Current sampling method, multi-stage dimming circuit and lighting equipment

Abstract

A current sampling method, a multi-stage dimming circuit and a lighting device, the current sampling method is applied to a multi-stage sampling circuit, the multi-stage sampling circuit is used for sampling a current of a first input end and amplifying the current at a first multiplying power to obtain a first sampling current; and the sampling module is used for sampling the current of the second input end and amplifying the current at a second multiplying power to obtain a second sampling current. The current sampling method comprises the step of obtaining a working current according to a first sampling current and a second sampling current under the condition that an expected current is not smaller than a first current threshold and smaller than a second current threshold. Under the condition that the expected current is not smaller than the first current threshold value and smaller than the second current threshold value, the working current is obtained according to the first sampling current and the second sampling current, so that the change of the obtained working current is smoother when the sampling channel is switched, and the working current is prevented from shaking.

Description

Technical Field

[0001] This application belongs to the field of lighting technology, and particularly relates to a current sampling method, a multi-stage dimming circuit, and a lighting device. Background Art

[0002] Currently, traditional light-emitting diode (LED) drivers usually adopt single-stage current sampling technology to adjust the brightness through Pulse Width Modulation (PWM) or analog voltage. However, single-stage sampling has problems such as insufficient dynamic range for high-current dimming and low precision for low-current dimming, making it difficult to achieve ultra-high-resolution dimming. It is difficult to balance the requirements of high-current constant-current drive and low-current fine dimming, resulting in limited application scenarios and high hardware requirements. Summary of the Invention

[0003] The purpose of this application is to provide a current sampling method, a multi-stage dimming circuit, and a lighting device, aiming to solve the problem that traditional lighting devices have difficulty in balancing high-resolution dimming and high-precision dimming.

[0004] In a first aspect of an embodiment of this application, a current sampling method is provided, which is applied to a multi-stage sampling circuit. The multi-stage sampling circuit is used to sample the working current of a light-emitting module. The first input terminal and the second input terminal of the multi-stage sampling circuit are both connected to the output terminal of the light-emitting module. The multi-stage sampling circuit is used to sample the current at the first input terminal and amplify it by a first magnification to obtain a first sampling current, and to sample the current at the second input terminal and amplify it by a second magnification to obtain a second sampling current. The first magnification is greater than the second magnification, and the sampling accuracy of the first sampling current is greater than that of the second sampling current. The current sampling method includes: when the desired current is less than a first current threshold, obtaining the working current according to the first sampling current; when the desired current is not less than a second current threshold, obtaining the working current according to the second sampling current; the second current threshold is greater than the first current threshold; when the desired current is not less than the first current threshold and less than the second current threshold, obtaining the working current according to the first sampling current and the second sampling current.

[0005] In one embodiment, obtaining the working current according to the first sampled current and the second sampled current includes: obtaining a first proportionality coefficient and a second proportionality coefficient according to the desired current, the first current threshold, and the second current threshold; wherein, the first proportionality coefficient is equal to the difference between the second current threshold and the desired current divided by the difference between the second current threshold and the first current threshold, and the sum of the first proportionality coefficient and the second proportionality coefficient is equal to 1; multiplying the first sampled current by the first proportionality coefficient and adding the product of the second sampled current and the second proportionality coefficient to obtain the working current.

[0006] In one embodiment, the multi-stage sampling circuit includes: a first sampling switch module, a second sampling switch module, and a sampling module. The first sampling switch module is connected between the light-emitting module and the first input terminal of the sampling module; the second sampling switch module is connected between the light-emitting module and the second input terminal of the sampling module; the sampling module is configured to sample the current at the first input terminal and amplify it at a first magnification to obtain a first sampled current, or to sample the current at the second input terminal and amplify it at a second magnification to obtain a second sampled current. The first magnification is greater than the second magnification, and the sampling accuracy of the first sampled current is greater than that of the second sampled current. The current sampling method further includes: when the desired current is less than the first current threshold, controlling the first sampling switch module to conduct and the second sampling switch module to turn off; when the desired current is not less than the second current threshold, controlling the first sampling switch module to turn off and the second sampling switch module to conduct; when the desired current is not less than the first current threshold and less than the second current threshold, controlling the first sampling switch module and the second sampling switch module to conduct simultaneously.

