CN105007667A - LED dimming circuit - Google Patents
LED dimming circuit Download PDFInfo
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- CN105007667A CN105007667A CN201510467808.5A CN201510467808A CN105007667A CN 105007667 A CN105007667 A CN 105007667A CN 201510467808 A CN201510467808 A CN 201510467808A CN 105007667 A CN105007667 A CN 105007667A
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Abstract
The invention discloses an LED dimming circuit comprising a dimming signal generation circuit, a dimming signal conversion circuit, a PWM control circuit, and an LED driver circuit. The dimming signal generation circuit is used to generate a dimming signal. The dimming signal conversion circuit is used to receive a zero line signal and the dimming signal output by the dimming signal generation circuit and generate a first square wave signal and a second square wave signal according to the zero line signal and the dimming signal. The PWM control circuit is used to adjust the duty ratio of a PWM signal according to the first square wave signal and the second square wave signal and output the PWM signal to the LED driver circuit. The LED driver circuit is used to drive an LED to emit light according to the PWM signal. According to the invention, the brightness of an LED lighting lamp is controlled by a single live line. Neither remote controller nor control line is needed. Power line relaying is not needed. Replacing and upgrading of an ordinary lamp can be realized. The cost is low. The anti-interference ability is strong.
Description
Technical field
The present invention relates to LED technology field, particularly relate to a kind of LED light adjusting circuit.
Background technology
LED strictly must control to meet its operating characteristic and reliable, requirement efficiently, so general LED all needs to be equipped with special driving power because of it to operating voltage, electric current.And user is also having different demands to light illumination on different opportunity; As we need light fixture can with high-high brightness work to meet our needs to illumination sometimes, otherwise we then need it can reduce brightness to meet our requirement to more weak light filling sometimes, also save the consumption of electric energy simultaneously.So to LED brightness adjustment control while meeting the more demands of user also to preventing global warming from making contributions; Again because user is to LED requirement of light regulation: have excellent linear, broad dimming scope (brightness 0-100% regulates), higher stability, high efficiency, High Power Factor, low EMI, low cost realization etc., the LED therefore with excellent dimming characteristic drives and just seems more important.
Traditional LED light modulation adopts two line power line carriers to control light modulation, is modulated by dimming control signal through higher frequency, by power supply zero, fiery two line transmission after isolated variable, then takes out the signal needed in terminal; Utilize the dimming control signal control LED or gas discharge lamp current of taking out to reach the object of light modulation.The method advantage is mainly: light modulation good linearity, wide ranges can reach 0 ~ 100%, and electromagnetic interference is little, and line power factor can do very high, and reliability is higher.Shortcoming is mainly: have particular/special requirement to subscriber's line, and its dimmer must the fiery two-wire power supply of 220V zero, and carrier signal need transmit via zero fiery two lines superpositions, particular/special requirement is had to subscriber's line, make troubles to user, and add holistic cost, limit it and promote the use of.
Summary of the invention
The embodiment of the present invention proposes a kind of LED light adjusting circuit, its can effectively solve existing light adjusting circuit light modulation linearly bad, consistency is poor, inefficient, low power factor, high expensive, can not mate, have the problems such as particular/special requirement to new subscriber's line with original subscriber's line.
The embodiment of the present invention provides a kind of LED light adjusting circuit, comprises dim signal and produces circuit, dim signal change-over circuit, pwm control circuit and LED drive circuit;
Described dim signal produces circuit and comprises light modulation setup unit, mains switch, the first optocoupler, the first controllable silicon, the first pull-up resistor, the first diode, the second pull-up resistor, the second optocoupler, the second controllable silicon, the first divider resistance, the second diode and the second divider resistance, and has live wire signal input part, dim signal output, the first control signal input and the second control signal input; The first end of described mains switch connects described live wire signal input part; The first input end of described first optocoupler is connected with direct voltage by described first pull-up resistor, and the second input of described first optocoupler is connected with described first control signal input; First output of described first optocoupler is connected with the negative pole of described first diode, and the second output of described first optocoupler controls pole with described first silicon controlled and is connected; Described first silicon controlled negative electrode is connected with the second end of described mains switch; Described first silicon controlled anode is connected with described dim signal output, and is connected with the positive pole of described first diode by described first divider resistance; The first input end of described second optocoupler is connected with direct voltage by described second pull-up resistor, and the second input of described second optocoupler is connected with described second control signal input; First output of described second optocoupler is connected with the negative pole of described second diode, and the second output of described second optocoupler controls pole with described second silicon controlled and is connected; Described second silicon controlled anode is connected with the second end of described mains switch, and is connected with the positive pole of described first diode by described second divider resistance; Described second silicon controlled negative electrode is connected with described dim signal output;
Described light modulation setup unit is for controlling the level of described first control signal input or described second control signal input;
Described dim signal change-over circuit for receiving the dim signal of neutral signal and the output of described dim signal generation circuit, and produces the first square-wave signal and the second square-wave signal according to described neutral signal and described dim signal;
Described pwm control circuit is used for according to described first square-wave signal and described second square-wave signal, adjusts the duty ratio of pwm signal and outputs to described LED drive circuit; Wherein, the square wave number that described pwm control circuit lacks for detecting described first square-wave signal, and the duty ratio improving described PWM ripple according to the square wave number that described first square-wave signal lacks; Described pwm control circuit also for detecting the square wave number that described second square-wave signal lacks, and reduces the duty ratio of described PWM ripple according to the square wave number that described second square-wave signal lacks;
Described LED drive circuit is used for driving described LED luminous according to described pwm signal.
