KR20150010176A - LED illumination device involving flicker reducing circuit - Google Patents

Abstract

An objective of the present invention is to include a flicker reducing circuit to reduce a flicker phenomenon induced by change in input voltage. For this, provided is an LED lighting device that includes a flicker reducing circuit, the device including a power supply unit supplying input power; a rectifier circuit unit which is supplied with the input power from the power supply unit to output rectified power supply; a charge storage circuit unit which is supplied with the rectified power supply from the rectifying circuit unit to store the electric charge in case of a high voltage and discharges the electric charge in case of a low voltage; an LED unit which has multiple LED channels connected in series and has a resistor unit connected to the last end of the LED channel; and a switch circuit unit that includes a current sensing resistor and multiple switches, wherein an n-th switch is connected to the rear end of an n-th LED channel to control the operation of the LED channel, and the sum of the current of the n-th switch flowing on the current sensing resistor and the current of the n+1-th switch controls the n-th switch.

Description

TECHNICAL FIELD [0001] The present invention relates to an LED illumination device including a flicker reducing circuit,

The present invention relates to an LED (Light Emitting Diode) lighting apparatus, which includes a circuit for automatically switching a switch for operating an LED according to an input voltage and reducing a flicker phenomenon to reduce a flicker phenomenon, The present invention relates to a lighting device for solving the problem of heat generation occurring in a switching IC which is generated when an input signal is inputted.

In recent years, LED diodes (hereinafter referred to as LEDs) have been widely used in lighting devices due to their low power, high efficiency and long service life.

To use the LED as a light source, a switching circuit that operates the LED according to the input voltage is needed.

The conventional switching circuit includes a voltage sensing circuit or a period sensing circuit, and controls a switch corresponding to the LED by sensing a voltage level or a voltage input period according to an input voltage. However, since such a conventional switching circuit includes a voltage sensing circuit or a period sensing circuit, there arises a problem that the size of the entire circuit increases. Therefore, the area that can further include the LED is reduced.

In addition, the switching circuit is composed of FETs. Such FETs are susceptible to the invention because they are sensitive components. Here, when the input voltage is inputted at a rated voltage or more, there is a problem that a lot of heat is generated in the switching circuit. That is, when the input voltage is inputted at a rated voltage or higher, a high amperage current flows to the switching circuit, which causes a problem that a large amount of heat is generated in the switching circuit.

U.S. Patent No. 6,989,807 discloses a feature in which LEDs can be driven at a voltage varying in real time by adjusting a plurality of switches connected in parallel to a plurality of LED groups serially connected at an AC input voltage varying in voltage in real time , US Patent No. 6,989,807 also includes a voltage sensing circuit for sensing the input voltage. When the rated voltage is 100% or more, an excessive amount of heat is generated in the switching circuit, The efficiency is lowered, and the possibility of malfunction of the circuit due to the high heat generated in the switching circuit is increased.

In addition, in the conventional LED illumination device, a flicker phenomenon occurs depending on the magnitude of the input voltage.

In order to solve the conventional problems of the present invention, it is an object to reduce a flicker phenomenon due to a change in input voltage by including a circuit for reducing the flicker phenomenon.

It is a further object of the present invention to provide a switching IC circuit comprising a FET, which is constructed by connecting a resistor for heat dissipation to an LED unit to which a plurality of LEDs are connected, To reduce the heat generated by the switching IC circuit.

It is still another object of the present invention to provide a sensing resistor to automatically switch according to a voltage generated in a sensing resistor.

It is still another object of the present invention to provide a switch circuit unit without configuring a voltage sensing circuit or a periodic sensing circuit for sensing an input voltage so that an LED can be additionally formed in a limited area.

Other objects of the present invention will become readily apparent from the following description of the embodiments.

According to an aspect of the present invention, there is provided a rectifier circuit comprising: a rectifier circuit part for receiving input power from the power source part and outputting rectified rectified power; A charge storage circuit part for discharging the stored charge when the voltage is low and an LED part having a plurality of LED channels connected in series and a resistor part connected to a last end of the LED channel, And the nth switch is connected to the rear end of the nth LED channel to control the operation of the LED channel, and the sum of the current of the nth switch flowing in the current sensing resistor and the current of the n + 1th switch A switch circuit portion in which an nth switch is controlled by a switch circuit; And a circuit for reducing the flicker phenomenon including the flicker phenomenon.

