KR101467803B1 - Apparatus for lighting using light emitting diode - Google Patents

Abstract

The present invention relates to a lighting apparatus, and more particularly to a lighting apparatus using a light emitting diode. The present invention provides a rectifying circuit for rectifying an AC voltage input from an AC power source; A transformer having a main winding wire and an auxiliary winding on the primary side and an output winding on the secondary side; A series circuit including a switching element connected to an output terminal of the rectifying circuit and connected to a main winding of the transformer; A light emitting unit connected to the output winding of the transformer and including a plurality of light emitting diodes; A feedback circuit for returning an error of a current flowing through the light emitting portion to a primary side; A voltage limiting circuit which is located between the rectifying circuit and the transformer and limits the maximum value of the output voltage of the rectifying circuit; And a control circuit for controlling the switching element and connected to the feedback circuit and the voltage limiting circuit to control the timing of the switching element in accordance with the limited voltage.

Description

[0001] The present invention relates to a light emitting diode (LED)

The present invention relates to a lighting apparatus, and more particularly to a lighting apparatus using a light emitting diode.

Recently, light emitting diodes (LEDs) having advantages such as efficiency, color diversity, and design autonomy have been attracting attention as a light source of illumination .

A light emitting diode is a semiconductor device which emits light when a voltage is applied in a forward direction, has a long lifetime, low power consumption, and has electrical, optical, and physical characteristics suitable for mass production.

In order to effectively utilize such a light emitting diode as a light source of an illumination, a light emitting diode driving device capable of being driven by a commercial AC power source is needed.

In small-power lighting using light emitting diodes, a driver circuit of small size, high efficiency, and high power factor is required.

SUMMARY OF THE INVENTION An object of the present invention is to provide a lighting apparatus using a light emitting diode that does not require the use of various large-capacity components in a light emitting diode lighting apparatus.

According to an aspect of the present invention, there is provided a rectifying circuit for rectifying an AC voltage input from an AC power source. A transformer having a main winding wire and an auxiliary winding on the primary side and an output winding on the secondary side; A series circuit including a switching element connected to an output terminal of the rectifying circuit and connected to a main winding of the transformer; A light emitting unit connected to the output winding of the transformer and including a plurality of light emitting diodes; A feedback circuit for returning an error of a current flowing through the light emitting portion to a primary side; A voltage limiting circuit which is located between the rectifying circuit and the transformer and limits the maximum value of the output voltage of the rectifying circuit; And a control circuit for controlling the switching element and connected to the feedback circuit and the voltage limiting circuit to control the timing of the switching element in accordance with the limited voltage.

Here, the voltage limiting circuit may include: a voltage detecting unit that generates a detection signal of the output voltage of the rectifying circuit; An average voltage detector for generating an average value of the output voltage of the rectifier circuit; And a voltage limiting unit for dividing the average value and limiting the maximum value of the detection signal.

At this time, the voltage detecting unit can generate the detection voltage by dividing the output voltage of the rectifying circuit by the voltage dividing resistor and reducing the noise through the noise absorbing capacitor.

The average voltage detector may smooth the output voltage of the rectifier circuit through a resistor and a capacitor to generate an average voltage at the capacitor terminal.

On the other hand, the voltage restricting unit is characterized by dividing the average value and connecting the detection voltage by using a transistor.

Here, a smoothing circuit may be provided between the output winding of the transformer and the light emitting portion.

The feedback circuit includes: a first feedback circuit for detecting an error of a current flowing through the light emitting portion; And a second feedback circuit coupled to the first feedback circuit and supplying the current feedback to the control circuit as an error signal.

Here, the first feedback circuit may include: a detection resistor for detecting a voltage flowing through the light emitting diode; Reference voltage; And an output current comparator for comparing the voltage by the detection resistor and a reference voltage.

The second feedback circuit may be connected to the voltage limiting circuit and the control circuit through a multiplier.

Here, the voltage limiting circuit may include, as another example, a voltage detecting unit for generating a detection signal of the output voltage of the rectifying circuit; And a voltage limiter for limiting a maximum value of the detection signal.

At this time, the voltage restricting portion may include a zener diode.

Here, a snubber circuit may be further provided between the voltage limiting circuit and the transformer.

The present invention has the following effects.

Such an illumination device can be applied to a power factor correction circuit of an input full-wave rectification reference type, and can be applied to an insulation type and a non-insulation type.

In the case of the insulation type, it is also applicable to a configuration in which the detection signal is changed to return the current and / or voltage of the output.

Further, the present invention can be applied to a primary-side detection method in which various proposed secondary-side information of a transformer is estimated from specific current and voltage information on the primary side by applying a specific calculation.