[0007] In one embodiment, the first current threshold is greater than the minimum value of the ideal input current at the second input terminal of the sampling module, and the second current threshold is less than the maximum value of the ideal input current at the first input terminal of the sampling module.

[0008] The second aspect of the embodiments of the present application provides a multi-level dimming circuit, including a multi-level sampling circuit and a control module; the multi-level sampling circuit is used to sample the working current of the light-emitting module, and the first input end and the second input end of the multi-level sampling circuit are both connected to the output end of the light-emitting module; the multi-level sampling circuit is used to sample the current at the first input end and amplify it by a first magnification to obtain a first sampled current, or to sample the current at the second input end and amplify it by a second magnification to obtain a second sampled current, where the first magnification is greater than the second magnification; the control module is connected to the multi-level sampling circuit; the control module is used to obtain the working current according to the first sampled current when the desired current is less than the first current threshold; to obtain the working current according to the second sampled current when the desired current is not less than the second current threshold; the second current threshold is greater than the first current threshold; and to obtain the working current according to the first sampled current and the second sampled current when the desired current is not less than the first current threshold and less than the second current threshold.

[0009] In one embodiment, the multi-level sampling circuit includes: a first sampling switch module, a second sampling switch module, and a sampling module. The first sampling switch module is connected between the light-emitting module and the first input end of the sampling module; the second sampling switch module is connected between the light-emitting module and the second input end of the sampling module; the sampling module is used to sample the current at the first input end and amplify it by a first magnification to obtain a first sampled current, or to sample the current at the second input end and amplify it by a second magnification to obtain a second sampled current, where the first magnification is greater than the second magnification; the control module is respectively connected to the first sampling switch module, the second sampling switch module, and the sampling module; the control module is further used to control the first sampling switch module to conduct and the second sampling switch module to turn off when the desired current is less than the first current threshold; to control the first sampling switch module to turn off and the second sampling switch module to conduct when the desired current is not less than the second current threshold; and to control the first sampling switch module to turn off and the second sampling switch module to conduct simultaneously when the desired current is not less than the first current threshold and less than the second current threshold.

[0010] In one embodiment, the control module includes a control unit and a driving unit; the control unit is connected to the sampling module, and the control unit is configured to: obtain the working current of the light-emitting module according to the first sampled current or the second sampled current; the driving unit is respectively connected to the first sampling switch module, the second sampling switch module and the control unit, and the control unit is further configured to control the driving unit to transmit a first control signal and a second control signal to the first sampling switch module and the second sampling switch module respectively, the first control signal is used to control the first sampling switch module to conduct, and the second control signal is used to control the second sampling switch module to conduct.

[0011] In one embodiment, the multi-stage dimming circuit further includes a power module, the power module is respectively connected to the light-emitting module and the control module; the control module is further configured to obtain the working current of the light-emitting module according to the first sampled current and the second sampled current, and adjust the output power of the power module according to the working current and the desired current.

[0012] A third aspect of the embodiments of the present application provides an illumination device, including a light-emitting module and the multi-stage dimming circuit as described above, the multi-stage dimming circuit is connected to the light-emitting module for adjusting the working current of the light-emitting module.

[0013] In one embodiment, the illumination device further includes a host computer, the host computer is connected to the multi-stage dimming circuit, and the host computer is configured to provide a control signal corresponding to the desired current to the multi-stage dimming circuit.

[0014] The beneficial effects of the embodiments of the present application compared with the prior art are as follows: Since the first magnification is greater than the second magnification, the multi-stage sampling circuit can sample when the working current of the light-emitting module is a small current to perform fine dimming according to the first sampled current, and can also sample when the working current of the light-emitting module is a large current to take into account large-current dimming according to the second sampled current, increasing the dynamic range during dimming, so that high-precision dimming can be achieved according to the first sampled current and the second sampled current while taking into account high-resolution dimming.