Here, a resistor may be connected to the last LED channel, and the switch circuit may include a switch connected to the resistor, so that the resistor reduces the heat generated by the switch circuit.

Here, the LED channel may include one or more LEDs.

Here, the n-th LED channel may have a different forward voltage Vf to reduce the power consumption of the n-th switch.

Here, the saturation current of the (n + 1) th switch is set higher than the saturation current of the nth switch.

Here, the voltage of the variable resistor is changed by the sum of the currents flowing through the nth and (n + 1) th switches, and the input voltage is greater than or equal to the forward voltage (Vf) of the (n + When the saturation current flows through the (n + 1) th switch, the nth switch is turned off.

Here, the charge storage circuit portion includes a first capacitor, a second capacitor, a first diode, a second diode, and a third diode, and the second diode is connected in a forward direction between the first capacitor and the second capacitor One end of the first capacitor is connected to a power supply voltage node of the rectifier circuit and the other end of the second capacitor is connected to the ground, and the first diode is connected to a node between the first capacitor and the second diode And the third diode is connected between the node and a node between the second capacitor and the second diode, and the voltage output from the rectifying circuit part is connected to the charge storage circuit part And discharges the stored charge to supply the voltage to the LED unit Can.

The present invention has an effect of preventing the excessive heat generation of the switch circuit portion and normally maintaining the operation of the switch circuit portion constituted by the IC even when the rated voltage or higher is inputted by constituting the resistor stage which distributes the heat of the switch circuit portion.

Further, there is an effect that the forward voltage of the LED channel is redistributed to reduce the power consumed in the switch circuit portion, thereby increasing the efficiency.

Further, there is an effect that the switch for driving the LED can be automatically controlled according to the input voltage.

In addition, a circuit for reducing the flicker phenomenon is included to reduce the flicker phenomenon according to the input voltage.

1 is a diagram illustrating a structure of an LED illumination device including a circuit for reducing a flicker phenomenon according to an embodiment of the present invention.
2 is a view for explaining the structure and function of the charge storage circuit portion according to an embodiment of the present invention.
3 is a diagram illustrating the magnitude of voltage supplied to the LED operation unit according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is capable of various modifications and various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. 1 < / RTI > and 2 or these terms are used only for the purpose of distinguishing one element from another. Also, the singular expressions may include plural expressions unless the context clearly dictates otherwise.

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

1 is a diagram illustrating a structure of an LED illumination device including a circuit for reducing a flicker phenomenon according to an embodiment of the present invention.

An LED illumination apparatus including a circuit for reducing the flicker phenomenon of the present invention includes a power supply section 10, a rectification circuit section 20, a charge storage circuit section 100, and an LED operation section 200.

The power supply unit 10 supplies input power. Since the power source unit 10 uses an AC power source, the magnitude of the input voltage periodically changes with time.

The rectifying circuit section 20 receives the AC input power from the power supply section 10 and outputs rectified rectified power.

The charge storage circuit unit 100 stores the charge when the voltage input from the rectifying circuit unit 20 is a high voltage and discharges the stored charge to the LED operation unit 200 when the voltage is low.

The detailed structure and function of the charge storage circuit portion 100 will be described later with reference to FIG.

The LED operation section 200 includes an LED section 30, a switch circuit section 40, and a current sensing resistor 50.

The LED unit 30 includes a plurality of LED channels connected in series and a resistor unit 35 is connected to a lower end of the last LED channel 34.

The switch circuit unit 40 includes n + 1 switches for operating the LED channels according to the input power source. Here, the n switches control the operation of the LED channel according to the input power, and the (n + 1) th switch operates the resistor 35.

Hereinafter, for convenience of explanation, it is assumed that n = 4.

Referring to FIG. 1, the second LED channel 32 and the first switch 41 are connected to the next end of the first LED channel 31. The third LED channel 33 and the second switch 42 are connected to the next stage of the second LED channel 32. [ And the fourth LED channel 34 and the third switch 43 are connected to the next stage of the third LED channel 33. [ The resistor unit 35 and the fifth switch 44 are connected to the next stage of the fourth LED channel 34. [ The fifth switch 45 is connected to the next stage of the resistor 35. [

Here, each of the switches is composed of a FET (Field Effect Transistor). In particular, it is composed of an NMOS FET.

The current sensing resistor 50 is connected to each switch 41, 42, 43, 44, 45 included in the switch circuit portion 40. Therefore, when a current flows through the switch, the current flowing through the current sensing resistor 50 becomes the sum of the currents flowing through the switch.

