A color temperature control circuit and a driving circuit for a color-adjustable dimming LED lamp

Abstract

The present invention discloses a color temperature control circuit and a driving circuit for a color-modulating dimming LED lamp, comprising: a voltage conversion circuit for converting the lower voltage of the voltage outputted from the first detection terminal and the second detection terminal into a corresponding DC voltage; a first signal conversion circuit and a second signal conversion circuit for converting a connected PWM signal and a voltage signal outputted from the voltage conversion circuit into a corresponding DC voltage; a first voltage-controlled constant current circuit and a second voltage-controlled constant current circuit for controlling the maximum conduction current value between the output terminal and the negative electrode through the voltage signal outputted from the signal conversion circuit. The present invention provides a color temperature control circuit with a low ripple output current, so that both the low color temperature light-emitting circuit and the high color temperature light-emitting circuit emit light at a low frequency, thereby keeping the color-modulating dimming LED lamp in a low frequency flicker state.

Description

Technical Field

[0001] The present invention relates to the technical field of color-adjustable dimming LED lamps, and in particular to a color temperature control circuit and a driving circuit for a color-adjustable dimming LED lamp. Background Art

[0002] Dimmable and color-adjustable LED lamps with adjustable brightness and color temperature have been widely recognized by the market because of their advantages of energy saving and easier to meet people's needs for light color.

[0003] The driving circuit of a color-dimming LED lamp usually includes a constant current driving circuit, a dimming control circuit, a color temperature control circuit, a high color temperature light-emitting circuit and a low color temperature light-emitting circuit. The constant current driving circuit is connected to the mains and connected to the mains voltage. The dimming control circuit is connected to the constant current driving circuit, and controls the output current of the constant current driving circuit by a PWM signal that adjusts the brightness. The high color temperature light-emitting circuit and the low color temperature light-emitting circuit are connected to the constant current driving circuit, and emit light under the control of the current output by the constant current driving circuit. The total light intensity emitted by the high color temperature light-emitting circuit and the low color temperature light-emitting circuit is proportional to the current output by the constant current driving circuit. The constant current driving circuit can adjust the brightness of the dimming and color-adjusting LED lamp under the control of the brightness adjustment PWM information of the dimming control circuit.

[0004] The dimming control circuit is connected to the color temperature control circuit, and the color temperature control circuit has two output terminals, one of which is connected to the high color temperature light-emitting circuit, and the other is connected to the low color temperature light-emitting circuit. The dimming control circuit outputs a PWM signal for controlling the color temperature, and controls the two output terminals of the color temperature control circuit in a complementary on-off control mode, and controls the on-time ratio of the two output terminals, so that the average current flowing through the high color temperature light-emitting circuit and the average current flowing through the low color temperature light-emitting circuit are different, and different mixed light color temperatures of the LED lamp are generated. The complementary on-off control mode refers to a control mode in which when one port is turned on, the other port is turned off; or when one port is turned off, the other port is turned on.

[0005] The current output end of the constant current drive circuit of the prior art has a positive output end and a negative output end. Because the brightness of the LED lamp is proportional to the size of the drive current, the output end of the constant current drive circuit has an electrolytic capacitor, the positive electrode of the electrolytic capacitor is connected to its positive output end, and the negative electrode of the electrolytic capacitor is connected to its negative output end to reduce the ripple of the output current, thereby reducing the luminous flicker of the light-emitting circuit connected to the output end. At the same time, when the load changes, the output voltage will not change suddenly.

[0006] However, the output current size of the constant current drive circuit of the prior art remains unchanged within a certain output voltage range. However, it is required that the load circuit connected to its output terminal has a suitable volt-ampere characteristic, that is, the voltage and current at both ends of the load have a corresponding variation relationship. When the load current is equal to the current value of the constant current drive circuit output, the corresponding load voltage value is the voltage value of the constant current drive circuit output. If the current of the load is less than the current of the constant current drive circuit output, the voltage of the constant current drive circuit output will increase. If the current of the load is greater than the current of the constant current drive circuit output, the voltage of the constant current drive circuit output will reduce.

[0007] The high color temperature light-emitting circuit and the low color temperature light-emitting circuit both have a positive electrode and a negative electrode, and are both LED light-emitting modules (such as the high color temperature light-emitting circuit includes a group of cold color temperature LED lamp beads, and the low color temperature light-emitting circuit includes a group of warm color temperature LED lamp beads).

[0008] The color temperature control circuit in the prior art has two output terminals (a first output terminal and a second output terminal), a PWM control terminal and a negative electrode.

[0009] The positive pole of the constant current driving circuit is connected to the positive pole of the high color temperature LED circuit and the positive pole of the low color temperature light-emitting circuit, the negative pole of the high color temperature LED circuit is connected to the first output end of the color temperature control circuit, and the negative pole of the low color temperature light-emitting circuit is connected to the second output end of the color temperature control circuit.

