KR20150000976A - AC Direct LED Driving Circuit for Improving Flicker - Google Patents

Abstract

The present invention relates to an LED driving circuit capable of reducing a crest factor and solving a flicker problem to satisfy not only a harmonics regulation and a power factor regulation but also a percent flicker regulation. Wherein, a light emitting diode (LED) module is directly driven with the alternating current (AC) power of a sinusoidal current.

Description

[0001] The present invention relates to an AC direct drive circuit for an LED,

The present invention relates to an LED driving circuit, and more particularly to an LED driving circuit in which an LED (Light Emitting Diode) module is directly driven by an AC (alternating current) power source of a sinusoidal current, which is suitable for harmonic regulation and power factor regulation, flicker, and to reduce the crest factor of the flicker problem.

In general, a conventional AC direct LED driving circuit applies an AC power supply voltage to two input terminals of a bridge diode and controls a current rectified by a bridge diode to drive the LEDs provided in the LED module to emit light. Korean Patent Application No. 10-2012-0120901, 10-2010-0104362 and the like can be referred to as related arts.

However, if the AC input voltage is low, there is a period in which the AC input current and the current flowing through the LED module become 0 (zero), which causes the flicker and the on / off state of the LED module I have not been able to resolve the blinking of the lighting. In order to solve this problem, there is an attempt to apply a valley fill circuit to the LED module so that current always flows. However, in a capacitor used in a valley fill circuit, an LED module The current flowing to the current source is not controlled and induces an overcurrent, which causes another problem of increasing the crest factor.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a direct current drive circuit for an LED module with an AC power source having a sinusoidal current suitable for harmonic regulation and power factor regulation, It uses a minimum of capacitors to drive the LED module with the energy charged in the capacitor when the input voltage is low, thereby providing an LED driving circuit that can improve the flicker problem by allowing current to flow through the LED module have.

Also, it is an object of the present invention to provide an LED driving circuit capable of controlling not only the current of the LED module but also the AC input current by controlling the charging / discharging current of the capacitor, thereby lowering the crest factor.

According to another aspect of the present invention, there is provided an LED driving circuit including: a plurality of LEDs (Light Emitting Diodes) connected in series to receive a power supply; Each of the three-terminal switches connected to the respective negative terminals of the plurality of LEDs, the main current switch having one terminal connected to the end of the last LED and the auxiliary switch having one terminal connected to the opposite terminal of each of the remaining LEDs except for the last LED, A light emission controller for controlling the light emission of the plurality of LEDs by controlling a current flowing through the plurality of LEDs in accordance with the rise and fall of a voltage of the power supply using a current switch; And an auxiliary current switch connected to each contact of the two LEDs of the plurality of LEDs supplies energy to the capacitor over a first magnitude of the voltage of the power source rising between a first contact and a ground connected to the LED The energy charged in the capacitor is supplied through a terminal receiving the power of the plurality of LEDs at a voltage equal to or lower than a second magnitude of the voltage of the power source which is charged and then dropped, And a flicker control unit for discharging the corresponding LEDs through a corresponding auxiliary current switch connected to the first contact.

Wherein the flicker control unit is configured to continuously flow a current to any one or more of the plurality of LEDs so that a current flowing through the plurality of LEDs becomes zero in response to fluctuations of a voltage of the power source, .

The flicker control unit supplies the charged energy to at least one of the remaining LEDs within the charged energy in a previous cycle of the voltage of the power source and uses the energy to be recharged to the capacitor in the next cycle, A current larger than the input current through the power source is not supplied through the capacitor, thereby lowering the crest factor.

The light emission control unit may be configured such that the other terminal of the auxiliary current switch and one terminal of the circuit for turning off the auxiliary current switch are both connected to the common contact, The auxiliary current switches and the main current switches are sequentially turned on one by one according to the rising and falling of the voltage of the power source so as to sequentially turn on the plurality of LEDs So that current flows.

The flicker control unit includes a first diode having one terminal connected to the first contact, a capacitor having one terminal connected to the other terminal of the first diode, a control circuit connected to another terminal of the capacitor, The control circuit controls the constant current to flow to the capacitor at the first magnitude or higher when the voltage of the power source rises to charge the capacitor using the second diode connected to the capacitor.

