CN201639821U

CN201639821U - Dimming control circuit of LED lamp

Info

Publication number: CN201639821U
Application number: CN2010201090619U
Authority: CN
Inventors: 肖俊承; 熊川高
Original assignee: Foshan Eaglerise Electric & Electronic Co Ltd
Current assignee: Eaglerise Electric and Electronic China Co Ltd
Priority date: 2010-02-01
Filing date: 2010-02-01
Publication date: 2010-11-17
Anticipated expiration: 2020-02-01

Abstract

A dimming control circuit of an LED lamp comprises a power switching circuit connected with the load of the LED lamp, and a PWM control circuit, and is characterized in that the power switching 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 resistor R3 in series, and the output end of the resistor R3 is connected with a datum control point (A) of the LED load control circuit; and the reference control point (A) is the anode control end of an optical coupler, the control end of a reference voltage source or the control end of a comparator. The PWM control circuit is powered by an independent auxiliary power source or connected at the output end of the power switching circuit. Due to the advantages, the dimming control circuit can be applied in control circuits of similar loads, such as LED lamp and the like.

Description

The tunable optical control circuit of LED lamp

Technical field

The utility model relates to LED lamp lighting control technique field, designs 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 China Patent No. are 200620047055.9, and it is disclosed that name is called " pulse width type energy-saving LED lamp dimmer ", and the turnable pulse width that adopts the timer integrated circuit of NE555 one class 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 China Patent No. are 200820085623.3, name is called " Dimmable LED illuminating lamp ", 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, what adopt is two-stage Switching Power Supply pattern, promptly by an AC/DC Switching Power Supply high line voltage is reduced to a dc voltage value of design in advance earlier, using always has 5V, 12V, 24V, 48V...... Deng not limitting, then by a DC/DC Buck drives LED, in this Buck circuit, current trend has multiple light modulation IC chip, all is to utilize a pwm signal to drive the PWM port of 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, described power-switching circuit comprises transforming circuit, current rectifying and wave filtering circuit and LED load control circuit, the output of described pwm control circuit is in sequential series diode D3 and resistance R 3, the output of described resistance R 3 connects the benchmark control point A of described LED load control circuit, and described 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 described pwm circuit can also can be powered by the output of power-switching circuit by independently accessory power supply power supply.

According to above-mentioned technical scheme, described 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 described 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 solutions of the utility model;

Fig. 3 is the line construction schematic diagram of described pwm control circuit;

Fig. 4 is first concrete control circuit schematic diagram of using the described power-switching circuit of technical solutions of the utility model;

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 schematic diagram using the described power-switching circuit of technical solutions of the utility model;

Fig. 7 is the 3rd a concrete control circuit schematic diagram using the described power-switching circuit of technical solutions of the utility model;

Fig. 8 is the 4th a concrete control circuit schematic diagram using the described power-switching circuit of technical solutions of the utility model.

Embodiment:

Below in conjunction with accompanying drawing the embodiment of using the utility model scheme is illustrated.

As shown in Figure 2, described power-switching circuit 1 is finished and directly is connected load LED lamp after city's voltage is converted to safe voltage, filtering and constant-current constant-voltage circuit processing.Special constant-current IC chip no longer is set in the described like this power-switching circuit 1, but replaces with common constant-current constant-voltage circuit.Connect the output of described pwm control circuit at the feedback basic point of LED control circuit, the duty ratio of coming direct conditioning signal by the output pulse width of regulating described 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 schematic diagram of described pwm control circuit.The power supply of wherein said pwm circuit can also can be powered 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 by diode D3, regulator potentiometer W, the duty ratio of output is changed, thereby make the feedback signal of common LED drive circuit controlled, to regulate the output of LED driving power, realize the purpose of light modulation.

A. as potentiometer W during to lower slider, the Vcc power supply is by 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 described 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.By this figure as can be seen, 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 SL71061 DC 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 by slide rheostat, achieve effective variation of voltage, as can be known according to the foregoing circuit change procedure, the variation of Ua can cause the variation of Uo, and is as follows substantially:

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 control of the benchmark in this embodiment A point is the anodic control end of optocoupler;

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

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

Claims

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

2. the tunable optical control circuit of LED lamp according to claim 1 is characterized in that, described pwm control circuit is by independently accessory power supply power supply.

3. the tunable optical control circuit of LED lamp according to claim 1 is characterized in that, the input of described pwm control circuit is connected the output of described power-switching circuit.