KR20160084049A - An apparatus for driving a light emitting device - Google Patents

Abstract

Disclosed is an apparatus for driving a light emitting device, capable of preventing degradation of power efficiency. According to an embodiment of the present invention, the apparatus includes: a voltage generating unit for providing a direct current signal for driving a light emitting unit; a sensing resistor connected to a ground power source at one end thereof; and a dimming unit including a switch connected between the light emitting unit and the sensing resistor and switched by a constant-current control signal, and controlling the amount of current flowing in the light emitting unit based on the constant-current control signal. The dimming unit compares a distributed voltage which is resulted from distributing a voltage of a first node connected to the light emitting unit and the switch and a voltage of a second node connected to the switch and the sensing resistor, with a preset constant voltage, and adjusts the amount of a current flowing between a third node connected to an output end of the voltage generating unit and an input end of the light emitting unit, and the ground power source based on the compared result. The voltage generating unit adjusts a level of the direct current signal based on the amount of a current flowing between the third node and the ground power source.

Description

TECHNICAL FIELD [0001] The present invention relates to a light emitting element driving apparatus,

The embodiment relates to a light-emitting element driving apparatus.

In recent years, there has been a growing interest in LED lighting, which has a brightness comparable to that of an illumination device such as an incandescent lamp, while operating with low power consumption. In particular, research and development of an illumination driving apparatus for driving LED lighting by controlling a current so that a constant current flows through the LED illumination is actively under way.

Such an illumination driving apparatus has various illumination directing functions. In particular, by changing dimming of LED elements arranged in a serial-parallel connection, various illumination directing is possible.

2. Description of the Related Art Generally, an illumination driving apparatus includes a rectifying circuit for rectifying a radio wave output from an AC power source, a transforming circuit for converting the magnitude of a voltage output from the rectifying circuit and outputting the magnitude of the voltage, A smoothing circuit for smoothing the voltage output from the transforming circuit to output a stable DC voltage and supplying the output voltage to the LED module; and a rectifying circuit for rectifying the LED current so that a constant driving current flows through the LED module And a dimming control circuit for controlling dimming by controlling the current flow of the LED module by controlling the constant current driving circuit by a PWM (Pulse Width Modulation) method.

The embodiment provides a light emitting element driving apparatus capable of eliminating waste of power due to fluctuation of an operating voltage and preventing power efficiency from being lowered.

A light emitting device driving apparatus according to an embodiment includes a voltage generating unit for providing a direct current signal for driving a light emitting unit, a sensing resistor having one end connected to a ground power source, And a dimming unit including a switch connected between the light emitting unit and the sensing resistor and switched by a constant current control signal and adjusting a current amount of a current flowing in the light emitting unit based on the constant current control signal, And a voltage divider that divides the voltage between a first node connected to the light emitting unit and the switch and a second node connected to the sensing resistor to a predetermined divided voltage and a predetermined constant voltage, And adjusts a current amount of a current flowing between a third node connected to the output terminal of the voltage generating unit and the input terminal of the light emitting unit and the ground power supply, and the voltage generating unit is based on the amount of current flowing between the third node and the ground power supply Thereby adjusting the level of the DC signal.

Wherein the dimming unit comprises: a voltage distributor for distributing the voltage between the first node and the second node and outputting a divided voltage according to the distributed result; And a voltage generation control unit for adjusting a current amount of a current flowing between the third node and the ground power supply based on a result of comparison between the distribution voltage and the predetermined constant voltage.

The dimming unit may further include an amplifier for amplifying a voltage of the first node and outputting an amplified voltage. The voltage divider may output the divided voltage according to a result of dividing the amplified voltage.

The voltage divider may include a plurality of resistors connected in series, and the distributed voltage may be output from any one of the connection nodes of the plurality of resistors.

The dimming unit may further include a current amount detecting unit that detects the amount of current flowing between the third node and the ground power source and provides the detected result to the voltage generating unit.

The current amount detecting unit may include a light emitting diode connected between the third node and the constant voltage supplying unit and the intensity of light generated in the light emitting diode is proportional to the amount of current flowing between the third node and the ground power supply I can do it.

The dimming unit may further include an operational amplifier including a first input terminal receiving the constant current control signal, a second input terminal connected to the second node, and an output terminal.

