KR101357636B1 - A high efficiency direct driving circuit for LEDs with flickerless function - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct-connected LED driving circuit, which can design a switching element with a relatively small capacity, and prevents inrush current of the switching element and prevents flicker by being consumed in an LED array without bypassing charged charges. The present invention relates to a high efficiency direct-connected LED driving circuit with flicker elimination function that eliminates and prevents a decrease in efficiency.
The present invention relates to a direct-connected LED driving circuit for driving an input AC power source with a full-wave rectified voltage via a bridge diode (BD), the capacitor for removing flicker at the anode and cathode terminals of the LED array. Are connected to both LEDs to form a group of LEDs, and a rectifying diode is connected in a forward direction between a cathode of a single LED array and an anode of an adjacent LED array so that each of the plurality of LED arrays is connected in series, and a cathode terminal of the LED array is connected. And a switching element connected in parallel between a cathode terminal of an adjacent LED array connected to the LED array through a rectifying diode, and a rectifier connected to the LED array and a cathode of the LED array and a flicker removal capacitor connected in parallel thereto. The diode is removed from the + terminal of the bridge diode according to the 'on' and 'off' operation of the switching element. Provided are high efficiency direct-connected LED driving circuits and embodiments thereof having a flicker elimination function, wherein the provided current is configured to be bypassed or provided as a current of the LED array.

Description

High efficiency direct driving circuit for LEDs with flickerless function

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct-type LED driving circuit, which can design a switching element with a relatively small capacity, and prevents inrush current of the switching element and prevents flicker by being consumed in an LED array without bypassing charged charges. The present invention relates to a high efficiency direct-connected LED driving circuit with flicker elimination function that eliminates and prevents a decrease in efficiency.

As a driving circuit for using a light emitting diode as an illumination, there is a direct-connected LED driving circuit system for full-wave rectifying an AC commercial power supply and providing it directly to a plurality of light emitting diodes. Since the LED driving circuit according to this method does not use a complicated circuit configuration such as a witching mode power supply (SMPS), it is widely used because of the high reliability of the driving circuit due to the aging of the circuit elements. The direct-connected LED driving circuit for a conventional commercial power supply drives by switching a plurality of LED arrays according to the magnitude of the input voltage in order to increase the lighting efficiency against the fluctuation of the full-wave rectified voltage.

However, in the plurality of light emitting diodes driven in this manner, a flicker phenomenon, which is twice the commercial voltage frequency, occurs due to the variation of the full-wave rectified voltage provided from the bridge diode BD, and also the dynamic resistance of the LED array is increased. (dynamic resistance) causes the LED array not to be turned on, so that the variation of the overall brightness appears periodically and repeatedly.

As a background art of the present invention, there is a high efficiency serial string LED driver technology of the individual LED control function of US Patent No. 7,649,326 B2 shown in FIG. This technique allows a constant current source to produce a constant current with high efficiency over a wide range of output voltages and provide the current to one end of the string LED in series, the other end of the string being connected to ground through a resistor. The voltage present on the resistor is fed back to the constant current source as the amount of current in the series string from which the constant current source provides a constant current over a wide range of output voltages. A field effect transistor is connected in parallel to each of the LEDs in the string and the gate of each field effect transistor is driven by a pulse width modulation control signal provided from a level shift gate driver. By the field effect transistors, LEDs may be bypassed or provided with current to emit light and modulate the field effect transistor duty ratios to smoothly change the brightness of each LED over its entire range. However, according to this technique, when the voltage provided to the constant current source is a wave full-wave rectified, flicker occurs twice the frequency of commercial power, and the LED is not turned on, thereby driving the LED at maximum brightness. There is a restriction that can not be.

