CN107995732B

CN107995732B - Combined circuit and control circuit

Info

Publication number: CN107995732B
Application number: CN201711268754.5A
Authority: CN
Inventors: 张平伟; 杨巍巍
Original assignee: Opple Lighting Co Ltd
Current assignee: Opple Lighting Co Ltd
Priority date: 2017-12-05
Filing date: 2017-12-05
Publication date: 2020-03-31
Anticipated expiration: 2037-12-05
Also published as: CN107995732A

Abstract

The invention provides a combined circuit and a control circuit, wherein the combined circuit is applied to an LED drive circuit and comprises a detection module and a drive and logic conversion module connected with the detection module. The detection module detects the state of the external switch, generates a detection signal according to the detected state of the external switch, and sends the detection signal to the driving and logic conversion module. The driving and logic conversion module receives the detection signal from the detection module, generates a driving signal according to the detection signal, and drives the working state of a discharging module for discharging the output electrolytic capacitor of the LED driving circuit by using the state of the driving signal. Therefore, the detection module and the driving and logic conversion module are cooperatively used in the embodiment of the invention, and the driving and discharging module discharges the output electrolytic capacitor of the LED driving circuit, so that the LED light source does not flicker when emitting light due to residual energy on the output electrolytic capacitor.

Description

Combined circuit and control circuit

Technical Field

The present invention relates to the field of lighting technologies, and in particular, to a combination circuit and a control circuit.

Background

Because the LED has the advantages of energy conservation, environmental protection, high efficiency, safety and the like, the LED is widely applied to landscapes, street lamps and electronic product backlight lamps. With the wide application of LEDs, there is an increasing demand for products that switch color temperature or brightness of LEDs by using switches in the market, but in the actual use process of products that switch color temperature or brightness of LEDs by using switches, especially for high power factor LED products, there is a problem of flickering of LED lamps when the color temperature or brightness of LEDs is switched by using switches, thereby causing poor use experience for users using LED products.

For example, when the color temperature of the LED is switched by using the circuit shown in fig. 1, the LED may flicker. First, the working principle of the circuit is explained, assuming that the LED product defaults to the initial white LED (WLED-representing white LED in fig. 1) being bright. When the circuit is powered on for the first time, DRV _ W (where DRV is driver, and DRV _ W refers to a driving signal input to the white LED) is at a high level, DRV _ Y (refers to a driving signal input to the yellow LED) is at a low level, the switching tube (for example, a MOS tube shown in fig. 1) Q1 is turned on, the switching tube Q2 is turned off, and the white LED is turned on. When an external switch (not shown in fig. 1) is switched, the circuit detects a switch switching signal, DRV _ W is at a low level, DWR _ Y is at a high level, the switching tube Q1 is turned off, the switching tube Q2 is turned on, and a yellow LED (YLED-indicating yellow LED in fig. 1) is turned on. Of course, the principle can also be applied to LED products with brightness switched on and off.

In the prior art, the output electrolytic capacity of an LED driving circuit is large, and particularly, in single-stage PFC driving, the output of the LED driving circuit usually needs a large electrolytic capacitor to smooth the power frequency ripple of the output current. Therefore, when the color temperature of the LED is switched by the switch, the LED lamp flickers. Specifically, assume that the white LED is currently on, Q1 is on, and Q2 is off. The switch is turned off, and both Q1 and Q2 are turned off; the switch is closed, Q1 is off, and Q2 is on. At the moment of switch disconnection, because Q1 and Q2 are both cut off, the output electrolytic capacity is large, the quick discharge circuit of the output electrolytic capacitor without low impedance can only discharge through the output load resistor R1, the resistor R1 is usually large in resistance (the resistance is more than dozens of K ohms), the discharge time is long, if the switch is rapidly closed, Q1 is cut off, Q2 is conducted, when the drive does not start working, the residual energy on the output electrolytic capacitor can be released through the yellow LED, and the situation that the yellow LED flickers when the switch is rapidly switched can visually occur. Similarly, in an LED product with the switch for switching the LED brightness, the situation that the LED flickers visually appears when the switch is switched quickly also occurs.