[0010] The PWM control end of the color temperature control circuit is connected to the 1 level and 0 level control of the PWM signal, and the first output end and the negative electrode of the color temperature control circuit and the second output end and the negative electrode are time-sharingly connected. When the first output end is turned on, the second output end is turned off, and vice versa, when the first output end is turned off, the second output end is turned on. The conduction time of the two ports corresponds to the 1 level time and the 0 level time of the PWM signal respectively.

[0011] When the PWM signal is not constantly at 1 or constantly at 0, both the high color temperature light-emitting circuit and the low color temperature light-emitting circuit will have periodic changes in brightness and darkness. In addition, the output current of the constant current drive circuit also has periodic changes in current size, and its frequency of change is twice the frequency of change of the AC voltage of the mains. Therefore, the overall LED light-emitting circuit will inevitably produce flicker, affecting the light-emitting quality of the LED light-emitting circuit.

[0012] As users have higher and higher requirements on the light quality of LED lamps, the flicker index of dimming and color-adjusting LED lamps has also become an important index. Therefore, the existing driving circuit technology of dimming and color-adjusting LED lamps needs to be improved. Summary of the invention

[0013] The purpose of the present invention is to overcome the deficiencies of the prior art and to provide a color temperature control circuit with a low ripple output current and a driving circuit for a dimming LED lamp.

[0014] The present invention adopts the following technical solution:

[0015] On the one hand, the present invention provides a color temperature control circuit, comprising: a voltage conversion circuit, a first signal conversion circuit, a second signal conversion circuit, an inverter circuit, a first voltage-controlled constant current circuit and a second voltage-controlled constant current circuit; the voltage conversion circuit is connected to the first voltage-controlled constant current circuit and the second voltage-controlled constant current circuit, respectively, and is used to convert the lower voltage of the output terminal voltage of the first voltage-controlled constant current circuit and the output terminal voltage of the second voltage-controlled constant current circuit into a DC voltage, and output it to the first signal conversion circuit and the second signal conversion circuit; the first signal conversion circuit is connected to the voltage conversion circuit and the dimming control circuit, respectively, and is used to convert the color temperature adjustment PWM signal output by the dimming control circuit and the DC voltage signal output by the voltage conversion circuit into a corresponding DC voltage, and output it to the first signal conversion circuit. A voltage-controlled constant current circuit; the inverter circuit is connected to the dimming control circuit, and is used to invert the color temperature adjustment PWM signal output by the dimming control circuit and output it to the second signal conversion circuit; the second signal conversion circuit is connected to the voltage conversion circuit and the inverter circuit respectively, and is used to convert the PWM signal output by the inverter circuit and the DC voltage signal output by the voltage conversion circuit into corresponding DC voltages, and output them to the second voltage-controlled constant current circuit; the first voltage-controlled constant current circuit is connected to the first signal conversion circuit to control the maximum conduction current value between the output end and the negative pole of the first voltage-controlled constant current circuit; the second voltage-controlled constant current circuit is connected to the second signal conversion circuit to control the maximum conduction current value between the output end and the negative pole of the first voltage-controlled constant current circuit.

[0016] Preferably, the voltage conversion circuit includes a first resistor, a second resistor, a third resistor, a first voltage-regulating diode, a second voltage-regulating diode and a first capacitor; one end of the first resistor is connected to the positive electrode of the color temperature control circuit, and the positive electrode of the color temperature control circuit is connected to the positive output end of the constant current drive circuit; the other end of the first resistor is respectively connected to the anode of the first voltage-regulating diode, the anode of the second voltage-regulating diode, and one end of the second resistor; the cathode of the first voltage-regulating diode is connected to the output end of the first voltage-controlled constant current circuit; the cathode of the second voltage-regulating diode is connected to the output end of the second voltage-controlled constant current circuit; the other end of the second resistor is respectively connected to one end of the first capacitor and one end of the third resistor; the other end of the first capacitor and the other end of the third resistor are connected to the negative electrode of the voltage conversion circuit.

[0017] Preferably, the first signal conversion circuit includes a third diode, a fourth resistor, a fifth resistor and a second capacitor; the cathode of the third diode is connected to the color temperature adjustment PWM signal output by the dimming control circuit; the anode of the third diode is connected to one end of the fourth resistor; the other end of the fourth resistor is respectively connected to one end of the fifth resistor and one end of the second capacitor; the other end of the fifth resistor is connected to the output end of the voltage conversion circuit; the other end of the second capacitor is connected to the negative electrode of the first signal conversion circuit.

[0018] Preferably, the inverter circuit includes a third MOS tube; the gate of the third MOS tube is connected to the color temperature adjustment PWM signal output by the dimming control circuit; the drain of the third MOS tube is connected to the second signal conversion circuit; and the source of the third MOS tube is connected to the negative electrode of the inverter circuit.

[0019] Preferably, the second signal conversion circuit includes a fourth diode, a sixth resistor, a seventh resistor and a third capacitor; the cathode of the fourth diode is connected to the output end of the inverter circuit; the anode of the fourth diode is connected to one end of the seventh resistor; the other end of the seventh resistor is respectively connected to one end of the sixth resistor and one end of the third capacitor; the other end of the sixth resistor is connected to the output end of the voltage conversion circuit; the other end of the third capacitor is connected to the negative electrode of the second signal conversion circuit.