In one embodiment, described dim signal change-over circuit comprises the first resistance, the second resistance, the 3rd optocoupler, the 4th optocoupler, the 3rd resistance, the 4th resistance, the 5th resistance, the 6th resistance, the 7th resistance, the first electric capacity, the second electric capacity, the first inverter and the second inverter; The first end of described first resistance is for receiving described dim signal; Second end of described first resistance is connected with the first input end of described 3rd optocoupler, and is connected with the second input of described 4th optocoupler; The first end of described second resistance is for receiving neutral signal; Second end of described second resistance is connected with the first input end of described 4th optocoupler, and is connected with the second input of described 3rd optocoupler;
First output of described 3rd optocoupler connects direct voltage by described 3rd resistance, and the second output of described 3rd optocoupler is by described 4th grounding through resistance; The first end of described 5th resistance is connected with the second output of described 3rd optocoupler, and the second end of described 5th resistance is connected with the input of described first inverter, and by described first capacity earth; The output of described first inverter exports described first square-wave signal;
First output of described 4th optocoupler connects direct voltage by described 6th resistance, and the second output of described 4th optocoupler is by described 7th grounding through resistance; The first end of described 8th resistance is connected with the second output of described 4th optocoupler, and the second end of described 8th resistance is connected with the input of described second inverter, and by described second capacity earth; The output of described second inverter exports described second square-wave signal.
In another embodiment, described dim signal change-over circuit comprises the first low pass active filter circuit, a RC filter circuit, the first voltage follower circuit, the first bleeder circuit, the first comparison circuit, the second low pass active filter circuit, the 2nd RC filter circuit, the second voltage follower circuit, the second bleeder circuit and the second comparison circuit;
The input of described first low pass active filter circuit is for receiving described dim signal, and the output of described first low pass active filter circuit is connected to the first input end of described first comparison circuit successively by a described RC filter circuit and the first voltage follower circuit; The first input end of described first comparison circuit is connected to the second input of described second comparison circuit by described first bleeder circuit; The output of described first comparison circuit exports described first square-wave signal;
The input of described second low pass active filter circuit is for receiving described neutral signal, and the output of described second low pass active filter circuit is connected to the first input end of described second comparison circuit successively by described 2nd RC filter circuit and the second voltage follower circuit; The first input end of described second comparison circuit is connected to the second input of described first comparison circuit by described second bleeder circuit; The output of described second comparison circuit exports described second square-wave signal.
Further, described first low pass active filter circuit comprises the first resistance, the second resistance, the first electric capacity, the first operational amplifier and the 3rd resistance; The first end of described first resistance is the input of described first low pass active circuit, and the second end of described first resistance is by described second grounding through resistance; Described first electric capacity and described second resistor coupled in parallel; Second end of described first resistance is connected with the normal phase input end of described first operational amplifier; The two ends of described 3rd resistance connect inverting input and the output of described first operational amplifier respectively; The output of described first operational amplifier is the output of described first low pass active filter circuit;
Described second low pass active filter circuit comprises the 4th resistance, the 5th resistance, the second electric capacity, the second operational amplifier and the 6th resistance; The first end of described 4th resistance is the input of described second low pass active circuit, and the second end of described 4th resistance is by described 5th grounding through resistance; Described second electric capacity and described 5th resistor coupled in parallel; Second end of described 4th resistance is connected with the normal phase input end of described second operational amplifier; The two ends of described 6th resistance connect inverting input and the output of described second operational amplifier respectively; The output of described second operational amplifier is the output of described second low pass active filter circuit.
Further, a described RC filter circuit comprises the 7th resistance and the 3rd electric capacity; The first end of described 7th resistance is connected with the output of described first low pass active filter circuit, and the second end of described 7th resistance is by described 3rd capacity earth; The output of described 7th resistance is the output of a described RC filter circuit;
Described 2nd RC filter circuit comprises the 8th resistance and the 4th electric capacity; The first end of described 8th resistance is connected with the output of described second low pass active filter circuit, and the second end of described 8th resistance is by described 4th capacity earth; The output of described 8th resistance is the output of described 2nd RC filter circuit.
Further, described first voltage follower circuit comprises the 3rd operational amplifier and the 9th resistance; The normal phase input end of described 3rd operational amplifier is the input of described first voltage follower circuit, the output of described 3rd operational amplifier is the output of described first voltage follower circuit, and the two ends of described 9th resistance connect inverting input and the output of described 3rd operational amplifier respectively;
Described second voltage follower circuit comprises four-operational amplifier and the tenth resistance; The normal phase input end of described four-operational amplifier is the input of described second voltage follower circuit, the output of described four-operational amplifier is the output of described second voltage follower circuit, and the two ends of described tenth resistance connect inverting input and the output of described four-operational amplifier respectively.
Further, described first bleeder circuit comprises the 11 resistance and the 12 resistance; The first end of described 11 resistance is the input of described first bleeder circuit, and the second end of described 11 resistance is the output of described first bleeder circuit; Second end of described 11 resistance is by described 12 grounding through resistance;
Described second bleeder circuit comprises the 13 resistance and the 14 resistance; The first end of described 13 resistance is the input of described second bleeder circuit, and the second end of described 13 resistance is the output of described second bleeder circuit; Second end of described 13 resistance is by described 14 grounding through resistance.
Further, described first comparison circuit comprises the 5th operational amplifier and the 15 resistance; The inverting input of described 5th operational amplifier is the first input end of described first comparison circuit, the normal phase input end of described 5th operational amplifier is the second input of described first comparison circuit, the output of described 5th operational amplifier is the output of described first comparison circuit, and the two ends of described 15 resistance connect normal phase input end and the output of described 3rd operational amplifier respectively;
Described second comparison circuit comprises the 6th operational amplifier and the 16 resistance; The inverting input of described 6th operational amplifier is the first input end of described second comparison circuit, the normal phase input end of described 6th operational amplifier is the second input of described second comparison circuit, the output of described 6th operational amplifier is the output of described second comparison circuit, and the two ends of described 16 resistance connect normal phase input end and the output of described 6th operational amplifier respectively.