Disclosure of Invention

In view of the above, the present invention has been developed to provide a combination circuit and a control circuit that overcome or at least partially solve the above-mentioned problems.

According to an aspect of the present invention, there is provided a combination circuit applied to an LED driving circuit, including: a detection module and a drive and logic conversion module connected with the detection module, wherein,

the detection module detects the state of the external switch, generates a detection signal according to the detected state of the external switch and sends the detection signal to the driving and logic conversion module;

and the driving and logic conversion module receives the detection signal from the detection module, generates a driving signal according to the detection signal, and drives the working state of a discharging module for discharging the output electrolytic capacitor of the LED driving circuit by using the state of the driving signal.

Optionally, if the external switch is off, the detection module generates a low level detection signal according to the external switch, the driving and logic conversion module generates a high level driving signal according to the low level detection signal, and drives the discharge module to operate, so that the discharge module discharges the output electrolytic capacitor of the LED driving circuit;

if the external switch is closed, the detection signal generated by the detection module according to the external switch is high level, the driving signal generated by the driving and logic conversion module according to the high level detection signal is low level signal, and the discharging module does not work.

Optionally, the detection module includes a first resistor, a capacitor, a diode, and an auxiliary winding of the power inductor, the first resistor is connected in parallel with the capacitor, and the diode and the auxiliary winding of the power inductor are connected in series and then connected in parallel with the capacitor;

if the external switch is closed, the voltage of the auxiliary winding of the power inductor is a high-frequency pulsating alternating-current square wave, and the voltage on the auxiliary winding of the power inductor is rectified and filtered by a diode and a capacitor device to generate a high-level detection signal; if the external switch is off, the diode is cut off and generates a low-level detection signal.

Optionally, the driving and logic converting module includes a voltage regulator diode and an MOS transistor, wherein one end of the voltage regulator diode is connected to the capacitor device, and the other end of the voltage regulator diode is connected to a gate of the MOS transistor;

if the detection signal generated by the detection module is at a low level, the voltage stabilizing diode is cut off, the MOS tube is cut off, and a high-level driving signal is generated and sent to the discharge module, and the electrolytic capacitor is output to be discharged through the discharge module;

if the detection signal generated by the detection module is at a high level, the voltage stabilizing diode is conducted and broken down, the MOS tube is driven to be conducted, a low-level driving signal is generated and sent to the discharge module, and the discharge module does not work.

According to another aspect of the present invention, there is also provided a control circuit applied to an LED driving circuit, including a switch module, a discharge module and the combination circuit of any of the above embodiments, wherein,

the switch module is connected with the at least two light sources, receives a switch switching signal from an external switch, and switches the color temperature and/or the brightness of the at least two light sources according to the switch switching signal;

and the discharging module is respectively connected with the change-over switch module and the driving and logic conversion module in the combined circuit, receives the driving signal output by the driving and logic conversion module, drives the self state by using the state of the driving signal, and discharges the output electrolytic capacitor of the LED driving circuit when the self state is the working state, so that the output electrolytic capacitor does not discharge through the current light-emitting source after the change-over switch module switches the color temperature and/or the brightness of at least two light sources.

Optionally, the control circuit is used for controlling or eliminating the flicker of the light source when the LED driving circuit switches the color temperature and/or the brightness of the light source by using the switch.

Optionally, the condition that the external switch generates the switch switching signal includes: if the external switch is in a closed state, a switch switching signal is generated when the external switch is opened and then closed.

Optionally, the discharge module comprises a second resistor and a triode, one end of the second resistor is connected with a collector of the triode, the other end of the second resistor is connected with one end of the output electrolytic capacitor, and the other end of the output electrolytic capacitor is connected with an emitter of the triode;

if the external switch state is off, the detection module of the combined circuit generates a low level according to the detection signal generated by the switch state, the driving and logic conversion module generates a high level signal according to the low level detection signal, drives the triode to be conducted, and the output capacitor discharges through the second resistor and the triode.

Optionally, the at least two light sources include light sources of at least two colors, and the color of each light source is different.

Optionally, the number of each of the at least two light sources is different.

Optionally, the at least two light sources include light sources of at least two colors, and each light source has different colors and numbers.

