Micro LED driving circuit, driving system, display panel and pixel driving method

Abstract

A Micro LED driving circuit, driving system, display panel, and pixel driving method are disclosed. The Micro LED driving circuit includes: a first MOS transistor (10), the gate of which is used to receive an enable signal (EN); a first inverter (40), one end of which is electrically connected to the gate of the first MOS transistor (10), and the other end of which is electrically connected to the substrate of the first MOS transistor (10); a second MOS transistor (20), the source of the first MOS transistor (10) and the source of the second MOS transistor (20) are electrically connected to the same voltage source (VDD), and the gate of the second MOS transistor (20) is used to receive a control signal (SF); and a current mirror (30), the drain of the first MOS transistor (10) and the drain of the second MOS transistor (20) are both electrically connected to the current mirror (30), and the current mirror (30) has an input interface (Lin) for receiving external current and an output interface for being electrically connected to an external light-emitting unit (50).

Description

Technical Field

[0001] This invention relates to the field of Micro LED display driving technology, and more specifically, to Micro LED driving circuits, driving systems, display panels, and pixel driving methods. Background Technology

[0002] Micro LED displays refer to a display technology that utilizes micrometer-scale LED pixel units and assembles them onto a driving panel to form a high-density LED display array. Due to the small size, high integration, and self-emissive nature of Micro LED chips, they offer significant advantages over LCD and OLED displays in terms of brightness, resolution, contrast ratio, energy consumption, lifespan, response speed, and thermal stability. Early LED displays used a combination of red, green, and blue (R / G / B) LEDs as pixels.

[0003] For reference Figure 1 The diagram shows a schematic of an existing Micro LED display driver circuit. The existing Micro LED driver circuit includes PMOS transistors M1 and M2, a current mirror, and an LED. The current mirror consists of two mirror-symmetrically arranged PMOS transistors M3 and M4. The sources (also called S-terminals) of PMOS transistors M1 and M2 are connected to the chip operating voltage VDD. The gate (also called G-terminal) of PMOS transistor M1 is electrically connected to the enable signal EN. The G-terminal of PMOS transistor M1 is electrically connected to the display control signal SF. The drain (also called D-terminal) of PMOS transistor M1 is electrically connected to the S-terminal of PMOS transistor M3, and the D-terminal of PMOS transistor M2 is electrically connected to the S-terminal of PMOS transistor M4. The gate (G) of PMOS transistor M3 and the gate (G) of PMOS transistor M4 are electrically connected. The gate (G) of PMOS transistor M3 and the drain (D) of PMOS transistor M3 are electrically connected. The drain of PMOS transistor M3 is electrically connected to an external current Lin. The drain of PMOS transistor M4 is electrically connected to the anode of the LED. The cathode of the display pixel LED is grounded.

[0004] Based on the analysis of the existing Micro LED display driving circuit principles: Firstly, Figure 1 When PMOS transistors M1 and M2 are turned on, there will be an on-resistance. On resistance The larger the on-resistance, the higher the loss. Therefore, to reduce loss, it is desirable to minimize the on-resistance. The smaller the better. Secondly, when Figure 1 When PMOS transistors M1 and M2 are in the off state, under ideal conditions, the cutoff resistance is... The current approaches infinity, and the cutoff current is zero. However, due to the non-ideal characteristics of the device, even when both the first MOSFET M1 and the second MOSFET M2 are in the cutoff state, there will still be a small leakage current. Since Micro LEDs are sensitive to current, even a small current will cause weak light emission, affecting the working performance of Micro LEDs. Summary of the Invention

[0005] In view of the technical problems existing in the current Micro LED driving circuits mentioned in the background art, the purpose of this invention is to provide a Micro LED driving circuit, driving system, display panel and pixel driving method, which can overcome the defects of the prior art. It uses an inverter to electrically connect the gate and substrate of the MOS transistor so that the gate and substrate of the MOS transistor have opposite potentials, thereby reducing the on-resistance of the driving circuit and increasing the off-resistance.

[0006] To achieve the above objectives, the present invention discloses a Micro LED driving circuit, characterized by comprising:

[0007] A first MOS transistor, the gate of which is used to receive an enable signal;

[0008] A first inverter, one end of which is electrically connected to the gate of the first MOS transistor, and the other end of which is electrically connected to the substrate of the first MOS transistor;

[0009] A second MOSFET, wherein the sources of the first MOSFET and the second MOSFET are electrically connected to the same voltage source, and the gate of the second MOSFET is used to receive a control signal; and

[0010] A current mirror is provided, wherein the drains of the first MOS transistor and the second MOS transistor are electrically connected to the current mirror, and the current mirror has an input interface for receiving an external current and an output interface for being electrically connected to an external light-emitting unit.