Such a lighting apparatus can have a simple circuit configuration, and it is not necessary to use various components having a large capacity, so that the size of the lighting circuit can be reduced.

In addition, in addition, the ripple of the output current can be smoothened to improve the quality of the light emitting diode illumination device.

1 is a circuit diagram showing an example of a light emitting diode illumination device.
2A and 2B are waveform diagrams showing a full-wave rectification detection waveform.
3A and 3B are waveform diagrams showing current waveforms of a switch element and a rectifier diode of a smoothing circuit, respectively.
4 is a circuit diagram showing another example of the light emitting diode illumination device.

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

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. Rather, the intention is not to limit the invention to the particular forms disclosed, but rather, the invention includes all modifications, equivalents and substitutions that are consistent with the spirit of the invention as defined by the claims.

It will be appreciated that when an element such as a layer, region or substrate is referred to as being present on another element "on," it may be directly on the other element or there may be an intermediate element in between .

Although the terms first, second, etc. may be used to describe various elements, components, regions, layers and / or regions, such elements, components, regions, layers and / And should not be limited by these terms.

Fig. 1 shows an example of a light emitting diode lighting circuit. This lighting circuit has an insulation type using a transformer T1 and has a secondary-side detection constant current control system for power factor correction, and shows an example corresponding to a wide-range power supply input.

That is, the AC power source 100 V or 220 V is connected to the power source 10, and the rectifier circuit 20 is connected to the power source 10. The rectifier circuit 20 can use a full-wave rectifier circuit using a bridge diode.

The small-capacity capacitor C1 for absorbing the switching current may be connected to the rectifying circuit 20 and the full-wave rectifying voltage is generated by the rectifying circuit 20 and the capacitor C1.

The rectifier circuit 20 is connected to a transformer T1. The transformer T1 may be a fly-back transformer.

Such a transformer T1 has a primary winding P1 and an auxiliary winding P2 on the primary side and an output winding S1 on the secondary side.

The switch element Q1 is connected to the main winding line P1 of the transformer T1 and is connected in series to the full-wave rectification voltage line together with the source current detecting resistor R7 so as to be connected in series to the main winding of the transformer T1 P1. ≪ / RTI >

Here, a MOSFET device can be used as the switching device Q1.

A snubber circuit 50 may be provided on the main winding line P1 of the transformer T1. The snubber circuit 50 is connected to the source current detecting resistor R7 through the switch element Q1, Is connected to the first input of the current comparator OP1, which is compared with the comparison voltage generated by the control circuit 70 described later.

The snubber circuit 50 suppresses the transient voltage generated when the inductance load of the winding is turned on / off by using a relay or a semiconductor switching element (transistor, FET, thyristor, etc.) It is a circuit used for.

The snubber circuit 50 includes a capacitor C4 connected in parallel to each other, a resistor R6 and a diode D1.

Voltage-drop resistors R8 and R9 are connected to the auxiliary winding P2 of the transformer T1. The zero current comparator OP2 compares the reference voltage Ref1 connected to the zero current comparator OP2 through the voltage dividing resistors R8 and R9 to determine the time at which the release of the magnetic energy of the transformer T1 is completed Is detected.

This zero current comparator OP2 is connected to the S terminal of the element FF1 which generates the drive pulse of the switch element Q1.

In this way, the voltage-dividing resistors R8 and R9, the zero current comparator OP2 and the reference voltage Ref1 can act as the detecting section 60 that detects the time when the magnetic energy emission of the transformer T1 is completed.

The secondary side of the transformer T1 generates a DC output voltage from the output winding S1 through the smoothing circuit 30 composed of the rectifier diode D2 and the smoothing capacitor C6, And is connected to the light emitting portion 40 including the light emitting diode 41.

That is, the smoothing circuit 30 is connected to the anode of the light emitting diode 41, and the detection resistor R10 for detecting the current flowing through the light emitting portion 40 is connected to the cathode of the light emitting diode 41 Lt; / RTI >

At this time, the voltage detected by the detection resistor R10 is compared with the reference voltage Ref2 by the output current comparator OP3, and the current according to the result is compared with the voltage of the bleeder resistor R11 and the series of the porter couplers PC1 And is returned to the primary side by the circuit.

That is, through the first feedback circuit 80 including the detection resistor R10, the output current comparator OP3, the reference voltage Ref2, the bleeder resistor R11, and the porter coupler PC1, And is fed back to the second feedback circuit 90 on the primary side coupled to the first feedback circuit 80.

