A dimming circuit, method and lighting device for a multi-segment light emitting diode

Abstract

The application is suitable for the technical field of electronic circuits, and provides a multi-section light-emitting diode (LED) dimming circuit, method and lighting device, which comprises a power supply output circuit, a whole-section LED, an LED dimming circuit and an LED constant current driving circuit, wherein the power supply output circuit is connected with the whole-section LED comprising a plurality of sub-section LEDs, is used for providing power supply for the whole-section LED, and outputs a line network voltage value; the LED dimming circuit is connected with the power supply output circuit and the whole-section LED respectively, is used for sampling the line network voltage value and a whole-section voltage difference value of the whole-section LED, and respectively outputs a thyristor control signal value and a dimming voltage value; the LED constant current driving circuit is connected with the LED dimming circuit, each sub-section LED and the power supply output circuit respectively, is used for providing a constant current for each sub-section LED according to the dimming voltage value, and determines to open or close a thyristor bleed circuit in the LED constant current driving circuit according to the thyristor control signal value. Thus, the linearity of low-brightness dimming is effectively improved.

Description

Technical Field

[0001] This application belongs to the field of electronic circuit technology, and in particular relates to a dimming circuit, method and lighting device for a multi-segment light-emitting diode. Background Technology

[0002] With the rapid development of LED lighting technology, LED lighting has become ubiquitous in all aspects of life, and the requirements for LED lighting usage are increasingly stringent in various regions. Existing constant current drive technology struggles to meet the diverse requirements for power factor (PF), total harmonic distortion (THD), and dimming methods across different regions. This is particularly true for multi-segment LED low-brightness dimming, where poor linearity and uneven surface light source uniformity remain unresolved. For example, when driving multi-segment LEDs, existing constant current drive products, when the grid voltage is switched to a level lower than the driving voltage of the last segment of the LED array, only the last segment turns off, while the remaining segments remain on. As the grid voltage continues to decrease, multiple segments turn off sequentially, resulting in poor surface light source uniformity. Conversely, directly turning off all segments when the switched grid voltage approaches the driving voltage of the last segment of the LED array fails to achieve linear brightness changes. Therefore, further research is needed to fill the technological gaps in multi-segment LED low-brightness dimming. Summary of the Invention

[0003] This application provides a dimming circuit, method, and lighting device for multi-segment LEDs, which can solve the problem of poor linearity when using existing constant current drive circuits for low-brightness dimming of multi-segment LEDs.

[0004] In a first aspect, embodiments of this application provide a dimming circuit for a multi-segment light-emitting diode (LED), the circuit comprising: a power output circuit, a full-segment LED, an LED dimming circuit, and an LED constant current drive circuit, wherein...

[0005] A complete LED segment consists of multiple sub-segments of LEDs;

[0006] The power output circuit is connected to the entire LED segment and is used to provide power to the entire LED segment and output the grid voltage value.

[0007] The LED dimming circuit is connected to the power output circuit and the entire LED segment respectively, and is used to sample the grid voltage value and the voltage difference of the entire LED segment, and output the thyristor control signal value and the dimming voltage value respectively.

[0008] The LED constant current driving circuit is connected to the LED dimming circuit, each of the sub-segments of LED, and the power output circuit, respectively. It is used to provide a constant current to each of the sub-segments of LED according to the dimming voltage value, and to determine whether to turn on or off the thyristor discharge circuit in the LED constant current driving circuit according to the thyristor control signal value.

[0009] In one possible implementation of the first aspect, the circuit further includes: an LED constant current detection circuit, wherein,

[0010] The LED constant current judgment circuit is connected to the negative terminal of the entire LED segment and is used to determine whether the voltage flowing through the entire LED segment is less than the total lamp segment voltage value, and output the judgment result value.

[0011] The LED constant current driving circuit is also connected to the LED constant current judgment circuit, and is also used to determine whether to turn off the thyristor discharge circuit and the entire LED segment simultaneously based on the judgment result value.

[0012] In one possible implementation of the first aspect, the LED dimming circuit includes: a wire mesh detection circuit, an LED lamp voltage detection circuit, and an adaptive dimming reference circuit, wherein,

[0013] The wire network detection circuit is connected to the input terminal of the power output circuit. It is used to perform a first sampling process on the wire network voltage value, output the sampled voltage value, and determine whether the wire network voltage is shunted by the thyristor based on the wire network voltage value, and output the thyristor control signal value.

[0014] The LED lamp voltage detection circuit is connected to the input terminal of the power output circuit and the negative terminal of the entire LED segment, respectively, and is used to perform a second sampling process on the voltage difference of the entire LED segment and output the voltage threshold of the entire segment.

[0015] The adaptive dimming reference circuit is connected to the LED lamp pressure detection circuit and the wire mesh detection circuit, respectively, and is used to linearly compare the sampled voltage value output by the wire mesh detection circuit and the whole voltage threshold output by the LED lamp pressure detection circuit, and output the dimming voltage value.

[0016] In one possible implementation of the first aspect, the adaptive dimming reference circuit includes: a linear comparator, a first power switch, a first resistor, a second resistor, and a plurality of voltage divider resistors, wherein,

[0017] The positive input terminal of the linear comparator is connected to the first output terminal of the wire mesh detection circuit, and the negative input terminal of the linear comparator is connected to the output terminal of the LED lamp voltage detection circuit, which is used to perform a linear comparison between the sampled voltage value and the entire voltage threshold and output a dimming current;

[0018] The positive output terminal of the linear comparator is connected to the drain of the first power switch via the first resistor, the negative output terminal of the linear comparator is connected to the gate of the first power switch, and the source of the first power switch is grounded.

[0019] The input terminal of the first resistor is connected to the clamping voltage, and the output terminal of the first resistor is grounded after passing through a link composed of the second resistor and multiple voltage divider resistors connected in series.

[0020] The output terminals of the multiple voltage divider resistors are respectively connected to the LED constant current driving circuit, and the multiple dimming voltage values ​​output from the output terminals of the multiple voltage divider resistors are respectively input to the LED constant current driving circuit.

[0021] In one possible implementation of the first aspect, the number of the plurality of voltage divider resistors is the same as the number of the plurality of sub-segments of the whole LED, and the plurality of voltage divider resistors correspond one-to-one with the sub-segments of the LED.

[0022] In one possible implementation of the first aspect, the LED constant current driving circuit includes: a second power switch, a thyristor discharge circuit, and a constant current driving sub-circuit, wherein,

[0023] The input terminal of the thyristor discharge circuit is connected to the second output terminal of the wire mesh detection circuit, and the output terminal of the thyristor discharge circuit is connected to the input terminal of the constant current resistor. It is used to judge the value of the thyristor control signal and determine whether to turn the thyristor discharge circuit on or off.

[0024] The input terminal of the constant current driving sub-circuit is connected to the output terminals of the multiple voltage divider resistors in the adaptive dimming reference circuit and the negative terminal of each sub-segment LED in the entire LED segment. The output terminal of the constant current driving sub-circuit is connected to the input terminal of the constant current resistor to provide a constant current for each sub-segment LED. The output terminal of the constant current resistor is grounded.

[0025] The gate of the second power switch is connected to the output terminal of the LED constant current judgment circuit, the drain of the second power switch is connected to the thyristor discharge circuit and the constant current drive sub-circuit respectively, and the source of the second power switch is grounded.

[0026] In one possible implementation of the first aspect, the thyristor discharge circuit includes: a discharge resistor, a discharge amplifier, and a discharge power switch, wherein,

[0027] The positive input terminal of the bleeder amplifier is connected to the second output terminal of the wire detection circuit, the negative input terminal of the bleeder amplifier is connected to the input terminal of the bleeder resistor, and the output terminal of the bleeder amplifier is connected to the gate of the bleeder power switch and the drain of the second power switch, respectively.

[0028] The drain of the bleeder power switch is connected to the input terminal of the power output circuit, and the source of the bleeder power switch is connected to the input terminal of the bleeder resistor.

[0029] The output terminal of the bleeder resistor is connected to the input terminal of the constant current resistor.

[0030] In one possible implementation of the first aspect, the constant current drive sub-circuit includes: a plurality of dimming power switches and a plurality of dimming amplifiers, wherein,

[0031] The positive input terminals of the plurality of dimming amplifiers are respectively connected to the output terminals of the corresponding voltage divider resistors in the adaptive dimming reference circuit, the negative input terminals of the plurality of dimming amplifiers are respectively connected to the input terminals of the constant current resistors, and the output terminals of the plurality of dimming amplifiers are respectively connected to the gate of the corresponding dimming power switch and the drain of the second power switch.