[0020] Preferably, the first voltage-controlled constant current circuit includes a first MOS tube and an eighth resistor; the gate of the first MOS tube is connected to the output end of the first signal conversion circuit; the source of the first MOS tube is connected to one end of the eighth resistor; the drain of the first MOS tube is respectively connected to the high color temperature light-emitting circuit and the voltage conversion circuit; the other end of the eighth resistor is connected to the negative electrode of the first voltage-controlled constant current circuit.

[0021] Preferably, the second voltage-controlled constant current circuit includes a second MOS tube and a ninth resistor; the gate of the second MOS tube is connected to the output end of the second signal conversion circuit; the source of the second MOS tube is connected to one end of the ninth resistor; the drain of the second MOS tube is respectively connected to the low color temperature light-emitting circuit and the voltage conversion circuit; the other end of the ninth resistor is connected to the negative electrode of the second voltage-controlled constant current circuit.

[0022] Preferably, the negative electrode of the voltage conversion circuit, the negative electrode of the first signal conversion circuit, the negative electrode of the second signal conversion circuit, the negative electrode of the inverter circuit, the negative electrode of the first voltage-controlled constant current circuit and the negative electrode of the second voltage-controlled constant current circuit are all interconnected, and the interconnected connection end is the negative electrode of the color temperature control circuit.

[0023] On the other hand, the present invention provides a driving circuit for a dimming LED lamp, comprising a constant current driving circuit, a dimming control circuit, a low color temperature light-emitting circuit and a high color temperature light-emitting circuit; and also comprising the color temperature control circuit; the positive output end of the constant current driving circuit is respectively connected to the positive electrode of the high color temperature light-emitting circuit and the positive electrode of the low color temperature light-emitting circuit; the negative electrode of the high color temperature light-emitting circuit is connected to the first output end of the color temperature control circuit; the negative electrode of the low color temperature light-emitting circuit is connected to the second output end of the color temperature control circuit; the negative electrode of the color temperature control circuit is connected to the negative output end of the constant current driving circuit; the brightness adjustment PWM signal output end of the dimming control circuit is connected to the control end of the constant current driving circuit; the color temperature adjustment PWM signal output end of the dimming control circuit is connected to the control end of the color temperature control circuit; wherein the first output end of the color temperature control circuit is the output end of the first voltage-controlled constant current circuit; and the second output end of the color temperature control circuit is the output end of the second voltage-controlled constant current circuit.

[0024] Preferably, the positive electrode of the color temperature control circuit is connected to the positive output end of the constant current driving circuit.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) The color temperature control circuit of the present invention has the function of adaptively adjusting the total current of its first output terminal and the second output terminal, that is, it has the function of adaptively adjusting its own volt-ampere characteristic; the color temperature control circuit detects the lower voltage of the first output terminal and the second output terminal, compares the detected lower voltage with the threshold voltage (the threshold voltage of the first MOS tube or the second MOS tube, that is, the lowest voltage to keep the drain current constant), and when the lower voltage is greater than the threshold voltage, the total current of the first output terminal and the second output terminal is rapidly increased, and when the lower voltage is less than the threshold voltage, the total current of the first output terminal and the second output terminal is rapidly reduced, so that when the total current flowing through the first output terminal and the second output terminal is equal to the current output by the constant current driving circuit, the detected lower voltage value is kept near the threshold voltage; the color temperature control circuit is compatible with the currents of different magnitudes output by the constant current driving circuit, while maintaining low power consumption;

[0027] (2) When the color temperature control circuit of the present invention is connected to different color temperature adjustment PWM signals, the current size ratio between the first output terminal and the second output terminal corresponds to the color temperature adjustment PWM signal. When the constant current drive circuit outputs currents of different sizes and the total current of the first output terminal and the second output terminal of the color temperature control circuit changes, the size ratio and the corresponding relationship of the color temperature adjustment PWM signal remain unchanged; and the current flowing through the first output terminal and the current flowing through the second output terminal are both low-ripple DC currents, the high color temperature light-emitting circuit and the low color temperature light-emitting circuit are both low-frequency flickering light, and the light emission of the color-adjustable dimming LED lamp is also maintained in a low-frequency flickering state.

[0028] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention so that it can be implemented in accordance with the contents of the specification, and in order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below.

