LED dimming driving circuit, method and device with wide dimming range

Abstract

The invention relates to an LED dimming driving circuit, method and device with a wide dimming range. The circuit comprises a microprocessor, a constant current circuit and a current shaping circuit, wherein the constant current circuit and the current shaping circuit are connected with the microprocessor; the constant current circuit is used for generating constant current for driving the LED to emit light under the control of the microprocessor; the current shaping circuit is connected with the constant current circuit and is used for inputting constant current into the LED under the control of the microprocessor; wherein when adjustment is carried out in a preset brightness range, the current shaping circuit inputs constant current into the LED, and the luminance of the LED is adjusted; when adjustment is carried out below a preset brightness range, the current shaping circuit shapes the constant current into a current pulse, and the light emitting brightness of the LED is controlled based on the current pulse. By adopting the dimming driving circuit, the dimming brightness can be divided into a preset brightness range and two parts below the preset brightness range for combined control, so that the lower limit of a conventional brightness range is expanded, the limitation of ripple waves on brightness adjustment is solved, and the adjustment of an LED in a wider brightness range is realized.

Description

Technical Field

[0001] The present application relates to the field of LED driving technology, and in particular to an LED dimming driving circuit, method and device with a wide dimming range. Background Art

[0002] LED dimming drive circuit is a very common hardware circuit, which adjusts the LED luminous intensity by adjusting the current flowing through the LED. The adjustment range of the current directly determines the adjustment range of the LED light brightness.

[0003] Currently, common LED dimming drive circuits are mainly implemented using switching power supply technology, which can achieve high-power and low-loss drive output, such as BUCK step-down constant current circuits.

[0004] However, the dimming drive circuit implemented based on the switching power supply technology must have current ripple due to the characteristics of the circuit topology. The existence of current ripple directly limits the range of the minimum controllable brightness adjustment that can be achieved by the drive circuit, making it difficult to dim the LED within a wider dimming range. Summary of the invention

[0005] Based on this, it is necessary to provide an LED dimming driving circuit, method and device that can broaden the brightness adjustment range and have a wide dimming range with an extremely low dimming lower limit in order to solve the above technical problems.

[0006] In a first aspect, the present application proposes an LED dimming driving circuit with a wide dimming range, the circuit comprising:

[0007] A microprocessor and a constant current circuit and a current shaping circuit connected to the microprocessor;

[0008] The constant current circuit is used to generate a constant current for driving the LED to emit light under the control of the microprocessor;

[0009] The current shaping circuit is connected to the constant current circuit and is used to input the constant current into the LED under the control of the microprocessor;

[0010] Among them, when adjusting within the preset brightness range, the current shaping circuit inputs the constant current into the LED to adjust the luminous brightness of the LED; when adjusting below the preset brightness range, the current shaping circuit shapes the constant current into a current pulse, and controls the luminous brightness of the LED based on the current pulse.

[0011] In one embodiment, the current shaping circuit includes:

[0012] A first shaping unit, a second shaping unit and a third shaping unit connected in parallel; the first shaping unit, the second shaping unit and the third shaping unit are connected to the inductance of a constant current circuit;

[0013] The first shaping unit is connected to the LED to light up the LED based on the current input into the first shaping unit;

[0014] The second shaping unit is used to perform a short-circuit operation on the LED when the LED is turned off, and dissipate the current in the inductor;

[0015] The third shaping unit is used to pre-charge the inductor with current before lighting the LED.

[0016] In one embodiment, the first shaping unit includes a first field effect tube, a first end of the first field effect tube is connected to the microprocessor, a second end of the first field effect tube is connected to the inductor through the LED; and a third end of the first field effect tube is grounded;

[0017] The second shaping unit includes a second field effect tube and a load, wherein a first end of the second field effect tube is connected to the microprocessor, and a second end of the second field effect tube is connected to the inductor through the load; and a third end of the second field effect tube is grounded;

[0018] The third shaping unit includes a third field effect tube, a first end of the third field effect tube is connected to the microprocessor, a second end of the third field effect tube is connected to the inductor; and a third end of the third field effect tube is grounded.

[0019] In one of the embodiments, the current shaping circuit further includes: a fourth shaping unit connected in parallel with the first shaping unit;

[0020] The fourth shaping unit is used to increase the voltage across the LED to form a current pulse when adjusting below the preset brightness range.

