KR101270711B1 - Light emitting diode lighting apparatus - Google Patents

Abstract

PURPOSE: An LED lighting device is provided to use an AC power source and not to use an AC/DC converter, thereby reducing the weight and size. CONSTITUTION: An LED lighting device comprises a rectifier circuit which is connected to an AC power source; a first LED group which has at lest one LED; a second LED group which is serially connected to the first LED group; a first switch which opens or closes the connections of connection terminals and earth terminals of the first LED group and the second LED group; and a second switch which opens or closes the connection of a terminal and an earth terminal of the second LED group.

Description

LED lighting apparatus

The present invention relates to an LED lighting apparatus, and more particularly, to an LED lighting apparatus using an AC power source, which improves flicker.

An LED (Light Emitting Diode) is a semiconductor device that emits light when a voltage is applied in the forward direction. The light emitting principle of the LED uses an electroluminescent effect, and its lifetime is relatively long compared to incandescent lamps. The emission color varies depending on the material used and can emit light from the ultraviolet region to the visible and infrared region. Due to the advantages of these LEDs, LEDs are used in various fields, and in particular, the brightness of LEDs is adjusted by changing the current supplied based on a constant voltage to adjust the brightness, or by using a current control method that senses the current and flows a constant current. It is widely used as a lighting device because it can adjust.

In general, LED lighting apparatuses can be broadly classified into a DC power supply method using a DC output power using an AC / DC converter, and an AC direct type method using a high frequency switching or a pulse current directly by inputting AC power. Recently, as the demand for improvement in weight, space, and price of LED lighting apparatuses increases, many studies on AC direct type schemes in which a driving circuit is simpler than DC power schemes that are heavy and occupy relatively more space are being conducted. However, there is a problem that flicker occurs when using the AC power. This flickering is caused by the change in brightness caused by the periodic current change of the AC power. When the human eye is over 24 Hz, it is difficult to distinguish due to optical illusion, but in the case of a device such as a camera, the screen is about 24 frames per second. Displayed in a superimposed form, the shadowed area due to the current change occurs in the form of stripes.

Such flickering may be significantly inversely proportional to the distance. In general lighting, the user may not notice the naked eye, but when the user uses a lighting device that is flickering for a long time. In addition to feeling of eye fatigue, there is a possibility of adversely affecting the psychological state of the user due to the surrounding indoor condition exposed by blinking. Therefore, it is necessary to improve the flicker in order to be applied to the LED lighting fixture using the AC power in various fields.

The problem to be solved by the present invention is to provide an LED lighting that improves the flicker phenomenon using an AC power source.

AC power direct-connected LED (Light Emitting Diode) lighting device according to an aspect of the present invention is connected to an AC power source, and receives a current from the AC power through the rectifier circuit and the rectifier circuit consisting of a bridge diode for full-wave rectification. And a first LED group including at least one LED, wherein the first LED group is configured to supply current to the first LED group in a section in which the first LED group does not receive current from the AC power source. The power supply is connected.

The auxiliary power is charged by the AC power in a section in which the first LED group is supplied with current from the AC power, and the first LED group is discharged in a section in which no current is supplied from the AC power. Current can be supplied to a group of LEDs.

The auxiliary power source may be a capacitor connected in parallel to the first LED group.

The lighting device is a second LED group consisting of at least one LED, connected in series with the first LED group, a first opening and closing the connection between the connection terminal and the ground terminal of the first LED group and the second LED group A second switch may further include a switch and a second switch configured to open and close a connection between a terminal of the second LED group and a ground terminal opposite to a connection end of the second LED group with the first LED group.

The first LED group and the second LED group may be connected in series through a blocking diode that prevents current from flowing in the second LED group toward the first LED group.

The first switch and the second switch may be sequentially opened and closed according to a cyclic change in the magnitude of the alternating current applied by the alternating current power source to control the current flowing through the first LED group and the second LED group. .

The number of LEDs constituting the first LED group and the number of LEDs constituting the second LED group may be different from each other.

The lighting device is a second LED group consisting of at least one LED, connected in parallel with the first LED group and the AC power source, a first switch for opening and closing the connection between the first LED group and the ground terminal and the first It may further include a second switch for opening and closing the connection between the terminal of the 2 LED group and the ground terminal.