As another background technology for the present invention, there is a technology related to the LED driving circuit and the method of EP 2 288 234 A1 shown in FIG. 2. The technology features an LED driver with a plurality of LED arrays, one or more split diodes, a power supply, a driver, one or more pairs of switch pairs, and a voltage detector. Each LED array consists of a plurality of LEDs connected in series, a split diode is provided between adjacent LED arrays, and the power supply unit is connected to an external power source to provide DC pulse current power. The driver receives a DC pulsation voltage to provide a constant current to the LED array, and the voltage detector changes the electrical connection of the LED array by opening or shorting a pair of switches. However, this technology also has a limitation in driving efficiency of the LED because the voltage provided to the LED array is a DC pulse current supply, which generates twice the flicker frequency of the commercial power frequency and a section in which the LED is not lit.

Another background technology of the present invention is the light emitting diode lighting apparatus of the Republic of Korea Patent No. 10-0942234 by the same applicant of the present invention. This technique is connected in parallel to an AC power source, as shown in FIG. 3, arrayed into a plurality of LED arrays of at least one LED, the plurality of LED arrays arranged in series, and between each LED array. And LED arrays each having tabs at cathode terminals of the last LED array; A reference voltage source for generating a reference voltage; A light emitting diode having a high efficiency, high efficiency and low harmonic characteristics in a wide input voltage range, including a switching unit for efficiently controlling the peak current for each LED array based on a reference voltage according to the increase and decrease of the AC input voltage It features a lighting device. However, this technology also has a flicker that is twice the frequency of commercial power, and the LED is not lit, causing the LED to not be driven at maximum brightness and efficiency.

US 7649326 B2 EP 2288234 A1 KR 10-0942234 B1 US 20100194298 A1 KR 10-2007-0000963 A KR 10-2009-0060878 A KR 10-2008-0032090 A KR 10-2009-0010269 A

According to the present invention, a plurality of light emitting diodes driven by a direct type LED driving circuit method have a flicker phenomenon corresponding to twice the commercial voltage frequency generated by a change in the full-wave rectified voltage provided from the bridge diode BD. An object of the present invention is to provide a high efficiency direct-connected LED driving circuit having a removed flicker removal function.

In addition, an object of the present invention is to provide a high efficiency direct-connected LED driving circuit having a flicker removal function that enables the switching device to be designed with a relatively small capacity by preventing the inrush current of the switching device.

In addition, the present invention is to solve the problem to provide a high-efficiency direct-connect LED drive circuit with a flicker removal function to prevent the degradation of the efficiency by allowing the charge in the capacitor to be consumed in the LED array without bypassing the flicker removal It is a task.

The present invention to solve the above problems,

In a direct-connected LED driving circuit for driving LEDs with a full-wave rectified voltage through an input AC power supply via a bridge diode (BD), one or more LED arrays are connected in series, and the anode and cathode of a single LED array are connected. Both terminals of the flicker removal capacitor are connected to the terminal to form a group of LEDs, and a rectifying diode is connected in the forward direction between the cathode of the single LED array and the anode of the adjacent LED array, so that each of the plurality of LED arrays is connected in series. A switching element is connected in parallel between the cathode terminal of the LED array and the cathode terminal of an adjacent LED array connected to the LED array through a rectifying diode, and the flicker removing capacitor and the LED array connected in parallel therewith. The rectifier diode connected to the cathode is dependent on the 'on' and 'off' operation of the switching element. The current provided from the + terminal of the diode bridge and provides by-pass or high-efficiency direct hookup of flicker elimination function, characterized in that configured to provide current to the LED array, LED drive circuit and those embodiments as solving means of the problem.

According to the high efficiency direct connection type LED drive circuit of the flicker removal function of this invention,

There is a technical effect of eliminating a flicker phenomenon, which is twice the commercial voltage frequency generated in a plurality of light emitting diodes driven by a direct LED driving circuit method.

In addition, the present invention has the effect of enabling the switching device to be designed with a relatively small capacity by preventing the inrush current of the switching device. In addition, the present invention provides an effect of preventing the degradation of efficiency by allowing the charges charged in the capacitor to be consumed in the LED array without bypassing the flicker.

