LED control circuit and LED lamp with both color temperature and brightness adjustment

Abstract

The present invention relates to an LED control circuit and an LED lamp capable of both color temperature and brightness adjustment. The LED control circuit is used to control an LED lamp panel, which includes a first light string and a second light string connected in parallel with different color temperatures. The LED control circuit includes a DC power supply and a bridge switch circuit. The bridge switch circuit includes four switching tubes, which are connected in series in pairs to form a first series bridge arm and a second series bridge arm, respectively. The first series bridge arm and the second series bridge arm are connected in parallel. A DC power supply connects the two ends of the two series bridge arms. The midpoints of the two series bridge arms lead to a first connecting line and a second connecting line for connecting to the LED lamp panel, respectively. The two diagonally located bridge arms are paired in pairs to form a first control branch and a second control branch. The control circuit also includes a color temperature adjustment drive circuit and a brightness adjustment drive circuit, respectively connected to the two control branches. Compared with the prior art, the present invention has a simple circuit structure and low cost.

Description

Technical Field

[0001] The present invention relates to the technical field of LED lamps and control circuits thereof, and in particular to an LED control circuit and an LED lamp capable of adjusting color temperature and brightness. Background Art

[0002] Currently, the voltage conversion circuit for adjusting the color temperature of LED lamps on the market is complex. The connection between the controller and the light board requires multiple wires, which is costly and difficult to layout the PCB. At the same time, if the brightness and color temperature adjustment functions need to be realized at the same time, the control circuit will be more complicated, requiring more leads to connect with the LED light board, which is costly. Summary of the Invention

[0003] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide an LED control circuit and an LED lamp with both color temperature and brightness adjustment.

[0004] The purpose of the present invention can be achieved by the following technical solutions:

[0005] An LED control circuit capable of both color temperature and brightness adjustment, used for controlling an LED light panel, the LED light panel including a first light string and a second light string connected in parallel with different color temperatures, the LED control circuit including a DC power supply and a bridge switching circuit, the bridge switching circuit including four switching tubes, the four switching tubes being connected in series in pairs to form a first series bridge arm and a second series bridge arm, respectively, the first and second series bridge arms being connected in parallel, the DC power supply connecting both ends of the first and second series bridge arms, a first connecting line extending from the midpoint of the first series bridge arm, and a second connecting line extending from the midpoint of the second series bridge arm, the first and second connecting lines being used to connect to the LED light panel, and two diagonally located bridge arms in the bridge switching circuit being paired to form a first control branch and a second control branch;

[0006] The control circuit further comprises a color temperature adjustment driving circuit and a brightness adjustment driving circuit, wherein the color temperature adjustment driving circuit and the brightness adjustment driving circuit are connected to the first control branch and the second control branch respectively.

[0007] Preferably, the two switching tubes in the first control branch and the second control branch are respectively configured as a color temperature adjustment switching tube and a brightness adjustment switching tube, the color temperature adjustment driving circuit is respectively connected to the color temperature adjustment switching tubes in the two control branches, and the brightness adjustment driving circuit is respectively connected to the brightness adjustment switching tubes in the two control branches.

[0008] Preferably, the color temperature adjustment driving circuit is configured as a driving circuit that controls the color temperature adjustment switching tubes in the two control branches to be turned on alternately.

[0009] Preferably, the brightness adjustment driving circuit is configured as a driving circuit that controls the brightness adjustment switching tubes in the two control branches to be turned on at a certain duty cycle when the color temperature adjustment switching tubes in the corresponding control branches are turned on.

[0010] Preferably, the color temperature adjustment driving circuit includes a first color temperature adjustment signal generator, a second color temperature adjustment signal generator, a first AND gate logic device, a first NOT gate logic device, a first color temperature adjustment switch tube driving circuit and a second color temperature adjustment switch tube driving circuit. The first color temperature adjustment signal generator and the second color temperature adjustment signal generator are used to output complementary high and low level signals. The first color temperature adjustment signal generator and the second color temperature adjustment signal generator are connected to the first AND gate logic device, the output end of the first AND gate logic device is connected to the first color temperature adjustment switch tube driving circuit, the output end of the first AND gate logic device is also connected to the second color temperature adjustment switch tube driving circuit through the first NOT gate logic device, the first color temperature adjustment switch tube driving circuit is connected to the color temperature adjustment switch tube in the first control branch, and the second color temperature adjustment switch tube driving circuit is connected to the color temperature adjustment switch tube in the second control branch.