The first switch and the second switch may be controlled according to a change in amplitude of an AC voltage applied by the AC power source.

One end of the first LED group and the second LED group connected in parallel may be connected through a blocking diode.

By using AC power as the power source of LED lighting equipment, it is possible to reduce the weight and size of lighting equipment without using AC / DC converter, and to improve the flicker that can occur when using AC power. Problems that occur can be solved. In addition, by controlling the number of LED groups and the number of LEDs belonging to each LED group, it is possible to effectively control the luminous flux, power factor and distortion of the lighting fixture.

1 shows an example of a circuit configuration of an AC direct type LED lighting fixture.
FIG. 2 shows the voltage VAC across the AC power and the current IAC flowing when AC power is applied to the circuit of FIG.
3 and 4 illustrate AC current waveforms and waveforms of each LED group obtained when the circuit of FIG. 1 is implemented.
5 is an example of a luminaire circuit configuration according to another embodiment of the present invention.
6 is a graph showing the current waveform of the main part in the embodiment of FIG.
7 is an example of a luminaire circuit configuration according to another embodiment of the present invention.
8 is a graph showing the current waveform of the main part in the embodiment of FIG.

As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail below. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, .

In addition, the components shown in the embodiments of the present invention are shown independently to represent different characteristic functions, which does not mean that each component is composed of separate hardware or software constituent units. That is, each constituent unit is included in each constituent unit for convenience of explanation, and at least two constituent units of the constituent units may be combined to form one constituent unit, or one constituent unit may be divided into a plurality of constituent units to perform a function. The integrated embodiments and separate embodiments of the components are also included within the scope of the present invention, unless they depart from the essence of the present invention.

In addition, some of the components are not essential components to perform essential functions in the present invention, but may be optional components only to improve performance. The present invention can be implemented only with components essential for realizing the essence of the present invention, except for the components used for the performance improvement, and can be implemented by only including the essential components except the optional components used for performance improvement Are also included in the scope of the present invention.

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

1 shows an example of a circuit configuration of an AC direct type LED lighting fixture.

LED lighting may be composed of a rectifier circuit and at least one LED group connected to an AC power source to rectify the AC power source. The LED group again includes at least one LED.

In the example of FIG. 1, the diode bridge composed of D1, D2, D3, and D4 is an example of a rectifier circuit. The diode bridge shown in FIG. 1 is a full-wave rectifier circuit and receives a pulse of AC power. GR1, GR2, and GR3 in FIG. 1 each represent a group of LEDs and include at least one LED. Figure 1 is an example of the case consisting of three LED groups of GR1, GR2 and GR3 This is just an embodiment, and for the convenience of the description below will be described as an example LED luminaire having three LED groups as an example The present invention is not limited thereto, and there is no particular limitation on the number of LED groups constituting the LED light.

In the example of FIG. 1, the switches SW1, SW2, and SW3 for controlling the current flowing through the respective LED groups are connected to each of the GR1, GR2, and GR3. SW1, SW2, and SW3 may be controlled to be shorted in sequence according to the magnitude of each AC voltage by the switching control circuit, or each switch may be controlled to open or short in accordance with the magnitude of the current flowing through the sensing current flowing through the switch. have. According to an exemplary embodiment, the control unit may be controlled to open / short sequentially according to time after the zero crossing detection of the AC voltage.

FIG. 2 shows the voltage VAC across the AC power and the current IAC flowing when AC power is applied to the circuit of FIG. The waveform of the current may be changed according to the control of the three LED groups GR1, GR2, and GR3 and the SW1, SW2, and SW3 that control the current flowing through each LED group. The example of FIG. 2 illustrates a case in which the IAC subtracts a stepped waveform having three magnitudes according to the control of each switch.

The luminaire according to the embodiment of the present invention, the total number of LED groups, the number of LEDs constituting each LED group, the distortion of the current IAC through the control of the switch for controlling the current of each LED group (Total Harmonic Distortion, THD) I _THD and lighting power factor can be adjusted. However, in the IAC waveform of FIG. 2, there is a section in which IAC = 0, which causes discontinuity of current flowing in each LED group of the luminaire, resulting in flicker of the luminaire.

