LED drive circuit and LED display screen

Abstract

The invention relates to the technical field of LED driving, and discloses an LED driving circuit and an LED display screen. The LED driving circuit comprises an LED driving chip used for receiving input brightness control data and outputting an input voltage and a control signal based on the input brightness control data; the inverting input end of the amplifier receives the input voltage output by the LED driving chip, the non-inverting input end of the amplifier is connected to the source electrode of the MOS tube, the output end of the amplifier is connected with the grid electrode of the MOS tube, and the drain electrode of the MOS tube is connected to the LED; the first end of the switching device is connected to the source electrode of the MOS tube, the second end of the switching device is connected to the connection point of the output end of the amplifier and the grid electrode of the MOS tube, and the third end of the switching device receives the control signal and is used for opening or closing the MOS tube according to the control signal to control the current flowing through the LED; and when the received input brightness control data is used for realizing the black screen, a connected control signal is output to the switching device, so that the switching device closes the MOS tube, and the current flowing through the LED is minimized. Therefore, the MOS tube can be controlled to be completely closed, and the current flowing through the LED is minimized.

Description

Technical Field

[0001] The present invention relates to the technical field of LED driving, and in particular to an LED driving circuit and an LED display screen. Background Art

[0002] Generally speaking, on an LED display screen that controls the RGB LED (Light Emitting Diode) drive at high speed according to the input of brightness control data, when the LED is turned off to achieve a black screen, the transistor driving the LED is not completely turned off. Due to the flow of a small amount of leakage current, it is difficult to achieve complete black. This phenomenon occurs especially in application scenarios where the LED drive current is large.

[0003] Therefore, how to perfectly achieve the black screen of the LED display has become a technical problem that needs to be solved. Summary of the invention

[0004] The embodiments of the present invention aim to provide an LED driving circuit and an LED display screen, which can solve the problem that a black screen cannot be achieved on the LED display screen due to leakage current in the existing transistors driving LEDs.

[0005] In order to solve the above technical problems, the first embodiment of the present invention provides an LED driving circuit, including an LED driving chip, an amplifier, a MOS tube and a switch device, wherein:

[0006] The LED driver chip is used to receive input brightness control data and output an input voltage and a control signal based on the input brightness control data;

[0007] The inverting input terminal of the amplifier receives the input voltage, the non-inverting input terminal of the amplifier is connected to the source of the MOS tube, the output terminal of the amplifier is connected to the gate of the MOS tube, and the drain of the MOS tube is connected to the LED;

[0008] The first end of the switch device is connected to the source of the MOS tube, the second end of the switch device is connected to the connection point of the output end of the amplifier and the gate of the MOS tube, and the third end of the switch device receives the control signal, and is used to turn on or off the MOS tube according to the control signal to control the current flowing through the LED;

[0009] When the LED driver chip receives input brightness control data that is brightness control data for realizing a black screen, it outputs a connected control signal to the switch device so that the switch device turns off the MOS tube to minimize the current flowing through the LED.

[0010] Optionally, the switch device includes a switch and a switch control unit, and the switch control unit is connected to the switch and is used to control the switch to be turned on or off according to the control signal.

[0011] Optionally, the switch includes a first end, a second end and a third end, the first end of the switch is connected to the source of the MOS tube as the first end of the switching device, the second end of the switch is connected to the connection point between the output end of the amplifier and the gate of the MOS tube as the second end of the switching device, and the second end of the switch is connected to the switch control unit.

[0012] Optionally, the switch control unit includes a first end and a second end, the first end of the switch control unit is connected to the LED driver chip as the third end of the switch device to receive the control signal, and the second end of the switch control unit is connected to the third end of the switch.

[0013] Optionally, when the LED driver chip receives input brightness control data that is brightness control data for realizing a black screen, the LED driver chip outputs a connected control signal to the switch control unit. After receiving the connected control signal, the switch control unit controls the switch to close, so that the source of the MOS tube is short-circuited to the gate of the MOS tube and the MOS tube is directly closed, thereby minimizing the current flowing through the LED.

