Pixel driving circuit with adjustable current proportion and control method thereof

Abstract

The invention discloses a pixel driving circuit with an adjustable current proportion and a control method thereof. The driving circuit comprises a pulse width modulation (PWM) circuit module, a pulse amplitude modulation (PAM) circuit module and a current mirror circuit module, the PWM circuit module comprises a first transistor, a second transistor, a third transistor and a first capacitor; the PAM circuit module comprises a fourth transistor, a fifth transistor, a sixth transistor, a seventh transistor, an eighth transistor, a ninth transistor, a tenth transistor and a third capacitor; the current mirror circuit module comprises an eleventh transistor, a twelfth transistor and a thirteenth transistor; the occupied area of the pixel driving circuit is reduced, the transmittance of the transparent display screen is increased, and the resolution is improved.

Description

Technical Field

[0001] The present invention relates to the field of display technology, and in particular to a pixel driving circuit with adjustable current ratio and a control method thereof. Background Art

[0002] With the development of display technology, it can be divided into the following three display technologies according to the different display devices. These three display technologies each have their own advantages and disadvantages: OLED (organic light-emitting diode) display technology: a self-luminous display technology, in which each pixel is made of organic materials, and does not require a backlight source to achieve self-luminescence. It has the characteristics of fast response time and wide viewing angle, and can be used in the fields of smartphone displays and tablets; Mini-LED display technology: as an improved LED backlight technology, it can achieve local dimming and has a long life, and can be used in the field of high-end TVs; Micro-LED display technology, each pixel emits light independently, and has the characteristics of high brightness and high efficiency, and can be used in the field of ultra-large displays and virtual reality head-mounted displays. Micro-LED is also seen as the next generation of display technology.

[0003] However, Micro-LED pixel driving circuits face many challenges in practical applications. Currently, most of the Micro-LED display pixel driving circuits on the market generally follow the driving method of OLED and Mini-LED pixel driving circuits, namely pulse amplitude modulation. The working principle is as follows: the output current of the driving transistor is changed by changing the size of the data voltage, so that the diode emits light of different brightness. However, because the luminous efficiency of Micro-LED chips is low and unstable under low current driving, the display screen has color deviation problems under low current and low grayscale display; in addition, a pixel driving unit requires three groups of sub-pixel driving circuits to drive the three colors of R, G, and B respectively, so as to realize the display of different colors. This means that the display screen needs a lot of sub-pixel driving circuits, which makes a pixel unit need to occupy a large area, resulting in the display screen cannot achieve a high resolution under the premise of a certain size, reducing the display effect. Summary of the invention

[0004] Purpose of the invention: The purpose of the present invention is to provide a pixel driving circuit with adjustable current ratio and a control method thereof, so as to achieve the effect that three sub-pixels (R, G, B) share one pixel driving circuit, and the three driving currents can achieve a certain proportional relationship, thereby solving the problems existing in the background technology.