Wherein the charge current flowing through the capacitor by the control circuit between the first magnitude and the second magnitude of the voltage of the power supply is stopped and the flicker control unit A third diode connected between the terminals of the plurality of LEDs and a fourth diode connected between the second terminal and a corresponding terminal connected to the control circuit, Thereby discharging the capacitor.

When the position of the first contact is a k-th (k is a natural number smaller than n) and k + 1-th connection point among n LEDs of natural number n connected in series to constitute the plurality of LEDs, the charge from the time greater than the voltage (V _C1) and the total forward voltage of the plurality of the _{LED (n * V F) k} / n the (k * V _F) to a voltage _{(k * V F * + V} C1) plus the And the discharging is performed from when the power supply voltage becomes smaller than V _C1 at the time of falling after the power supply voltage is increased to the maximum size.

According to another aspect of the present invention, there is provided an LED driving circuit including: a plurality of LEDs (Light Emitting Diodes) connected in series to receive a power supply; Each of the three-terminal switches connected to the respective negative terminals of the plurality of LEDs, the main current switch having one terminal connected to the end of the last LED and the auxiliary switch having one terminal connected to the opposite terminal of each of the remaining LEDs except for the last LED, A light emission controller for controlling the light emission of the plurality of LEDs by controlling a current flowing through the plurality of LEDs in accordance with the rise and fall of a voltage of the power supply using a current switch; And charging the capacitor with a voltage equal to or greater than a first magnitude of the voltage of the power source rising according to a current control of a control circuit connected to a terminal of the light emission control unit between a terminal receiving the power source of the plurality of LEDs and a ground Wherein the energy stored in the capacitor is supplied to the plurality of LEDs through a terminal receiving the power of the plurality of LEDs to discharge the energy stored in the capacitor at a voltage lower than a second voltage of the power supply, And a flicker control unit for always removing the flicker by causing the current to flow without a section where the current flowing through the plurality of LEDs becomes zero.

The flicker control unit supplies the charged energy to the plurality of LEDs within the charged energy in a previous period of the voltage of the power source and recharges the capacitor in the next period to use the input current A larger current can not be supplied through the capacitor to lower the crest factor.

The flicker control unit includes a first diode, a second diode, and a third diode connected in series in a reverse direction between a terminal receiving the power source and the ground; A first capacitor coupled between a contact of the first diode and the second diode and another terminal of the control circuit; And a second capacitor connected between the second diode and the third diode.

Wherein the control circuit controls the first capacitor, the second diode, and the second capacitor so that a constant current flows through the first capacitor and the second capacitor when the voltage of the power source rises, Wherein the energy stored in the first capacitor through the connection between the first capacitor and the first diode is supplied to the terminal receiving the power when the voltage of the power source is lower than the second size, And discharge the energy charged in the second capacitor to the terminal receiving the power through the connection between the second capacitor and the third diode.

The present invention may be applied to drive an LED module having the plurality of LEDs formed of AC LED elements, in addition to the LED modules having the plurality of LEDs composed of DC LED elements.

According to the LED driving circuit of the present invention, when the input voltage is low using only the minimum capacitor, the LED module is driven by the energy charged in the capacitor, so that the current flows to the LED module in all the sections to control the percentage flicker The flicker problem can be improved so as to be suitable for the flicker. In this case, by controlling the charging / discharging current of the capacitor, not only the current of the LED module but also the AC input current can be controlled, thereby preventing the flicker (a problem in the application of the existing valley fill circuit) flicker) problems.

1 is a diagram for explaining an LED driving circuit according to an embodiment of the present invention.
2 is a waveform of voltage or current of each part according to time for explaining the operation of the LED driving circuit of FIG.
FIG. 3 is a photograph illustrating a comparison between the driving method according to the LED driving circuit according to the embodiment of the present invention and the flicker degree in the conventional LED driving method.
FIG. 4 shows an embodiment in which the number of LEDs of the LED module of FIG. 1 is four and the corresponding auxiliary current switch is expanded accordingly.
5 is a diagram for explaining an LED driving circuit according to another embodiment of the present invention.
6 is a waveform of voltage and current of each part for explaining flicker and crest factor improvement according to the operation of the LED driving circuit of Fig.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout.

1 is a diagram for explaining an LED driving circuit according to an embodiment of the present invention.

