A kind of interchange trailing type light adjusting circuit
Technical field
The utility model discloses a kind of light adjusting circuit, particularly a kind of interchange trailing type light adjusting circuit.
Background technology
Along with the development of LED Lighting Industry, LED has been widely used in lighting field as illuminating device.In the LED lighting circuit, usually need carry out light modulation to LED brightness, especially need light modulation to be carried out in LED brightness according to the size of AC-input voltage, common way is to adopt digital type light-adjusting circuit to realize in the industry at present, need to increase independent digital type light-adjusting circuit module, the control circuit of digital type light-adjusting circuit is loaded down with trivial details, the cost height, and easily produce the high-frequency electromagnetic wave interference.
Summary of the invention
Realize the cost height at the above-mentioned LED light adjusting circuit of mentioning of the prior art, the shortcoming of easy electromagnetic wave interference, the utility model provide a kind of new interchange trailing type light adjusting circuit, and it utilizes pure analog circuit that LED is carried out the trailing type light modulation, the realization circuit is simple, and cost is low.
The technical scheme that its technical problem that solves the utility model adopts is: a kind of interchange trailing type light adjusting circuit, light adjusting circuit comprises rectification filtering module, optocoupler, current/voltage modular converter and constant current control module, electric main input rectifying filtration module, the input optocoupler is elementary behind rectification filtering module, the secondary current/voltage modular converter that is connected to of optocoupler, convert the secondary current signal of optocoupler to voltage signal input constant current control module, regulate the brightness of LED lamp by constant current control module control output.
The technical scheme that its technical problem that solves the utility model adopts further comprises:
Described current/voltage modular converter comprises triode Q1, the base stage of triode Q1 connects+the 12V power supply with the secondary emitter that is connected triode Q1 of optocoupler, the collector electrode of triode Q1 is by resistance R 9 ground connection, and the collector electrode of triode Q1 is connected with the constant current control module by resistance R 5.
Described constant current control module adopts current comparator U1B, and the output of current/voltage modular converter is connected with the in-phase input end of current comparator U1B, and the inverting input of current comparator U1B is connected with reference current source.
Be connected with isolation diode D2 between described current/voltage modular converter and the constant current control module.
Be serially connected with resistance R 4 between described diode D2 and the constant current control module input, be serially connected with resistance R 8 between constant current control module input and the ground.
The beneficial effects of the utility model are: the utility model can be followed the height according to input ac voltage, thus the brightness of control LED lamp.The utility model circuit structure is simple, belongs to pure analog circuit, realizes that cost is low, the convenient realization, but also can realize high-pressure side electrified body and low-pressure side isolation, make control safer.
Below in conjunction with the drawings and specific embodiments the utility model is described further.
Description of drawings
Fig. 1 is the utility model circuit theory diagrams.
Fig. 2 is for using led drive circuit block diagram of the present utility model.
Embodiment
Present embodiment is the utility model preferred implementation, and other all its principles are identical with present embodiment or approximate with basic structure, all within the utility model protection range.
Please referring to accompanying drawing 2, led drive circuit generally includes power branch and light modulation branch road, common led drive circuit adopts electric main to power, its power branch becomes direct current after being mainly electric main input process EMC filtration module and rectification module, after boosting, direct current PFC booster circuit exports power tube to, power tube is by PWM resonance modules control turn-on and turn-off, PWM resonance modules feedback control signal is given the PFC control module, by the work of PFC control module control PFC booster circuit, the turn-on and turn-off of PWM resonance modules power controlling pipe, make power tube output square wave power signal, after the square wave power signal becomes low tension through the transformer transformation, through low-pressure side filter circuit rear drive LED lamp string, feed back to the PWM resonance modules through feedback module behind the electric current of electric current and voltage sampling module sampling low-pressure side filter circuit and the voltage signal, make the turn-on and turn-off of PWM resonance modules power controlling pipe.The utility model mainly makes improvements (being dotted portion in the accompanying drawing 1) to the light modulation branch road, please referring to accompanying drawing 1, the utility model mainly comprises rectification filtering module, optocoupler, current/voltage modular converter and constant current control module, in the present embodiment, rectification filtering module comprises diode D1 and capacitor C 1, electric main input rectifying filtration module, through 1 filtering becomes direct voltage through capacitor C again after the diode D1 rectification, input optocoupler U2's is elementary, the secondary current/voltage modular converter that is connected to of optocoupler U2, convert the secondary current signal of optocoupler U2 to voltage signal, in the present embodiment, the current/voltage modular converter comprises triode Q1, the base stage of triode Q1 connects+the 12V power supply with the secondary emitter that is connected triode Q1 of optocoupler U2, the collector electrode of triode Q1 is by resistance R 9 ground connection, the collector electrode of triode Q1 is connected with the constant current control module by resistance R 5, regulate the brightness of LED lamp by constant current control module control output, in the present embodiment, the constant current control module adopts current comparator U1B, the output of current/voltage modular converter is connected with the in-phase input end of current comparator U1B, the inverting input of current comparator U1B is connected with reference current source, be connected with isolation diode D2 between resistance R 5 and the current comparator U1B, be serially connected with resistance R 4 between diode D2 and the current comparator U1B, be serially connected with resistance R 8 between current comparator U1B in-phase input end and the ground.
The utility model in use, when electric main inserts, by becoming direct voltage after 1 filtering of process capacitor C again after the diode D1 rectification, export to the elementary of optocoupler U2, make its work for suitable bias voltage of optocoupler U2, according to flowing through varying in size of optocoupler U2 primary current, respective change also takes place in the secondary output of optocoupler U2, thereby control flows is crossed the size of the C-E junction electrode electric current of triode Q1, undertaken isolating through diode D2 again after the dividing potential drop by resistance R 5 and resistance R 9 then, and then compare by obtaining input in the same way and current reference source that a suitable voltage enters current comparator U1B after resistance R 4 and resistance R 8 dividing potential drops, the size of control output current, its output current is exported to electric current and voltage sampling module and PWM resonance modules simultaneously, realizes regulating the power of terminal LED lamp brightness.
The utility model can be followed the height according to input ac voltage, thus the brightness of control LED lamp.The utility model circuit structure is simple, realizes that cost is low, but also can realize high-pressure side electrified body and low-pressure side isolation, makes control safer.