A μLED unit light-emitting circuit, light-emitting control method thereof and display device

Abstract

The present application relates to a μLED unit light-emitting circuit, a light-emitting control method and a display device thereof, which belongs to the field of semiconductor technology and solves the problem that the existing GOA circuit has limited driving speed and that multiple openings when the resolution is high result in a longer period of time that cannot be used for light emission. The circuit includes: a PWM signal generating circuit, a light-emitting control circuit and a μLED, wherein the PWM signal generating circuit receives a light-emitting control signal and a comparison reference signal and generates a PWM signal with different pulse widths, wherein the comparison reference signal is a ramp signal; the light-emitting control circuit includes a driving transistor, which is used to control the on-time of the driving transistor based on PWM signals with different pulse widths to provide a driving current; and a μLED, which is used to control the light-emitting time of the μLED based on the driving current, wherein the anode of the μLED is connected to the drain of the driving transistor and the cathode of the μLED is connected to the first power supply voltage. The combination of analog voltage driving and PWM driving modes is realized to meet the regulation of high grayscale.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a μLED unit light-emitting circuit, a light-emitting control method thereof, and a display device. Background Art

[0002] In recent years, due to the advantages of μLED over AMOLED (Active-matrix organic light emitting diode), such as smaller device size, faster response speed, higher luminous efficiency, stronger stability and longer service life, the display application field based on μLED has developed rapidly and attracted more and more attention. In this field, oxide thin film transistor (TFT) materials represented by low temperature polycrystalline silicon (LTPS) have become important materials for active μLED display due to their advantages such as high mobility and high stability. At present, there are two most critical issues to be solved for active μLED display technology:

[0003] 1. μLED mass transfer technology: In order to reduce costs and maximize the advantages of μLED, μLED mass transfer technology is critical.

[0004] 2. Design of μLED grayscale expansion. Since the IV characteristic curve of μLED is very steep, that is, the change of the voltage between the two electrodes corresponding to the low grayscale current to the high grayscale current of μLED is very small, such as Figure 1 As shown, the gray scale is difficult to develop through the traditional analog voltage driving method.

[0005] In the active μLED display circuit based on p-type LTPS TFT, most of the existing technologies use the traditional 2T1C pixel circuit with micro silicon-based CMOS driver to achieve high grayscale display (refer to Figure 2 ). In addition, digital pulse width modulation (PWM) driving has also received widespread attention. PWM driving is to control the brightness perceived by the human eye by controlling the time the μLED emits light. Under the conditions of the same drive current and the same refresh frequency, the greater the proportion of the μLED light emission time to the total refresh time, the higher the brightness perceived by the human eye. In this way, precise control of grayscale brightness can be achieved (refer to Figure 3 ).

[0006] The above-mentioned prior art has the following technical defects: the active μLED display technology based on micro silicon-based CMOS drive is relatively expensive, and the analog voltage drive method means that the IC needs an extremely fast and accurate circuit structure to meet the extremely high voltage resolution, and the circuit complexity is high. At the same time, the use of CMOS drive has an adverse effect on the flexibility, transparency, and thickness of the panel. With the PWM scheme, the drive control signal can be generated by the surface drive circuit (GOA). However, the drive signal is no longer a traditional line-by-line scanning signal, but a complex disordered signal to meet the grayscale distribution. The circuit design for generating the signal is complex, which increases the complexity of the panel. In addition, the PWM scheme divides each frame display time into n subframes of equal proportion. Each pixel unit needs to be turned on once in each subframe time. Each time the data voltage input by the IC determines whether the μLED corresponding to the subframe emits light. This method can achieve a higher grayscale, but the GOA circuit driving speed is limited. When the resolution is high, multiple turns on result in a longer part of the time being unable to be used for light emission, thereby limiting the increase in the number of grayscales. Summary of the invention

[0007] In view of the above analysis, the embodiments of the present application aim to provide a μLED unit light-emitting circuit, a light-emitting control method and a display device thereof, so as to solve the problem that the existing GOA circuit has limited driving speed. When the resolution is high, multiple activations result in a longer period of time that cannot be used for light emission, thereby limiting the improvement of the number of grayscale levels.

[0008] On the one hand, an embodiment of the present application provides a μLED unit light-emitting circuit, comprising: a PWM signal generating circuit, a light-emitting control circuit and a μLED, wherein the PWM signal generating circuit is used to receive a light-emitting control signal and a comparison reference signal and generate a PWM signal with different pulse widths based on the light-emitting control signal and the comparison reference signal, wherein the comparison reference signal is a ramp signal; the light-emitting control circuit comprises a driving transistor, which is used to receive the PWM signals with different pulse widths from the PWM signal generating circuit and control the on-time of the driving transistor based on the PWM signals with different pulse widths to provide a driving current; and the μLED, which is used to receive the driving current from the light-emitting control circuit and control the light-emitting time of the μLED based on the driving current, wherein the anode of the μLED is connected to the drain of the driving transistor and the cathode of the μLED is connected to a first power supply voltage.

[0009] The beneficial effects of the above technical solution are as follows: Through the circuit structure and working mode of the present application, the combination of analog voltage drive and PWM drive mode can be realized to meet the regulation of high grayscale. For 60Hz 2k resolution display applications, the modulatable luminous time of the present application can reach more than 84% of the entire refresh time, and 12bit grayscale can be achieved.

[0010] Based on further improvements of the above circuit, the PWM signal generating circuit includes a reset circuit, a compensation circuit and an inverter, wherein the reset circuit is used to receive a reset signal and initialize the μLED unit light-emitting circuit; the inverter is connected to the output end of the reset circuit and is used to control the conduction of the transistor in the inverter based on the comparison between the input terminal voltage of the inverter and the power supply input terminal voltage to generate a PWM signal with different pulse widths; and the compensation circuit is used to compensate for the input terminal voltage of the inverter and the power supply input terminal voltage.

[0011] Based on further improvement of the above circuit, the reset circuit includes a first transistor, wherein the gate of the first transistor receives the reset signal, the source of the first transistor is connected to a reference power supply voltage, and the drain of the first transistor is connected to an input end of the inverter, wherein the reference power supply voltage is greater than the first power supply voltage.