[0032] The drains of the plurality of dimming power switches are respectively connected to the negative terminals of the corresponding sub-segments of LEDs, and the sources of the plurality of dimming power switches are respectively connected to the input terminals of the constant current resistors.

[0033] In one possible implementation of the first aspect, the power output circuit includes: an AC power supply, a thyristor, and a rectifier bridge, wherein the thyristor is connected in series between the AC power supply and the rectifier bridge.

[0034] In one possible implementation of the first aspect, the rectifier bridge includes a first diode, a second diode, a third diode, and a fourth diode, wherein,

[0035] The rectifier bridge is composed of a first link consisting of the first diode and the second diode connected in series, and a second link consisting of the third diode and the fourth diode connected in series, connected in parallel.

[0036] The positive terminal of the AC power supply is connected to the input terminal of the thyristor, and the negative terminal of the AC power supply is connected to the cathode terminal of the third diode in the rectifier bridge; the output terminal of the thyristor is connected to the anode terminal of the second diode in the rectifier bridge.

[0037] The anode of the first diode and the anode of the third diode in the rectifier bridge are connected to the output terminal of the LED constant current drive circuit.

[0038] The cathode of the second diode and the cathode of the fourth diode in the rectifier bridge are connected to the positive terminal of the entire LED segment.

[0039] Secondly, embodiments of this application provide a dimming method for a multi-segment light-emitting diode, applied to a dimming circuit for a multi-segment light-emitting diode as described in any of the preceding claims, the method comprising:

[0040] Obtain the line voltage value output by the power supply output circuit and the total voltage difference of the entire LED segment;

[0041] The control signal value of the thyristor is obtained based on the grid voltage value through the LED dimming circuit.

[0042] When the thyristor control signal value is a first control signal value indicating that the grid voltage is tangent by the thyristor, the thyristor discharge circuit in the LED constant current drive circuit is turned on; and,

[0043] The LED dimming circuit obtains a dimming voltage value based on the grid voltage value and the voltage difference of the entire LED segment, so that the current flowing through each sub-segment of the LED segment is adjusted according to the dimming voltage value by the LED constant current driving circuit.

[0044] In one possible implementation of the second aspect, the LED dimming circuit includes a wire mesh detection circuit, an LED lamp pressure detection circuit, and an adaptive dimming reference circuit;

[0045] The process of obtaining the dimming voltage value through the LED dimming circuit based on the grid voltage value and the total voltage difference includes:

[0046] The wire network voltage value is first sampled by the wire network detection circuit to obtain the sampled voltage value;

[0047] The LED lamp voltage detection circuit performs a second sampling process on the voltage difference of the entire LED segment to obtain the entire voltage threshold.

[0048] The adaptive dimming reference circuit performs a linear comparison between the sampled voltage value and the entire voltage threshold.

[0049] If the sampled voltage value is less than the entire voltage threshold, then the output dimming voltage value is the first dimming voltage value;

[0050] If the sampled voltage value is greater than or equal to the entire voltage threshold, then the output dimming voltage value is the second dimming voltage value.

[0051] In one possible implementation of the second aspect, when the thyristor control signal value is the first control signal value and the sampled voltage value is less than the overall voltage threshold, adjusting the current flowing through each sub-segment of the LED in the overall LED segment according to the dimming voltage value via the LED constant current driving circuit includes:

[0052] The negative output terminal of the linear comparator is connected to the gate of the first power switch. The positive output terminal of the linear comparator in the adaptive dimming reference circuit outputs a dimming current, and the dimming voltage value is the first dimming voltage value, so that the current flowing through the entire LED segment changes.

[0053] In one possible implementation of the second aspect, when the thyristor control signal value is the first control signal value and the sampled voltage value is greater than or equal to the overall voltage threshold, the step of adjusting the current flowing through each sub-segment of the LED in the overall LED segment via the LED constant current drive circuit according to the dimming voltage value includes:

[0054] When the negative output terminal of the linear comparator is disconnected from the gate of the first power switch, and the positive output terminal of the linear comparator in the adaptive dimming reference circuit has no dimming current output, the dimming voltage value is the second dimming voltage value, so that the current flowing through the entire LED segment is a constant current.

[0055] In one possible implementation of the second aspect, the method further includes:

[0056] When the control signal value of the thyristor is the second control signal value indicating that the grid voltage is not tangential to the thyristor, the thyristor discharge circuit in the LED constant current drive circuit is turned off; and the negative output terminal of the linear comparator is disconnected from the gate of the first power switch, and there is no dimming current output at the positive output terminal of the linear comparator in the adaptive dimming reference circuit, then the current flowing through the entire LED segment is a constant current.

[0057] In one possible implementation of the second aspect, the method further includes:

[0058] Obtain the judgment result value output by the LED constant current judgment circuit from the power output circuit, wherein the judgment result value is used to characterize whether the voltage flowing through the entire LED segment is less than the total lamp segment voltage value;

[0059] When the judgment result output by the LED constant current judgment circuit is the target result value, the entire LED segment and the thyristor discharge circuit are simultaneously turned off.

[0060] Thirdly, embodiments of this application provide a lighting device, the lighting device including a dimming circuit of a multi-segment light-emitting diode as described in any of the first aspects, the dimming circuit of the multi-segment light-emitting diode performing a dimming method of a multi-segment light-emitting diode as described in any of the second aspects.

[0061] The beneficial effects of the embodiments in this application compared with the prior art are:

[0062] This application provides a dimming circuit for multi-segment light-emitting diodes (LEDs). The circuit includes: a power output circuit, a full-segment LED, an LED dimming circuit, and an LED constant current drive circuit. The full-segment LED comprises multiple sub-segments. The power output circuit, connected to the full-segment LED, provides power to the LED and outputs a grid voltage value. The LED dimming circuit, connected to both the power output circuit and the full-segment LED, samples the grid voltage value and the voltage difference across the entire LED segment, outputting a thyristor control signal value and a dimming voltage value. The LED constant current drive circuit, connected to the LED dimming circuit, each sub-segment LED, and the power output circuit, provides a constant current to each sub-segment LED based on the dimming voltage value and determines whether to turn the thyristor discharge circuit in the LED constant current drive circuit on or off based on the thyristor control signal value. This effectively improves the linearity of low-brightness dimming while maintaining constant luminous flux, high power factor (PF), and low total harmonic distortion (THD) when the thyristor is tangentially at a large angle. Attached Figure Description

[0063] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0064] Figure 1 This is a schematic diagram of the connection structure of a dimming circuit for a multi-segment light-emitting diode provided in an embodiment of this application;

[0065] Figure 2 This is a schematic diagram of the connection structure of a dimming circuit for a multi-segment light-emitting diode provided in another embodiment of this application;

[0066] Figure 3 This is a schematic diagram of the connection structure of a dimming circuit for a multi-segment light-emitting diode provided in another embodiment of this application;

[0067] Figure 4 This is a schematic diagram of the connection structure of an adaptive dimming reference circuit provided in an embodiment of this application;

[0068] Figure 5 This is a schematic diagram of the connection structure of an LED constant current driving circuit according to an embodiment of this application;

[0069] Figure 6 This is a schematic diagram of the connection structure of an LED constant current driving circuit provided in another embodiment of this application;

[0070] Figure 7 This is a schematic flowchart of a dimming method for a multi-segment light-emitting diode provided in an embodiment of this application;

[0071] Figure 8 This is a schematic diagram of the low-brightness dimming result of a dimming circuit for a multi-segment light-emitting diode provided in an embodiment of this application;

[0072] Figure 9 This is a schematic diagram of the structure of a lighting device provided in an embodiment of this application. Detailed Implementation

[0073] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be further described in detail below with reference to the accompanying drawings. The embodiments described with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0074] In the description of this application, it should be understood that the terms "length", "width", "thickness", "top", "bottom", "inner", "outer", "upper", "lower", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0075] To facilitate a clear description of the technical solutions of this application, the terms "first" and "second" are used to distinguish identical or similar items with essentially the same function and effect. Those skilled in the art will understand that the terms "first" and "second" do not limit the quantity or execution order, and that the terms "first" and "second" do not necessarily imply that they are different.

[0076] In this application, unless otherwise expressly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0077] In this application, "and / or" is merely a way of describing the relationship between related objects, indicating that three relationships can exist; for example, A and / or B can represent three cases: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0078] It should be noted that, in this application, the words "in one embodiment," "exemplarily," and "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described in this application as "in one embodiment," "exemplarily," or "for example" should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of words such as "in one embodiment," "exemplarily," and "for example" is intended to present the relevant concepts in a specific manner.

