KR101198408B1 - AC Direct Connection Type LED Lighting Device Having Function of Flicker Reduction and Improving Light Efficiency - Google Patents

Abstract

The present invention minimizes the peak depth of the output ripple waveform of the AC direct-connected LED luminaire, and operates the LED array into a plurality of LED groups by parallel connection, thereby operating within the AC direct-connected array. By providing at least one group within a linear range of LED current, the present invention provides an AC direct type LED lighting device having flicker reduction and light efficiency improvement to minimize light flicker and increase light efficiency.
To this end, the present invention, in the AC direct type LED lighting device having a full-wave rectifier bridge diode and a constant current controller in the AC power source, a plurality of LED arrays connected to the LED array connected to at least two AC power, each LED array Is divided into groups according to the number of LEDs and propagates by two first and second LED groups which are turned on by receiving an input current whose linearity is compensated from a Valley Fill device for each group, and the bridge diode. Compensating the peak current of the rectified pulse wave waveform by the charging and discharging operation, thereby adjusting the peak value of the current to apply the average current (Average Current) to the first and second LED group Characterized in that configured.

Description

AC direct connection type LED lighting device having function of flicker reduction and improving light efficiency

The present invention minimizes the flicker occurring in the AC direct drive LED lighting device, and has flicker reduction and light efficiency improvement functions to prevent the light efficiency reduction in the AC direct type according to the characteristics of the LED. It relates to an AC direct type LED lighting device.

In general, LED lighting equipment is to adjust the brightness of the LED by changing the current supplied based on a constant voltage, or by using a current control method to sense a current to flow a constant current, it is possible to adjust the brightness of the LED It is widely used as a major lighting device.

Generally, LED lighting equipment can be classified into a DC power supply method using a DC output power using an SMPS (AC / DC Coverter), and an AC direct type method using a high frequency switching or a pulse current directly by inputting AC power. Recently, as demands for improvement of weight and space constraints have increased among the requirements of LED lighting equipment, it is a trend to prefer an AC direct type method to a DC power method using an SMPS that is heavy and takes a little space.

Based on this market situation, the wide range of use of AC direct-type lighting equipment has led to two problems. Firstly, flicker occurs due to the use of AC power. Second, DC LEDs have a problem of deterioration of light efficiency, which is fundamentally generated due to their own characteristics according to current vs. brightness and voltage vs. brightness.

In particular, the biggest problem in AC direct-connected LED lighting equipment is the generation of flicker, which is caused by the brightness change caused by the periodic current change of the AC power source. The distinction is difficult due to optical illusion, but in the case of a device such as a camera, the screen is displayed in a superimposed form at about 24 frames per second, and the shadow area according to the current change appears as a stripe form.

This flicker phenomenon can be remarkably reduced in inverse proportion to the distance. In general, when the user uses a general lighting, the flicker phenomenon is not noticeable to the naked eye. In addition to feeling eye fatigue, there is a possibility of adversely affecting the mental state of the user due to the surrounding indoor condition exposed by the flicker.

On the other hand, Figures 1a to 1d shows a circuit diagram of a conventional general AC direct-type lighting equipment.

In the conventional AC direct-connected lighting apparatus shown in FIG. 1A, a plurality of LEDs are connected in series to an AC power source, and a resistor R1 is connected in series between the plurality of LEDs and the AC power source. Current control is achieved through

In the conventional AC direct-connected luminaire shown in FIG. 1B, an LED array in which a plurality of LEDs are arranged in series connected in a forward direction and an LED array in which a plurality of LEDs are connected in series in a reverse direction are connected in parallel to an AC power source, and the parallel The resistor R2 is connected in series between the connected LED array and the AC power supply.

In the conventional AC direct-connected lighting apparatus shown in FIG. 1C, a bridge diode BD is connected between an AC power supply and a plurality of LEDs, and a resistor R3 is connected in series between the plurality of LEDs and the AC power supply. Each LED is turned on by using a pulse wave voltage rectified through the diode BD.