Optionally, the control circuit further comprises:

and the linear voltage stabilizing source is connected with the detection module of the combined circuit, receives the detection signal of the detection module and provides stable voltage for the driving and logic conversion module according to the detection signal.

The combined circuit in the embodiment of the invention is applied to an LED drive circuit, and comprises a detection module and a drive and logic conversion module connected with the detection module. The detection module detects the state of the external switch, generates a detection signal according to the detected state of the external switch, and sends the detection signal to the driving and logic conversion module. The driving and logic conversion module receives the detection signal from the detection module, generates a driving signal according to the detection signal, and drives the working state of a discharging module for discharging the output electrolytic capacitor of the LED driving circuit by using the state of the driving signal. Therefore, the detection module and the driving and logic conversion module are arranged on the LED driving circuit, so that the two modules cooperate with each other to drive the working state of the discharge module, the discharge module discharges the output electrolytic capacitor of the LED driving circuit, and the LED light source cannot flicker when emitting light due to residual energy on the output electrolytic capacitor. For example, the LED light source does not have visual stroboflash in the process of switching the color temperature and/or the brightness of the light source by using the switch, so that the use experience of a user is improved.

The foregoing description is only an overview of the technical solutions of the present invention, and the embodiments of the present invention are described below in order to make the technical means of the present invention more clearly understood and to make the above and other objects, features, and advantages of the present invention more clearly understandable.

The above and other objects, advantages and features of the present invention will become more apparent to those skilled in the art from the following detailed description of specific embodiments thereof, taken in conjunction with the accompanying drawings.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:

FIG. 1 shows a partial circuit schematic of a prior art LED driver circuit;

FIG. 2 shows a partial circuit schematic of a control circuit according to one embodiment of the present invention.

Detailed Description

Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

The embodiment of the invention provides a combined circuit, which is applied to an LED drive circuit, and referring to fig. 2, the topological structure of the LED drive circuit of the embodiment of the invention adopts a floating high-power factor BUCK circuit (namely a BUCK conversion circuit) to introduce the application process of the combined circuit of the invention. The combination circuit comprises a detection module 10 and a driving and logic conversion module 20 connected thereto. The detection module 10 is configured to detect a state of an external switch (not shown in fig. 2), generate a detection signal according to the detected state of the external switch, and send the detection signal to the driving and logic converting module 20. The driving and logic converting module 20 receives the detection signal from the detecting module 10, and generates a driving signal according to the detection signal, so as to drive the operating state of the discharging module 30 for discharging the output electrolytic capacitor EC1 of the LED driving circuit by using the state of the driving signal.

In this embodiment, the LED driving circuit has an output electrolytic capacitor EC1, and when the discharging module 30 is in the working state, the output electrolytic capacitor EC1 can be discharged. The following describes the driving process of the operation state of the discharging module 30 by the detecting module 10 and the driving and logic converting module 20. Specifically, when the external switch state is the off state, the detection signal generated by the detection module 10 according to the external switch state is at a low level, the driving signal generated by the driving and logic conversion module 20 according to the low level detection signal is at a high level, and the discharging module 30 is driven to operate, so that the discharging module 30 discharges the output electrolytic capacitor EC1 of the LED driving circuit. When the external switch state is the closed state, the detection signal generated by the detection module 10 according to the external switch state is at a high level, and the driving signal generated by the driving and logic converting module 20 according to the high-level detection signal is at a low level, at this time, the discharging module 30 does not operate, that is, the discharging module 30 does not discharge the output electrolytic capacitor EC 1.

The embodiment of the invention can be suitable for the working scene that the light source flickers when the LED driving circuit switches the color temperature and/or the brightness of the light source by using the switch so as to eliminate or control the flickers of the light source. When the color temperature and/or the brightness of the light source are switched by using the external switch, the detection module 10 and the driving and logic conversion module 20 cooperate with each other to drive the discharge module 30 to discharge the energy on the output electrolytic capacitor EC1, so that the problem that the light source flickers when emitting light due to the residual energy on the output electrolytic capacitor EC1 is avoided. Therefore, visual stroboflash can not occur in the process of switching the color temperature and/or the brightness of the light source by using the switch, and the use experience of a user is improved. Because the light source is easy to flicker when the color temperature and/or the brightness of the light source of the LED product with the high power factor are switched by the switch at present, the scheme of the invention can be well applied to the high-power LED product with the power factor of more than 0.7.