[0014] Optionally, the gate of the MOS tube is connected to the output end of the amplifier, the drain of the MOS tube is connected to the LED, the source of the MOS tube is connected to a resistor and then grounded, and the source of the MOS tube is connected to the same-direction input end of the amplifier.

[0015] Optionally, the amplifier is a unity gain amplifier.

[0016] Correspondingly, the second embodiment of the present invention provides an LED display screen, comprising an LED and the LED driving circuit described in the first embodiment of the present invention, wherein the LED driving circuit is connected to the LED and is used to control the current flowing through the LED.

[0017] Compared with the prior art, the present invention provides an LED driving circuit and an LED display screen, wherein the LED driving circuit comprises an LED driving chip, an amplifier, a MOS tube and a switch device, wherein the LED driving chip is used to receive input brightness control data and output an input voltage and a control signal based on the input brightness control data; the amplifier is connected to the LED driving chip, the reverse input end of the amplifier receives the input voltage output by the LED driving chip, the non-inverting input end of the amplifier is connected to the source of the MOS tube, the output end of the amplifier is connected to the gate of the MOS tube, and the drain of the MOS tube is connected to the LED; the first end of the switch device is connected to the source of the MOS tube, the second end of the switch device is connected to the connection point between the output end of the amplifier and the gate of the MOS tube, and the third end of the switch device receives a control signal output by the LED driving chip, and is used to turn on or off the MOS tube according to the input control signal to control the current flowing through the LED; when the LED driving chip receives the input brightness control data which is brightness control data for realizing a black screen, the output connected control signal is given to the switch device so that the switch device turns off the MOS tube to minimize the current flowing through the LED. Thus, by setting a switch device in the LED driving circuit, the MOS tube driving the LED can be controlled to be completely closed or opened at high speed based on the input of brightness control data, with a fast response speed to control the current flowing through the LED, and when the input brightness control data is brightness control data for realizing a black screen, the MOS tube is controlled to be quickly and completely closed to minimize the leakage current, minimize the current flowing through the LED, improve the color reproducibility of the LED, improve the brightness ratio of the high-efficiency LED, and the LED driving circuit has a simple structure, is easy to realize, and has a low cost. Thus, the problem that the black screen of the LED display cannot be realized due to the leakage current of the existing transistor driving the LED can be solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] One or more embodiments are exemplarily described by pictures in the corresponding drawings, and these exemplified descriptions do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0019] Figure 1 It is a structural schematic diagram of an LED driving circuit in the prior art;

[0020] Figure 2 It is a structural schematic diagram of an LED driving circuit provided by the present invention;

[0021] Figure 3 It is a schematic diagram of simulation results of an LED driving circuit in the prior art;

[0022] Figure 4 It is a schematic diagram of simulation results of an LED driving circuit provided by the present invention;

[0023] Figure 5 The present invention provides a schematic structural diagram of an LED display screen. DETAILED DESCRIPTION

[0024] In order to facilitate the understanding of the present invention, the present invention is described in more detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that when an element is described as "fixed to" another element, it can be directly on another element or there can be one or more centered elements therebetween. When an element is described as "connected" to another element, it can be directly connected to another element or there can be one or more centered elements therebetween. The orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "bottom" etc. used in this specification is based on the orientation or positional relationship shown in the accompanying drawings, only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0025] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in this specification and in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

[0026] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0027] Generally speaking, on an LED display screen that controls the RGB LED (Light Emitting Diode) drive at high speed according to the input of brightness control data, when the LED is turned off to achieve a black screen, the transistor driving the LED is not completely turned off, and it is difficult to achieve complete black due to the flow of a small amount of leakage current. This phenomenon occurs especially in application scenarios where the LED drive current is large. In this application scenario, since the current of the driving transistor is large, the current charging the gate of the driving transistor cannot be completely turned off. In addition, due to the characteristics of the LED display, color must be achieved at high speed, so the switching speed and closing speed of the driving transistor must be achieved in a very short time.