[0029] Based on the following detailed description of specific embodiments of the present invention in conjunction with the accompanying drawings, those skilled in the art will become more aware of the above and other objects, advantages and features of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a structural block diagram of a driving circuit of a dimming LED lamp according to an embodiment of the present invention;

[0031] Figure 2 is a structural block diagram of a color temperature control circuit according to an embodiment of the present invention;

[0032] Figure 3 4 is a color temperature control circuit diagram of an embodiment of the present invention. DETAILED DESCRIPTION

[0033] To make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0034] See also Figure 1As shown, a driving circuit of a dimming LED lamp of the present invention comprises a constant current driving circuit 20, a dimming control circuit 30, a color temperature control circuit 10, a low color temperature light-emitting circuit 40 and a high color temperature light-emitting circuit 50; the positive output end of the constant current driving circuit 20 is connected to the positive electrode of the high color temperature light-emitting circuit 50 and the positive electrode of the low color temperature light-emitting circuit 40 respectively; the negative electrode of the high color temperature light-emitting circuit 50 is connected to the first output end Out1 of the color temperature control circuit 10; the negative electrode of the low color temperature light-emitting circuit 40 is connected to the second output end Out2 of the color temperature control circuit 10; The negative electrode of the color temperature control circuit 10 is connected to the negative output end of the constant current drive circuit 20; the brightness adjustment PWM signal (PWM1) output end of the dimming control circuit 30 is connected to the control end of the constant current drive circuit 20; the color temperature adjustment PWM signal (PWM2) output end of the dimming control circuit 30 is connected to the control end of the color temperature control circuit 10; wherein, the first output end of the color temperature control circuit 10 is the output end of the first voltage-controlled constant current circuit 105; the second output end of the color temperature control circuit 10 is the output end of the second voltage-controlled constant current circuit 106.

[0035] If the color temperature control circuit 10 includes a positive electrode, the positive electrode of the color temperature control circuit 10 is connected to the positive output terminal of the constant current driving circuit 20 .

[0036] See also Figure 2 and Figure 3As shown, the color temperature control circuit 10 includes: a voltage conversion circuit 101, a first signal conversion circuit 102, a second signal conversion circuit 103, an inverter circuit 104, a first voltage-controlled constant current circuit 105 and a second voltage-controlled constant current circuit 106; the voltage conversion circuit 101 is connected to the first voltage-controlled constant current circuit 105 and the second voltage-controlled constant current circuit 106 respectively, and is used to convert the lower voltage of the output terminal voltage of the first voltage-controlled constant current circuit 105 and the output terminal voltage of the second voltage-controlled constant current circuit 106 detected into a DC voltage, and output it to the first signal conversion circuit 102 and the second signal conversion circuit 103; the first signal conversion circuit 102 is connected to the voltage conversion circuit 101 and the dimming control circuit 30 respectively, and is used to convert the color temperature adjustment PWM signal output by the dimming control circuit 30 and the DC voltage signal output by the voltage conversion circuit 101 into a corresponding DC voltage, and output it to the A first voltage-controlled constant current circuit 105; the inverter circuit 104 is connected to the dimming control circuit 30, and is used to invert the color temperature adjustment PWM signal output by the dimming control circuit 30 and output it to the second signal conversion circuit 103; the second signal conversion circuit 103 is connected to the voltage conversion circuit 101 and the inverter circuit 104 respectively, and is used to convert the PWM signal output by the inverter circuit 104 and the DC voltage signal output by the voltage conversion circuit 101 into corresponding DC voltages, and output them to the second voltage-controlled constant current circuit 106; the first voltage-controlled constant current circuit 105 is connected to the first signal conversion circuit 102 for controlling the maximum conduction current value between the output end and the negative electrode of the first voltage-controlled constant current circuit 105; the second voltage-controlled constant current circuit 106 is connected to the second signal conversion circuit 103 for controlling the maximum conduction current value between the output end and the negative electrode of the first voltage-controlled constant current circuit 105.

[0037] Specifically, the voltage conversion circuit 101 includes a first detection terminal, a second detection terminal and an output terminal. The first signal conversion circuit 102 includes a first input terminal, a second input terminal, a cathode and an output terminal. The second signal conversion circuit 103 includes a first input terminal, a second input terminal, a cathode and an output terminal. The inverter circuit 104 includes an input terminal and an output terminal. The first voltage-controlled constant current circuit 105 includes a control terminal, an output terminal and a cathode.

[0038] The first detection end of the voltage conversion circuit 101 is connected to the output end of the first voltage-controlled constant current circuit 105; the second detection end is connected to the output end of the second voltage-controlled constant current circuit 106; the output end of the voltage conversion circuit 101 is respectively connected to the first input end of the first signal conversion circuit 102 and the first input end of the second signal conversion circuit 103; it is used to convert the lower voltage between the voltage detected by the first detection end and the voltage detected by the second detection end into a DC voltage, and output it to the first signal conversion circuit 102 and the second signal conversion circuit 103.

[0039] The voltage conversion circuit 101 has a voltage at the first detection terminal and a voltage at the second detection terminal, and the lower voltage (the voltage at the first detection terminal and the voltage at the second detection terminal is smaller) and a threshold voltage (corresponding to Figure 3 , which is the threshold voltage of the MOS tube, that is, the lowest voltage that keeps the drain current unchanged), the lower the lower voltage is, the lower the output voltage is; the higher the lower voltage is, the higher the output voltage is.

