indicates the voltage corresponding to the external input data, V ref2 Represents the second reference voltage, V th_T8 represents the threshold voltage of the driving tube, C1 represents the first compensation capacitor, and C2 represents the second compensation capacitor.

10. The 8T2C enhancement / depletion mode driver threshold voltage compensation method according to claim 6, characterized in that: The lighting stage includes: Only the fourth clock signal is at a high level, the second switch tube and the seventh switch tube are turned on; the first to third clock signals are at a low level, the first, third to sixth switch tubes are turned off; The power supply voltage is connected to the anode of the current-type light-emitting diode through the second switch tube, the drive tube, and the seventh switch tube in sequence; the source voltage of the drive tube in the light-emitting stage is obtained using the following formula: V S4 =VDD*(R T7 +R diode ) / (R T2 +R T8 +R T7 +R diode ) Among them, V S4 Indicates the source voltage of the driving tube during the light-emitting stage, VDD indicates the power supply voltage, R T2 Represents the internal resistance of the second switch tube, R T8 Represents the internal resistance of the driver tube, R T7 Represents the internal resistance of the seventh switch tube, R diode Indicates the internal resistance of a current-mode light-emitting diode; Based on the driving tube source voltage in the data input stage and the driving tube source voltage in the light-emitting stage, the driving tube gate voltage in the light-emitting stage is obtained, and the driving tube gate-source voltage difference in the light-emitting stage is obtained using the following formula: Where V gs_T8 Represents the gate-source voltage difference of the driver tube, V G4 Indicates the gate voltage of the driving tube during the light-emitting stage, V S4 Indicates the source voltage of the driving tube during the light-emitting stage, V DATA Indicates the voltage corresponding to the external input data, V th_T8 Indicates the threshold voltage of the driver tube; Based on the gate-source voltage difference of the driving tube and the threshold voltage of the driving tube during the light-emitting stage, the driving current of the current-type light-emitting diode is obtained using the following formula: Where, I represents the driving current of the current-mode light-emitting diode, μ represents the electron mobility of the driver tube, C ox represents the gate dielectric capacitance of the driving tube, W represents the channel width of the driving tube, and L represents the channel length of the driving tube; The light emitting diode is driven based on the driving current to emit light with corresponding brightness.

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