In one embodiment, described LED drive circuit comprises the 18 resistance, the 19 resistance, the first triode, the 20 resistance; The first end of described 18 resistance is the input of described LED drive circuit; Second end of described 18 resistance is connected with the base stage of described first triode, and by described 19 grounding through resistance; The grounded emitter of described first triode; The output of the very described LED drive circuit of current collection of described first triode, is connected with direct voltage by described 20 resistance.
In another embodiment, described LED drive circuit comprises the 21 resistance, the second triode, the 22 resistance, the 23 resistance, the 24 resistance, the 6th electric capacity, the 3rd triode, the 4th triode and the 3rd diode; The first end of described 21 resistance is the input of described LED drive circuit, and the second end of described 21 resistance is connected to the base stage of described second triode; The grounded emitter of described second triode, the first end of collector electrode and described 22 resistance, the first end of described 23 resistance and the first end of described 24 resistance are connected; Second end ground connection of described 22 resistance; Second end of described 23 resistance is connected with the base stage of the base stage of described 3rd triode, described 4th diode, and by described 6th capacity earth; Second end of described 24 resistance is connected with direct voltage; The positive pole of described 3rd diode is connected with direct voltage, and negative pole is connected with the collector electrode of described 4th triode; The emitter of described 4th triode is connected, as the output of described LED drive circuit with the emitter of described 3rd triode; The grounded collector of described 3rd triode; The polarity of described 3rd triode and described 4th triode is contrary.
Accompanying drawing explanation
Fig. 1 is the structured flowchart of LED light adjusting circuit provided by the invention;
Fig. 2 is the circuit diagram of the dim signal generation circuit in Fig. 1;
Fig. 3 is the circuit diagram of described dim signal change-over circuit in one embodiment;
Fig. 4 is the structured flowchart of described dim signal change-over circuit in another embodiment;
Fig. 5 is the circuit diagram of the dim signal change-over circuit in Fig. 4;
Fig. 6 is the circuit diagram of described LED drive circuit in one embodiment;
Fig. 7 is the circuit diagram of described LED drive circuit in another embodiment.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, be clearly and completely described the technical scheme in the embodiment of the present invention, obviously, described embodiment is only the present invention's part embodiment, instead of whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art, not making the every other embodiment obtained under creative work prerequisite, belong to the scope of protection of the invention.
See Fig. 1, be the structured flowchart of the LED light adjusting circuit that the embodiment of the present invention provides, it comprises dim signal and produces circuit 1, dim signal change-over circuit 2, pwm control circuit 3 and LED drive circuit 4.
Described dim signal produces circuit 1 and has live wire signal input part L and dim signal output Lout; Described dim signal change-over circuit 2 has dim signal input, neutral signal input N, the first square wave signal output part Pulse+ and the second square wave signal output part Pulse-; Described pwm control circuit 3 has the first square wave signal input part, the second square wave signal input part and pwm signal output; Described LED drive circuit 4 has pwm signal input and drive singal output; Described live wire signal input part L is used for being connected with live wire; Described dim signal output Lout is connected with described dim signal input; Described neutral signal input N is used for being connected with zero line; Described first square wave signal output part Pulse+ is connected with described first square wave signal input part; Described second square wave signal output part Pulse-is connected with described second square wave signal input part; Described pwm signal output is connected with described pwm signal input; It is luminous that described drive singal output is used for driving LED.
See Fig. 2, it is the circuit diagram of the dim signal generation circuit 1 in Fig. 1.
Described dim signal produces circuit and comprises light modulation setup unit, mains switch S1, the first optocoupler OC1, the first controllable silicon SCR 1, first pull-up resistor Rp1, the first diode D1, the second pull-up resistor Rp2, the second optocoupler OC2, the second controllable silicon SCR 2, first divider resistance Rd1, the second diode D2 and the second divider resistance Rd2, and has live wire signal input part, dim signal output, the first control signal input and the second control signal input; The first end of described mains switch S1 connects described live wire signal input part; The first input end of described first optocoupler OC1 is connected with direct voltage by described first pull-up resistor Rp1, and second input of described first optocoupler OC1 is connected with described first control signal input CTL1; First output of described first optocoupler OC1 is connected with the negative pole of described first diode D1, and second output of described first optocoupler OC1 is connected with the control pole of described first controllable silicon SCR 1; The negative electrode of described first controllable silicon SCR 1 is connected with second end of described mains switch S1; The anode of described first controllable silicon SCR 1 is connected with described dim signal output, and is connected with the positive pole of described first diode D1 by described first divider resistance Rd1; The first input end of described second optocoupler OC2 is connected with direct voltage by described second pull-up resistor Rp2, and second input of described second optocoupler OC2 is connected with described second control signal input CTL2; First output of described second optocoupler OC2 is connected with the negative pole of described second diode D2, and second output of described second optocoupler OC2 is connected with the control pole of described second controllable silicon SCR 2; The anode of described second controllable silicon SCR 2 is connected with second end of described mains switch S1, and is connected with the positive pole of described first diode D1 by described second divider resistance Rd2; The negative electrode of described second controllable silicon SCR 2 is connected with described dim signal output;
Described light modulation setup unit is for controlling the level of described first control signal input or described second control signal input.
Wherein, described mains switch S1 produces the switch of circuit 1 as described dim signal, and live wire signal (sine wave signal) is input to described dim signal and produces circuit 1 after described mains switch S1 is closed.
