Lighting circuit and color temperature control method thereof

Abstract

The present invention discloses a lighting circuit and a color temperature control method thereof. The lighting circuit includes: an LED lamp bead, a first resistor, a second resistor, a first switch tube, a second switch tube, a controller, and a power supply; the resistance of the first resistor is greater than the resistance of the second resistor; the LED lamp bead, the first resistor, and the first switch tube are connected in series to both ends of the power supply; the LED lamp bead, the second resistor, and the second switch tube are connected in series to both ends of the power supply; the controller is used to output a pulse signal with a first duty cycle to the first switch tube and a pulse signal with a second duty cycle to the second switch tube in a time-sharing manner. The present invention outputs a pulse signal with a larger duty cycle to the first switch tube connected in series with the larger resistor, and outputs a pulse signal with a smaller duty cycle to the second switch tube connected in series with the smaller resistor, so that different color temperatures can be controlled using a single LED lamp bead, thereby improving control efficiency and reducing control costs.

Description

Technical Field

[0001] The present invention relates to the field of lighting technology, and in particular to a lighting circuit and a color temperature control method thereof. Background Art

[0002] In existing lighting technologies, in order to make the color temperature of LED (Light Emitting Diode) white light adjustable, different lamp beads are generally selected, the number of warm light lamp beads is increased, or the current driving the warm light lamp beads is increased to increase the proportion of warm light brightness, thereby making the color temperature warmer. Similarly, the number of cold light lamp beads is increased, or the current driving the cold light lamp beads is increased to increase the proportion of cold light brightness, thereby making the color temperature cooler. It is also possible to use three-primary color RGB LEDs, and change the color temperature by adjusting the brightness ratio of the lamp beads of each primary color. However, in order to ensure a certain brightness, multiple lamp beads or RGB high-brightness lamp beads are usually required, which is relatively expensive. In addition, since there is a color temperature deviation between each lamp bead, it is necessary to control the color temperature of each lamp bead. In order to make the overall color temperature relatively consistent, there is a great deal of controllability. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the above-mentioned defects in the prior art and provide a lighting circuit and a color temperature control method thereof.

[0004] The present invention solves the above technical problems through the following technical solutions:

[0005] A first aspect of the present invention provides a lighting circuit, comprising: an LED lamp bead, a first resistor, a second resistor, a first switching tube, a second switching tube, a controller, and a power supply; wherein the resistance of the first resistor is greater than the resistance of the second resistor;

[0006] The LED lamp bead, the first resistor and the first switch tube are connected in series and connected to both ends of the power supply;

[0007] The LED lamp bead, the second resistor and the second switch tube are connected in series and connected to both ends of the power supply;

[0008] The controller is used to output a pulse signal with a first duty cycle to the first switching tube in a time-sharing manner, and to output a pulse signal with a second duty cycle to the second switching tube, wherein the first duty cycle is greater than the second duty cycle.

[0009] Optionally, the anode of the LED lamp bead is electrically connected to the power supply terminal of the power supply, and the cathode of the LED lamp bead is electrically connected to one end of the first resistor and one end of the second resistor respectively;

[0010] The other end of the first resistor is electrically connected to the first end of the first switch tube, the other end of the second resistor is electrically connected to the first end of the second switch tube, and the second end of the first switch tube and the second end of the second switch tube are both electrically connected to the ground end of the power supply;

[0011] The controller is electrically connected to the control end of the first switch tube and the control end of the second switch tube respectively.

[0012] Optionally, the cathode of the LED lamp bead is electrically connected to the ground terminal of the power supply, and the anode of the LED lamp bead is electrically connected to one end of the first resistor and one end of the second resistor respectively;

[0013] The other end of the first resistor is electrically connected to the second end of the first switch tube, the other end of the second resistor is electrically connected to the second end of the second switch tube, and the first end of the first switch tube and the first end of the second switch tube are both electrically connected to the power supply terminal of the power supply;

[0014] The controller is electrically connected to the control end of the first switch tube and the control end of the second switch tube respectively.