The embodiment can eliminate the power waste due to the fluctuation of the operating voltage and prevent the power efficiency from being lowered.

1 shows a configuration diagram of a lighting apparatus according to an embodiment.
Fig. 2 shows an embodiment of the current amount detecting unit shown in Fig.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG. In the description of the embodiments, it is to be understood that each layer (film), region, pattern or structure may be referred to as being "on" or "under" a substrate, each layer It is to be understood that the terms " on "and " under" include both " directly "or" indirectly " do. In addition, the criteria for the top / bottom or bottom / bottom of each layer are described with reference to the drawings.

In the drawings, dimensions are exaggerated, omitted, or schematically illustrated for convenience and clarity of illustration. Also, the size of each component does not entirely reflect the actual size. The same reference numerals denote the same elements throughout the description of the drawings.

Fig. 1 shows a configuration diagram of a lighting apparatus 100 according to an embodiment.

Referring to FIG. 1, the lighting apparatus 100 includes a light emitting portion 101 and a light emitting element driving device 102 for driving the light emitting portion 101.

The light emitting unit 101 includes a plurality of light emitting device arrays D1 to Dn, n> 1, which are connected in series.

Each of the plurality of light emitting device arrays D1 to Dn, a natural number of n> 1, may include one or more light emitting devices, for example, a light emitting diode.

When the number of the light emitting elements included in the light emitting element array is plural, the plurality of light emitting diodes may be connected to each other in series, in parallel, or in series and parallel.

The light emitting element driving apparatus 102 includes an AC power source 110, an EMI filter 115, a rectifier 120, a power factor improving unit 125, a voltage generating unit 130, a dimming unit 140, (Rsen).

The AC power supply unit 110 provides an AC signal AC.

At this time, the AC signal AC may be an AC voltage, and / or an AC current.

The EMI (ElectroMagnetic Interference) filter 115 is for blocking external electromagnetic noise, and removes a noise, for example, a conductive noise included in the AC signal AC provided from the AC power source unit 110. EMI filter 115 may be implemented to include at least one of a capacitor, a transformer, and an inductor.

The rectifier 120 rectifies the AC signal AC having the electromagnetic noise removed by the EMI filter 115 and provides a ripple current (VR) according to the rectified result.

For example, the rectifier 120 can full-wave rectify the AC signal AC and output the rectified signal VR according to the full-wave rectified result. That is, the rectified signal VR may be a signal in which the AC signal AC is full-wave rectified.

The rectifier 120 may be implemented by a radio wave diode bridge circuit including four diodes connected by bridges, but is not limited thereto.

The power factor correcting unit 125 corrects the power factor of the rectified signal VR by adjusting the phase difference between the voltage and the current of the rectified signal and outputs the rectified signal VR1 with the corrected power factor.

The voltage generating unit 130 converts the level of the rectified signal VR1 whose power factor is corrected by the power factor improving unit 125 based on the dimming signal CT provided from the dimming unit 140, And outputs the level-converted DC signal VR2. For example, the direct current signal VR2 may be a direct current voltage.

The level of the direct current signal VR2 output from the voltage generating unit 130 may be set based on the dimming signal CT provided from the dimming unit 140. [

The DC signal VR2 output from the voltage generating unit 130 is provided to the light emitting unit 101. [ For example, the direct current signal VR2 output from the voltage generating unit 130 may be provided to the input terminal 105 of the light emitting unit 101. The input terminal 105 of the light emitting unit 101 may be a positive terminal of the first light emitting device array D1 among the light emitting device arrays D1 to Dn connected in series.

The voltage generating unit 130 may be implemented as a converter capable of converting the DC level of the rectified signal VR1. For example, the voltage generator 130 may be implemented to include at least one of a DC-DC converter, a resonant LLC half bridge converter, a flyback converter, or a buck converter. have.

The dimming unit 140 connects the light emitting unit 101 and the sensing resistor Rsen and controls the current flowing to the light emitting unit 101 based on the constant current control signal Vset provided from the dimming control unit 148 The brightness of the light emitting portion 101 is adjusted.

The dimming unit 140 is provided from the voltage generator 130 so that the voltage VN between the output terminal 106 of the light emitting unit 101 and the one end 107 of the sensing resistor Rsen is maintained at a preset reference voltage The level of the direct current signal VR2 is changed.