Referring to FIG. 1, an LED driving circuit according to an embodiment of the present invention includes an LED driving circuit 110 for driving an LED module 110 having two or more LEDs (Light Emitting Diodes) D ₁ and D ₂ connected in series, A rectifying unit 10, a light emission control unit 20, and a flicker control unit 30. 4 illustrates four LEDs, D ₁ , D ₂ , D ₃ , and D ₄ in the LED module 110 and thus may include two or more LEDs connected in series to the LED module 110, The light emission control section 20 is added with a light emission control circuit connected to each negative terminal of the added LEDs. Accordingly, the operation of the circuit will be described with reference to FIG. 1, and a person skilled in the art will be able to operate on the similar operation principle even if the number of LEDs included in the LED module 110 is four or the number of other LEDs is larger as shown in FIG. Can be easily understood. Here, each of the LEDs connected in series to the LED module 110 such as D ₁ , D ₂ , D ₃ , and D ₄ may be a single LED or a plurality of LED groups connected in series.

The rectifying part 10 (for example, a bridge diode) receives AC power Vac and supplies DC power, that is, rectified to a positive voltage, to the LED module 110. In the bridge diode, two sets of two diodes connected in series are connected in parallel, the series connection connection points are the input terminals of the AC power supply Vac, and the parallel connection connection points are the output terminals.

First, in operation of the light emission control unit 20, each of the three-terminal switches Q ₁ and Q ₂ connected to the respective negative terminals of the series-connected LEDs D ₁ and D ₂ of the LED module 110 (I _Q1 , i _Q2 ) flowing from each negative terminal connection point of the LEDs to the ground terminal to control the rising and falling of the power source rectified in the rectification section 10, more than 110), a positive terminal side constituting the LED of the LED (D ₁₎ (in Fig. _{4 D 1, D 2, D} 3) and the terminal-side end LED (D ₂₎ of the sound (in Fig. 4 D ₄₎ the And successively turns off in the reverse order. Here, the three-terminal switches Q ₁ and Q ₂ may be a metal-oxide-semiconductor field-effect transistor (MOSFET), a bipolar transistor, or the like. Further, the three-terminal switch (Q _1, Q ₂₎ of the gate of Q ₁ of the circuit for controlling the off (off) there is a shunt regulator (u1) connected to the other three-terminal switch Q _2, (in Fig. 4 Q _2, Q ₃ , and Q ₄ ) are connected to the gates of the switches q ₂ , q ₃ , and q ₄ , such as MOSFETs, bipolar transistors, and the like.

The auxiliary current switch Q ₂ (D ₁ , D ₂ , and D ₃ in FIG. 4) connected to the cathode side is connected to one or more LEDs D ₁ (D ₁ , D ₂ , and D ₃ in FIG. 4) sequentially turned on in response to the rising of the power rectified by the rectifying unit 10. ) (including the _{Q 4, Q 3, Q 2} ) and the final LED (D ₂₎ (the main current switches (Q ₁₎ for connected to the D ₄₎ in Fig. 4-4. Each auxiliary current switch (Q ₂₎ (in Fig. _{4 Q 4, Q 3, Q} 2) for the LED with the other side of the terminal and the switch for a second current (Q ₂₎ (Fig. 4 on the side connected to the Q _4, Q _3, circuit that turns off the Q ₂₎ (switch Q _4, Q _3, and a terminal connected to the common contact (COM) of the circuit coupled to the gate terminal of Q _2, respectively), when the switch (Q ₁₎ for the main current turned on , the common contact (in Fig. _{4 Q 4, Q 3, Q} 2) the secondary current switch (Q ₂₎ for through (COM) resistors coupled to respective gate terminals of the (R _B, R _B1, R _B2, R _{gs1 , R s1, R sen1, R} sen2 etc.) and the like, the current flows in the circuit under the control such that _{Q 4, Q 3, Q 2} ) is off at the switch for a second current (Q ₂₎ (Fig. Switch for the auxiliary current (Q ₂₎ (in Fig. _{4 Q 4, Q 3, Q} 2) circuit coupled to the respective gate terminals of a switch (q _2, q _3, q _4, and so on) in addition to the LED modules 110, of having the first LED anode side and a ground (GND) the resistors (R _B, R _B1, R _B2, R _gs1, R _s1, R _sen1, R _sen2, etc.) between the zener diode (ZD _B), the shunt regulator (u1).