[0005] Technical solution: The pixel driving circuit with adjustable current ratio described in the present invention comprises: a pulse width modulation PWM circuit module, a pulse amplitude modulation PAM circuit module and a current mirror circuit module; wherein, The PWM circuit module includes: a first transistor, a second transistor, a third transistor and a first capacitor; Wherein, the gate of the first transistor is connected to the source of the third transistor, the source is connected to the PWM_VDD voltage, and the drain is connected to the source of the second transistor; The gate of the second transistor is connected to the first light emitting signal PWM_EM, and the drain is connected to the PAM circuit module through the second capacitor; The drain of the third transistor is connected to the gate of the first transistor through the node A, the gate is connected to the first scanning signal PWM_SCAN1, and the source is connected to the first reference voltage Vref1; The PAM circuit module includes: a fourth transistor, a fifth transistor, a sixth transistor, a seventh transistor, an eighth transistor, a ninth transistor, a tenth transistor and a third capacitor; The gate of the fourth transistor is connected to the drain of the sixth transistor, the third capacitor and the second capacitor through the node B, the source is connected to the drains of the eighth transistor and the ninth transistor through the node C, and the drain is connected to the source of the fifth transistor; The gate of the fifth transistor is connected to the third scan signal PAM_SCAN2, and the drain is connected to the node B; The gate of the sixth transistor is connected to the second scan signal PAM_SCAN1, and the source is connected to the first reference voltage Vref1; The gate of the seventh transistor is connected to the second light emitting signal PAM_EM, the source is connected to the source of the fifth transistor, and the drain is respectively connected to the anodes of the red, green, and blue micro light emitting diodes; The gate of the eighth transistor is connected to the third scan signal PAM_SCAN2, the source is connected to the data voltage PAM_DATA, and the drain is connected to the drain of the ninth transistor through the node C; The gate of the ninth transistor is connected to the second light emitting signal PAM_EM, and the source is connected to the PAM_VDD voltage; The current mirror circuit module includes: an eleventh transistor, a twelfth transistor, and a thirteenth transistor; The sources of the eleventh, twelfth and thirteenth transistors are respectively connected to the cathodes of the red, green and blue micro-LEDs, the drains are commonly connected to the Vss voltage, and the gates are connected to each other; The gate of the eleventh transistor is connected to the source, and the gate of the twelfth transistor is connected to the source.

[0006] Furthermore, in the current mirror circuit, the eleventh transistor, the twelfth transistor, and the thirteenth transistor have different width-to-length ratios (W / L), so that the currents flowing through the three micro-LEDs satisfy the following proportional relationship: ; ; in, , , are the width-to-length ratios of the eleventh transistor, the twelfth transistor, and the thirteenth transistor respectively; , , Respectively represents the luminous current of the three colors red, green and blue.

[0007] Furthermore, the PWM circuit module is connected to the node B of the PAM circuit module via the second capacitor, and is used to control the on-time of the light-emitting path via the voltage scanning signal SWEEP.

[0008] Furthermore, one end of the third capacitor of the PAM circuit module is connected to the node B, and the other end is connected to the PAM_VDD voltage, which is used to store the data voltage PAM_DATA and the threshold voltage V TH The difference.

[0009] Furthermore, one end of the first capacitor is connected to the node A, and the other end is connected to the voltage scanning signal SWEEP, so as to store the voltage difference in the initialization stage.

[0010] Furthermore, the ninth transistor is turned on in the light emitting stage (b) to transfer the PAM_VDD voltage to the node C to maintain the stability of the light emitting path.

[0011] The pixel driving circuit control method with adjustable current ratio described in the present invention includes a PWM initialization stage, a PAM initialization stage and a light emitting stage, and includes the following steps: PWM initialization stage: The first scanning signal PWM_SCAN1 is at a low potential, and the other signals are at a high potential; The third transistor is turned on, the voltage of the node A is initialized to the first reference voltage Vref1, and the voltage across the first capacitor is SWEEP-Vref1; PAM initialization stage: the second scan signal PAM_SCAN1 is at a low potential, and the other signals are at a high potential; the sixth transistor and the tenth transistor are turned on, the voltage of the node B is initialized to the first reference voltage Vref1, and the voltage of the node D is initialized to the second reference voltage Vref2; PAM data writing stage: the third scan signal PAM_SCAN2 is at a low potential, and the other signals are at a high potential; the fifth transistor and the eighth transistor are turned on, and the voltage of the node B is , the voltage at node C is ;in, is the data voltage of the PAM circuit, a threshold voltage of the fourth transistor; Lighting stage: (a) The first light-emitting signal PWM_EM is at a low potential, the voltage scanning signal SWEEP decreases linearly, and the voltage at node A is ; Wherein Vref1 is the first reference voltage, is the change of the voltage scanning signal SWEEP; (b) The first light-emitting signal PWM_EM and the second light-emitting signal PAM_EM are both at low potentials, the PAM circuit forms a light-emitting path, and the red, green, and blue micro-LEDs emit light in proportion to the current; (c) When the voltage at node A is lower than the threshold voltage of the first transistor, the light emitting path is closed.