[0028] Figure 1 FIG. 1 is a schematic diagram of the output end of an existing LED driving circuit. Figure 1In the embodiment, the LED driver chip 4 generates the voltage suitable for the maximum and minimum current of LED1 as the input voltage Vin of the output end of the LED driver circuit according to the input brightness control data L_Data. When the input voltage Vin is applied to the negative input end of the amplifier 2, the voltage of the connection point PointA of the same-direction input end of the amplifier 2 and the source S of the NMOS tube 3 is the same as the input voltage Vin through the circuit operation, and the LED driving current is determined as the voltage of the connection point PointB of the output end of the amplifier 2 and the gate G of the NMOS tube 3 / the resistance value of the resistor R1. At this time, the NMOS tube 3 is turned on, so that the current flows through the LED1, and the voltage applied to the connection point PointA is the threshold voltage (Vthreshold) of the NMOS tube 3.

[0029] The smaller the current flowing through LED1, the more LED1 is completely turned off, and the black screen can be perfectly realized. Therefore, when realizing a black screen, the current flowing through LED1 needs to be minimized. For example, when the LED driver chip 4 receives black data as the input of the brightness control data L_Data, it can Figure 1 0V is applied to the input voltage Vin of the LED driving circuit. When 0V is applied to the input voltage Vin, the voltage of the connection point PointA also becomes 0V, and the threshold voltage of the NMOS tube 3 is applied to the connection point PointB. In this case, although the current flowing through LED1 is minimized, the NMOS tube 3 is still in the working state, and the NMOS tube 3 is not completely turned off. There is a small amount of leakage current flowing, and it is difficult to achieve complete black.

[0030] Therefore, how to perfectly achieve the black screen of the LED display has become a technical problem that needs to be solved.

[0031] To this end, the present invention provides an LED driving circuit, which can control the MOS tube driving the LED to be completely turned off or on at high speed based on the input of brightness control data by setting a switch device in the LED driving circuit, and has a fast response speed to control the current flowing through the LED, and when the input brightness control data is brightness control data for realizing a black screen, the MOS tube is controlled to be quickly and completely turned off, so as to minimize the leakage current, minimize the current flowing through the LED, improve the color reproducibility of the LED, and improve the brightness ratio of the high-efficiency LED, and the LED driving circuit has a simple structure, is easy to realize, and has a low cost. Thus, the problem that the black screen of the LED display cannot be realized due to the leakage current of the existing transistor driving the LED can be solved.

[0032] In order to facilitate understanding of the above inventive concept of the present invention, the above inventive concept of the present invention is described in more detail below in conjunction with the accompanying drawings and specific embodiments.

[0033] In one embodiment, Figure 2 As shown, the present invention provides an LED driving circuit 20, including an LED driving chip 21, an amplifier 22, a MOS tube 23 and a switch device 24, wherein:

[0034] The LED driving chip 21 is used to receive input brightness control data L_Data, and output an input voltage Vin and a control signal Kin based on the input brightness control data L_Data;

[0035] The amplifier 22 is connected to the LED driver chip 21, the inverting input terminal of the amplifier 22 receives the input voltage Vin output by the LED driver chip 21, the non-inverting input terminal of the amplifier 22 is connected to the source S of the MOS tube 23, the output terminal of the amplifier 22 is connected to the gate G of the MOS tube 23, and the drain D of the MOS tube 23 is connected to the LED 10;

[0036] The first end of the switch device 24 is connected to the source S of the MOS tube 23, the second end of the switch device 24 is connected to the connection point between the output end of the amplifier 22 and the gate G of the MOS tube 23, and the third end of the switch device 24 receives the control signal Ki n output by the LED driver chip 21, and is used to turn on or off the MOS tube 23 according to the input control signal Ki n, so as to control the current flowing through the LED 10;

[0037] When the LED driver chip 21 receives input brightness control data L_Data that is brightness control data for realizing a black screen, it outputs a connected control signal to the switch device 24 so that the switch device 20 turns off the MOS tube 23 to minimize the current flowing through the LED 10 .