Figure 1 is a background technology configuration of the high efficiency serial string LED driver technology of the individual LED control function
2 is a view showing the configuration of a LED driving circuit and a method thereof as another background technology.
3 is a view illustrating the configuration of a light emitting diode lighting apparatus as another background technology.
Figure 4 shows the basic configuration of the direct-attached LED drive circuit and the flicker removal mechanism.
5 shows VI characteristics and dynamic resistance of light emitting diodes.
6 shows the relationship between voltage and current for the basic configuration of a direct LED driving circuit.
FIG. 7 illustrates one embodiment of a direct LED drive circuit and flicker removal configuration for driving a plurality of LED arrays.
8 shows the relationship of the current to the direct-connect LED drive circuit and the flicker removal configuration.
Figure 9 is a basic configuration and current flow of the high efficiency direct-connected LED driving circuit of the flicker removal function of the present invention
Figure 10 is a first embodiment of a high efficiency direct-attached LED driving circuit of the flicker removal function of the present invention
Figure 11 is a second embodiment of a high efficiency direct-connected LED driving circuit of the flicker removal function of the present invention

The following merely illustrates the principles of the invention. Accordingly, those skilled in the art will be able to devise various apparatuses which, although not explicitly described or shown herein, embody the principles of the invention and are included in the concept and scope of the invention. Furthermore, all of the conditional terms and embodiments listed herein are, in principle, intended only for the purpose of enabling understanding of the concepts of the present invention, and are not intended to be limiting in any way to the specifically listed embodiments and conditions .

The above objects, features and advantages will become more apparent from the following detailed description in conjunction with the accompanying drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

4 shows the basic configuration of the direct-attached LED drive circuit and the flicker removal mechanism. The input AC power is provided to the LED array at full-wave rectified voltage via the bridge diode (BD). The LED array is provided by connecting a plurality of LEDs in series and by connecting a current limiting circuit in series to limit the current flowing in the LED array, a constant current against the variation of the full-wave rectified voltage provided from the bridge diode (BD) To the LED array. At this time, a flicker phenomenon corresponding to twice the commercial voltage frequency occurs according to the variation of the full-wave rectified voltage provided from the bridge diode BD, and also due to the dynamic resistance of the LED array. The LED array has a section that does not turn on, so that the change in overall brightness is repeated periodically. This flicker phenomenon is not visible to the naked eye, but when used as an illumination for industrial lighting or an image processing system, it affects the image quality of the image and also lowers the luminous efficiency of the LED array. As a countermeasure, the flicker phenomenon can be improved by connecting a capacitor in parallel with the LED array as shown in FIG. 4.

5 shows the VI characteristics and dynamic resistance of the light emitting diode. The light emitting diode converts a current according to a voltage applied in a forward direction to light based on a single PN junction. The light emitting diode is a voltage through which a hole and free electrons can pass through the depletion layer of the PN junction, and a current starts to flow when a voltage of Vf1 of 0.6 to 0.7 V or more is applied, and according to the voltage applied to the PN junction. The amount of current increases. Therefore, the dynamic resistance of the diode has a very large resistance value because the slope of the tangent to the VI characteristic curve is close to horizontal near Vf1, and the dynamic resistance decreases because the vertical resistance increases as the applied voltage increases. Has The graph on the right side of FIG. 5 is an example of the VI characteristics of a conventional lighting LED. Since the lighting LED is implemented by connecting a plurality of LEDs in series, the forward voltage Vfn is relatively higher than that of a single junction LED. Has For example, in the case of an AC 220 V 50 Watt light emitting diode, since 84 light emitting diodes are connected in series, the forward voltage Vfn becomes 0.6 VX 84 ≒ 50 V. Therefore, when the voltage applied to the AC 220 V 50 Watt lighting LED is 50 V or less, the lighting LED is not turned on as a blocking state even though it is a forward bias.