[0012] Furthermore, in the light emitting stage (b), the driving current of the red micro-LED is: ; in, is the driving current of the red diode, is the carrier mobility, is the gate oxide capacitance, W and L are the width and length of the fourth transistor respectively, is the data voltage of the PAM circuit, is the power supply voltage of the PAM circuit, is the threshold voltage of the fourth transistor; is the gate-source voltage difference of the fourth transistor T4.

[0013] Furthermore, in the light emitting stage (c), the voltage of the node B rises from to , the fourth transistor is gradually turned off, and the light emitting path is terminated.

[0014] Furthermore, the anodes of the red, green and blue micro light emitting diodes are connected to the PAM circuit module through the seventh transistor, and the cathodes are connected to the Vss voltage through the current mirror circuit module.

[0015] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: the present invention uses the PWM module circuit voltage to control the opening and closing time of the PAM module light-emitting path, realizes voltage-controlled PWM dimming, can improve the light-emitting efficiency of the micro-light-emitting diode, and reduce the power consumption of the display screen; and realizes the effect of three sub-pixels (R, G, B) sharing one pixel driving circuit, and the three driving currents can achieve a certain proportional relationship, reduce the area occupied by the pixel driving circuit, increase the transmittance of the transparent display screen, and improve the resolution. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic diagram of a circuit module of the present invention; Figure 2 is a circuit diagram of the present invention; Figure 3 It is a circuit timing diagram of the present invention; Figure 4A schematic diagram of a circuit of a PAM initialization stage in the method of the present invention; Figure 5 A circuit diagram of the PWM initialization stage in the method of the present invention; Figure 6 A circuit diagram of the PAM data writing stage in the method of the present invention; Figure 7 is a circuit diagram of the light emitting stage (a) in the method of the present invention; Figure 8 is a circuit diagram of the light emitting stage (b) in the method of the present invention; Fig. 9 FIG. 4 is a schematic diagram of a circuit in the light emitting stage (c) of the method of the present invention. DETAILED DESCRIPTION

[0017] The technical solution of the present invention is further described below in conjunction with the accompanying drawings.

[0018] like Figure 1 As shown, an embodiment of the present invention provides a Micro-LED pixel driving circuit with adjustable current ratio, including three circuit modules, including: a PWM circuit module, a PAM circuit module and a current mirror circuit module.

[0019] The specific circuit structure is as follows: Figure 2 As shown, it includes: a first transistor T1, a second transistor T2, a third transistor T3, a fourth transistor T4, a fifth transistor T5, a sixth transistor T6, a seventh transistor T7, an eighth transistor T8, a ninth transistor T9, a tenth transistor T10, an eleventh transistor T11, a twelfth transistor T12, a thirteenth transistor T13, a first capacitor C1, a second capacitor C2 and a third capacitor C3.

[0020] The specific connection method is as follows: the PWM circuit connection method includes: the gate of the first transistor T1 is connected to the source of the third transistor T3, the source of the first transistor T1 is connected to the PWM_VDD voltage, and the drain of the first transistor T1 is connected to the source of the second transistor T2. The gate of the second transistor T2 is connected to the first light-emitting signal PWM_EM, and the drain of the second transistor T2 is connected to one end of the second capacitor C2. The drain of the third transistor T3 is connected to the gate of the first transistor T1 through the node A, the gate of the third transistor T3 is connected to the first scan signal PWM_SCAN1, and the source of the third transistor T3 is connected to the first reference voltage Vref1. The PWM module is connected to the PAM module through the second capacitor C2.