[0011] Preferably, the brightness adjustment drive circuit includes a first PWM signal generator, a second PWM signal generator, a first PWM modulation control circuit, a second PWM modulation control circuit, a second NOT gate logic device, a first brightness adjustment switch tube drive circuit, and a second brightness temperature adjustment switch tube drive circuit. The output end of the first AND gate logic device of the color temperature adjustment drive circuit is connected to the input end of the first PWM modulation control circuit, and the output end of the first AND gate logic device of the color temperature adjustment drive circuit is further connected to the input end of the second PWM modulation control circuit via the second NOT gate logic device. The first PWM signal generator and the second PWM signal generator are respectively connected to the input ends of the first PWM modulation control circuit and the second PWM modulation control circuit. The output ends of the first PWM modulation control circuit and the second PWM modulation control circuit are respectively connected to the first brightness adjustment switch tube drive circuit and the second brightness temperature adjustment switch tube drive circuit. The first brightness adjustment switch tube drive circuit is connected to the brightness adjustment switch tube in the first control branch, and the second brightness adjustment switch tube drive circuit is connected to the brightness adjustment switch tube in the second control branch.

[0012] Preferably, the first PWM modulation control circuit and the second PWM modulation control circuit respectively include a second AND gate logic device and a third AND gate logic device that perform AND operations.

[0013] Preferably, a dead time control circuit is further provided between the output end of the first AND gate logic device and the subsequent circuit.

[0014] Preferably, the switch tube is a MOS tube.

[0015] An LED lamp includes an LED lamp board, wherein the LED lamp board includes a first lamp string and a second lamp string connected in parallel and having different color temperatures. The LED lamp also includes the above-mentioned LED control circuit, wherein the first connecting line and the second connecting line of the LED control circuit are connected to the LED lamp board.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] (1) The LED control circuit of the present invention only requires two connecting wires to connect to the LED light board, and can simultaneously adjust the color temperature and brightness, with a simple structure;

[0018] (2) The color temperature adjustment driving circuit of the present invention controls the color temperature adjustment switch tubes in the two control branches to be turned on alternately. The principle of adjusting the color temperature is: the color temperature is infinitely adjusted by controlling the conduction time of the two groups of light strings with different color temperatures within one cycle; the brightness adjustment driving circuit controls the brightness adjustment switch tubes in the two control branches to be turned on according to a certain duty cycle when the color temperature adjustment switch tubes in the corresponding control branches are turned on. The principle of adjusting the brightness is: brightness adjustment is achieved by controlling the conduction duty cycle of the two groups of light strings; this adjustment method can achieve fast and accurate adjustment;

[0019] (3) The color temperature adjustment driving circuit and the brightness adjustment driving circuit of the present invention have simple structures and low costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the connection circuit between an LED control circuit and an LED light board with both color temperature and brightness adjustment capabilities of the present invention. DETAILED DESCRIPTION

[0021] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. Note that the following embodiments are merely illustrative in nature and the present invention is not intended to limit its applicable objects or uses, and the present invention is not limited to the following embodiments.

[0022] Example 1

[0023] like Figure 1 As shown, this embodiment provides an LED control circuit with both color temperature and brightness adjustment, which is used to control an LED light board. The LED light board includes a first light string and a second light string with different color temperatures connected in parallel. In this embodiment, the first light string includes white light lamps D1 and D2 connected in series, and the second light string includes yellow light lamps D3 and D4 connected in series.

[0024] The LED control circuit includes a DC power supply and a bridge switch circuit. The bridge switch circuit includes four switch tubes. The four switch tubes are connected in series in pairs to form a first series bridge arm and a second series bridge arm respectively. The first series bridge arm and the second series bridge arm are connected in parallel. The DC power supply connects the two ends of the first series bridge arm and the second series bridge arm. A first connecting line is drawn out from the midpoint of the first series bridge arm, and a second connecting line is drawn out from the midpoint of the second series bridge arm. The first connecting line and the second connecting line are used to connect the LED light board. The two diagonally located bridge arms in the bridge switch circuit are paired in pairs to form a first control branch and a second control branch. The control circuit also includes a color temperature adjustment drive circuit and a brightness adjustment drive circuit. The color temperature adjustment drive circuit and the brightness adjustment drive circuit are connected to the first control branch and the second control branch respectively. In this embodiment, as Figure 1 As shown, VDC is a DC power supply, the switch tubes are all MOS tubes, the switch tubes Q1 and Q4 form a first control branch for controlling the first light string, and the switch tubes Q2 and Q3 form a second control branch for switching to the second light string.

[0025] The two switching transistors in the first and second control branches are configured as a color temperature adjustment switch and a brightness adjustment switch, respectively. The color temperature adjustment drive circuit is connected to the color temperature adjustment switch transistors in the two control branches, and the brightness adjustment drive circuit is connected to the brightness adjustment switch transistors in the two control branches. In this embodiment, switches Q1 and Q2 are configured as color temperature adjustment switches, and switches Q3 and Q4 are configured as brightness adjustment switches.