Flicker control section 30 is either one of the two connection points between one LED of the LED module 110 (for example, the last LED (D ₂₎ on the anode side, Fig. 4, the anode side of the D _4), the forward diode (D _f1 is connected to the A reverse diode D _f2 connected to the anode side of the first LED D ₁ of the LED module 110, a forward diode D _f3 connected to the common contact COM as described above, And a reverse diode D _f4 connected between one terminal (e.g., source) of the control switch Q ₅ . In addition, between the other terminal of the D _f1 and D _f2 opposite connection contacts of the flickering control switch (Q ₅₎ (for example, drain) there is a capacitor (C ₁₎ connected to the gate terminal of the flicker control switch (Q ₅₎ that circuit, that is, resistance R _B5, MOSFET, switches, such as bipolar transistors q _5, the resistors connected to the gate of switch _{q 5 (R 5, R gs5} ) and the like are connected to the common contact (COM) as above that control And has a similar connection relationship to the circuit connected to the respective gate terminals of the auxiliary current switch Q ₂ (Q ₄ , Q ₃ , Q ₂ in FIG. 4).

The LED driving circuit of the present invention includes the flicker control unit 30 and uses only the minimum capacitor C ₁ to turn on the LED module 110 with the energy charged in the capacitor C ₁ when the input voltage is low, The flicker problem is improved so that the current flows to the LED module 110 in all periods to be suitable for the percent flicker regulation and the LED module 110 is controlled by controlling the charging / discharging current of the capacitor C ₁ . Not only the current of the AC power source 110 but also the input current I _ac of the AC power source V _ac can be controlled to improve the flicker problem without increasing the crest factor.

2 is a waveform of voltage or current of each part according to time for explaining the operation of the LED driving circuit of FIG.

2, for example, in the LED module 110 composed of n LEDs (n is a natural number) in FIG. 1, the input voltage Vac starts rising from positive at t ₀ as shown in FIG. and, voltage increases to the forward voltage of one-half (1/2 * n * V F) of the larger moment (t _1), the input current (I _ac) is a rectification part (10) than (V _F is the forward voltage LED) diode (BD ₁₎ to pass through, and the LED module 110 of one half (for example, D ₁₎ prepared already received supply voltage to pass through the resistor R _B, a Zener diode Z _DB, R _B2 (R _B2 in FIG. 4 ) Through MOSFET Q ₂ (Q 4 in FIG. ₄ ) through D ₁ radiation). At this time, the current flowing through the MOSFET Q ₂ is converted to a voltage through the sensing resistors R _sen2 , R _sen1 (R _{sen2 is} removable), and this voltage drives the gate of the switch q ₂ through R _off2 . Of course, this time the voltage across the gate of q ₂ are determined by the distribution voltage of the R _off2 and R _gs2 resistance when the voltage is driven to q ₂ in the active region, the auxiliary current i _Q2 flowing through the MOSFET Q ₂ is (input current, LED D _One The current is also controlled constantly as in the period from t ₁ to t _{2 in} FIG.

Further, in Fig. 2 t ₂ ~ t ₅ When the input voltage Vac is positive and the voltage further increases to become larger than the total forward voltage n * V _F (t ₂ ) for the n LED modules 110, the input current I _ac Passes through the diode BD ₁ of the rectifying section 10 and passes through the entire LED module 110 (D ₁ , D ₂ (D ₁ , D ₂ , D ₃ , D _{4 in} FIG. ₄ ) the supply received can flow through the MOSFET Q ₁ prepared by the _{R B, ZD B, R B1} (D 1, D 2 radiation). At this time, the instant (t ₂ ) at which the input voltage (Vac) becomes greater than the total forward voltage (n * V _F ), the current (i _Q1 ) flowing through the MOSFET Q ₁ starts to flow immediately and flows through the diode (D _f1 ) C1) for charging, and the input voltage (Vac) at this moment is larger than the voltage obtained by adding a capacitor voltage (V _C1) and the forward voltage of _{1/2 (0.5 * n * V F} ) of the LED module (110) (t _3), The current i _Q5 flowing through the MOSFET Q ₅ and the diode D _f3 begins to flow. Therefore, the current flows only through the MOSFET Q ₁ and the input voltage Vac becomes larger (0.5 * n * V _F *) as the input voltage Vac reaches the total forward voltage n * V _F of the LED module 110. Therefore, + V _C1 ), the current flows through MOSFET Q ₁ , Q ₅ . Current flowing through the MOSFET Q ₅ is gradually charged to the capacitor C ₁ increases the capacitor voltage (V _C1), wherein the current is, since the control with the constant current capacitor voltage (V _C1) also increases linearly (t ₃ ~ t ₄ ).