[0021] The PAM circuit connection method includes: the gate of the fourth transistor T4 is connected to the drain of the sixth transistor T6, the third capacitor C3 and one end of the second capacitor C2 through the node B, the source of the fourth transistor T4 is connected to the drain of the eighth transistor T8 and the ninth transistor T9 through the node C, and the drain of the fourth transistor T4 is connected to the source of the fifth transistor T5. The gate of the fifth transistor T5 is connected to the third scan signal PAM_SCAN2, and the drain of the fifth transistor T5 is connected to the node B. The gate of the sixth transistor T6 is connected to the second scan signal PAM_SCAN1, and the source of the sixth transistor T6 is connected to the first reference voltage Vref1. The gate of the seventh transistor T7 is connected to the second light-emitting signal PAM_EM, the source of the seventh transistor T7 is connected to the source of the fifth transistor T5, and the drain of the seventh transistor T7 is connected to the three light-emitting units RLED, GLED and BLED respectively. The gate of the eighth transistor T8 is connected to the third scan signal PAM_SCAN2, the source of the eighth transistor T8 is connected to the data voltage PAM_DATA, and the drain of the eighth transistor T8 is connected to the drain of the ninth transistor T9 through the node C. The gate of the ninth transistor T9 is connected to the second light-emitting signal PAM_EM, and the source of the ninth transistor T9 is connected to the PAM_VDD voltage. The PAM module is connected to the current mirror circuit module through three light-emitting units.

[0022] The current mirror circuit connection method includes: the sources of the eleventh transistor T11, the twelfth transistor T12 and the thirteenth transistor T13 are connected to the cathodes of RLED, GLED and BLED respectively, the drains of the eleventh transistor T11, the twelfth transistor T12 and the thirteenth transistor T13 are commonly connected to the Vss voltage, the gates of the eleventh transistor T11, the twelfth transistor T12 and the thirteenth transistor T13 are connected together, the gate of the eleventh transistor T11 is connected to the source, and the gate of the twelfth transistor T12 is connected to the source.

[0023] like Figure 3 As shown, the first scanning signal PWM_SCAN1, the second scanning signal PAM_SCAN1, the third scanning signal PAM_SCAN2, the first light-emitting signal PWM_EM, the second light-emitting signal PAM_EM, and the voltage scanning signal SWEEP respectively provide high and low potentials. The working stage of the Micro-LED current proportional adjustable pixel driving circuit is divided into four stages, including: PWM initialization stage, PAM initialization stage, PAM data writing stage and light-emitting stage, wherein the light-emitting stage includes three stages (a), (b), and (c).

[0024] The embodiment of the present invention further provides a driving method of a Micro-LED pixel driving circuit, comprising the following steps: like Figure 3 and Figure 4As shown, in the PWM initialization stage: the first scanning signal PWM_SCAN1 provides a low potential, the second scanning signal PAM_SCAN1, the third scanning signal PAM_SCAN2, the first light-emitting signal PWM_EM, the second light-emitting signal PAM_EM, and the voltage scanning signal SWEEP provide a high potential. The third transistor T3 is turned on, the first transistor T1, the second transistor T2, the fourth transistor T4, the fifth transistor T5, the sixth transistor T6, the seventh transistor T7, the eighth transistor T8, the ninth transistor T9, and the tenth transistor T10 are all turned off. At this time, the gate voltage value of the PWM module driving transistor T1 at the node A is initialized to the reference voltage, and the voltage difference across the first capacitor C1 is; Combination Figure 3 and Figure 5 As shown, in the PAM initialization stage: the second scanning signal PAM_SCAN1 provides a low potential, and the first scanning signal PWM_SCAN1, the third scanning signal PAM_SCAN2, the first light-emitting signal PWM_EM, the second light-emitting signal PAM_EM, and the voltage scanning signal SWEEP provide a high potential. The sixth transistor T6 and the tenth transistor T10 are turned on, and the first transistor T1, the second transistor T2, the third transistor T3, the fourth transistor T4, the fifth transistor T5, the seventh transistor T7, the eighth transistor T8, and the ninth transistor T9 are all turned off. At this time, the gate voltage value of the PAM module driving transistor T4 at the node B is initialized to the reference voltage, and the anode voltage value of the micro light-emitting diode at the node D is initialized to the reference voltage. At this time, the voltage difference across the first capacitor C3 is, and the voltage difference across the three micro light-emitting diodes is the turn-on voltage, and no light is emitted.