[0011] The current mirror mentioned above includes:

[0012] A third MOSFET, wherein the source of the third MOSFET is electrically connected to the drain of the first MOSFET, the drain of the third MOSFET serves as the input interface, and the drain of the third MOSFET is electrically connected to the gate of the third MOSFET; and

[0013] A fourth MOS transistor, the source of which is electrically connected to the drain of the second MOS transistor, the drain of which serves as the output interface, and the gate of the third MOS transistor is electrically connected to the gate of the fourth MOS transistor.

[0014] The gate of the first MOS transistor is electrically connected to the substrate of the third MOS transistor, and the gate of the second MOS transistor is electrically connected to the substrate of the fourth MOS transistor.

[0015] The first MOS transistor, the second MOS transistor, the third MOS transistor, and the fourth MOS transistor are PMOS transistors.

[0016] The device further includes a second inverter, one end of which is electrically connected to the gate of the second MOS transistor, and the other end of which is electrically connected to the substrate of the second MOS transistor.

[0017] The first inverter is used to reverse the phase of the signal at the gate of the first MOS transistor by 180°, and the second inverter is used to reverse the phase of the signal at the gate of the second MOS transistor by 180°.

[0018] A Micro LED driving system is also disclosed, characterized in that it includes:

[0019] The aforementioned Micro LED driving circuit; and

[0020] A light-emitting unit is electrically connected to an output interface of the Micro LED driving circuit.

[0021] Wherein, the light-emitting unit is an LED, the output interface is electrically connected to the anode of the LED, and the cathode of the LED is grounded.

[0022] A Micro LED display panel is also disclosed, characterized in that it comprises an array of two Micro LED driving systems as described above.

[0023] A pixel driving method for Micro LEDs is also disclosed, characterized by comprising the following steps:

[0024] A drive signal is input to the gate of a MOSFET in a drive circuit; and

[0025] Based on the driving signal, an inverted driving signal with a 180° phase difference from the driving signal is input to the substrate of the MOS transistor.

[0026] The step of inputting the drive signal to the gate of the MOS transistor in the drive circuit further includes:

[0027] A first driving signal is input to the gate of a first MOS transistor in the driving circuit, and a second driving signal is input to the gate of a second MOS transistor in the driving circuit.

[0028] Furthermore, the step of inputting an inverted drive signal with a 180° phase difference from the drive signal to the substrate of the MOS transistor based on the drive signal further includes the following steps:

[0029] Based on the first driving signal, a first inverted driving signal with a 180° phase difference from the first driving signal is input to the substrate of the first MOS transistor; and

[0030] Based on the second driving signal, a second inverted driving signal with a 180° phase difference from the second driving signal is input to the substrate of the second MOS transistor.

[0031] This further includes the following steps:

[0032] By using an inverter positioned between the gate and substrate of the MOS transistor, the signal phase of the gate of the MOS transistor is changed, so that the substrate of the MOS transistor has the opposite phase.

[0033] This further includes the following steps:

[0034] By using a first inverter disposed between the gate and substrate of the first MOS transistor, the signal phase of the gate of the first MOS transistor is changed; and

[0035] The signal phase of the gate of the second MOS transistor is changed by a second inverter disposed between the gate and the substrate of the second MOS transistor.

[0036] Therefore, the present invention can achieve the following beneficial effects: 1. By using an inverter to electrically connect the gate and substrate of the MOS transistor, the gate and substrate of the MOS transistor have opposite potentials, thereby reducing the on-resistance of the drive circuit and increasing the off-resistance; 2. The gate of the first MOS transistor is electrically connected to the substrate of the third MOS transistor of the current mirror, and the gate of the second MOS transistor is electrically connected to the substrate of the fourth MOS transistor of the current mirror, which can reduce the magnitude of the turn-on voltage, thereby helping to reduce the mismatch of the current mirror. Attached Figure Description

[0037] The above and other objects, features and advantages of this disclosure will become more apparent from the more detailed description of exemplary embodiments thereof taken in conjunction with the accompanying drawings, wherein like reference numerals generally denote like parts.

[0038] Figure 1 This is a Micro LED driving circuit based on existing technology.