[0079] Please see Figure 1 , Figure 1 This is a schematic diagram of the connection structure of a dimming circuit for a multi-segment light-emitting diode provided in an embodiment of this application. Figure 1 In this circuit, the dimming circuit 1 of the multi-segment light-emitting diode includes: a power output circuit 10, a full-segment light-emitting diode LED 20, an LED dimming circuit 40, and an LED constant current drive circuit 50.

[0080] Specifically, the entire LED segment 20 comprises multiple sub-segments LED20-i (where i represents the sequence number of the sub-segment LED, i = 1, 2, 3, ...). That is, the entire LED segment 20 is composed of multiple sub-segments of LEDs, and each sub-segment of LEDs consists of multiple LED beads. For example... Figure 1In this embodiment, the entire LED segment 20 can include three sub-segments: sub-segment LED20-1, sub-segment LED20-2, and sub-segment LED20-3. Each sub-segment uses multiple LED beads. For example, assuming sub-segment LED20-1 includes eight 9V LED beads, sub-segment LED20-2 includes five 9V LED beads, and sub-segment LED20-3 includes two 9V LED beads, then the entire LED segment 20 includes a total of 15 9V LED beads. In practical applications, the number of sub-segments in the entire LED segment, the number of LED beads in each sub-segment, and the operating voltage of each LED bead can be adjusted according to actual conditions; this embodiment does not impose specific limitations on these aspects.

[0081] Figure 1 In this circuit, the power output circuit 10 is connected to the positive terminal of the entire LED 20 segment, providing power to the entire LED 20 segment and thus outputting the grid voltage value VAC_CUT. The grid voltage value VAC_CUT can be the power supply voltage provided by the power output circuit 10, which is either rectified or tangentially rectified.

[0082] The first input terminal of the LED dimming circuit 40 is connected to the input terminal of the power output circuit 10, and the second input terminal of the LED dimming circuit 40 is connected to the negative terminal of the entire LED 20. This is used to sample the grid voltage value VAC_CUT and the voltage difference V0 of the entire LED 20, outputting the thyristor control signal value V3 and the dimming voltage value Vref, respectively. The first output terminal of the LED dimming circuit 40 is connected to the first input terminal of the LED constant current drive circuit 50, and the second output terminal of the LED dimming circuit 40 is connected to the second input terminal of the LED constant current drive circuit 50, inputting the dimming voltage value Vref and the thyristor control signal value V3 into the LED constant current drive circuit 50, respectively. The voltage difference V0 is the voltage difference between the positive and negative terminals of the entire LED 20. The thyristor control signal value V3 is used to determine whether to turn the thyristor discharge circuit 51 in the LED constant current drive circuit 50 on or off. In other words, when the grid voltage is detected to be tangentially switched by the SCR, the output SCR control signal value V3 is greater than 0, and the SCR discharge circuit 51 in the LED constant current drive circuit 50 is turned on to provide discharge current; when the grid voltage is detected to be untangentially switched by the SCR, the output SCR control signal value V3 is 0, and the SCR discharge circuit 51 in the LED constant current drive circuit 50 is in the off state. The dimming voltage value Vref is used to provide a constant current for each LED segment 20-i, especially when the grid voltage is tangentially switched at a small angle, it can slowly reduce the brightness of the LED segment according to different tangential angles.

[0083] The first input terminal of the LED constant current drive circuit 50 is connected to the first output terminal of the LED dimming circuit 40, acquiring the dimming voltage value Vref output by the LED dimming circuit 40; the second input terminal of the LED constant current drive circuit 50 is connected to the second output terminal of the LED dimming circuit 40, acquiring the thyristor control signal value V3 output by the LED dimming circuit 40; the fourth input terminal of the LED constant current drive circuit 50 is connected to the negative terminal of each sub-segment LED20-i, acquiring the voltage difference value of each sub-segment LED20-i; the output terminal of the LED constant current drive circuit 50 is connected to the output terminal of the power output circuit 10. The fourth input terminal of the LED constant current drive circuit 50 includes multiple interfaces, which can be connected to multiple segments of LED20-i respectively. Figure 1 In the circuit, the voltage value corresponding to the negative terminal of sub-segment LED20-1 is V_LED1, the voltage value corresponding to the negative terminal of sub-segment LED20-2 is V_LED2, and the voltage value corresponding to the negative terminal of sub-segment LED20-3 is V_LED3, which are respectively connected to the corresponding ports in the fourth input terminal of the LED constant current drive circuit 50.

[0084] The LED constant current drive circuit 50 provides a constant current to each sub-segment LED 20-i based on the dimming voltage value output by the LED dimming circuit 40, and determines whether to turn on or off the thyristor discharge circuit 51 in the LED constant current drive circuit 50 based on the thyristor control signal value output by the LED dimming circuit 40.

[0085] It is understood that the dimming circuit of the multi-segment light-emitting diode provided in the embodiments of this application can effectively improve the linearity of low-brightness dimming while ensuring constant luminous flux, high power factor (PF), and low total harmonic distortion (THD) when the silicon controlled rectifier is tangentially at a large angle.

[0086] In one possible implementation, such as Figure 2 As shown, Figure 2 This is a schematic diagram of the connection structure of a dimming circuit for a multi-segment light-emitting diode provided in another embodiment of this application. Figure 2 In the dimming circuit 1 of the multi-segment light-emitting diodes, there is also an LED constant current judgment circuit 30.

[0087] Specifically, the input terminal of the LED constant current judgment circuit 30 is connected to the negative terminal of the entire LED 20, and the output terminal of the LED constant current judgment circuit 30 is connected to the third input terminal of the LED constant current drive circuit 50. This circuit determines whether the voltage flowing through the entire LED 20 is less than the total lamp segment voltage and outputs a judgment result value V4. The third input terminal of the LED constant current drive circuit 50 is connected to the output terminal of the LED constant current judgment circuit 30, and the judgment result value V4 output by the LED constant current judgment circuit 30 is collected. The LED constant current drive circuit 50 can determine whether to simultaneously turn off the SCR discharge circuit and the entire LED 20 based on the judgment result value output by the LED constant current judgment circuit 30. It should be noted that when the voltage difference V0 across the entire LED 20 is less than the required total lamp segment voltage, the judgment result value V4 is the target result value. In this case, the grid voltage is tangentially oriented at a small angle, causing the entire LED 20 and the SCR discharge circuit 51 to turn off simultaneously. The total segment voltage value refers to the minimum voltage required to light up all the LEDs in the entire LED segment 20. Here, the target result value can be either high or low, depending on the actual logic circuit.

[0088] It is understood that the dimming circuit of the multi-segment light-emitting diode provided in the embodiments of this application can not only effectively improve the linearity of low-brightness dimming, but also effectively improve the uniformity of the surface light source, while ensuring that the luminous flux is constant, the power factor (PF) is high and the total harmonic distortion (THD) is low when the silicon controlled rectifier is tangential at a large angle.

[0089] In one possible implementation, such as Figure 3 As shown, Figure 3 This is a schematic diagram of the connection structure of a dimming circuit for a multi-segment light-emitting diode provided in another embodiment of this application. Figure 3 In the LED dimming circuit 40, there are: a wire mesh detection circuit 41, an LED lamp voltage detection circuit 42, and an adaptive dimming reference circuit 43. The wire mesh detection circuit 41 is connected to the input terminal of the power output circuit 10. It is used to perform a first sampling process on the wire mesh voltage value VAC_CUT, output the sampled voltage value V2, and determine whether the wire mesh voltage is tangent by the thyristor based on the wire mesh voltage value VAC_CUT, and output the thyristor control signal value V3.

[0090] The LED lamp voltage detection circuit 42 is connected to the input terminal of the power output circuit 10 and the negative terminal of the entire LED 20, respectively. It is used to perform a second sampling process on the voltage difference V0 of the entire LED 20 and output the voltage threshold V1 of the entire segment.

[0091] The adaptive dimming reference circuit 43 is connected to the LED lamp pressure detection circuit 42 and the wire mesh detection circuit 41 respectively. It is used to perform a linear comparison between the sampling voltage V2 output by the wire mesh detection circuit 41 and the full-segment voltage threshold V1 output by the LED lamp pressure detection circuit 42, and output the dimming voltage value Vref.

[0092] Specifically, Figure 3 In the LED dimming circuit 40, there are wire mesh detection circuit 41, LED lamp pressure detection circuit 42 and adaptive dimming reference circuit 43.

[0093] The input terminal of the wire mesh detection circuit 41 is connected to the input terminal of the power output circuit 10. The second output terminal of the wire mesh detection circuit 41 (i.e., the second output terminal of the dimming circuit 40) is connected to the second input terminal of the LED constant current drive circuit. Based on the sampled wire mesh voltage value VAC_CUT, it determines whether the wire mesh voltage is directional by the thyristor and outputs the thyristor control signal value V3. The first output terminal of the wire mesh detection circuit 41 is connected to the first input terminal of the adaptive dimming reference circuit 43. It performs a first sampling process on the sampled wire mesh voltage value VAC_CUT and outputs a sampled voltage value V2. This sampled voltage value V2 is the input value of the adaptive dimming reference circuit 43.