As described above, the current signal is input to the receiving portion of the coupler PC1 of the second feedback circuit 90 on the primary side through the transmitting portion of the coupler PC1 of the first feedback circuit 80. [

The error signal thus returned to the primary side becomes a current signal at the receiving portion of the coupler PC1 and is connected to the constant current source 91 and the smoothing capacitor C5 COMP voltage 101 and is connected to the first input terminal of the multiplier 92 do.

With this configuration, the error signal becomes almost a DC voltage, and is limited to a band of about 20 Hz.

On the other hand, voltage limiting circuits 100, 200 and 300 are provided between the rectifying circuit 20 and the primary side of the transformer T1.

The voltage limiting circuits 100, 200, and 300 include a voltage detecting unit 100 that generates a detection signal of the output voltage of the rectifying circuit 20, an average voltage detecting unit 200 that generates an average value of the output voltages of the rectifying circuit 20 And a voltage restricting unit 300 for dividing the average value and limiting the maximum value of the detection signal through the voltage detecting unit 100.

The voltage detecting unit 100 generates the detection voltage by dividing the output voltage of the rectifying circuit 20 by the voltage dividing resistor and reducing the noise through the noise absorbing capacitor C2.

The average voltage detector 200 smoothes the output voltage of the rectifier circuit 20 through the resistor R3 and the capacitor C3 to generate an average voltage at the capacitor C3 terminal.

The voltage limiting unit 300 limits the voltage by dividing the average value thus generated and connecting the detection voltage using the transistor Q2.

Thus, the full-wave rectification detection voltage 102, which is the output through the voltage limiter 300, is limited in the upper part by the PNP transistor Q2 and is connected to the second input terminal of the multiplier 92. [

The multiplier 92 multiplies the COMP voltage 101 by the full wave rectification detection voltage 102 and is connected to the second input terminal of the peak current comparator OP1 as a comparison signal so that the detection voltage of the source current detection resistor R7 The element FF1 for generating the drive pulse of the switch element Q1 is reset at the moment when the comparison signal is exceeded and the switch element Q1 is turned off.

2A and 2B show the full-wave rectification detection waveform 102. In FIG. FIG. 2A shows the case where the input voltage is 220 Vac, FIG. 2B shows the case where the input voltage is 100 Vac, and the sine waveform of the full-wave rectification is limited to a specific voltage.

Here, due to the operation of the average voltage detector 200, the limiting voltage follows the proportional voltage according to the magnitude of the input voltage, so that it has a trapezoidal shape similar to each other. Therefore, the ratio of suppressing the maximum voltage value can be maintained.

3A and 3B respectively show the current waveform of the switching element Q1 and the waveform of the rectifying diode D2 of the smoothing circuit 30. In Fig. Here, a MOSFET is used as the switching element Q1.

As shown in the figure, it can be seen that the peak value of the source current of the MOSFET which is the switching element Q1 becomes an envelope of trapezoidal shape.

The peak value of the current is multiplied by the turns ratio P1 / S1 and becomes the peak value of the secondary side diode D2 current in each switching period of the switching element Q1. Therefore, the envelope of the current of the diode D2 Likewise become trapezoidal.

This triangular wave is smoothed by the smoothing circuit 30 and supplied to the light emitting diode 41 of the light emitting portion 40.

A normal power factor correcting device can obtain a value close to the power factor of 1, but the regulated value of the harmonic current of the power source which is deeply related to the power factor is a power factor of 0.7 to 0.9 It is possible to comply with it, and there is room as a power factor value.

On the other hand, a conventional power factor correction device requires a design having a certain allowance for electrical and magnetic characteristics at an input voltage peak portion that gives a maximum current, and a factor that determines the size of the inductor or flyback transformer do.

Concretely, the current flowing in the primary winding at the peak portion of the input voltage also becomes a peak value, and a thick winding having a margin for the current density is required. Further, the magnetic flux density generated in the core in proportion to this current It was necessary to select a larger core size so as to have a certain margin. It is also necessary to select a large-capacity component for the bridge diode and the MOSFET which are the primary side serial power components through which the primary peak current flows.

However, the lighting apparatus described above suppresses the maximum value of the primary current within a range allowed by harmonics of the power factor or the power source, so that it becomes unnecessary to use various components with large capacity.

Such an illumination device can be applied to a power factor correcting circuit of an input full-wave rectification reference type. In the case of Fig. 1, an insulation type is shown, but the modification can be applied to a non-insulation type.

In the case of the insulation method as shown in Fig. 1, it is also applicable to a configuration in which the detection signal is changed to return the current and / or voltage of the output.

Further, the present invention is also applicable to a primary-side detection system in which various proposed secondary-side information of the transformer T1 is estimated by applying a specific calculation from specific current and voltage information on the primary side .