[0015] By obtaining the working current according to the first sampled current and the second sampled current when the desired current is not less than the first current threshold and less than the second current threshold, it can be used to make the change of the obtained working current smoother when switching the sampling channel, thereby avoiding the situation of jitter of the working current and flicker of the light-emitting module. Description of the Drawings

[0016] Figure 1 It is a flowchart of a current sampling method provided by an embodiment of the present application;

[0017] Figure 2 Schematic diagram of the connection between the multi - level sampling circuit and the light - emitting module provided by an embodiment of the present application;

[0018] Figure 3 Schematic diagram of the principle of the multi - level sampling circuit provided by an embodiment of the present application;

[0019] Figure 4 Another flowchart of the current sampling method provided by an embodiment of the present application;

[0020] Figure 5 Schematic diagram of the principle of the multi - level dimming circuit provided by an embodiment of the present application;

[0021] Figure 6 Schematic diagram of the lighting device provided by an embodiment of the present application. Detailed implementation manners

[0022] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0023] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0024] It should be understood that the orientation or positional relationship indicated by the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application 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 should not be construed as a limitation of the present application.

[0025] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, "a plurality" means two or more unless otherwise specifically defined.

[0026] Figure 1The flowchart of the current sampling method provided by an embodiment of the present application is shown. For the convenience of description, only the parts related to this embodiment are shown and are described in detail as follows:

[0027] A current sampling method is applied to a multi-stage sampling circuit 10 as shown in Figure 2 Figure. The multi-stage sampling circuit 10 is used to sample the working current of the light-emitting module 20. The first input terminal and the second input terminal of the multi-stage sampling circuit 10 are both connected to the output terminal of the light-emitting module 20. Specifically, the light-emitting module 20 may include an LED lamp group.

[0028] The multi-stage sampling circuit 10 is used to sample the current at the first input terminal and amplify it at a first magnification to obtain a first sampled current, and is also used to sample the current at the second input terminal and amplify it at a second magnification to obtain a second sampled current. The sampling accuracy of the first sampled current is greater than that of the second sampled current, and the first magnification is greater than the second magnification.

[0029] The current sampling method includes step S100 to step S300.

[0030] Step S100: When the expected current is less than the first current threshold, obtain the working current according to the first sampled current.

[0031] Step S200: When the expected current is not less than the second current threshold, obtain the working current according to the second sampled current; the second current threshold is greater than the first current threshold.

[0032] Step S300: When the expected current is not less than the first current threshold and less than the second current threshold, obtain the working current according to the first sampled current and the second sampled current.

[0033] Since the first magnification is greater than the second magnification, the multi-stage sampling circuit 10 can not only sample when the working current of the light-emitting module is a small current to perform fine dimming according to the first sampled current, but also sample when the working current of the light-emitting module is a large current to take into account large-current dimming according to the second sampled current, increasing the dynamic range during dimming. Thus, it is possible to achieve high-precision dimming according to the first sampled current and the second sampled current while taking into account high-resolution dimming.

[0034] It should be noted that the multi-stage sampling circuit 10 samples and amplifies the current at the first input terminal and the current at the first input terminal at different magnification factors, respectively, to form two sampling channels, which can sample the working current of small current and the working current of large current, respectively. When the sampling accuracies of the two sampling channels are different, if the same working current is sampled, the sampled current obtained by the sampling channel with lower sampling accuracy is usually different from the sampled current obtained by the sampling channel with higher sampling accuracy. Therefore, when switching the sampling channels, the obtained working current will have a certain jump, and the jump of the working current obtained by sampling will affect the dimming of the light-emitting module 20, resulting in the light-emitting module 20 flickering.

[0035] Step S300 can be used to make the change of the obtained working current smoother when switching the sampling channels, thereby avoiding the jitter of the working current and the flickering of the light-emitting module 20.

[0036] In one embodiment, step S300 specifically includes: when the desired current is not less than the first current threshold and less than the second current threshold, obtaining a first proportional coefficient and a second proportional coefficient according to the desired current, the first current threshold, and the second current threshold; wherein, the first proportional coefficient is equal to the difference between the second current threshold and the desired current divided by the difference between the second current threshold and the first current threshold, and the sum of the first proportional coefficient and the second proportional coefficient is equal to 1; multiplying the first sampled current by the first proportional coefficient and adding the product of the second sampled current and the second proportional coefficient to obtain the working current.

[0037] In summary, in step S300, the calculation formula of the working current is:

[0038] Working current = second sampled current * [1 - (second current threshold - desired current) / (second current threshold - first current threshold)] + first sampled current * (second current threshold - desired current) / (second current threshold - first current threshold).

[0039] It can be understood that when the desired current linearly increases from the first current threshold to the second current threshold, the first proportional coefficient monotonically decreases from 1 to 0, and the second proportional coefficient monotonically increases from 0 to 1. Therefore, the working current can smoothly change from the first sampled current to the second sampled current.

