KR20130013221A - (dimmer operation maintenance circuit for led illumination system - Google Patents

Abstract

PURPOSE: A dimmer operation maintenance circuit of an LED lighting system is provided to supply differential current between current in an LED and predetermined operation maintenance current to operation maintenance compensation current of a triac in a dimmer, thereby stabilizing an operation of the dimmer. CONSTITUTION: A dimmer(410) controls a conduction angle of a triac corresponding to a user request. A bridge diode rectification unit(420) rectifies AC power and supplies the AC power to driving power of an LED lighting device(430). The LED lighting device controls illumination by the conduction angle of the triac in the dimmer. The LED lighting device includes a first current detection unit(435), an error current operation unit(438), and a constant current device(439) for the dimmer. [Reference numerals] (410) Dimmer; (420) Bridge diode rectification unit; (431) Power supplying unit; (433) LED driving control unit; (434) Constant current device for LED; (436) Low-band filter; (437) Reference voltage generation unit; (438) Error current operation unit; (439) Constant current device for a dimmer

Description

 Dimmer Operation Maintenance Circuit of LED Lighting System {(DIMMER OPERATION MAINTENANCE CIRCUIT FOR LED ILLUMINATION SYSTEM}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving technique of an LED lighting apparatus, and more particularly, to a dimmer operating holding circuit of an LED lighting system adapted to supply an operating holding current required by a dimmer using a triac.

Recently, thanks to the development of semiconductor technology, the efficiency of light emitting diodes (LEDs) has been greatly improved. In addition, the LED has an advantage of being economical as well as being environmentally friendly because it has a much longer life and less energy consumption than conventional lighting devices such as incandescent lamps and fluorescent lamps. Due to these advantages, LED is widely used as a backlight of a traffic light or a flat panel display (eg LCD).

1 is a block diagram of an LED lighting system according to the related art, and includes a dimmer 110, a bridge diode rectifying unit 120, and an LED lighting device 130 as shown therein.

Referring to FIG. 1, a dimmer 110 and a bridge diode rectifying unit 120 are connected between a driving power source AC and an LED lighting device 130.

The dimmer 110 serves to adjust the brightness (illuminance) of the LED lighting device 130 according to a user's request, and mainly uses triacs for this purpose. In this case, the dimmer 110 adjusts the conduction angle of the triac to vary the RMS voltage flowing through the LED lighting device 130, thereby making the light intensity of the LED which is a light source of the LED lighting device 130. Is changed.

FIG. 2 is a detailed circuit diagram of the dimmer 110. As shown therein, a variable resistor VR1 and a capacitor C1 connected in series between a first terminal T1 and a second terminal T2, and Triac TR1 connected in parallel with a series connected variable resistor VR1 and a capacitor C1, connected between a connection point of the variable resistor VR1 and a capacitor C1 and a gate of the triac TR1. Diac (D1).

The dimmer 110 adjusts the value of the variable resistor VR1 to set a time required to reach the diac triggering voltage applied to the capacitor C1. The power applied to the LED which is the light source of the LED lighting apparatus 130 is determined according to the set time, thereby determining the illuminance level of the LED lighting apparatus 130.

3 shows the input and output voltage waveforms of the dimmer 110. That is, FIG. 3A illustrates a waveform of an AC power supply voltage supplied from the driving power source AC to the dimmer 110. FIG. 3B illustrates an example waveform of the output voltage when the triggering voltage of the triac TR1 is adjusted as described above for dimming in the dimmer 110. 3 (c) shows the waveform of the voltage supplied to the LED lighting device 130 by full-wave rectifying the output voltage as shown in FIG. 3 (b) through the bridge diode rectifier 120.

The triac TR1 has an important parameter of sustain current that is directly related to LED light emission. The holding current means a minimum anode current for the triac TR1 to operate in the conduction region. Therefore, the triac TR1 may not remain on after being triggered without a current greater than the holding current passing through the first and second terminals T1 and T2.

At a small current level below the holding current, once the dimmer conducts, the current of the LED lighting device 130 does not satisfy the holding current requirement, so that the triac TR1 and the dimmer 110 in the dimmer 110 are not connected. Enters a retriggering state causing flickering of the LED light.

In view of this, in the conventional LED lighting system, dummy loads are provided at both ends of the LED lighting device in order to prevent the triac and the dimmer in the dimmer from entering the retriggering state causing flickering of the LED light because the holding current requirement is not satisfied. Are installed in parallel to provide sufficient induction current. However, in this case, the energy efficiency is reduced due to the induction of the power of the dummy load, and there are disadvantageous problems in thermal management of the internal power supply.