[0012] Based on the further improvement of the above circuit, the inverter includes a fourth transistor, a fifth transistor and a sixth transistor connected as an inverter, and the μLED unit light-emitting circuit also includes a first capacitor, wherein the gate of the fourth transistor receives the light-emitting control signal, the source of the fourth transistor is connected to the second power supply voltage, and the drain of the fourth transistor is the power supply input terminal and is connected to the source of the sixth transistor; the gate of the sixth transistor is the input terminal of the inverter and receives the comparison reference signal via the first capacitor, the drain of the sixth transistor is the output terminal of the inverter and is connected to the source of the fifth transistor; and the gate of the fifth transistor receives the light-emitting control signal, and the drain of the fifth transistor is connected to the reference power supply voltage, wherein the second power supply voltage is greater than the reference power supply voltage.

[0013] Based on further improvements of the above circuit, the compensation circuit includes a second transistor and a third transistor, wherein the gate of the second transistor is used to receive a row scan signal, the source of the second transistor is connected to the gate of the sixth transistor, and the drain of the second transistor is connected to the output end of the inverter; and the gate of the third transistor is used to receive the row scan signal, the source of the third transistor is connected to the drain of the fourth transistor and the source of the sixth transistor, and the drain of the third transistor receives a PWMD signal, wherein the PWMD signal is a voltage value that changes according to the luminous brightness of the μLED.

[0014] Based on further improvement of the above circuit, the light-emitting control circuit includes an edge improvement circuit and a driving circuit, wherein the edge correction circuit is used to receive the PWM signals of different pulse widths and the light-emitting control signal and correct the edge steepness of the PWM signals of different pulse widths; and the driving circuit is used to control the conduction time of the driving transistor based on the corrected PWM signals of different pulse widths to provide the driving current.

[0015] Based on further improvement of the above circuit, the edge correction circuit includes a seventh transistor, an eighth transistor and a second capacitor, wherein the gate of the seventh transistor is connected to the output end of the inverter and receives a third power supply voltage via the second capacitor, the source of the seventh transistor is connected to the drain of the eighth transistor, and the drain of the seventh transistor is connected to the drain of the ninth transistor; and the gate of the eighth transistor receives the light-emitting control signal, and the source of the eighth transistor receives the third power supply voltage.

[0016] Based on further improvements of the above circuit, the driving circuit includes the ninth transistor, the tenth transistor, the eleventh transistor and the third capacitor, the tenth transistor is the driving transistor, wherein the gate of the ninth transistor receives the row scanning signal, the source of the ninth transistor receives the PAMD signal, and the PAMD signal is the voltage value when the luminous brightness is the highest; the source of the tenth transistor is connected to the drain of the eleventh transistor, and the gate of the tenth transistor is connected to the drain of the seventh transistor and the drain of the ninth transistor; the gate of the eleventh transistor receives the light-emitting control signal, and the source of the eleventh transistor receives the third power supply voltage; and one end of the third capacitor is connected to the third power supply voltage, and the other end of the third capacitor is connected to the drain of the seventh transistor and the drain of the ninth transistor, wherein the third power supply voltage is less than or equal to the second power supply voltage and greater than the reference power supply voltage.

[0017] Based on further improvement of the above circuit, the first transistor to the eleventh transistor are P-type TFT transistors.

[0018] On the other hand, an embodiment of the present application provides a display device, comprising m×n μLED unit light-emitting circuits described in the above embodiments.

[0019] On the other hand, an embodiment of the present application provides a μLED light-emitting control method, including a comparative light-emitting step, wherein the comparative light-emitting step includes: generating PWM signals with different pulse widths based on a light-emitting control signal EM and a comparison reference signal SWEEP, wherein the comparison reference signal SWEEP is a linearly increasing ramp signal; receiving the PWM signals with different pulse widths and controlling the on-time of a driving transistor based on the PWM signals with different pulse widths to provide a driving current; and receiving the driving current from the light-emitting control circuit and controlling the light-emitting time of the μLED based on the driving current.

[0020] Based on the further improvement of the above method, the driving current is:

[0021]

[0022] Among them, the μ, C ox and represents the mobility, unit area gate dielectric capacitance and channel width-to-length ratio of the driving transistor respectively, PAMD is the voltage value when the luminous brightness is the highest, V LED is the voltage of the μLED, and V th10 is the threshold voltage of the driving transistor.

[0023] Based on a further improvement of the above method, before the comparison light-emitting step, it also includes an initialization step and a row scanning step. The initialization step initializes the μLED unit light-emitting circuit of the display device based on the reset signal RESET; and the row scanning step, after the initialization step, scans the μLED unit light-emitting circuit of the display device row by row based on the row scanning signal SN.

[0024] Based on a further improvement of the above method, the initialization step includes: providing the reset signal RESET to the gate of the first transistor T1, the first transistor T1 is turned on, so that the source of the first transistor T1 is connected to the reference power supply voltage REF to set the drain of the first transistor T1 to the reference power supply voltage REF, wherein the reset signal is a high level.

[0025] Based on a further improvement of the above method, the row scanning step includes: providing the row scanning signal SN to the gates of the second transistor T2 and the third transistor T3, the second transistor T2, the third transistor T3, and the sixth transistor T6 are turned on, so that the source of the sixth transistor T6 is connected to the PWMD signal via the third transistor T3 and is set to PWMD, and the drain of the sixth transistor T6 is connected to the gate of the sixth transistor T6 via the second transistor T2, so that the drain voltage of the sixth transistor T6 and the gate voltage of the sixth transistor T6 are PWMD-|V th6 |, wherein the PWMD signal is a voltage value that changes according to the luminous brightness of the μLED; providing a row scan signal SN to the gate of the ninth transistor T9, so that the ninth transistor T9 is turned on, so as to set the gate of the driving transistor to PAMD via the ninth transistor T9, wherein PAMD is a voltage value when the luminous brightness of the μLED is the highest, and the row scan signal SN is a high level.

[0026] Based on a further improvement of the above method, the comparison light emission step further includes: providing the light emission control signal EM to the gates of the fourth transistor T4 and the fifth transistor T5 and providing the comparison reference signal SWEEP to the gate of the sixth transistor T6 via a capacitor, turning on the fourth transistor T4, the fifth transistor T5 and the sixth transistor T6 and connecting them as an inverter, so that the source of the sixth transistor T6 is the power input terminal of the inverter and is connected to the first power supply voltage VGH via the fourth transistor T4, so that the voltage of the power input terminal of the inverter is the first power supply voltage VGH; the gate of the sixth transistor T6 is the input terminal of the inverter and the voltage of the power input terminal of the inverter is PWMD-|V th6 |+ΔSWEEP; the drain of the sixth transistor T6 is the output end of the inverter and is connected to the reference power supply voltage REF via the fifth transistor T5, so that the voltage at the output end of the inverter is at a high level and the seventh transistor T7 remains cut off, wherein the size of the sixth transistor T6 is larger than the size of the fifth transistor T5, and the light emitting control signal EM is a pulse signal.