In the conventional AC direct-connected lighting apparatus illustrated in FIG. 1D, a plurality of LEDs are connected in series to an AC power source, and a constant current source is connected between the plurality of LEDs and the AC power source so that constant current control can be performed through the constant current source. Consists of.

 On the other hand, Figure 2 is a diagram showing a full-wave rectified voltage waveform and the current waveform in the AC direct-connected lighting device of Figures 1a to 1d.

As shown in FIG. 2, the current waveform operates after the constant voltage and within the peak current range according to the voltage waveform, which is about 1.8 times compared with the average average / peak waveform. It is designed to operate using current range of.

3 is a view showing an actual measurement of the output waveform characteristics and the flicker phenomenon according to the conventional LED.

That is, in case of AC direct type, the same power is used as compared to DC type lighting equipment using DC average current like SMPS, but due to saturation of LED light emission characteristic in peak current region, There is a problem that the light efficiency is not good, and when the LED having such a light emitting property is applied as an AC direct-connected lighting device, the flicker phenomenon is inevitably generated.

In addition, the second problem that can be raised is that the DC LED is due to its own characteristics according to the current vs. light intensity, voltage vs. light intensity degradation, which is a nominal level of current vs. light intensity and voltage vs. light intensity characteristics of the DC LED. (Nominal level) or less has a linearity, but if the level is higher than it does not have a linearity has a characteristic that is saturated.

4A to 4C are graphs comparing power vs. luminous efficiency of LEDs manufactured by predetermined LED manufacturers.

As shown in Figures 4a to 4d, the light efficiency reduction characteristics according to the characteristics of the DC LED is more prominent in the AC direct type that must be repeated the average value and peak current periodically, the same power efficiency for each LED manufacturer Although there are differences in terms of light efficiency by manufacturers, a problem arises that the light efficiency is about 20% less than 10%.

Accordingly, there is an urgent need for a breakthrough method that can minimize the light efficiency deterioration due to the characteristics of the DC LED and minimize the flicker phenomenon of the AC direct-type lighting equipment.

Accordingly, the present invention has been made to solve the above-mentioned conventional problems, and an object thereof is to minimize the depth of the output ripple waveform of the AC direct-connected LED lighting device, and to provide a plurality of LED arrays by parallel connection. By dividing the LED into groups of LEDs, at least one group within the AC direct array operates within a linear range of LED current, thereby reducing flicker and increasing light efficiency while minimizing flicker. It is to provide AC direct LED lighting equipment with improved functions.

According to the present invention for achieving the above object, in an AC direct type LED lighting device having a bridge diode and a constant current controller for full-wave rectification in an AC power source, at least two or more LED array connected to the AC power source to the AC power source; And each of the LED arrays divided into groups according to the number of LEDs, and for each group, two first and second LED groups, each of which is turned on by receiving input linearly compensated input current from a Valley Fill device, By compensating for the peak current of the pulse wave waveform rectified by the bridge diode by the charging and discharging operation, the peak current of the current is adjusted to adjust the average current to the first and second LED groups. The present invention provides an AC direct type LED lighting device having flicker reduction and light efficiency improvement, which is configured to include a valid valley fill device.

According to the present invention as described above, in the AC direct-connected LED lighting equipment by the addition of a valley fill and the addition of a plurality of groups by the parallel connection of the LED array, and by combining the switching technology, the radio wave using a valley fill It is possible to minimize and alleviate the flicker phenomenon of AC direct type by adjusting the crest value of rectified waveform and operating LEDs composed of a plurality of parallel connection groups separately for each group. It has the effect of increasing the light efficiency that can be lowered by the characteristics rather.