For example, the predetermined reference voltage may be, but is not limited to, the voltage between the source and drain of the switch 142 implemented as a transistor (e.g., FET).

The output terminal 106 of the light emitting unit 101 may be a negative terminal of the last light emitting device array Dn among the light emitting device arrays D1 to Dn connected in series.

The dimming unit 140 is connected between the output terminal of the voltage generating unit 130 and the input terminal 105 of the light emitting unit 101 based on a result of comparison between the divided voltage Vdiv and the predetermined constant voltage VREF, The current amount of the current I1 flowing between the node N3 and the ground power source GND is adjusted.

The distribution voltage Vdiv is a voltage between the voltage of the first node N1 to which the light emitting portion 101 and the switch 142 are connected and the voltage between the switch 142 and the second node N2 to which the sensing resistor Rsen is connected Lt; / RTI > VN).

For example, the distribution voltage Vdiv may be a voltage according to the result of the division, amplifying the voltage of the first node N1, distributing the amplification voltage according to the amplified result.

The voltage generating unit 130 can adjust the level of the direct current signal VR2 based on the amount of the current I1 adjusted by the dimming unit 140. [

The dimming unit 140 may include a switch 142, a first amplifier 146, a dimming control unit 148, a voltage generation control unit 149, and a sensing resistor Rsen.

The switch 142 is connected between the output terminal 106 of the light emitting portion 101 and one end 107 of the sensing resistor Rsen and is switched based on the constant current control signal Vset provided from the dimming control portion 148 .

For example, the switch 142 may be implemented as a transistor, for example, an FET transistor or a BJT transistor.

For example, the switch 142 includes a drain connected to the output terminal 106 of the light emitting portion 101, a source connected to one end 107 of the sensing resistor Rsen, And an NMOS transistor including a gate to which an output of the NMOS transistor is input, but the present invention is not limited thereto.

The switch 142 is implemented in various forms for electrically connecting the output terminal 106 of the light emitting portion 101 and the one end 107 of the sensing resistor Rsen in response to the output CS of the first amplifier 146 .

The first amplifier 146 amplifies the voltage of the second node N2 and the constant current control signal Vset provided from the dimming control unit 148 and outputs the amplified signal CS according to the amplified result.

For example, the constant current control signal Vset provided from the dimming control unit 148 of FIG. 1 may be a pulse signal such as a pulse width modulation (PWM) signal, but the present invention is not limited thereto. In another embodiment, Or the like.

The dimming control unit 148 can control the duty ratio or the magnitude of the constant current control signal Vset1 for dimming by a control signal received from the outside through a communication interface.

The first amplifier 146 includes a first input terminal 146a to which the constant current control signal Vset is input, a second input terminal 146b to be connected to the second node N2, And an output terminal 146c.

The first amplifier 146 may be implemented as an operational amplifier, but is not limited thereto. For example, the first input terminal 146a may be the positive input terminal (+) of the operational amplifier, and the second input terminal 146b may be the negative input terminal (-) of the operational amplifier.

The current flowing through the sensing resistor Rsen can be determined by the constant current control signal Vset provided by the dimming control unit 148. This makes it possible to control the current flowing through the light emitting unit 101 in the embodiment.

The sensing resistor Rsen is connected between the second node N2 and the ground (GND) power supply.

The voltage generation control unit 149 compares the distribution voltage Vdiv according to the result of distributing the voltage between the first node N1 and the second node N2 with the predetermined constant voltage VREF, The amount of current of the current I1 flowing between the third node N3 and the ground (GND) power supply can be adjusted and the adjusted result can be provided to the voltage generating unit 130. [ For example, the distribution voltage Vdiv may be a voltage resulting from voltage division of the amplification voltage DV according to the result of amplifying the voltage of the first node N1.

The voltage generation control unit 149 may include a second amplifier 210, a voltage distribution unit 215, a current amount detection unit 220, and a constant voltage supply unit 230.

The second amplifier 210 amplifies the voltage of the first node N1 and outputs an amplification voltage DV according to the amplified result. Since the voltage change of the first node N1 and the second node N2 may be a small value (for example, less than 1 V) in accordance with the change of the operation voltage of the light emitting element arrays of the light emitting portion 101, May be configured to amplify the voltage of the first node N1 to a voltage level comparable to a predetermined constant voltage of the constant voltage supply unit 230. [

The voltage divider 215 is connected between the output terminal of the second amplifier 210 and the second node N2 and distributes the amplified voltage DV of the second amplifier 210, (Vdiv).