[0027] Based on further improvement of the above method, the comparative light emission step further includes: turning on the driving transistor T10 so that the gate voltage of the driving transistor T10 maintains the PAMD signal, and the source of the driving transistor T10 is connected to the second power supply voltage VDD to provide the driving current so that the μLED starts to emit light.

[0028] Based on further improvements of the above method, the comparative light-emitting step further includes: providing the light-emitting control signal EM to the gates of the eighth transistor T8 and the eleventh transistor T11, the eighth transistor T8, the driving transistor T10 and the eleventh transistor T11 are turned on, so that the gate voltage of the driving transistor T10 maintains the PAMD signal, and the source of the driving transistor T10 is connected to the second power supply voltage VDD via the turned-on eleventh transistor T11 to provide the driving current, so that the μLED starts to emit light.

[0029] Based on the further improvement of the above method, the comparison light-emitting step further comprises: when the comparison reference signal SWEEP is linearly increased so that the voltage PWMD-|V th6 |+ΔSWEEP is greater than VGH-|V th6 |, the sixth transistor T6 is turned off to reduce the voltage at the output end of the inverter to REF, so that the seventh transistor T7 is turned on to transmit the second power supply voltage VDD to the gate of the driving transistor T10 or set the gate of the driving transistor T10 to the second power supply voltage VDD, and the driving transistor T10 is turned off so that the μLED stops emitting light.

[0030] Based on a further improvement of the above method, the light-emitting control signal EM1 is provided to the gate of the eleventh transistor T11 and the light-emitting control signal EM2 is provided to the eighth transistor T8, the eighth transistor T8, the driving transistor T10 and the eleventh transistor T11 are turned on, so that the gate voltage of the driving transistor T10 maintains the PAMD signal, and the source of the driving transistor T10 is connected to the second power supply voltage VDD via the turned-on eleventh transistor T11 to provide the driving current, so that the μLED starts to emit light, wherein the light-emitting control signal EM2 and the light-emitting control signal EM1 are pulse signals, and the falling edge of the light-emitting control signal EM2 lags behind the falling edge of the light-emitting control signal EM1.

[0031] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0032] 1. Through the circuit structure and working mode of this application, the combination of traditional analog voltage drive and PWM drive mode can be realized to meet the regulation of high grayscale. For 60Hz 2k resolution display applications, the luminous time that can be modulated by this application can reach more than 84% of the entire refresh time, and 12bit grayscale can be achieved.

[0033] 2. In the row scanning stage, the connection of T3, T2 and T6 forms a diode connection structure. thIn the compensation phase, the source voltage of T6 is fixed, and the gate is discharged through T6, so that the threshold voltage of T6 can be detected, ensuring that the comparison light-emitting phase is independent of the threshold voltage of T6. This avoids the positive bias stress (e.g., PBS, Positive bias stress) caused by the positive bias voltage on the threshold voltage of T6, which causes the comparison result to drift.

[0034] 3. In the comparative luminescence stage, T4, T5 and T6 are connected as an inverter. By comparing the voltage between the input terminal of the inverter (point A) and the power input terminal (point D), PWM signals with different pulse widths can be generated at the output terminal of the inverter (point B).

[0035] 4. By controlling the size of the PWMD analog voltage value, the opening time of T6 can be controlled. The opening time of T6 can control the level of point B, thereby controlling the start time of T7, and then controlling the opening time of T10, and finally realizing the control of the light-emitting time of μLED and realizing PWM control of light-emitting brightness.

[0036] In the present application, 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 application will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present application. The purpose and other advantages of the present application can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings are only for the purpose of illustrating specific embodiments and are not to be considered as limiting the present application. The same reference symbols denote the same components throughout the accompanying drawings.

[0038] Figure 1 The μLED current-voltage transfer curve obtained for the traditional analog voltage driving circuit.

[0039] Figure 2 It is an active μLED display for existing micro silicon-based CMOS.

[0040] Figure 3 It is a PWM driving solution for existing μLED high grayscale display.

[0041] Figure 4 1 is a circuit structure diagram and a timing diagram of a μLED unit light-emitting circuit according to an embodiment of the present application.

[0042] Figure 5 4 is a circuit structure diagram of the initialization stage of the μLED unit light-emitting circuit according to an embodiment of the present application.

[0043] Figure 64 is a circuit structure diagram of the row scanning stage (also called the data input compensation stage) of the μLED unit lighting circuit according to an embodiment of the present application.

[0044] Figure 7 is a circuit structure diagram of a comparative light-emitting stage of a μLED unit light-emitting circuit according to an embodiment of the present application.

[0045] Figure 8 1 is a timing diagram of different light-emitting control signals of the μLED unit light-emitting circuit according to an embodiment of the present application.

[0046] Fig. 9 1 is a PAM and PWM step-by-step input circuit diagram and timing diagram of a μLED unit lighting circuit according to an embodiment of the present application. DETAILED DESCRIPTION

[0047] The preferred embodiments of the present application are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the present application and are used together with the embodiments of the present application to illustrate the principles of the present application, and are not used to limit the scope of the present application.

[0048] A specific embodiment of the present application discloses a μLED unit lighting circuit, including: a PWM signal generating circuit 402, a lighting control circuit 404 and a μLED. Figure 4 , the μLED unit light-emitting circuit will be described in detail.

