CN105657932B - Light source driving circuit and brightness and color-temperature controller - Google Patents

Abstract

The invention discloses a light source drive circuit and a brightness and color temperature controller. The light source driving circuit is used to adjust the brightness and color temperature of the light source, and includes a power converter and a brightness and color temperature controller coupled to the power converter. A power converter is coupled between the power source and the light source for receiving power from the power source and providing conditioned power to the light source. The brightness and color temperature controller is configured to receive a conduction detection signal indicative of a conduction state of a triac dimmer coupled between the power supply and the power converter, and adjust the brightness of the light source based on the conduction detection signal. The brightness and color temperature controller is also configured to receive a switch monitor signal indicative of operation of an on/off switch coupled to the triac dimmer and to adjust the color temperature of the light source based on the switch monitor signal. The invention realizes the adjustment of the brightness and color temperature of the light source at the same time through the operation of the power switch, without using additional special devices, which is simple, convenient and cost-saving.

Description

Light source driving circuit and brightness and color temperature controller

technical field

The invention relates to the field of light sources, in particular to a light source driving circuit and a brightness and color temperature controller.

Background technique

In recent years, new light sources such as light-emitting diodes (light-emitting diodes, LEDs) have made progress in materials and manufacturing. LED has the characteristics of high efficiency, long life, bright colors, etc., and can be used in the fields of automobiles, computers, communications, military and daily necessities. For example, LED lamps can replace traditional incandescent lamps as lighting sources.

The light source can be adjusted in different ways. For example, a power converter receives an AC voltage from an AC power source and generates a DC voltage to power an LED light source. The controller adjusts the output of the power converter according to the dimmer coupled between the AC power source and the power converter, thereby adjusting the brightness of the LED light source. The dimmer may be a triac thyristor (TRIAC) dimmer or an ON/OFF dimmer. However, such dimmers can only be used to adjust the brightness of the light source but cannot adjust the color temperature of the light source.

Contents of the invention

The technical problem to be solved by the present invention is to provide a light source driving circuit and a brightness and color temperature controller, which can realize the adjustment of the brightness and color temperature of the light source in a simple and convenient manner.

In order to solve the above technical problems, the present invention provides a light source driving circuit for adjusting the brightness and color temperature of the light source. The light source drive circuit includes: a power converter coupled between a power source and the light source for receiving power from the power source and providing regulated power to the light source; and a brightness and color temperature controller coupled to the power source a converter for receiving a conduction detection signal indicative of a conduction state of a TRIAC dimmer coupled between the power source and the power converter, and adjusting brightness of the light source based on the conduction detection signal , wherein the brightness and color temperature controller is further configured to receive a switch monitor signal indicative of operation of an ON/OFF switch coupled to the TRIAC dimmer, and adjust the The color temperature of the light source.

The present invention also provides a brightness and color temperature controller, which includes: a signal generator for generating a monitoring signal proportional to the average current flowing through the light source; a TRIAC monitor for receiving indication a conduction detection signal of a conduction state of a TRIAC dimmer coupled between a power supply and a power converter and generating a reference signal indicative of a target value of an average current flowing through said light source based on said conduction detection signal; a driver , coupled to the signal generator and the TRIAC monitor, for generating a driving signal according to the monitoring signal and the reference signal to control the power converter to provide regulated power to the light source; and color temperature A control unit for receiving a switch monitoring signal indicative of operation of an ON/OFF switch coupled to the TRIAC dimmer, and adjusting the color temperature of the light source based on the switch monitoring signal.

Compared with the prior art, the light source driving circuit and the brightness and color temperature controller of the present invention can simultaneously realize the adjustment of the brightness and color temperature of the light source by operating the power switch (for example, including an ON/OFF switch and a TRIAC dimmer) , no need to use additional special devices, simple, convenient and cost-saving.

Description of drawings

The purpose, specific structural features and advantages of the present invention can be further understood through the description of some embodiments of the present invention in conjunction with the accompanying drawings.

FIG. 1A is a block diagram of a light source driving circuit according to an embodiment of the present invention;

FIG. 1B is a block diagram of a light source driving circuit including an ON/OFF switch and a TRIAC dimmer according to an embodiment of the present invention;

Fig. 1C is a waveform diagram of signals generated or received by the TRIAC dimmer in Fig. 1B;

Figure 2 is a schematic diagram of an embodiment of the power switch in Figure 1A and Figure 1B;

FIG. 3 is a schematic circuit diagram of a light source driving circuit according to an embodiment of the present invention;

FIG. 4 is a schematic structural diagram of the brightness and color temperature controller in FIG. 3;

Figure 5 shows a schematic structural view of the TRIAC monitor in Figure 4;

FIG. 6 is a schematic structural diagram of the color temperature control module in FIG. 4;

FIG. 7 is a signal waveform diagram of a light source driving circuit including the color temperature control module shown in FIG. 6 according to an embodiment of the present invention;

FIG. 8 is a signal waveform diagram of a light source driving circuit including the color temperature control module shown in FIG. 6 according to another embodiment of the present invention; and

Fig. 9 is a flowchart of a method for controlling the brightness and color temperature of a light source according to an embodiment of the present invention.

Detailed ways

Detailed reference will be given below to examples of the present invention. Although the present invention has been illustrated and illustrated by these embodiments, it should be noted that the present invention is not limited to these embodiments. On the contrary, the invention covers all alternatives, modifications and equivalents which are within the spirit and scope of the invention as defined by the appended claims.

In addition, in order to better illustrate the present invention, numerous specific details are given in the specific embodiments below. It will be understood by those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, components and circuits have not been described in detail so as not to obscure the gist of the present invention.

FIG. 1A is a block diagram of a light source driving circuit 100 according to an embodiment of the present invention. In one embodiment, the light source includes a first light emitting element (eg, first LED chain 120 ) and a second light emitting element (eg, second LED chain 130 ). The second LED chain 130 may have a different color temperature value than the first LED chain 120, for example, the first LED chain 120 has a first color temperature value and the second LED chain 130 has a second color temperature value. A power switch 101 coupled between the power V _IN and the light source driving circuit 100 includes an ON/OFF switch 102 (eg, a rocker switch) and a TRIAC dimmer 104 to selectively couple the power V _IN to the light source driving circuit 100 . It is worth noting that although ON/OFF switch 102 is coupled before TRIAC dimmer 104 in FIG. 1A , this is not limiting. For example, ON/OFF switch 102 may be coupled after TRIAC dimmer 104 as shown in FIG. 3 . In one embodiment, the power switch 101 may be a power switch placed on a wall. As shown in FIG. 2 , the power switch 101 is divided into a TRIAC dimmer 104 in the upper part and an ON/OFF switch 102 in the lower part. In operation, by switching the ON/OFF switch 102 to the ON terminal or the OFF terminal, the conduction state of the power switch 101 can be controlled by the user to be closed or open, and through the operation of the ON/OFF switch 102 (for example, an open operation ) to adjust the color temperature of the light source. At the same time, the user can also adjust the brightness of the light source by operating the TRIAC dimmer 104 (eg, knob operation).