For example, the voltage divider 215 may include a plurality of resistors R1 and R2 connected in series or series-parallel between the first node N1 and the second node N2.

For example, the voltage divider 215 may include a first resistor R1 and a second resistor R2 that are connected in series between the first node N1 and the second node N2, and the first resistor R1 R1 from the distribution node N4 to which the second resistor R2 is connected, and the distribution voltage Vdiv from the distribution node N4 to which the second resistor R2 is connected. Where the distribution node N4 may be any of the connection nodes of the series connected resistors.

The current amount detection unit 220 is connected between the third node N3 connected to the output terminal of the voltage generation unit 130 and the input terminal 150 of the light emitting unit 101 and the ground power source GND, ) And the ground power source (GND).

FIG. 2 shows an embodiment of the current amount detection unit 220 shown in FIG.

2, the current amount detecting unit 220 may include a zener diode 222, a resistor 224, and a light emitting diode 226 connected in series between a node N2 and a constant voltage supply unit 230. [ At least one of the Zener diode 222 and the resistor 224 may be omitted in the current amount detecting section 220 of another embodiment.

The intensity or intensity of light generated in the light emitting diode 226 may be proportional to the amount or intensity of the current I1 flowing between the node N2 and the ground GND.

The voltage generating unit 130 may adjust the level of the direct current signal VR2 provided to the light emitting unit 101 based on the light intensity of the light emitting diode 226. [

For example, the voltage generator 130 may be implemented as a phototransistor that senses light intensity of the light emitting diode 226 and generates a current proportional to the sensed light intensity, but is not limited thereto .

The constant voltage supply unit 230 compares the distribution voltage Vdiv with a predetermined constant voltage (for example, VREF) and calculates the amount of current I1 flowing between the third node N3 and the ground GND based on the comparison result . For example, VREF may be 1.25 [V] or 2.5 [V], but is not limited thereto.

The constant voltage supply unit 230 is connected to the distribution node N4 and controls the amount of current I1 flowing between the third node N3 and the ground GND in order to adjust the voltage of the distribution node N4 to a predetermined constant voltage Can be adjusted.

The constant voltage supply unit 230 may serve to provide a predetermined constant voltage to the distribution node N4 by adjusting the amount of current I1 flowing between the third node N3 and the ground GND.

For example, when the distribution voltage Vdiv is equal to a predetermined constant voltage (e.g., VREF), the constant voltage supply unit 230 holds the amount of current I1 flowing between the third node N3 and the ground GND . Since the current amount of the current I1 detected from the current amount detection unit 220 is maintained at this time, the voltage generation unit 130 can maintain the current level of the direct current signal VR2.

For example, in order to make the voltage of the distribution node N4 equal to the constant voltage VREF when the distribution voltage Vdiv is greater than a predetermined constant voltage (e.g., VREF) (Vdiv> VREF), the constant- Can be increased. Since the current amount of the current I1 detected by the current amount detecting unit 220 increases at this time, the voltage supplying unit 230 can reduce the level of the direct current signal VR2.

For example, when the current amount of the current I1 increases, the intensity of the light generated in the light emitting diode 226 of the current amount detection unit 220 may increase. When the intensity of light generated by the light emitting diode 226 increases, the amount of current of the current flowing in the phototransistor of the voltage generating unit 130 may increase. When the amount of current flowing in the phototransistor increases, The generating unit 130 may reduce the level of the direct current signal VR2.

For example, in order to make the voltage of the distribution node N4 equal to the constant voltage VREF when the distribution voltage Vdiv is greater than a predetermined constant voltage (e.g., VREF) (Vdiv> VREF), the constant- Can be reduced.

On the other hand, in order to make the voltage of the distribution node N4 equal to the constant voltage VREF when the distribution voltage Vdiv is smaller than a predetermined constant voltage (e.g., VREF) (Vdiv> VREF) Lt; RTI ID = 0.0 > I1). ≪ / RTI > At this time, since the amount of the current I1 detected by the current amount detecting unit 220 decreases, the voltage supplying unit 230 can increase the level of the direct current signal VR2.