[0040] When the desired current linearly decreases from the second current threshold to the first current threshold, the second proportional coefficient monotonically decreases from 1 to 0, and the first proportional coefficient monotonically increases from 0 to 1. Therefore, the working current can smoothly change from the second sampled current to the first sampled current.

[0041] Among them, the first current threshold and the second current threshold can be set according to actual requirements. The smaller the difference between the first current threshold and the second current threshold, the greater the fluctuation of the working current and the faster the sampling switching speed. The greater the difference between the first current threshold and the second current threshold, the smaller the fluctuation of the working current and the slower the sampling switching speed.

[0042] Exemplarily, in one embodiment, the second current threshold can be 500 mA, and the first current threshold can be slightly less than 500 mA. For example, it can be 490 mA.

[0043] In one embodiment, as Figure 3 shown, the multi-stage sampling circuit 10 includes: a first sampling switch module 100, a second sampling switch module 200, and a sampling module 300. The first sampling switch module 100 is connected between the light-emitting module 20 and the first input terminal of the sampling module 300. The second sampling switch module 200 is connected between the light-emitting module 20 and the second input terminal of the sampling module 300.

[0044] The sampling module 300 is configured to sample the current at the first input terminal and amplify it at a first magnification to obtain a first sampling current, or to sample the current at the second input terminal and amplify it at a second magnification to obtain a second sampling current. The sampling accuracy of the first sampling current is greater than that of the second sampling current, and the first magnification is greater than the second magnification.

[0045] As Figure 4 shown, the current sampling method further includes steps S400 to S600.

[0046] Step S400: When the desired current is less than the first current threshold, control the first sampling switch module 100 to conduct and the second sampling switch module 200 to turn off.

[0047] Step S500: When the desired current is not less than the second current threshold, control the first sampling switch module 100 to turn off and the second sampling switch module 200 to conduct.

[0048] Step S600: When the desired current is not less than the first current threshold and less than the second current threshold, control the first sampling switch module 100 and the second sampling switch module 200 to conduct simultaneously.

[0049] It can be understood that step S400 can cooperate with step S100 to achieve the working current sampling when the desired current is less than the first current threshold. Step S500 can cooperate with step S200 to achieve the working current sampling when the desired current is not less than the second current threshold. Step S600 can cooperate with step S300 to achieve the working current sampling when the desired current is not less than the first current threshold and less than the second current threshold.

[0050] By controlling the conduction and cutoff of the first sampling switch module 100 and the second sampling switch module 200, the control of the current input to the first input terminal and the second input terminal of the sampling module 300 can be achieved.

[0051] In one embodiment, the first current threshold is greater than the minimum value of the ideal input current of the second input terminal of the sampling module 300, and the second current threshold is less than the maximum value of the ideal input current of the first input terminal of the sampling module 300.

[0052] It can be understood that each sampling channel has a corresponding ideal current input range. The closer the working current is to the critical value of the ideal input current, the more likely the sampling module 300 is to have sampling errors and signal distortion. By making the first current threshold greater than the minimum value of the ideal input current of the second input terminal of the sampling module 300 and the second current threshold less than the maximum value of the ideal input current of the first input terminal of the sampling module 300, the switching of the sampling channel at the critical value of the ideal input current can be avoided, and the stability of sampling can be improved.

[0053] Figure 5 The schematic diagram of a multi-stage dimming circuit provided by an embodiment of the present application is shown. For the convenience of description, only the parts related to this embodiment are shown and are described in detail as follows:

[0054] A multi-stage dimming circuit 30 includes a multi-stage sampling circuit 10 and a control module 400.

[0055] The multi-stage sampling circuit 10 is used to sample the working current of the light-emitting module 20. Both the first input terminal and the second input terminal of the multi-stage sampling circuit 10 are connected to the output terminal of the light-emitting module 20.

[0056] The multi-stage sampling circuit 10 is used to sample the current of the first input terminal and amplify it at a first magnification to obtain a first sampling current, or to sample the current of the second input terminal and amplify it at a second magnification to obtain a second sampling current. The first magnification is greater than the second magnification; the control module 400 is connected to the multi-stage sampling circuit 10.