Accordingly, an object of the present invention is to stabilize the operation of the dimmer by obtaining the difference between the current flowing through the LED light emitting element and the preset operation holding current and providing the difference current as the operation maintenance compensation current of the triac of the dimmer.

The objects of the present invention are not limited to the above-mentioned objects. Other objects and advantages of the invention will be more clearly understood by the following description.

The present invention for achieving the above object, the dimmer for adjusting the conduction angle of the triac; And an LED illuminator whose illumination is controlled by adjusting the conduction angle of the triac of the dimmer, wherein the LED illuminator comprises a current flowing through each LED string channel of the LED array unit of the LED illuminator through an LED constant current device. A first current detector configured to detect and output a voltage corresponding thereto and add the detected voltages and output the sum of the detected voltages; An error current calculator configured to compare the voltage input from the first current detector with a reference voltage supplied from a reference voltage generator, and output a difference voltage according thereto; And a dimmer constant current device for supplying a compensating current necessary to maintain operation of the triac of the dimmer based on the voltage supplied from the error current calculating unit.

Another invention for achieving the above object, the dimmer for adjusting the conduction angle of the triac; And an LED illuminating device whose illuminance is controlled by adjusting the conduction angle of the triac of the dimmer, wherein the LED illuminating device outputs a control voltage to the LED constant current device to each LED string channel of the LED array unit of the LED illuminating device. LED drive control unit for controlling the lighting of the lights; A second current detector configured to detect a current flowing in any one of the LED string channels of the LED array of the LED lighting apparatus based on the control voltage output from the LED driving controller, add the detected results, and output a corresponding voltage; An error current calculator configured to compare the voltage input from the second current detector to a reference voltage supplied from a reference voltage generator, and output a difference voltage according thereto; And a dimmer constant current device for supplying a compensating current necessary to maintain operation of the triac of the dimmer based on the voltage supplied from the error current calculating unit.

The present invention calculates the difference between the current flowing through the light emitting device of the LED lighting device and the predetermined operation holding current in the LED lighting system, and supplies the difference current as the operation maintenance compensation current of the triac of the dimmer, thereby reducing the power consumption according to the addition of the dimmer. Minimize, there is an effect that can stabilize the operation of the dimmer.

1 is a block diagram of an LED lighting system according to the prior art.
FIG. 2 is a detailed circuit diagram of the dimmer of FIG. 1.
3A to 3C are input / output voltage waveform diagrams of the dimmer in FIG.
4 is a block diagram of a dimmer operation maintaining circuit of the LED lighting system according to the embodiment of the present invention.
FIG. 5 is a detailed circuit diagram of the current detector of the first current detector of FIG. 4.
FIG. 6 is a detailed circuit diagram of an adder of the first current detection unit in FIG. 4.
FIG. 7 is a detailed circuit diagram of the error current calculator of FIG. 4.
8 is a block diagram of a dimmer operation maintaining circuit of the LED lighting system according to another embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

4 is a block diagram of the dimmer operation maintaining circuit of the LED lighting system according to the embodiment of the present invention, and as shown therein, includes a dimmer 410, a bridge diode rectifying unit 420, and an LED lighting device 430.

The dimmer 410 adjusts the conduction angle of the triac according to the user's request to vary the RMS voltage flowing through the LED lighting device 430, thereby adjusting the conduction angle of the triac. Light intensity (illuminance) is adjusted. However, since the dimmer 410 is stably received by the dimmer constant current device 439 of the LED illuminator 430 and stably supplied with a holding current directly related to the LED light emission of the LED illuminator 430, it is stable even after triggering. It can be kept on.

The bridge diode rectifier 420 is full-wave rectified AC power output by adjusting the conduction angle by the dimmer 410 to supply the driving power of the LED lighting device 430.

The LED lighting device 430 is a power supply unit 431, LED array unit 432, LED drive control unit 433, LED constant current device 434, the first current detection unit 435, low-pass filter 436, And a reference voltage generator 437, an error current calculator 438, and a dimmer constant current device 439.

The power supply unit 431 smoothes the voltage in the form of a pulse current output from the bridge diode rectifier 420, and converts the voltage into a level (eg, VCC, VDD) required by each unit in the LED lighting device 430. do.

The LED array unit 432 has an LED string for each channel, one end of each LED string is connected to the output terminal of the bridge diode rectifier 420, the other end of the LED constant current device 434 The channel is connected.

The LED driving control unit 433 controls the driving of the LED constant current device 434 so that the LED strings arranged as described above in the LED array 432 are turned on in a corresponding pattern.

The first current detector 435 includes a plurality of current detectors DET1 -DETn and a summer ADD.