[0094] It should be noted that when the grid voltage is detected to be shunted by the thyristor, the output thyristor control signal value V3 is greater than 0, and the thyristor discharge circuit 51 in the LED constant current drive circuit 50 is turned on to provide over-discharge current; when the grid voltage is detected not to be shunted by the thyristor, the output thyristor control signal value V3 is 0, and the thyristor discharge circuit 51 in the LED constant current drive circuit 50 is in the closed state.

[0095] The first input terminal of the LED lamp voltage detection circuit 42 (i.e., the first input terminal of the dimming circuit 40) is connected to the power input terminal of the power output circuit 10. The second input terminal of the LED lamp voltage detection circuit 42 (i.e., the second input terminal of the dimming circuit 40) is connected to the negative terminal of the entire LED 20. The output terminal of the LED lamp voltage detection circuit 42 is connected to the second input terminal of the adaptive dimming reference circuit 43. This circuit is used to perform a second sampling process on the entire voltage difference V0 of the entire LED 20, i.e., to detect the lamp segment voltage difference of the entire LED 20 connected to the system, thereby outputting different voltages to obtain the entire voltage threshold V1. This entire voltage threshold V1 is used as the threshold voltage for adjusting the dimming voltage value Vref and is input to the second input terminal of the adaptive dimming reference circuit 43.

[0096] It should be noted that when sampling the grid voltage, peak sampling and average sampling methods can be used. The first sampling process is a method of processing the sampled grid voltage value VAC_CUT to obtain the sampled voltage value V2. The second sampling process is a method of processing the sampled total LED voltage difference V0 to obtain the total voltage threshold V1. In this embodiment, the specific processing procedures of the first and second sampling processes are not limited, as long as the corresponding sampled voltage value V2 and total voltage threshold V1 are obtained.

[0097] The second input terminal of the adaptive dimming reference circuit 43 is connected to the output terminal of the LED lamp voltage detection circuit 42 to acquire the entire voltage threshold V1 output by the LED lamp voltage detection circuit 42; the first input terminal of the adaptive dimming reference circuit 43 is connected to the first output terminal of the wire mesh detection circuit 41 to acquire the sampled voltage value V2 output by the wire mesh detection circuit 41; and the sampled voltage value V2 and the entire voltage threshold V1 are linearly compared to output the dimming voltage value Vref; the output terminal of the adaptive dimming reference circuit 43 (i.e. the first output terminal of the dimming circuit 40) is connected to the first input terminal of the LED constant current drive circuit 50 to input the dimming voltage value Vref into the LED constant current drive circuit 50, thereby changing the input reference value of the LED constant current drive circuit 50. Especially when the wire mesh voltage is tangentially oriented at a small angle, it can slowly reduce the brightness of different LED segments according to different tangential angles.

[0098] For example, Figure 3 The circuit also includes a constant current resistor R6, through which the LED constant current drive circuit 50 is connected to the power output circuit. The output terminal of the constant current resistor R6 is grounded.

[0099] It should be noted that when the SCR control signal value V3 is 0, it indicates that the line voltage value VAC_CUT is not oriented by the SCR. When the SCR control signal value V3 is greater than 0, it indicates that the line voltage value VAC_CUT is oriented by the SCR. In this case, if the sampled voltage value V2 is less than the entire voltage threshold V1, it indicates that the line voltage value VAC_CUT is oriented at a small angle; if the sampled voltage value V2 is greater than or equal to the entire voltage threshold V1, it indicates that the line voltage value VAC_CUT is oriented at a large angle.

[0100] In one possible implementation, such as Figure 4 As shown, Figure 4 This is a schematic diagram of the connection structure of an adaptive dimming reference circuit provided in an embodiment of this application. Figure 4In the adaptive dimming reference circuit 43, there are: a linear comparator C1, a first power switch NMOS1, a first resistor R5, a second resistor R0 and multiple voltage divider resistors Rj (j represents the serial number of the voltage divider resistor, j = 1, 2, 3...).

[0101] The positive input terminal of linear comparator C1 is connected to the first output terminal of the wire detection circuit 41, and the negative input terminal of linear comparator C1 is connected to the output terminal of the LED lamp voltage detection circuit 42. It is used to perform linear comparison between the sampled voltage value V2 and the whole voltage threshold V1, and output the dimming current I1. The positive output terminal of linear comparator C1 is connected to the drain of the first power switch NMOS1 through the first resistor R5, and the negative output terminal of linear comparator C1 is connected to the gate of the first power switch NMOS1. The source of the first power switch NMOS1 is grounded. The input terminal of the first resistor R5 is connected to the clamping voltage VQ. The output terminal of the first resistor R5 is grounded after passing through the link formed by the second resistor R0 and multiple voltage divider resistors Rj in series. The output terminals of the multiple voltage divider resistors Rj are respectively connected to the LED constant current driving circuit, and the multiple dimming voltage values ​​Vref output by the multiple voltage divider resistors Rj are respectively input to the LED constant current driving circuit 50.

[0102] Following the example above, such as Figure 4 In the diagram, each of the three sub-segments LED20-i (i.e., sub-segment LED20-1, sub-segment LED20-2, and sub-segment LED20-3) corresponds to a voltage divider resistor Rj (i.e., voltage divider resistor R1, voltage divider resistor R2, and voltage divider resistor R3), and the corresponding dimming voltage values ​​are Vref1, Vref2, and Vref3. The sampled voltage value V2 and the overall voltage threshold V1 serve as the positive and negative input terminals of the linear comparator C1, respectively connected to the grid detection circuit 41 and the LED lamp voltage detection circuit 42. The dimming current I1 flows entirely through the first resistor R5 and the first power switch NMOS1 to ground only when the sampled voltage value V2 is less than the overall voltage threshold V1; when the sampled voltage value V2 is greater than or equal to the overall voltage threshold V1, there is no dimming current I1. Similarly, the bias voltage Vbn is connected to the gate of the first power switch NMOS1 only when the sampled voltage value V2 is less than the overall voltage threshold V1, providing a bias voltage; when the sampled voltage value V2 is less than the overall voltage threshold V1, Vbn is 0.

[0103] The clamping voltage VQ is a fixed voltage. When the dimming current I1 flows through the first resistor R5, the dimming voltage values ​​Vref1, Vref2, and Vref3 decrease sequentially according to the voltage divider resistors R1, R2, and R3. The dimming voltage values ​​Vref1, Vref2, and Vref3 are then connected to the LED constant current drive circuit 50, and the current flowing through the constant current resistor R6 is Vref3 / R6 (or Vref2 / R6, Vref1 / R6).

[0104] In one possible implementation, such as Figure 4 As shown, the number of voltage divider resistors Rj is the same as the number of sub-segments LED20-i in the entire LED 20 segment, and each voltage divider resistor Rj corresponds one-to-one with a sub-segment LED20-i. By dividing the dimming current through the voltage divider resistors Rj, the dimming voltage value Vref for different sub-segments LED20-i is obtained, thereby gradually reducing the brightness of the LED segment.

[0105] In one possible implementation, such as Figure 5 As shown, Figure 5 This is a schematic diagram of the connection structure of an LED constant current driving circuit provided in an embodiment of this application. Figure 5 In the LED constant current drive circuit 50, there are: a second power switch NMOS2, a thyristor discharge circuit 51, and a constant current drive sub-circuit 52.

[0106] The input terminal of the thyristor discharge circuit 51 is connected to the second output terminal of the wire detection circuit 41, and the output terminal of the thyristor discharge circuit 51 is connected to the input terminal of the constant current resistor R6. This is used to judge the thyristor control signal value V3 and determine whether to turn the thyristor discharge circuit 51 on or off. The input terminal of the constant current drive sub-circuit 52 is connected to the output terminals of multiple voltage divider resistors Rj in the adaptive dimming reference circuit 43 and the negative terminal of each sub-segment LED20-i in the entire LED 20. The output terminal of the constant current drive sub-circuit 52 is connected to the input terminal of the constant current resistor R6, providing a constant current for each sub-segment LED20-i. The output terminal of the constant current resistor R6 is grounded. The gate of the second power switch NMOS2 is connected to the output terminal of the LED constant current judgment circuit 30, acquiring the judgment result value V4 output by the LED constant current judgment circuit 30. The drain of the second power switch NMOS2 is connected to the thyristor discharge circuit 51 and the constant current drive sub-circuit 52, and the source of the second power switch NMOS2 is grounded.