In normal operating conditions, it is all low level that described light modulation setup unit controls described first control signal input CTL1 and described second control signal input CTL2, make the first optocoupler OC1 and second optocoupler OC2 all conductings, suppose that AC sine signal is current and be in the positive half wave stage, when forward alternating voltage rises to conducting voltage between the anode of the second controllable silicon SCR 2 and negative electrode, now control pole and also reach trigger voltage simultaneously, then the second controllable silicon SCR 2 conducting, until when forward voltage drops to below SCR2 conducting voltage, Q2 automatically shuts down; In like manner, the negative half-wave stage is in when AC sine signal is current, when Opposed crossing voltage rise is to conducting voltage between the first controllable silicon Q1 anode and negative electrode, now control pole and also reach trigger voltage simultaneously, then the first controllable silicon SCR 1 conducting, until when forward voltage drops to below the first controllable silicon SCR 1 conducting voltage, the first controllable silicon SCR 1 automatically shuts down.
When needs cut away positive half wave, only need to the second control signal input CTL2 input high level simultaneously to the first control signal input CTL1 input low level, i.e. the first optocoupler OC1 conducting and the second optocoupler OC2 ends, then the second controllable silicon SCR 2 does not have trigger voltage, even if AC signal is in positive half wave, second controllable silicon SCR 2 also cannot conducting, but the first controllable silicon SCR 1 can normally when AC signal is in negative half-wave; Therefore now described dim signal only has the waveform of negative half-wave, and namely positive half wave is cut away, and positive half wave is depended on to the duration of the second control signal input CTL2 input high level by the number cut away.
On the contrary, when needs cut away negative half-wave, give the second control signal input CTL2 input low level to the first control signal input CTL1 input high level simultaneously, then the first optocoupler OC1 ends and the second optocoupler OC2 conducting, then the first controllable silicon SCR 1 does not have trigger voltage, also cannot conducting even if AC signal is in negative half-wave first controllable silicon SCR 1, but when AC signal is in positive half wave, the second controllable silicon SCR 2 can normally.Therefore now described dim signal only has the waveform of positive half wave, and namely negative half-wave is cut away, and negative half-wave is depended on to the time of the first control signal input CTL1 input high level by the number cut away.
Concerning user, light modulation can be carried out by the grade setting light.Such as, the grade of light has 10 grades, and is currently in the 5th grade, and user inputs light modulation to the 6th grade, namely needs the light of an increase grade.Described light modulation setup unit calculates the time required for light of a raising grade, and controls described second control signal input CTL2 keep high level within this period.The time length of copped wave accurately can be controlled by described light modulation setup unit.
As more preferably, described dim signal produces circuit 1 and also comprises the 17 resistance R17 and the 5th electric capacity C5; Described 17 resistance R17 and described 5th electric capacity C5 series circuit in series, the two ends of described series circuit connect second end of described mains switch S1 and described dim signal output Lout respectively.Described 17 resistance and described 5th electric capacity C5 are used for target signal filter more than power frequency, reduce signal disturbing.
Described dim signal change-over circuit 2 for receiving the dim signal of neutral signal and the output of described dim signal generation circuit 1, and produces the first square-wave signal and the second square-wave signal according to described neutral signal and described dim signal.
As shown in Figure 3, it is the circuit diagram of described dim signal change-over circuit in one embodiment.
Described dim signal change-over circuit comprises the first resistance R1, the second resistance R2, the 3rd optocoupler OC3, the 4th optocoupler OC4, the 3rd resistance R3, the 4th resistance R4, the 5th resistance R5, the 6th resistance R6, the 7th resistance R7, the first electric capacity C1, the second electric capacity C2, the first inverter T1 and the second inverter T2; The first end of described first resistance R1 is for receiving described dim signal; Second end of described first resistance R1 is connected with the first input end of described 3rd optocoupler OC3, and is connected with second input of described 4th optocoupler OC4; The first end of described second resistance R2 is for receiving neutral signal; Second end of described second resistance R2 is connected with the first input end of described 4th optocoupler OC4, and is connected with second input of described 3rd optocoupler OC3;
First output of described 3rd optocoupler OC3 connects direct voltage by described 3rd resistance R3, and second output of described 3rd optocoupler OC3 is by described 4th resistance R4 ground connection; The first end of described 5th resistance R5 is connected with second output of described 3rd optocoupler OC3, and second end of described 5th resistance R5 is connected with the input of described first inverter T1, and by described first electric capacity C1 ground connection; The output of described first inverter T1 exports described first square-wave signal;
First output of described 4th optocoupler OC4 connects direct voltage by described 6th resistance R6, and second output of described 4th optocoupler OC4 is by described 7th resistance R7 ground connection; The first end of described 8th resistance R8 is connected with second output of described 4th optocoupler OC4, and second end of described 8th resistance R8 is connected with the input of described second inverter T2, and by described second electric capacity C2 ground connection; The output of described second inverter T2 exports described second square-wave signal.
In the present embodiment, realize light-coupled isolation by the 3rd optocoupler OC3 and the 4th optocoupler OC4, when dim signal is in positive half wave, the 3rd optocoupler OC3 conducting, the 4th optocoupler OC4 ends, and the first inverter T1 exports high level, the second inverter T2 output low level; When dim signal is in negative half-wave, the 4th optocoupler OC4 conducting, the 3rd optocoupler OC3 ends, and the first inverter T1 exports as low level, and the second inverter T2 exports high level.Namely the first inverter T1 and the second inverter T2 exports the square wave of 0-5V respectively, and frequency is about 50Hz, and the time approximately differs half period.When cutting away the positive half wave of AC signal, described first inverter T1 output low level, described second inverter T2 exports the square wave of 0-5V, and frequency is about 50Hz.In like manner, when cutting away the negative half-wave of AC signal, described second inverter T2 output low level, described first inverter T1 exports the square wave of 0-5V, and frequency is about 50Hz.
