KR101488682B1 - Dimming control of led lighting circuits - Google Patents

Abstract

There is disclosed a dimming control circuit of an LED lighting which adjusts the amount of initial starting current until the amount of current that can operate the LED during the initial operation is reduced so that the starting time of the LED illumination is reduced so that stable dimming can be performed without significantly changing the electrical characteristics .
The present invention relates to a rectifying unit which receives an AC voltage and rectifies it into a DC voltage; An LED driving unit receiving driving voltage from the rectifying unit and driving a plurality of LEDs; A dimming unit for controlling the brightness of the LED by adjusting an AC voltage input to the rectifying unit to change a driving voltage inputted to the LED driving unit; And a current regulator for regulating the current according to the voltage output from the rectifier to supply the same current to the LED driver even if the input voltage is changed. When using the phase-cut scheme of the triac dimmer, The present invention provides a LED lighting device capable of shortening the startup time of the LED lighting even when the dimming part operates at a low dimming level by supplying a current that can be driven by the LED to the LED driving part in order to overcome the problem that the starting time of the LED lighting Thereby providing a dimming control circuit.

Description

[0001] DIMMING CONTROL OF LED LIGHTING CIRCUITS [0002]

The present invention relates to a dimming control circuit, and more particularly, to a dimming control circuit of an LED lighting which can reduce the start-up time of an LED lighting while using a phase cut method of a triac dimmer.

Generally, an LED is a light emitting device manufactured using a semiconductor manufacturing process. After the luminescence phenomenon caused by applying a voltage to a semiconductor device in the 1920s was observed for the first time, it began to be put into practical use by the end of the 1960s. Since then, researches and developments have been made to improve the efficiency of LEDs. Especially, there is a growing interest in lighting LEDs having optical characteristics enough to replace conventional incandescent lamps.

Recently, LED lighting systems with brightness characteristics comparable to those of conventional lighting devices have been announced, but studies on LED devices, LED packages, optical systems including LEDs, and LED control circuits are still in need of much research It is a situation.

Lighting system designers have struggled to control the brightness of all light sources that have emerged since filament lamps were invented. Brightness control, or dimming control, of a light source is a very important technology in a variety of fields because it can realize both a proper brightness setting and energy saving.

The most common dimming control is phase cut, also known as TRIAC dimmer. The triac dimmer does not depend on whether or not the actual target illuminator has a built-in tri-band semiconductor device. Applying phase-cut dimmers to current fluorescent or LED-based lamps presents a complex design challenge.

Most of the conventional lighting systems are very limited in the dimming range, and even the result of flicker is not satisfactory. Therefore, there is a problem that it is difficult to realize a normal operation when the input voltage is the same.

1 is a graph showing voltage characteristics in a phase cut method of a triac dimmer. Referring to FIG. 1, when the phase cut method is used for dimming, there is a problem that electric characteristics are varied due to loss of input voltage at the A portion. That is, the starting time is delayed at the same input voltage, and the closer the level of the dimmer is to zero, the more the starting time difference becomes larger.

At this time, if the resistance value between the rectifying part to be driven and the IC of the LED driving part is reduced in order to improve the starting time of the triac dimmer, the starting time can be improved by increasing the current flowing to the IC. However, this is difficult to apply when the product is a free bolt product or a product using a triac dimmer.

On the other hand, if the input voltage is increased to reduce the startup time, a relatively large amount of current may flow, which may damage the IC. That is, a product using a phase-cut triac dimmer has a different input voltage depending on the dimmer level. Therefore, when the dimmer level is high despite the single voltage, the input voltage increases and the amount of current increases. Therefore, May damage the IC.

In the phase-cut type dimmer, when the dimmer level is small, the input voltage is low and when the dimmer level is high, the input voltage is high.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a method of controlling an initial start-up current by adjusting an initial start-up current until an amount of current that can operate an LED during an initial operation is reduced, The dimming control circuit of the LED lighting capable of performing stable dimming.

According to an exemplary embodiment of the present invention, there is provided a dimming control circuit for an LED lighting device, comprising: a rectifying part for receiving an AC voltage and rectifying the AC voltage to a DC voltage; A dimming unit for controlling the brightness of the LED by controlling an AC voltage inputted to the rectifying unit and changing a driving voltage inputted to the LED driving unit; And a current regulator for regulating the current so that the same current can be supplied to the LED driver even if the input voltage is changed.