[0021] In one embodiment, the fourth shaping unit includes a fourth field effect transistor and an adjustment capacitor;

[0022] The first end of the fourth field effect tube is connected to the microprocessor, the second end of the fourth field effect tube is connected to the inductor through the adjustment capacitor; and the third end of the fourth field effect tube is grounded.

[0023] In one of the embodiments, the LED dimming driving circuit with a wide dimming range further includes: a light intensity feedback circuit connected to the microprocessor;

[0024] When adjusting within the preset brightness range, the light intensity feedback circuit is used to detect the first luminous intensity of the LED and feed back the first detection result to the microprocessor to maintain the luminous intensity of the LED at the target brightness;

[0025] When adjusting below the preset brightness range, the light intensity feedback circuit is used to detect the second luminous intensity of the LED and feed back the second detection result to the microprocessor to form a current pulse.

[0026] In one of the embodiments, the LED dimming driving circuit with a wide dimming range further includes: a protection circuit;

[0027] One end of the protection circuit is connected to the microprocessor, and the other end of the protection circuit is connected to the current shaping circuit, which is used for overcurrent protection control of the circuit.

[0028] In one embodiment, the constant current circuit includes a Buck constant current circuit and a current preset circuit;

[0029] The current preset circuit is used to adjust the constant current output by the Buck constant current circuit.

[0030] In a second aspect, the present application further provides a wide dimming range LED dimming driving method, which is applicable to a wide dimming range LED dimming driving circuit; the method comprises:

[0031] Within a preset brightness range, the brightness of the LED is controlled based on the constant current output by the constant current circuit;

[0032] Below the preset brightness range, the current shaping circuit is controlled to shape the constant current output into a current pulse, and the light emitting brightness of the LED is controlled based on the current pulse.

[0033] In one embodiment, within a preset brightness range, controlling the light emitting brightness of an LED based on a constant current output by a constant current circuit includes:

[0034] When the target brightness is within a preset brightness range, the two ends of the constant current waveform output by the constant current circuit are shaped, and the LED is controlled to reach the target brightness based on the shaped rectangular constant current output.

[0035] In one embodiment, below the preset brightness range, controlling the current shaping circuit to shape the constant current output into a current pulse, and controlling the light emitting brightness of the LED based on the current pulse, comprises:

[0036] When the target brightness is below the preset brightness range, controlling the current shaping circuit to shape the constant current output to obtain a triangular pulse;

[0037] The LED is controlled to achieve the target brightness based on the shape and number of the triangular pulses.

[0038] In a third aspect, the present application further provides an LED dimming driving device with a wide dimming range, the device comprising:

[0039] A conventional brightness module is used to control the brightness of the LED within a preset brightness range based on the constant current output by the constant current circuit;

[0040] The extremely low brightness module is used to control the current shaping circuit to shape the constant current output into a current pulse below the preset brightness range, and control the light emitting brightness of the LED based on the current pulse.

[0041] The above-mentioned LED dimming driving circuit, method and device with a wide dimming range include a microprocessor and a constant current circuit and a current shaping circuit connected to the microprocessor; the constant current circuit is used to generate a constant current for driving the LED to emit light under the control of the microprocessor; the current shaping circuit is connected to the constant current circuit and is used to input the constant current into the LED under the control of the microprocessor; wherein, when adjusting within a preset brightness range, the current shaping circuit inputs the constant current into the LED to adjust the luminous brightness of the LED; when adjusting below the preset brightness range, the current shaping circuit shapes the constant current into a current pulse, controls the luminous brightness of the LED based on the current pulse, and divides the dimming brightness into two parts: a preset brightness range and a part below the preset brightness range for combined control, thereby expanding the lower limit of the conventional brightness range, solving the limitation of ripple on brightness adjustment, and realizing adjustment of a wider brightness range of the LED. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0043] Figure 1 Schematic diagram of the structure of an LED dimming driving circuit with a wide dimming range in one embodiment;

[0044] Figure 2 A schematic diagram showing a comparison between an LED dimming range in an embodiment and a dimming range in a conventional implementation;

[0045] Figure 3-A A circuit diagram of an LED dimming drive circuit with a wide dimming range in an embodiment;