For example, when the current amount of the current I1 decreases, the intensity of light generated in the light emitting diode 226 of the current amount detection unit 220 may decrease. When the intensity of light generated by the light emitting diode 226 decreases, the amount of current flowing through the phototransistor of the voltage generating unit 130 may decrease. When the amount of current flowing through the phototransistor decreases, (130) may increase the level of the direct current signal (VR2).

In order to drive the light emitting element arrays connected in series, a first voltage, which is the sum of the rated operating voltages of the light emitting element arrays, is provided at both ends of the light emitting element arrays.

When the junction temperature of the light emitting device arrays increases, the operating voltage of the light emitting device arrays may decrease. Due to the reduction of the operating voltage of the light emitting device arrays, the voltage VN across the first node N1 and the second node N2 may increase, and the increase of the voltage may be consumed as heat, The power efficiency of the lighting apparatus can be reduced.

The change of the voltage VN between the first node N1 and the second node N2 is detected by the dimming unit 140 as a change in the amount of current and is provided from the voltage generating unit 130 The embodiment can eliminate power wasted by the switch 142 even if the operating voltage of the light emitting portion 101 fluctuates and the power efficiency of the lighting apparatus 100 is lowered by adjusting the level of the DC signal VR2 Can be prevented.

The difference between the voltage supplied from the voltage generating part 130 and the voltage actually applied to the light emitting part 101 due to the reduction of the operating voltage of the light emitting part 101 is not limited to the above- The power consumption of the lighting apparatus 100 may be lowered.

The features, structures, effects and the like described in the embodiments are included in at least one embodiment of the present invention and are not necessarily limited to one embodiment. Further, the features, structures, effects, and the like illustrated in the embodiments can be combined and modified by other persons having ordinary skill in the art to which the embodiments belong. Therefore, it should be understood that the present invention is not limited to these combinations and modifications.

101: light emitting portion 102: light emitting element driving device
110: AC power supply unit 115: EMI filter
120: rectifier 125: power factor improving section
130: voltage generation unit 140: dimming unit
142: switch 146: first amplifier
148: Dimming control part Rsen: Sensing resistance
210: second amplifier 215: voltage divider
220: constant voltage supply unit 230: current amount detection unit.

Claims (7)

A voltage generating unit for providing a DC signal for driving the light emitting unit;
A sensing resistor connected at one end to the ground power supply; And
And a dimming unit connected between the light emitting unit and the sensing resistor and configured to switch by a constant current control signal and to adjust an amount of current flowing in the light emitting unit based on the constant current control signal,
Wherein the dimming unit comprises:
And a voltage divider that divides the voltage between a first node connected to the light emitting unit and the switch and a second node connected to the sensing resistor to a predetermined divided voltage and a predetermined constant voltage, And adjusts the amount of current flowing between the third node connected to the output terminal of the voltage generating unit and the input terminal of the light emitting unit and the ground power source,
Wherein the voltage generating unit adjusts the level of the direct current signal based on an amount of current flowing between the third node and the ground power source. The apparatus according to claim 1,
A voltage divider dividing a voltage between the first node and the second node and outputting a divided voltage according to the divided result; And
And a voltage generation control unit for adjusting an amount of current flowing between the third node and the ground power supply based on a result of comparing the divided voltage and the predetermined constant voltage. The apparatus of claim 2,
Further comprising an amplifier for amplifying a voltage of the first node and outputting an amplified voltage,
Wherein the voltage divider outputs the divided voltage according to a result of dividing the amplified voltage. 3. The method of claim 2,
Wherein the voltage divider includes a plurality of resistors connected in series,
And the distributed voltage is output from any one of the connection nodes of the plurality of resistors. The apparatus of claim 2,
And a current amount detection unit detecting a current amount of a current flowing between the third node and the ground power source and providing the detected result to the voltage generation unit. 6. The apparatus according to claim 5,
And a light emitting diode connected between the third node and the constant voltage supply,
Wherein the intensity of light generated in the light emitting diode is proportional to the amount of current flowing between the third node and the ground power supply. The apparatus according to claim 1,
Further comprising an operational amplifier including a first input terminal to which the constant current control signal is input, a second input terminal connected to the second node, and an output terminal.

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