[0040] The second input terminal of the first signal conversion circuit 102 is connected to the color temperature adjustment PWM signal output by the dimming control circuit 30; the output terminal of the first signal conversion circuit 102 is connected to the control terminal of the first voltage-controlled constant current circuit 105; it is used to convert the color temperature adjustment PWM signal output by the dimming control circuit 30 at the second input terminal and the DC voltage signal at the first input terminal into a corresponding DC voltage, and output it to the first voltage-controlled constant current circuit 105. The DC voltage output by the first signal conversion circuit 102 to the first voltage-controlled constant current circuit 105 is proportional to the product of the duty cycle of the color temperature adjustment PWM signal 1 level and the DC voltage signal output by the voltage conversion circuit 101.

[0041] The input end of the inverter circuit 104 is connected to the color temperature adjustment PWM signal output by the dimming control circuit 30, and the output end of the inverter circuit 104 is connected to the second input end of the second signal conversion circuit 103; it is used to invert the color temperature adjustment PWM signal output by the dimming control circuit 30 and then output it to the second signal conversion circuit 103. The level of the input end and the level of the output end of the inverter circuit 104 remain opposite, that is, when the input end is at 0 level, the output end is at 1 level, and when the input end is at 1 level, the output end is at 0 level.

[0042] The second input terminal of the second signal conversion circuit 103 is connected to the output terminal of the inverter circuit 104; the output terminal of the second signal conversion circuit 103 is connected to the control terminal of the second voltage-controlled constant current circuit 106; it is used to convert the second input terminal signal and the DC voltage signal of the first input terminal into a corresponding DC voltage, and output it to the second voltage-controlled constant current circuit 106. The DC voltage output by the second signal conversion circuit 103 to the second voltage-controlled constant current circuit 106 is proportional to the product of the duty cycle of the color temperature adjustment PWM signal 0 level and the DC voltage signal output by the voltage conversion circuit 101.

[0043] The control end of the first voltage-controlled constant current circuit 105 is connected to the output end of the first signal conversion circuit 102 and is used to control the maximum conduction current value between the output end and the negative electrode of the first voltage-controlled constant current circuit 105 .

[0044] The control end of the second voltage-controlled constant current circuit 106 is connected to the output end of the second signal conversion circuit 103 and is used to control the maximum conduction current value between the output end and the negative electrode of the second voltage-controlled constant current circuit 106 .

[0045] As long as the voltage at the output end of the first voltage-controlled constant current circuit 105 or the output end of the second voltage-controlled constant current circuit 106 is greater than or equal to the threshold voltage, the current at the output end of the first voltage-controlled constant current circuit 105 or the output end of the second voltage-controlled constant current circuit 106 corresponds to the voltage at its control end. The higher the voltage at the control end, the greater the current at the output end.

[0046] Furthermore, the negative electrode of the voltage conversion circuit 101, the negative electrode of the first signal conversion circuit 102, the negative electrode of the second signal conversion circuit 103, the negative electrode of the inverter circuit 104, the negative electrode of the first voltage-controlled constant current circuit 105 and the negative electrode of the second voltage-controlled constant current circuit 106 are all interconnected, and the interconnected connection end is the negative electrode of the color temperature control circuit 10.

[0047] As can be seen from the above, in the color temperature control circuit 10 of the present invention, when the current output by the constant current driving circuit 20 remains unchanged, the voltage conversion circuit 101 detects the lower voltage value of the output terminal voltage of the first voltage-controlled constant current circuit 105 and the output terminal voltage of the second voltage-controlled constant current circuit 106 in real time, and adjusts the output voltage size so that the total current of the output terminal of the first voltage-controlled constant current circuit 105 and the output terminal of the second voltage-controlled constant current circuit 106 is equal to the current output by the constant current driving circuit 20, and the lower voltage of the two output terminals is maintained at a balance point near the threshold voltage.

[0048] If the voltage conversion circuit 101 detects in real time that the lower voltage value of the output terminal voltage of the first voltage-controlled constant current circuit 105 and the output terminal voltage of the second voltage-controlled constant current circuit 106 is lower than the voltage threshold and deviates from the equilibrium point, then the output voltage of the voltage conversion circuit 101 decreases, and the voltage output by the first signal conversion circuit 102 and the second signal conversion circuit 103 decreases, and the current at the output terminal of the first voltage-controlled constant current circuit 105 and the output terminal of the second voltage-controlled constant current circuit 106 is controlled to decrease until the lower voltage at the output terminal of the first voltage-controlled constant current circuit 105 and the output terminal of the second voltage-controlled constant current circuit 106 no longer decreases, and a new equilibrium point is reached.

[0049] If the voltage conversion circuit 101 detects in real time that the lower voltage value of the output voltage of the first voltage-controlled constant current circuit 105 and the output voltage of the second voltage-controlled constant current circuit 106 is higher than the voltage threshold and deviates from the equilibrium point, then the output voltage of the voltage conversion circuit 101 increases, and the voltage output by the first signal conversion circuit 102 and the second signal conversion circuit 103 increases, and the current at the output end of the first voltage-controlled constant current circuit 105 and the output end of the second voltage-controlled constant current circuit 106 is controlled to increase until the lower voltage at the output end of the first voltage-controlled constant current circuit 105 and the output end of the second voltage-controlled constant current circuit 106 no longer increases and reaches a new equilibrium point.