[0046] Figure 3-BA schematic diagram of a specific implementation circuit of current control and shaping within a preset brightness range in one embodiment;

[0047] Figure 3-C A schematic diagram of a specific implementation circuit of current control and shaping within a preset brightness range in one embodiment;

[0048] Figure 4-A A schematic diagram showing a comparison of a constant current waveform before and after shaping within a preset brightness range in an embodiment;

[0049] Figure 4-B A schematic diagram of current control and shaping within a preset brightness range in an embodiment;

[0050] Figure 5 A schematic diagram of pulse current control and shaping within a preset brightness range in one embodiment;

[0051] Figure 6 Schematic diagram of a flow chart of a LED dimming driving method with a wide dimming range in one embodiment;

[0052] Figure 7 FIG. 4 is a structural block diagram of an LED dimming driving device with a wide dimming range in an embodiment.

[0053] Figure numerals: 11, microprocessor; 12, constant current circuit; 121, Buck constant current circuit; 122, current preset circuit; 13, current shaping circuit; 14, light intensity feedback circuit; 15, protection circuit. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is further described in detail below in conjunction with 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 intended to limit the present application. Based on the embodiments provided in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0055] Obviously, the drawings described below are only some examples or embodiments of the present application. For ordinary technicians in this field, the present application can also be applied to other similar scenarios based on these drawings without creative work. In addition, it can also be understood that although the efforts made in this development process may be complicated and lengthy, for ordinary technicians in this field related to the content disclosed in this application, some changes in design, manufacturing or production based on the technical content disclosed in this application are just conventional technical means, and should not be understood as the content disclosed in this application is insufficient.

[0056] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those of ordinary skill in the art that the embodiments described in this application may be combined with other embodiments without conflict.

[0057] Unless otherwise defined, the technical terms or scientific terms involved in this application should be understood by people with ordinary skills in the technical field to which this application belongs. The words "one", "a", "a", "the" and the like involved in this application do not indicate a quantitative limitation, and may represent the singular or plural. The terms "include", "comprise", "have" and any of their variations involved in this application are intended to cover non-exclusive inclusions; for example, a process, method, system, product or device that includes a series of steps or modules (units) is not limited to the listed steps or units, but may also include steps or units that are not listed, or may also include other steps or units inherent to these processes, methods, products or devices. The words "connect", "connected", "coupled" and the like involved in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The "multiple" involved in this application refers to two or more. "And / or" describes the association relationship of associated objects, indicating that there may be three relationships, for example, "A and / or B" can represent: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the objects before and after are in an "or" relationship. The terms "first", "second", "third", etc. involved in this application are only used to distinguish similar objects and do not represent a specific ordering of the objects.

[0058] In this embodiment, a LED dimming driving circuit with a wide dimming range is provided. Figure 1 As shown, the LED dimming driving circuit with a wide dimming range includes:

[0059] A microprocessor 11 and a constant current circuit 12 and a current shaping circuit 13 connected to the microprocessor 11 .

[0060] The constant current circuit 12 is used to generate a constant current for driving the LED to emit light under the control of the microprocessor 11 .

[0061] The current shaping circuit 13 is connected to the constant current circuit 12 and is used to input the constant current into the LED under the control of the microprocessor 11 .

[0062] Among them, when adjusting within the preset brightness range, the current shaping circuit 13 inputs a constant current into the LED to adjust the luminous brightness of the LED; when adjusting below the preset brightness range, the current shaping circuit 13 shapes the constant current into a current pulse, and controls the luminous brightness of the LED based on the current pulse.

[0063] The microprocessor 11 may be implemented by an MCU (Microcontroller Unit), an FPGA (Field Programmable Gate Array) or any other digital circuit.

[0064] like Figure 2 As shown in the left figure, the existing LED dimming solution uses Buck constant current for dimming within the full dimming range. When the current value is at the I-low position, the peak and valley of the current ripple have reached the lower limit of the circuit. Assuming that its peak current is 1A, the current average is 0.5A, indicating that its dimming lower limit is 0.5A. Therefore, the full dimming range of the existing conventional solution is small, especially in the low brightness area, the dimming is limited by ripple. Specifically, the ripple ratio is usually 10% of the rated current, then the conventional brightness refers to the distortion-free brightness above 10% of the rated current, and the extremely low brightness is the brightness below 10%. In this embodiment, the preset brightness range is set based on the distortion-free brightness above 10% of the rated current.