Above, also in the circuit 1 by a current flowing through the capacitor C ₁ when greater than the input voltage (Vac) is _{(0.5 * n * V F *} + V C1) ( where, n = 2) charging the capacitor C ₁ for a description was, Figure 4 shows the input voltage (Vac) is (3/4 * n * V F * + V C1) ( where, n = 4) current and the capacitor C ₁ flows through the capacitor C ₁ when greater than the Charging. When the diode D _f1 is connected to the kth (k is a natural number smaller than n) and the (k + 1) th connection point among the n series-connected n LEDs constituting the plurality of LEDs of the LED module 110 (K / n * nV _F ) of the capacitor voltage (V _C1 ) and k / n of the total forward voltage (n * V _F ) of the plurality of LEDs when the input voltage (Vac) V _F * + V _C1 ).

In this way is the driving force to the low voltage (V _C1), the input voltage (Vac) is charged in the capacitor section drives the 1/2 (D ₁₎ of the LED module 110 to improve the flicker. This operation continues while the input voltage Vac increases to the maximum level (0.5 * n * V _F * + V _C1 ), and the input voltage Vac begins to decrease so that the input voltage becomes 0.5 * n * V _F * + V _{C1 When the} voltage becomes smaller than the voltage (t ₄ ), the charging current flowing through the capacitor C ₁ stops and the current flows only through the MOSFET Q ₁ as in the early stage.

The current flowing through the MOSFETs Q ₁ and Q ₅ is converted to a voltage through the sense resistor (R _sense1 ) (which may include R _sense2 ), which through R _S1 and R ₅ is the reference sustain voltage of the regulator (u ₁ ) reference), and drive the gate of q ₅ . Of course, this time the voltage across the gate of the reference holding voltage (reference) and q ₅ of u ₁ is each R _S1 and R _gs1, R ₅ and R _gs5 is determined by the distribution voltage of the resistance voltage is active for u ₁ and q _5, respectively The currents flowing through the MOSFETs Q ₁ and Q ₅ can be constantly controlled as in the period from t ₂ to t _{5 in} FIG. 2 (see input current and LED current in FIG. 2). The MOSFET q ₂ operates in the saturation region due to the distributed voltage design of the R _off2 and R _gs2 resistors while the current flows through the MOSFET Q ₁ or Q ₅ , so that MOSFET Q ₂ is off and no current flows .

On the other hand, in Fig. 2, t ₅ In the later period, first, the input voltage (Vac) is reduced to be small moment than the total forward voltage (n * V _F) of the module is configured open-circuit n (t _5), the input current (I _ac) has a rectifier diode (BD ₁₎ and passed through a, LED module 110 may be a current flow through the entire MOSFET Q ₂ by the R _B, ZD _B, R _B2 prepared already received supply voltage to pass through only half of the (Q _1, the current does not flow Not). This operation lasts until the instant t ₆ when the input voltage is less than the maximum charged V _C1 . At this time, the flowing current is a voltage change to the voltage over the sensing resistor (R _sens1) (R _sens2 including possible) drives the gate of q ₂ through R _off2. Of course, the voltage at the gate of q ₂ is R _off2 and R _gs2 If the voltage is determined to be the distribution voltage of the resistor and q ₂ is driven in the active region, the auxiliary current i _Q2 flowing in the MOSFET Q ₂ can be controlled to be kept constant as in the period from t ₅ to t _{6 in} FIG.