[0015] Optionally, the lighting circuit further includes a third resistor and a third switch tube, wherein the resistance of the third resistor is smaller than the resistance of the first resistor and larger than the resistance of the second resistor;

[0016] The LED lamp bead, the second resistor and the second switch tube are connected in series and connected to both ends of the power supply;

[0017] The controller is further configured to output a pulse signal with a third duty cycle to the third switch tube in a time-sharing manner, wherein the third duty cycle is smaller than the first duty cycle and larger than the second duty cycle.

[0018] Optionally, the LED lamp bead is electrically connected to the first resistor and the second resistor respectively through a current limiting resistor.

[0019] Optionally, there are multiple LED lamp beads, each LED lamp bead has the same color temperature, and all LED lamp beads are connected in parallel.

[0020] Optionally, each LED lamp bead is electrically connected to the first resistor and the second resistor respectively through a current limiting resistor, and the resistance values ​​of all current limiting resistors are the same.

[0021] Optionally, the average power of the LED lamp beads remains unchanged.

[0022] Optionally, the first duty cycle is 100%.

[0023] Optionally, the lighting circuit is the lighting circuit described in the first aspect, and the color temperature control method includes the following steps:

[0024] In response to triggering the first mode, outputting a pulse signal with a first duty cycle to the first switch tube;

[0025] In response to triggering the second mode, outputting a pulse signal with a second duty cycle to the second switch tube;

[0026] The first duty cycle is greater than the second duty cycle.

[0027] The positive progressive effect of the present invention is that by outputting a pulse signal with a larger duty cycle, i.e., a first duty cycle, to a first switching tube connected in series with a larger resistor, i.e., a first resistor, and by outputting a pulse signal with a smaller duty cycle, i.e., a second duty cycle, to a second switching tube connected in series with a smaller resistor, i.e., a second resistor, different color temperature control can be achieved using one LED lamp bead. Compared with the prior art, there is no need to set LED lamp beads with different color temperatures, thereby improving the efficiency of color temperature control and reducing the cost of color temperature control. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a circuit diagram of a lighting circuit provided in Example 1 of the present invention.

[0029] Figure 2 This is a circuit diagram of another lighting circuit provided in Example 1 of the present invention.

[0030] Figure 3 This is a circuit diagram of another lighting circuit provided in Example 1 of the present invention.

[0031] Figure 4 This is a circuit diagram of another lighting circuit provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0032] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples.

[0033] Example 1

[0034] This embodiment provides a lighting circuit, such as Figure 1 As shown, it includes: LED lamp bead D1, first resistor R1, second resistor R2, first switch tube Q1, second switch tube Q2, controller and power supply. Among them, the resistance of the first resistor R1 is greater than the resistance of the second resistor R2.

[0035] The LED lamp bead D1, the first resistor R1, and the first switch tube Q1 are connected in series and then connected to the two ends of the power supply. The LED lamp bead D2, the second resistor R2, and the second switch tube Q2 are connected in series and then connected to the two ends of the power supply. The power supply is a DC power supply.

[0036] The controller is configured to time-share output a pulse signal PWM1 with a first duty cycle to the first switching transistor Q1, and a pulse signal PWM2 with a second duty cycle to the second switching transistor Q2. In other words, while the controller outputs a pulse signal to the first switching transistor, it does not output a pulse signal to the second switching transistor. Similarly, while the controller outputs a pulse signal to the second switching transistor, it does not output a pulse signal to the first switching transistor.

[0037] The first duty cycle is greater than the second duty cycle. In a specific example, in order to make the LED lamp beads meet the desired color temperature effect, the first duty cycle can be 100.

[0038] exist Figure 1 In the example shown, the first switching transistor Q1 and the second switching transistor Q2 are both triodes. The first switching transistor Q1 has a first terminal serving as a collector, a second terminal serving as an emitter, and a control terminal serving as a base. The second switching transistor Q2 has a first terminal serving as a collector, a second terminal serving as an emitter, and a control terminal serving as a base. It should be noted that in other examples, the first switching transistor and the second switching transistor may also be switch chips, etc.