The AC input voltage V _IN from the power source is converted into an AC voltage V _TRIAC via the ON/OFF switch 102 and the TRIAC dimmer 104 . The light source driver circuit 100 includes a rectifier 106 for converting an alternating voltage V _TRIAC to a rectified voltage V _REC , a power converter 108 coupled between the rectifier 106 and the light sources (e.g., first LED string 120 and second LED string 130 ). , a brightness and color temperature controller 112 , a first control switch 122 and a second control switch 132 . The power converter 108 is configured to receive the rectified voltage V _REC from the rectifier 106 and provide a regulated output current I _OUT to the light sources (eg, the first LED string 120 and the second LED string 130 ). The power converter 108 includes a transformer 110 having a primary winding and a secondary winding.

The brightness and color temperature controller 112 is coupled between the primary winding of the transformer 110 and the light sources (e.g., the first LED string 120 and the second LED string 130) for receiving instructions indicating the operation of the ON/OFF switch 102 (e.g., turning off operation) switch monitor signal TS, and adjust the color temperature of the light source (eg, the first LED chain 120 and the second LED chain 130 ) based on the switch monitor signal TS. As shown in FIG. 1A , the brightness and color temperature controller 112 generates a first control signal CTR1 and a second control signal CTR2 according to the switch monitoring signal TS to control the first LED chain 120 and the second LED chain 130 respectively.

The first control signal CTR1 selectively turns on the first control switch 122 coupled between the brightness and color temperature controller 112 and the first LED string 120 so that the color temperature of the light source is adjusted to a first color temperature value. The second control signal CTR2 selectively turns on the second control switch 132 coupled between the brightness and color temperature controller 112 and the second LED chain 130 so that the color temperature of the light source is adjusted to a second color temperature value. More specifically, if the first control signal CTR1 turns on the first control switch 122 coupled between the brightness and color temperature controller 112 and the first LED chain 120, the current I _LED1 flows through the first LED chain 120 and the light source's The color temperature is adjusted to the first color temperature value; if the second control signal CTR2 turns on the second control switch 132 coupled between the brightness and color temperature controller 112 and the second LED chain 130, the current I _LED2 flows through the second LED chain 130 and the color temperature of the light source is adjusted to the second color temperature value.

In addition, the brightness and color temperature controller 112 is also configured to receive a conduction detection signal TD indicating the conduction state of the TRIAC dimmer 104 (for example, a conduction angle between 0-180 degrees), and based on the conduction detection signal TD to adjust the brightness of the light source (for example, the value of current I _LED1 or current I _LED2 ). Specifically, the operation of adjusting brightness can be understood in conjunction with FIG. 1B and FIG. 1C , and FIG. 1B shows a block diagram of a light source driving circuit 100 including an ON/OFF switch 102 and a TRIAC dimmer 104 according to an embodiment of the present invention. As shown in FIG. 1B , TRIAC dimmer 104 includes TRIAC device 202 coupled between ON/OFF switch 102 and rectifier 106 . TRIAC device 202 has port A1 , port A2 and gate G . The TRIAC dimmer 104 further includes a variable resistor 204 and a capacitor 206 coupled in series, and a Diode for Alternating Current (DIAC) device 208 . One end of the DIAC device 208 is coupled to the capacitor 206 and the other end is coupled to the gate G of the TRIAC device 202 . TRIAC device 202 is a bi-directional switch that can conduct current in either direction once triggered. TRIAC device 202 can be triggered by positive or negative current applied to gate G. Once triggered, TRIAC device 202 will remain on until the current flowing through port A1 and port A2 falls below a threshold (eg, holding current I _H ).

FIG. 1C is a waveform diagram of signals generated or received by the TRIAC dimmer 104 in FIG. 1B according to an embodiment of the present invention. FIG. 1C will be described in conjunction with FIG. 1B. 1C shows the waveforms of the AC input voltage V _IN , the voltage V _A2-A1 between the ports A1 and A2 of the TRIAC device 202 , the current I _DIAC flowing through the DIAC device 208 , the AC voltage V _TRIAC and the rectified voltage V _REC .

In the example of FIG. 1C , the AC input voltage V _IN has a sinusoidal waveform. Between time T ₀ and time T ₁ , the TRIAC device 202 is turned off, and the voltage V _{A2 - A1} between the port A1 and the port A2 increases with the increase of the AC input voltage V _IN . From time _T1 to time _T2 , the TRIAC device 202 remains on. Therefore, between the time _T1 and the time _T2 , the waveform of the AC voltage V _TRIAC is consistent with the waveform of the AC input voltage V _IN .

At time T ₂ near the end of the first half cycle of the AC input voltage V _IN , the TRIAC device 202 turns off because the current through the TRIAC device 202 drops below the holding current of the TRIAC device 202 . During the second half cycle of the AC input voltage V _IN , when the voltage on the capacitor 206 turns on the DIAC device 208 at time T ₃ , the TRIAC device 202 turns on again. Similarly, between time _T3 and time _T4 , the waveform of the AC voltage V _TRIAC is consistent with the waveform of the AC input voltage V _IN .

In one embodiment, the user can adjust the resistance R ₂₀₄ of the variable resistor 204 , for example, by turning the knob of the TRIAC dimmer 104 to adjust the resistance R 204 of the variable resistor ₂₀₄ . The resistance R ₂₀₄ of the variable resistor 204 determines the conduction moment of the TRIAC device 202 in each half cycle of the AC input voltage V _IN . More specifically, in one embodiment, if the resistance value R ₂₀₄ of the variable resistor increases, the average value of the charging current for charging the capacitor 206 after time T ₀ decreases. Therefore, the voltage on capacitor 206 takes more time to reach the voltage threshold associated with DIAC device 208 . Therefore, the turn-on moment of the TRIAC device 202 is delayed, eg, later than time T ₁ . Similarly, if the resistance value R ₂₀₄ of the variable resistor decreases, the turn-on moment of the TRIAC device 202 is advanced, for example, earlier than the time T ₁ . Therefore, by adjusting the resistance R ₂₀₄ of the variable resistor 204 , the conduction moment of the TRIAC device 202 in each half cycle is adjusted accordingly, for example, the conduction moment is delayed or advanced. The TRIAC dimmer 104 may have other structures, and is not limited to the embodiments shown in FIG. 1B and FIG. 1C . In another embodiment, if the resistance R ₂₀₄ of the variable resistor 204 is changed, for example, the resistance R ₂₀₄ is adjusted by the user, the turn-off time of the TRIAC device 202 in each half cycle is adjusted. For illustration, in the following description, the TRIAC dimmer 104 adjusts the turn-on moment of the TRIAC device 202 . However, the present invention is not limited thereto, and the TRIAC dimmer 104 of the present invention is also suitable for adjusting the turn-off time of the TRIAC device 202 .