[0049] refer to Figure 4, the PWM signal generating circuit 402 is used to receive the light-emitting control signal EMEM and the comparison reference signal SWEEP and generate PWM signals with different pulse widths based on the light-emitting control signal EM and the comparison reference signal SWEEP, wherein the comparison reference signal SWEEP is a ramp signal. The PWM signal generating circuit 402 includes a reset circuit, a compensation circuit and an inverter. In an embodiment, the reset circuit is used to receive a reset signal RESET and initialize the μLED unit light-emitting circuit. In an embodiment, the reset circuit includes a first transistor T1, wherein the gate of the first transistor T1 receives the reset signal RESET, the source of the first transistor T1 is connected to the reference power supply voltage REF, and the drain of the first transistor T1 is connected to the input terminal (point A) of the inverter, wherein the reference power supply voltage REF is greater than the first power supply voltage VGL. The inverter is connected to the output terminal of the reset circuit and is used to compare the input terminal voltage of the inverter (i.e., the voltage at point A) with the voltage at the power supply input terminal (i.e., the voltage at point D) to control the conduction of the transistor T6 in the inverter to generate PWM signals with different pulse widths. In an embodiment, the inverter includes a fourth transistor T4, a fifth transistor T5 and a sixth transistor T6 connected as an inverter, and the μLED unit light-emitting circuit further includes a first capacitor C1, wherein the gate of the fourth transistor T4 receives a light-emitting control signal EM, the source of the fourth transistor T4 is connected to the second power supply voltage VGH, and the drain of the fourth transistor T4 is the power supply input terminal (point D) and is connected to the source of the sixth transistor T6; the gate of the sixth transistor T6 is the input terminal of the inverter (i.e., point A) and receives the comparison reference signal SWEEP via the first capacitor C1, the drain of the sixth transistor T6 is the output terminal of the inverter (i.e., point B) and is connected to the source of the fifth transistor T5; and the gate of the fifth transistor T5 receives the light-emitting control signal EM, and the drain of the fifth transistor T5 is connected to the reference power supply voltage REF, wherein the second power supply voltage VGH is greater than the reference power supply voltage REF. The compensation circuit is used to compensate the input terminal voltage of the inverter (i.e., point A voltage) and the power supply input terminal voltage (i.e., point D voltage). The compensation circuit includes a second transistor T2 and a third transistor T3, wherein the gate of the second transistor T2 is used to receive a row scan signal SN, the source of the second transistor T2 is connected to the gate of the sixth transistor T6, and the drain of the second transistor T2 is connected to the output end (i.e., point B) of the inverter; and the gate of the third transistor T3 is used to receive the row scan signal SN, the source of the third transistor T3 is connected to the drain of the fourth transistor T4 and the source of the sixth transistor T6, and the drain of the third transistor T3 receives a PWMD signal, wherein the PWMD signal is a voltage value that changes according to the light emitting brightness of the μLED. The first transistor T1 to the sixth transistor T6 are P-type TFT transistors.

[0050] refer to Figure 4The light emitting control circuit 404 includes a driving transistor, which is used to receive PWM signals of different pulse widths from the PWM signal generating circuit 402 and control the on-time of the driving transistor based on the PWM signals of different pulse widths to provide a driving current. The light emitting control circuit 404 includes an edge improvement circuit and a driving circuit. The edge correction circuit is used to receive PWM signals of different pulse widths and the light emitting control signal EM and correct the edge steepness of the PWM signals of different pulse widths to improve or increase the edge steepness of the PWM signals, so as to accurately control the driving transistor, for example, to turn on or off. In an embodiment, the edge correction circuit includes a seventh transistor T7 and an eighth transistor T8, and the μLED unit light emitting circuit further includes a second capacitor C2, wherein the gate of the seventh transistor T7 is connected to the output terminal of the inverter (i.e., point B) and receives the third power supply voltage VDD via the second capacitor C2, the source of the seventh transistor T7 is connected to the drain of the eighth transistor T8, and the drain of the seventh transistor T7 is connected to the drain of the ninth transistor T9 (i.e., point C); and the gate of the eighth transistor T8 receives the light emitting control signal EM, and the source of the eighth transistor T8 receives the third power supply voltage VDD. A driving circuit is used to control the on-time of the driving transistor T10 based on the corrected PWM signal of different pulse widths to provide a driving current. The driving circuit includes a ninth transistor T9, a tenth transistor T10 and an eleventh transistor T11, and the driving circuit also includes a third capacitor, the tenth transistor T10 is a driving transistor, wherein the gate of the ninth transistor T9 receives a row scanning signal SN, the source of the ninth transistor T9 receives a PAMD signal, and the PAMD signal is a voltage value when the light emitting brightness is the highest; the source of the tenth transistor T10 is connected to the drain of the eleventh transistor T11, the gate of the tenth transistor T10 is connected to the drain of the seventh transistor T7 and the drain of the ninth transistor T9; the gate of the eleventh transistor T11 receives a light emitting control signal EM, and the source of the eleventh transistor T11 receives a third power supply voltage; and one end of the third capacitor C3 is connected to the third power supply voltage VDD, and the other end of the third capacitor is connected to the drain of the seventh transistor T7 and the drain of the ninth transistor T9 (i.e., point C), wherein the third power supply voltage VDD is less than or equal to the second power supply voltage VGH and greater than the reference power supply voltage REF. The seventh transistor T7 to the eleventh transistor T11 are P-type TFT transistors.

[0051] refer to Figure 4 , μLED, for receiving a driving current from the light emitting control circuit 404 and controlling the light emitting time of the μLED based on the driving current, wherein the anode of the μLED is connected to the drain of the driving transistor and the cathode of the μLED is connected to the first power supply voltage VGL.

[0052] Compared with the prior art, in the μLED unit light-emitting circuit provided in this embodiment, through the circuit structure and working mode of this application, the combination of traditional analog voltage drive and PWM drive mode can be realized to meet the regulation of high grayscale. For 60Hz 2k resolution display applications, the light-emitting time that can be modulated by this application can reach more than 84% of the entire refresh time, and 12-bit grayscale can be achieved.

[0053] Another specific embodiment of the present application discloses a display device, including m×n μLED unit light-emitting circuits described in the above embodiments.

[0054] Another specific embodiment of the present application discloses a μLED light emission control method, including an initialization step, a row scanning step, and a comparison light emission step. Figures 4 to 9 , each step of the μLED light emitting control method is described in detail.

[0055] refer to Figure 4 and Figure 5 , the initialization step, that is Figure 4 In the time period (1) in the timing diagram of , the μLED unit light emitting circuit of the display device is initialized based on the reset signal RESET. The initialization step includes: providing the reset signal RESET to the gate of the first transistor T1, turning on the first transistor T1, so that the source of the first transistor T1 is connected to the reference power supply voltage REF to set the drain of the first transistor T1 to the reference power supply voltage REF, wherein the reset signal RESET is at a high level.