See Fig. 4, it is the structured flowchart of described dim signal change-over circuit in another embodiment.Described dim signal change-over circuit 2 comprises the first low pass active filter circuit 211, RC filter circuit 212, first voltage follower circuit 213, first bleeder circuit 214, first comparison circuit 215, a second low pass active filter circuit 221, the 2nd RC filter circuit 222, second voltage follower circuit 223, second bleeder circuit 224 and the second comparison circuit 225;
The input of described first low pass active filter circuit 211 is for receiving described dim signal, and the output of described first low pass active filter circuit 211 is connected to the first input end of described first comparison circuit 215 successively by a described RC filter circuit 212 and the first voltage follower circuit 213; The first input end of described first comparison circuit 215 is connected to the second input of described second comparison circuit 225 by described first bleeder circuit 214; The output of described first comparison circuit 215 exports described first square-wave signal;
The input of described second low pass active filter circuit 221 is for receiving described neutral signal, and the output of described second low pass active filter circuit 221 is connected to the first input end of described second comparison circuit 225 successively by described 2nd RC filter circuit 222 and the second voltage follower circuit 223; The first input end of described second comparison circuit 225 is connected to the second input of described first comparison circuit 215 by described second bleeder circuit 224; The output of described second comparison circuit 225 exports described second square-wave signal.
Particularly, as shown in Figure 5, it is the circuit diagram of the dim signal change-over circuit in Fig. 4.
Described first low pass active filter circuit 211 comprises the first resistance R1, the second resistance R2, the first electric capacity C1, the first operational amplifier A 1 and the 3rd resistance R3; The first end of described first resistance R1 is the input of described first low pass active circuit, and second end of described first resistance R1 is by described second resistance R2 ground connection; Described first electric capacity C1 is in parallel with described second resistance R2; Second end of described first resistance R1 is connected with the normal phase input end of described first operational amplifier A 1; The two ends of described 3rd resistance R3 connect inverting input and the output of described first operational amplifier A 1 respectively; The output of described first operational amplifier A 1 is the output of described first low pass active filter circuit 211;
Described second low pass active filter circuit 221 comprises the 4th resistance R4, the 5th resistance R5, the second electric capacity C2, the second operational amplifier A 2 and the 6th resistance R6; The first end of described 4th resistance R4 is the input of described second low pass active circuit, and second end of described 4th resistance R4 is by described 5th resistance R5 ground connection; Described second electric capacity C2 is in parallel with described 5th resistance R5; Second end of described 4th resistance R4 is connected with the normal phase input end of described second operational amplifier A 2; The two ends of described 6th resistance R6 connect inverting input and the output of described second operational amplifier A 2 respectively; The output of described second operational amplifier A 2 is the output of described second low pass active filter circuit 221.
A described RC filter circuit 212 comprises the 7th resistance R7 and the 3rd electric capacity C3; The first end of described 7th resistance R7 is connected with the output of described first low pass active filter circuit 211, and second end of described 7th resistance R7 is by described 3rd electric capacity C3 ground connection; The output of described 7th resistance R7 is the output of a described RC filter circuit 212;
Described 2nd RC filter circuit 222 comprises the 8th resistance R8 and the 4th electric capacity C4; The first end of described 8th resistance R8 is connected with the output of described second low pass active filter circuit 221, and second end of described 8th resistance R8 is by described 4th electric capacity C4 ground connection; The output of described 8th resistance R8 is the output of described 2nd RC filter circuit 222.
Described first voltage follower circuit 213 comprises the 3rd operational amplifier A 3 and the 9th resistance R9; The normal phase input end of described 3rd operational amplifier A 3 is the input of described first voltage follower circuit 213, the output of described 3rd operational amplifier A 3 is the output of described first voltage follower circuit 213, and the two ends of described 9th resistance R9 connect inverting input and the output of described 3rd operational amplifier A 3 respectively;
Described second voltage follower circuit 223 comprises four-operational amplifier R4 and the tenth resistance R10; The normal phase input end of described four-operational amplifier R4 is the input of described second voltage follower circuit 223, the output of described four-operational amplifier R4 is the output of described second voltage follower circuit 223, and the two ends of described tenth resistance R10 connect inverting input and the output of described four-operational amplifier R4 respectively.
Described first bleeder circuit 214 comprises the 11 resistance R11 and the 12 resistance R12; The first end of described 11 resistance R11 is the input of described first bleeder circuit 214, and second end of described 11 resistance R11 is the output of described first bleeder circuit 214; Second end of described 11 resistance R11 is by described 12 resistance R12 ground connection;
Described second bleeder circuit 224 comprises the 13 resistance R13 and the 14 resistance R14; The first end of described 13 resistance R13 is the input of described second bleeder circuit 224, and second end of described 13 resistance R13 is the output of described second bleeder circuit 224; Second end of described 13 resistance R13 is by described 14 resistance R14 ground connection.
Described first comparison circuit 215 comprises the 5th operational amplifier A the 5 and the 15 resistance R15; The inverting input of described 5th operational amplifier A 5 is the first input end of described first comparison circuit 215, the normal phase input end of described 5th operational amplifier A 5 is the second input of described first comparison circuit 215, the output of described 5th operational amplifier A 5 is the output of described first comparison circuit 215, and the two ends of described 15 resistance R15 connect normal phase input end and the output of described 3rd operational amplifier A 3 respectively;
Described second comparison circuit 225 comprises the 6th operational amplifier A the 6 and the 16 resistance R16; The inverting input of described 6th operational amplifier A 6 is the first input end of described second comparison circuit 225, the normal phase input end of described 6th operational amplifier A 6 is the second input of described second comparison circuit 225, the output of described 6th operational amplifier A 6 is the output of described second comparison circuit 225, and the two ends of described 16 resistance R16 connect normal phase input end and the output of described 6th operational amplifier A 6 respectively.