1a to 1d is a view showing a circuit diagram for a conventional general AC direct-type lighting equipment,
2 is a diagram showing a voltage waveform and a current waveform according to the full-wave rectified in the AC direct-connected lighting device of Figure 1a to 1d,
3 is a view showing the actual measurement of the output waveform characteristics and the flicker phenomenon according to the conventional LED,
4A to 4C are graphs comparing power vs. luminous efficiency of LEDs manufactured by predetermined LED manufacturers;
5 is a view showing a circuit configuration of an AC direct type LED lighting device having a flicker reduction and light efficiency improvement function according to a first embodiment of the present invention;
6 is a view showing a circuit configuration of an AC direct type LED lighting device with flicker reduction and light efficiency improvement function according to a second embodiment of the present invention;
7 is a view showing a circuit configuration of an AC direct type LED lighting device having a flicker reduction and light efficiency improvement function according to a third embodiment of the present invention;
8 is a view illustrating an example of a specific circuit configuration of a valley fill device applied to the present invention;
9 is a diagram illustrating an output voltage waveform shown in the valley fill device of FIG. 8;
10 is a view showing a current waveform of each group of a plurality of LED groups according to a preferred embodiment of the present invention,
11A and 11B are views illustrating actual waveforms and flicker states of LEDs respectively appearing in the first group and the second group when the LED group is divided into first and second groups according to a preferred embodiment of the present invention. .

Hereinafter, the present invention configured as described above will be described in detail with reference to the accompanying drawings for each embodiment.

FIG. 5 is a diagram illustrating a circuit configuration of an AC direct type LED lighting device having flicker reduction and light efficiency improvement functions according to a first embodiment of the present invention.

As shown in FIG. 5, according to the first embodiment of the present invention, an AC power source, a bridge diode 10, a Valley Fill device 20, a first LED group Group1, and a second LED group ( Group2), a switching controller consisting of a level detector Inv and a control switch SW in the second LED group Group2, and a constant current source 30.

The bridge diode 10 is connected in series between the AC power supply and the valley fill device 20. The bridge diode 10 converts a sine wave of 60 Hz input from the AC power source into a pulse wave of 120 Hz.

The valley fill device 20 is connected in series between the bridge diode 10 and the first LED group Group1, and is full-wave rectified through the bridge diode 10 through a charging and discharging operation of a current. By adjusting and supplying the peak value of the peak current of the zero crossing portion that occurs periodically in the pulse wave of 120 Hz, the compensation of the input current is performed to approach the DC average current. Outputs a current.

That is, the valley-filling device 20 adjusts the ratio between average current and peak current in the AC direct-connected structure to be minimized, so that each LED current has a LED linearity (Nominal DC). Average current) to minimize the degradation of luminous efficiency due to the LED's own characteristics.

The first LED group Group1 and the second LED group Group2 include at least two or more LED arrays in which a plurality of LEDs are connected in series (two LED arrays are applied in the first embodiment of the present invention). In a state in which each LED array is connected in parallel to the AC power supply, a node of a part in which the number of a plurality of LEDs constituting each LED array can be divided into equal numbers (that is, 10 LEDs are connected to one LED array) In this case, it is possible to form by parallel connection of five nodes, which are equally divided by five.

That is, the LED array (LED 1-1) (LED 1-2) corresponding to the upper side of the parallel connected node portion is divided into a first LED group (Group1), LED array (LED 2) corresponding to the lower side Is divided into a second LED group (Group2).

On the other hand, the LED array portion of the second array group Group2 is not connected to the LED, and has a switching controller composed of a level detector Inv and a control switch SW.

The level detector Inv is connected to a parallel connection terminal of the first LED group Group1 and the second LED group Group2 to generate an output signal according to the level of current supplied to each LED group Group1, 2. The control switch SW is connected between at least one array of the second LED group Group2 and is configured by a switching circuit such as a switching transistor to be controlled by an output signal of the level detector Inv and to be switched on. By performing the on / off operation, the input current can operate within the linearity range to prevent attenuation of the luminous efficiency.

That is, the control switch SW is normally switched on so that the LED of the first LED group Groip1 is turned on, and is automatically switched off when a state in which the voltage reaches a specific level is detected by the level detector Inv. It is to be connected to the current path of the first LED group and the second LED group.