[0038] In this embodiment, an LED driving circuit is provided, including an LED driving chip, an amplifier, a MOS tube and a switching device, wherein the LED driving chip is used to receive input brightness control data and output an input voltage and a control signal based on the input brightness control data; the amplifier is connected to the LED driving chip, the reverse input end of the amplifier receives the input voltage output by the LED driving chip, the non-inverting input end of the amplifier is connected to the source of the MOS tube, the output end of the amplifier is connected to the gate of the MOS tube, and the drain of the MOS tube is connected to the LED; the first end of the switching device is connected to the source of the MOS tube, the second end of the switching device is connected to the connection point between the output end of the amplifier and the gate of the MOS tube, and the third end of the switching device receives the control signal output by the LED driving chip, and is used to turn on or off the MOS tube according to the input control signal to control the current flowing through the LED; when the LED driving chip receives the input brightness control data for realizing the brightness control data of the black screen, the output connected control signal is given to the switching device so that the switching device turns off the MOS tube to minimize the current flowing through the LED. Thus, by setting a switch device in the LED driving circuit, the MOS tube driving the LED can be controlled to be completely closed or opened at high speed based on the input of brightness control data, with a fast response speed to control the current flowing through the LED, and when the input brightness control data is brightness control data for realizing a black screen, the MOS tube is controlled to be quickly and completely closed to minimize the leakage current, minimize the current flowing through the LED, improve the color reproducibility of the LED, improve the brightness ratio of the high-efficiency LED, and the LED driving circuit has a simple structure, is easy to realize, and has a low cost. Thus, the problem that the black screen of the LED display cannot be realized due to the leakage current of the existing transistor driving the LED can be solved.

[0039] In one embodiment, the LED driving chip 21 is used to receive input brightness control data L_Data, and output an input voltage Vin and a control signal Ki n based on the input brightness control data L_Data.

[0040] Specifically, the LED driving chip 21 receives the input brightness control data L_Data, and generates an input voltage Vin and a control signal Kin suitable for the maximum current and the minimum current of the LED 10 based on the received brightness control data L_Data.

[0041] In one embodiment, the reverse input terminal of the amplifier 22 is connected to the LED driver chip 21 to receive the input voltage Vin output by the LED driver chip 21, the non-inverting input terminal of the amplifier 22 is connected to the source S of the MOS tube 23, and the output terminal of the amplifier 22 is connected to the gate G of the MOS tube 23.

[0042] Specifically, Figure 2As shown, the amplifier 22 is connected to the LED driver chip 21, and the input voltage Vin is applied to the reverse input terminal (-) of the amplifier 22 based on the input brightness control data L_Data, and the same-direction input terminal (+) of the amplifier 22 is connected to the source S of the MOS tube 23. The connection point between the same-direction input terminal (+) of the amplifier 22 and the source S of the MOS tube 23 is the first point PointA, that is, the same-direction input terminal (+) of the amplifier 22 is connected to the first point PointA, and the output terminal of the amplifier 22 is connected to the gate G of the MOS tube 23. The connection point between the output terminal of the amplifier 22 and the gate G of the MOS tube 23 is the second point PointB.

[0043] For example, the reverse input terminal (-) of the amplifier 22 can be connected to the output terminal of the LED driver chip 21. The LED driver chip 21 generates an input voltage Vin suitable for the maximum current and minimum current of the LED 10 according to the received brightness control data L_Data, and applies it to the reverse input terminal (-) of the amplifier 22.

[0044] For example, the amplifier 22 may be a unity gain amplifier.