[0039] Figure 2 This is a schematic diagram of the circuit principle of the Micro LED driving system of the present invention.

[0040] Figure 3 This is a schematic diagram of a modified embodiment of the Micro LED driving system of the present invention.

[0041] Figure 4 This is a flowchart of the Micro LED driving method of the present invention. Detailed Implementation

[0042] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0043] refer to Figure 2 This invention discloses a Micro LED driving system, including a first MOSFET 10, a second MOSFET 20, a current mirror 30, a first inverter 40, and a light-emitting unit 50. The gate of the first MOSFET 10 is used to receive an enable signal EN. One end of the first inverter 40 is electrically connected to the gate of the first MOSFET 10, and the other end is electrically connected to the substrate of the first MOSFET 10. The first inverter 40 is used to invert the phase of the signal at the gate of the first MOSFET 10 by 180 degrees. The source of the first MOSFET 10 and the source of the second MOSFET 20 are electrically connected to the same voltage source VDD. The gate of the second MOSFET 20 is used to receive a control signal SF. The drains of both the first MOSFET 10 and the second MOSFET 20 are electrically connected to the current mirror 30. The current mirror 30 has an input interface for receiving an external current Lin and an output interface for electrically connecting to an external light-emitting unit 50. The light-emitting unit 50 is electrically connected to the output interface of the current mirror 30. In some embodiments, both the first MOSFET 10 and the second MOSFET 20 are SOI devices (Silicon-On-Insulator).

[0044] The first MOSFET 10 acts as the master control switch. When the first MOSFET 10 is off, the light-emitting unit 50 cannot be lit regardless of the switching state of the second MOSFET 20. The second MOSFET 20 acts as the direct control switch for the light-emitting unit 50. When the first MOSFET 10 is on, the switching state of the second MOSFET 20 can control whether the light-emitting unit 50 is lit. The current mirror 30 provides constant current protection for the input current of the light-emitting unit 50.

[0045] When both the first MOSFET 10 and the second MOSFET 20 are in the on-state, there will be an on-equivalent resistance in the circuit. The calculation formula is as follows:

[0046]

[0047] In the above In the calculation formula, Represents the gate voltage. Represents the turn-on voltage. Represents the MOSFET constant. Represents the length of the MOSFET. This represents the width of the MOSFET.

[0048] In the technical solution provided by the present invention, the gate and substrate (also referred to as B-terminal) of the first MOS transistor 10 are electrically connected by a first inverter 40, so that the signal phase difference between the gate and substrate of the first MOS transistor 10 is 180 degrees.

[0049] When the drive circuit is in the ON state, and the enable signal EN is low, the first MOSFET 10 is turned on. Due to the inversion effect of the first inverter 40, the substrate of the first MOSFET 10 is at a high level, and the voltage between the source and substrate of the first MOSFET 10 is... Decrease, based on the turn-on voltage (can also be represented as) The calculation formula can determine along with It decreases as it decreases. The calculation formula is as follows:

[0050]

[0051] exist In the calculation formula, Represents the initial voltage. The voltage represents the voltage between the source and the substrate, and the rest are MOS transistor constants.

[0052] according to The calculation formula, when the opening voltage is... When the resistance decreases, the on-state equivalent resistance... This reduces losses, which helps to decrease losses when the circuit is in the conducting state.

[0053] When the drive circuit is in the off state, when the enable signal is high, the first MOSFET 10 is turned off. Due to the action of the first inverter 40, the substrate of the first MOSFET 10 is at a low level, and the voltage between the source and the substrate is... Increase, based on the turn-on voltage (can also be represented as) The calculation formula can determine along with It increases with the increase of [the value]. Based on the cutoff equivalent resistance... The calculation formula can determine With the turn-on voltage The equivalent resistance increases with the increase of [something]. The calculation formula is as follows:

[0054]

[0055]

[0056] When the drive circuit is in the off state, when the equivalent resistance Increasing the size of the light source can reduce the leakage current, reduce the blackness of the light-emitting unit 50 when it is in the off state, and improve the display performance.

[0057] refer to Figure 2 Furthermore, the current mirror 30 includes a third MOSFET 31 and a fourth MOSFET 32. The source of the third MOSFET 31 is electrically connected to the drain of the first MOSFET 10, and the drain of the third MOSFET 31 serves as an input interface. The drain of the third MOSFET 31 is also electrically connected to its gate. The source of the fourth MOSFET 32 is electrically connected to the drain of the second MOSFET 20, and the drain of the fourth MOSFET 32 serves as an output interface. The gate of the third MOSFET 31 is also electrically connected to its gate.

