CN101360374A - Driving circuit of light emitting diode unit - Google Patents

Abstract

A driving circuit of a light emitting diode unit comprises an isolated power supply conversion unit and a plurality of light emitting diode units. The isolated power conversion unit is provided with a plurality of output ends, receives an alternating current power supply and outputs a driving signal from each output end. The light emitting diode units are respectively electrically connected with the output ends and act according to the driving signals. The invention can simultaneously drive a plurality of groups of light emitting diode units and can improve the electric energy conversion efficiency.

Description

The driving circuit of the LED unit

technical field

The invention relates to a driving circuit of a light emitting unit, in particular to a driving circuit of a light emitting diode unit.

Background technique

Compared with general light sources (such as light bulbs or lamp tubes), light-emitting diodes (LEDs) have the advantages of long life, low power consumption, and small size, and because the technology of light-emitting diodes is becoming more and more The more mature, the application of light-emitting diodes has gradually appeared in indicator lights, backlight modules and even lighting equipment.

In order to take into account the requirements of driving characteristics and comply with electrical safety regulations, the power supply architecture used by general LEDs is divided into the AC/DC conversion circuit of the front stage and the LED drive circuit of the subsequent stage. Please refer to FIG. 1, taking an LED backlight module 1 as an example, it includes an AC/DC converter 11 with isolation function, multiple DC/DC converters 12a-12n and multiple groups of LED units 13a-13n . Wherein, each DC/DC converter 12a-12n is electrically connected to the corresponding LED unit 13a-13n.

The AC/DC converter 11 converts the AC power supply (mains power) 10 into a DC power output, and then each DC/DC converter 12a-12n converts it into a driving signal according to the DC power supply to drive the corresponding LED unit 13a-13n.

Based on the above, because LEDs that emit light of different colors require different driving signals, different LED units need to be driven by different DC/DC converters, so the cost is high and the circuit complexity will also increase. improve. In addition, due to the two-stage circuit structure of the AC/DC converter and the DC/DC converter, the power conversion efficiency will also be reduced due to the loss of each stage.

Therefore, how to provide a driving circuit for the LED unit so that it can simultaneously drive multiple sets of LED units and improve the power conversion efficiency is one of the current important issues.

In view of the above-mentioned defects in the existing drive circuit, the inventor actively researches and innovates based on years of rich practical experience and professional knowledge engaged in the design and manufacture of such products, and cooperates with the application of academic theory, in order to create a new type of structure. The driving circuit of the diode unit can improve the general existing driving circuit and make it more practical. Through continuous research, design, and after repeated trial samples and improvements, the present invention with practical value is finally created.

Contents of the invention

The main purpose of the present invention is to overcome the defects of the existing driving circuit and provide a driving circuit of a light emitting diode unit with a new structure. The technical problem to be solved is to enable it to drive multiple groups of light emitting diode units simultaneously and to Improve the efficiency of electric energy conversion, so that it is more suitable for practical use.

The purpose of the present invention and the solution to its technical problems are achieved by adopting the following technical solutions. A drive circuit for a light emitting diode unit proposed according to the present invention includes: an isolated power conversion unit receiving an AC power supply and having multiple output terminals, wherein each output terminal outputs a driving signal; and multiple light emitting diode units, They are respectively electrically connected with each output terminal, and act according to the driving signal. Here, the so-called action refers to the action of the light emitting diode unit emitting or stopping emitting light.

The purpose of the present invention and its technical problems can also be further realized by adopting the following technical measures.

The aforementioned driving circuit, wherein the isolated power conversion unit includes:

An isolation transformer has a primary side and a secondary side, wherein the output terminal is arranged on the secondary side, and the secondary side has a plurality of windings, and each winding corresponds to each output terminal; and

A rectifier is electrically connected with the primary side of the isolation transformer, and outputs a power signal to the isolation transformer according to the AC power supply.

In the aforementioned drive circuit, the rectifier is a half-bridge rectifier or a full-bridge rectifier.

In the aforementioned drive circuit, the power signal is a DC power signal.