[0050] When the current output by the constant current driving circuit 20 remains unchanged, the output voltage of the first signal conversion circuit 102 corresponds to the duty cycle of the 1-level PWM2 control signal connected to the color temperature control circuit 10, and the output voltage of the second signal conversion circuit 103 corresponds to the duty cycle of the 1-level signal output by the inverter circuit, that is, the output voltage of the second signal conversion circuit 103 corresponds to the duty cycle of the 0-level PWM2 control signal connected to the color temperature control circuit 10. The output voltage of the first signal conversion circuit 102 and the output voltage of the second signal conversion circuit 103 are both related to the DC voltage signal output by the voltage conversion circuit 101.

[0051] The current magnitude at the output end of the first voltage-controlled constant current circuit 105 corresponds to the 1-level duty cycle of PWM2, and the current magnitude at the output end of the second voltage-controlled constant current circuit 106 corresponds to the 0-level duty cycle of PWM2. If the signal of PWM2 changes, the magnitude ratio of the current at the first output end and the current at the second output end of the color temperature control circuit 10 also changes with the change of the time ratio of the 1-level and 0-level of the PWM2 signal.

[0052] When the color temperature control signal PWM2 remains unchanged, when the constant current driving circuit 20 increases the output current due to brightness adjustment, the current output by the constant current driving circuit 20 increases, deviating from the balance point where the output current is equal to the load current, so the lower voltage at the output end of the first voltage-controlled constant current circuit 105 and the output end of the second voltage-controlled constant current circuit 106 increases. The output DC voltage of the voltage conversion circuit 101 increases, so that the output voltage of the first signal conversion circuit 102 and the output voltage of the second signal conversion circuit 103 both increase, and the current at the output end of the first voltage-controlled constant current circuit 105 and the current at the output end of the second voltage-controlled constant current circuit 106 also increase at the same time, until the lower voltage at the output end of the first voltage-controlled constant current circuit 105 and the output end of the second voltage-controlled constant current circuit 106 no longer increase, and a new balance point is reached.

[0053] When the color temperature control signal PWM2 remains unchanged, when the constant current drive circuit 20 decreases its output current due to brightness adjustment, the current output by the constant current drive circuit 20 decreases, deviating from the balance point where the output current is equal to the load current. Therefore, the lower voltage at the first output terminal and the second output terminal of the color temperature control circuit 10 decreases, and the output DC voltage of the voltage conversion circuit 101 decreases, so that the output voltage of the first signal conversion circuit 102 and the output voltage of the second signal conversion circuit 103 are both reduced. Then, the current at the output terminal of the first voltage-controlled constant current circuit 105 and the current at the output terminal of the second voltage-controlled constant current circuit 106 also decrease at the same time, until the lower voltage at the output terminal of the first voltage-controlled constant current circuit 105 and the output terminal of the second voltage-controlled constant current circuit 106 no longer decreases, and a new balance point is reached.

[0054] The color temperature control circuit 10 of the present invention is characterized in that the size of the control voltage is adjusted through the internal circuit, and the size of the current at the first output terminal and the current at the second output terminal are adjusted at the same time, so that the lower voltage at the first output terminal and the second output terminal is maintained near the threshold voltage, thereby achieving compatibility of the color temperature control circuit 10 with currents of different sizes output by the constant current drive circuit 20 while maintaining low power consumption.

[0055] By converting the PWM pulse signal into a DC voltage, the current at the first output terminal or the second output terminal is controlled to be a stable DC current. While the high color temperature light emitting circuit 50 and the low color temperature light emitting circuit 40 are respectively in a low-frequency flickering light emitting state, their total light intensity is also in a low-frequency flickering light emitting state.

[0056] In the following examples, the voltage conversion circuit 101 has a positive electrode, which serves as the positive electrode of the color temperature control circuit 10 and is connected to the positive output terminal of the constant current driving circuit 20 .

[0057] Specifically, the voltage conversion circuit 101 includes a first resistor R1, a second resistor R2, a third resistor R3, a first voltage zener diode D1, a second voltage zener diode D2 and a first capacitor C1; one end of the first resistor R1 is connected to the positive electrode V+ of the color temperature control circuit 10, and the positive electrode of the color temperature control circuit 10 is connected to the positive output end of the constant current drive circuit 20; the other end of the first resistor R1 is connected to the anode of the first voltage zener diode D1, the anode of the second voltage zener diode D2, and one end of the second resistor R2 respectively; the cathode of the first voltage zener diode D1 is connected to the output end of the first voltage-controlled constant current circuit 105; the cathode of the second voltage zener diode D2 is connected to the output end of the second voltage-controlled constant current circuit 106; the other end of the second resistor R2 is connected to one end of the first capacitor C1 and one end of the third resistor R3 respectively; the other end of the first capacitor C1 and the other end of the third resistor R3 are connected to the negative electrode of the voltage conversion circuit 101. The first voltage stabilizing diode D1 clamps the voltage at the output end of the first voltage-controlled constant current circuit 105, and the second voltage stabilizing diode D2 clamps the voltage at the output end of the second voltage-controlled constant current circuit 106. The first capacitor C1 is used for filtering.