At the instant t ₆ when the input voltage Vac decreases and becomes smaller than the maximum charged voltage V _C1 , the input current I _ac stops flowing and the energy charged in the capacitor C ₁ charge) is driving the LED with _{D 1, D 2, D 3} ) between the LED terminal that receives the power of (D ₁₎ (FIG. 4 LED module (110 in) and a diode (D _f1) is connected to LED between the contact . Since the energy stored in the capacitor C ₁ is used as a constant current, the capacitor voltage V _C1 also decreases linearly. At this time, the capacitor (C ₁₎ of the capacitance value until large enough to drive the one-half of the LED module 110 by increasing the full wave rectified input voltage back (t ₆ t ₈ ~) LED (D _1), the current So that the flicker problem can be solved.

2 of ₆ t ~ t Referring the flow of current for _8, a capacitor (C ₁₎ energy is a diode (D _f2) via the LED through a 1/2 (D ₁₎ of the module 110, a MOSFET switch for a second current Q ₂ and the diode (D _{f4 )} . The current flowing through MOSFET Q ₂ is converted to a voltage through the sense resistor (R _sense1 ), which drives q ₂ through R _off2 . Of course, this time the voltage across the gate of q ₂ is R _off2 and R _gs2 is determined by the distribution voltage of the resistance voltage when driving the q ₂ in the active region, the auxiliary current i _Q2 flowing through the MOSFET Q ₂ can be controlled constant . Accordingly, it is possible to minimize the number of parts added to the control of the capacitor (C ₁₎ the discharge current using the conventional auxiliary current controlling MOSFET Q ₂ and q _2.

As shown in FIG. 2, in the LED driving method according to an embodiment of the present invention, even when the input voltage (Vac) is small, the current flowing through the LED module 110 becomes zero The current can be continuously flowed without a section to improve the flicker problem as illustrated in FIG. 3, and the overcurrent as in the conventional valley fill circuit does not occur in the input current, thereby lowering the crest factor . In other words, the charged energy is supplied to at least one of the LEDs (e.g., D ₁ ) within the energy charged in the capacitor C ₁ in the previous cycle of the AC power source voltage Vac, uses to energize the (C _1), thereby a current larger than the input current through the power to reduce the crest factor not to be supplied through the capacitor (C _1).

5 is a diagram for explaining an LED driving circuit according to another embodiment of the present invention.

5, the LED driving circuit according to another embodiment of the present invention is similar to that of FIG. 1 except that the LED module 110, the rectifying part 10, and the light emitting control part 20 are similar in configuration to the flicker control part 30 have different configurations from those of Fig.

D ₁ , D ₂ are exemplified as the LED module 110, but it is not limited thereto. Those skilled in the art will appreciate that the number of LEDs included in the LED module 110 is four (D ₁ , D ₂ , D ₃ , D ₄ ), it can be easily understood that the same operation principle of the flicker control unit 30 operates on the corresponding configuration of the light emission control unit 20 for driving a single LED or a plurality of LED groups.

5, the flicker control unit 30 includes a first diode D _f1 connected in series in the reverse direction and a second diode D _f2 connected in series between the terminal receiving the input voltage of the LED module 110 or the power source Vac and the ground GND, D _f2 and a third diode D _f3 and the contacts of the first diode D _f1 and the second diode D _f2 and the control circuits Q ₅ , Q ₅ , R _B5 , R ₅ , R _and a first capacitor C ₁ connected between the terminals of the second diode D _f2 and the third diode D _f3 connected between the terminals of the second diode D _f2 and the third diode D _f3 , And a second capacitor (C ₂ ).

The control circuit is one terminal of the (Q _5, q _5, R _B5, R _5, R _gs5) through the resistor R _B is connected with one character of the resistance R _B of the light emission control section) 20, a control circuit (Q _5, the charging current at the time of charging the first capacitor C ₁ and the second capacitor C ₂ can be made to flow constantly according to the current control of the transistors Q ₁ , Q ₅ , R _B5 , R ₅ and R _gs5 . That is, the flickering control switch (Q ₅₎ in Fig. 5 circuit coupled to the gate terminal of the (source terminal (R _5, connected to the contacts of the R _gs5)), that is, resistance R _B5, MOSFET, switches, such as bipolar transistors q ₅ and the resistors R ₅ and R _{gs 5} connected between the gate of the switch q ₅ and the ground are connected to the first capacitor C ₁ according to the control as described above according to the operation of the light emission control unit 20, , The charging current at the time of charging the second capacitor (C ₂ ) can be made to flow constantly.