Each of the LED arrays LED 1-1 and LED 1-2 included in the first LED group Group1 includes peak current compensation from the valley fill device 20, the level detector Inv, and a control switch SW. By switching control according to the input current level by the switching control unit consisting of a), since the current close to the DC average current is applied to turn on, the flicker phenomenon by the AC power source hardly occurs.

On the other hand, the LED array LED 2 included in the second LED group Group 2 has a peak current including a part of the current passing through the first LED group Group 1, so that it can be seen in the AC direct type. A flicker phenomenon corresponding to the peak of the current pulse wave (Depth) may appear.

The constant current source 30 is connected between the second LED group Group2 and the AC power source, and controls the current flowing through the second LED group Group2 with a constant current.

Next, FIG. 6 is a diagram illustrating a circuit configuration of an AC direct type LED lighting device having flicker reduction and light efficiency improvement functions according to a second embodiment of the present invention. Like reference numerals refer to like elements, and detailed descriptions thereof will be omitted.

As shown in FIG. 6, in the second embodiment of the present invention, an AC power source, a bridge diode 10, a Valley Fill device 20, a first LED group Group1, and a second LED group Group2 are illustrated. And a switching control unit including a level detector Inv and a control switch SW, and a constant current source 30.

The first LED group Group1 and the second LED group Group2 according to the second embodiment of the present invention are arranged in a forward LED array in which a plurality of LEDs are connected in series in a forward direction, and a plurality of LEDs are connected in series in a reverse direction. At least two bidirectional coupled AC LED arrays of a parallel connection type in which the reverse LED arrays are connected in parallel to an AC power supply (in the first embodiment of the present invention, two AC LED arrays are illustrated), and AC The connected nodes are connected to each other by connecting the plurality of bidirectional coupled AC LED arrays to each other in parallel with each other, and connecting the nodes of the portions where the number of the LEDs constituting each LED array can be divided into the same number. The LED array (AC LED 1-1, AC LED 1-2) of the first LED group (Group1) is separated on the upper side and the LED array (AC LED 2) of the second LED group (Group2) on the lower side, separated by a boundary. It can be formed as.

The switching control unit including the level detector Inv and the control switch SW is connected to one of the bidirectional coupled AC LED arrays in the second LED group Group2 to perform switching control according to the current level change of the input current. This allows the input current to operate within the linearity range.

The first LED group Group1 according to the second embodiment of the present invention is the same as the first embodiment, each of the LED array (AC LED 1-1, AC LED 1-2) included in the first LED group (Group1) Is a current close to the DC average current through the peak current compensation from the valley-filling device 20 and switching control according to the input current level by the switching controller consisting of the level detector Inv and the control switch SW. When applied and turned on, flickering by AC power hardly occurs.

On the other hand, the LED array AC LED 2 included in the second LED group Group2 has a peak current including a part of the current passing through the first LED group Group1, so that it can be seen in the AC direct type. A flicker phenomenon corresponding to the peak of the current pulse wave (Depth) may appear.

Next, FIG. 7 is a diagram illustrating a circuit configuration of an AC direct type LED lighting apparatus having flicker reduction and light efficiency improvement functions according to a third embodiment of the present invention. The first embodiment of the present invention shown in FIG. Like reference numerals refer to like elements, and detailed descriptions thereof will be omitted.

As shown in FIG. 7, in the third embodiment of the present invention, an AC power supply, a bridge diode 10, a valley fill device 20, a first LED group Group1, and a second LED group Group2 are illustrated. And a switching control unit consisting of a level detector Inv and a control switch SW in the second LED group Group2, and a resistor R2. Unlike the first embodiment of the present invention, a constant current source is not connected. Has no structure.

Here, the resistor R2 is connected to each LED array of the second LED group Group2, and serves to control the current flowing through the LED array with a constant current.