[0025] Combination Figure 3 and Figure 6 As shown, in the PAM data writing stage: the third scanning signal PAM_SCAN2 provides a low potential, and the first scanning signal PWM_SCAN1, the second scanning signal PAM_SCAN1, the first light-emitting signal PWM_EM, the second light-emitting signal PAM_EM, and the voltage scanning signal SWEEP provide a high potential. The fifth transistor T5 and the eighth transistor T8 are turned on, and the first transistor T1, the second transistor T2, the third transistor T3, the fourth transistor T4, the sixth transistor T6, the seventh transistor T7, the ninth transistor T9, and the tenth transistor T10 are all turned off. At this time, the gate voltage value of the PAM module driving transistor T4 at the node B is , the voltage value at the node C is , the voltage difference across the first capacitor C3 is , and the micro light-emitting diode maintains the previous state and does not emit light; is the power supply voltage of the PAM circuit; The threshold voltage of the fourth transistor T4, is the power supply voltage of the PAM circuit.

[0026] Combination Figure 7~Figure 9 As shown, the light-emitting stage: the light-emitting stage is divided into three stages, as follows: like Figure 7 As shown, in stage (a): the first light-emitting signal PWM_EM provides a low potential, the first scanning signal PWM_SCAN1, the second scanning signal PAM_SCAN1, the third scanning signal PAM_SCAN2, and the second light-emitting signal PAM_EM provide a high potential, and the voltage scanning signal SWEEP starts to decrease linearly from a high potential. The second transistor T2 is turned on, and the first transistor T1, the third transistor T3, the fourth transistor T4, the fifth transistor T5, the sixth transistor T6, the seventh transistor T7, the eighth transistor T8, the ninth transistor T9, and the tenth transistor T10 are all turned off. At this time, the voltage value at node A is that the potential at nodes B, C, and D maintains the previous state, and the micro-LED does not emit light. Among them, is the change of the voltage scanning signal SWEEP.

[0027] like Figure 8 As shown, in stage (b): the first light-emitting signal PWM_EM and the second light-emitting signal PAM_EM provide a low potential, the first scanning signal PWM_SCAN1, the second scanning signal PAM_SCAN1, and the third scanning signal PAM_SCAN2 provide a high potential, and the voltage scanning signal SWEEP maintains the previous state. The second transistor T2, the seventh transistor T7, and the ninth transistor T9 are all turned on, and the first transistor T1, the transistor T3, the fourth transistor T4, the fifth transistor T5, the sixth transistor T6, the eighth transistor T8, and the tenth transistor T10 are all turned off. At this time, a partial light-emitting path of the PAM circuit is formed, and a driving current passes through the micro light-emitting diode RLED. At this time, the driving current formula is: ; in, is the driving current of the red diode, is the carrier mobility, is the gate oxide capacitance, W and L are the width and length of the fourth transistor T4, respectively. is the data voltage of the PAM circuit, is the power supply voltage of the PAM circuit, is the threshold voltage of the fourth transistor T4; is the gate-source voltage difference of the fourth transistor T4.

[0028] Due to the existence of the current mirror circuit, according to the different width-to-length ratios of the eleventh transistor T11, the twelfth transistor T12, and the thirteenth transistor T13, the currents flowing through the three micro-LEDs can present a proportional relationship, as follows: ; ; in, , , are the width-to-length ratios of the eleventh transistor, the twelfth transistor, and the thirteenth transistor respectively; , , respectively represent the luminous current of red, green and blue colors; , , Respectively represents the luminous current of the three colors red, green and blue.