For example, the flicker control unit 30 controls the flicker control unit 30 according to the control of the control circuit (Q ₅ , Q ₅ , R _B , R ₅ , R _{gs 5} ) (See 89 in FIG. 6) of the voltage of the power source Vac that charges and falls to the _first and second capacitors C ₁ and C ₂ in the first and second capacitors C ₁ and C 6 The current flowing through the LED module 110 due to the fluctuation of the voltage of the power source Vac is supplied to the LED module 110 through the front terminal receiving the power source Vac of the LED module 110, So that the flicker can be removed by allowing the current to flow at all times without a period of 0 (zero).

For example, more than the first size when the voltage rise of the power source (Vac) (see 59 in FIG. 6) in the control circuit (Q _5, q _5, R _B5, R _5, R _gs5), the first capacitor by (C _1), a second diode (D _f2), and a second capacitor (C ₂₎ a first capacitor (C ₁₎ and a second capacitor (C ₂₎ is controlled to a constant current (i _Q5) flowing through It can be charged.

When the voltage of the power source Vac is lowered, the first capacitor C ₁ and the first diode D _f1 are connected to each other through a corresponding relationship between the first capacitor C ₁ and the first diode D _f1 , The energy charged in the capacitor C ₁ is discharged to the terminal receiving the power supply Vac and the energy stored in the second capacitor C ₂ through the corresponding operation of the connection between the second capacitor C ₂ and the third diode D _f3 C ₂ can be discharged to the terminal receiving the power source Vac.

The flicker control unit 30 supplies the charged energy to the LEDs of the LED module 110 within the energy charged in the capacitors in the previous cycle of the voltage of the power source Vac, Since the capacitors are recharged and used, the current that is larger than the input current through the power source Vac is not supplied through the capacitors, so that the crest factor can be lowered. In addition, flicker can be removed by allowing the current to flow constantly without a period in which the current flowing through the plurality of LEDs of the LED module 110 becomes 0 (zero) due to the fluctuation of the voltage of the power source Vac. And the LEDs D ₁ , D ₂ , D ₃ and D ₄ of the LED module 110 are DC direct current LED devices. However, those skilled in the art can similarly apply it to drive an AC (Alternating Current) LED module through a slight design change to the control circuit for the LED module made of the DC LED elements described above. For example, the operation method of the control circuit described above can be applied to easily drive the LED module 110 formed of the AC LED elements directly to the AC power source Vac without using the rectifying part 10 as described above.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. This is possible. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined by the equivalents of the claims, as well as the claims.

The rectifying part (10)
The light-
The flicker control unit (30)
The LED module (110)

Claims (12)