[0026] The color temperature adjustment drive circuit is configured to control the color temperature adjustment switches in the two control branches to be turned on alternately. The brightness adjustment drive circuit is configured to control the brightness adjustment switches in the two control branches to be turned on at a certain duty cycle when the color temperature adjustment switches in the corresponding control branches are turned on.

[0027] The color temperature adjustment driving circuit includes a first color temperature adjustment signal generator, a second color temperature adjustment signal generator, a first AND gate logic device, a first NOT gate logic device, a first color temperature adjustment switch tube driving circuit, and a second color temperature adjustment switch tube driving circuit. The first color temperature adjustment signal generator and the second color temperature adjustment signal generator are used to output complementary high and low level signals. The first color temperature adjustment signal generator and the second color temperature adjustment signal generator are connected to the first AND gate logic device. The output end of the first AND gate logic device is connected to the first color temperature adjustment switch tube driving circuit. The output end of the first AND gate logic device is also connected to the second color temperature adjustment switch tube driving circuit through the first NOT gate logic device. The first color temperature adjustment switch tube driving circuit is connected to the color temperature adjustment switch tube in the first control branch, and the second color temperature adjustment switch tube driving circuit is connected to the color temperature adjustment switch tube in the second control branch.

[0028] The brightness adjustment drive circuit includes a first PWM signal generator, a second PWM signal generator, a first PWM modulation control circuit, a second PWM modulation control circuit, a second NOT gate logic, a first brightness adjustment switch tube drive circuit, and a second brightness temperature adjustment switch tube drive circuit. The output of the first AND gate logic of the color temperature adjustment drive circuit is connected to the input of the first PWM modulation control circuit. The output of the first AND gate logic of the color temperature adjustment drive circuit is also connected to the input of the second PWM modulation control circuit via a second NOT gate logic. The first PWM signal generator and the second PWM signal generator are respectively connected to the inputs of the first PWM modulation control circuit and the second PWM modulation control circuit. The outputs of the first PWM modulation control circuit and the second PWM modulation control circuit are respectively connected to the first brightness adjustment switch tube drive circuit and the second brightness temperature adjustment switch tube drive circuit. The first brightness adjustment switch tube drive circuit is connected to the brightness adjustment switch tube in the first control branch, and the second brightness adjustment switch tube drive circuit is connected to the brightness adjustment switch tube in the second control branch. The first PWM modulation control circuit and the second PWM modulation control circuit respectively include a second AND gate logic and a third AND gate logic for performing an AND operation. A dead time control circuit is also provided between the output of the first AND gate logic and the subsequent circuit. Among them, the dead time control circuit is a standard control circuit, the first brightness adjustment switch tube driving circuit, the second brightness temperature adjustment switch tube driving circuit, the first brightness adjustment switch tube driving circuit and the second brightness adjustment switch tube driving circuit are all standard MOS tube driving circuits, Figure 1 The specific circuit diagram is not shown.

[0029] In this embodiment, the first color temperature adjustment signal generator and the second color temperature adjustment signal generator generate Figure 1 The 1IN and 2IN signals in the first PWM signal generator and the second PWM signal generator generate Figure 1 In the PWM1 and PWM2 signals, when 1IN is high, Q1 and Q4 are turned on, and D1 and D2 are lit. When 2IN is high, Q2 and Q3 are turned on, and D3 and D4 are lit. When 1IN and 2IN are low, both MOSFETs are turned off. 1IN and 2IN can be two complementary PWM input signals, which can achieve alternating lighting of D1, D2, and D3, D4, with different brightness times, thereby achieving the color temperature adjustment function. While achieving color temperature adjustment, it also adjusts brightness. There are two PWM control signal input ports PWM1 and PWM2. These two signals control the duty cycle of the PWM signal generated by the PWM GEN module. PWM1 controls the PWM duty cycle when Q4 is turned on, and PWM2 controls the PWM duty cycle when Q3 is turned on. Different duty cycles achieve different brightness when D1, D2, D3, and D4 are turned on.

[0030] Example 2

[0031] This embodiment provides an LED lamp, including an LED light board, the LED light board including a first light string and a second light string connected in parallel, each having different color temperatures. The LED lamp also includes the aforementioned LED control circuit, wherein a first connecting wire and a second connecting wire of the LED control circuit are connected to the LED light board. The LED control circuit is the same as that in Embodiment 1 and is not further described here.

[0032] The above embodiments are merely examples and do not limit the scope of the present invention. These embodiments can be implemented in various other ways, and various omissions, replacements, and changes can be made without departing from the technical concept of the present invention.