Returning to FIG. 1A and FIG. 1B, the brightness and color temperature controller 112 receives a conduction detection signal TD indicating the conduction state of the TRIAC device 202 (for example, a conduction angle between 0-180 degrees), and based on the conduction detection Signal TD to adjust the brightness of the light source (for example, the value of current I _LED1 or current I _LED2 ). The brightness and color temperature controller 112 generates a driving signal DRV according to the conduction detection signal TD. The driving signal DRV controls the control switch in the power converter 108 (for example, the control switch Q3 in FIG. The average current flowing through the LED light source (eg, current I _LED1 or current I _LED2 ). More specifically, in one embodiment, the brightness and color temperature controller 112 detects the conduction moment of the TRIAC device 202 in each cycle based on the conduction detection signal TD. If the resistance value R ₂₀₄ of the variable resistor 204 is increased (eg, by turning the knob of the TRIAC dimmer 104 ), the turn-on moment of the TRIAC device 202 is delayed in each cycle. Thus, the brightness and color temperature controller 112 controls the switch Q3 to reduce the average current flowing through the LED light source (eg, the first LED string 120 or the second LED string 130 ). Similarly, if the resistance R ₂₀₄ of the variable resistor 204 decreases, the brightness and color temperature controller 112 controls the switch Q3 to increase the average current flowing through the LED light source (eg, the first LED chain 120 or the second LED chain 130 ). For example, if as described above, if the brightness and color temperature controller 112 generates the first control signal CTR1 according to the switch monitoring signal TS to turn on the first control switch 122 and adjust the color temperature of the light source to the first color temperature value, the brightness and color temperature The controller 112 adjusts the average current I _LED1 flowing through the first LED light source 120 according to the operation of the TRIAC dimmer 104 . If the brightness and color temperature controller 112 generates the second control signal CTR2 according to the switch monitoring signal TS to turn on the second control switch 132 and adjust the color temperature of the light source to the second color temperature value, then the brightness and color temperature controller 112 according to the TRIAC dimmer 104 to adjust the average current I _LED2 flowing through the second LED light source 130 .

Advantageously, the brightness and color temperature controller 112 can not only adjust the color temperature of the light source (e.g., the first LED chain 120 and the second LED chain 130) according to the operation of the ON/OFF switch 102, but also can adjust the color temperature according to the TRIAC dimmer 104 at the same time. Adjust the brightness of the LED light source (for example, the first LED chain 120 and the second LED chain 130 ) without using additional special devices, which is simple, convenient and cost-saving. The operation of the brightness and color temperature controller 112 will be further described in conjunction with FIG. 3 .

FIG. 3 is a schematic circuit diagram of a light source driving circuit 300 according to an embodiment of the present invention. In FIG. 3 , the power supply V _IN and the TRIAC dimmer 104 are not shown for simplicity. The light source driving circuit 300 is powered by a power source V _IN (for example, 110/120V AC, 60Hz) via the ON/OFF switch 102 and the TRIAC dimmer 104 . The AC voltage V _TRIAC is converted to a rectified voltage V _REC via a filter 302 and a rectifier 106 (eg, a bridge rectifier composed of diodes D1 - D4 ). The power converter 108 receives the rectified voltage V _REC from the rectifier 106 and provides a regulated output current I _OUT to the light sources (eg, the first LED string 120 and the second LED string 130 ).

In the example of FIG. 3 , the power converter 108 includes a transformer 110 , a control switch Q3 , a diode D5 and a capacitor C8 . Transformer 110 includes primary winding 305 for receiving rectified voltage V _REC from rectifier 106, secondary winding 307 for providing output current I _OUT to first LED chain 120 and second LED chain 130, magnetic core 311 and for Auxiliary winding 309 that supplies voltage to brightness and color temperature controller 112 . The transformer 110 shown in FIG. 3 including three windings is for example and not limiting. In other embodiments, the transformer 110 may include other different numbers of windings. In the embodiment shown in FIG. 3 , the control switch Q3 coupled to the primary winding 305 is external to the brightness and color temperature controller 112 . In other embodiments, the control switch Q3 can also be integrated inside the brightness and color temperature controller 112 .

The brightness and color temperature controller 112 is coupled to the primary winding 305 and the auxiliary winding 309 of the transformer 110 . The brightness and color temperature controller 112 can be a flyback pulse width modulation (PWM) controller, which is used to generate a PWM signal to selectively turn on the control switch Q3 connected in series with the primary winding 305, and adjust the duty cycle of the PWM signal to adjust the output current I _OUT of the transformer 110 . By way of example but not limitation, the ports of the brightness and color temperature controller 112 include ports HV, CLK, PWM, VDD, GND, COMP, CS, FB, SW1 and SW2.

The brightness and color temperature controller 112 receives the conduction detection signal TD of the rectified voltage V _IN at the port HV and adjusts the average current (eg, current I _LED1 or current I _LED2 ) flowing through the LED light source according to the conduction detection signal TD. Specifically, the conduction detection signal TD may indicate the conduction state (eg, conduction angle between 0-180 degrees) of the TRIAC device 202 in the TRIAC dimmer 104 . The brightness and color temperature controller 112 can provide a reference signal REF corresponding to the conduction angle of the TRIAC dimmer 104 based on the conduction detection signal TD (as detailed in FIGS. A driving signal DRV is generated to adjust the average current (eg, current I _LED1 or current I _LED2 ) flowing through the LED light source.

Advantageously, the brightness of the light sources (e.g., first LED chain 120 and second LED chain 130) in the secondary circuit is adjusted by brightness and color temperature controller 112 in response to rotational operation of TRIAC dimmer 104 in the primary circuit is the target brightness value corresponding to the conduction angle of the TRIAC dimmer 104 (eg, 25%, 50%, 75%, 90%, 100%, etc.).