[0056] refer to Figure 4 and Figure 6 , the row scanning step (also called the data input compensation step) is, Figure 4 (2) in the timing diagram of , after the initialization step, the μLED unit light-emitting circuit of the display device is scanned line by line based on the row scanning signal SN. The row scanning step includes: providing the row scanning signal SN to the gates of the second transistor T2 and the third transistor T3, and the second transistor T2, the third transistor T3, and the sixth transistor T6 are turned on, so that the source of the sixth transistor T6 (i.e., point D) is connected to the PWMD signal via the turned-on third transistor T3 and is set to PWMD, and the drain of the sixth transistor T6 (i.e., point B) is connected to the gate of the sixth transistor T6 (i.e., point A) via the second transistor T2, so that the drain voltage of the sixth transistor T6 and the gate voltage of the sixth transistor T6 are PWMD-|V th6|, wherein the PWMD signal is a voltage value that changes according to the luminous brightness of the μLED; the row scan signal SN is provided to the gate of the ninth transistor T9, so that the ninth transistor T9 is turned on, so as to set the gate of the driving transistor to PAMD via the ninth transistor T9, wherein PAMD is the voltage value when the luminous brightness of the μLED is the highest, and the row scan signal SN is at a high level.

[0057] refer to Figure 4 and Figure 7 , compare the luminescence step, i.e., Figure 4 (3) in the timing diagram includes: generating PWM signals with different pulse widths based on the light-emitting control signal EM and the comparison reference signal SWEEP, wherein the comparison reference signal SWEEP is a linearly increasing ramp signal; receiving PWM signals with different pulse widths and controlling the on-time of the driving transistor based on the PWM signals with different pulse widths to provide a driving current; and receiving the driving current from the light-emitting control circuit and controlling the light-emitting time of the μLED based on the driving current. The driving current is:

[0058]

[0059] Among them, μ, C ox and They represent the mobility of the driving transistor, the gate dielectric capacitance per unit area, and the channel width-to-length ratio, respectively. PAMD is the voltage value when the luminous brightness is the highest. V LED is the voltage of the μLED, and V th10 is the threshold voltage of the driving transistor.

[0060] refer to Figure 7 The comparison light-emitting step includes: providing the light-emitting control signal EM to the gates of the fourth transistor T4 and the fifth transistor T5 and providing the comparison reference signal SWEEP to the gate of the sixth transistor T6 (i.e., point A) via the capacitor, turning on the fourth transistor T4, the fifth transistor T5 and the sixth transistor T6 and connecting them as an inverter, so that the source of the sixth transistor T6 is the power input terminal of the inverter (i.e., point D) and is connected to the first power supply voltage VGH via the fourth transistor T4, so that the voltage of the power input terminal of the inverter is the first power supply voltage VGH; the gate of the sixth transistor T6 is the input terminal of the inverter and the voltage of the power input terminal of the inverter is PWMD-|V th6 |+ΔSWEEP; The drain of the sixth transistor T6 is the output terminal of the inverter and is connected to the reference power supply voltage REF via the fifth transistor T5, so that the voltage of the output terminal of the inverter is high level and the seventh transistor T7 remains cut off, wherein the size of the sixth transistor T6 is larger than the size of the fifth transistor T5, and the light emitting control signal EM is a pulse signal. Reference Figure 7, the comparative light-emitting step further includes: providing the light-emitting control signal EM to the gates of the eighth transistor T8 and the eleventh transistor T11, the eighth transistor T8, the driving transistor T10 and the eleventh transistor T11 are turned on, so that the gate voltage of the driving transistor T10 (i.e., point C) maintains the PAMD signal, and the source of the driving transistor T10 is connected to the second power supply voltage VDD via the turned-on eleventh transistor T11 to provide a driving current, so that the μLED starts to emit light. Optionally, the eleventh transistor T11 is removed. The comparative light-emitting step further includes: the driving transistor T10 is turned on, so that the gate voltage of the driving transistor T10 maintains the PAMD signal, and the source of the driving transistor T10 is connected to the second power supply voltage VDD to provide a driving current, so that the μLED starts to emit light.

[0061] refer to Figure 7 The comparison light-emitting step further includes: when the comparison reference signal SWEEP is linearly increased so that the voltage PWMD-|V th6 |+ΔSWEEP is greater than VGH-|V th6 |, the sixth transistor T6 is turned off to reduce the voltage at the output end of the inverter to REF, so that the seventh transistor T7 is turned on to transmit the second power supply voltage VDD to the gate of the driving transistor T10 or set the gate of the driving transistor T10 to the second power supply voltage VDD, and the driving transistor T10 is turned off so that the μLED stops emitting light.

[0062] refer to Figure 8 , the light-emitting control signal EM1 is provided to the gate of the eleventh transistor T11 and the light-emitting control signal EM2 is provided to the eighth transistor T8, the eighth transistor T8, the driving transistor T10 and the eleventh transistor T11 are turned on, so that the gate voltage of the driving transistor T10 maintains the PAMD signal, and the source of the driving transistor T10 is connected to the second power supply voltage VDD via the turned-on eleventh transistor T11 to provide a driving current, so that the μLED starts to emit light, wherein the light-emitting control signal EM2 and the light-emitting control signal EM1 are pulse signals, and the falling edge of the light-emitting control signal EM2 lags behind the falling edge of the light-emitting control signal EM1.

[0063] refer to Figure 4 The display device includes a plurality of rows of μLED unit light emitting circuits. Figure 4 and Figure 5 , the initialization step (1) in the timing diagram simultaneously initializes the light-emitting circuits of multiple rows of μLED units. Figure 4 and Figure 6, the row scanning step (2) in the timing diagram includes scanning the display device row by row, for example, the row scanning signal SN is provided to the first row to scan the first row, the row scanning signal SN+1 is provided to the second row to scan the second row, etc. The row scanning step includes performing row scanning (2), for example, the row scanning signal. Figure 4 and Figure 7 The comparison light-emitting step (3) in the timing diagram controls the light-emitting of the display device.

[0064] Fig. 9 The initialization step (1) is the same as Figure 4 and Figure 5 The initialization step (1) in is exactly the same. Fig. 9 Comparison of luminescence step (4) with Figure 4 and Figure 7 The comparative luminescence step (3) in is exactly the same. Fig. 9 The row scanning steps for each row of μLED unit lighting circuit include Fig. 9 The PWAD input stage (2) in the figure sets point D to PWAD and the PAMD input stage (3) sets point C to PAMD. In addition, the time delay of SN relative to SNN is related to the number of scan lines, and the specific time is SN scan pulse width * number of scan lines. The time delay of SN+1 relative to SNN+1 is the same as the time delay of SN relative to SNN. Compared with Figure 4 The timing diagram in Fig. 9 The timing diagram in sets point C to PAMD through additional row scanning signals SNN, SNN+1, etc. For example, SN and SNN are used for row scanning of the first row of μLED unit light emitting circuits, SN+1 and SNN+1 are used for row scanning of the first row of μLED unit light emitting circuits, and so on.