Wherein, described first low-pass active filter is used for the HFS filtering of the dim signal to input, and a described RC filter circuit 212 is for putting down half-wave filter; The input impedance of described first voltage follower is very high, and output impedance is very low, therefore can play buffer action between prime and the input and output of rear class.In like manner, described second low-pass active filter is used for the HFS filtering of the neutral signal to input, and described 2nd RC filter circuit 222 is for putting down half-wave filter; The input impedance of described second voltage follower is very high, and output impedance is very low, therefore can play buffer action between prime and the input and output of rear class.
By comparing upper and lower 2 road signal voltages, when not carrying out copped wave to AC signal, the first comparison circuit 215 and the second comparison circuit 225 export the square wave of 0-5V respectively, and frequency is about 50Hz, and the time approximately differs half period.When cutting away the positive half wave of AC signal, described first comparison circuit 215 output low level, described second comparison circuit 225 exports the square wave of 0-5V, and frequency is about 50Hz.In like manner, when cutting away the negative half-wave of AC signal, described second comparison circuit 225 output low level, described first comparison circuit 215 exports the square wave of 0-5V, and frequency is about 50Hz.
Described pwm control circuit 3, for according to described first square-wave signal and described second square-wave signal, adjusts the duty ratio of pwm signal and outputs to described LED drive circuit 4; Wherein, described pwm control circuit 3 is when detecting that described first square-wave signal has lacked a square wave, improve duty ratio grade of described pwm signal, or when detecting that described second square-wave signal has lacked a square wave, reduce duty ratio grade of described pwm signal.
In one embodiment, described pwm control circuit 3 comprises the control chip of model STM8S103F2P6, and the 19th pin of described control chip is for receiving described first square-wave signal, 20th pin of described control chip is for receiving described second square-wave signal, and the 10th pin of described control chip is for exporting described pwm signal.
As shown in Figure 6, it is the circuit diagram of described LED drive circuit in one embodiment.
Described LED drive circuit 4 comprises the 18 resistance R18, the 19 resistance R19, the first triode Q1, the 20 resistance R20; The first end of described 18 resistance R18 is the input of described LED drive circuit 4; Second end of described 18 resistance R18 is connected with the base stage of described first triode Q1, and by described 19 resistance R19 ground connection; The grounded emitter of described first triode Q1; The output of the very described LED drive circuit 4 of current collection of described first triode Q1, is connected with direct voltage by described 20 resistance R20.Wherein, described first triode Q1 is for strengthening the drive current of LED.
As shown in Figure 7, it is the circuit diagram of described LED drive circuit in another embodiment.
Described LED drive circuit 4 comprises the 21 resistance R21, the second triode Q2, the 22 resistance R22, the 23 resistance R23, the 24 resistance R24, the 6th electric capacity C6, the 3rd triode Q3, the 4th triode Q4 and the 3rd diode D3; The first end of described 21 resistance R21 is the input of described LED drive circuit 4, and second end of described 21 resistance R21 is connected to the base stage of described second triode Q2; The grounded emitter of described second triode Q2, the first end of collector electrode and described 22 resistance R22, the first end of described 23 resistance R23 and the first end of described 24 resistance R24 are connected; The second end ground connection of described 22 resistance R22; Second end of described 23 resistance R23 is connected with the base stage of the base stage of described 3rd triode Q3, described 4th diode, and by described 6th electric capacity C6 ground connection; Second end of described 24 resistance R24 is connected with direct voltage; The positive pole of described 3rd diode D3 is connected with direct voltage, and negative pole is connected with the collector electrode of described 4th triode Q4; The emitter of described 4th triode Q4 is connected, as described LED with the emitter of described 3rd triode Q3
The output of drive circuit; The grounded collector of described 3rd triode Q3; The polarity of described 3rd triode Q3 and described 4th triode Q4 is contrary.Wherein, described second triode Q2 is for strengthening driving force, and what its collector electrode exported is also pwm signal.The RC filter circuit that pwm signal forms through the 23 resistance R23 and the 6th electric capacity C6 converts analog voltage to, driving voltage Vout=(VH-VL) α, VH is the maximum voltage of pwm signal, and VL is the minimum voltage of pwm signal, and α is the duty ratio of PWM ripple.Therefore pwm signal can be converted to the analog signal be directly proportional to duty ratio.3rd triode Q3 and the 4th triode Q4 forms push-pull circuit, strengthens driving force further.
The operation principle of the LED light adjusting circuit that the embodiment of the present invention provides is as follows:
1, when not needing to carry out light modulation, light modulation setup unit control CTL1 and CTL2 is in low level, and dim signal Lout is sinusoidal wave.
2, when needs increase brightness, be high level by light modulation setup unit control CTL2, control CTL1 is low level, described dim signal is the waveform that sine wave cuts away positive half wave, described first square-wave signal output low level, described second square wave signal output frequency is the square wave of 50HZ, and described pwm control circuit 3 according to detecting that number that the first square-wave signal lacks improves the duty ratio of pwm signal, thus increases the brightness of LED.
3, when needs reduce brightness, be low level by light modulation setup unit control CTL2, control CTL1 is high level, described dim signal is the waveform that sine wave cuts away negative half-wave, described second square-wave signal output low level, described first square wave signal output frequency is the square wave of 50HZ, and described pwm control circuit 3 according to detecting that number that the second square-wave signal lacks reduces the duty ratio of pwm signal, thus reduces the brightness of LED.
4, when the duty ratio of pwm signal reaches maximum (100%), continue to take the operation increasing brightness also can not change, with should the duty ratio of pwm signal reach minimum time, the operation continuing to take to reduce brightness also can not change.
5, when being increased to suitable brightness, the first dimmer switch S2 closes automatically, thus the brightness keeping LED present, in like manner, when reducing to suitable brightness, the second dimmer switch S3 closes automatically, thus the brightness keeping LED present.