[0045] In one embodiment, Figure 2 As shown, the gate G of the MOS tube 23 is connected to the output end of the amplifier 22, the drain D of the MOS tube 23 is connected to the LED 10, the source S of the MOS tube 23 is connected to a resistor R2 and then grounded, the source S of the MOS tube 23 is connected to the same-direction input end (+) of the amplifier 22, and the connection point between the source S of the MOS tube 23 and the same-direction input end (+) of the amplifier 22 is the first point PointA.

[0046] For example, the MOS transistor 23 may be an NMOS transistor.

[0047] In one embodiment, the LED driving circuit 20 includes a switching device 24, a first end of the switching device 24 is connected to the source S of the MOS tube 23, a second end of the switching device 24 is connected to the connection point between the output end of the amplifier 22 and the gate G of the MOS tube 23, and a third end of the switching device 24 receives a control signal Kin output by the LED driving chip 21, and is used to turn on or off the MOS tube 23 according to the input control signal Kin, thereby controlling the current flowing through the LED 10.

[0048] Specifically, Figure 2As shown, the switch device 24 is connected to the MOS tube 23 and the LED driver chip 21 respectively, the first end of the switch device 24 is connected to the source S of the MOS tube 23, and the second end of the switch device 24 is connected to the connection point between the output end of the amplifier 22 and the gate G of the MOS tube 23, that is, the first end of the switch device 24 is connected to the first point PointA, the second end of the switch device 24 is connected to the second point PointB, and the third end of the switch device 24 is connected to the LED driver chip 21 to receive the control signal Kin output by the LED driver chip 21.

[0049] like Figure 2 As shown, the switch device 24 includes a switch 241 and a switch control unit 242, and the switch control unit 242 is connected to the switch 241, and is used to control the switch 241 to be turned on or off according to the received control signal Kin. Specifically, the switch 241 includes a first end, a second end, and a third end. The first end of the switch 241 is connected to the source S of the MOS tube 23 as the first end of the switch device 24 (that is, the first end of the switch device 24 is connected to the first point PointA), and the second end of the switch 241 is connected to the connection point of the output end of the amplifier 22 and the gate G of the MOS tube 23 as the second end of the switch device 24 (that is, the second end of the switch 241 is connected to the second point PointB).

[0050] The switch control unit 242 includes a first end and a second end. The first end of the switch control unit 242 is connected to the LED driver chip 21 as the third end of the switch device 24, and receives the control signal Kin output by the LED driver chip 21. The second end of the switch control unit 242 is connected to the third end of the switch 241, and is used to control the switch 241 to open or close according to the received control signal Kin.

[0051] When the brightness control data received by the LED driver chip 21 is not the brightness control data for making the LED 10 realize a black screen, the LED driver chip 21 outputs a disconnected control signal Kin to the switch control unit 242. After the switch control unit 242 receives the disconnected control signal Kin, it controls the switch 241 to open, so that the connection between the first point PointA and the second point PointB is disconnected, so that the gate voltage of the MOS tube 23 is directly applied with the voltage output by the output end of the amplifier 22, thereby directly turning on the MOS tube 23, so that current flows through the LED 10 connected to the drain D of the MOS tube 23.

[0052] When the brightness control data received by the LED driver chip 21 is brightness control data for making the LED 10 realize a black screen, the LED driver chip 21 outputs a connected control signal Kin to the switch control unit 242. After the switch control unit 242 receives the connected control signal Kin, it controls the switch 241 to be closed, so that the first point PointA and the second point PointB are short-circuited, so that the gate voltage of the MOS tube 23 is directly applied with 0V, thereby directly turning off the MOS tube 23, minimizing the leakage current, and further minimizing the current flowing through the LED 10 connected to the drain D of the MOS tube 23.

[0053] For example, when the brightness control data received by the LED driver chip 21 is 8-bit brightness control data for realizing a black screen (for example, the black brightness control data is 0000000000), the LED driver chip 21 outputs the connected control signal Kin to the switch control unit 242. After the switch control unit 242 receives the connected control signal Kin, it can close the switch 241 to short-circuit the connection between the first point PointA and the second point PointB.