[0058] refer to Figure 3 In some embodiments, the gate of the first MOSFET 10 is electrically connected to the substrate of the third MOSFET 31, and the gate of the second MOSFET 20 is electrically connected to the substrate of the fourth MOSFET 32.

[0059] When the enable or control signal is low, based on the MOS conduction characteristics, the first MOS transistor 10 and the second MOS transistor 20 are turned on. The current mirror 30, composed of the third MOS transistor 31 and the fourth MOS transistor 32, also begins to operate. Since the gate of the first MOS transistor 10 is electrically connected to the substrate of the third MOS transistor 31, and the gate of the second MOS transistor 20 is electrically connected to the substrate of the fourth MOS transistor 32, the substrates of the third MOS transistor 31 and the fourth MOS transistor 32 are at a low level. Therefore, the turn-on voltage of the third MOS transistor 31 and the fourth MOS transistor 32 decreases. According to the mismatch calculation formula for the current mirror 30, the turn-on voltage can be determined. Reducing the size helps decrease the mismatch of the current mirror. The formula for calculating the mismatch of the current mirror (30) is as follows:

[0060]

[0061] When the enable or control signal is high, based on the conduction characteristics of the MOSFETs, the first MOSFET 10 and the second MOSFET 20 are turned off, and the current mirror 30 composed of the third MOSFET 31 and the fourth MOSFET 32 also stops working. Since the gate of the first MOSFET 10 is electrically connected to the substrate of the third MOSFET 31, and the gate of the second MOSFET 20 is electrically connected to the substrate of the fourth MOSFET 32, the turn-on voltage of the third MOSFET 31 and the fourth MOSFET 32 is... It is at a high level, that is, the turn-on voltage of the third MOSFET 31 and the fourth MOSFET 32. Increase the size of the current, thereby reducing leakage current.

[0062] In some embodiments, the first MOSFET 10, the second MOSFET 20, the third MOSFET 31, and the fourth MOSFET 32 are all PMOS transistors. In some embodiments, the first MOSFET 10, the second MOSFET 20, the third MOSFET 31, and the fourth MOSFET 32 are all NMOS transistors.

[0063] refer to Figure 2 The Micro LED driving system further includes a second inverter 60, one end of which is electrically connected to the gate of the second MOSFET 20, and the other end is electrically connected to the substrate of the second MOSFET 20. The second inverter 60 can reverse the phase of the signal at the gate of the second MOSFET 20 by 180 degrees. Its working principle in the driving system is similar to that of the first inverter 40, and will not be described in detail here.

[0064] In some implementations, the light-emitting unit 50 is an LED, the output interface of the current mirror 30 is connected to the anode of the LED, and the cathode of the LED is grounded.

[0065] In some embodiments, a Micro LED display panel is further provided, including a driving panel and a Micro LED array, wherein the Micro LED array is disposed on the driving panel, and the driving panel includes a Micro LED driving system array corresponding to the Micro LED.

[0066] refer to Figure 4 In some embodiments, a pixel driving method for Micro LEDs is further provided, including:

[0067] S100: Input a drive signal to the gate of the MOS transistor in the drive circuit;

[0068] S200: Based on the driving signal, an inverted driving signal with a 180° phase difference from the driving signal is input to the substrate of the MOS transistor.

[0069] In some embodiments, step S100 above, inputting a drive signal to the gate of the MOS transistor in the drive circuit, further includes:

[0070] S101: Input a first driving signal to the gate of the first MOS transistor in the driving circuit, and input a second driving signal to the gate of the second MOS transistor in the driving circuit.

[0071] In some implementations, the first drive signal is an enable signal and the second drive signal is a control signal.

[0072] In some embodiments, in step S200 above, based on the driving signal, an inverted driving signal having a 180° phase difference with the driving signal is input to the substrate of the MOS transistor, further comprising:

[0073] S201: Based on the first driving signal, input a first inverted driving signal with a 180° phase difference from the first driving signal to the substrate of the first MOS transistor;

[0074] S202: Based on the second driving signal, input a second inverted driving signal with a 180° phase difference from the second driving signal to the substrate of the second MOS transistor.

[0075] In some embodiments, an inverter disposed between the gate and the substrate of the MOS transistor changes the signal phase of the gate, causing the substrate to have an opposite phase. Specifically, a first inverter 40 disposed between the substrate and the gate of the first MOS transistor creates a 180° phase difference between the substrate and the gate; a second inverter 60 disposed between the substrate and the gate of the second MOS transistor creates a 180° phase difference between the substrate and the gate.