[0058] The first signal conversion circuit 102 includes a third diode D3, a fourth resistor R4, a fifth resistor R5, and a second capacitor C2; the cathode of the third diode D3 is connected to the color temperature adjustment PWM signal output by the dimming control circuit; the anode of the third diode D3 is connected to one end of the fourth resistor R4; the other end of the fourth resistor R4 is connected to one end of the fifth resistor R5 and one end of the second capacitor C2 respectively; the other end of the fifth resistor R5 is connected to the output end of the voltage conversion circuit 101; the other end of the second capacitor C2 is connected to the negative electrode of the first signal conversion circuit 102. The second capacitor C2 is used for filtering.

[0059] The inverter circuit 104 includes a third MOS tube Q3; the gate of the third MOS tube Q3 is connected to the color temperature adjustment PWM signal output by the dimming control circuit; the drain of the third MOS tube Q3 is connected to the second signal conversion circuit 103; the source of the third MOS tube Q3 is connected to the cathode of the inverter circuit 104.

[0060] The second signal conversion circuit 103 includes a fourth diode D4, a sixth resistor R6, a seventh resistor R7 and a third capacitor C3; the cathode of the fourth diode D4 is connected to the output end of the inverter circuit 104; the anode of the fourth diode D4 is connected to one end of the seventh resistor R7; the other end of the seventh resistor R7 is connected to one end of the sixth resistor R6 and one end of the third capacitor C3 respectively; the other end of the sixth resistor R6 is connected to the output end of the voltage conversion circuit 101; the other end of the third capacitor C3 is connected to the negative electrode of the second signal conversion circuit 103. The third capacitor C3 is used for filtering.

[0061] The first voltage-controlled constant current circuit 105 includes a first MOS tube Q1 and an eighth resistor R8; the gate of the first MOS tube Q1 is connected to the output end of the first signal conversion circuit 102; the source of the first MOS tube Q1 is connected to one end of the eighth resistor R8; the drain of the first MOS tube Q1 is connected to the high color temperature light-emitting circuit 50 and the voltage conversion circuit 101 respectively; the other end of the eighth resistor R8 is connected to the negative electrode of the first voltage-controlled constant current circuit 105.

[0062] The second voltage-controlled constant current circuit 106 includes a second MOS tube Q2 and a ninth resistor R9; the gate of the second MOS tube Q2 is connected to the output end of the second signal conversion circuit 103; the source of the second MOS tube Q2 is connected to one end of the ninth resistor R9; the drain of the second MOS tube Q2 is connected to the low color temperature light-emitting circuit 40 and the voltage conversion circuit 101 respectively; the other end of the ninth resistor R9 is connected to the negative electrode of the second voltage-controlled constant current circuit 106.

[0063] The above is only a specific implementation of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial changes to the present invention using this concept shall be deemed as an infringement of the protection scope of the present invention.

Claims

1. A color temperature control circuit, characterized in that: include: A voltage conversion circuit, a first signal conversion circuit, a second signal conversion circuit, an inverter circuit, a first voltage-controlled constant current circuit, and a second voltage-controlled constant current circuit; The voltage conversion circuit is connected to the first voltage-controlled constant current circuit and the second voltage-controlled constant current circuit respectively, and is used to convert the lower voltage of the output terminal voltage of the first voltage-controlled constant current circuit and the output terminal voltage of the second voltage-controlled constant current circuit into a DC voltage, and output it to the first signal conversion circuit and the second signal conversion circuit; the first signal conversion circuit is connected to the voltage conversion circuit and the dimming control circuit respectively, and is used to convert the color temperature adjustment PWM signal output by the dimming control circuit and the DC voltage signal output by the voltage conversion circuit into corresponding DC voltages, and output them to the first voltage-controlled constant current circuit; the inverter circuit is connected to the dimming control circuit, and is used to convert the dimming control circuit into a corresponding DC voltage. The color temperature adjustment PWM signal output by the first voltage-controlled constant current circuit is inverted and output to the second signal conversion circuit; the second signal conversion circuit is connected to the voltage conversion circuit and the inverter circuit respectively, and is used to convert the PWM signal output by the inverter circuit and the DC voltage signal output by the voltage conversion circuit into corresponding DC voltages, and output them to the second voltage-controlled constant current circuit; the first voltage-controlled constant current circuit is connected to the first signal conversion circuit for controlling the maximum conduction current value between the output end and the negative electrode of the first voltage-controlled constant current circuit; the second voltage-controlled constant current circuit is connected to the second signal conversion circuit for controlling the maximum conduction current value between the output end and the negative electrode of the first voltage-controlled constant current circuit.