[0054] In other words, in order to realize the black screen, when the MOS tube 23 driving the LED 10 is completely turned off (that is, when the brightness control data is all 0), the gate switch 241 of the MOS tube 23 can be directly bypassed (Bypass), so that the gate voltage of the MOS tube 23 is directly applied to 0V, thereby directly turning off the MOS tube 23.

[0055] Therefore, when the brightness control data of the LED 10 for realizing a black screen is input, the switch control unit 242 turns off the switch 241, thereby short-circuiting the first point PointA and the second point PointB, thereby reaching the same voltage of 0 V. That is, it makes the gate voltage of the MOS tube 23 0 V and immediately turns off the MOS tube 23 completely, thereby further minimizing the current flowing through the LED 10.

[0056] like Figure 3 and Figure 4 As shown, Figure 3 This is a schematic diagram of the simulation results of the existing LED drive circuit. Figure 4 Schematic diagram of simulation results of an LED driving circuit according to an embodiment of the present invention.

[0057] exist Figure 3 In the conventional LED driving circuit, in the black data interval, the voltage at the second point Point B is approximately 0.34 V, and the current flowing through the LED 10 is approximately 14 nA.

[0058] And in Figure 4In the LED driving circuit according to the embodiment of the present invention, in the black data (BlackData) interval, the voltage of the second point PointB is almost 0V, and the current flowing through the LED 10 is about 1nA. That is, compared with the existing LED driving circuit, the current flowing through the LED 10 in the black data interval according to the LED driving circuit of the embodiment of the present invention is improved to about 1 / 14. Thus, a high efficiency brightness ratio can be achieved compared with the existing LED driving circuit.

[0059] Therefore, according to the LED driving circuit of the embodiment of the present invention, since the RGBLED10 can be completely turned off, high color reproducibility can be ensured, and the switch 241 is connected to the gate G of the MOS tube 23 for control, so the response speed is very fast and can be configured as a very simple circuit.

[0060] Based on the same concept, in one embodiment, Figure 5 As shown, the present invention further provides an LED display screen 100 , comprising an LED 10 and an LED driving circuit 20 as described in any of the above embodiments, wherein the LED driving circuit 20 is connected to the LED 10 and is used to control the current flowing through the LED 10 .

[0061] In this embodiment, the LED driving circuit 20 is consistent with the LED driving circuit 20 described in any of the above embodiments. The specific structure and function can refer to the LED driving circuit 20 described in any of the above embodiments, which will not be repeated here.

[0062] In one embodiment, a first end of the LED 10 is connected to the drain D of the MOS tube 23 , and a second end of the LED 10 is connected to a reference power source Power.

[0063] For example, the LED 10 is an RGB LED and can reproduce RGB colors.

[0064] In this embodiment, an LED display screen is provided, comprising an LED and an LED driving circuit, wherein the LED driving circuit is connected to the LED and used to control the current flowing through the LED. The LED driving circuit comprises an LED driving chip, an amplifier, a MOS tube and a switch device, wherein the LED driving chip is used to receive input brightness control data and output an input voltage and a control signal based on the input brightness control data; the amplifier is connected to the LED driving chip, the reverse input end of the amplifier receives the input voltage output by the LED driving chip, the non-inverting input end of the amplifier is connected to the source of the MOS tube, the output end of the amplifier is connected to the gate of the MOS tube, and the drain of the MOS tube is connected to the LED; the first end of the switch device is connected to the source of the MOS tube, the second end of the switch device is connected to the connection point between the output end of the amplifier and the gate of the MOS tube, and the third end of the switch device receives the control signal output by the LED driving chip, and is used to turn on or off the MOS tube according to the input control signal to control the current flowing through the LED; when the LED driving chip receives the input brightness control data for realizing the brightness control data of the black screen, the connected control signal is output to the switch device, so that the switch device turns off the MOS tube to minimize the current flowing through the LED. Thus, by setting a switch device in the LED driving circuit, the MOS tube driving the LED can be controlled to be completely closed or opened at high speed based on the input of brightness control data, with a fast response speed to control the current flowing through the LED, and when the input brightness control data is brightness control data for realizing a black screen, the MOS tube is controlled to be quickly and completely closed to minimize the leakage current, minimize the current flowing through the LED, improve the color reproducibility of the LED, improve the brightness ratio of the high-efficiency LED, and the LED driving circuit has a simple structure, is easy to realize, and has a low cost. Thus, the problem that the black screen of the LED display cannot be realized due to the leakage current of the existing transistor driving the LED can be solved.