With continued reference to fig. 2, in one embodiment of the present invention, the detection module 10 includes a first resistor, a capacitor, a diode, and an auxiliary winding of a power inductor, the first resistor is connected in parallel with the capacitor, and the diode and the auxiliary winding of the power inductor are connected in series and then connected in parallel with the capacitor. In fig. 2, the first resistor is a resistor R6, the capacitor device is a capacitor C1, the diode is D1, the power inductor is L2, and the auxiliary windings of the power inductor L2 are pins 6 and 8.

If the external switch is closed, the voltage of the auxiliary winding of the power inductor L2 is a high-frequency pulsating alternating-current square wave, and the voltage on the auxiliary winding of the power inductor L2 is rectified and filtered through the diode D1 and the capacitor C1 to generate a high-level detection signal. If the external switch is off, the diode D1 is turned off, and a low-level detection signal is generated.

In this embodiment, the driving and logic converting module 20 includes a zener diode ZD1, resistors R7, R8, R10, R11, and a switching transistor (for example, a MOS transistor shown in fig. 2) Q3. One end of the zener diode ZD1 is connected to the capacitor C1, and the other end of the zener diode ZD1 is connected to the gate of the MOS transistor Q3. When the detection signal generated by the detection module 10 is at a low level, the zener diode ZD1 is turned off, and drives the MOS transistor Q3 to be turned off, and the output electrolytic capacitor EC1 is discharged through the discharge module 30. If the detection signal generated by the detection module 10 is at a high level, the zener diode ZD1 is turned on and broken down, and drives the MOS transistor Q3 to be turned on, and the discharge module 30 does not operate.

Based on the same inventive concept, the present invention further provides a control circuit, which is applied to the LED driving circuit, and with reference to fig. 2, the control circuit includes a discharging module 30, a switch module 40, and a combination circuit (including the detecting module 10 and the driving and logic converting module 20) in any of the above embodiments. The switch module 40 is connected to the at least two light sources, receives a switch switching signal from an external switch, and switches the color temperature and/or the brightness of the at least two light sources according to the switch switching signal. In which at least two light sources are used as the load of the LED driving circuit, this embodiment shows two light sources, one of which is WLED-for white LEDs and the other is YLED-for yellow LEDs. In this embodiment, the condition for generating the switch switching signal by the external switch may be that if the external switch is in a closed state, the switch switching signal is generated when the external switch is opened and then closed. The number of the branches of the light source is not particularly limited in the embodiment of the present invention.

The discharging module 30 is connected to the switch module 40 and the driving and logic converting module 20, respectively, and receives the driving signal output by the driving and logic converting module 20, so as to drive the self state by using the state of the driving signal, and discharge the output electrolytic capacitor of the LED driving circuit when the self state is the working state, so that the output electrolytic capacitor EC1 does not discharge through the current light emitting source after the color temperature and/or brightness of at least two light sources are switched by the switch module 40.

In this embodiment, the control circuit may be applied to a working scene in which the LED driving circuit flickers when the color temperature and/or brightness of the light source is switched by the switch. The color temperature switching refers to switching of light sources with different colors, and if the control circuit application scene is a scene for switching the color temperature of the light sources, at the moment, at least two light sources comprise light sources with at least two colors, and the color of each light source is different. For example, one light source is white, and the other light source is yellow, then the control circuit may perform color temperature switching between white and yellow, and of course, the control circuit may further include light sources of other colors, which is not specifically limited in this embodiment of the present invention. The control circuit of the embodiment shown in fig. 2 is applied to a scene of switching color temperature.