3 and 4 illustrate AC current waveforms and waveforms of each LED group obtained when the circuit of FIG. 1 is implemented. In FIGS. 3 and 4, the ovals indicated by dotted lines indicate sections in which currents flowing through the LED groups are discontinuous, resulting in flickering of the LED lighting. Hereinafter, another embodiment of the present invention will be described with a luminaire having improved flickering.

5 is an example of a luminaire circuit configuration according to another embodiment of the present invention.

The circuit of FIG. 5 has the distinction that an auxiliary power source is connected to the circuit of FIG. 1 and each LED group and that a blocking diode is included to prevent the reverse flow of current between the LED groups.

In the circuit of FIG. 5, the switch operation is controlled by sensing a current of each switch. Switch control can be controlled by the various methods described above.

Referring to the operation of the circuit of Figure 5 step by step as follows.

When the VAC voltage rises and becomes larger than the threshold voltage Vfa of GR1, SW1 is short-circuited, the current of SW1 flows to GR1, and the LED of GR1 emits light. When the VAC voltage rises further and becomes larger than the threshold voltage Vfb of GR1 + GR2, a current flows in SW2, the current of SW2 flows to GR1 and GR2, and the LEDs of GR1 and GR2 emit light. When SW2 is shorted and a current flows, SW1 is opened.

When the VAC voltage rises further and becomes larger than the threshold voltage Vfc of GR1 + GR2 + GR3, current flows to SW3, and the current of SW3 flows to GR1, GR2, GR3, and the LEDs of GR1, GR2, and GR3 emit light. When is open, SW2 is opened through the current sensing signal.

When the VAC voltage passes the peak and falls below the threshold voltage Vfc of GR1 + GR2 + GR3, SW3 opens and SW2 shorts again, so that the current in SW2 flows through GR1 and GR2, and the LEDs of GR1 and GR2 emit light.

When the VAC voltage is lower than the threshold voltage Vfb of GR1 + GR2, SW2 is opened and SW1 is shorted again, so that the current of SW1 flows through GR1, and the LED of GR1 emits light.

When the VAC voltage is lower than the threshold voltage Vfa of GR1, SW1 is open and SW1, SW2, and SW3 are all open. At this time, regardless of whether the SW1 is shorted / opened, current does not flow in the SW1. In this case, according to the exemplary embodiment, the short state may be maintained without opening the SW1. At this time, at least one of the auxiliary power supplies Vsub1, Vsub2, and Vsub3 connected in parallel to GR1, GR2, and GR3 is operated to supply power to the LED group connected in parallel with the LED to emit LEDs of the corresponding LED group.

After that, when the VAC voltage rises again and becomes larger than the threshold voltage Vfa of GR1, SW1 is short-circuited (when SW1 is not opened and the short-circuit state is maintained as in the other embodiment described above, control to short-circuit SW1 is unnecessary). The current flows to GR1, the LED of GR1 emits light, and the above-described steps are repeated.

According to the operation of the circuit described above, when the switches are all open and power is not supplied to each LED group, current may flow to the LED group by the auxiliary power to emit LEDs of the corresponding LED group. Can improve flickering.

In the example of FIG. 5, the auxiliary power sources Vsub1, Vsub2, and Vsub3 are controlled in connection with the operation control of SW1, SW2, and SW3, and may be configured as independent power sources or dependent power sources according to embodiments. The auxiliary power supply may simply be configured as a passive element. In one embodiment, the auxiliary power supply may be configured as a capacitor. When an auxiliary power source consists of a capacitor, the capacitor is charged by the voltage across the LED group when current flows in a group of LEDs connected in parallel with it, and starts discharging if no current flows in that LED group. Current can flow through the LED group.

In the circuit of FIG. 5, D8 and D9 are blocking diodes for preventing reverse voltages of the auxiliary power supplies Vsub2 and Vsub3. As described above, the number of LED groups and the number of LEDs constituting each LED group may be variously configured in consideration of power factor, luminous flux, and distortion I _THD . The number of LEDs belonging to each LED group may be the same or different, and may have a structure that increases or decreases sequentially according to an embodiment, and the number of LEDs constituting each LED group to minimize power loss in a switch. Can be determined to be proportional to the AC voltage.