[0057] The control module 400 is used to obtain the working current according to the first sampling current when the desired current is less than the first current threshold.

[0058] When the desired current is not less than the second current threshold, the working current is obtained according to the second sampling current; the second current threshold is greater than the first current threshold.

[0059] When the desired current is not less than the first current threshold and less than the second current threshold, the working current is obtained according to the first sampling current and the second sampling current.

[0060] It can be understood that the control module 400 is used to implement steps S100 to S300 of the current sampling method according to any one of the above embodiments. By steps S100 to S300, when switching the sampling channels, the change of the obtained working current can be made smoother, avoiding the jitter of the working current.

[0061] In one embodiment, the multi-stage sampling circuit 10 includes: a first sampling switch module 100, a second sampling switch module 200, and a sampling module 300. The first sampling switch module 100 is connected between the light-emitting module 20 and the first input end of the sampling module 300;

[0062] The second sampling switch module 200 is connected between the light-emitting module 20 and the second input end of the sampling module 300;

[0063] The sampling module 300 is used to sample the current at the first input end and amplify it at a first magnification to obtain a first sampling current, or to sample the current at the second input end and amplify it at a second magnification to obtain a second sampling current, where the first magnification is greater than the second magnification;

[0064] The control module 400 is respectively connected to the first sampling switch module 100, the second sampling switch module 200, and the sampling module 300;

[0065] The control module 400 is further used to control the first sampling switch module 100 to conduct and the second sampling switch module 200 to turn off when the desired current is less than the first current threshold;

[0066] When the desired current is not less than the second current threshold, control the first sampling switch module 100 to turn off and the second sampling switch module 200 to conduct;

[0067] When the desired current is not less than the first current threshold and less than the second current threshold, control the first sampling switch module 100 to turn off and the second sampling switch module 200 to conduct simultaneously.

[0068] It can be understood that the control module 400 is used to implement steps S400 to S600 of the current sampling method according to any one of the above embodiments. By controlling the conduction and turning off of the first sampling switch module 100 and the second sampling switch module 200, the control of the current input to the first input end and the second input end of the sampling module 300 can be realized.

[0069] In one embodiment, the sampling module 300 includes a first current sampling unit 310 and a second current sampling unit 320. The input end of the second current sampling unit 320 is connected to the output end of the second sampling switch module 200, and the output end of the second current sampling unit 320 is grounded. The input end of the first current sampling unit 310 is connected to the output end of the first sampling switch module 100, and the output end of the first current sampling unit 310 is connected to the input end of the second current sampling unit 320. Both the first current sampling unit 310 and the second current sampling unit 320 are connected to the control module 400.

[0070] The input end of the first current sampling unit 310 is the first input end of the sampling module 300, and the input end of the second current sampling unit 320 is the second input end of the sampling module 300. The first current sampling unit 310 is configured to sample the current at the first input end and amplify it at a first magnification to obtain a first sampled current. The second current sampling unit 320 is configured to sample the current at the second input end and amplify it at a second magnification to obtain a second sampled current.

[0071] In one embodiment, the control module 400 includes a control unit 410 and a driving unit 420.

[0072] The control unit 410 is connected to the sampling module 300 and is configured to: obtain the operating current of the light-emitting module 20 based on the first sampled current or the second sampled current.

[0073] The driving unit 420 is respectively connected to the first sampling switch module 100, the second sampling switch module 200, and the control unit 410. The control unit 410 is further configured to control the driving unit 420 to transmit a first control signal and a second control signal to the first sampling switch module 100 and the second sampling switch module 200 respectively. The first control signal is used to control the first sampling switch module 100 to conduct, and the second control signal is used to control the second sampling switch module 200 to conduct.

[0074] Wherein, the control unit 410 may include a microcontroller (Microcontroller Unit; MCU), and the driving unit 420 may include a Pulse Width Modulation (PWM) chip.

[0075] When the sampled current is an analog signal, the control unit 410 may further perform analog-to-digital conversion on the first sampled current and the second sampled current to obtain corresponding digital signals.

[0076] In one embodiment, the multi-level dimming circuit 30 further includes a power module 500, and the power module 500 is respectively connected to the light-emitting module 20 and the control module 400.

[0077] The control module 400 is further configured to obtain the operating current of the light-emitting module 20 based on the first sampled current and the second sampled current, and adjust the output power of the power module 500 according to the operating current and the desired current.