[0065] like Figure 2 As shown in the right figure of FIG. 1 , this embodiment divides the dimming range into two parts: a preset brightness and a part below the preset brightness. Figure 2 The effect is consistent with that shown in the middle left figure. When the peak and valley of the current ripple reaches the lower limit of the circuit, the current shaping circuit 13 is used to shape the current flowing through the LED into a pulse, and the shape and number of the light-emitting pulses are controlled to adjust the brightness of the LED light.

[0066] The LED dimming driving circuit with a wide dimming range of the present embodiment can utilize the constant current circuit 12 and the current shaping circuit 13 to divide the dimming brightness into two parts, a preset brightness range and two parts below the preset brightness range, for combined control; wherein the preset brightness range utilizes the constant current circuit 12 to adopt continuous constant current light output control, and the range below the preset brightness range utilizes the constant current circuit 12 and the current shaping circuit 13 to adopt pulse shaping light output control, which has the function of adjusting the light output brightness within a wide range to achieve an extremely low dimming lower limit, and within the full dimming range, the circuit's own power loss is small, and the effective utilization rate of the power supply is high.

[0067] In one embodiment, see Figure 1 The LED dimming driving circuit with a wide dimming range also includes: a light intensity feedback circuit 14 connected to the microprocessor 11.

[0068] When adjusting within the preset brightness range, the light intensity feedback circuit 14 is used to detect the first luminous intensity of the LED and feed back the first detection result to the microprocessor 11 to maintain the luminous intensity of the LED at the target brightness.

[0069] When adjusting below the preset brightness range, the light intensity feedback circuit 14 is used to detect the second luminous intensity of the LED and feed back the second detection result to the microprocessor 11 to form a current pulse.

[0070] Specifically, the light intensity feedback circuit 14 includes a photoelectric converter PD, a trans-impedance amplifier TIA (Trans-Impedance Amplifier, TIA), a second digital-to-analog converter DAC2 and a comparator. The light intensity feedback circuit 14 converts the actual light intensity into a voltage value and inputs it into the comparator to compare it with the preset value and make adjustments.

[0071] In one embodiment, see Figure 1 and Figure 3-A The LED dimming driving circuit with a wide dimming range also includes: a protection circuit 15; one end of the protection circuit 15 is connected to the microprocessor 11, and the other end of the protection circuit 15 is connected to the current shaping circuit 13 for overcurrent protection control of the circuit.

[0072] Specifically, the protection circuit 15 includes a second resistor R2 and an analog-to-digital converter ADC (Analog-to-Digital Converter).

[0073] In one embodiment, see Figure 1 and Figure 3-A The constant current circuit 12 includes a Buck constant current circuit 121 and a current preset circuit 122 ; the current preset circuit 122 is used to adjust the constant current output by the Buck constant current circuit 121 .

[0074] Specifically, the Buck constant current circuit 121 includes components such as a Buck chip, a first resistor R1, a constant current field effect transistor Q5, and an inductor L; the first end of the Buck chip is connected to the microprocessor 11, and is used to receive the on and off control signals issued by the microprocessor 11, the second end of the Buck chip is connected to the power input, and the third end of the Buck chip is connected to the first end of the constant current field effect transistor Q5; the second end of the constant current field effect transistor Q5 is connected to the power input through the first resistor R1, the third end of the constant current field effect transistor Q5 is connected to one end of the inductor L, and the other end of the inductor L is connected to the current shaping circuit 13.

[0075] The current preset circuit 122 is used to control the current size, and includes a first digital to analog converter DAC1 (Digital to analog converter, DAC), a current preset field effect transistor Q6, and an ILIM resistor. One end of the DAC1 is connected to the microprocessor 11, and the other end is connected to the first end of the current preset field effect transistor Q6. The second end of the current preset field effect transistor Q6 is connected to the Buck constant current circuit 121, and the third end of the current preset field effect transistor Q6 is connected to the ILIM resistor. By adjusting the output of the DAC1, the current size output by the Buck constant current circuit 121 can be adjusted.