The brightness and color temperature controller 112 receives a switch monitoring signal TS indicating a conduction state (for example, an on or off state) of the ON/OFF switch 102 at a port CLK, and generates a first control signal CTR1( at port SW1 ) and a second control signal CTR2 (at port SW2 ) to control the first LED chain 120 and the second LED chain 130 , respectively. More specifically, in one embodiment, if the switch monitoring signal TS indicates that the ON/OFF switch 102 is turned on for the first time, the brightness and color temperature controller 112 generates the first control signal CTR1 to turn on the first control switch 122 and The second control signal CTR2 is generated to turn off the second control switch 132, so that the current I _LED1 flows through the first LED chain 120 and no current flows through the second LED chain 130; if the switch monitoring signal TS indicates that the ON/OFF switch 102 is off is turned on and turned on again within a predetermined period of time, the brightness and color temperature controller 112 generates a first control signal CTR1 to turn off the first control switch 122 and generates a second control signal CTR2 to turn on the second control switch 132, therefore, No current flows through the first LED chain 120 , and the current I _LED2 flows through the second LED chain 130 . Since the second LED chain 130 may have a different color temperature from the first LED chain 120, the brightness and color temperature controller 112 may adjust the color temperature of the light source according to the switch monitoring signal TS.

Port FB receives a current monitoring signal SEN indicating the current IS flowing through the secondary winding 307 from a voltage divider circuit ₍ not shown) coupled to the auxiliary winding 309 of the transformer 110 (for example, the current monitoring signal SEN may indicate the current IS flowing through the secondary winding 307). When the current _IS of 307 drops to 0). The port CS receives a monitoring signal LPSEN indicating the current _IP flowing through the primary winding 305 . The brightness and color temperature controller 112 receives the current monitoring signal SEN and the monitoring signal LPSEN, and generates a driving signal DRV at the port PWM to control the control switch Q3 to adjust the output current I _OUT of the power converter 108 . The brightness and color temperature controller 112 generates a driving signal DRV at the port PWM according to the current monitoring signal SEN and the monitoring signal LPSEN to control the conduction state (eg, on or off state) of the control switch Q3. For example, when the current monitoring signal SEN indicates that the current _IS flowing through the secondary winding 307 drops to 0, the driving signal DRV can switch the control switch Q3 from the off state to the on state. More specifically, the voltage of the current monitoring signal SEN can be compared with the voltage of a reference signal indicating the target current value _ITARGET flowing through the light source, and the voltage of the monitoring signal LPSEN can be compared with that of another reference signal indicating the target current value _ITARGET . The voltages are compared, and if any comparison result indicates that the instantaneous current value flowing through the light source is greater than the target current value I _TARGET , the brightness and color temperature controller 112 reduces the duty cycle of the driving signal DRV, and vice versa. In one embodiment, if the driving signal DRV is in the first state (for example, logic high level), the control switch Q3 is turned on, the current flows through the primary winding 305 , and the magnetic core 311 stores energy. If the driving signal DRV is in the second state (for example, logic low level), the control switch Q3 is turned off, and the diode D5 coupled to the secondary winding 307 is forward biased so that the energy stored in the magnetic core 311 can pass through the secondary Side winding 307 discharges to capacitor C8 and the light source. Therefore, the power of the light sources (for example, the first LED chain 120 and the second LED chain 130 ) can be adjusted according to the driving signal DRV.

Port VDD is coupled to auxiliary winding 309 . In one embodiment, an energy storage unit (eg, capacitor C5 ) coupled between the port VDD and ground provides power to the brightness and color temperature controller 112 when the ON/OFF switch 102 is open. Port COMP is coupled to ground (port GND) through a capacitor to provide an error signal.

Advantageously, in response to the OFF operation of the ON/OFF switch 102 in the primary side circuit, after the ON/OFF switch 102 is turned on again within a predetermined period of time after the OFF operation of the ON/OFF switch 102, in the secondary side circuit The color temperature of the light sources (for example, the first LED chain 120 and the second LED chain 130) is adjusted by the brightness and color temperature controller 112 to a target color temperature value (for example, the first color temperature value or the second color temperature value).

FIG. 4 is a schematic structural diagram of the brightness and color temperature controller 112 in FIG. 3 . FIG. 4 will be described in conjunction with FIG. 3 . In the example of FIG. 4 , the brightness and color temperature controller 112 is divided into a brightness control module in the upper part and a color temperature control module in the lower part.

The working principle of the brightness control module is as follows:

The brightness control module includes a signal generator 410 , a TRIAC monitor 432 and a driver 430 . The signal generator 410 generates a monitoring signal (eg, a square wave signal 412 ). The average voltage of the monitor signal is proportional to the average current I _OUT (eg, current I _LED1 or I _LED2 ) flowing through the LED light source (eg, the first LED string 120 or the second LED string 130 ). The TRIAC monitor 432 generates a reference signal REF according to the conduction detection signal TD. The reference signal REF indicates a target current value (eg, target current value I _TARGET ) of the average current flowing through the LED light source (eg, the first LED string 120 or the second LED string 130 ). Accordingly, the driver 430 generates the driving signal DRV based on the square wave signal 412 and the reference signal REF. The signal generator 410, the driver 430 and the transformer 110 form a negative feedback loop. The negative feedback loop keeps the average voltage of the square wave signal 412 equal to the reference signal REF, thereby keeping the average current I _OUT flowing through the LED light source (eg, the first LED string 120 or the second LED string 130 ) equal to the target current value I _TARGET . Please note that the conduction angle of the TRIAC dimmer 104 can change with the user's rotation operation, so the reference signal REF also changes accordingly. In this way, the adjustment of the brightness of the LED light source is realized.

The signal generator 410 includes an acquisition circuit 402 , a state detector 404 and a multiplexer 408 . The acquisition circuit 402 is connected to the port CS to receive the monitoring signal LPSEN indicating the current flowing through the primary winding 305 . The acquisition circuit 402 samples and holds the monitoring signal LPSEN and generates a peak signal V _PK proportional to the peak value of the current flowing through the primary winding 305 . In one embodiment, multiplexer 408 includes a switch having a first port, a second port, and a third port. The first port of the multiplexer 408 is connected to the output terminal of the acquisition circuit 402 for receiving the peak signal V _PK . The second port of the multiplexer 408 is connected to the reference ground GND for receiving the preset voltage signal V _PRE (for example, V _PRE is zero volts). The third port of the multiplexer 408 is connected to the input terminal of the driver 430 for providing the square wave signal 412 . In another embodiment, the second port of the multiplexer 408 may also be connected to other signal generators to receive a preset constant reference voltage.