In the aforementioned driving circuit, each LED unit includes at least one LED.

In the aforementioned drive circuit, the LED unit includes a red LED unit, a green LED unit, a blue LED unit or a white LED unit.

In the aforementioned drive circuit, the LED unit is a light bar type LED unit.

The aforementioned driving circuit further includes:

An energy adjustment unit, having a plurality of switching elements, each switching element is electrically connected to each light emitting diode unit;

a control unit electrically connected to the energy conditioning unit and the isolated power conversion unit, the control unit generates at least one energy conditioning signal to the energy conditioning unit; and

A feedback control unit is electrically connected with the energy adjustment unit and the control unit respectively, and generates a feedback signal according to the energy adjustment signal to output to the control unit.

The aforementioned drive circuit, wherein the control unit includes:

a light mixing controller, electrically connected to the energy adjustment unit, and generates the energy adjustment signal to the energy adjustment unit;

a switching element electrically connected to the isolated power conversion unit; and

A pulse width modulation signal generator generates at least one pulse width modulation signal to control the switching element.

In the aforementioned driving circuit, the light-emitting start time and/or the light-emitting end time of each LED unit are different.

The aforementioned drive circuit further includes a power factor correction unit electrically connected to the isolated power conversion unit, and outputs a power signal to the isolated power conversion unit according to an AC signal.

With the above technical solutions, the driving circuit of the LED unit of the present invention has at least the following advantages: The driving circuit of the LED unit of the present invention uses an isolated power conversion unit with multiple output terminals to drive the LED unit. The single-stage architecture can reduce power consumption to improve the working efficiency of the driving circuit, and further reduce heat generation.

To sum up, the novel driving circuit of the light emitting diode unit of the present invention can simultaneously drive multiple sets of light emitting diode units and can improve the power conversion efficiency. The present invention has the above-mentioned many advantages and practical value, and it has great improvement no matter in structure or function, has remarkable progress in technology, and has produced easy-to-use and practical effects, and has more advantages than the existing drive circuit. The improved efficacy is more suitable for practical use and has wide application value in the industry. It is a novel, progressive and practical new design.

The above description is only an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention, it can be implemented according to the contents of the description, and in order to make the above and other purposes, features and advantages of the present invention more obvious and understandable , the following preferred embodiments are specifically cited below, and are described in detail as follows in conjunction with the accompanying drawings.

Description of drawings

FIG. 1 is a system block diagram of a conventional LED backlight module.

FIG. 2 is a structural block diagram of a driving circuit of an LED unit according to a preferred embodiment of the present invention.

FIG. 3 is another structural block diagram of a driving circuit of an LED unit according to a preferred embodiment of the present invention.

FIG. 4 is a schematic circuit diagram of a driving circuit of an LED unit according to a preferred embodiment of the present invention.

FIG. 5 is a schematic diagram of a driving circuit of a light emitting diode unit in a preferred embodiment of the present invention, wherein the energy of the light emitting diode unit is controlled.

FIG. 6 is a structural block diagram of a driving circuit of an LED unit according to another preferred embodiment of the present invention.

1: Backlight module 10, 20: AC power supply

11: AC/DC Converter 12a-12n: DC/DC Converter

13a-13n, 22 ₁ -22 _N : LED unit

2: The drive circuit of the LED unit

21: Isolated power conversion unit 211: Isolated transformer

212: Rectifier 23: Energy regulation unit

24: Control unit 241, Q ₁ -Q _N : Switching elements

242: Pulse Width Modulation Signal Generator 243: Light Mixing Controller

25: Feedback control unit 26: Power factor correction unit

O ₁ -O _N : output terminal

Detailed ways

In order to further explain the technical means and effects of the present invention to achieve the intended purpose of the invention, the specific implementation, structure, characteristics and details of the driving circuit of the light emitting diode unit proposed according to the present invention will be described below in conjunction with the accompanying drawings and preferred embodiments. Its effect is described in detail below.

Please refer to FIG. 2 , the driving circuit 2 of the LED unit according to the preferred embodiment of the present invention includes an isolated power conversion unit 21 and a plurality of LED units 22 ₁ -22 _N .