For example, if the number of LEDs is GR1>GR2> GR3, a relatively high luminous flux can be obtained, but the power factor decreases and I _THD is increased. Each switch current can be set to I_SW1 = <I_SW2 = <I_SW3 to improve I _THD .

6 is a waveform of the voltage across the VAC and the current flowing through the VAC when the above-described operation is performed by implementing the circuit of FIG. 5, the waveform of the current I_SW1 flowing through SW1 and the current I_GR1 flowing through GR1, and the current I_SW2 flowing through SW2; It is a graph which shows the waveform of the current I_GR2 which flows in GR2, the waveform of the current I_SW3 which flows in SW3, and the current I_GR3 which flows in GR3.

As can be seen in Figure 6, I_GR1, I_GR2 and I_GR3 has a non-zero value even in the open interval (I_SW1 = 0, I_SW2 = 0 I_SW3 = 0) all the switch, as shown by the dotted oval have. That is, it is possible to know the current flow in each LED group, and as a result, the LED of the LED group always maintains the emission state to improve flickering.

7 is an example of a luminaire circuit configuration according to another embodiment of the present invention.

The circuit of FIG. 7 is a structure in which each LED group is connected in parallel with each other. The circuit diagram of FIG. 7 shows an example in which the auxiliary power source is constituted by a capacitor, and the number of LEDs constituting each group GR1, GR2, and GR3 is varied.

In the circuit of FIG. 7, as in the previous embodiment, the SWs control a current flowing through each LED group and include a constant current source. The circuit of FIG. 7 may operate as follows when AC power is applied.

When the VAC voltage rises and becomes larger than the threshold voltage Vf1 of GR1, SW1 is short-circuited, the current I_SW1 of SW1 flows to the LED of GR1, and C1 is charged by the voltage across GR1.

When the VAC voltage rises further and becomes larger than the threshold voltage Vf2 of GR2, SW2 is short-circuited, the current I_SW2 of SW2 flows to GR2, and C2 is charged by the voltage across GR2. When current flows in SW2, SW1 is opened through the current sensing signal. When SW1 is open, the charged C1 is discharged and C1 supplies current so that the LED of GR1 can maintain the light emitting state.

When the VAC voltage rises further and becomes larger than the threshold voltage Vf3 of GR3, SW3 is short-circuited, the current I_SW3 of SW3 flows to the LED of GR3, and C3 is charged by the voltage across GR3. When current flows in SW3, SW2 is opened through the current sensing signal. However, when SW2 is opened, the charged C2 is discharged and C2 supplies current so that the LED of GR2 can maintain the light emitting state.

When the VAC voltage passes the peak and falls below the threshold voltage Vf3 of GR3, SW3 is opened and SW2 is shorted again to charge C2 while supplying current to the LED of GR2 from AC power. When SW3 is open, the LED current of GR3 is supplied from C3.

When the VAC voltage is lower than the threshold voltage Vf2 of GR2, SW2 is opened and SW1 is shorted again. SW1 opens when the VAC voltage is lower than the threshold voltage Vf1 of GR1.

That is, when a switch of a LED group is short-circuited, the LED group receives current from a power source with VAC power and emits light, and charges a capacitor used as an auxiliary power source. If the switch in the group is open, the charged capacitor will start discharging while the switch is short-circuited to supply current to the LED group so that the current always flows through the LED group.

D8 and D9 are blocking diodes for preventing reverse voltages of C2 and C3. In the embodiment described with reference to FIG. 5 as in the example of FIG. 5, the number of LED groups and the number of LEDs constituting each LED group may be variously configured in consideration of power factor, luminous flux, and distortion I _THD . . The number of LEDs belonging to each LED group may be the same or different, and may have a structure that increases or decreases sequentially according to an embodiment, and the number of LEDs constituting each LED group to minimize power loss in a switch. Can be determined to be proportional to the AC voltage. As an example of implementation, the number of LEDs constituting GR1 and GR2 may be determined in consideration of power factor and distortion, and the number of LEDs constituting GR3 may be determined to be proportional to the AC voltage. Each switch current can be set to I_SW1 = <I_SW2 = <I_SW3 to improve I _THD .