On the other hand, in the third embodiment of the present invention, the resistor R2 is applied as the constant current controller, but the present invention is not limited thereto, and the combination structure of the constant current control transistor, the constant current control capacitor and the resistor, the combination of the transistor and the resistor. Of course, any constant current controller capable of performing the control of the constant current, such as a structure, can be applied.

In the third embodiment of the present invention, as in the first embodiment, each LED array LED 1-1 and LED 1-2 included in the first LED group Group 1 has a peak from the valley fill device 20. Flickering by the AC power supply through the current compensation and the switching control according to the input current level by the switching controller consisting of the level detector Inv and the control switch SW, the lamp is turned on by receiving a current close to the DC average current. The phenomenon rarely occurs.

In addition, the LED array LED 2 included in the second LED group Group2 has a peak current including a part of the current passing through the first LED group Group1, so that it can be seen in the AC direct type. A flicker phenomenon corresponding to the peak of the pulse wave may appear.

Next, FIG. 8 is a view showing in detail an example of a circuit configuration of the valley fill device applied to each of the first to third embodiments of the present invention.

As shown in FIG. 8, in the valley-filling device applied to the present invention, a first solid capacitor SC1 and a first diode D1 are connected in series between both output terminals of the bridge diode BD. In addition, the third diode (D3) and the second solid capacitor (SC2) are connected in series between the two output terminals, respectively, the connection terminal of the first solid capacitor (SC1) and the first diode (D1), The second diode D2 and the resistor R1 are respectively connected between the third diode D3 and the connection terminal of the second solid capacitor SC2.

As the first and second solid capacitors SC1 and SC2 perform charging and discharging of the full-wave rectified input current by an operation according to a current level change of the first to third diodes D1, D2, and D3. By compensating the peak current by adjusting the peak value between the peak current and the average current, a current close to the DC average current is applied to the first LED group Group1.

FIG. 9 is a diagram illustrating an output voltage waveform shown in the valley fill device of FIG. 8. As shown in the drawing, the output voltage waveform is changed according to the capacity of a capacitor used, Therefore, the value can be selected.

By doing so, the ratio between the peak current and the average current actually used can be minimized, and the average current value can be increased, thereby improving the luminous efficiency and reducing the flicker. After application, flicker improvement (i.e. flicker reduction) effect can be reduced from about 100% to 40%, and if the luminous efficiency of LED has up to 20% loss, it will be 100% efficiency improvement and up to about 10% luminous efficiency. The loss can be reduced.

In addition, in order to solve the service life limitation and size problem caused by the use of the existing electrolytic capacitors, the valley-filling device 30 is replaced with a solid capacitor to extend the service life and to reduce size and thermal characteristics. Make it less susceptible to

Meanwhile, the valley fill device 30 applied to the present invention has a circuit element and a connection structure as illustrated in FIG. 8, but the present invention is not limited thereto, and the valley of any structure that is variously configured and applied at present. The fill device can be applied to any number, and only the capacitor constituting the valley fill device enables the application of a solid capacitor.

10 is a view showing a current waveform of each group of a plurality of LED groups according to a preferred embodiment of the present invention, Figures 11a and 11b is divided into a first group and a second group of LED groups according to a preferred embodiment of the present invention In this case, the measurement waveforms and flicker states of the LEDs respectively appearing in the first group and the second group are illustrated.

That is, as shown in FIGS. 10, 11A, and 11B, a plurality of LED arrays are provided for the AC power source, and parallel nodes are connected by connecting intermediate nodes in parallel to divide the plurality of LED arrays into the same number. By forming two LED groups at the boundary, substantially the current of each LED group can be classified so that the first LED group can operate within a linear range, so that there is no attenuation of luminous efficiency.

In the first to third embodiments of the present invention shown in FIGS. 5, 6, and 7, the level detector Inv and the control switch SW are provided at any one of the LED array portions of the second LED group Group2. As configured, the LEDs are not connected, and the number of LEDs included in the first LED group Group1 is at least twice as large as the number of LEDs included in the second LED group Group2. Accordingly, since the number of LEDs of the first LED group Group1 using the linear current increases, the flicker phenomenon can be reduced, and the luminous efficiency can be increased.