[0076] In one embodiment, the current shaping circuit 13 includes: a first shaping unit, a second shaping unit and a third shaping unit connected in parallel; the first shaping unit, the second shaping unit and the third shaping unit are connected to the inductor L of the constant current circuit 12 .

[0077] The first shaping unit is connected to the LED to light up the LED based on the current input into the first shaping unit.

[0078] The second shaping unit is used to perform a short-circuit operation on the LED when the LED is turned off, and to dissipate the current in the inductor L.

[0079] The third shaping unit is used to pre-charge the inductor L with current before lighting the LED.

[0080] It should be noted that see Figure 4-A When driven by the constant current circuit 12, there is a rising delay Tr and a falling edge delay Tf due to the inductive reactance of the current step; the existence of the delay causes the LED to light up and extinguish not quickly and sharply and causes LED light delay and smearing. Through the combined control of the first shaping unit, the second shaping unit and the third shaping unit connected in parallel, the edge of the current can be shaped to obtain a rectangular current, thereby eliminating the light delay and smearing phenomenon.

[0081] For details, see Figure 4-B The second shaping unit quickly turns off the LED in the dissipation stage, and the third shaping unit quickly lights up the LED with the help of the pre-charging stage, thereby achieving Figure 3-A The shaping effect shown.

[0082] In one embodiment, if Figure 3-A As shown, the first shaping unit includes a first field effect transistor Q1, a first end of the first field effect transistor Q1 is connected to the microprocessor 11, a second end of the first field effect transistor Q1 is connected to the inductor L through an LED; and a third end of the first field effect transistor Q1 is grounded.

[0083] The second shaping unit includes a second field effect transistor Q2 and a load. The first end of the second field effect transistor Q2 is connected to the microprocessor 11, and the second end of the second field effect transistor Q2 is connected to the inductor L through the load; the third end of the second field effect transistor Q2 is grounded.

[0084] The third shaping unit includes a third field effect transistor Q3, a first end of the third field effect transistor Q3 is connected to the microprocessor 11, a second end of the third field effect transistor Q3 is connected to the inductor L; and a third end of the third field effect transistor Q3 is grounded.

[0085] For details, see Figure 4-B and Figure 3-B The current shaping circuit 13 is controlled in four stages to achieve accurate adjustment of the LED brightness within a preset brightness range:

[0086] ① In the dissipation stage, the constant current circuit 12 is turned off and Q2 is enabled to short-circuit the LED, thereby dissipating the inductor current and quickly turning off the LED.

[0087] ② In the pre-charge stage, Q2 is disabled and Q3 is enabled, and then the constant current circuit is turned on to perform current pre-charge operation on the inductor L.

[0088] ③ In the light-emitting stage, Q3 is disabled to cancel the LED short circuit, and the current is forced to flow into the LED according to the preset value, and the LED lights up instantly.

[0089] ④ Feedback stage: the first luminous intensity is detected by PD to adjust and maintain the LED light intensity amplitude.

[0090] In this way, the current shaping circuit 13 outputs a rectangular waveform to control the LED, and performs feedback compensation by detecting the actual light output brightness, maintaining the actual light output brightness at a preset value, thereby eliminating light emission delay and smearing, accurately controlling brightness switching, and avoiding light output abnormalities caused by device differences, temperature drift, time drift, etc.

[0091] In one embodiment, the current shaping circuit 13 further includes: a fourth shaping unit connected in parallel with the first shaping unit; the fourth shaping unit is used to increase the voltage across the LED to form a current pulse when adjusting below a preset brightness range.

[0092] For details, see Figure 5 , the fourth shaping unit is used to obtain a current pulse for controlling the lighting of the LED.

[0093] In one embodiment, if Figure 3-A As shown, the fourth shaping unit includes a fourth field effect transistor Q4 and an adjustment capacitor C; the first end of the fourth field effect transistor Q4 is connected to the microprocessor 11, and the second end of the fourth field effect transistor Q4 is connected to the inductor L through the adjustment capacitor C; the third end of the fourth field effect transistor Q4 is grounded.

[0094] For details, see Figure 5 and Figure 3-C The current shaping circuit 13 is controlled in five stages to achieve accurate adjustment of the LED brightness within a preset brightness range:

[0095] ① In the dissipation stage, the constant current circuit 12 is turned off and Q2 is enabled to short-circuit the LED, thereby dissipating the inductor current and quickly turning off the LED.