The state detector 404 is connected to the port FB to receive the current monitoring signal SEN. The state detector 404 determines whether the transformer 110 is working in a preset state according to the current monitoring signal SEN, and generates a switch control signal 406 to control the multiplexer 408 . More specifically, in one embodiment, when the current monitoring signal SEN has a first voltage value indicating that the transformer 110 is operating in a preset state, the switch control signal 406 has a first state (eg, high level). At this time, the first port and the third port of the multiplexer 408 are turned on. Thus, the square wave signal 412 is equal to the peak signal V _PK . When the current monitoring signal SEN has the second voltage value indicating that the transformer 110 is not working in the preset state, the switch control signal 406 has the second state (eg, low level). At this time, the second port and the third port of the multiplexer 408 are turned on. Thus, the square wave signal 412 is equal to the preset voltage signal V _PRE .

Advantageously, the TRIAC monitor 432 is capable of adjusting the reference signal REF according to the TRIAC dimmer 104 . More specifically, in one embodiment, TRIAC monitor 432 increases reference Signal REF. As a result, the average current flowing through the LED light sources (eg, the first LED string 120 or the second LED string 130 ) increases. Similarly, if the conduction detection signal TD indicates that the conduction moment of the TRIAC device 202 in each cycle is delayed (ie, the conduction angle decreases), the TRIAC monitor 432 decreases the reference signal REF. As a result, the average current flowing through the LED light source (eg, the first LED string 120 or the second LED string 130 ) is reduced. The brightness control module may have other structures, and is not limited to the embodiment shown in FIG. 4 .

FIG. 5 is a schematic structural diagram of the TRIAC monitor 432 in FIG. 4 according to an embodiment of the present invention. FIG. 5 will be described in conjunction with FIG. 4 . In the example of FIG. 5 , TRIAC monitor 432 includes voltage divider 502 , comparator 506 and filter 510 . In one embodiment, the voltage divider 502 includes a resistor R7 and a resistor R8 coupled in series. The voltage divider 502 receives the conduction detection signal TD and provides a divided voltage signal 504 indicating the rectified voltage V _IN . The comparator 506 compares the divided voltage signal 504 with the threshold voltage V _TH and generates a square wave signal 508 according to the comparison result. The filter 510 filters the square wave signal 508 to generate a reference signal REF.

More specifically, in one embodiment, during the on-time T _{TRI_ON} from time T ₁ to time T ₂ , the divided voltage signal 504 is greater than the threshold voltage V _TH (eg, zero volts), and the square wave signal 508 is switched to high level. During the off-time T _{TRI_OFF} from time T ₂ to time T ₃ , the divided voltage signal 504 is lower than the threshold voltage V _TH , and the square wave signal 508 is switched to a low level. When the conduction moment of the TRIAC device 202 changes, the average voltage of the square wave signal 508 changes accordingly. Filter 510 filters square wave signal 508 to provide a reference signal REF that is proportional to the average voltage of square wave signal 508 . Therefore, the average current flowing through the LED light source (for example, the first LED chain 120 or the second LED chain 130) can be adjusted by adjusting the reference signal REF, thereby realizing the adjustment of the LED light source (for example, the first LED chain 130) according to the TRIAC dimmer 104 chain 120 or second LED chain 130) dimming control. The TRIAC monitor 432 may have other structures and is not limited to the embodiment of FIG. 5 .

Driver 430 includes operational amplifier 414 , sawtooth generator 420 , comparator 426 and buffer 428 . In one embodiment, the operational amplifier 414 includes an operational transconductance amplifier (Operational Transconductance Amplifier, OTA) 418 and a capacitor 416 . The positive input terminal of the operational transconductance amplifier 418 receives the square wave signal 412 , and the negative input terminal receives the reference signal REF. Wherein, the reference signal REF represents the target current value I _TARGET of the output current I _LED1 or I _LED2 . The operational transconductance amplifier 418 generates a current I ₄₁₈ at the output terminal to charge or discharge the capacitor 416 according to the difference between the square wave signal 412 and the reference signal REF, thereby generating an error signal 422 . Since the capacitor 416 filters the ripple on the error signal 422 , the error signal 422 is determined by the difference between the average voltage V _{SQ_AVG} of the square wave signal 412 and the reference signal REF. In another embodiment, the capacitor 416 is outside the brightness and color temperature controller 112 and connected to the operational transconductance amplifier 418 through a port of the controller.

The sawtooth generator 420 generates a sawtooth signal SAW. The comparator 426 compares the error signal 422 with the sawtooth signal SAW and generates a comparison signal. The buffer 428 receives the comparison signal and generates a driving signal DRV (eg, a PWM signal). In the embodiment of FIG. 4 , if the average voltage V _{SQ_AVG} of the square wave signal 412 increases, the error signal 422 increases accordingly, and the sawtooth signal SAW needs more time to increase to the error signal 422 . Thus, the duty cycle of the driving signal DRV decreases, thereby reducing the average current of the output current I _LED1 or I _LED2 until the average voltage V _{SQ_AVG} of the square wave signal 412 decreases to the reference signal REF. Similarly, if the average voltage V _{SQ_AVG} of the square wave signal 412 decreases, the duty cycle of the drive signal DRV will increase, thereby increasing the average current of the output current I _LED1 or I _LED2 until the average voltage V _{SQ_AVG} of the square wave signal 412 Increase to reference signal REF. In this way, the average current of the output current I _LED1 or I _LED2 can be adjusted to be equal to the target current value I _TARGET , that is, the brightness control of the light source (eg, the first LED chain 120 and the second LED chain 130 ) can be realized.

In addition, the working principle of the color temperature control module is as follows:

FIG. 6 is a schematic structural diagram of the color temperature control module in FIG. 4 . Referring to FIG. 4 and FIG. 6 , the color temperature control module includes a decision unit 434 , a NOT gate 436 , a start-up and low voltage lockout (UVL) circuit 438 , and a color temperature control unit 440 .

The activation and low voltage lockout (UVL) circuit 438 is connected to the port VDD, and is used to selectively activate one or more components inside the brightness and color temperature controller 112 according to different power conditions.