The isolated power conversion unit 21 has a plurality of output terminals O _{1 -ON} , and the output terminals O _{1 -ON} are electrically connected to corresponding LED units 22 ₁ -22 _N . And the isolated power conversion unit 21 receives an AC power source 20, and outputs a driving signal from each output terminal O _{1 -ON} to drive the LED units 22 _{1 -22N} to emit light. In this embodiment, the structure of the isolated power conversion unit 21 can be flyback (Flyback), forward (Forward), half bridge (Half Bridge), full bridge (Full Bridge) or push-pull (Push-pull) -Pull) etc. can be applied to any architecture of AC/DC converters. In addition, the LED units 22 ₁ -22 _N can be red, green, blue or white LED units 22 ₁ -22 _N , and each LED unit 22 ₁ -22 _N can have at least one LED. And when the LED unit has a plurality of LEDs, it can be a light bar type LED unit.

Please refer to FIG. 3 again, the isolated power conversion unit 21 includes an isolated transformer 211 and a rectifier 212 . The rectifier 212 can be a half-bridge rectifier or a full-bridge rectifier, which outputs a power signal (DC power) to the isolation transformer 211 according to the AC power (mains) 20 . The isolation transformer 211 has a primary side and a secondary side, and has a plurality of windings (coils) on the secondary side, and the windings respectively correspond to the output terminals O _{1 -ON} .

In this embodiment, since the LED units of different colors require different driving signals, the windings may have different numbers of turns to convert the power signal into the required driving signal to drive the LED units. 22 ₁ -22 _N emits light.

Please refer to FIG. 4 again, the drive circuit 2 of this embodiment further includes an energy regulation unit 23 , a control unit 24 and a feedback control unit 25 . Wherein, the energy adjustment unit 23 has a plurality of switching elements Q ₁ -Q _N , and each switching element Q ₁ -Q _N is electrically connected to the corresponding light emitting diode unit 22 ₁ -22 _N , and the switching elements Q ₁ - The turn on and turn off of Q _N together with the driving signal control the luminance of each LED unit 22 ₁ -22 _N.

The control unit 24 is electrically connected to the energy adjustment unit 23 and the isolated power conversion unit 21 respectively, and the control unit 24 includes a switch element 241 , a pulse width modulation signal generator 242 and a light mixing controller 243 . The switching element 241 is electrically connected to the primary side of the PWM signal generator 242 and the isolation transformer 211 respectively.

The pulse width modulation signal generator 242 generates a pulse width modulation signal to control the switch element 241 , thereby adjusting the total energy of the driving signal output from the secondary side of the isolation transformer 211 . The light mixing controller 243 generates at least one energy adjustment signal to each switch element Q ₁ -Q _N of the energy adjustment unit 23 in time sequence. The energy regulation signal can be a pulse width modulation (PWM) signal, and by controlling the duty cycle of the PWM signal, the luminance of the LED units 22 ₁ - 22 _N can be controlled.

The feedback control unit 25 is electrically connected to the energy regulation unit 23 and the control unit 24 respectively, and generates a feedback signal according to the energy regulation signal, and outputs it to the control unit 24 . The control unit 24 can control the duty cycle or the amplitude of the PWM signal according to the feedback signal to adjust the total energy of the driving signal. However, since there are many methods of feedback control, such as maximum current feedback control, average current feedback control, etc., each of which has a different design method, this is only an example and not intended to limit the status of the feedback control.

It should be noted that in this embodiment, circuits such as filter circuits or anti-backflow protection circuits (not shown in the figure) may also exist between the secondary side of the isolation transformer 211 and the LED units 22 ₁ -22 _N. It can be freely designed in the drive circuit according to the requirements.