The brightness switching refers to switching of light sources with different brightness, and if the application scene of the control circuit is a scene of switching the brightness of the light sources, the number of each light source in at least two light sources is different. For example, if the number of one path of light source is 3 and the number of the other path of light source having the same type is 5, the control circuit may switch the brightness between 3 light sources and 5 light sources. Of course, the brightness can also be switched by arranging different types of light sources in at least two light sources, for example, three light sources, which have the same number, one light source is 3W, and the other two light sources are respectively 5W and 8W, so that the brightness switching of the LED can also be realized.

Certainly, the color temperature and the brightness can also be switched simultaneously, at this time, the at least two light sources include light sources of at least two colors, and the color and the number of each light source are different.

In an embodiment of the present invention, the process of the discharging module 30 driving its own working state according to the driving signal output by the driving and logic converting module 20 may include: if the driving signal is at a low level, the discharging module 30 drives its own working state to be off according to the driving signal at the low level. If the driving signal is at a high level, the discharging module 30 drives its own working state to work according to the driving signal at the high level.

In this embodiment, the discharging module 30 includes a second resistor and a transistor, wherein one end of the second resistor is connected to the collector of the transistor, and the other end of the second resistor is connected to one end of the output electrolytic capacitor EC 1. The other end of the output electrolytic capacitor EC1 is connected with the emitter of the triode. In fig. 2, the second resistor is a resistor R9, and the transistor is a transistor Q4. If the external switch is off, the detection module 10 generates a low level detection signal according to the switch state, the zener diode ZD1 is turned off, the driving MOS transistor Q3 is turned off, the driving MOS transistor Q4 is turned high, that is, the transistor Q4 is turned on, and the output capacitor EC1 discharges through the resistor R9 and the transistor Q4.

In order to more clearly embody the embodiment of the present invention, the operation process of the switching module 40 for switching the LEDs emitting different colors and the discharging module 30 during the switching process will be described.

Referring to fig. 2, in this embodiment, when the light source LEDs (i.e., WLED — and YLED — shown in fig. 2, where WLED represents a white LED and YLED represents a yellow LED) normally operate, and DRV _ SW (i.e., driver) is at a low level, the transistor Q4 of the discharging module 30 is turned off, the transistor Q1 is turned on, the transistor Q2 is turned off, and the white LED is turned on.

When DRV _ SW is high, transistor Q4 is on, and Q1 and Q2 are both off. Since the resistance of the resistor R9 in series with the transistor Q4 is extremely small. Therefore, the energy in the output electrolytic capacitor EC1 is rapidly discharged through the resistor R9 and the transistor Q4 of the discharging module 30. The resistance value of the resistor R9 can be determined according to the actual circuit and the output capacitance value, generally, the resistance value of the resistor R9 can be selected between 100K ohms and 1K ohms, and the embodiment of the invention does not specifically limit the resistance value of R9.

When the DRV _ SW reaches the low level again, the triode Q4 is cut off, the Q1 is cut off, the Q2 is conducted, and the yellow LED is bright. The energy on the electrolytic capacitor EC1 is discharged through the resistor R9 and the triode Q4 after the last switch is turned off. Therefore, the residual energy on the output electrolytic capacitor EC1 does not cause the LED to flicker before the operation of the switch module 40 is started. After the switch module 40 starts to work, the switch module 40 can normally complete the function of switching the color temperature of the LED. Therefore, visual stroboflash can not occur in the process of switching the color temperature of the LED by the switch.

Similarly, in a scene of switching the brightness of the light source by using the switch, the visual stroboscopic in the switching process can be eliminated by adopting the mode. At this time, in the at least two light sources, each light source includes a different number of LEDs, and switching of the light source brightness can be achieved by switching between the branches of the different numbers of LEDs.

Moreover, in the lighting equipment which simultaneously switches the brightness and the color temperature of the light source by using the switch, the visual stroboscopic in the switch switching process can be eliminated in the manner. At the moment, in the at least two light sources, each light source comprises different numbers of LEDs, the colors of the LEDs in each path are different, and the switching of the brightness and the color temperature of the light source can be realized by switching the switches in the branches of the LEDs with different numbers and different colors.

In another embodiment of the present invention, the control circuit further includes a linear regulator 50, and the linear regulator 50 is connected to the detection module 10, receives the detection signal of the detection module 10, and provides a stable voltage for the driving and logic converting module 20 according to the detection signal.