At this time, the dimming unit may use a phase cut method using a triac.

The current regulating unit includes a first resistor R1 electrically connected to the rectifying unit and a second resistor R2 connected in series with the first resistor R1 and the first resistor R1, A third resistor R3 connected in parallel; A fourth resistor R4 connected in parallel with the third resistor R3 and electrically connected to the LED driver, and a fifth resistor R5 connected in series with the fourth resistor R4; A first capacitor (C1) connected in parallel with the second resistor (R2) to store a driving voltage; The first stage is electrically connected to the third resistor R3, the second stage is electrically connected to the first capacitor C1, the third stage is grounded, A first switching element TR1 turned on / off according to a voltage; A second capacitor C2 connected in series to the third resistor R3 and connected in parallel with the first switching device TR1 to store a driving voltage; The first end is electrically connected to the fourth resistor R4, the second end is electrically connected to the second capacitor C2, the third end is electrically connected to the LED driver, And a second switching device (TR2) connected in parallel between the third stage and the second capacitor (C2) to turn on / off according to a driving voltage stored in the second capacitor (C2). When the input voltage is low, The switching element is short-circuited to flow only the current corresponding to the fourth resistor R4. If the input voltage is high, the second switching element is opened so that current flows through the fourth resistor R5 and the fourth resistor R5 .

At this time, the values of the first resistor R1 and the second resistor R2 are determined by the voltage ratio at which the first switching device TR1 can turn on. When the input voltage is high or low, the first switching device TR1 And whether or not the operation is determined.

The dimming control circuit of the LED lighting according to the present invention may delay the start time of the LED compared to the same input voltage when using the phase cut method of the triac dimmer. By supplying a current capable of driving the LED to the LED driving unit, It is possible to shorten the starting time of the LED lighting even when operating with the low dimming, and it is possible to supply the same current to the LED driver even when the input voltage is changed.

1 is a graph showing voltage characteristics in a phase cut method of a triac dimmer.
2 is a block diagram schematically showing a configuration of a dimming control circuit of an LED lighting according to an embodiment of the present invention.
3 schematically shows a circuit diagram of a dimming control circuit of an LED lighting according to an embodiment of the present invention.
4 is a circuit diagram showing the current regulator in detail in the dimming control circuit of LED lighting.

The present invention is capable of various modifications and various forms, and specific embodiments are illustrated in the drawings and described in detail in the text. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms first, second, etc. may be used to describe various elements, but the elements should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprising" or "having ", and the like, are intended to specify the presence of stated features, integers, steps, operations, elements, parts, or combinations thereof, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, parts, or combinations thereof.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the meaning in the context of the relevant art and are to be interpreted as ideal or overly formal in meaning unless explicitly defined in the present application Do not.

FIG. 2 is a block diagram schematically showing a configuration of a dimming control circuit of an LED lighting according to an embodiment of the present invention, and FIG. 3 is a block diagram schematically showing a circuit diagram of a dimming control circuit of an LED lighting according to an embodiment of the present invention will be.

2 to 3, the LED lighting dimming control circuit according to an embodiment of the present invention includes an LED driving unit 100, a rectifying unit 200, a dimming unit 300, and a current adjusting unit 400 can do.

The LED driving unit 100 is connected to the plurality of LEDs 110 and receives power from the rectifying unit 200 to drive the plurality of LEDs 110.

The rectifier 200 receives an AC voltage from the outside and rectifies it to a DC voltage.

The dimming unit 300 may regulate an alternating voltage input to the rectifying unit 200 to control the brightness of the LED by rectifying the rectified voltage through the rectifying unit 200 and changing a driving voltage supplied to the LED driving unit 100 . For example, the dimming unit 300 may adjust the input voltage using a phase-cutting method using a triac.

The current regulator 400 can improve the startup time while keeping the amount of current input to the LED driver constant. That is, the two switching elements are turned on / off according to the input voltage so that a constant current can be supplied even when the input voltage is high or the input voltage is low. The detailed description will be described in more detail when the following circuit is explained.