[0076] In some embodiments, a voltage opposite to the gate can be input to the substrate of the first MOS transistor and a voltage opposite to the gate can be input to the substrate of the second MOS transistor by setting up circuits.

[0077] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A Micro LED driving circuit, characterized in that... include: A first MOS transistor, the gate of which is used to receive an enable signal; A first inverter, one end of which is electrically connected to the gate of the first MOS transistor, and the other end of which is electrically connected to the substrate of the first MOS transistor; A second MOS transistor, wherein the source of the first MOS transistor and the source of the second MOS transistor are electrically connected to the same voltage source, and the gate of the second MOS transistor is used to receive a control signal; as well as A current mirror is provided, wherein the drains of the first MOS transistor and the second MOS transistor are electrically connected to the current mirror, and the current mirror has an input interface for receiving an external current and an output interface for being electrically connected to an external light-emitting unit.

2. The Micro LED driving circuit according to claim 1, characterized in that, The current mirror mentioned above includes: A third MOSFET, wherein the source of the third MOSFET is electrically connected to the drain of the first MOSFET, the drain of the third MOSFET serves as the input interface, and the drain of the third MOSFET is electrically connected to the gate of the third MOSFET; and A fourth MOS transistor, the source of which is electrically connected to the drain of the second MOS transistor, the drain of which serves as the output interface, and the gate of the third MOS transistor is electrically connected to the gate of the fourth MOS transistor.

3. The Micro LED driving circuit according to claim 2, characterized in that, The gate of the first MOS transistor is electrically connected to the substrate of the third MOS transistor, and the gate of the second MOS transistor is electrically connected to the substrate of the fourth MOS transistor.

4. The Micro LED driving circuit according to claim 2, characterized in that, The first MOS transistor, the second MOS transistor, the third MOS transistor, and the fourth MOS transistor are PMOS transistors.

5. The Micro LED driving circuit according to any one of claims 1-4, characterized in that, It further includes a second inverter, one end of which is electrically connected to the gate of the second MOS transistor, and the other end of which is electrically connected to the substrate of the second MOS transistor.

6. The Micro LED driving circuit according to claim 5, characterized in that, The first inverter is used to reverse the phase of the signal at the gate of the first MOS transistor by 180°, and the second inverter is used to reverse the phase of the signal at the gate of the second MOS transistor by 180°.

7. A Micro LED driving system, characterized in that, include: Micro LED driving circuit according to any one of claims 1-6; as well as A light-emitting unit is electrically connected to an output interface of the Micro LED driving circuit.

8. The Micro LED driving system according to claim 7, characterized in that, The light-emitting unit is an LED, the output interface is electrically connected to the anode of the LED, and the cathode of the LED is grounded.

9. A Micro LED display panel, characterized in that, An array comprising two or more Micro LED driving systems as described in claim 7.

10. A pixel driving method for Micro LEDs, characterized in that, Includes the following steps: Input a driving signal to the gate of the first MOS transistor and the second MOS transistor of the Micro LED driving circuit according to claim 1; as well as Based on the driving signal, an inverse driving signal with a 180° phase difference from the driving signal is input to the substrates of the first MOS transistor and the second MOS transistor.

11. The pixel driving method for Micro LED according to claim 10, characterized in that, The step of inputting the driving signal to the gates of the first MOS transistor and the second MOS transistor in the MicroLED driving circuit further includes: A first driving signal is input to the gate of the first MOS transistor in the Micro LED driving circuit, and a second driving signal is input to the gate of the second MOS transistor in the Micro LED driving circuit. Furthermore, the step of inputting an inverted drive signal with a 180° phase difference from the drive signal to the substrates of the first MOS transistor and the second MOS transistor based on the drive signal further includes the following steps: Based on the first driving signal, a first inverted driving signal with a 180° phase difference from the first driving signal is input to the substrate of the first MOS transistor; and Based on the second driving signal, a second inverted driving signal with a 180° phase difference from the second driving signal is input to the substrate of the second MOS transistor.

12. The pixel driving method for Micro LED according to claim 11, characterized in that, Further steps include: The first inverter changes the signal phase at the gate of the first MOS transistor; and The signal phase of the gate of the second MOS transistor is changed by a second inverter disposed between the gate and the substrate of the second MOS transistor.

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