The control circuit of the embodiment of the invention can be applied to any topological structure of the LED driving circuit, and in the embodiment shown in fig. 2, the buck circuit adopted by the topological structure includes a capacitor C3, a switching tube (i.e., MOS tube) Q6, an L2 main winding (i.e., pins 2 and 4), a freewheeling diode D2 and an output electrolytic capacitor EC 1. The gate of the MOS transistor Q6 is connected to a driver IC (integrated circuit), which is a control IC (not shown) of the LED driver circuit and is referred to as IC 1. In addition, the control circuit may further include a special color temperature/brightness switching control IC or a single chip, which is referred to as IC2 (not shown in the drawings), the IC2 and its peripheral circuits may synchronously detect the switching status of the switch, and the IC2 also has its own detection circuit (the detection circuit here is different from the detection module 10 described above). When IC2 receives a switch control signal for an external switch, switch switching signals, DRV _ W and DRV _ Y in fig. 2, may be generated for switching between WLED-and YLED-.

The following describes the entire operation of the control circuit according to the embodiment of the present invention.

When the external switch is turned on, the LED driving circuit operates normally, the voltage across the main winding (i.e., pins 2 and 4) of the power inductor L2 in the detection module 10 is a high-frequency pulsating ac square wave, and the voltage across the auxiliary winding (i.e., pins 6 and 8) of the power inductor L2 after magnetic coupling is also a high-frequency pulsating ac square wave. The voltage on the auxiliary winding of the power inductor L2 is rectified and filtered by the diode D1 and the capacitor C1 of the detection module 10, and Vcc _ aux is high. In the embodiment of the present invention, the high level voltage value of Vcc _ aux is about 12V. Of course, the high level voltage value of Vcc _ aux may also adopt other voltage values, which is not specifically limited in the embodiment of the present invention. The high level of Vcc _ aux provides a 5V constant voltage output through a linear regulator source 50.

At this time, Vcc _ aux is high, so that zener diode ZD1 in driving and logic converting module 20 is turned on and broken down, driving MOS transistor Q3 is turned on, driving transistor Q4 of discharging module 30 is turned off, and transistor Q4 is turned off. The transistor Q4 and the resistor R9 of the discharging module 30 are not operated, i.e., the discharging module 30 does not participate in the operation.

The external switch is turned off, the LED driving circuit stops operating, the voltage on the main winding (i.e., pins 2 and 4) of the power inductor L2 is zero, and the voltage on the auxiliary winding (i.e., pins 6 and 8) of the power inductor L2 after magnetic coupling is also zero. Since the capacitance value of the capacitor C1 is small, Vcc _ aux quickly becomes low (i.e., Vcc _ aux voltage is zero). Because the output end of the linear voltage stabilizing source 50 is provided with a large electrolytic capacitor EC2, 5V is still maintained for a short time after the circuit is powered off.

At this time, Vcc _ aux is low, so that zener diode ZD1 is turned off, MOS transistor Q3 is turned off, transistor Q4 is driven high, and transistor Q4 is turned on. The transistor Q4 and the resistor R9 operate, i.e., the discharge module 30 operates. The energy in the output electrolytic capacitor EC1 is rapidly released through the resistor R9 and the transistor Q4, and the voltage in the output electrolytic capacitor EC1 is nearly zero.

The external switch is closed again, Vcc _ aux quickly goes high, MOS transistor Q3 is turned on, and transistor Q4 is turned off. The electrolytic capacitor EC1 will gradually increase with the operating voltage of the switcher module 40 until the currently operating LED is fully lit.

So far, the whole circuit accomplishes the colour temperature switching function of LED lighting apparatus to, the stroboscopic of vision can not appear at the switch switching colour temperature in-process of LED lighting apparatus. Similarly, the same applies when the brightness of the light source is switched by the switch, or when the brightness and the color temperature of the light source are simultaneously switched by the switch.

In the description provided herein, numerous specific details are set forth. It is understood, however, that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

Similarly, it should be appreciated that in the foregoing description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. However, the disclosed method should not be interpreted as reflecting an intention that: that the invention as claimed requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.