[0107] In one possible implementation, such as Figure 6 As shown, Figure 6 This is a schematic diagram of the connection structure of an LED constant current driving circuit provided in another embodiment of this application. Figure 6 In the circuit 51, the thyristor discharge circuit includes: discharge resistor R7, discharge amplifier AMP1, and discharge power switch NMOS3.

[0108] The positive input terminal of the bleeder amplifier AMP1 is connected to the second output terminal of the wire detection circuit 41 (i.e., the second output terminal of the dimming circuit 40) to acquire the thyristor control signal value V3 output by the wire detection circuit 41; the negative input terminal of the bleeder amplifier AMP1 is connected to the input terminal of the bleeder resistor R7; the output terminal of the bleeder amplifier AMP1 is connected to the gate of the bleeder power switch NMOS3 and the drain of the second power switch NMOS2 respectively; the drain of the bleeder power switch NMOS3 is connected to the input terminal of the power output circuit 10 to acquire the wire voltage value VAC_CUT); the source of the bleeder power switch NMOS3 is connected to the input terminal of the bleeder resistor R7; and the output terminal of the bleeder resistor R7 is connected to the input terminal of the constant current resistor R6.

[0109] When the grid voltage is detected to be switched by the thyristor, the output thyristor control signal value V3 is greater than 0. The output terminal of the bleeder amplifier AMP1 is connected to the gate of the bleeder power switch NMOS3, and current flows through the bleeder resistor R7, thus turning on the thyristor bleeder circuit 51 and providing bleeder current. When the grid voltage is detected not to be switched by the thyristor, the output thyristor control signal value V3 is 0. The output terminal of the bleeder amplifier AMP1 is disconnected from the gate of the bleeder power switch NMOS3, and no current flows through the bleeder resistor R7, thus the thyristor bleeder circuit 51 is in the off state.

[0110] In one possible implementation, such as Figure 6 In the constant current drive sub-circuit 52, there are multiple dimming power switches NMOS-Tm (Tm represents the serial number of the dimming power switch, m = 1, 2, 3...) and multiple dimming amplifiers AMP-Tn (Tn represents the serial number of the dimming amplifier, n = 1, 2, 3...). The positive input terminals of the multiple dimming amplifiers AMP-Tn are connected to the output terminals of the corresponding voltage divider resistors Rj in the adaptive dimming reference circuit 43, the negative input terminals of the multiple dimming amplifiers AMP-Tn are connected to the input terminals of the constant current resistor R6, and the output terminals of the multiple dimming amplifiers AMP-Tn are connected to the gate of the corresponding dimming power switch NMOS-Tm and the drain of the second power switch NMOS2, respectively. The drains of the multiple dimming power switches NMOS-Tm are connected to the negative terminals of the corresponding sub-segments LED20-i, and the sources of the multiple dimming power switches NMOS-Tm are connected to the input terminals of the constant current resistor R6.

[0111] Following the example above, Figure 6In the constant current drive sub-circuit 52, there are three dimming power switches, namely dimming power switches NMOS-T1, NMOS-T2, and NMOS-T3, and three dimming amplifiers, namely dimming amplifier AMP-T1, AMP-T2, and AMP-T3. The positive input terminal of the dimming amplifier AMP-T1 is connected to the output terminal of the corresponding voltage divider resistor R1 in the adaptive dimming reference circuit 43 to acquire the dimming voltage value Vref1. The negative input terminal of the dimming amplifier AMP-T1 is connected to the input terminal of the constant current resistor R6. The output terminal of the dimming amplifier AMP-T1 is connected to the gate of the dimming power switch NMOS-T1 and the drain of the second power switch NMOS2, respectively. The drain of the dimming power switch NMOS-T1 is connected to the negative terminal of the corresponding sub-segment LED20-1 to acquire the voltage value V_LED1 at the negative terminal of the sub-segment LED20-1. The source of the dimming power switch NMOS-T1 is connected to the input terminal of the constant current resistor R6.

[0112] Correspondingly, the positive input terminal of the dimming amplifier AMP-T2 is connected to the output terminal of the corresponding voltage divider resistor R2 in the adaptive dimming reference circuit 43 to acquire the dimming voltage value Vref2. The negative input terminal of the dimming amplifier AMP-T2 is connected to the input terminal of the constant current resistor R6. The output terminal of the dimming amplifier AMP-T2 is connected to the gate of the dimming power switch NMOS-T2 and the drain of the second power switch NMOS2, respectively. The drain of the dimming power switch NMOS-T2 is connected to the negative terminal of the corresponding sub-segment LED20-2 to acquire the voltage value V_LED2 at the negative terminal of the sub-segment LED20-2. The source of the dimming power switch NMOS-T2 is connected to the input terminal of the constant current resistor R6.

[0113] Correspondingly, the positive input terminal of the dimming amplifier AMP-T3 is connected to the output terminal of the corresponding voltage divider resistor R3 in the adaptive dimming reference circuit 43 to acquire the dimming voltage value Vref3. The negative input terminal of the dimming amplifier AMP-T3 is connected to the input terminal of the constant current resistor R6. The output terminal of the dimming amplifier AMP-T3 is connected to the gate of the dimming power switch NMOS-T3 and the drain of the second power switch NMOS2, respectively. The drain of the dimming power switch NMOS-T3 is connected to the negative terminal of the corresponding sub-segment LED20-3 to acquire the voltage value V_LED3 at the negative terminal of the sub-segment LED20-3. The source of the dimming power switch NMOS-T3 is connected to the input terminal of the constant current resistor R6. At this time, the current flowing through the constant current resistor R6 is Vref3 / R6 (or Vref2 / R6, Vref1 / R6).

[0114] It should be noted that when the voltage difference V0 of the entire LED 20 is less than the total lamp segment voltage required by the entire LED 20, that is, the grid voltage and current are insufficient to maintain the constant current of the entire LED segment, the judgment result value V4 is the target result value. At this time, the gate of the second power switch is disconnected, and the output current of the discharge amplifier AMP1, the dimming amplifier AMP-T1, the dimming amplifier AMP-T2 and the dimming amplifier AMP-T3 will be directly grounded, thus turning off the entire LED 20 and the thyristor discharge circuit 51 at the same time.

[0115] In one possible implementation, such as Figure 1 As shown, Figure 1 In the circuit, the power output circuit 10 includes: an AC power supply AC, a silicon controlled rectifier 11 (SCR) 11, and a rectifier bridge, wherein the SCR 11 is connected in series between the AC power supply AC and the rectifier bridge.

[0116] Specifically, the rectifier bridge includes a first diode D1, a second diode D2, a third diode D3, and a fourth diode D4. The rectifier bridge is formed by connecting a first link (consisting of the first diode D1 and the second diode D2 in series) and a second link (consisting of the third diode D3 and the fourth diode D4 in series) in parallel. The positive terminal of the AC power supply is connected to the input terminal of the thyristor 11, and the negative terminal of the AC power supply is connected to the cathode terminal of the third diode D3 in the rectifier bridge. The output terminal of the thyristor 11 is connected to the anode terminal of the second diode D2 in the rectifier bridge. The anode terminals of the first diode D1 and the third diode D3 in the rectifier bridge are connected to the output terminal of the LED constant current drive circuit 50. The cathode terminals of the second diode D2 and the fourth diode D4 in the rectifier bridge are connected to the positive terminal of the entire LED 20.

[0117] It should be understood that a rectifier bridge converts alternating current (AC) to direct current (DC), providing a stable DC power supply for electronic equipment (LED segments). A silicon controlled rectifier (SCR) is used to regulate the output voltage and current to reduce power loss in the power supply, increase output power, and extend the lifespan of the equipment.

[0118] A dimming circuit for a multi-segment light-emitting diode corresponding to the above embodiment, Figure 7 This diagram illustrates a dimming method for a multi-segment light-emitting diode according to an embodiment of this application. For ease of explanation, only the parts relevant to the embodiment of this application are shown. (Refer to...) Figure 7 The dimming method for multi-segment light-emitting diodes in this embodiment is applied to a dimming circuit for multi-segment light-emitting diodes as described in any of the above claims. The dimming method for multi-segment light-emitting diodes includes:

[0119] S11. Obtain the line voltage value output by the power output circuit and the voltage difference of the entire LED segment.

[0120] S12. The control signal value of the thyristor is obtained through the LED dimming circuit based on the line voltage value.