6 shows the relationship of voltage and current to the basic configuration of the direct-connected LED driving circuit. As described above, when a full-wave rectified voltage is provided to the LED array in the direct-connected LED driving circuit, flicker, which is twice the commercial voltage frequency, occurs, and the forward voltage and the dynamic resistance of the LED array are also increased. As a result, a section in which the LED array is not turned on is generated, and the variation of the overall brightness appears periodically and repeatedly. FIG. 6A shows the current IL with respect to the forward voltage Vf of the LED array when the full-wave rectified voltage V is provided to the LED array. In the direct-connected LED driving circuit, the current IL of the LED array starts to flow at a phase angle above the forward voltage Vf due to the influence of dynamic resistance near the forward voltage Vf. In the section, it can be seen that section d occurs where the LED array is not turned on. When the capacitors are connected in parallel with the LED array in parallel with the LED driving circuit as illustrated in FIG. 4, the current IL of the LED array is continuously discharged by charging and discharging of the capacitor as shown in FIG. As a result, the flicker phenomenon and the section in which the LED array is not lit can be eliminated.

7 illustrates one embodiment of a direct LED drive circuit and flicker removal configuration for driving a plurality of LED arrays. As described in the background art of the present specification, a direct LED driving circuit for a conventional commercial power supply drives a plurality of LED arrays by switching the plurality of LED arrays according to the magnitude of the input voltage in order to increase the lighting efficiency against the variation of the full-wave rectified voltage. The operational relationship to the circuit of FIG. 7 is as follows. Power provided from a commercial AC power source is full-wave rectified through a bridge diode and provided to a direct LED driving circuit. A plurality of LED arrays G1 to G4 are connected in series to the + and-terminals of the bridge diode, and a current limit circuit is connected to one end of the plurality of LED arrays to provide a constant current to the plurality of LED arrays. At this time, switching elements SW1 to SW3 are connected to each of the LED arrays after the first LED array connected to the + terminal of the bridge diode in parallel to supply or bypass power from the bridge diode to the LED array. The switching element is driven by a comparator composed of OP1, OP2, and OP3, and compares the applied voltage between the reference voltage source and the LED array to 'on' the switching element when the applied voltage between the LED array is smaller than the reference voltage, When the applied voltage between the LED array is large, the switching element is 'off' to control the driving of the LED array according to the magnitude of the input voltage. In the example of FIG. 7, when the input voltage is small, the comparator composed of OP1, OP2, and OP3 turns on SW1, SW2, and SW3 so that only the LED array G1 is turned on, and SW1 is 'off' as the input voltage is gradually increased. LED arrays G1 and G2 light up. Then, when SW2 is 'off', the LED arrays G1, G2, and G3 are turned on. In the maximum voltage range, all the LED arrays G1 to G4 are turned on because the SW1 to SW3 are 'off'. Subsequently, in the decreasing period of the input voltage, the switching elements SW1 to SW3 are 'on' in the reverse order of lighting, so the LED arrays are turned off in the reverse order of lighting.

Capacitors C1 to C4 may be connected in parallel to the respective LED arrays G1 to G4 to remove flicker as described in FIGS. 4 to 6 with respect to the direct LED driving circuit. However, the above configuration can eliminate flicker but causes a problem of efficiency to be described later.

FIG. 8 shows the working relationship of the current to the direct-connected LED drive circuit and flicker removal configuration of FIG. 8 shows the flow of current when the switching element SW1 transitions from an 'off' state to an 'on' state with respect to the point where the LED arrays G1 and G2 are connected to the circuit of FIG. 7. To show. When the switching element SW1 connected in parallel to the LED array G2 is 'on' in response to a change in the input voltage, the current IS1 bypassed through the switching element SW1 is in accordance with Kirchhoff's current law.

IS1 = IG1-IG2 + IC1 + IC2

. Here, since the LED array G2 and the capacitor C2 are shorted by the SW1, the electric charges charged in the capacitor C2 flow through the switching element SW1 as IC2, and a large inrush current flows instantaneously. On the other hand, the switching element SW1 not only needs to be designed with a large capacity unnecessarily, but also provides a path for charging the current supplied from the power supply to the capacitor C2 and discharging it through the switching element SW1, causing a decrease in efficiency. This phenomenon occurs in each of the switching elements connected in parallel with each LED array in a direct LED driving circuit driving a plurality of LED arrays in which capacitors are connected in parallel, causing a further increase in inrush current and deterioration of efficiency.