The beneficial effect of the LED light adjusting circuit that the embodiment of the present invention provides is as follows: produce the copped wave of circuit 1 pair of live wire signal to produce dim signal by dim signal, and produce two-way square-wave signal respectively by dim signal change-over circuit 2, pwm control circuit 3 controls the duty ratio of pwm signal according to described two-way square-wave signal, thus changes the brightness of LED.Adopt single live wire mode to control LED illumination lamp brightness, without the need to remote controller, without the need to control line, also again need not lay power line, can realize the alternative upgrading of general lighting lamp, cost is low, and jamproof ability is strong.
One of ordinary skill in the art will appreciate that all or part of flow process realized in above-described embodiment method, that the hardware that can carry out instruction relevant by computer program has come, described program can be stored in a computer read/write memory medium, this program, when performing, can comprise the flow process of the embodiment as above-mentioned each side method.Wherein, described storage medium can be magnetic disc, CD, read-only store-memory body (Read-Only Memory, ROM) or random store-memory body (Random Access Memory, RAM) etc.
The above is the preferred embodiment of the present invention; it should be pointed out that for those skilled in the art, under the premise without departing from the principles of the invention; can also make some improvements and modifications, these improvements and modifications are also considered as protection scope of the present invention.
Claims (10)
1. a LED light adjusting circuit, is characterized in that, comprises dim signal and produces circuit, dim signal change-over circuit, pwm control circuit and LED drive circuit;
Described dim signal produces circuit and comprises light modulation setup unit, mains switch, the first optocoupler, the first controllable silicon, the first pull-up resistor, the first diode, the second pull-up resistor, the second optocoupler, the second controllable silicon, the first divider resistance, the second diode and the second divider resistance, and has live wire signal input part, dim signal output, the first control signal input and the second control signal input; The first end of described mains switch connects described live wire signal input part; The first input end of described first optocoupler is connected with direct voltage by described first pull-up resistor, and the second input of described first optocoupler is connected with described first control signal input; First output of described first optocoupler is connected with the negative pole of described first diode, and the second output of described first optocoupler controls pole with described first silicon controlled and is connected; Described first silicon controlled negative electrode is connected with the second end of described mains switch; Described first silicon controlled anode is connected with described dim signal output, and is connected with the positive pole of described first diode by described first divider resistance; The first input end of described second optocoupler is connected with direct voltage by described second pull-up resistor, and the second input of described second optocoupler is connected with described second control signal input; First output of described second optocoupler is connected with the negative pole of described second diode, and the second output of described second optocoupler controls pole with described second silicon controlled and is connected; Described second silicon controlled anode is connected with the second end of described mains switch, and is connected with the positive pole of described first diode by described second divider resistance; Described second silicon controlled negative electrode is connected with described dim signal output;
Described light modulation setup unit is for controlling the level of described first control signal input or described second control signal input;
Described dim signal change-over circuit for receiving the dim signal of neutral signal and the output of described dim signal generation circuit, and produces the first square-wave signal and the second square-wave signal according to described neutral signal and described dim signal;
Described pwm control circuit is used for according to described first square-wave signal and described second square-wave signal, adjusts the duty ratio of pwm signal and outputs to described LED drive circuit; Wherein, the square wave number that described pwm control circuit lacks for detecting described first square-wave signal, and the duty ratio improving described PWM ripple according to the square wave number that described first square-wave signal lacks; Described pwm control circuit also for detecting the square wave number that described second square-wave signal lacks, and reduces the duty ratio of described PWM ripple according to the square wave number that described second square-wave signal lacks;
Described LED drive circuit is used for driving described LED luminous according to described pwm signal.
2. LED light adjusting circuit as claimed in claim 1, it is characterized in that, described dim signal change-over circuit comprises the first resistance, the second resistance, the 3rd optocoupler, the 4th optocoupler, the 3rd resistance, the 4th resistance, the 5th resistance, the 6th resistance, the 7th resistance, the first electric capacity, the second electric capacity, the first inverter and the second inverter; The first end of described first resistance is for receiving described dim signal; Second end of described first resistance is connected with the first input end of described 3rd optocoupler, and is connected with the second input of described 4th optocoupler; The first end of described second resistance is for receiving neutral signal; Second end of described second resistance is connected with the first input end of described 4th optocoupler, and is connected with the second input of described 3rd optocoupler;
First output of described 3rd optocoupler connects direct voltage by described 3rd resistance, and the second output of described 3rd optocoupler is by described 4th grounding through resistance; The first end of described 5th resistance is connected with the second output of described 3rd optocoupler, and the second end of described 5th resistance is connected with the input of described first inverter, and by described first capacity earth; The output of described first inverter exports described first square-wave signal;
First output of described 4th optocoupler connects direct voltage by described 6th resistance, and the second output of described 4th optocoupler is by described 7th grounding through resistance; The first end of described 8th resistance is connected with the second output of described 4th optocoupler, and the second end of described 8th resistance is connected with the input of described second inverter, and by described second capacity earth; The output of described second inverter exports described second square-wave signal.
3. LED light adjusting circuit as claimed in claim 1, is characterized in that,
Described dim signal change-over circuit comprises the first low pass active filter circuit, a RC filter circuit, the first voltage follower circuit, the first bleeder circuit, the first comparison circuit, the second low pass active filter circuit, the 2nd RC filter circuit, the second voltage follower circuit, the second bleeder circuit and the second comparison circuit;
The input of described first low pass active filter circuit is for receiving described dim signal, and the output of described first low pass active filter circuit is connected to the first input end of described first comparison circuit successively by a described RC filter circuit and the first voltage follower circuit; The first input end of described first comparison circuit is connected to the second input of described second comparison circuit by described first bleeder circuit; The output of described first comparison circuit exports described first square-wave signal;
The input of described second low pass active filter circuit is for receiving described neutral signal, and the output of described second low pass active filter circuit is connected to the first input end of described second comparison circuit successively by described 2nd RC filter circuit and the second voltage follower circuit; The first input end of described second comparison circuit is connected to the second input of described first comparison circuit by described second bleeder circuit; The output of described second comparison circuit exports described second square-wave signal.