Hereinafter, the current regulator 400 will be described in detail with reference to the drawings.

4 is a circuit diagram showing the current regulator 400 in detail in the dimming control circuit of LED lighting.

4, the current regulator 400 includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, A first capacitor C1, a second capacitor C2, a first switching device TR1, a second switching device TR2, and the like.

That is, a first resistor R1 electrically connected to the rectifying unit, a second resistor R2 connected in series with the first resistor R1, and a first resistor R1 connected in parallel with the first resistor R1 A fourth resistor R4 connected in parallel with the third resistor R3 and electrically connected to the LED driver and a fifth resistor R5 connected in series with the fourth resistor R4, ).

The first capacitor C1 is connected in parallel with the second resistor R2 to store a driving voltage. The first capacitor C1 is electrically connected to the third resistor R3. A first switching device TR1 electrically connected to the capacitor C1 and having a third terminal grounded and turned on and off according to a driving voltage stored in the first capacitor C1, A second capacitor C2 connected in series and connected in parallel to the first switching device TR1 to store a driving voltage, a first terminal electrically connected to the fourth resistor R4, A third terminal is electrically connected to the LED driving unit, a fifth resistor R5 is connected in parallel between the first terminal and the third terminal, and the second capacitor C2 And a second switching element TR2 turned on / off according to the driving voltage stored in the second switching element TR2.

When the input voltage is low, the second switching device TR2 is short-circuited to flow only the current corresponding to the fourth resistor R4. When the input voltage is high, the second switching device TR2 are opened and a current flows through the fourth resistor R4 and the fifth resistor R5 so that the same current can be supplied even if the input voltage is changed.

The first resistor R1 and the second resistor R2 are connected in series with each other and are electrically connected to the rectifying part. The first resistor R1 and the second resistor R2 may control ON / OFF states of the first switching device TR1 by adjusting a voltage supplied to the first switching device TR1.

This is to adjust the ratio of the first resistor R1 and the second resistor R2 by a voltage ratio at which the first switching device TR1 can turn on. For example, in the case of a DC voltage of 77V, when the first resistor R1 is 110K? And the second resistor R2 is 10K?, 0.7V is applied to the base of the first switching device TR1 And becomes the minimum voltage at which the first switching device TR1 can turn on. Therefore, the determination of the values of the first resistor R1 and the second resistor R2 is determined by the voltage ratio at which the first switching device TR1 can turn on. Therefore, since the first resistor R1 and the second resistor R2 are fixed, the operation of the first switching device TR1 is determined depending on whether the input voltage is high or low. Since the charging time varies depending on the capacity of the first capacitor C1, an appropriate value should be determined. At this time, it is desirable to set the capacitances of the first capacitor and the second capacitor small to reduce the startup time. However, if too small, ripples can not be caught, and there is a risk of flickering or malfunction. good.

On the other hand, when a high input voltage is supplied, the first capacitor C1 connected in parallel with the second resistor R2 is turned on until a voltage capable of turning on the first switching device TR1 by using a high voltage So that the first switching device TR1 is turned on.

The third resistor R3 is connected in parallel with the first resistor R1 and the second capacitor C2 is connected in series with the third resistor R3, TR1) to store the driving voltage. The second capacitor C2 charges the voltage using the current flowing through the third resistor R3 when the first switching device TR1 is off and the second switching device TR2 charges the voltage using the current flowing through the third resistor R3. The second switching device TR2 is turned on so that the input current can be input to the IC of the LED driver through the fourth resistor R4.

The first switching device TR1 and the second switching device TR2 may be a metal-oxide semiconductor field effect transistor (MOSFET), a bipolar junction transistor (BJT), an insulated gate bipolar transistor (IGBT) ) thyristor, and an MCT (MOS Controlled Thyristor).

Hereinafter, the operation and effects of the dimming control circuit of the LED lighting, which is one embodiment of the present invention, will be described in detail with reference to the drawings.

The operation of the present invention will now be described with reference to FIG. 4. The method of changing and adjusting the current amount resistance of the conventional IC is the same, but the phase-cut triac It can also be applied to products using dimmers.