[0039] In a specific implementation, the color temperature of the LED lamp bead can be relatively small. By outputting a pulse signal with a first duty cycle to the first resistor, the current is increased, thereby achieving a warm light effect, and by outputting a pulse signal with a second duty cycle to the second resistor, the current is reduced, thereby achieving a cold light effect.

[0040] The color temperature of the LED lamp beads can also be higher. By outputting a pulse signal with a first duty cycle to the first resistor to increase the current, a cooler light effect is achieved. By outputting a pulse signal with a second duty cycle to the second resistor to reduce the current, a warmer light effect is achieved. In the example of using blue light to excite yellow phosphor to generate white light, the color temperature of the LED lamp beads is relatively high. When the current increases, the brightness increases, the energy of the blue light increases, and the overall phosphor does not change. Therefore, the color temperature of the generated white light will be bluish, that is, cooler.

[0041] In the lighting circuit provided in this embodiment, a pulse signal with a larger duty cycle, i.e., a first duty cycle, is output to a first switching tube connected in series with a larger resistor, i.e., a first resistor, and a pulse signal with a smaller duty cycle, i.e., a second duty cycle, is output to a second switching tube connected in series with a smaller resistor, i.e., a second resistor, so that control of different color temperatures can be achieved using one LED lamp bead. Compared with the prior art, there is no need to set LED lamp beads with different color temperatures, thereby improving the efficiency of color temperature control and reducing the cost of color temperature control.

[0042] In a specific example, Figure 2 As shown, the anode of LED lamp bead D1 is electrically connected to the power supply terminal VDD of the power supply, and the cathode of LED lamp bead D1 is electrically connected to one end of the first resistor R1 and one end of the second resistor R2. The other end of the first resistor R1 is electrically connected to the collector of the first switching transistor Q1, and the other end of the second resistor R2 is electrically connected to the collector of the second switching transistor Q2. The emitters of the first switching transistor Q1 and the second switching transistor Q2 are both electrically connected to the ground terminal GND of the power supply. The controller is electrically connected to the base of the first switching transistor Q1 and the base of the second switching transistor Q2.

[0043] In this example, when the first switch Q1 is turned on, the current flows through the LED lamp bead D1, the first resistor R1, and the first switch Q1 in sequence. When the second switch Q1 is turned on, the current flows through the LED lamp bead D1, the first resistor R2, and the first switch Q2 in sequence.

[0044] In another specific example, Figure 3 As shown, the cathode of LED lamp bead D1 is electrically connected to the ground terminal GND of the power supply, and the anode of LED lamp bead D1 is electrically connected to one end of the first resistor R1 and one end of the second resistor R2. The other end of the first resistor R1 is electrically connected to the emitter of the first switching transistor Q1, and the other end of the second resistor R2 is electrically connected to the emitter of the second switching transistor Q2. The collectors of the first switching transistor Q1 and the collectors of the second switching transistor Q2 are both electrically connected to the power supply terminal VDD of the power supply. The controller is electrically connected to the base of the first switching transistor Q1 and the base of the second switching transistor Q2.

[0045] In this example, when the first switch Q1 is turned on, the current flows through the first switch Q1, the first resistor R1, and the LED lamp bead D1 in sequence. When the second switch Q1 is turned on, the current flows through the second switch Q2, the second resistor R2, and the LED lamp bead D1 in sequence.

[0046] In an optional embodiment, the LED lamp bead is electrically connected to the first resistor and the second resistor respectively through a current-limiting resistor. In this embodiment, the current-limiting resistor is used to limit the magnitude of the current in the branch to prevent excessive current from causing damage to the LED lamp bead, the first switching tube, or the second switching tube.

[0047] In an optional embodiment, if the power of the LED lamp beads is too low to meet actual needs, multiple LED lamp beads with the same color temperature can be selected and connected in parallel. Specifically, the number of the LED lamp beads is multiple, and each LED lamp bead has the same color temperature, and all LED lamp beads are connected in parallel.