[0078] It can be understood that by adjusting the output power of the power module 500, the voltage and current supplied to the light-emitting module 20 can be changed, so that the operating current approaches the desired current until the operating current is equal to the desired current or until the operating current dynamically changes within a certain range above and below the desired current, realizing the constant-current drive of the light-emitting module 20.

[0079] Figure 6 The schematic diagram of the lighting device provided by an embodiment of the present application is shown. For the sake of convenience of description, only the parts related to this embodiment are shown and are described in detail as follows:

[0080] A lighting device 40 includes a light-emitting module 20 and a multi-level dimming circuit 30 as described in any one of the above embodiments. The multi-level dimming circuit 30 is connected to the light-emitting module 20 and is configured to adjust the operating current of the light-emitting module 20.

[0081] In an embodiment, the lighting device 40 further includes a host computer 50. The host computer 50 is connected to the multi-level dimming circuit 30, and the host computer 50 is configured to provide a control signal corresponding to the desired current to the multi-level dimming circuit 30.

[0082] The host computer 50 can obtain the desired current and output the corresponding control signal by means of human-computer interaction or communication with other devices.

[0083] Those skilled in the art can clearly understand that for the convenience and simplicity of description, only the above-mentioned division of each functional unit and module is used as an example. In practical applications, the above functions can be allocated to different functional units and modules according to needs, that is, the internal structure of the device is divided into different functional units or modules to complete all or part of the functions described above. Each functional unit and module in the embodiment can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit. The above integrated unit can be implemented in the form of hardware or in the form of a software functional unit. In addition, the specific names of each functional unit and module are only for the convenience of mutual distinction and do not limit the protection scope of the present application. The specific working process of the units and modules in the above system can refer to the corresponding process in the foregoing method embodiment and will not be elaborated herein.

[0084] In the above embodiments, the descriptions of the respective embodiments have their own emphases. For the parts not detailed or recorded in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0085] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A current sampling method, characterized in that, Applied to a multi-stage sampling circuit (10), the multi-stage sampling circuit (10) is used to sample the working current of the light-emitting module (20), and both the first input end and the second input end of the multi-stage sampling circuit (10) are connected to the output end of the light-emitting module (20); The multi-stage sampling circuit (10) is used to sample the current at the first input end and amplify it at a first magnification to obtain a first sampled current, and to sample the current at the second input end and amplify it at a second magnification to obtain a second sampled current. The first magnification is greater than the second magnification, and the sampling accuracy of the first sampled current is greater than that of the second sampled current; The current sampling method includes: When the expected current is less than the first current threshold, obtaining the working current according to the first sampled current; When the expected current is not less than the second current threshold, obtaining the working current according to the second sampled current; the second current threshold is greater than the first current threshold; When the expected current is not less than the first current threshold and less than the second current threshold, obtaining the working current according to the first sampled current and the second sampled current.

2. The current sampling method according to claim 1, wherein The obtaining the working current according to the first sampled current and the second sampled current includes: Obtaining a first proportionality coefficient and a second proportionality coefficient according to the expected current, the first current threshold, and the second current threshold; wherein, the first proportionality coefficient is equal to the difference between the second current threshold and the expected current divided by the difference between the second current threshold and the first current threshold, and the sum of the first proportionality coefficient and the second proportionality coefficient is equal to 1; Adding the product of the first sampled current and the first proportionality coefficient to the product of the second sampled current and the second proportionality coefficient to obtain the working current.

3. The current sampling method according to claim 1, characterized in that, The multi-stage sampling circuit (10) includes: a first sampling switch module (100), a second sampling switch module (200), and a sampling module (300). The first sampling switch module (100) is connected between the light-emitting module (20) and the first input end of the sampling module (300); The second sampling switch module (200) is connected between the light-emitting module (20) and the second input end of the sampling module (300); The sampling module (300) is used to sample the current at the first input end and amplify it at a first magnification to obtain a first sampled current, or to sample the current at the second input end and amplify it at a second magnification to obtain a second sampled current. The first magnification is greater than the second magnification, and the sampling accuracy of the first sampled current is greater than that of the second sampled current; The current sampling method further includes: When the expected current is less than the first current threshold, controlling the first sampling switch module (100) to conduct and the second sampling switch module (200) to turn off; When the expected current is not less than the second current threshold, controlling the first sampling switch module (100) to turn off and the second sampling switch module (200) to conduct; When the desired current is not less than the first current threshold and less than the second current threshold, control the first sampling switch module (100) and the second sampling switch module (200) to conduct simultaneously.