In one embodiment, the enable and low voltage lockout circuit 438 activates all components in the brightness and color temperature controller 112 if the voltage on the port VDD is higher than the first preset voltage. When the ON/OFF switch 102 is turned off, if the voltage on the terminal VDD is lower than the second predetermined voltage, the start-up and low-voltage lockout circuit 438 will turn off some components in the brightness and color temperature controller 112 to save power. If the voltage on the port VDD is lower than the third preset voltage, the startup and low voltage lockout circuit 438 will shut down all components. In one embodiment, the first preset voltage is higher than the second preset voltage, and the second preset voltage is higher than the third preset voltage.

The determination unit 434 detects the power state of the brightness and color temperature controller 112 and generates a first determination signal VDD_L and a second determination signal VDD_H based on the power state of the brightness and color temperature controller 112 . The brightness and color temperature controller 112 adjusts the color temperature of the light source based on the first determination signal VDD_L, the second determination signal VDD_H and the switch monitoring signal TS. For example, if the voltage at the port VDD of the brightness and color temperature controller 112 is less than the reset threshold voltage (for example, 4V), the first decision signal VDD_L has a first state (for example, a logic high level); if the brightness and color temperature control If the voltage at the port VDD of the controller 112 is greater than the reset threshold voltage (for example, 4V), the first determination signal VDD_L has a second state (for example, a logic low level); if the voltage at the port VDD of the brightness and color temperature controller 112 If the voltage is less than the enable threshold voltage (for example, 10V), the second determination signal VDD_H has a first state (for example, logic low level); if the voltage at the port VDD of the brightness and color temperature controller 112 is greater than the enable threshold voltage ( For example, 10V), the second determination signal VDD_H has a second state (for example, logic high level).

The color temperature control unit 440 is used to generate a first control signal CTR1 and a second control signal CTR2 according to the switch monitoring signal TS, the first determination signal VDD_L and the second determination signal VDD_H to control the first LED chain 120 and the second LED chain 130 respectively. In one embodiment, the color temperature control unit 440 includes a timer 602 , a first D flip-flop 604 , a second D flip-flop 606 , a first AND gate 608 and a second AND gate 610 . The timer 602 receives the switch monitoring signal TS and starts timing when the switch monitoring signal TS has a falling edge. The timer 602 also generates a pulse signal TS_DE after a predefined time interval Δt of each falling edge of the switch monitoring signal TS. The pulse signal TS_DE is coupled to the input port CLK of the first D flip-flop 604 , and the switch monitoring signal TS is coupled to the input port CLK of the second D flip-flop 606 . The input port D1 of the first D flip-flop 604 is coupled to its output port And the output port Q1 of the first D flip-flop 604 is coupled to the input port D2 of the second D flip-flop 606 .

The input ports R of the first D flip-flop 604 and the second D flip-flop 606 are both coupled to the output port of the NOT gate 436 , and the input port of the NOT gate 436 is coupled to the decision unit 434 . If the voltage at the terminal VDD of the brightness and color temperature controller 112 is less than the reset threshold voltage (for example, 4V), the first decision signal VDD_L is logic high level, and the first D flip-flop 604 and the second D flip-flop 606 are both It is reset through the NOT gate 436, therefore, the output port Q1 of the first D flip-flop 604 and the output port Q2 of the second D flip-flop 606 are both reset to a logic low level, and the output port Q2 of the first D flip-flop 604 output port and the output port of the second D flip-flop 606 are reset to a logic high level.

Both the second determination signal VDD_H and the output port _Q2 of the second D flip-flop 606 are coupled to the first AND gate 608, and the first AND gate 608 generates the first control signal CTR1 to control the first control switch 122 and flow through the first LED The current I _LED1 of the chain 120 . Both the second determination signal VDD_H and the output port Q2 of the second D flip-flop 606 are coupled to the second AND gate 610, and the second AND gate 610 generates the second control signal CTR2 to control the second control switch 132 and flow through the second LED chain 130 current I _LED2 . In this way, the brightness and color temperature controller 112 can adjust the color temperature of the light source in response to the OFF operation of the ON/OFF switch 102 .

FIG. 7 is a signal waveform diagram of a light source driving circuit including the color temperature control module shown in FIG. 6 . Fig. 7 shows the switch monitoring signal TS, the pulse signal TS_DE, the first judgment signal VDD_L, the second judgment signal VDD_H, the voltage at the input port D1, the voltage at the output port Q1, the voltage at the output port Q2, the first control Signal waveforms of the signal CTR1 and the second control signal CTR2. FIG. 7 will be described in conjunction with FIGS. 3 and 6 .

At time t0, the ON/OFF switch 102 is turned on. At time t1, the switch monitoring signal TS changes from the first state (for example, logic low level) to the second state (for example, logic high level), and the voltage at the port VDD increases to the reset threshold voltage (for example, 4V ) and the first determination signal VDD_L changes from a first state (eg, logic high level) to a second state (eg, logic low level). At time t2, the voltage at the port VDD increases to the enable threshold voltage (for example, 10V) and the second decision signal VDD_H changes from the first state (for example, logic low level) to the second state (for example, logic high level flat). During the time interval from time t0 to time t2, the output port Q1 of the first D flip-flop 604 and the output port Q2 of the second D flip-flop 606 are logic low. Since the second determination signal VDD_H received by the first AND gate 608 and the second AND gate 610 is logic low level, both the first control signal CTR1 and the second control signal CTR2 are also logic low level. After time t2, since the second decision signal VDD_H changes to a logic high level, the first control signal CTR1 also changes to a logic high level, therefore, the first control switch 122 is turned on and the current I _LED1 starts to flow through the first LED Chain 120. At time t3, the ON/OFF switch 102 is turned off, and the voltage at the terminal VDD of the brightness and color temperature controller 112 starts to drop. As mentioned above, once the switch monitor signal TS has a falling edge, the pulse signal TS_DE may be generated after a predefined time interval Δt. At time t4, in response to the rising edge of the pulse signal TS_DE, the input port D1 of the first D flip-flop 604 changes from a logic high level to a logic low level, and the output port Q1 of the first D flip-flop 604 changes from a logic low level level changes to a logic high level. At time t5, the voltage at the port VDD drops to the enable threshold voltage (for example, 10V), and the second decision signal VDD_H changes from the second state (for example, logic high level) to the first state (for example, logic low level) flat). Therefore, since the second determination signal VDD_H received by the first AND gate 608 and the second AND gate 610 is logic low level, both the first control signal CTR1 and the second control signal CTR2 are also logic low level.