FIG. 8 illustrates the waveform of the voltage across the VAC and the current flowing through the VAC when the above-described operation is performed by implementing the circuit of FIG. 7, the waveform of the current I_SW1 flowing through SW1 and the current I_GR1 flowing through GR1, and the current I_SW2 flowing through SW2; It is a graph which shows the waveform of the current I_GR2 which flows in GR2, the waveform of the current I_SW3 which flows in SW3, and the current I_GR3 which flows in GR3.

As can be seen in Figure 8, I_GR1, I_GR2 and I_GR3 has a non-zero value even in the interval (I_SW1 = 0, I_SW2 = 0 I_SW3 = 0) in all the switches open, such as the section indicated by the dotted oval. have. That is, it is possible to know the current flow in each LED group, and as a result, the LED of the LED group always maintains the emission state to improve flickering. In addition, by adjusting the number of LED groups, the number of LEDs constituting the LED group, and the current flowing through the switch, it is possible to selectively adjust / improve the power factor, luminous flux, distortion of the lighting fixture.

The above-described embodiments include examples of various aspects. While it is not possible to describe every possible combination for expressing various aspects, one of ordinary skill in the art will recognize that other combinations are possible. Accordingly, it is intended that the invention include all alternatives, modifications and variations that fall within the scope of the following claims.

Claims (10)

In the AC power direct-connected LED (Light Emitting Diode) lighting equipment,
A rectifier circuit connected to an AC power source and configured of a full-wave rectifying bridge diode; And
A first LED group composed of at least one LED, the current being supplied from the AC power supply through the rectifier circuit;
A second LED group consisting of at least one LED, connected in series with the first LED group;
A first switch for opening and closing a connection between the connection terminal and the ground terminal of the first LED group and the second LED group; And
And a second switch configured to open and close a connection between a terminal of the second LED group and a ground terminal opposite to a connection end of the second LED group with the first LED group.
A first capacitor (capacitor) for supplying current to the first LED group in a section in which the first LED group is not supplied with current from the AC power source is connected in parallel to the first LED group,
Direct connection to an AC power supply, characterized in that a second capacitor (capacitor) for supplying current to the second LED group in a section in which the second LED group does not receive current from the AC power supply is connected in parallel to the second LED group. Type LED lighting equipment. The method according to claim 1,
The first capacitor is charged by the AC power in a section in which the first LED group is supplied with current from the AC power supply, and is discharged in a section in which the first LED group does not receive current from the AC power supply. AC power direct type LED lighting device, characterized in that the supply of current to the LED group. delete delete The method according to claim 1,
And the first LED group and the second LED group are connected in series through a blocking diode that prevents current from flowing in the direction of the first LED group from the second LED group. The method according to claim 1,
The first switch and the second switch are sequentially opened and closed according to a cyclic change in the magnitude of the alternating current applied by the AC power, to control the current flowing through the first LED group and the second LED group. AC power direct type LED lighting equipment. The method according to claim 1,
The number of LEDs constituting the first LED group and the number of LEDs constituting the second LED group is different from each other, the AC power direct type LED lighting device. In the AC power direct-connected LED (Light Emitting Diode) lighting equipment,
A rectifier circuit connected to an AC power source and configured of a full-wave rectifying bridge diode;
A first LED group composed of at least one LED, the current being supplied from the AC power supply through the rectifier circuit;
A second LED group consisting of at least one LED connected in parallel with the first LED group and the AC power source;
A first switch for opening and closing a connection between the first LED group and a ground terminal; And
And a second switch configured to open and close a connection between the terminal of the second LED group and the ground terminal.
A first capacitor (capacitor) for supplying current to the first LED group in a section in which the first LED group is not supplied with current from the AC power source is connected in parallel to the first LED group,
Direct connection to an AC power supply, characterized in that a second capacitor (capacitor) for supplying current to the second LED group in a section in which the second LED group does not receive current from the AC power supply is connected in parallel to the second LED group. Type LED lighting equipment. The method of claim 8
And the first switch and the second switch are controlled according to a change in amplitude of an AC voltage applied by the AC power. The method of claim 8,
One end of the first LED group and the second LED group connected in parallel is connected via the blocking diode, AC power direct type LED lighting device.

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