[0065] In the following, reference will be made to Figures 4 to 9 , the μLED unit light-emitting circuit and the μLED light-emitting control method are described in detail by way of specific examples.

[0066] The present application provides an active μLED display pixel circuit that meets high grayscale requirements. The circuit adopts an inverter / comparator structure to convert analog voltage into digital pulse width inside the pixel. The IC is compatible with the traditional analog voltage drive circuit design, has low complexity, and greatly reduces costs. The scanning signal can be realized through the GOA circuit, which only needs to be turned on once per frame time, and as much time as possible is used for light control. Compared with the prior art, the performance of the active μLED display circuit is further improved, and high grayscale display is further realized.

[0067] refer to Figure 4, the μLED unit lighting circuit consists of three capacitors (C1, C2, and C3) and eleven TFTs, where T10 is the driving TFT that controls the lighting brightness of the μLED. The control signals are the reset signal RESET, the row scan signal SN, the lighting control signal EM, and the comparison reference signal SWEEP. Among them, the EM and SWEEP signals are global signals, and the RESET and SN are reusable signals, that is, the current-stage SN signal can serve as the next-stage RESET signal. The high level of the control signal is VGH, and the low level is VGL. In addition, a power supply VDD (VGH > VDD > REF), a reference voltage REF (VGL < REF < PWMD), data signals PAMD and PWMD are required. T4, T5, and T6 constitute an inverter / comparator structure to achieve the conversion of analog voltage to digital pulse width. The working mode can be divided into three stages:

[0068] Initialization stage

[0069] Reference Figure 5 , RESET is at a low level to turn on T1; SN is at a high level to turn off T2, T3, and T9; EM is at a high level to turn off T4, T5, T8, and T11 to prevent the μLED from flashing; the SWEEP signal remains at a low level unchanged, and the circuit state is as Figure 5 . The voltage at point A (VA) is set to REF.

[0070] Row scan stage (data input compensation stage)

[0071] Reference Figure 6 , RESET changes to a high level to turn off T1; SN changes to a low level to turn on T2, T3, and T9, the voltage at point D (VD) is set to PWMD, T2 and T6 form a diode connection, VA is charged until T6 turns off, and finally VA and the voltage at point B (VB) stabilize at PWMD - |V th6 |; T9 is turned on, and the voltage at point C (VC) is set to PAMD. EM maintains a high level to turn off T4, T5, T8, and T11 to prevent the μLED from flashing; the SWEEP signal remains at a low level unchanged, as Figure 6 . The compensation process in this stage can ensure that the drift of the threshold voltage of T6 will not affect the switching state of T6 in the subsequent comparison and lighting stage.

[0072] Comparison and lighting stage

[0073] Reference Figure 7 , RESET changes to a high level to turn off T1; SN is at a high level to turn off T2, T3, and T9; EM changes to a low level to turn on T4, T5, T8, and T11, as Figure 7 . Due to the effect of the storage capacitor C3, VC always remains PAMD, and the magnitude of PAMD controls the driving current of T10, that is, controls the brightness of the μLED. According to the transistor saturation current formula:

[0074]

[0075] Available in this stage I OLED The magnitude of the current is:

[0076]

[0077] Among them, μ, C ox and They represent the mobility of T10, the gate dielectric capacitance per unit area, and the channel width-to-length ratio. The SWEEP signal starts to change linearly from low to high. Through the capacitance coupling effect of C1, VA gradually increases linearly (VA = PWMD - |V th |+ΔSWEEP). T6 source voltage is VGH (VGH>PWMD-|V th |), the inverter / comparator structure works. At the beginning of the comparison light-emitting stage, VA is less than VGH, T6 is turned on, and since T6 is larger than T5, VB is high, T7 remains off, and the μLED current remains the above value. As the SWEEP signal becomes larger, VA gradually becomes larger than VGH-|V th |, that is, PWMD+ΔSWEEP>VGH, T6 is turned off, B gradually drops to REF, thereby turning on T7, transferring VDD to point C, turning off T10, and the μLED stops emitting light. The above comparison node has nothing to do with the T6 threshold voltage, but is only related to the PWMD size and SWEEP slope.

[0078] Through the above working process, it can be known that by controlling the size of the PWMD analog voltage value, the time when T6 is turned on can be controlled. The level of point B can be controlled during the T6 turn-on time, thereby controlling the start time of T7, and then controlling the turn-on time of T10, and finally realizing the control of the light-emitting time of the μLED, and achieving the purpose of PWM control of the light-emitting brightness. For example, the larger the PWMD, the shorter the T6 turn-on time, the shorter the time when point B maintains a high level, the longer the T7 turn-on time, the shorter the T10 turn-on time, and the shorter the light-emitting time. Therefore, the pixel circuit successfully uses the inverter / comparator structure to combine traditional analog drive with PWM drive to achieve grayscale expansion.

[0079] In addition, the above definitions of the various elements and methods are not limited to the various specific structures, shapes or methods mentioned in the embodiments.

[0080] 1. One end of C2 is connected to B, and the other end can be connected to VDD or any other DC power supply; one end of C3 is connected to C, and the other end can be connected to VDD or any other DC power supply.

[0081] 2. The rising edge of the T5 gate signal EM may affect the voltage increase at point B due to parasitic effects, thus causing T7 to be turned on incorrectly. In order to avoid the influence of point C, the above circuit uses T8 for protection. If the parasitic capacitance of the transistor is small and the panel parasitic effect is not obvious, T8 can be removed and the source of T7 can be directly connected to VDD.

[0082] 3. The rising edge of the T5 gate signal EM may affect the voltage at point B due to parasitic effects, thus causing T7 to turn on incorrectly, so T8 is needed for protection. The gate of T8 can directly use the EM signal, or use the EM2 signal with a longer high-level pulse width than the EM signal, to completely avoid the voltage change at point B under the influence of the EM rising edge from affecting point C, and achieve better protection effect. The relationship between the two signals is as follows: Figure 8 shown.

[0083] 4. PAMD and PWMD can be input simultaneously through two data signal lines according to the above working process, or they can be input successively through one data signal line (DATA). The corresponding circuit diagram and timing diagram for sequential input are as follows: Fig. 9 shown.

[0084] 5. T11 can be removed, the source of T10 is directly connected to VDD, and the cathode of μLED can be changed to EM control accordingly.

[0085] 6. The RESET signal that controls initialization can also be used as a global signal to control all pixels to be initialized at the same time and then perform data input compensation row by row.