Briefly, when the input voltage is low, the first switching device TR1 is opened and the second switching device TR2 is short-circuited, so that only the current corresponding to the fourth resistor R4 flows. On the other hand, when the input voltage is high, the first switching device TR1 is short-circuited, and the second switching device TR1 is opened, so that current flows through the fourth resistor R4 and the fifth resistor R5.

More specifically, when the input voltage is low, the first resistor R1 and the second resistor R2, whose resistance values are set such that the first switching device TR1 is turned off, The transistor TR1 is maintained in the OFF state. Accordingly, the current flows through the third resistor R3 to charge the second capacitor C2. When the charged amount rises to the voltage for turning on the second switching element TR2, The input transistor TR2 is turned ON and the input current into the IC flows through the fourth resistor R4. At this time, even if the voltage is charged by the first capacitor (C1) due to the current flowing through the first resistor (R1), it takes a long time to charge with a small current.

On the other hand, when the input voltage is high, a high current flows through the first resistor R1. At this time, the current flows directly to the ground through the first capacitor (C1), and the second capacitor (C2) can not be charged. Therefore, the second switching element TR2 is turned OFF and becomes an open state. Therefore, the input current to the IC of the LED driving part flows through the fourth resistor R4 and the fifth resistor R5.

When the input voltage is low, the current is applied to the IC through the fourth resistor R4. When the input voltage is high, the current is applied to the IC through the fourth resistor R4 and the fifth resistor R5 . In other words, when the input voltage is low, the size of the input current can be increased by using one resistor, and when the input voltage is large, the size of the input current can be reduced by using two resistors. Therefore, even if the input voltage is changed, the same current can be supplied.

As described above, in order to overcome the problem that the start-up time of the LEDs may be delayed with respect to the same input voltage when the phase-cutting method of the triac dimmer is used, the dimming control circuit of the LED lighting according to the present invention may drive LEDs This is a very useful invention having an advantage that it is possible to shorten the startup time of the LED lighting even when the dimming portion operates with low dimming by supplying the current.

While the present invention has been described in connection with what is presently considered to be practical and exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

100: LED driver 110: LED
200: rectifying part 300: dimming part
400:

Claims (4)

A rectifying part for receiving an AC voltage and rectifying it to a DC voltage;
An LED driving unit receiving a driving voltage from the rectifying unit and driving a plurality of LEDs;
A dimming unit for controlling the brightness of the LED by adjusting an AC voltage input to the rectifying unit to change a driving voltage inputted to the LED driving unit;
And a current regulator configured to regulate a current according to a voltage output from the rectifier to supply the same current to the LED driver even if an input voltage changes,
The current regulator
A second resistor R2 connected in series with the first resistor R1 and a second resistor R2 connected in parallel with the first resistor R1 in parallel with the first resistor R1, A resistor R3;
A fourth resistor R4 connected in parallel with the third resistor R3 and electrically connected to the LED driver, and a fifth resistor R5 connected in series with the fourth resistor R4;
A first capacitor (C1) connected in parallel with the second resistor (R2) to store a driving voltage;
The first stage is electrically connected to the third resistor R3, the second stage is electrically connected to the first capacitor C1, the third stage is grounded, A first switching element TR1 turned on / off according to a voltage;
A second capacitor C2 connected in series to the third resistor R3 and connected in parallel with the first switching device to store a driving voltage;
The first end is electrically connected to the fourth resistor R4, the second end is electrically connected to the second capacitor C2, the third end is electrically connected to the LED driver, And a second switching device (TR2) connected in parallel between the third stage and the fifth resistor (R5) and turned on / off according to a driving voltage stored in the second capacitor (C2)
When the input voltage is low, the second switching element is short-circuited and only the current corresponding to the fourth resistor R4 flows. If the input voltage is high, the second switching element is opened to turn on the fourth resistor and the fifth resistor R5 The dimming control circuit of the LED lighting which allows the current to flow through the LED. The apparatus of claim 1, wherein the dimming unit
Wherein a phase-cut method using a triac is used. delete The method according to claim 1,
The values of the first resistor R1 and the second resistor R2 are determined by the voltage ratio at which the first switching device TR1 can turn on and the first switching device TR1 is turned on or off according to the input voltage being high or low. Is determined in accordance with the dimming control signal.

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