CN101754538B

CN101754538B - Adjustable photocontrol circuit of LED (light-emitting diode) lamp

Info

Publication number: CN101754538B
Application number: CN 201010106383
Authority: CN
Inventors: 肖俊承; 熊川高
Original assignee: Eaglerise Electric and Electronic China Co Ltd
Current assignee: Foshan Igor Electronics Co Ltd
Priority date: 2010-02-01
Filing date: 2010-02-01
Publication date: 2012-12-12
Anticipated expiration: 2030-02-01
Also published as: CN101754538A

Abstract

The invention discloses an adjustable photocontrol circuit of an LED (light-emitting diode) lamp, which comprises a power supply conversion circuit capable of connecting an LED lamp load and a PWM (pulse width modulation) control circuit and is characterized in that the power supply conversion circuit comprises a voltage transformation circuit, a rectification filter circuit and an LED load control circuit, the output end of the PWM control circuit is sequentially connected with a diode D3 and a resister R3 in series, and the output end of the resister R3 is connected with a reference control point (A) of the LED load control circuit. The standard control point (A) is an anodic control end of an opticalcoupler, a control end of a reference voltage source or a control end of a comparator. The PWM control circuit is powered by an auxiliary power supply or connected with the output end of the power supply conversion circuit. Because of the advantages, The invention can be applied to a similar laden control circuit of the LED lamp and the like.

Description

The tunable optical control circuit of LED lamp

Technical field

The present invention relates to LED lamp lighting control technique field, design the design of the tunable optical control circuit of LED lamp especially.

Background technology

Common Dimmable LED circuit has following two kinds of forms:

First kind of scheme such as Chinese patent number are 200620047055.9, and name is called that " pulse width type energy-saving LED lamp dimmer " disclosed, and the turnable pulse width that adopts the timer integrated circuit of one type of NE555 to produce is regulated, and connects the phase-cut dimming device at input and carries out light modulation; Sort circuit is to realize dimming function with pulse current, does not cause people's visual institute to be discovered though pulse frequency is very high, and is harmful to the useful life and the job stability of light-emitting diode, simultaneously electrical network had certain pollution.

Second kind of scheme such as Chinese patent number are 200820085623.3, name is called " Dimmable LED illuminating lamp ", and is as shown in Figure 1, have disclosed the circuit that the two-stage Switching Power Supply realizes dimming function.This kind method for designing has overcome the defective of first kind of circuit, employing be two-stage Switching Power Supply pattern, promptly earlier high line voltage is reduced to a dc voltage value of design in advance through an AC/DC Switching Power Supply; Commonly used have 5V, 12V, 24V; 48V...... Deng not limitting, then through a DC/DC Buck drives LED, in this Buck circuit; Current trend has multiple light modulation IC chip, all is to utilize PWM port that a pwm signal drives special-purpose dimming LED (Light Emitting Diode) IC to realize light modulation.The constant-current source LED's that chip outputs to that sort circuit uses is constant current rather than pulse; Well overcome the defective of first kind of traditional light adjusting circuit; Can realize good dimming effect; But because have two-stage circuit, reduced the service efficiency of power supply virtually, be not inconsistent with the energy saving direction of present implementation.

Summary of the invention

In view of the drawback of above two kinds of existing LED light adjusting circuits, the special a kind of new LED tunable optical mode-one-level circuit design that proposes realizes dimming function.

A kind of tunable optical control circuit of LED lamp comprises the power-switching circuit and the pwm control circuit that can connect the LED lamp load; It is characterized in that; Said power-switching circuit comprises transforming circuit, current rectifying and wave filtering circuit and LED load control circuit; The output of said pwm control circuit is in sequential series to have diode D3 and resistance R 3; The output of said resistance R 3 connects the benchmark control point A of said LED load control circuit, and said benchmark control point A is the anodic control end of optocoupler, the control end of reference voltage source or the control end of comparator.

Secondly, the power supply of said pwm circuit can also can be supplied power by the output of power-switching circuit by independently accessory power supply power supply.

According to above-mentioned technical scheme, said power-switching circuit is realized the AC/DC of input civil power is changed, also realizes the control to the LED load.Control basic point at AC/DC one-level power-switching circuit connects special-purpose pwm control circuit, and said pwm control circuit is made in its feedback control loop that participates in the LED driving power, utilizes the variation of duty ratio, realizes the purpose to the LED light modulation.Remedied the defective of existing two kinds of traditional light adjusting circuits so simultaneously, improved product efficiency greatly, reached desirable energy-saving effect, more traditional LED dimming mode most effectively improves 10%.

Because the design has above-mentioned advantage, can be applied in the control circuit of similar load such as LED lamp.

Description of drawings

Fig. 1 is the block diagram of the control procedure of prior art;

Fig. 2 is a block diagram of using the control procedure of technical scheme of the present invention;

Fig. 3 is the line construction sketch map of said pwm control circuit;

Fig. 4 is first concrete control circuit sketch map of using the said power-switching circuit of technical scheme of the present invention;

Fig. 5 is the SL71061 type constant voltage of power-switching circuit described in Fig. 4 and the conspectus of constant current control chip;

Fig. 6 is second concrete control circuit sketch map using the said power-switching circuit of technical scheme of the present invention;

Fig. 7 is the 3rd a concrete control circuit sketch map using the said power-switching circuit of technical scheme of the present invention;

Fig. 8 is the 4th a concrete control circuit sketch map using the said power-switching circuit of technical scheme of the present invention.