The current sensing resistor 50 may be constituted by a variable resistor.

In the present invention, the LED channel operates according to the magnitude of the input power. The corresponding LED channel operates according to the magnitude of the rectified power input to the LED unit 30. [

The operation of the switch unit 40 of the present invention is as follows.

First, in the initial stage, all the switches 41, 42, 43, 44, and 45 are set to the on state.

The switch of the switch unit 40 is automatically controlled by the voltage value applied to the current sensing resistor 50 according to the magnitude of the rectified voltage input to the LED unit 30 to operate the LED channel.

The current sensing resistor 50 in the present invention is set to, for example, 10 ohms.

Table 1 below shows the saturation current value according to the switch (FET) and the voltage across the current sensing resistor 50 when the saturation current flows through the switch.

Here, Id denotes saturation current of the corresponding switch. Means a saturated voltage when a switch operates and current flows. Vrs denotes a voltage applied to the current sensing resistor 50.

Id (mA) Vrs 1 FET 20 0.2 2 FET 40 0.4 3 FET 60 0.6 4 FET 80 0.8 5 FET 100 1.0

It is also assumed that the forward voltage Vf of each LED channel is 50V.

In this case, when the input voltage rises to reach about 50 V, the first LED channel 31 operates and the current I1 flows slowly through the first switch 41. When the input voltage exceeds 50 V, the saturation current of 20 mA flows in the first switch 41 and the voltage applied to the current sensing resistor 50 becomes 0.2V.

When the input voltage rises to reach 100 V, the second LED channel 32 operates and the current I2 flows slowly through the second switch 42. At this time, in the current sensing resistor 50, the current flows by the sum of the current flowing in the first switch 41 and the current I2 flowing in the second switch 42. Therefore, the voltage of the current sensing resistor 50 gradually increases. When the voltage applied to the current sensing resistor 50 rises, the voltage Vgs1 input to the gate of the first switch 41 becomes relatively low, so that the first switch 41 is switched from the on state to the off state. When the input voltage gradually increases and the current I2 flowing in the second switch 42 gradually increases, the voltage applied to the current sensing resistor 50 gradually rises and the voltage value of Vgs1 is relatively low So that the first switch 41 is turned off.

When the input voltage becomes 100 V or more, the second switch 42 has a saturation current of 40 mA and the first switch 41 is completely turned off.

When the input voltage rises to reach about 150 V, the third LED channel 33 operates and the current I3 gradually flows through the third switch 43. At this time, in the current sensing resistor 50, a current flows as much as the sum of the current flowing in the second switch 42 and the current I3 flowing in the third switch 43. Therefore, the voltage applied to the current sensing resistor 50 is gradually increased. When the voltage applied to the current sensing resistor 50 rises, the voltage Vgs2 input to the gate of the second switch 42 becomes relatively low, so that the second switch 42 is switched from the on state to the off state. And when the voltage value of the current sensing resistor 50 gradually increases and the voltage value of Vgs2 becomes relatively low, the second switch 42 is turned off.

When the input voltage exceeds 150V, the third switch 43 is supplied with a saturation current of 60 mA and the second switch 42 is completely turned off.

As described above, according to the input voltage, when the switch starts to flow current to the (n + 1) th switch sequentially, the nth switch is turned off.

When the input voltage rises to reach 200 V, the fourth LED channel 34 operates and the currents I3 and I4 flow slowly through the third switch 43 and the fourth switch 44. [ At this time, the current flows through the current sensing resistor 50 by the sum of the current flowing through the third switch 43 and the current flowing through the fourth switch 44 and the fifth switch 45. Likewise, when the input voltage becomes 200 V or more, the fourth switch 44 is supplied with a saturation current of 80 mA and the third switch 43 is completely turned off.

However, when a voltage higher than the rated voltage is input (for example, about 250 V), the fourth switch 44 is turned off and the fifth switch 45 is operated only for the same reason.

Assuming that an LED channel is connected instead of a resistor at the position of the resistor 35 as in the conventional case, when an input voltage higher than the rated voltage is inputted, an excessive current flows to the switch 45, do. That is, excessive current is generated in the switch for operating the last LED channel. Therefore, excessive heat generated in this way has a considerably bad influence on the switch circuit portion 40 composed of the IC parts, resulting in a failure of the component and a reduction in efficiency due to the generated heat.