According to the present invention, when the switching elements are 'on', the switching elements are consumed in the LED array without bypassing the charge charged in the capacitor, thereby preventing the inrush current of the switching element, eliminating flicker, and preventing the deterioration of efficiency. It provides high efficiency direct connection LED driving circuit.

Figure 9 shows the basic configuration and current flow of the high efficiency direct-connected LED drive circuit of the flicker removal function of the present invention.

In the high efficiency direct-connected LED driving circuit of the flicker elimination function of the present invention, one or more LED arrays G1 to G4 are connected in series, and rectifying diodes D1, D2, D3, and D4 are connected in series between the respective LED arrays in a forward direction. do. In addition, a current limit circuit is connected in series to one end of the plurality of LED arrays to provide a constant current to the plurality of LED arrays. Each of the LED arrays has capacitors C1 to C4 for preventing flicker in parallel and a driving unit includes one LED array and a capacitor connected in parallel to the one LED array. At this time, switching elements SW1 to SW3 are connected to each of the LED arrays after the first LED array connected to the + terminal of the power supply in parallel to supply or bypass power from the bridge diode to the LED array. The switching element switches between a cathode terminal of one LED array and a connection point of a capacitor connected in parallel to the one LED array from a cathode terminal of a next LED array and a connection point of a capacitor connected in parallel to the LED array of the next stage. When the voltage of the LED array cathode terminal to be switched is lower than the reference voltage by comparing the applied voltage between the reference voltage source and the switched LED array cathode terminal, the switching element is 'on', and the voltage of the LED array cathode terminal to be switched than the reference voltage is In large cases, the switching element is 'off' to control the driving of the LED array according to the magnitude of the input voltage.

9 shows the flow of current when the switching element SW1 transitions from an 'off' state to an 'on' state with respect to the point where the LED arrays G1 and G2 are connected. When the switching element SW1 connected in parallel to the LED array G2 is 'on' in response to a change in the input voltage, the current IS1 bypassed through the switching element SW1 is in accordance with Kirchhoff's current law.

IS1 = IG1-IG2 + IC1

. Here, when SW1 is 'on', the charge charged in the capacitor C2 is blocked by D1, and all of the IC2 flows through the LED array G2 and is used as lighting energy.

A general description of the above configuration is as follows.

In the high efficiency direct-connected LED driving circuit of the flicker removal function of the present invention, one or more LED arrays are connected in series, and both ends of the flicker removal capacitor are connected to the anode and the cathode terminals of a single LED array. Rectifying diodes are connected in a forward direction to form one LED group and between a cathode of a single LED array and an anode of an adjacent LED array so that each of the plurality of LED arrays is connected in series. A switching element is connected in parallel between the cathode terminal of the LED array and the cathode terminal of an adjacent LED array connected to the LED array through a rectifying diode. The rectifier diode connected to the LED array, the flicker elimination capacitor connected in parallel thereto, and the cathode of the LED array has a current supplied from the + terminal of the bridge diode according to 'on' and 'off' operation of the switching element. Passed or provided by the current of the LED array. At this time, the LED array connected to the + terminal of the bridge diode for the first time and the flicker elimination capacitor connected in parallel are configured to be always lit regardless of the input condition by eliminating the switching element.

Therefore, according to the high efficiency direct-connected LED driving circuit of the flicker elimination function of the present invention, the switching element can be designed with a relatively small capacity, and the inrush current of the switching element is reduced by being consumed in the LED array without bypassing the charged charge. It can prevent, remove flicker, and prevent the fall of efficiency.

Figure 10 shows a first embodiment of the high efficiency direct-connected LED drive circuit of the flicker removal function of the present invention.

Power provided from a commercial AC power source is full-wave rectified through a bridge diode and provided to a direct LED driving circuit. One end of the plurality of LED arrays is connected in series to the + and-terminals of the bridge diode, and a current limit circuit is connected to the other end of the plurality of LED arrays to provide a constant current to the plurality of LED arrays.