[0029] This circuit structure can achieve the effect of three sub-pixels (R, G, B) sharing one pixel driving circuit, and the three driving currents can achieve a certain proportional relationship, reducing the area occupied by the pixel driving circuit, increasing the transmittance of the transparent display screen, and improving the resolution.

[0030] like Fig. 9 As shown, in stage (c): when the voltage at node A is , the first transistor T1 is slowly turned on from off, and at this time, the voltage is conducted through the first transistor T1 and the second transistor T2 to one end of the second capacitor, so that the voltage value at node B increases from to, and the fourth transistor T4 slowly turns from on to off, the light path disappears, and the micro-LED stops emitting light. Through the above circuit structure, the PWM module circuit voltage is used to control the opening and closing time of the PAM module light path, and voltage-controlled PWM dimming is realized, which can improve the light-emitting efficiency of the micro-LED and reduce the power consumption of the display screen.

Claims

1. A pixel driving circuit with adjustable current ratio, characterized in that: include: A pulse width modulation (PWM) circuit module, a pulse amplitude modulation (PAM) circuit module and a current mirror circuit module; wherein the PWM circuit module comprises: a first transistor (T1), a second transistor (T2), a third transistor (T3) and a first capacitor (C1); wherein the gate of the first transistor (T1) is connected to the source of the third transistor (T3), the source is connected to the PWM_VDD voltage, and the drain is connected to the source of the second transistor (T2); the gate of the second transistor (T2) is connected to the first light-emitting signal PWM_EM, and the drain is connected to the PAM circuit module through the second capacitor (C2); the drain of the third transistor (T3) is connected to the gate of the first transistor (T1) through node A, the gate is connected to the first scanning signal PWM_SCAN1, and the source is connected to the first reference voltage (Vref1); the PAM circuit module comprises: a fourth transistor (T4), a fifth transistor (T5), a sixth transistor (T6), a seventh transistor (T7), an eighth transistor (T8), a ninth transistor (T9), a tenth transistor (T10) and a third capacitor (C3); wherein , the gate of the fourth transistor (T4) is connected to the drain of the sixth transistor (T6), the third capacitor (C3) and the second capacitor (C2) through the node B, the source is connected to the drains of the eighth transistor (T8) and the ninth transistor (T9) through the node C, and the drain is connected to the source of the fifth transistor (T5); the gate of the fifth transistor (T5) is connected to the third scanning signal PAM_SCAN2, and the drain is connected to the node B; the gate of the sixth transistor (T6) is connected to the second scanning signal PAM_SCAN1, and the source is connected to the first reference voltage (Vref1); the gate of the seventh transistor (T7) is connected to the second light-emitting signal PAM_EM, the source is connected to the source of the fifth transistor (T5), and the drain is respectively connected to the anodes of the red, green and blue micro light-emitting diodes; the gate of the eighth transistor (T8) is connected to the third scanning signal PAM_SCAN2, the source is connected to the data voltage PAM_DATA, and the drain is connected to the drain of the ninth transistor (T9) through the node C; the gate of the ninth transistor (T9) is connected to the second light-emitting signal PAM_EM, and the source is connected to the PAM_VDD voltage; The current mirror circuit module includes: an eleventh transistor (T11), a twelfth transistor (T12), and a thirteenth transistor (T13); the sources of the eleventh transistor (T11), the twelfth transistor (T12), and the thirteenth transistor (T13) are respectively connected to the cathodes of the red, green, and blue micro-light-emitting diodes, the drains are commonly connected to the Vss voltage, and the gates are connected to each other; the gate of the eleventh transistor (T11) is connected to the source, and the gate of the twelfth transistor (T12) is connected to the source.

2. The pixel driving circuit with adjustable current ratio according to claim 1, characterized in that: In the current mirror circuit: the eleventh transistor (T11), the twelfth transistor (T12), and the thirteenth transistor (T13) have different width-to-length ratios, so that the currents flowing through the three micro-LEDs satisfy the following proportional relationship: ； ； in, , , are respectively the width-to-length ratios of the eleventh transistor (T11), the twelfth transistor (T12), and the thirteenth transistor (T13); , , Respectively represents the luminous current of the three colors red, green and blue.