Therefore, when the resistor 35 is connected to the last end of the LED 30 as in the present invention and the voltage is divided by the resistor 35, The heat generated by the fifth switch 45 is prevented from being excessively generated. Thus, in the present invention, even when the input voltage is inputted at a rated voltage or higher, excessive heat generated in the switch circuit portion 40 is partially distributed in the resistor portion 35 and is generated, thereby causing the switch circuit portion 40, And the stability of the switch circuit portion 40 can be maintained.

In addition, the present invention can have the following characteristics in terms of power consumption.

When the input voltage rises from the first switch to the fourth switch, the voltage is canceled by the forward voltage in the n-th LED channel and the n-th switch is operated with the remaining voltage. When the voltage higher than the forward voltage is inputted, (N + 1) switches are operated. Therefore, the power consumed by each switch increases, but the overall power consumption is within a predetermined system specification range. However, when the fifth switch 45, which is the last switch, receives a rated voltage or more, excessive current flows and the consumed power (heat) exceeds the specification range of the system. Therefore, when the rated voltage or more is inputted, the fifth switch 45 generates excessive heat.

In the present invention, even when a resistor unit 35 is provided and a rated voltage or more is inputted, the heat generated in the fifth switch 45 can be canceled by generating heat in the resistor unit 35.

Also, in the present invention, the forward voltage Vf of each LED channel is redistributed differently, so that power consumed by each switch can be made almost equal. That is, the forward voltage Vf of the (n + 1) -th LED channel is made higher than the forward voltage Vf of the nth LED channel, and the powers consumed by the nth and (n + 1) . By redistributing the forward voltage Vf of the LED channel in this way, even when the input voltage changes, the heat generated in the switch circuit 40 can be made equal.

Here, the forward voltage Vf can be freely changed and arranged for each LED channel, but the sum of the forward voltages Vf is set to the maximum value of the input voltage.

2 is a view for explaining the structure and function of the charge storage circuit portion according to an embodiment of the present invention.

The charge storage circuit unit 100 includes a first capacitor 101, a second capacitor 104, a first diode 105, a second diode 103, and a third diode 106.

The circuit structure of the charge storage circuit part 100 is such that a second diode 103 is connected in a forward direction between the first capacitor 101 and the second capacitor 104 and one side of the first capacitor 101 is connected to the rectification circuit part 20 And a first diode 105 is connected between a node between the first capacitor 101 and the second diode 103 and a ground between the node connected to the first diode 101 and the second diode 103, And the third diode 106 is connected between the node to which the second capacitor 104 and the second diode 103 are connected and the LED unit 30. Here, the resistor 102 may be further connected between the node between the first capacitor 101 and the first diode 105 and the second diode 103.

The charge storage circuit part 100 receives a voltage from the rectifying circuit part 20 and stores the charge. When the voltage output from the rectifying circuit unit 20 is lower than the voltage stored in the charge storage circuit unit 100, the stored charge is discharged to supply power to the LED operation unit 200.

The charge storage circuit unit 100 discharges the charge stored in the rectifier circuit unit 20 when the voltage output from the rectifier circuit unit 20 is low and supplies power to the LED unit 30 of the LED operation unit 200, It is possible to supply a voltage to the LED subchannel which can not operate when a low voltage is output from the subchannel. Accordingly, even when a low input voltage is inputted from the power supply unit 10, the flicker phenomenon can be reduced by operating an LED channel that can not operate.

In FIG. 2, arrows indicate paths in which charge is stored in the charge storage circuit portion 100 when the voltage output from the rectifying circuit portion 20 is a high voltage. When the voltage output from the rectifying circuit section 20 is a high voltage, the electric charge storage circuit section 100 causes a current to flow through the first capacitor 101, the second diode 103, and the second capacitor 104, Electric charges are stored in the first capacitor 101 and the second capacitor 104. When the voltage output from the rectifying circuit section 20 is a low voltage (that is, when the voltage is lower than the voltage stored in the charge storage circuit section 100), the charge stored in the first capacitor 101 and the second capacitor 104 And supplies the voltage to the LED unit 30. [

3 is a diagram illustrating the magnitude of voltage supplied to the LED operation unit according to an embodiment of the present invention.

In the present invention, the magnitude of the voltage input to the LED operation unit 200 changes as shown in FIG.