Both ends of the flicker-removing capacitor are connected to the anode and cathode terminals of a single LED array to form a group of LEDs, and a rectifying diode is forward between the cathode of the single LED array and the anode of the adjacent LED array. Each of the plurality of LED arrays is connected in series. A switching element is connected in parallel between the cathode terminal of the LED array and the cathode terminal of an adjacent LED array connected to the LED array through a rectifying diode. The rectifier diode connected to the LED array, the flicker elimination capacitor connected in parallel thereto, and the cathode of the LED array has a current supplied from the + terminal of the bridge diode according to 'on' and 'off' operation of the switching element. Passed or provided by the current of the LED array. At this time, the LED array connected to the + terminal of the bridge diode for the first time and the flicker elimination capacitor connected in parallel are configured to be always lit regardless of the input condition by eliminating the switching element.

The switching element is driven by a comparator composed of OP1, OP2, and OP3, and compares the applied voltage of the cathode terminal of the LED array to be switched with the reference voltage source, when the applied voltage of the LED array cathode terminal is smaller than the reference voltage. When the applied voltage of the LED array cathode terminal is larger than the reference voltage, the switch is turned off to control the driving of the LED array according to the magnitude of the input voltage.

In the example of FIG. 10, when the input voltage is small, the comparator consisting of OP1, OP2, and OP3 turns on SW1, SW2, and SW3 so that only the LED array G1 connected in parallel to the flicker elimination capacitor C1 is lit through the current limiting circuit CLC0. As the input voltage is gradually increased, SW1 is 'off' so that the LED arrays G1 connected in parallel to C1 and G2 connected in parallel to C2 are turned on through the current limiting circuit CLC0. Then, when SW2 is 'off', the LED arrays G1, G2, and G3 are turned on through the current limiting circuit CLC0, and in the maximum voltage range, all the LED arrays G1 to G4 are turned off through the current limiting circuit CLC0. Lights up. Subsequently, in the decreasing period of the input voltage, the switching elements SW1 to SW3 are 'on' in the reverse order of lighting, so the LED arrays are turned off in the reverse order of lighting.

Therefore, the high efficiency direct-connect type LED driving circuit having the flicker removal function of the first embodiment of the present invention prevents the inrush current of the switching element and eliminates the flicker by causing the LED array to be consumed without bypassing the charge charged in the flicker removal capacitor. In addition, the degradation of efficiency can be prevented.

Figure 11 shows a second embodiment of the high efficiency direct-connected LED drive circuit of the flicker removal function of the present invention. The high efficiency direct-connected LED driving circuit having the flicker removal function of the second embodiment of the present invention is configured to perform tracking of the input voltage even when the capacitance of the above-described flicker removal capacitor is set to a large value.

Power supplied from a commercial AC power source is full-wave rectified via the bridge diode and provided to the direct-connected LED driving circuit via the rectifying diode D0. A plurality of LED arrays are connected in series at the + terminal of the bridge diode and one end of the plurality of LED arrays is connected to the-terminal of the bridge diode through a current limit circuit to provide a constant current to the plurality of LED arrays. do.

Both ends of the flicker-removing capacitor are connected to the anode and cathode terminals of a single LED array to form a group of LEDs, and a rectifying diode is forward between the cathode of the single LED array and the anode of the adjacent LED array. Each of the plurality of LED arrays is connected in series. A switching element is connected in parallel between the cathode terminal of the LED array and the cathode terminal of an adjacent LED array connected to the LED array through a rectifying diode. The rectifier diode connected to the LED array, the flicker elimination capacitor connected in parallel thereto, and the cathode of the LED array has a current supplied from the + terminal of the bridge diode according to 'on' and 'off' operation of the switching element. Passed or provided by the current of the LED array. At this time, the LED array connected to the + terminal of the bridge diode for the first time and the flicker elimination capacitor connected in parallel are configured to be turned on by excluding a switching element.