In addition, please refer to FIG. 5. In this embodiment, when the light emitting diode units are red, green and blue light emitting diode units, in order to achieve the light mixing effect, the light mixing controller 243 will control the switching elements Q ₁ -Q _N The turn-on time of each color can be controlled. In some applications, the light-emitting start times of the LED units 22 ₁ - 22 _N may be the same, however, this may cause excessive ripple current. Therefore, the light mixing controller 243 can be designed to control the switching elements Q ₁ -Q _N in a synchronous manner, which means that the red, green and blue light emitting diode units start to emit light at different times and end at the same time. different. As shown in FIG. 5 , for example, t1-t6 is the lighting time of the red LED unit, t2-t5 is the lighting time of the green LED unit, and t3-t4 is the lighting time of the blue LED unit. In this way, the switch units controlling the red, green and blue light-emitting diode units are cut in at different times, so that the ripple current can be reduced.

As shown in FIG. 6, in addition to the above structure, another drive circuit 2' may include a power factor correction (power factor correction, PFC) unit 26, which is electrically connected to the AC power supply 20 and the isolated power conversion unit 21 to correct the power factor in the drive circuit 2' to have a better power factor.

In summary, according to the driving circuit of the LED unit of the present invention, the LED unit is driven by an isolated power conversion unit with multiple output terminals. The single-stage architecture can reduce power consumption to improve the working efficiency of the driving circuit, and further reduce heat generation.

The above description is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this field Those skilled in the art, without departing from the scope of the technical solution of the present invention, can use the technical content disclosed above to make some changes or modify equivalent embodiments with equivalent changes, but all the content that does not depart from the technical solution of the present invention, according to the present invention Any simple modifications, equivalent changes and modifications made to the above embodiments by the technical essence still belong to the scope of the technical solutions of the present invention.

Claims (11)

1, a kind of driving loop of light emitting diode is characterized in that comprising:

One isolated supplies converting unit receives an AC power and has a plurality of outputs, and wherein each output is exported a drive signal; And

A plurality of light emitting diodes electrically connect with each output respectively, and move according to this drive signal.

2, driving according to claim 1 loop is characterized in that wherein said isolated supplies converting unit comprises:

One isolated form transformer has primary side and secondary side, and wherein said output is arranged at this secondary side, and this secondary side has a plurality of windings, respectively corresponding each output of each winding; And

One rectifier electrically connects with this primary side of this isolated form transformer, and exports a power signal to this isolated form transformer according to this AC power.

3, driving according to claim 2 loop is characterized in that wherein said rectifier is half bridge rectifier or a full bridge rectifier.

4, driving according to claim 2 loop is characterized in that wherein said power signal is a direct current power supply signal.

5, driving according to claim 1 loop is characterized in that wherein each light emitting diode comprises at least one light-emitting diode.

6, driving according to claim 1 loop is characterized in that wherein said light emitting diode comprises a red light emitting diodes unit, a green LED unit, a blue LED unit or a white light-emitting diode unit.

7, driving according to claim 1 loop is characterized in that wherein said light emitting diode is the light emitting diode of an optical wand pattern.

8, driving according to claim 1 loop is characterized in that it more comprises:

One energy adjustment unit has a plurality of switch elements, and each switch element and each light emitting diode electrically connect;

One control unit electrically connects with this energy adjustment unit and this isolated supplies converting unit respectively, and this control unit produces at least one energy adjustment signal to this energy adjustment unit; And

One back coupling control unit electrically connects with this energy adjustment unit and this control unit respectively, and produces a feedback signal according to this energy adjustment signal, it is exported to this control unit.

9, driving according to claim 8 loop is characterized in that wherein said control unit comprises:

One mixed light controller electrically connects with this energy adjustment unit, and produces this energy adjustment signal to this energy adjustment unit;

One switch element electrically connects with this isolated supplies converting unit; And

One pulse-width modulation signal generator produces at least one pulse-width modulation signal to control this switch element.

10, driving according to claim 1 loop is characterized in that wherein the luminous zero-time and/or the luminous concluding time of each light emitting diode are different.

11, driving according to claim 1 loop is characterized in that it more comprises a power factor correction unit, and itself and isolated supplies converting unit electrically connect, and exchanges telecommunication and export a power signal to this isolated supplies converting unit according to one.

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