[0121] S13. When the thyristor control signal value is the first control signal value indicating that the grid voltage is tangent by the thyristor, the thyristor discharge circuit in the LED constant current drive circuit is turned on; and, through the LED dimming circuit, the dimming voltage value is obtained according to the grid voltage value and the voltage difference of the whole segment, so that the current flowing through each sub-segment of LED in the whole segment is adjusted according to the dimming voltage value through the LED constant current drive circuit.

[0122] It should be noted that this method is applied to the dimming circuit of the aforementioned multi-segment LED.

[0123] In step S11, combined Figure 1 It can be seen that the grid voltage value VAC_CUT is the power supply voltage provided by the power output circuit 10, which is the power supply voltage after rectification or tangential switching in this circuit. The total voltage difference V0 is the voltage difference between the positive and negative terminals of the entire LED 20.

[0124] In step S12, the grid voltage value is input to the LED dimming circuit 40. After processing by the LED dimming circuit 40, the thyristor control signal value V3 is obtained. The thyristor control signal value V3 is used to determine whether the thyristor discharge circuit 51 in the LED constant current drive circuit 50 is turned on or off. That is, when the grid voltage is detected to be switched by the thyristor, the output thyristor control signal value V3 is greater than 0, and the thyristor discharge circuit in the LED constant current drive circuit is turned on to provide discharge current; when the grid voltage is not detected to be switched by the thyristor, the output thyristor control signal value V3 is 0, and the thyristor discharge circuit in the LED constant current drive circuit is in the off state.

[0125] In step S13, the first control signal value indicates that the grid voltage is shunted by the thyristor. In this embodiment, the first control signal value is a value greater than 0. When the thyristor control signal value V3 is the first control signal value, that is, the thyristor control signal value V3 is greater than 0, it indicates that the grid voltage is shunted by the thyristor. At this time, the thyristor discharge circuit in the LED constant current drive circuit is turned on to provide discharge current. Then, the grid voltage value VAC_CUT and the total voltage difference V0 are input to the LED dimming circuit 40. The LED dimming circuit 40 processes and outputs the dimming voltage value Vref. Then, according to the dimming voltage value Vref, the LED constant current drive circuit 50 controls the current flowing through each sub-segment of LED in the entire LED 20 (e.g., ...). Figure 1 In the middle, the current of sub-segment LED20-1, sub-segment LED20-2, and sub-segment LED20-3 is adjusted.

[0126] In one possible implementation, the method further includes:

[0127] The judgment result value output by the LED constant current judgment circuit is obtained from the power output circuit, wherein the judgment result value is used to characterize whether the voltage flowing through the entire LED segment is less than the total lamp segment voltage value.

[0128] When the judgment result output by the LED constant current judgment circuit is the target result value, the entire LED segment and the thyristor discharge circuit are simultaneously turned off.

[0129] Combination Figure 2 As shown, the judgment result value V4 is used to determine whether the voltage flowing through the entire LED segment is less than the total LED segment voltage value. It is the output value of the LED constant current judgment circuit. The total LED segment voltage value refers to the minimum voltage value required to light all LEDs in the entire LED segment 20. The target result value indicates that the voltage difference V0 across the entire LED segment 20 is less than the total LED segment voltage value required for the entire LED segment 20. The total LED segment voltage value refers to the minimum voltage value required to light all LEDs in the entire LED segment 20.

[0130] In this embodiment, the determination result value V4 is either the target result value or a non-target result value. In some examples, the target result value may correspond to a high level, and the non-target result value may correspond to a low level; in other examples, the target result value may correspond to a low level, and the non-target result value may correspond to a high level. Whether the target result value corresponds to a high level or a low level is specifically determined according to the required logic circuit. Continuing with the above examples, such as... Figure 1 In the example, the entire LED 20 segment comprises 15 9V LED beads, resulting in a total segment voltage of 135V. In practical applications, the total segment voltage of the entire LED 20 segment can be other values. Specifically, the total segment voltage of the entire LED 20 segment can be determined based on the number of LEDs in each segment, the number of LED beads in each segment, and the operating voltage of each LED bead.

[0131] When the voltage difference V0 of the entire LED 20 is less than the total lamp segment voltage required by the entire LED 20, the judgment result value V4 output by the LED constant current judgment circuit 30 is the target result value. At this time, the grid voltage is tangent to a small angle, which will cause the entire LED 20 and the thyristor discharge circuit 51 to be turned off at the same time.

[0132] It is understood that this application provides a dimming method for multi-segment LEDs, which involves acquiring the grid voltage value output by the power output circuit, the voltage difference of the entire LED segment, and the judgment result value output by the LED constant current judgment circuit. The judgment result value indicates whether the voltage flowing through the entire LED segment is less than the total segment voltage. The LED dimming circuit obtains a thyristor control signal value based on the grid voltage value. When the thyristor control signal value is a first control signal value indicating that the grid voltage is shunted by the thyristor, the thyristor discharge circuit in the LED constant current drive circuit is turned on. Furthermore, the LED dimming circuit obtains a dimming voltage value based on the grid voltage value and the voltage difference of the entire segment, so that the current flowing through each sub-segment of the LED segment is adjusted according to the dimming voltage value by the LED constant current drive circuit. The entire LED segment and the thyristor discharge circuit are simultaneously turned off when the judgment result value output by the LED constant current judgment circuit is the target result value. When the grid voltage is tangent at a small angle, the dimming voltage value of the LED driver constant current is adaptively and linearly adjusted by this method. When the grid voltage value and current are detected to be insufficient to maintain the constant current, the entire LED segment is turned off, achieving the effect of simultaneous brightening and dimming of LEDs. This effectively improves the linearity of low-brightness dimming and the uniformity of the surface light source, and also has high integration and low cost.

[0133] In one possible implementation, the LED dimming circuit 40 includes a wire mesh detection circuit 41, an LED lamp voltage detection circuit 42, and an adaptive dimming reference circuit 43; the LED dimming circuit 40 obtains the dimming voltage value Vref based on the wire mesh voltage value VAC_CUT and the total voltage difference V0, including:

[0134] The wire network voltage value VAC_CUT is sampled by the wire network detection circuit 41 to obtain the sampled voltage value V2.

[0135] The LED lamp voltage detection circuit 42 performs a second sampling process on the voltage difference V0 of the entire LED segment to obtain the voltage threshold V1 of the entire segment.

[0136] The adaptive dimming reference circuit 43 performs a linear comparison between the sampled voltage value V2 and the total voltage threshold V1.

[0137] If the sampled voltage value V2 is less than the entire voltage threshold V1, then the output dimming voltage value Vref is the first dimming voltage value.

[0138] If the sampled voltage value V2 is greater than or equal to the entire voltage threshold V1, then the output dimming voltage value Vref is the second dimming voltage value.

[0139] It should be noted that the sampled voltage value V2 is obtained by performing a first sampling process on the sampled network voltage value VAC_CUT by the network detection circuit 41. The total voltage threshold V1 is obtained by performing a second sampling process on the total voltage difference V0 of the entire LED segment by the LED lamp voltage detection circuit 42. In this embodiment, the specific processing procedures of the first and second sampling processes are not limited, as long as the corresponding sampled voltage value V2 and total voltage threshold V1 can be obtained.

[0140] The dimming voltage value Vref is the value output by the adaptive dimming reference circuit 43 after linearly comparing the sampled voltage value V2 with the overall voltage threshold V1. The dimming voltage value Vref is either a first dimming voltage value or a second dimming voltage value. When the sampled voltage value V2 is less than the overall voltage threshold V1, the dimming voltage value Vref output by the adaptive dimming reference circuit 43 is the first dimming voltage value; when the sampled voltage value V2 is greater than or equal to the overall voltage threshold V1, the dimming voltage value Vref output by the adaptive dimming reference circuit 43 is the second dimming voltage value.

[0141] Specifically, when the thyristor control signal value V3 is the first control signal value and the sampled voltage value V2 is less than the entire voltage threshold V1, the thyristor control signal value V3 is greater than 0 and the grid voltage value VAC_CUT is tangent to a small angle by the thyristor. At this time, the negative output terminal of the linear comparator C1 is connected to the gate of the first power switch NMOS1, and the positive output terminal of the linear comparator C1 in the adaptive dimming reference circuit 43 outputs a dimming current I1. Then the dimming voltage value Vref is the first dimming voltage value, so that the current flowing through the entire LED 20 changes.

[0142] When the thyristor control signal value V3 is the first control signal value and the sampled voltage value V2 is greater than or equal to the entire voltage threshold V1, the thyristor control signal value V3 is greater than 0 and the grid voltage value VAC_CUT is tangent to a large angle by the thyristor. At this time, the negative output terminal of the linear comparator C1 is disconnected from the gate of the first power switch NMOS1, and there is no dimming current I1 output at the positive output terminal of the linear comparator C1 in the adaptive dimming reference circuit 43. Then the dimming voltage value Vref is the second dimming voltage value, so that the current flowing through the entire LED 20 is a constant current.