The switching element is driven by a comparator composed of OP1, OP2, and OP3. The switching element divides the voltage provided by the diode bridge for each switching voltage and compares it with a reference voltage source, and when the switching voltage divided by the reference voltage is smaller than the switching element ' on 'and' off 'the switching element when the divided voltage is greater than the reference voltage, thereby controlling the driving of the LED array according to the magnitude of the input voltage.

In the example of FIG. 11, when the input voltage divided by the resistors R1, R2, R3, and R4 is small, the comparator composed of OP1, OP2, and OP3 is connected in parallel to the flicker elimination capacitor C1 by 'ON' of SW1, SW2, and SW3. Only LED array G1 lights up through current limiting circuit CLC0, and as the input voltage gradually increases, SW1 is 'off' so that LED arrays G1 connected in parallel to C1 and G2 connected in parallel to C2 light up through current limiting circuit CLC0. . Then, when SW2 is 'off', the LED arrays G1, G2, and G3 are turned on through the current limiting circuit CLC0, and in the maximum voltage range, all the LED arrays G1 to G4 are turned off through the current limiting circuit CLC0. Lights up. Subsequently, in the decreasing period of the input voltage, the switching elements SW1 to SW3 are 'on' in the reverse order of lighting, so the LED arrays are turned off in the reverse order of lighting.

Therefore, the high efficiency direct-connect type LED driving circuit having the flicker elimination function of the second embodiment of the present invention prevents the inrush current of the switching element and eliminates the flicker by being consumed in the LED array without bypassing the charge charged in the flicker eliminating capacitor. In addition, the input voltage can be tracked even when the capacity of the flicker elimination capacitor is set to a large value.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. And various modifications and variations are possible within the scope of the appended claims.

C1, C2, C3, C4: flicker elimination capacitor
G1, G2, G3, G4: LED Array
OP1, OP2, OP3: Comparator
SW1, SW2, SW3: Switching element
CLC0: current limiting circuit

Claims (8)