Thus, it should be appreciated by those skilled in the art that while a number of exemplary embodiments of the invention have been illustrated and described in detail herein, many other variations or modifications consistent with the principles of the invention may be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the invention. Accordingly, the scope of the invention should be understood and interpreted to cover all such other variations or modifications.

Claims

1. A combined circuit applied to an LED drive circuit comprises: a detection module and a drive and logic conversion module connected with the detection module, wherein,

the driving and logic conversion module receives the detection signal from the detection module, generates a driving signal according to the detection signal, and drives the working state of a discharging module for discharging an output electrolytic capacitor of the LED driving circuit by using the state of the driving signal;

if the external switch state is off, the detection module generates a low level detection signal according to the external switch state, the driving and logic conversion module generates a high level driving signal according to the low level detection signal, and drives the discharging module to work, so that the discharging module discharges the output electrolytic capacitor of the LED driving circuit.

2. The combination circuit of claim 1,

if the external switch state is closed, the detection signal generated by the detection module according to the external switch state is a high level, the driving signal generated by the driving and logic conversion module according to the high level detection signal is a low level signal, and the discharging module does not work.

3. The combination circuit of claim 2,

the detection module comprises a first resistor, a capacitor device, a diode and an auxiliary winding of a power inductor, wherein the first resistor is connected with the capacitor device in parallel, and the diode and the auxiliary winding of the power inductor are connected in series and then connected with the capacitor device in parallel;

if the external switch is closed, the voltage of the auxiliary winding of the power inductor is a high-frequency pulsating alternating-current square wave, and the voltage on the auxiliary winding of the power inductor is rectified and filtered by the diode and the capacitor device to generate a high-level detection signal; if the external switch is off, the diode is cut off and generates a low-level detection signal.

4. The combination circuit of claim 3, wherein the driving and logic converting module comprises a voltage regulator diode and a MOS transistor, wherein one end of the voltage regulator diode is connected with the capacitor device, and the other end of the voltage regulator diode is connected with the gate of the MOS transistor;

if the detection signal generated by the detection module is at a low level, the voltage stabilizing diode is cut off, the MOS tube is cut off, and a high-level driving signal is generated and sent to the discharge module, and the electrolytic capacitor is output to discharge through the discharge module;

if the detection signal generated by the detection module is at a high level, the voltage stabilizing diode is conducted and broken down to drive the MOS tube to be conducted, and a low-level driving signal is generated to the discharge module, and the discharge module does not work.

5. A control circuit for an LED driver circuit, comprising a switch module, a discharge module, and the combination circuit of any one of claims 1-4,

6. The control circuit of claim 5, wherein the control circuit is configured to control or eliminate the LED driver circuit from flickering of the light source when the color temperature and/or brightness of the light source is switched by the switch.

7. The control circuit according to claim 5 or 6, wherein the condition under which the external switch generates the switching signal comprises: if the external switch is in a closed state, a switch switching signal is generated when the external switch is opened and then closed.

8. The control circuit of claim 5 or 6,

the discharging module comprises a second resistor and a triode, one end of the second resistor is connected with a collector of the triode, the other end of the second resistor is connected with one end of the output electrolytic capacitor, and the other end of the output electrolytic capacitor is connected with an emitting electrode of the triode;

if the external switch state is off, the detection module of the combination circuit is at a low level according to the detection signal generated by the switch state, the driving and logic conversion module generates a driving signal at a high level according to the detection signal at the low level and drives the triode to be connected, and the output de-capacitor discharges through the second resistor and the triode.

9. The control circuit according to claim 5 or 6, wherein the at least two light sources comprise light sources of at least two colors, and the color of each light source is different.

10. The control circuit according to claim 5 or 6, wherein the number of each of the at least two light sources is different.

11. The control circuit according to claim 5 or 6, wherein the at least two light sources comprise at least two color light sources, and the color and the number of each light source are different.

12. The control circuit according to claim 5 or 6, characterized by further comprising:

and the linear voltage stabilization source is connected with the detection module of the combined circuit, receives the detection signal of the detection module and provides stable voltage for the driving and logic conversion module according to the detection signal.