[0143] In one possible implementation, the dimming method for the multi-segment LED further includes:

[0144] When the thyristor control signal value V3 is the second control signal value indicating that the grid voltage is not tangent by the thyristor, that is, when the thyristor control signal value V3 is 0, the grid voltage value VAC_CUT is not tangent by the thyristor, the thyristor discharge circuit 51 in the LED constant current drive circuit 50 is turned off; and the negative output terminal of the linear comparator C1 is disconnected from the gate of the first power switch NMOS1, and there is no dimming current I1 output at the positive output terminal of the linear comparator C1 in the adaptive dimming reference circuit 43, then the current flowing through the entire LED 20 is a constant current.

[0145] In a specific embodiment, such as Figure 3 When the thyristor control signal value V3 is 0, it indicates that the line voltage value VAC_CUT is not tangent by the thyristor. At this time, the output full-segment voltage threshold V1 is fixed, no current flows through the discharge resistor R7, the thyristor discharge circuit 51 is closed, the sampled voltage value V2 is greater than the full-segment voltage threshold V1, the dimming voltage values ​​Vref1, Vref2, and Vref3 are fixed values, and the current flowing through the full LED is fixed.

[0146] When the SCR control signal value V3 is greater than 0, it indicates that the grid voltage value VAC_CUT is tangent by the SCR. At this time, current flows through the discharge resistor R7, and the SCR discharge circuit 51 is turned on. If the grid voltage value VAC_CUT is tangent at a large angle, and the sampled voltage value V2 is greater than or equal to the entire voltage threshold V1, then the dimming voltage values ​​Vref1, Vref2, and Vref3 are fixed values, and the current flowing through the entire LED is fixed.

[0147] When the SCR control signal value V3 is greater than 0, it indicates that the grid voltage value VAC_CUT is tangent by the SCR. At this time, current flows through the discharge resistor R7, and the SCR discharge circuit 51 is turned on. If the grid voltage value VAC_CUT is tangent at a small angle, and the sampled voltage value V2 is less than the overall voltage threshold V1, then the dimming voltage values ​​Vref1, Vref2, and Vref3 are variable values. The dimming current I1 is adjusted according to different sampled voltage values ​​V2 to change the dimming voltage values ​​Vref1, Vref2, and Vref3. Until the judgment result value V4 is the target result value (i.e., high level), it indicates that the cycle of the grid voltage value VAC_CUT has ended, and all LED segments are turned off, visually achieving the effect of linear dimming and simultaneous extinguishing of LED segments. For this situation, continuing from the above example, as follows... Figure 8 As shown, Figure 8 This is a schematic diagram of the low-brightness dimming result of a dimming circuit for a multi-segment light-emitting diode provided in an embodiment of this application.

[0148] Figure 8 The schematic diagram of the low-brightness dimming result of the multi-segment LED described in the figure corresponds to... Figure 3 The dimming circuit of the multi-segment light-emitting diodes described herein, Figure 3 In this example, the entire LED segment comprises three sub-segments, with a total of 15 9V LED beads. Therefore, the total segment voltage is 135V. Assuming the grid voltage VAC_CUT is switched to 145V, Vref3 is adjusted to Vref3_1, and the current I_R6 flowing through the constant current resistor R6 is Vref3_1 / R6. If the grid voltage VAC_CUT is switched to a lower 140V, Vref3 is adjusted to a smaller Vref3_2, and the current I_R6 flowing through the constant current resistor R6 also becomes Vref3_2 / R6. This process achieves low-brightness linear dimming, and in each cycle, when the total segment voltage is less than 135V, a simultaneous shutdown effect is achieved.

[0149] It should be understood that the dimming circuit for a multi-segment LED provided in this application can adjust the driving current of the entire LED segment based on whether the grid voltage is tangent by the thyristor and the tangent angle by detecting the voltage difference of the LED segments in the externally connected circuit. When the grid voltage is not tangent, the entire LED segment is driven by a constant current normally; when the grid voltage is tangent at a large angle, the thyristor discharge circuit is periodically turned off without affecting the constant current drive, thereby improving efficiency; when the grid voltage is tangent at a small angle, the dimming voltage value of the LED driving constant current is adaptively and linearly adjusted, and when the grid voltage value and current are detected to be insufficient to maintain the constant current, the entire LED segment is turned off, achieving the effect of simultaneous brightening and dimming of the LEDs, effectively improving the linearity of low-brightness dimming and the uniformity of the surface light source, and also has high integration and low cost.

[0150] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0151] A dimming method for a multi-segment light-emitting diode corresponding to the above embodiment, Figure 9 A schematic diagram of a lighting device according to an embodiment of this application is shown. For ease of explanation, only the parts relevant to the embodiment of this application are shown. (Refer to...) Figure 9 The lighting device 3 of this embodiment includes a dimming circuit 1 for a multi-segment light-emitting diode as described in any of the above embodiments. The dimming circuit 1 for the multi-segment light-emitting diode performs the steps described in the dimming method embodiments of the various multi-segment light-emitting diodes described above.

[0152] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments of this application can be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. A computer-readable medium can include at least: any entity or device capable of carrying computer program code to a photographic device / terminal device, a recording medium, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium. Examples include USB flash drives, portable hard drives, magnetic disks, or optical disks. In some jurisdictions, according to legislation and patent practice, computer-readable media cannot be electrical carrier signals or telecommunication signals.

[0153] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0154] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0155] In the embodiments provided in this application, it should be understood that the disclosed apparatus / network devices and methods can be implemented in other ways. For example, the apparatus / network device embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0156] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0157] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions 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 this application, and should all be included within the protection scope of this application.

Claims

1. A dimming circuit for a multi-segment light-emitting diode, characterized in that, The circuit includes: a power output circuit, a complete LED assembly, an LED dimming circuit, and an LED constant current drive circuit. A complete LED segment consists of multiple sub-segments of LEDs; The power output circuit is connected to the entire LED segment and is used to provide power to the entire LED segment and output the grid voltage value. The LED dimming circuit is connected to the power output circuit and the entire LED segment respectively, and is used to sample the grid voltage value and the voltage difference of the entire LED segment, and output the thyristor control signal value and the dimming voltage value respectively. The LED constant current driving circuit is connected to the LED dimming circuit, each of the sub-segments of LED, and the power output circuit, respectively. It is used to provide a constant current to each of the sub-segments of LED according to the dimming voltage value, and to determine whether to turn on or off the thyristor discharge circuit in the LED constant current driving circuit according to the thyristor control signal value.

2. The dimming circuit for a multi-segment light-emitting diode as described in claim 1, characterized in that, The circuit further includes: an LED constant current detection circuit, wherein... The LED constant current judgment circuit is connected to the negative terminal of the entire LED segment and is used to determine whether the voltage flowing through the entire LED segment is less than the total lamp segment voltage value, and output the judgment result value. The LED constant current driving circuit is also connected to the LED constant current judgment circuit, and is also used to determine whether to turn off the thyristor discharge circuit and the entire LED segment simultaneously based on the judgment result value.

3. The dimming circuit for a multi-segment light-emitting diode as described in claim 2, characterized in that, The LED dimming circuit includes: a wire mesh detection circuit, an LED lamp voltage detection circuit, and an adaptive dimming reference circuit, wherein... The wire network detection circuit is connected to the input terminal of the power output circuit. It is used to perform a first sampling process on the wire network voltage value, output the sampled voltage value, and determine whether the wire network voltage is shunted by the thyristor based on the wire network voltage value, and output the thyristor control signal value. The LED lamp voltage detection circuit is connected to the input terminal of the power output circuit and the negative terminal of the entire LED segment, respectively, and is used to perform a second sampling process on the voltage difference of the entire LED segment and output the voltage threshold of the entire segment. The adaptive dimming reference circuit is connected to the LED lamp pressure detection circuit and the wire mesh detection circuit, respectively, and is used to linearly compare the sampled voltage value output by the wire mesh detection circuit and the whole voltage threshold output by the LED lamp pressure detection circuit, and output the dimming voltage value.