At time t6, the switch monitoring signal TS has a rising edge, indicating that the ON/OFF switch 102 is turned on again. The time interval from time t3 to time t6 is less than a predetermined (regulation) time interval (for example, t6-t3<3 seconds), so that the voltage at the port VDD remains above the reset threshold voltage (for example, 4V) and the first determination signal VDD_L remains logic low. In response to the rising edge of the switch monitoring signal TS, the output port Q2 of the second D flip-flop 606 changes from a logic low level to a logic high level, and its output port change from logic high to logic low. Similar to the time interval from time t1 to time t2, and the time interval from time t6 to time t7, both the first control signal CTR1 and the second control signal CTR2 are logic low level. After time t7, the voltage at the port VDD increases above the enabling threshold voltage, the second determination signal VDD_H changes to a logic high level, and the second control signal CTR2 also changes to a logic high level, and the second control switch 132 is switched on and the current I _LED2 starts to flow through the second LED chain 130 . Then, the ON/OFF switch 102 is turned off again, and the voltage at the port VDD drops to the enable threshold voltage (eg, 10V) at time t8. The signal waveform in the time interval from time t8 to time t10 is similar to the signal waveform in the time interval from time t0 to time t5. At time t9, the first control switch 122 is turned on and the current I _LED1 starts to flow through the first LED chain 120 .

Therefore, the brightness and color temperature controller 112 alternately turns on the first control switch 122 and the second control switch 132 in response to the OFF operation of the ON/OFF switch 102, since the second LED chain 130 may have a different color than the first LED chain 120 Therefore, the brightness and color temperature controller 112 can adjust the color temperature of the light source in response to the OFF operation of the ON/OFF switch 102 .

FIG. 8 is a signal waveform diagram of a light source driving circuit including the color temperature control module shown in FIG. 6 according to another embodiment of the present invention. Fig. 8 shows the switch monitoring signal TS, the pulse signal TS_DE, the first determination signal VDD_L, the second determination signal VDD_H, the voltage at the input port D1, the voltage at the output port Q1, the voltage at the output port Q2, the first control Signal waveforms of the signal CTR1 and the second control signal CTR2. FIG. 8 will be described in conjunction with FIG. 3 , FIG. 6 and FIG. 7 .

The waveform in the time interval from the time t0 to the time t6' is similar to the waveform in the time interval from the time t0 to the time t6 in Fig. 7 . At time t7', the ON/OFF switch 102 is turned on again. The time interval from time t3 to time t7' is greater than a predetermined time interval (for example, t7'-t3>3 seconds). Therefore, at time t6', the voltage at the port VDD drops to the reset threshold voltage (for example, 4V), and the first determination signal VDD_L changes from a logic low level to a logic high level, and both the output port Q1 and the output port Q2 is reset to logic low. Since the second determination signal VDD_H received by the first AND gate 608 and the second AND gate 610 is logic low level, the first control signal CTR1 and the second control signal CTR2 are both logic low level.

At time t8', the switch monitoring signal TS changes from the first state (for example, logic low level) to the second state (for example, logic high level), and the voltage at the port VDD increases to the reset threshold voltage (for example, 4V), and the first decision signal VDD_L changes from a first state (eg, logic high level) to a second state (eg, logic low level). At time t9', the voltage at the port VDD increases to the enable threshold voltage (for example, 10V), and the second decision signal VDD_H changes from the first state (for example, logic low level) to the second state (for example, logic high level). The signal waveform in the time interval from time t7' to time t9' is similar to the signal waveform in the time interval from time t0 to time t2. After time t9', the voltage at the port VDD increases above the enable threshold voltage, the second determination signal VDD_H changes to a logic high level, and the first control signal CTR1 also changes to a logic high level. Then, the first control switch 122 is turned on and the current I _LED1 starts flowing through the first LED chain 120 .

As shown in FIG. 7, if the switch monitoring signal TS indicates that the time interval between the OFF operation of the ON/OFF switch 102 and the next ON operation is less than a predetermined time interval (for example, 3 seconds), the brightness and color temperature controller 112 The color temperature of the light source (eg, the first LED string 120 and the second LED string 130 ) is changed from the first color temperature value to the second color temperature value in response to the next ON operation of the ON/OFF switch 102 . More specifically, in the example of FIG. 7, during a first time interval (for example, the time interval from time t2 to time t5), the first control signal CTR1 is at a logic high level, and the first LED chain 120 is turned on. , the second LED chain 130 is disconnected, so that the color temperature of the light source is adjusted to the first color temperature value; The second control signal CTR2 is logic high level, the first LED chain 120 is turned off, and the second LED chain 130 is turned on, so that the color temperature of the light source is adjusted to the second color temperature value. Thus, the brightness and color temperature controller 112 changes the color temperature of the light source from the color temperature of the first LED chain 120 to the color temperature of the second LED chain 130 by alternately turning on the first control switch 122 and the second control switch 132 . However, as shown in FIG. 8, if the switch monitoring signal TS indicates that the time interval between the OFF operation of the ON/OFF switch 102 and the next ON operation is greater than a predetermined time interval (for example, 3 seconds), the brightness and color temperature control The controller 112 resets the color temperature of the light source to a preset color temperature value in response to the next ON operation of the ON/OFF switch 102. In the example of FIG. 8 , the preset color temperature value may be the color temperature value of the first LED chain 120 , for example, the color temperature value set by factory; the preset color temperature value is not limited to the color temperature value shown in the example of FIG. 8 .

FIG. 9 shows a flowchart 900 of a method for controlling the brightness and color temperature of a light source according to an embodiment of the present invention. FIG. 9 will be described in conjunction with FIGS. 1A-8 . The specific steps covered in FIG. 9 are examples only, ie, the invention is applicable to steps that perform various other steps or modifications to the steps represented in FIG. 9 .

In step 902, a driver circuit (eg, light source driver circuit 100 or 300) receives power from a power source and is supplied by a power converter (eg, power converter 108) to the light sources (eg, first LED chain 120 and second LED chain 130) Provides regulated electrical energy.

In step 904, the reference signal indicating the target current value flowing through the light source is adjusted according to the conduction detection signal, so as to adjust the average current flowing through the light source accordingly, thereby adjusting the brightness of the light source. In one embodiment, the conduction detection signal TD indicative of the conduction state of the TRIAC dimmer 104 coupled between the power supply and the power converter is received by the brightness and color temperature controller 112 and adjusted based on the conduction detection signal TD. A reference signal indicating the target current value flowing through the light source. Specifically, the conduction detection signal TD indicates the conduction state (eg, conduction angle between 0-180 degrees) of the TRIAC device 202 in the TRIAC dimmer 104 . The brightness and color temperature controller 112 can provide a reference signal REF corresponding to the conduction angle of the TRIAC dimmer 104 according to the conduction detection signal TD (as described in detail in FIGS. 4 and 5 above), and according to the reference signal REF at The drive signal DRV is generated at the port PWM to adjust the average current (for example, the current I _LED1 or the current I _LED2 ) flowing through the LED light source.