[0065] It should be noted that the above-mentioned LED display screen embodiment and the above-mentioned LED driving circuit embodiment belong to the same concept, and the specific implementation process is detailed in the LED driving circuit embodiment, and the technical features in the LED driving circuit embodiment are correspondingly applicable in the above-mentioned LED display screen embodiment, which will not be repeated here.

[0066] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0067] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Under the concept of the present invention, the technical features in the above embodiments or different embodiments may also be combined, the steps may be implemented in any order, and there are many other changes in different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity. Although the present invention has been described in detail with reference to the above embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the above embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An LED driving circuit, characterized in that: It includes LED driver chip, amplifier, MOS tube and switch device, among which: The LED driver chip is used to receive input brightness control data and output an input voltage and a control signal based on the input brightness control data; The inverting input terminal of the amplifier receives the input voltage, the non-inverting input terminal of the amplifier is connected to the source of the MOS tube, the output terminal of the amplifier is connected to the gate of the MOS tube, and the drain of the MOS tube is connected to the LED; The first end of the switch device is connected to the source of the MOS tube, the second end of the switch device is connected to the connection point of the output end of the amplifier and the gate of the MOS tube, and the third end of the switch device receives the control signal, and is used to turn on or off the MOS tube according to the control signal to control the current flowing through the LED; When the LED driver chip receives input brightness control data that is brightness control data for realizing a black screen, it outputs a connected control signal to the switch device so that the switch device turns off the MOS tube to minimize the current flowing through the LED.

2. The LED driving circuit according to claim 1, characterized in that: The switch device includes a switch and a switch control unit. The switch control unit is connected to the switch and is used to control the switch to be turned on or off according to the control signal.

3. The LED driving circuit according to claim 2, characterized in that: The switch includes a first end, a second end and a third end. The first end of the switch is connected to the source of the MOS tube as the first end of the switching device, the second end of the switch is connected to the connection point of the output end of the amplifier and the gate of the MOS tube as the second end of the switching device, and the second end of the switch is connected to the switch control unit.

4. The LED driving circuit according to claim 3, characterized in that: The switch control unit includes a first end and a second end. The first end of the switch control unit is connected to the LED driver chip as the third end of the switch device to receive the control signal. The second end of the switch control unit is connected to the third end of the switch.

5. The LED driving circuit according to claim 4, characterized in that: When the LED driver chip receives input brightness control data that is brightness control data for realizing a black screen, the LED driver chip outputs a connected control signal to the switch control unit. After receiving the connected control signal, the switch control unit controls the switch to be closed, so that the source of the MOS tube is short-circuited with the gate of the MOS tube and the MOS tube is directly closed, thereby minimizing the current flowing through the LED.

6. The LED driving circuit according to claim 1, characterized in that: The gate of the MOS tube is connected to the output end of the amplifier, the drain of the MOS tube is connected to the LED, the source of the MOS tube is connected to a resistor and then grounded, and the source of the MOS tube is connected to the same-direction input end of the amplifier.

7. The LED driving circuit according to claim 1, characterized in that: The amplifier is a unity gain amplifier.

8. An LED display screen, characterized in that: The invention comprises an LED and the LED driving circuit according to any one of claims 1 to 7, wherein the LED driving circuit is connected to the LED and is used to control the current flowing through the LED.

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