The current detectors DET1 to DETn are connected to respective LED string channels of the LED constant current device 434 to detect currents flowing through the channels.

FIG. 5 shows a detailed circuit diagram of an embodiment of any one of the current detectors DET1 to DETn, in which the drain is connected to the detection node N_DET and the source is the output node. A control voltage V_CTL is supplied to a MOS transistor M51 connected to N_OUT, a resistor R51 connected between the output node N_OUT and a ground terminal, and a non-inverting input terminal, and an inverting input terminal of the output node. It is connected to (N_OUT), the output terminal includes a first operational amplifier (OP51) connected to the gate of the MOS transistor (M51).

Referring to FIG. 5, the first operational amplifier OP51 amplifies the control voltage V_CTL supplied from the controller (not shown) and outputs the amplified control voltage V_CTL to the gate of the MOS transistor M51.

However, the detection node N_DET connected to the drain of the MOS transistor M51 is connected to the other end side of the corresponding LED string of the LED array 432 through the corresponding LED string channel of the LED constant current device 434. Connected.

Accordingly, a current flowing through the corresponding LED string of the LED array 432 is detected through the MOS transistor M51, and the current detection voltage V is output through the output node N_OUT.

Each of the current detectors DET1 -DETn is configured as shown in FIG. .

The summer ADD sums and amplifies the current detection voltages V1 -Vn respectively detected and output by the current detectors DET1-DETn to generate an output voltage VOUT accordingly.

FIG. 6 is a detailed circuit diagram of an embodiment of the adder ADD. As shown in FIG. And a second operational amplifier OP61 that amplifies and outputs the voltage summed by -Rn.

The current detection voltages V1 -Vn respectively detected and output by the current detectors DET1-DETn are output to the summing node N_SUM through the resistors R1-Rn. Therefore, the summation result of the current detection voltages V1 -Vn appears in the summing node N_SUM.

The summation voltage appearing at the summation node N_SUM is amplified by the second operational amplifier OP61, and the output voltage Vout thereof is displayed at its output terminal. The resistor R0 is connected between the output terminal of the second operational amplifier OP61 and the inverting input terminal, and the non-inverting input terminal is connected to the ground terminal.

Therefore, the output voltage Vout of the second operational amplifier OP61 is represented by Equation 1 below.

A is an amplification degree of the second operational amplifier OP61.

The low pass filter 436 averages the output voltage Vout output from the first current detector 435 to remove noise components.

The error current calculator 438 compares the voltage input from the low pass filter 436 with a reference voltage supplied from the reference voltage generator 437, obtains the difference voltage, and amplifies and outputs the difference voltage.

FIG. 7 is a detailed circuit diagram of an exemplary embodiment of the error current calculating unit 438. As shown in FIG. 7, the non-inverting input terminal is connected to the reference voltage terminal Vref through the resistor R71. The inverting input terminal of the third operational amplifier OP71 is connected, and the resistor R72 is connected between the inverting input terminal of the third operational amplifier OP71 and the output terminal Vout.

Referring to FIG. 7, the output voltage of the first current detector 435 is input to the non-inverting input terminal of the third operational amplifier OP71 through an input terminal Vin and a resistor R71, and the reference voltage terminal ( Vref) is a preset reference voltage is input to the non-inverting input terminal of the third operational amplifier OP71. Accordingly, the third operational amplifier OP71 compares the voltage input from the low pass filter 436 with the reference voltage supplied from the reference voltage generator 437, obtains a difference voltage according thereto, and amplifies it at a preset amplification rate. Output

The dimmer constant current device 439 additionally supplies a minimum current necessary for maintaining the triac operation of the dimmer 410 based on the voltage supplied from the error current calculator 438.

As a result, the reference voltage corresponding to the minimum current required to maintain the operation of the triac of the dimmer 410 is set in advance, and the current flowing through each of the LED strings of the LED array 432 is performed through the above process. The voltage corresponding to the detected current was detected and compared with the reference voltage to supply a current corresponding to the difference as a compensation current required for maintaining the triac of the dimmer 410.

By doing so, power consumption due to the addition of the dimmer 410 can be minimized and the operation of the dimmer 410 can be stabilized.

8 is a block diagram of a dimmer operation maintaining circuit of an LED lighting system according to another exemplary embodiment of the present invention. As shown in FIG. 8, the dimmer 810, the bridge diode rectifying unit 820, and the LED lighting device 830 are illustrated. Include.

The LED lighting device 830 is a power supply unit 831, LED array unit 832, LED drive control unit 833, LED constant current device 834, the second current detector 835, the reference voltage generator 836 ), An error current calculating unit 837, and a constant current device 838 for a dimmer.