In step 906, a switch monitor signal is received (eg, switch monitor signal TS received by brightness and color temperature controller 112) indicative of an ON/OFF switch (eg, ON/OFF switch) coupled between the power supply and the power converter. OFF switch 102) operation.

In step 908, the color temperature of the light source is adjusted based on the switch monitoring signal TS. For example, during a first time interval (eg, the time interval from time t2 to time t5 in FIG. 7 ), brightness and color temperature controller 112 may generate a first control signal CTR1 to turn on the first LED chain 120, and generate a second control signal CTR2 to disconnect the second LED chain 130 with a second color temperature value, so that the color temperature of the light source is adjusted to the first color temperature value; at a second time different from the first time interval During the interval (for example, the time interval from time t7 to time t8 in FIG. 7 ), the brightness and color temperature controller 112 may generate a first control signal CTR1 to disconnect the first LED chain 120, and generate a second control signal CTR2 to The second LED chain 130 is turned on, so that the color temperature of the light source is adjusted to the second color temperature value.

In this way, the brightness and color temperature controller 112 can not only adjust the color temperature of the light source (e.g., the first LED chain 120 and the second LED chain 130) according to the operation of the ON/OFF switch 102, but also simultaneously according to the TRIAC dimmer 104 Adjust the brightness of the LED light source (for example, the first LED chain 120 and the second LED chain 130 ) without using additional special devices, which is simple, convenient and cost-saving.

The above description is based on an example of an embodiment of an LED chain. However, embodiments according to the present invention may also be applied to other types of light sources. In other words, the embodiments of the present invention are not limited to LED light sources, and are also applicable to other types of light sources.

The words and expressions used herein are for the purpose of description and not limitation, and the use of these words and expressions does not exclude from the scope of the invention any equivalent (or partial equivalent) of the characteristics shown and described herein. Various modifications are possible within the scope of the claims. Other modifications, variations and alternatives are also possible. Accordingly, the claims are intended to cover all such equivalents.

Claims (9)

1. A light source drive circuit for adjusting the brightness and color temperature of a light source, the light source comprising a first light emitting element with a first color temperature value and a second light emitting element with a second color temperature value, characterized in that the light source The drive circuit includes: a power converter coupled between a power source and the light source for receiving power from the power source and providing conditioned power to the light source; and a brightness and color temperature controller coupled to the power converter for receiving a conduction detection signal indicative of a conduction state of a triac dimmer coupled between the power source and the power converter, and adjusting the brightness of the light source based on the conduction detection signal, wherein the brightness and color temperature controller is further configured to receive a switch indicating operation of an on/off switch coupled to the triac dimmer monitoring a signal, and adjusting the color temperature of the light source based on the switch monitoring signal, Wherein, the brightness and color temperature controllers include: a judging unit configured to detect the power state of the brightness and color temperature controller and generate a first judgment signal and a second judgment signal based on the power state of the brightness and color temperature controller; and A color temperature control unit, configured to generate a first control signal and a second control signal according to the first determination signal, the second determination signal and the switch monitoring signal, wherein the first control signal selectively turning on a first control switch coupled between the brightness and color temperature controller and the first light emitting element to adjust the color temperature of the light source to the first color temperature value, the second control A signal selectively turns on a second control switch coupled between the brightness and color temperature controller and the second light emitting element to cause the color temperature of the light source to be adjusted to the second color temperature value. 2. The light source driving circuit according to claim 1, wherein the brightness and color temperature controller further comprises: a signal generator for generating a monitoring signal proportional to the average current flowing through the light source; a triac for receiving the conduction detection signal and generating a reference signal indicative of a target value of an average current flowing through the light source based on the conduction detection signal; and a driver, coupled to the signal generator and the triac monitor, for generating a driving signal according to the monitoring signal and the reference signal, so as to control the power converter to provide the regulated Electrical energy is supplied to the light source. 3. The light source driving circuit according to claim 2, wherein the signal generator, the driver and the transformer in the power converter form a negative feedback loop, and the negative feedback loop keeps flowing through the The average current of the light source is equal to the target value. 4. The light source driving circuit according to claim 2, wherein the conduction detection signal indicates the conduction angle of the triac dimmer, and if the conduction detection signal indicates the conduction angle of the triac dimmer, As the conduction angle increases, the triac increases the reference signal and the driver adjusts the drive signal to increase the average current through the light source, and if the conduction The detection signal indicates that the conduction angle is reduced, the triac reduces the reference signal and the driver adjusts the drive signal to reduce the average current through the light source. 5. The light source driving circuit according to claim 1, wherein the color temperature control unit comprises: a timer, configured to receive the switch monitoring signal, the timer starts counting when the switch monitoring signal has a falling edge, and generates a pulse signal after a predefined time interval of the falling edge; The first D flip-flop is used to receive the pulse signal; and a second D flip-flop, coupled to the first D flip-flop, for receiving the switch monitoring signal; Wherein the first control signal and the second control signal are generated based on the output signal of the second D flip-flop. 6. The light source driving circuit according to claim 1, wherein if the switch monitoring signal indicates that the time interval between the off operation of the on/off switch and the next on operation is less than a predetermined time interval, The brightness and color temperature controller then adjusts the color temperature of the light source from a first color temperature value to a second color temperature value in response to the next on operation of the on/off switch. 7. The light source driving circuit according to claim 1, wherein if the switch monitoring signal indicates that the time interval between the off operation of the on/off switch and the next on operation is greater than a predetermined time interval, The brightness and color temperature controller then resets the color temperature of the light source to a preset color temperature value in response to the next ON operation of the on/off switch. 8. The light source driving circuit according to claim 1, wherein the light source driving circuit further comprises a rectifier, the power converter comprises a transformer, and the transformer comprises a primary winding, a secondary winding and an auxiliary winding, the The primary winding is coupled to the rectifier and receives power from the power supply through the rectifier, the secondary winding is used to provide the regulated power to the light source, and the auxiliary winding is used to supply the brightness and a color temperature controller, the on/off switch and the triac dimmer are coupled between the power supply and the rectifier. 9. The light source driving circuit according to claim 1, wherein the brightness and color temperature controller is configured to receive a current monitoring signal indicating the current value flowing through the light source, and control the current monitoring signal provided to the The adjusted electrical power of the light source.