Embodiment:

Below in conjunction with accompanying drawing the embodiment of using the present invention program is explained.

As shown in Figure 2, said power-switching circuit 1 completion city voltage converts into and directly is connected load LED lamp after safe voltage, filtering and constant-current constant-voltage circuit are handled.Special constant-current IC chip no longer is set in the said like this power-switching circuit 1, but replaces with common constant-current constant-voltage circuit.Connect the output of said pwm control circuit at the feedback basic point of LED control circuit, the duty ratio of coming direct conditioning signal through the output pulse width of regulating said pwm control circuit, thus realize Current Control to load LED lamp, and then regulate the brightness of LED lamp.

As shown in Figure 3, be the line construction sketch map of said pwm control circuit.The power supply of wherein said pwm circuit can also can be supplied power by the output of power-switching circuit by independently accessory power supply power supply.Output at 555 circuit of routine has increased diode D3 and R3.When pwm control circuit is connected with the FEEDBACK CONTROL end of common LED drive circuit with resistance R 3 through diode D3; Regulator potentiometer W; The duty ratio of output is changed; Thereby make the feedback signal of common LED drive circuit controlled,, realize the purpose of light modulation to regulate the output of LED driving power.

A. as potentiometer W during to lower slider, the Vcc power supply is through R1, the top of potentiometer W, and D2 increased to the time of C1 charging, and duty ratio increases (increase of output voltage effective value);

B. when potentiometer W upwards slided, the Vcc power supply passed through R1, the top of potentiometer W, and D2 shortened to the time of C1 charging, and duty ratio reduces (the output voltage effective value reduces);

Therefore, typical circuit shown in Figure 3 can effectively be realized the variation of duty ratio, the just variation of control output voltage effective value.3 outputs of resistance R described in Fig. 3 are linked to each other with A point among Fig. 4, Fig. 6, Fig. 7 or Fig. 8; After ground wire is communicated with among two figure; The variation of circuit output duty cycle shown in Figure 3; Just can control chart 4, the circuit design output among Fig. 6, Fig. 7 or Fig. 8, thereby just can be easily in the common LED drive circuit increase to the dimming function of LED load.Concrete control relation is:

When a. the output duty cycle of pwm control circuit described in Fig. 3 increases (increase of output voltage effective value), the deepening of LED lamp;

When b. the output duty cycle of pwm control circuit described in Fig. 3 reduces (the output voltage effective value reduces), the deepening of LED lamp;

In foregoing circuit, the power supply VCC of said PWM can take from the output of circuit among Fig. 4, Fig. 6, Fig. 7 or Fig. 8, also can use independent current source to carry out.

As shown in Figure 5, chip SL71061 is a kind of constant voltage and constant current control chip, and this chip is the crossing current constant voltage common chip of control circuit shown in Figure 4.Can find out that by this figure A point access point essence is the control end of comparator among Fig. 4.

Be illustrated in figure 4 as the basic light modulation process of light modulation circuit, a kind of typical feedback control circuit of Switching Power Supply, its lower state is: load terminal voltage Uo descends, and causes the voltage U a at feedback reference point A place to rise; The voltage U a at feedback reference point A place rises; Then cause the chip SL71061DC pin voltage U ic-pin5 of place to descend, on optocoupler U2 luminous tube, electric current I u2_diode rises; Cause the conducting of optocoupler U2 triode at last; Thereby, make the control duty ratio descend, thereby load terminal voltage Uo is descended for the FB pin of U1 provides a signal.The whole circulation process has effectively been controlled the variation of load end, realizes Steady-State Control.In case insert the adjusting control circuit that Fig. 2 frame of broken lines shows at feedback reference point A; Can regulate the voltage U a at feedback reference point A place through slide rheostat, achieve effective variation of voltage, can know according to the foregoing circuit change procedure; The variation of Ua can cause the variation of Uo, and is following basically:

W is when lower slider, and Ua rises, and then Uo descends, LED load deepening;

When W upwards slided, Ua descended, and then Uo rises, and the LED load brightens;

As shown in Figure 6, the benchmark control A point in this embodiment is the anodic control end of optocoupler;

As shown in Figure 7, the benchmark control A point in this embodiment is the control end of reference voltage source;

As shown in Figure 8, the benchmark control A point essence in this embodiment is the control end of comparator.

Claims

1. the tunable optical control circuit of a LED lamp comprises pwm control circuit and the power-switching circuit that is connected the LED lamp load; It is characterized in that; Said power-switching circuit comprises transforming circuit, current rectifying and wave filtering circuit and LED load control circuit; The output of said pwm control circuit is in sequential series to have diode D3 and resistance R 3, and the output of said resistance R 3 connects the benchmark control point (A) of said LED load control circuit; Said benchmark control point (A) is the anodic control end of optocoupler, the control end of reference voltage source or the control end of comparator, and the input of said pwm control circuit is connected the output of said power-switching circuit; Said pwm control circuit is by independently accessory power supply power supply.