When FIG. 8 is compared with FIG. 4, the dimmer 810 and the bridge diode rectifier 820 of FIG. 8 have the same configuration and operation as the dimmer 410 and the bridge diode rectifier 420 of FIG. 4.

However, when the LED lighting device 830 of FIG. 8 is compared with the LED lighting device 430 of FIG. 4, the action of the first current detector 435 of FIG. 4 and the second current detector 835 of FIG. 8 are different. Do. In addition, in the LED lighting device 830 of FIG. 8, unlike the LED lighting device 430 of FIG. 4, a low-pass filter is not used at the output terminal of the second current detector 835, but a low-pass filter may be added as necessary. .

The second current detector 835 calculates the amount of current flowing through one LED string on the LED array 832 based on a control voltage supplied from the LED drive controller 833 to the LED constant current device 834. It is different from the first current detector 435 to obtain the amount of current flowing through the entire LED string of the LED array unit 832 by multiplying the current amount by the total number of LED string channels.

The second current detector 835 uses the amount of current obtained as described above, and uses the reference voltage generator 836, the error current calculator 837, and the constant current device 838 for the dimmer to make a try of the dimmer 810. The series of actions of supplying the compensation current necessary for maintaining the operation of the liquid are the same as in FIG.

Although the preferred embodiment of the present invention has been described in detail above, the scope of the present invention is not limited thereto, and may be implemented in various embodiments based on the basic concept of the present invention defined in the following claims. Such embodiments are also within the scope of the present invention.

410: dimmer 420: bridge diode rectifier
430: LED lighting device 431: power supply
432: LED array 433: LED drive control unit
434: constant current device for LED 435: first current detection unit
436: low pass filter 437: reference voltage generator
438: error current calculation unit 439: constant current device for the dimmer

Claims (7)

A dimmer for adjusting the conduction angle of the triac;
In the dimmer operating maintaining circuit of the LED lighting system comprising an LED lighting device is controlled the illuminance by adjusting the conduction angle of the triac of the dimmer,
The LED illumination device includes:
A first current detector for detecting a current flowing through each LED string channel of the LED array of the LED lighting apparatus through an LED constant current device, outputting a voltage corresponding thereto, and summing the output voltages;
An error current calculator configured to compare the voltage input from the first current detector with a reference voltage supplied from a reference voltage generator, and output a difference voltage according thereto;
And a dimmer constant current device for supplying a compensating current necessary for maintaining operation of the triac of the dimmer based on the voltage supplied from the error current calculating unit.
The method of claim 1, wherein the first current detection unit
A plurality of current detectors connected to respective LED string channels of the LED constant current device to detect current flowing through the corresponding channel;
And a summer for summing and amplifying current detection voltages respectively detected by the plurality of current detectors and outputting the amplified currents, thereby generating output voltages according to the dimmers.
The method of claim 2, wherein the current detector
A MOS transistor having a drain connected to the detection node and a source connected to the output node;
A resistor connected between the output node and a ground terminal;
A dimmer operation of the LED lighting system, comprising: a control voltage supplied to a non-inverting input terminal, an inverting input terminal connected to the output node, and an output terminal connected to a gate of the MOS transistor. Holding circuit.
The method of claim 2, wherein the summer is
A plurality of resistors for summing the current detection voltages obtained by the plurality of current detectors;
And a second operational amplifier configured to amplify and output voltages summed by the plurality of resistors.

2. The dimmer operation maintaining circuit of claim 1, further comprising a low pass filter at an output terminal of the first current detection unit.
The display device of claim 1, wherein the error current calculator comprises a third operational amplifier configured to amplify and output an output voltage of the first current detector supplied through an inverting input terminal based on a reference voltage input to a non-inverting input terminal. Dimmer operation maintaining circuit of the LED lighting system, characterized in that.
A dimmer for adjusting the conduction angle of the triac;
In the dimmer operating maintaining circuit of the LED lighting system comprising an LED lighting device is controlled the illuminance by adjusting the conduction angle of the triac of the dimmer,
The LED illumination device includes:
An LED driving control unit outputting a control voltage to an LED constant current device to control lighting of each LED string channel of the LED array unit of the LED lighting device;
A second current detector configured to detect a current flowing in any one of the LED string channels of the LED array of the LED lighting apparatus based on the control voltage output from the LED driving controller, add the detected currents, and output a corresponding voltage;
An error current calculator configured to compare the voltage input from the second current detector to a reference voltage supplied from a reference voltage generator, and output a difference voltage according thereto;
And a dimmer constant current device for supplying a compensating current necessary to maintain operation of the triac of the dimmer based on the voltage supplied from the error current calculating unit.

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