4. LED light adjusting circuit as claimed in claim 3, is characterized in that,
Described first low pass active filter circuit comprises the first resistance, the second resistance, the first electric capacity, the first operational amplifier and the 3rd resistance; The first end of described first resistance is the input of described first low pass active circuit, and the second end of described first resistance is by described second grounding through resistance; Described first electric capacity and described second resistor coupled in parallel; Second end of described first resistance is connected with the normal phase input end of described first operational amplifier; The two ends of described 3rd resistance connect inverting input and the output of described first operational amplifier respectively; The output of described first operational amplifier is the output of described first low pass active filter circuit;
Described second low pass active filter circuit comprises the 4th resistance, the 5th resistance, the second electric capacity, the second operational amplifier and the 6th resistance; The first end of described 4th resistance is the input of described second low pass active circuit, and the second end of described 4th resistance is by described 5th grounding through resistance; Described second electric capacity and described 5th resistor coupled in parallel; Second end of described 4th resistance is connected with the normal phase input end of described second operational amplifier; The two ends of described 6th resistance connect inverting input and the output of described second operational amplifier respectively; The output of described second operational amplifier is the output of described second low pass active filter circuit.
5. LED light adjusting circuit as claimed in claim 4, is characterized in that,
A described RC filter circuit comprises the 7th resistance and the 3rd electric capacity; The first end of described 7th resistance is connected with the output of described first low pass active filter circuit, and the second end of described 7th resistance is by described 3rd capacity earth; The output of described 7th resistance is the output of a described RC filter circuit;
Described 2nd RC filter circuit comprises the 8th resistance and the 4th electric capacity; The first end of described 8th resistance is connected with the output of described second low pass active filter circuit, and the second end of described 8th resistance is by described 4th capacity earth; The output of described 8th resistance is the output of described 2nd RC filter circuit.
6. LED light adjusting circuit as claimed in claim 5, is characterized in that,
Described first voltage follower circuit comprises the 3rd operational amplifier and the 9th resistance; The normal phase input end of described 3rd operational amplifier is the input of described first voltage follower circuit, the output of described 3rd operational amplifier is the output of described first voltage follower circuit, and the two ends of described 9th resistance connect inverting input and the output of described 3rd operational amplifier respectively;
Described second voltage follower circuit comprises four-operational amplifier and the tenth resistance; The normal phase input end of described four-operational amplifier is the input of described second voltage follower circuit, the output of described four-operational amplifier is the output of described second voltage follower circuit, and the two ends of described tenth resistance connect inverting input and the output of described four-operational amplifier respectively.
7. LED light adjusting circuit as claimed in claim 6, it is characterized in that, described first bleeder circuit comprises the 11 resistance and the 12 resistance; The first end of described 11 resistance is the input of described first bleeder circuit, and the second end of described 11 resistance is the output of described first bleeder circuit; Second end of described 11 resistance is by described 12 grounding through resistance;
Described second bleeder circuit comprises the 13 resistance and the 14 resistance; The first end of described 13 resistance is the input of described second bleeder circuit, and the second end of described 13 resistance is the output of described second bleeder circuit; Second end of described 13 resistance is by described 14 grounding through resistance.
8. LED light adjusting circuit as claimed in claim 7, is characterized in that,
Described first comparison circuit comprises the 5th operational amplifier and the 15 resistance; The inverting input of described 5th operational amplifier is the first input end of described first comparison circuit, the normal phase input end of described 5th operational amplifier is the second input of described first comparison circuit, the output of described 5th operational amplifier is the output of described first comparison circuit, and the two ends of described 15 resistance connect normal phase input end and the output of described 3rd operational amplifier respectively;
Described second comparison circuit comprises the 6th operational amplifier and the 16 resistance; The inverting input of described 6th operational amplifier is the first input end of described second comparison circuit, the normal phase input end of described 6th operational amplifier is the second input of described second comparison circuit, the output of described 6th operational amplifier is the output of described second comparison circuit, and the two ends of described 16 resistance connect normal phase input end and the output of described 6th operational amplifier respectively.
9. LED light adjusting circuit as claimed in claim 1, it is characterized in that, described LED drive circuit comprises the 18 resistance, the 19 resistance, the first triode, the 20 resistance; The first end of described 18 resistance is the input of described LED drive circuit; Second end of described 18 resistance is connected with the base stage of described first triode, and by described 19 grounding through resistance; The grounded emitter of described first triode; The output of the very described LED drive circuit of current collection of described first triode, is connected with direct voltage by described 20 resistance.
10. LED light adjusting circuit as claimed in claim 1, it is characterized in that, described LED drive circuit comprises the 21 resistance, the second triode, the 22 resistance, the 23 resistance, the 24 resistance, the 6th electric capacity, the 3rd triode, the 4th triode and the 3rd diode; The first end of described 21 resistance is the input of described LED drive circuit, and the second end of described 21 resistance is connected to the base stage of described second triode; The grounded emitter of described second triode, the first end of collector electrode and described 22 resistance, the first end of described 23 resistance and the first end of described 24 resistance are connected; Second end ground connection of described 22 resistance; Second end of described 23 resistance is connected with the base stage of the base stage of described 3rd triode, described 4th diode, and by described 6th capacity earth; Second end of described 24 resistance is connected with direct voltage; The positive pole of described 3rd diode is connected with direct voltage, and negative pole is connected with the collector electrode of described 4th triode; The emitter of described 4th triode is connected, as the output of described LED drive circuit with the emitter of described 3rd triode; The grounded collector of described 3rd triode; The polarity of described 3rd triode and described 4th triode is contrary.
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