4. The current sampling method according to claim 3, wherein The first current threshold is greater than the minimum value of the ideal input current of the second input terminal of the sampling module (300), and the second current threshold is less than the maximum value of the ideal input current of the first input terminal of the sampling module (300).

5. A multi - level dimming circuit (30), characterized in that, It includes a multi-stage sampling circuit (10) and a control module (400); The multi-stage sampling circuit (10) is used to sample the operating current of the light-emitting module (20), and both the first input terminal and the second input terminal of the multi-stage sampling circuit (10) are connected to the output terminal of the light-emitting module (20); The multi-stage sampling circuit (10) is used to sample the current at the first input terminal and amplify it at a first magnification to obtain a first sampled current, or to sample the current at the second input terminal and amplify it at a second magnification to obtain a second sampled current, where the first magnification is greater than the second magnification; the control module (400) is connected to the multi-stage sampling circuit (10); The control module (400) is used to obtain the operating current according to the first sampled current when the desired current is less than the first current threshold; When the desired current is not less than the second current threshold, obtain the operating current according to the second sampled current; the second current threshold is greater than the first current threshold; When the desired current is not less than the first current threshold and less than the second current threshold, obtain the operating current according to the first sampled current and the second sampled current.

6. The multi-stage dimming circuit (30) according to claim 5, wherein, The multi-stage sampling circuit (10) includes: a first sampling switch module (100), a second sampling switch module (200), and a sampling module (300), and the first sampling switch module (100) is connected between the light-emitting module (20) and the first input terminal of the sampling module (300); The second sampling switch module (200) is connected between the light-emitting module (20) and the second input terminal of the sampling module (300); The sampling module (300) is used to sample the current at the first input terminal and amplify it at a first magnification to obtain a first sampled current, or to sample the current at the second input terminal and amplify it at a second magnification to obtain a second sampled current, where the first magnification is greater than the second magnification; The control module (400) is respectively connected to the first sampling switch module (100), the second sampling switch module (200), and the sampling module (300); The control module (400) is further used to control the first sampling switch module (100) to conduct and the second sampling switch module (200) to turn off when the desired current is less than the first current threshold; When the desired current is not less than the second current threshold, control the first sampling switch module (100) to turn off and the second sampling switch module (200) to conduct; When the desired current is not less than the first current threshold and less than the second current threshold, control the first sampling switch module (100) to turn off and the second sampling switch module (200) to turn on simultaneously.

7. The multi-stage dimming circuit (30) according to claim 6, characterized in that, The control module (400) includes a control unit (410) and a driving unit (420); The control unit (410) is connected to the sampling module (300), and the control unit (410) is configured to: obtain the working current of the light-emitting module (20) according to the first sampling current or the second sampling current; The driving unit (420) is respectively connected to the first sampling switch module (100), the second sampling switch module (200) and the control unit (410). The control unit (410) is further configured to control the driving unit (420) to transmit a first control signal and a second control signal to the first sampling switch module (100) and the second sampling switch module (200) respectively. The first control signal is used to control the first sampling switch module (100) to turn on, and the second control signal is used to control the second sampling switch module (200) to turn on.

8. The multi - stage dimming circuit (30) according to claim 5, characterized in that, The multi-level dimming circuit (30) further includes a power module (500), and the power module (500) is respectively connected to the light-emitting module (20) and the control module (400); The control module (400) is further configured to obtain the working current of the light-emitting module (20) according to the first sampling current and the second sampling current, and adjust the output power of the power module (500) according to the working current and the desired current.

9. A lighting device (40), characterized in that, It includes a light-emitting module (20) and the multi-level dimming circuit (30) according to any one of claims 5 to 8. The multi-level dimming circuit (30) is connected to the light-emitting module (20) and is used to adjust the working current of the light-emitting module (20).

10. The lighting device (40) according to claim 9, characterized in that, The lighting device (40) further includes a host computer (50). The host computer (50) is connected to the multi-level dimming circuit (30), and the host computer (50) is used to provide a control signal corresponding to the desired current to the multi-level dimming circuit (30).

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