[0086] 7. This application is also applicable to other p-type TFT devices.

[0087] In addition, since the manufacturing process of P-type TFT transistors requires a crystallization step, and the manufacturing equipment cost of the crystallization process is high, the cost of P-type TFT transistors is high. Therefore, P-type TFT transistors are suitable for outdoor large screens.

[0088] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0089] 1. Through the circuit structure and working mode of this application, the combination of analog voltage drive (such as PAM, Pulse amplitude modulation, known as pulse amplitude modulation) and PWM drive mode can be realized to meet the regulation of high grayscale. For 60Hz 2k resolution display applications, the modulatable luminous time of this application can reach more than 84% of the entire refresh time, and 12-bit grayscale can be achieved.

[0090] 2. In the row scanning stage, the connection of T3, T2 and T6 forms a diode connection structure. thIn the compensation phase, the source voltage of T6 is fixed, and the gate is discharged through T6, so that the threshold voltage of T6 can be detected, ensuring that the comparison light-emitting phase is independent of the threshold voltage of T6. This avoids the positive bias stress (e.g., PBS, Positive bias stress) caused by the positive bias voltage on the threshold voltage of T6, which causes the comparison result to drift.

[0091] 3. In the comparative luminescence stage, T4, T5 and T6 are connected as an inverter. By comparing the voltage between the input terminal of the inverter (point A) and the power input terminal (point D), PWM signals with different pulse widths can be generated at the output terminal of the inverter (point B).

[0092] 4. By controlling the size of the PWMD analog voltage value, the opening time of T6 can be controlled. The opening time of T6 can control the level of point B, thereby controlling the start time of T7, and then controlling the opening time of T10, and finally realizing the control of the light-emitting time of μLED and realizing PWM control of light-emitting brightness.

[0093] 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.

[0094] The above is only a preferred specific implementation of the present application, but the protection scope of the present application 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 in the present application should be covered within the protection scope of the present application.

Claims

1. A μLED unit lighting circuit, characterized in that: include: PWM signal generating circuit, light emitting control circuit and μLED, wherein: The PWM signal generating circuit is used to receive a light-emitting control signal and a comparison reference signal and generate PWM signals with different pulse widths based on the light-emitting control signal and the comparison reference signal, wherein the comparison reference signal is a ramp signal; The light emitting control circuit includes a driving transistor for receiving the PWM signals of different pulse widths from the PWM signal generating circuit and controlling the on-time of the driving transistor based on the PWM signals of different pulse widths to provide a driving current; and The μLED is configured to receive the driving current from the light emitting control circuit and control the light emitting time of the μLED based on the driving current, wherein the anode of the μLED is connected to the drain of the driving transistor and the cathode of the μLED is connected to a first power supply voltage, The light emitting control circuit comprises an edge correction circuit and a driving circuit, wherein the edge correction circuit is used to receive the PWM signals with different pulse widths and the light emitting control signal and correct the edge steepness of the PWM signals with different pulse widths; and the driving circuit is used to control the on-time of the driving transistor based on the corrected PWM signals with different pulse widths to provide the driving current; The edge correction circuit includes a seventh transistor, an eighth transistor and a second capacitor, wherein the gate of the seventh transistor is connected to the output end of the inverter in the PWM signal generating circuit and receives a third power supply voltage via the second capacitor, the source of the seventh transistor is connected to the drain of the eighth transistor, and the drain of the seventh transistor is connected to the drain of the ninth transistor; and the gate of the eighth transistor receives the light emitting control signal, and the source of the eighth transistor receives the third power supply voltage.

2. The μLED unit lighting circuit according to claim 1, characterized in that: The PWM signal generating circuit comprises a reset circuit, a compensation circuit and an inverter, wherein: The reset circuit is used to receive a reset signal and initialize the μLED unit light emitting circuit; The inverter is connected to the output terminal of the reset circuit and is used to control the conduction of the transistor in the inverter based on the comparison between the input terminal voltage of the inverter and the power input terminal voltage to generate PWM signals with different pulse widths; and The compensation circuit is used to compensate the input terminal voltage of the inverter and the power input terminal voltage.

3. The μLED unit lighting circuit according to claim 2, characterized in that: The reset circuit comprises a first transistor, wherein The gate of the first transistor receives the reset signal, the source of the first transistor is connected to a reference power supply voltage, and the drain of the first transistor is connected to an input terminal of the inverter, wherein the reference power supply voltage is greater than the first power supply voltage.

4. The μLED unit lighting circuit according to claim 3, characterized in that: The inverter includes a fourth transistor, a fifth transistor and a sixth transistor connected as an inverter, and the μLED unit light emitting circuit also includes a first capacitor, wherein, The gate of the fourth transistor receives the light emitting control signal, the source of the fourth transistor is connected to the second power supply voltage, and the drain of the fourth transistor is the power supply input terminal and connected to the source of the sixth transistor; The gate of the sixth transistor is the input terminal of the inverter and receives the comparison reference signal via the first capacitor, and the drain of the sixth transistor is the output terminal of the inverter and connected to the source of the fifth transistor; and The gate of the fifth transistor receives the light emitting control signal, and the drain of the fifth transistor is connected to the reference power supply voltage, wherein the second power supply voltage is greater than the reference power supply voltage.

5. The μLED unit lighting circuit according to claim 4, characterized in that: The compensation circuit includes a second transistor and a third transistor, wherein: The gate of the second transistor is used to receive a row scanning signal, the source of the second transistor is connected to the gate of the sixth transistor, and the drain of the second transistor is connected to the output end of the inverter; and The gate of the third transistor is used to receive the row scan signal, the source of the third transistor is connected to the drain of the fourth transistor and the source of the sixth transistor, and the drain of the third transistor receives a PWMD signal, wherein the PWMD signal is a voltage value that changes according to the luminous brightness of the μLED.

6. The μLED unit lighting circuit according to claim 5, characterized in that: The driving circuit includes the ninth transistor, the tenth transistor, the eleventh transistor and a third capacitor, the tenth transistor is the driving transistor, wherein: The gate of the ninth transistor receives the row scanning signal, and the source of the ninth transistor receives the PAMD signal, where the PAMD signal is a voltage value when the light emitting brightness is the highest; The source of the tenth transistor is connected to the drain of the eleventh transistor, and the gate of the tenth transistor is connected to the drain of the seventh transistor and the drain of the ninth transistor; The gate of the eleventh transistor receives the light emitting control signal, and the source of the eleventh transistor receives the third power supply voltage; and One end of the third capacitor is connected to the third power supply voltage, and the other end of the third capacitor is connected to the drain of the seventh transistor and the drain of the ninth transistor, wherein the third power supply voltage is less than or equal to the second power supply voltage and greater than the reference power supply voltage.