[0096] ② In the pre-charge stage, Q2 is disabled and Q3 is enabled, and then the constant current circuit is turned on to perform current pre-charge operation on the inductor L.

[0097] ③ In the shaping stage, Q3 is disabled and Q1 and Q4 are enabled. The inductor current is forced to flow into the regulating capacitor C, causing the voltage to rise.

[0098] ④ In the light-emitting stage, the LED emits light immediately after the voltage reaches the light-emitting threshold.

[0099] ⑤In the feedback stage, the output light intensity amplitude is detected by PD. When the set threshold is reached, Q3 short-circuit LED is enabled to stop emitting light, and processes ③ to ⑤ are repeated after a specified delay time until the number of light-emitting pulses is met and the entire process ends.

[0100] In this way, the inductor L is dissipated with current, pre-charged with current and shaped into pulses, and the area and number of pulse waveforms are controlled to achieve precise dimming in low-brightness areas, greatly expanding the dimming range of the LED. Feedback compensation is performed by detecting the actual light output brightness to maintain the actual light output brightness at the preset value, avoiding light output abnormalities caused by device differences, temperature drift, time drift, etc.

[0101] In this embodiment, a LED dimming driving method with a wide dimming range is also provided, which is applicable to an LED dimming driving circuit with a wide dimming range; Figure 6 As shown, the method includes:

[0102] Step S210 , controlling the light emitting brightness of the LED based on the constant current output by the constant current circuit 12 within a preset brightness range.

[0103] Specifically, the microprocessor 11 of the LED dimming driving circuit with a wide dimming range controls the current shaping circuit 13 to start, and inputs the constant current output by the constant current circuit 12 into the LED to adjust the light brightness of the LED.

[0104] Step S220 , below a preset brightness range, controlling the current shaping circuit 13 to shape the constant current output into a current pulse, and controlling the light emitting brightness of the LED based on the current pulse.

[0105] Specifically, the microprocessor 11 controls the current shaping circuit 13 to shape the constant current output into current pulses, and the light intensity of the LED can be controlled by the shape and number of the current pulses at the same time.

[0106] It should be noted that the LED dimming driving method with a wide dimming range is applied to the microprocessor 11 of the LED dimming driving circuit with a wide dimming range. When the microprocessor 11 executes the stored computer program, the steps of the LED dimming driving method with a wide dimming range in any embodiment are implemented.

[0107] The LED dimming driving method with a wide dimming range of the present embodiment expands the lower limit of the conventional brightness range, solves the limitation of ripple on brightness adjustment, and realizes adjustment of a wider brightness range of the LED.

[0108] In one embodiment, within a preset brightness range, the light emitting brightness of the LED is controlled based on the constant current output by the constant current circuit 12, including:

[0109] Step S211, when the target brightness is within a preset brightness range, the two ends of the constant current waveform output by the constant current circuit 12 are shaped, and the LED is controlled to reach the target brightness based on the shaped rectangular constant current output.

[0110] Specifically, the microprocessor 11 turns off the constant current circuit 12 connected to the LED, controls the current shaping circuit 13 to short-circuit the LED, and dissipates the current of the inductor L in the constant current circuit 12 based on the current shaping circuit 13; after the current dissipation is completed, the constant current circuit 12 is turned on, and the inductor L is pre-charged with current based on the current shaping circuit 13; after the current pre-charging is completed, the short-circuit operation of the LED is canceled, and the shaped current is controlled to be input into the LED to light up the LED.

[0111] Within the specified time, the LED is kept lit based on the constant current waveform, and after the specified time is reached, the current shaping circuit 13 is controlled to quickly turn off the LED. Based on this, the constant current output can be switched to the next LED in the LED light group, and the next LED can be controlled to light up, and the above steps can be repeated to perform imaging display of the LED light group, so that each LED has a sharp light edge, stable imaging, and eliminates the smear effect.

[0112] This embodiment solves the LED light-emitting delay and smearing phenomenon by shaping the two ends of the constant current waveform output by the constant current circuit 12, and improves the timeliness of LED lighting and extinguishing.