3. The pixel driving circuit with adjustable current ratio according to claim 1, characterized in that: The PWM circuit module is connected to the node B of the PAM circuit module via a second capacitor (C2) and is used to control the on-time of the light-emitting path via a voltage sweep signal (SWEEP).

4. The pixel driving circuit with adjustable current ratio according to claim 1, characterized in that: One end of the third capacitor (C3) of the PAM circuit module is connected to the node B, and the other end is connected to the PAM_VDD voltage, which is used to store the data voltage PAM_DATA and the threshold voltage (V TH ) difference.

5. The pixel driving circuit with adjustable current ratio according to claim 1, characterized in that: One end of the first capacitor (C1) is connected to the node A, and the other end is connected to the voltage scanning signal SWEEP, and is used to store the voltage difference in the initialization stage.

6. The pixel driving circuit according to claim 1, characterized in that: The ninth transistor (T9) is turned on in the light emitting phase (b) to transfer the PAM_VDD voltage to the node C to maintain the stability of the light emitting path.

7. A method for controlling a pixel driving circuit with adjustable current ratio, characterized in that: It includes a PWM initialization phase, a PAM initialization phase and a light-emitting phase, and includes the following steps: PWM initialization stage: The first scanning signal PWM_SCAN1 is at a low potential, and the other signals are at a high potential; the third transistor (T3) is turned on, the voltage of the node A is initialized to the first reference voltage Vref1, and the voltage across the first capacitor (C1) is SWEEP-Vref1; PAM initialization stage: the second scan signal PAM_SCAN1 is at a low potential, and the other signals are at a high potential; the sixth transistor (T6) and the tenth transistor (T10) are turned on, the voltage of the node B is initialized to the first reference voltage Vref1, and the voltage of the node D is initialized to the second reference voltage Vref2; PAM data writing stage: the third scan signal PAM_SCAN2 is at a low potential, and the other signals are at a high potential; the fifth transistor (T5) and the eighth transistor (T8) are turned on, and the voltage of node B is , the voltage at node C is ; in, is the data voltage of the PAM circuit, a threshold voltage of a fourth transistor (T4); Lighting stage: (a) The first light-emitting signal PWM_EM is at a low potential, the voltage scanning signal SWEEP decreases linearly, and the voltage at node A is ; Wherein Vref1 is the first reference voltage, is the change of the voltage sweep signal SWEEP; (b) The first light-emitting signal PWM_EM and the second light-emitting signal PAM_EM are both at low potentials, the PAM circuit forms a light-emitting path, and the red, green, and blue micro-LEDs emit light in proportion to the current; (c) When the voltage at node A is lower than the threshold voltage of the first transistor (T1), the light emitting path is closed.

8. The method for controlling a pixel driving circuit with adjustable current ratio according to claim 7, characterized in that: In the light-emitting stage (b), the driving current of the red micro-LED is: ； in, is the driving current of the red diode, is the carrier mobility, is the gate oxide capacitance, W and L are the width and length of the fourth transistor (T4), respectively. is the data voltage of the PAM circuit, is the power supply voltage of the PAM circuit, is the threshold voltage of the fourth transistor (T4); is the gate-source voltage difference of the fourth transistor T4.

9. The method for controlling a pixel driving circuit with adjustable current ratio according to claim 7, characterized in that: In the light emitting stage (c), the voltage of the node B rises from to , the fourth transistor (T4) is gradually turned off, and the light emitting path is terminated.

10. The pixel driving circuit with adjustable current ratio according to claim 1, characterized in that: The anodes of the red, green and blue micro-light emitting diodes are connected to the PAM circuit module through the seventh transistor (T7), and the cathodes are connected to the Vss voltage through the current mirror circuit module.

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