[0048] In an optional embodiment, each LED lamp bead is electrically connected to the first resistor and the second resistor via a current-limiting resistor, and all current-limiting resistors have the same resistance value. In this embodiment, when multiple LED lamp beads are used for color temperature control, if the voltage drop of each LED lamp bead is not completely consistent, by providing current-limiting resistors with the same resistance value, LED lamp beads with smaller voltage drops can be protected from damage caused by excessive current.

[0049] In an optional embodiment, the lighting circuit further includes a third resistor and a third switching transistor, wherein the resistance of the third resistor is smaller than the resistance of the first resistor and larger than the resistance of the second resistor. The LED lamp bead, the second resistor, and the second switching transistor are connected in series to both ends of the power supply.

[0050] The controller is further configured to time-share output a pulse signal having a third duty cycle to the third switching transistor. That is, while the controller outputs a pulse signal to the first switching transistor, it does not output pulse signals to the second and third switching transistors. Similarly, while the controller outputs a pulse signal to the second switching transistor, it does not output pulse signals to the first and third switching transistors; and while the controller outputs a pulse signal to the third switching transistor, it does not output pulse signals to the first and second switching transistors.

[0051] The third duty cycle is smaller than the first duty cycle and larger than the second duty cycle.

[0052] This embodiment is provided with a first switching tube, a second switching tube, a third switching tube, a first resistor, a second resistor, and a third resistor between the first resistor and the second resistor. The controller outputs pulse signals with different duty cycles to different switching tubes in a time-sharing manner, which can adjust more color temperature effects, thereby enriching the user's usage needs and improving the user's lighting experience.

[0053] like Figure 4The lighting circuit shown includes m LED lamp beads D1 to Dm with the same color temperature, m current-limiting resistors R11 to R1m, a first resistor R1 to an nth resistor Rn, a first switch Q1 to an nth switch Qn, and a controller. The controller is used to output a pulse signal with an nth duty cycle to the nth switch Qn. Wherein, m and n are both integers greater than or equal to 3. In this example, the resistance values ​​of the first resistor R1 to the nth resistor Rn decrease in sequence, and the duty cycle of the pulse signal output by the controller to the first switch Q1 to the nth switch Qn also decreases in sequence. In this example, by setting the first resistor R1 to the nth resistor Rn and the first switch Q1 to the nth switch Qn, more color temperature effects can be further adjusted, which greatly enriches the user's usage needs and enhances the user's lighting experience.

[0054] In an optional embodiment, the average power of the LED lamp beads remains unchanged. In a specific implementation, the controller outputs a pulse signal with a first duty cycle to a first switching tube connected in series with a first resistor, causing the LED lamp beads to achieve a first color temperature effect. A second duty cycle is calculated based on the power of the LED lamp beads when achieving the first color temperature effect and the second resistor. The controller then outputs a pulse signal with a second duty cycle to a second switching tube, causing the LED lamp beads to achieve a second color temperature effect. In this embodiment, color temperature adjustment is achieved while maintaining the average power of the LED lamp beads.

[0055] Example 2

[0056] Based on the lighting circuit provided in Example 1, this embodiment provides a color temperature control method for a lighting circuit, specifically comprising the following steps S101 and S102:

[0057] Step S101: In response to triggering a first mode, outputting a pulse signal with a first duty cycle to a first switch tube.

[0058] Step S102: In response to triggering the second mode, output a pulse signal with a second duty cycle to the second switch tube, wherein the first duty cycle is greater than the second duty cycle.

[0059] Among them, the first mode and the second mode are two independent modes, which can be actively triggered by the user or passively triggered according to instructions. The first mode and the second mode correspond to different color temperature effects respectively. In a specific example, the color temperature of the LED lamp bead is relatively low, and the first mode can be a warm light mode corresponding to a warm light effect; the second mode can be a cold light mode corresponding to a cold light effect. In another specific example, the color temperature of the LED lamp bead is relatively high, and the first mode can be a cold light mode corresponding to a cold light effect; the second mode can be a warm light mode corresponding to a warm light effect.

[0060] In this embodiment, in response to different modes, by outputting pulse signals with different duty cycles to different switch tubes connected in series with the LED lamp beads, different color temperature effects can be controlled, thereby improving the efficiency of color temperature control and reducing the cost of color temperature control.