[0113] In one embodiment, below a preset brightness range, the current shaping circuit 13 is controlled to shape the constant current output into a current pulse, and the light emitting brightness of the LED is controlled based on the current pulse, including:

[0114] Step S221, when the target brightness is below the preset brightness range, the current shaping circuit 13 is controlled to shape the constant current output to obtain a triangular pulse; based on the shape and number of the triangular pulse, the LED is controlled to reach the target brightness.

[0115] Specifically, the microprocessor 11 turns off the constant current circuit 12 connected to the LED, and controls the current shaping circuit 13 to short-circuit the LED, and dissipates the current of the inductor L in the constant current circuit 12 based on the current shaping circuit 13; after the current dissipation is completed, the constant current circuit 12 is turned on, and the inductor L is pre-charged with current based on the current shaping circuit 13; after the pre-charge current in the inductor L reaches a preset current value, the voltage across the LED is controlled to rise based on the current shaping circuit 13 to light up the LED; the second luminous intensity of the LED is detected, and when the second luminous intensity reaches a preset threshold value, the short-circuited LED stops emitting light; after the preset delay time is reached, the LED is repeatedly lit until the number of lighting times reaches a preset number.

[0116] Specifically, since constant current output is difficult to control the luminous effect in low-brightness areas, this embodiment uses triangular pulse shaping and counting control to adjust the brightness of the LED. The light intensity received by the human eye is the integral of time, that is, the cumulative value of the incident light intensity within a certain period of time corresponds to the brightness intensity that the human eye can feel. When the number of pulses is greater or the shape area is larger, the corresponding integrated light intensity is greater, and the perception is brighter.

[0117] In this way, adjusting the pulse shape and quantity simultaneously can accurately adjust the required light intensity and greatly expand the dimming range.

[0118] Based on the same inventive concept, a LED dimming driving device with a wide dimming range is also provided in this embodiment. The system is used to implement the above embodiments and preferred implementation modes, and the descriptions that have been made will not be repeated. The terms "module", "unit", "subunit", etc. used below can implement a combination of software and / or hardware for a predetermined function. Although the system described in the following embodiments is preferably implemented in software, the implementation of hardware, or a combination of software and hardware, is also possible and conceivable.

[0119] In one embodiment, if Figure 7 As shown, a LED dimming driving device with a wide dimming range is provided, the device comprising: a conventional brightness module 71 and an extremely low brightness module 72, wherein:

[0120] The conventional brightness module 71 is used to control the light emitting brightness of the LED within a preset brightness range based on the constant current output by the constant current circuit 12.

[0121] The extremely low brightness module 72 is used to control the current shaping circuit 13 to shape the constant current output into a current pulse below a preset brightness range, and control the light emitting brightness of the LED based on the current pulse.

[0122] In one embodiment, the conventional brightness module 71 is also used to shape the two ends of the constant current waveform output by the constant current circuit 12 when the target brightness is within a preset brightness range, and control the LED to reach the target brightness based on the shaped rectangular constant current output.

[0123] In one embodiment, the extremely low brightness module 72 is also used to control the current shaping circuit 13 to shape the constant current output to obtain a triangular pulse when the target brightness is below a preset brightness range; and control the LED to reach the target brightness based on the shape and number of the triangular pulses.

[0124] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0125] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A LED dimming driving circuit with a wide dimming range, characterized in that: The circuit comprises: A microprocessor and a constant current circuit and a current shaping circuit connected to the microprocessor; The constant current circuit is used to generate a constant current for driving the LED to emit light under the control of the microprocessor; The current shaping circuit is connected to the constant current circuit and is used to input the constant current into the LED under the control of the microprocessor; Among them, when adjusting within the preset brightness range, the current shaping circuit inputs the constant current into the LED to adjust the luminous brightness of the LED; when adjusting below the preset brightness range, the current shaping circuit shapes the constant current into a current pulse, and controls the luminous brightness of the LED based on the current pulse.

2. The LED dimming driving circuit with a wide dimming range as claimed in claim 1, characterized in that: The current shaping circuit comprises: A first shaping unit, a second shaping unit and a third shaping unit connected in parallel; the first shaping unit, the second shaping unit and the third shaping unit are connected to the inductance of a constant current circuit; The first shaping unit is connected to the LED to light up the LED based on the current input into the first shaping unit; The second shaping unit is used to perform a short-circuit operation on the LED when the LED is turned off, and dissipate the current in the inductor; The third shaping unit is used to pre-charge the inductor with current before lighting the LED.