Such a lighting apparatus can have a simple circuit configuration, and it is not necessary to use various components having a large capacity, so that the size of the lighting circuit can be reduced.

In addition, in addition, the ripple of the output current can be smoothened to improve the quality of the light emitting diode illumination device.

Actually, when the power factor is set to 0.9 with respect to 1 in the circuit as shown in Fig. 1, the primary current peak current is lowered to 80% when the same power is converted, and a margin is given to the transformer or the like.

Further, the ripple of the output current rises from the minimum value to the maximum value from 23% to 35%, and planarization can be achieved.

FIG. 4 shows another example of a light emitting diode lighting apparatus, which differs from the example of FIG. 1 in that it is a single power supply input rather than a wide-range power supply input.

In this case, in the voltage limiter circuit, the average voltage detector 200 shown in FIG. 1 is not provided, and the voltage limiter 310 is not provided with the same voltage limiter as the zener diode ZD1 as a means for limiting the maximum value of the full- Device is different.

1 except that the voltage limiting circuit includes a voltage detecting section 100 for generating a detection signal of the output voltage of the rectifying circuit 20 and a voltage detecting section 100 for detecting the voltage of the detection signal by the voltage detecting section 100. In other words, And a voltage limiting unit 310 for limiting the maximum value.

In this case, the upper portion of the full-wave rectification detection voltage can be suppressed by a specific voltage with a fixed value for a single power supply input.

It should be noted that other voltage limiting elements or voltage limiting circuits may be used in place of the zener diode ZD1.

In addition, the same elements as those described in the example of Fig. 1 can be applied to the parts not described.

It should be noted that the embodiments of the present invention disclosed in the present specification and drawings are only illustrative of specific examples for the purpose of understanding and are not intended to limit the scope of the present invention. It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments disclosed herein.

10: AC power supply 20: rectifier circuit
30: Smoothing circuit 40:
50: Snubber circuit 60: Detector
70: control circuit 80: first feedback circuit
90: second feedback circuit 100:
200: average voltage detector 300, 310: voltage limiter

Claims (12)

A rectifying circuit for rectifying an AC voltage input from an AC power source;
A transformer having a main winding wire and an auxiliary winding on the primary side and an output winding on the secondary side;
A series circuit including a switching element connected to an output terminal of the rectifying circuit and connected to a main winding of the transformer;
A light emitting unit connected to the output winding of the transformer and including a plurality of light emitting diodes;
A feedback circuit for returning an error of a current flowing through the light emitting portion to a primary side;
A voltage detection unit which is located between the rectification circuit and the transformer and which limits the maximum value of the output voltage of the rectification circuit and generates a detection signal of the output voltage of the rectification circuit; A voltage limiter circuit including an average voltage detector and a voltage limiter for dividing the average value and limiting a maximum value of the detection signal; And
And a control circuit controlling the switch element and connected to the feedback circuit and the voltage limiting circuit to control the timing of the switch element according to the limited voltage. delete The light emitting diode illuminating apparatus according to claim 1, wherein the voltage detecting section generates a detection voltage by dividing an output voltage of the rectifying circuit by a voltage dividing resistor and reducing a noise through a noise absorbing capacitor. The light emitting diode lighting apparatus according to claim 1, wherein the average voltage detecting unit smoothes an output voltage of the rectifying circuit through a resistor and a capacitor to generate an average voltage at the capacitor terminal. The light emitting diode illumination device according to claim 1, wherein the voltage restricting portion limits the voltage by dividing the average value and connecting the detection voltage using a transistor. The light emitting diode lighting apparatus according to claim 1, wherein a smoothing circuit is provided between the output winding of the transformer and the light emitting portion. 2. The apparatus of claim 1,
A first feedback circuit for detecting an error of a current flowing through the light emitting unit; And
And a second feedback circuit coupled to the first feedback circuit and supplying the current feedback to the control circuit as an error signal. 8. The apparatus of claim 7, wherein the first feedback circuit comprises:
A detection resistor for detecting a voltage flowing in the light emitting diode;
Reference voltage;
And an output current comparator for comparing the voltage by the detection resistor and a reference voltage. The light emitting diode lighting apparatus according to claim 7, wherein the second feedback circuit is connected to the voltage limiting circuit and the control circuit through a multiplier. The voltage limiting circuit according to claim 1,
A voltage detector for generating a detection signal of an output voltage of the rectifying circuit; And
And a voltage limiter for limiting a maximum value of the detection signal. 11. The light emitting diode lighting apparatus according to claim 10, wherein the voltage restricting portion includes a zener diode. The light emitting diode lighting apparatus of claim 1, further comprising a snubber circuit between the voltage limiting circuit and the transformer.

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