[0061] In an embodiment in which the lighting circuit further includes a third resistor and a third switch tube, the color temperature control method further includes the following step S103:

[0062] Step S103: In response to triggering the third mode, output a pulse signal with a third duty cycle to the third switch tube, wherein the third duty cycle is smaller than the first duty cycle and larger than the second duty cycle.

[0063] In this embodiment, the first, second, and third modes are independent modes that can be triggered actively by the user or passively by a command. Each of the first, second, and third modes corresponds to a different color temperature effect, enriching user needs and enhancing the user's lighting experience.

[0064] Although specific embodiments of the present invention have been described above, those skilled in the art will appreciate that these are merely illustrative and that the scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, and such changes and modifications are intended to fall within the scope of the present invention.

Claims

1. A lighting circuit, characterized in that: include: LED lamp beads, a first resistor, a second resistor, a first switch tube, a second switch tube, a controller and a power supply; wherein the resistance of the first resistor is greater than the resistance of the second resistor; The LED lamp bead, the first resistor and the first switch tube are connected in series and connected to both ends of the power supply; The LED lamp bead, the second resistor and the second switch tube are connected in series and connected to both ends of the power supply; The LED lamp bead is electrically connected to the first resistor and the second resistor respectively through a current limiting resistor, and the average power of the LED lamp bead remains unchanged; The controller is used to output a pulse signal with a first duty cycle to the first switching tube in a time-sharing manner, and to output a pulse signal with a second duty cycle to the second switching tube, wherein the first duty cycle is greater than the second duty cycle.

2. The lighting circuit according to claim 1, wherein: The anode of the LED lamp bead is electrically connected to the power supply end of the power supply, and the cathode of the LED lamp bead is electrically connected to one end of the first resistor and one end of the second resistor respectively; The other end of the first resistor is electrically connected to the first end of the first switch tube, the other end of the second resistor is electrically connected to the first end of the second switch tube, and the second end of the first switch tube and the second end of the second switch tube are both electrically connected to the ground end of the power supply; The controller is electrically connected to the control end of the first switch tube and the control end of the second switch tube respectively.

3. The lighting circuit according to claim 1, wherein: The cathode of the LED lamp bead is electrically connected to the ground terminal of the power supply, and the anode of the LED lamp bead is electrically connected to one end of the first resistor and one end of the second resistor respectively; The other end of the first resistor is electrically connected to the second end of the first switch tube, the other end of the second resistor is electrically connected to the second end of the second switch tube, and the first end of the first switch tube and the first end of the second switch tube are both electrically connected to the power supply terminal of the power supply; The controller is electrically connected to the control end of the first switch tube and the control end of the second switch tube respectively.

4. The lighting circuit according to claim 1, wherein The lighting circuit further includes a third resistor and a third switch tube, wherein the resistance of the third resistor is smaller than the resistance of the first resistor and larger than the resistance of the second resistor; The LED lamp bead, the second resistor and the second switch tube are connected in series and connected to both ends of the power supply; The controller is further configured to output a pulse signal with a third duty cycle to the third switch tube in a time-sharing manner, wherein the third duty cycle is smaller than the first duty cycle and larger than the second duty cycle.

5. The lighting circuit according to claim 1, wherein: There are multiple LED lamp beads, each of which has the same color temperature, and all of the LED lamp beads are connected in parallel.

6. The lighting circuit according to claim 5, wherein: Each LED lamp bead is electrically connected to the first resistor and the second resistor respectively through a current limiting resistor, and the resistance values ​​of all current limiting resistors are the same.

7. The lighting circuit according to any one of claims 1 to 6, characterized in that: The first duty cycle is 100%.

8. A method for controlling the color temperature of a lighting circuit, characterized in that: The lighting circuit is the lighting circuit according to any one of claims 1 to 7, and the color temperature control method comprises the following steps: In response to triggering the first mode, outputting a pulse signal with a first duty cycle to the first switch tube; In response to triggering the second mode, outputting a pulse signal with a second duty cycle to the second switch tube; The first duty cycle is greater than the second duty cycle.

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