Meanwhile, in the first to third embodiments of the present invention, in order to form two first and second LED groups, two LED arrays may be applied as a plurality, respectively, but at least three LED arrays may be applied. Although it is possible to configure a single switching control unit consisting of a level detector (Inv) and a control switch (SW), it is not limited to this, it is also possible to configure at least two or more corresponding to the increased arrangement of the LED array. Do.

Here, increasing and adjusting the number of LED arrays is performed when the phase for equalizing the power of each half cycle is 45 degrees (90 degrees on both sides), which is 0.707 times when the number of LEDs is configured by RMS voltage. The same brightness can be controlled every half cycle.

While specific embodiments of the invention have been described and shown above, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention. Such modified embodiments should not be understood individually from the technical idea and viewpoint of the present invention, but should be regarded as belonging to the claims attached hereto.

10: bridge diode, 20: valley fill device,
30: constant current source, Group 1, Group 2: LED group,
R1, R2: Resistance, Inv: Level Detector,
SW: control switch, SC1, SC2: solid capacitor,
D1, D2, D3: Diode.

Claims (7)

In an AC direct type LED lighting device having a bridge diode for rectifying rectification and a constant current controller in an AC power source,
Inputs that have linearity compensation from a Valley Fill device for each group by connecting LED arrays connected with a plurality of LEDs to at least two AC power sources, and classifying each LED array into groups according to the number of LEDs. Two groups of first and second LEDs which are turned on in response to a current; And
By compensating the peak current of the pulse wave waveform full-wave rectified by the bridge diode by the charging and discharging operation, the peak current of the current is adjusted to apply an average current to the first and second LED groups. Valley Fill device;
Including;
The LED is not connected to any one of the LED arrays in the second LED group, and the switching of the current paths of the first LED group and the second LED group is performed according to the change of the current level of the input current, so that the input current is linear. A switching control unit for operating within a range is connected, the switching control unit,
A level detector connected to a parallel connection terminal of the first LED group and the second LED group to generate an output signal according to a level change of a current supplied to each LED group, and connected between any one array of the second LED group And a control switch configured to perform switching control by the output signal of the level detector to allow an input current to operate within a linearity range. The method of claim 1,
The first and second LED groups each have the same number of LEDs constituting each of the LED arrays, with at least two or more LED arrays having a plurality of LEDs connected in series, connected in parallel to the AC power supply. Flicker reduction, characterized in that the number of nodes that can be divided by the number of parallel connection to each other, the upper LED array of the parallel connected node is divided into a first LED group, and the lower LED array is divided into a second LED group And AC direct-attached LED luminaires with improved light efficiency. The method of claim 1,
The first and second LED groups may include at least two bidirectional coupled AC LED arrays having a forward-connected LED array and a reverse-connected LED array of a plurality of LEDs and connected in parallel to each other, and constitute a plurality of AC LED arrays. By connecting the nodes of the parts where the number of LEDs can be divided into the same number each other, the AC LED array of the first LED group on the upper side and the AC LED array of the second LED group on the lower side with the connected nodes as boundaries. AC direct type LED lighting equipment with flicker reduction and light efficiency improvement, characterized in that it can be formed separately. delete delete The method of claim 1,
In the valley fill device, a first capacitor and a first diode are connected in series between both output terminals of the bridge diode, and a third diode and a second capacitor are connected in series between the two output terminals, respectively, and the first capacitor is connected. And a second diode and a resistor are connected between the connection terminal of the first diode and the connection terminal of the third diode and the second capacitor, respectively. device. The method according to claim 6,
The first and second capacitors AC direct type LED lighting device with a flicker reduction and light efficiency improvement, characterized in that consisting of a solid capacitor (Solid Capacitor).

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