2. The color temperature control circuit according to claim 1, characterized in that: The voltage conversion circuit includes a first resistor, a second resistor, a third resistor, a first voltage-regulating diode, a second voltage-regulating diode and a first capacitor; one end of the first resistor is connected to the positive electrode of the color temperature control circuit, and the positive electrode of the color temperature control circuit is connected to the positive output end of the constant current drive circuit; the other end of the first resistor is respectively connected to the anode of the first voltage-regulating diode, the anode of the second voltage-regulating diode, and one end of the second resistor; the cathode of the first voltage-regulating diode is connected to the output end of the first voltage-controlled constant current circuit; the cathode of the second voltage-regulating diode is connected to the output end of the second voltage-controlled constant current circuit; the other end of the second resistor is respectively connected to one end of the first capacitor and one end of the third resistor; the other end of the first capacitor and the other end of the third resistor are connected to the negative electrode of the voltage conversion circuit.

3. The color temperature control circuit according to claim 1, characterized in that: The first signal conversion circuit includes a third diode, a fourth resistor, a fifth resistor and a second capacitor; the cathode of the third diode is connected to the color temperature adjustment PWM signal output by the dimming control circuit; the anode of the third diode is connected to one end of the fourth resistor; the other end of the fourth resistor is respectively connected to one end of the fifth resistor and one end of the second capacitor; the other end of the fifth resistor is connected to the output end of the voltage conversion circuit; the other end of the second capacitor is connected to the negative electrode of the first signal conversion circuit.

4. The color temperature control circuit according to claim 1, characterized in that: The inverter circuit includes a third MOS tube; the gate of the third MOS tube is connected to the color temperature adjustment PWM signal output by the dimming control circuit; the drain of the third MOS tube is connected to the second signal conversion circuit; and the source of the third MOS tube is connected to the negative electrode of the inverter circuit.

5. The color temperature control circuit according to claim 1, characterized in that: The second signal conversion circuit includes a fourth diode, a sixth resistor, a seventh resistor and a third capacitor; the cathode of the fourth diode is connected to the output end of the inverter circuit; the anode of the fourth diode is connected to one end of the seventh resistor; the other end of the seventh resistor is connected to one end of the sixth resistor and one end of the third capacitor respectively; the other end of the sixth resistor is connected to the output end of the voltage conversion circuit; the other end of the third capacitor is connected to the negative electrode of the second signal conversion circuit.

6. The color temperature control circuit according to claim 1, characterized in that: The first voltage-controlled constant current circuit includes a first MOS tube and an eighth resistor; the gate of the first MOS tube is connected to the output end of the first signal conversion circuit; the source of the first MOS tube is connected to one end of the eighth resistor; the drain of the first MOS tube is connected to the high color temperature light-emitting circuit and the voltage conversion circuit respectively; the other end of the eighth resistor is connected to the negative electrode of the first voltage-controlled constant current circuit.

7. The color temperature control circuit according to claim 1, characterized in that: The second voltage-controlled constant current circuit includes a second MOS tube and a ninth resistor; the gate of the second MOS tube is connected to the output end of the second signal conversion circuit; the source of the second MOS tube is connected to one end of the ninth resistor; the drain of the second MOS tube is connected to the low color temperature light-emitting circuit and the voltage conversion circuit respectively; the other end of the ninth resistor is connected to the negative electrode of the second voltage-controlled constant current circuit.

8. The color temperature control circuit according to claim 1, characterized in that: The negative electrode of the voltage conversion circuit, the negative electrode of the first signal conversion circuit, the negative electrode of the second signal conversion circuit, the negative electrode of the inverter circuit, the negative electrode of the first voltage-controlled constant current circuit and the negative electrode of the second voltage-controlled constant current circuit are all interconnected, and the interconnected connection end is the negative electrode of the color temperature control circuit.

9. A driving circuit for a color-dimming LED lamp, comprising a constant current driving circuit, a dimming control circuit, a low color temperature light-emitting circuit and a high color temperature light-emitting circuit; characterized in that: It also includes the color temperature control circuit as described in any one of claims 1 to 8; the positive output end of the constant current drive circuit is connected to the positive electrode of the high color temperature light-emitting circuit and the positive electrode of the low color temperature light-emitting circuit respectively; the negative electrode of the high color temperature light-emitting circuit is connected to the first output end of the color temperature control circuit; the negative electrode of the low color temperature light-emitting circuit is connected to the second output end of the color temperature control circuit; the negative electrode of the color temperature control circuit is connected to the negative output end of the constant current drive circuit; the brightness adjustment PWM signal output end of the dimming control circuit is connected to the control end of the constant current drive circuit; the color temperature adjustment PWM signal output end of the dimming control circuit is connected to the control end of the color temperature control circuit; wherein the first output end of the color temperature control circuit is the output end of the first voltage-controlled constant current circuit; the second output end of the color temperature control circuit is the output end of the second voltage-controlled constant current circuit.

10. The driving circuit of the dimming LED lamp according to claim 9, characterized in that: The positive electrode of the color temperature control circuit is connected to the positive output end of the constant current driving circuit.

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