The LED array is driven by a full-wave rectified voltage through the bridge diode (BD), and the current provided from the + terminal of the bridge diode is bypassed by the flicker elimination capacitor and switching element connected in parallel thereto or the LED array is A high efficiency direct-connect LED drive circuit with flicker cancellation configured to provide a current of
One or more LED arrays are connected in series
Both ends of the flicker elimination capacitor are connected to the anode and cathode terminals of a single LED array to form a group of LEDs.
A rectifying diode is connected in the forward direction between the cathode of the single LED array and the anode of the adjacent LED array so that each of the plurality of LED arrays is connected in series.
A switching element is connected in parallel between the cathode terminal of the LED array and the cathode terminal of an adjacent LED array connected to the LED array through a rectifying diode;
The rectifier diode connected to the LED array, the flicker elimination capacitor connected in parallel thereto, and the cathode of the LED array has a current supplied from the + terminal of the bridge diode according to 'on' and 'off' operation of the switching element. High-efficiency, direct-attached LED drive circuit with flicker cancellation, configured to be passed or provided as current in the LED array
The method of claim 1, wherein the one or more LED arrays,
High efficiency direct-connect LED drive circuit with flicker removal function, characterized in that the LED array connected to the + terminal of the bridge diode for the first time and the flicker removal capacitor connected in parallel are provided without a switching element.
The LED array is driven by a full-wave rectified voltage through the bridge diode (BD), and the current provided from the + terminal of the bridge diode is bypassed by the flicker elimination capacitor and switching element connected in parallel thereto or the LED array is A high efficiency direct-connect LED drive circuit with flicker cancellation configured to provide a current of
A bridge diode for full-wave rectifying power provided from a commercial AC power supply to a direct-connected LED driving circuit;
One end of the plurality of LED arrays is connected in series to the + and − terminals of the bridge diode;
A current limit circuit is connected to the other end of the plurality of LED arrays to provide a constant current to the plurality of LED arrays;
Both ends of the flicker elimination capacitor are connected to the anode and cathode terminals of a single LED array to form a group of LEDs.
A rectifying diode is connected in the forward direction between the cathode of the single LED array and the anode of the adjacent LED array so that each of the plurality of LED arrays is connected in series.
A switching element is connected in parallel between the cathode terminal of the LED array and the cathode terminal of an adjacent LED array connected to the LED array through a rectifying diode;
The rectifier diode connected to the LED array, the flicker elimination capacitor connected in parallel thereto, and the cathode of the LED array has a current supplied from the + terminal of the bridge diode according to 'on' and 'off' operation of the switching element. Pass or provide current from the LED array,
The switching element is driven by a comparator,
The comparator compares the applied voltage of the cathode terminal of the LED array to be switched with the reference voltage source and turns on the switching element when the applied voltage of the LED array cathode terminal is smaller than the reference voltage.
If the applied voltage of the LED array cathode terminal is larger than the reference voltage, the high efficiency direct-connect type LED driving circuit with flicker elimination function that controls the driving of the LED array according to the magnitude of the input voltage by 'off' the switching element.
The method of claim 3, wherein the plurality of LED arrays,
High efficiency direct-connect LED drive circuit with flicker removal function, characterized in that the LED array connected to the + terminal of the bridge diode for the first time and the flicker removal capacitor connected in parallel are provided without a switching element.
The method of claim 3, wherein the switching element is driven by a comparator,
The comparator compares the applied voltage of the cathode terminal of the LED array to be switched with the reference voltage source and turns on the switching element when the applied voltage of the LED array cathode terminal is smaller than the reference voltage.
If the applied voltage of the LED array cathode terminal is greater than the reference voltage, by 'off' the switching element,
Each LED array connected in parallel to the flicker removal capacitor is connected through a current limiting circuit.
High efficiency direct-connect LED drive circuit with flicker elimination, which controls the driving of the LED array according to the magnitude of the input voltage
The LED array is driven by a full-wave rectified voltage through the bridge diode (BD), and the current provided from the + terminal of the bridge diode is bypassed by the flicker elimination capacitor and switching element connected in parallel thereto or the LED array is A high efficiency direct-connect LED drive circuit with flicker cancellation configured to provide a current of
The power provided from the commercial AC power supply is full-wave rectified through the bridge diode and provided to the direct-connected LED driving circuit via the rectifying diode D0,
One end of the plurality of LED arrays is connected in series to the + and − terminals of the bridge diode;
A current limit circuit is connected to the other end of the plurality of LED arrays to provide a constant current to the plurality of LED arrays;
Both ends of the flicker elimination capacitor are connected to the anode and cathode terminals of a single LED array to form a group of LEDs.
A rectifying diode is connected in the forward direction between the cathode of the single LED array and the anode of the adjacent LED array so that each of the plurality of LED arrays is connected in series.
A switching element is connected in parallel between the cathode terminal of the LED array and the cathode terminal of an adjacent LED array connected to the LED array through a rectifying diode;
The rectifier diode connected to the LED array, the flicker elimination capacitor connected in parallel thereto, and the cathode of the LED array has a current supplied from the + terminal of the bridge diode according to 'on' and 'off' operation of the switching element. High-efficiency, direct-attached LED drive circuit with flicker cancellation, configured to be passed or provided as current in the LED array
7. The LED array of claim 6, wherein
High efficiency direct-connect type LED drive circuit with flicker removal function, characterized in that the LED array first connected via the rectifying diode D0 from the + terminal of the bridge diode and the flicker removal capacitor connected in parallel are provided without a switching element.
The switching device of claim 6,
Each driven by a comparator,
The comparator divides the voltage provided by the diode bridge for each switching voltage and compares it with a reference voltage source.
By turning on the switching element when the divided voltage divided by the reference voltage is smaller, and by turning off the switching element when the divided voltage divided by the reference voltage is larger,
Each LED array connected in parallel to the flicker removal capacitor is connected through a current limiting circuit.
Each LED array connected in parallel to the flicker removal capacitor is connected through a current limiting circuit.
High efficiency direct-connect LED drive circuit with flicker elimination, which controls the driving of the LED array according to the magnitude of the input voltage

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