7. The μLED unit lighting circuit according to claim 6, characterized in that: The first transistor to the eleventh transistor are P-type TFT transistors.

8. A display device, characterized in that: The device comprises m×n μLED unit lighting circuits according to any one of claims 1 to 7.

9. A μLED light emission control method, characterized in that: The μLED light emission control method performed by the μLED unit light emission circuit according to any one of claims 1 to 7 includes a comparative light emission step, wherein the comparative light emission step includes: generating PWM signals with different pulse widths based on the light emitting control signal EM and a comparison reference signal SWEEP, wherein the comparison reference signal SWEEP is a linearly increasing ramp signal; receiving the PWM signals of different pulse widths and controlling the on-time of the driving transistor T10 based on the PWM signals of different pulse widths to provide a driving current; and The driving current is received from a light emission control circuit and a light emission time of the μLED is controlled based on the driving current.

10. The μLED light emission control method according to claim 9, characterized in that: The driving current is: Among them, the μ, C ox and represents the mobility, unit area gate dielectric capacitance and channel width-to-length ratio of the driving transistor respectively, PAMD is the voltage value when the luminous brightness is the highest, V LED is the voltage of the μLED, and V th10 is the threshold voltage of the driving transistor.

11. The μLED light emission control method according to claim 9, characterized in that: Before the comparative light emitting step, an initialization step and a row scanning step are also included. The initialization step initializes the μLED unit lighting circuit of the display device based on a reset signal RESET; and The row scanning step, after the initialization step, scans the μLED unit light emitting circuit of the display device row by row based on the row scanning signal SN.

12. The μLED light emission control method according to claim 11, characterized in that: The initialization step includes: The reset signal RESET is provided to the gate of the first transistor T1, the first transistor T1 is turned on, so that the source of the first transistor T1 is connected to the reference power supply voltage REF to set the drain of the first transistor T1 to the reference power supply voltage REF, wherein the reset signal is a high level.

13. The μLED light emission control method according to claim 12, characterized in that: The row scanning step comprises: The row scanning signal SN is provided to the gates of the second transistor T2 and the third transistor T3, and the second transistor T2, the third transistor T3, and the sixth transistor T6 are turned on, so that the source of the sixth transistor T6 is connected to the PWMD signal via the turned-on third transistor T3 and is set to PWMD, and the drain of the sixth transistor T6 is connected to the gate of the sixth transistor T6 via the second transistor T2, so that the drain voltage of the sixth transistor T6 and the gate voltage of the sixth transistor T6 are PWMD-|V th6 |, wherein the PWMD signal is a voltage value that changes according to the light luminance of the μLED; The row scan signal SN is provided to the gate of the ninth transistor T9, so that the ninth transistor T9 is turned on, so as to set the gate of the driving transistor to PAMD through the ninth transistor T9, wherein PAMD is the voltage value when the light brightness of the μLED is the highest, and the row scan signal SN is at a high level.

14. The μLED light emission control method according to claim 13, characterized in that: The step of comparing luminescence further comprises: The light emitting control signal EM is provided to the gates of the fourth transistor T4 and the fifth transistor T5, and the comparison reference signal SWEEP is provided to the gate of the sixth transistor T6 via the capacitor, the fourth transistor T4, the fifth transistor T5 and the sixth transistor T6 are turned on and connected as an inverter, so that the source of the sixth transistor T6 is the power input terminal of the inverter and is connected to the first power supply voltage VGH via the fourth transistor T4, so that the voltage of the power input terminal of the inverter is the first power supply voltage VGH; the gate of the sixth transistor T6 is the input terminal of the inverter and the voltage of the power input terminal of the inverter is PWMD-|V th6 |+ΔSWEEP; the drain of the sixth transistor T6 is the output end of the inverter and is connected to the reference power supply voltage REF via the fifth transistor T5, so that the voltage at the output end of the inverter is at a high level and the seventh transistor T7 remains cut off, wherein the size of the sixth transistor T6 is larger than the size of the fifth transistor T5, and the light emitting control signal EM is a pulse signal.

15. The μLED light emission control method according to claim 14, characterized in that: The step of comparing luminescence further comprises: The driving transistor T10 is turned on, so that the gate voltage of the driving transistor T10 maintains the PAMD signal, and the source of the driving transistor T10 is connected to the second power supply voltage VDD to provide the driving current, so that the μLED starts to emit light.

16. The μLED light emission control method according to claim 14, characterized in that: The step of comparing luminescence further comprises: The light-emitting control signal EM is provided to the gates of the eighth transistor T8 and the eleventh transistor T11, and the eighth transistor T8, the driving transistor T10 and the eleventh transistor T11 are turned on, so that the gate voltage of the driving transistor T10 maintains the PAMD signal, and the source of the driving transistor T10 is connected to the second power supply voltage VDD via the turned-on eleventh transistor T11 to provide the driving current, so that the μLED starts to emit light.

17. The μLED light emission control method according to claim 15 or 16, characterized in that: The step of comparing luminescence further comprises: When the comparison reference signal SWEEP increases linearly, the voltage PWMD-|V th6 |+ΔSWEEP is greater than VGH-|V th6 |, the sixth transistor T6 is turned off to reduce the voltage at the output end of the inverter to REF, so that the seventh transistor T7 is turned on to transmit the second power supply voltage VDD to the gate of the driving transistor T10 or set the gate of the driving transistor T10 to the second power supply voltage VDD, and the driving transistor T10 is turned off so that the μLED stops emitting light.

18. The μLED light emission control method according to claim 14, characterized in that: A light-emitting control signal EM1 is provided to the gate of the eleventh transistor T11 and a light-emitting control signal EM2 is provided to the eighth transistor T8, the eighth transistor T8, the driving transistor T10 and the eleventh transistor T11 are turned on, so that the gate voltage of the driving transistor T10 maintains the PAMD signal, and the source of the driving transistor T10 is connected to the second power supply voltage VDD via the turned-on eleventh transistor T11 to provide the driving current, so that the μLED starts to emit light, wherein the light-emitting control signal EM2 and the light-emitting control signal EM1 are pulse signals, and the falling edge of the light-emitting control signal EM2 lags behind the falling edge of the light-emitting control signal EM1.

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