A plurality of LEDs (Light Emitting Diodes) connected in series to receive power input;
Each of the three-terminal switches connected to the respective negative terminals of the plurality of LEDs, the main current switch having one terminal connected to the end of the last LED and the auxiliary switch having one terminal connected to the opposite terminal of each of the remaining LEDs except for the last LED, A light emission controller for controlling the light emission of the plurality of LEDs by controlling a current flowing through the plurality of LEDs in accordance with the rise and fall of a voltage of the power supply using a current switch; And
Any one of the auxiliary current switches connected to the respective contacts of the two LEDs of the plurality of LEDs is charged between the first contact connected to the LED and the ground and the capacitor at a voltage greater than a first magnitude of the voltage of the rising power source The energy stored in the capacitor is supplied through a terminal receiving the power of the plurality of LEDs at a voltage equal to or lower than a second magnitude of the voltage of the power source, A flicker control unit for discharging the LEDs through the corresponding auxiliary current switch connected to the first contact,
And an LED driving circuit for driving the LED driving circuit. The method according to claim 1,
Wherein the flicker control unit comprises:
Wherein a current is always supplied to any one or more of the plurality of LEDs to eliminate the flicker without a period in which a current flowing through the plurality of LEDs becomes 0 (zero) due to fluctuations of the voltage of the power source. Drive circuit. The method according to claim 1,
Wherein the flicker control unit comprises:
Supplying the charged energy to at least one of the remaining LEDs within the charged energy in a previous period of the voltage of the power source and recharging the capacitor in the next period to use the input current Wherein a larger current is not supplied through the capacitor to lower the crest factor. The method according to claim 1,
The light-
The other terminal of the auxiliary current switch and the terminal of the circuit for turning off the auxiliary current switch are all connected to the common contact and the resistor is connected between the resistors through which the current flows when the main current switch is turned on, The auxiliary current switches and the main current switches are sequentially turned on one by one as the voltage of the power source rises and falls so that the current flows sequentially through the plurality of LEDs The LED driving circuit comprising: The method according to claim 1,
Wherein the flicker control unit comprises:
A first diode connected at one terminal to the first contact, a capacitor coupled to one terminal of the other terminal of the first forward diode, a control circuit coupled to another terminal of the capacitor, and a second terminal coupled to one terminal of the control circuit, Wherein the capacitor is charged by controlling the constant current to flow to the capacitor by the control circuit when the voltage of the power source is higher than the first magnitude by using the diode. 6. The method of claim 5,
The charge current flowing to the capacitor by the control circuit between the first magnitude and the second magnitude of the voltage of the power supply stops,
The flicker control unit may further include a third diode connected between the other terminal of the first diode and the terminal of the plurality of LEDs receiving the power supply and a second diode connected between the corresponding terminal connected to the control circuit and the ground, 4 < / RTI > diode is further used to discharge the capacitor below the second magnitude when the voltage of the power supply falls. The method according to claim 6,
When the position of the first contact is a kth (k is a natural number smaller than n) and a k + 1th connection point among n LEDs connected in cascade and constituting the plurality of LEDs,
The person at the time of rise of the supply voltage k / n of the capacitor voltage (V _C1) and the total forward voltage (n * V _F) of the plurality of LED (k * V _F) the voltage obtained by adding the (k * V _F * + V _C1 ), and the discharging is performed from the time when the power supply voltage becomes larger than the maximum magnitude and then the power supply voltage becomes lower than V _C1 at the time of falling. A plurality of LEDs (Light Emitting Diodes) connected in series to receive power input;
Each of the three-terminal switches connected to the respective negative terminals of the plurality of LEDs, the main current switch having one terminal connected to the end of the last LED and the auxiliary switch having one terminal connected to the opposite terminal of each of the remaining LEDs except for the last LED, A light emission controller for controlling the light emission of the plurality of LEDs by controlling a current flowing through the plurality of LEDs in accordance with the rise and fall of a voltage of the power supply using a current switch; And
According to the current control of the control circuit connected to the terminal of the light emission control unit, energy is charged to the capacitor at a voltage equal to or greater than a first magnitude of the voltage of the power supply rising between the terminal receiving the power supply of the plurality of LEDs and the ground, Wherein the energy stored in the capacitor is supplied to the plurality of LEDs through a terminal to which the power of the plurality of LEDs is supplied by discharging the energy stored in the capacitor at a voltage lower than a second magnitude of the voltage of the power source, A flicker control section for always removing the flicker by allowing the current to flow without a section where the current flowing through the LED is zero
And an LED driving circuit for driving the LED driving circuit. 9. The method of claim 8,
Wherein the flicker control unit comprises:
Wherein the controller is configured to supply the charged energy to the plurality of LEDs within the charged energy in a previous period of the voltage of the power source and to recharge the capacitor in the next period to use the current larger than the input current through the power source, And the capacitor is not supplied through the capacitor, thereby lowering the crest factor. 9. The method of claim 8,
Wherein the flicker control unit comprises:
A first diode, a second diode, and a third diode connected in series in a reverse direction between a terminal receiving the power supply and the ground;
A first capacitor coupled between a contact of the first diode and the second diode and another terminal of the control circuit; And
And a second capacitor connected at both ends thereof to a contact point between the second diode and the third diode,
And an LED driving circuit for driving the LED driving circuit. 9. The method of claim 8,
Wherein the first capacitor and the second capacitor are controlled by the control circuit so that a constant current flows through the first capacitor, the second diode, and the second capacitor when the voltage of the power source rises, Charging the second capacitor,
Discharging the energy charged in the first capacitor through a connection relationship between the first capacitor and the first diode to a terminal receiving the power source at a voltage lower than the second size when the voltage of the power source falls, And discharges energy charged in the second capacitor through a connection between the capacitor and the third diode to a terminal receiving the power. The method according to claim 1 or 8,
An LED module having the plurality of LEDs formed of DC LED elements, or an LED module having the plurality of LEDs formed of AC LED elements.

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