4. The dimming circuit for a multi-segment light-emitting diode as described in claim 3, characterized in that, The adaptive dimming reference circuit includes: a linear comparator, a first power switch, a first resistor, a second resistor, and multiple voltage divider resistors, wherein... The positive input terminal of the linear comparator is connected to the first output terminal of the wire mesh detection circuit, and the negative input terminal of the linear comparator is connected to the output terminal of the LED lamp voltage detection circuit, which is used to perform a linear comparison between the sampled voltage value and the entire voltage threshold and output a dimming current; The positive output terminal of the linear comparator is connected to the drain of the first power switch via the first resistor, the negative output terminal of the linear comparator is connected to the gate of the first power switch, and the source of the first power switch is grounded. The input terminal of the first resistor is connected to the clamping voltage, and the output terminal of the first resistor is grounded after passing through a link composed of the second resistor and multiple voltage divider resistors connected in series. The output terminals of the multiple voltage divider resistors are respectively connected to the LED constant current driving circuit, and the multiple dimming voltage values ​​output from the output terminals of the multiple voltage divider resistors are respectively input to the LED constant current driving circuit.

5. The dimming circuit for a multi-segment light-emitting diode as described in claim 4, characterized in that, The number of the plurality of voltage divider resistors is the same as the number of the plurality of sub-segments of the entire LED segment, and the plurality of voltage divider resistors correspond one-to-one with the sub-segment LEDs.

6. The dimming circuit for a multi-segment light-emitting diode as described in claim 4, characterized in that, The LED constant current driving circuit includes: a second power switch, a thyristor discharge circuit, and a constant current driving sub-circuit, wherein... The input terminal of the thyristor discharge circuit is connected to the second output terminal of the wire mesh detection circuit, and the output terminal of the thyristor discharge circuit is connected to the input terminal of the constant current resistor. It is used to judge the value of the thyristor control signal and determine whether to turn the thyristor discharge circuit on or off. The input terminal of the constant current driving sub-circuit is connected to the output terminals of the multiple voltage divider resistors in the adaptive dimming reference circuit and the negative terminal of each sub-segment LED in the entire LED segment. The output terminal of the constant current driving sub-circuit is connected to the input terminal of the constant current resistor to provide a constant current for each sub-segment LED. The output terminal of the constant current resistor is grounded. The gate of the second power switch is connected to the output terminal of the LED constant current judgment circuit, the drain of the second power switch is connected to the thyristor discharge circuit and the constant current drive sub-circuit respectively, and the source of the second power switch is grounded.

7. The dimming circuit for a multi-segment light-emitting diode as described in claim 6, characterized in that, The thyristor discharge circuit includes: a discharge resistor, a discharge amplifier, and a discharge power switch, wherein... The positive input terminal of the bleeder amplifier is connected to the second output terminal of the wire detection circuit, the negative input terminal of the bleeder amplifier is connected to the input terminal of the bleeder resistor, and the output terminal of the bleeder amplifier is connected to the gate of the bleeder power switch and the drain of the second power switch, respectively. The drain of the bleeder power switch is connected to the input terminal of the power output circuit, and the source of the bleeder power switch is connected to the input terminal of the bleeder resistor. The output terminal of the bleeder resistor is connected to the input terminal of the constant current resistor.

8. The dimming circuit for a multi-segment light-emitting diode as described in claim 6, characterized in that, The constant current drive sub-circuit includes: multiple dimming power switches and multiple dimming amplifiers, wherein... The positive input terminals of the plurality of dimming amplifiers are respectively connected to the output terminals of the corresponding voltage divider resistors in the adaptive dimming reference circuit, the negative input terminals of the plurality of dimming amplifiers are respectively connected to the input terminals of the constant current resistors, and the output terminals of the plurality of dimming amplifiers are respectively connected to the gate of the corresponding dimming power switch and the drain of the second power switch. The drains of the plurality of dimming power switches are respectively connected to the negative terminals of the corresponding sub-segments of LEDs, and the sources of the plurality of dimming power switches are respectively connected to the input terminals of the constant current resistors.

9. The dimming circuit for a multi-segment light-emitting diode as described in claim 1, characterized in that, The power output circuit includes: an AC power supply, a thyristor, and a rectifier bridge, wherein the thyristor is connected in series between the AC power supply and the rectifier bridge.

10. The dimming circuit for a multi-segment light-emitting diode as described in claim 9, characterized in that, The rectifier bridge includes a first diode, a second diode, a third diode, and a fourth diode, wherein, The rectifier bridge is composed of a first link consisting of the first diode and the second diode connected in series, and a second link consisting of the third diode and the fourth diode connected in series, connected in parallel. The positive terminal of the AC power supply is connected to the input terminal of the thyristor, and the negative terminal of the AC power supply is connected to the cathode terminal of the third diode in the rectifier bridge; the output terminal of the thyristor is connected to the anode terminal of the second diode in the rectifier bridge. The anode of the first diode and the anode of the third diode in the rectifier bridge are connected to the output terminal of the LED constant current drive circuit. The cathode of the second diode and the cathode of the fourth diode in the rectifier bridge are connected to the positive terminal of the entire LED segment.

11. A dimming method for a multi-segment light-emitting diode, characterized in that, The method, applied to a dimming circuit for a multi-segment light-emitting diode as described in any one of claims 1-10, comprises: Obtain the line voltage value output by the power supply output circuit and the total voltage difference of the entire LED segment; The control signal value of the thyristor is obtained based on the grid voltage value through the LED dimming circuit. When the thyristor control signal value is a first control signal value indicating that the grid voltage is tangent by the thyristor, the thyristor discharge circuit in the LED constant current drive circuit is turned on; and, The LED dimming circuit obtains a dimming voltage value based on the grid voltage value and the voltage difference of the entire LED segment, so that the current flowing through each sub-segment of the LED segment is adjusted according to the dimming voltage value by the LED constant current driving circuit.

12. The dimming method for multi-segment light-emitting diodes as described in claim 11, characterized in that, The LED dimming circuit includes a wire mesh detection circuit, an LED lamp pressure detection circuit, and an adaptive dimming reference circuit. The process of obtaining the dimming voltage value through the LED dimming circuit based on the grid voltage value and the total voltage difference includes: The wire network voltage value is first sampled by the wire network detection circuit to obtain the sampled voltage value; The LED lamp voltage detection circuit performs a second sampling process on the voltage difference of the entire LED segment to obtain the entire voltage threshold. The adaptive dimming reference circuit performs a linear comparison between the sampled voltage value and the entire voltage threshold. If the sampled voltage value is less than the entire voltage threshold, then the output dimming voltage value is the first dimming voltage value; If the sampled voltage value is greater than or equal to the entire voltage threshold, then the output dimming voltage value is the second dimming voltage value.

13. The dimming method for multi-segment light-emitting diodes as described in claim 12, characterized in that, When the thyristor control signal value is the first control signal value and the sampled voltage value is less than the overall voltage threshold, the step of adjusting the current flowing through each sub-segment of the LED in the entire LED segment according to the dimming voltage value via the LED constant current drive circuit includes: The negative output terminal of the linear comparator is connected to the gate of the first power switch. The positive output terminal of the linear comparator in the adaptive dimming reference circuit outputs a dimming current, and the dimming voltage value is the first dimming voltage value, so that the current flowing through the entire LED segment changes.

14. The dimming method for multi-segment light-emitting diodes as described in claim 12, characterized in that, When the thyristor control signal value is the first control signal value, and the sampled voltage value is greater than or equal to the overall voltage threshold, the step of adjusting the current flowing through each sub-segment of the LED in the entire LED segment according to the dimming voltage value via the LED constant current drive circuit includes: When the negative output terminal of the linear comparator is disconnected from the gate of the first power switch, and the positive output terminal of the linear comparator in the adaptive dimming reference circuit has no dimming current output, the dimming voltage value is the second dimming voltage value, so that the current flowing through the entire LED segment is a constant current.

15. The dimming method for multi-segment light-emitting diodes as described in claim 12, characterized in that, The method further includes: When the control signal value of the thyristor is the second control signal value indicating that the grid voltage is not tangential to the thyristor, the thyristor discharge circuit in the LED constant current drive circuit is turned off; and the negative output terminal of the linear comparator is disconnected from the gate of the first power switch, and there is no dimming current output at the positive output terminal of the linear comparator in the adaptive dimming reference circuit, then the current flowing through the entire LED segment is a constant current.

16. The dimming method for multi-segment light-emitting diodes as described in claim 11, characterized in that, The method further includes: Obtain the judgment result value output by the LED constant current judgment circuit from the power output circuit, wherein the judgment result value is used to characterize whether the voltage flowing through the entire LED segment is less than the total lamp segment voltage value; When the judgment result output by the LED constant current judgment circuit is the target result value, the entire LED segment and the thyristor discharge circuit are simultaneously turned off.

17. A lighting device, characterized in that, The lighting device includes a dimming circuit for a multi-segment light-emitting diode as described in any one of claims 1 to 10, wherein the dimming circuit for the multi-segment light-emitting diode performs a dimming method for a multi-segment light-emitting diode as described in any one of claims 11 to 16.

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