Claims

1. An LED control circuit capable of both color temperature and brightness adjustment, for controlling an LED light panel, wherein the LED light panel comprises a first light string and a second light string connected in parallel with different color temperatures, characterized in that: The LED control circuit includes a DC power supply and a bridge switch circuit. The bridge switch circuit includes four switching tubes. Two switching tubes are connected in series in a group to form a first series bridge arm and a second series bridge arm. The first series bridge arm and the second series bridge arm are connected in parallel. The DC power supply connects both ends of the first series bridge arm and the second series bridge arm. A first connecting line is led out from the midpoint of the first series bridge arm, and a second connecting line is led out from the midpoint of the second series bridge arm. The first connecting line and the second connecting line are used to connect to the LED light board. The two diagonally located bridge arms in the bridge switch circuit are paired to form a first control branch and a second control branch. The control circuit further includes a color temperature adjustment driving circuit and a brightness adjustment driving circuit, wherein the color temperature adjustment driving circuit and the brightness adjustment driving circuit are respectively connected to the first control branch and the second control branch; The two switching tubes in the first control branch and the second control branch are respectively configured as a color temperature adjustment switching tube and a brightness adjustment switching tube, the color temperature adjustment driving circuit is respectively connected to the color temperature adjustment switching tubes in the two control branches, and the brightness adjustment driving circuit is respectively connected to the brightness adjustment switching tubes in the two control branches; The color temperature adjustment drive circuit includes a first color temperature adjustment signal generator, a second color temperature adjustment signal generator, a first AND gate logic device, a first NOT gate logic device, a first color temperature adjustment switch tube drive circuit, and a second color temperature adjustment switch tube drive circuit. The first color temperature adjustment signal generator and the second color temperature adjustment signal generator are used to output complementary high and low level signals. The first color temperature adjustment signal generator and the second color temperature adjustment signal generator are connected to the first AND gate logic device. The output end of the first AND gate logic device is connected to the first color temperature adjustment switch tube drive circuit. The output end of the first AND gate logic device is also connected to the second color temperature adjustment switch tube drive circuit through the first NOT gate logic device. The first color temperature adjustment switch tube drive circuit is connected to the color temperature adjustment switch tube in the first control branch, and the second color temperature adjustment switch tube drive circuit is connected to the color temperature adjustment switch tube in the second control branch. The brightness adjustment drive circuit includes a first PWM signal generator, a second PWM signal generator, a first PWM modulation control circuit, a second PWM modulation control circuit, a second NOT gate logic device, a first brightness adjustment switch tube drive circuit, and a second brightness adjustment switch tube drive circuit. The output end of the first AND gate logic device of the color temperature adjustment drive circuit is connected to the input end of the first PWM modulation control circuit. The output end of the first AND gate logic device of the color temperature adjustment drive circuit is also connected to the input end of the second PWM modulation control circuit through the second NOT gate logic device. The first PWM signal generator and the second PWM signal generator are respectively connected to the input ends of the first PWM modulation control circuit and the second PWM modulation control circuit. The output ends of the first PWM modulation control circuit and the second PWM modulation control circuit are respectively connected to the first brightness adjustment switch tube drive circuit and the second brightness adjustment switch tube drive circuit. The first brightness adjustment switch tube drive circuit is connected to the brightness adjustment switch tube in the first control branch, and the second brightness adjustment switch tube drive circuit is connected to the brightness adjustment switch tube in the second control branch.

2. The LED control circuit with both color temperature and brightness adjustment according to claim 1, characterized in that: The color temperature adjustment driving circuit is configured as a driving circuit that controls the color temperature adjustment switching tubes in the two control branches to be turned on alternately.

3. The LED control circuit with both color temperature and brightness adjustment according to claim 2, characterized in that: The brightness adjustment driving circuit is configured as a driving circuit that controls the brightness adjustment switching tubes in the two control branches to be turned on according to a certain duty cycle when the color temperature adjustment switching tubes in the corresponding control branches are turned on.

4. The LED control circuit with both color temperature and brightness adjustment according to claim 1, characterized in that: The first PWM modulation control circuit includes a second AND gate logic device and a third AND gate logic device that perform an AND operation, and the second PWM modulation control circuit also includes a second AND gate logic device and a third AND gate logic device that perform an AND operation.

5. The LED control circuit with both color temperature and brightness adjustment according to claim 1, characterized in that: A dead time control circuit is further provided between the output end of the first AND gate logic device and the subsequent circuit.

6. The LED control circuit with both color temperature and brightness adjustment according to claim 1, characterized in that: The switch tube is a MOS tube.

7. An LED lamp, comprising an LED light board, wherein the LED light board comprises a first light string and a second light string connected in parallel and having different color temperatures, wherein: The LED lamp further comprises the LED control circuit according to any one of claims 1 to 6, wherein the first connecting line and the second connecting line of the LED control circuit are connected to the LED lamp board.

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