3. The LED dimming driving circuit with a wide dimming range as claimed in claim 2, characterized in that: The first shaping unit includes a first field effect tube, a first end of the first field effect tube is connected to the microprocessor, a second end of the first field effect tube is connected to the inductor through the LED; and a third end of the first field effect tube is grounded; The second shaping unit includes a second field effect tube and a load, wherein a first end of the second field effect tube is connected to the microprocessor, and a second end of the second field effect tube is connected to the inductor through the load; and a third end of the second field effect tube is grounded; The third shaping unit includes a third field effect tube, a first end of the third field effect tube is connected to the microprocessor, a second end of the third field effect tube is connected to the inductor; and a third end of the third field effect tube is grounded.

4. The LED dimming driving circuit with a wide dimming range as claimed in claim 2, characterized in that: The current shaping circuit further includes: a fourth shaping unit connected in parallel with the first shaping unit; The fourth shaping unit is used to increase the voltage across the LED to form a current pulse when adjusting below the preset brightness range.

5. The LED dimming driving circuit with a wide dimming range as claimed in claim 4, characterized in that: The fourth shaping unit includes a fourth field effect transistor and an adjustment capacitor; The first end of the fourth field effect tube is connected to the microprocessor, the second end of the fourth field effect tube is connected to the inductor through the adjustment capacitor; and the third end of the fourth field effect tube is grounded.

6. The LED dimming driving circuit with a wide dimming range as claimed in claim 1, characterized in that: The LED dimming driving circuit with a wide dimming range further includes: a light intensity feedback circuit connected to the microprocessor; When adjusting within the preset brightness range, the light intensity feedback circuit is used to detect the first luminous intensity of the LED and feed back the first detection result to the microprocessor to maintain the luminous intensity of the LED at the target brightness; When adjusting below the preset brightness range, the light intensity feedback circuit is used to detect the second luminous intensity of the LED and feed back the second detection result to the microprocessor to form a current pulse.

7. The LED dimming driving circuit with a wide dimming range as claimed in claim 1, characterized in that: The LED dimming driving circuit with a wide dimming range further includes: a protection circuit; One end of the protection circuit is connected to the microprocessor, and the other end of the protection circuit is connected to the current shaping circuit, which is used for overcurrent protection control of the circuit.

8. The LED dimming driving circuit with a wide dimming range as claimed in claim 1, characterized in that: The constant current circuit includes a Buck constant current circuit and a current preset circuit; The current preset circuit is used to adjust the constant current output by the Buck constant current circuit.

9. A LED dimming driving method with a wide dimming range, characterized in that: An LED dimming driving circuit suitable for a wide dimming range; the method comprises: Within a preset brightness range, the brightness of the LED is controlled based on the constant current output by the constant current circuit; Below the preset brightness range, the current shaping circuit is controlled to shape the constant current output into a current pulse, and the light emitting brightness of the LED is controlled based on the current pulse.

10. The LED dimming driving method with a wide dimming range according to claim 9, characterized in that: Within the preset brightness range, the brightness of the LED is controlled based on the constant current output by the constant current circuit, including: When the target brightness is within a preset brightness range, the two ends of the constant current waveform output by the constant current circuit are shaped, and the LED is controlled to reach the target brightness based on the shaped rectangular constant current output.

11. The LED dimming driving method with a wide dimming range according to claim 9, characterized in that: Below the preset brightness range, controlling the current shaping circuit to shape the constant current output into a current pulse, and controlling the light emitting brightness of the LED based on the current pulse, including: When the target brightness is below the preset brightness range, controlling the current shaping circuit to shape the constant current output to obtain a triangular pulse; The LED is controlled to achieve the target brightness based on the shape and number of the triangular pulses.

12. An LED dimming driving device with a wide dimming range, characterized in that: The device comprises: A conventional brightness module is used to control the brightness of the LED within a preset brightness range based on the constant current output by the constant current circuit; The extremely low brightness module is used to control the current shaping circuit to shape the constant current output into a current pulse below the preset brightness range, and control the light emitting brightness of the LED based on the current pulse.

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