Here, V1 denotes a maximum voltage of the input voltage, and V2 denotes a voltage stored in the charge storage circuit unit 100. [

In the case of a conventional LED lighting device not including the charge storage circuit portion 100, the LED channel may be operated in sequence according to the magnitude of the input voltage, and the flicker phenomenon may occur severely.

However, since the charge storage circuit unit 100 is included in the present invention, the flicker phenomenon can be reduced by supplying more than a constant voltage V2 to the LED unit 30 rather than the conventional LED lighting apparatus.

For example, assuming that the voltage V1 is the minimum voltage level at which the second LED channel 32 can operate, in the LED illumination device including the circuit for reducing the flicker phenomenon of the present invention, The first LED channel 31 and the second LED channel 32 always operate regardless of the magnitude of the input voltage.

That is, in the conventional LED lighting device, the first LED channel 31 and the second LED channel 32 in the section A perform or not operate according to the magnitude of the input voltage. Thus, the first LED channel 31 and the second LED The flicker phenomenon by the channel 32 occurs. However, in the present invention, since the first LED channel 31 and the second LED channel 32 operate simultaneously in A, the first LED channel 31 and the second LED channel 31 The flicker phenomenon by the LED channel 32 does not occur.

However, in the section B, the flicker phenomenon by the third LED channel 33 and the fourth LED channel 34 occurs like the conventional LED lighting apparatus.

The LED lighting apparatus of the present invention having the above-described configuration has the following advantages.

① Switching of FET switch can be performed automatically according to input voltage without configuring input voltage sensing circuit or input period sensing circuit.

(2) Since the switch circuit can be configured easily, extra LED channels can be added for the same area.

(3) By rearranging the forward voltage Vf for each LED channel, it is possible to increase the efficiency of the switch circuit and to perform a combination of free LEDs.

(4) A charge storage circuit is provided to supply the stored charge to the LED unit, thereby supplying a voltage to an LED channel that can not operate at a low voltage, thereby performing the operation, thereby reducing the flicker phenomenon.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the following claims And changes may be made without departing from the spirit and scope of the invention.

10: power supply unit 20: rectifying circuit unit
30: LED part 31, 32, 33, 34: LED channel
35: Resistor section 40: Switch circuit section
41, 42, 43, 44, 45: Switch 50: Current sensing resistance
100: charge storage circuit part 101: first capacitor
102: resistor 103: second diode
104: second capacitor 105: first diode
106: Third diode 200: LED operating part

Claims (7)

A power supply unit for supplying input power;
A rectifier circuit unit receiving the input power from the power unit and outputting rectified rectified power;
A charge storage circuit part for receiving a power from the rectifier circuit part to store a charge when the voltage is a high voltage and discharging a stored charge when the voltage is a low voltage;
An LED unit having a plurality of LED channels connected in series and a resistor unit connected to a last end of the LED channel;
Current sensing resistance: and
And the nth switch is connected to the rear end of the nth LED channel to control the operation of the LED channel, and the current of the nth switch flowing in the current sensing resistor and the current of the n + 1th switch A switch circuit portion in which an nth switch is controlled by the sum of the nth switches; And a circuit for reducing the flicker phenomenon.
The method according to claim 1,
Wherein the resistor unit is connected to the last switch of the switch circuit unit, and the resistor unit distributes and reduces the heat generated in the switch circuit unit, thereby reducing the flicker phenomenon.
The method according to claim 1,
Characterized in that the LED channel comprises at least one LED. ≪ Desc / Clms Page number 13 >
The method according to claim 1,
And the plurality of LED channels have different forward voltages (Vf) to reduce power consumption occurring in the respective switches.
The method according to claim 1,
and the saturation current of the (n + 1) th switch is set higher than that of the nth switch.
The method according to claim 1,
The voltage across the current sensing resistor is changed by the sum of the currents flowing through the neighboring n-th switch and the n + 1-th switch,
And the nth switch is turned off when the input voltage is equal to or greater than the forward voltage Vf of the (n + 1) th LED channel and a saturation current flows through the (n + 1) th switch. And an LED lighting device including a circuit.
The method according to claim 1,
Wherein the charge storage circuit portion includes a first capacitor, a second capacitor, a first diode, a second diode, and a third diode, the second diode is connected in a forward direction between the first capacitor and the second capacitor, One end of the first capacitor is connected to the power supply voltage node of the rectifier circuit part and the other end of the second capacitor is connected to the ground, the first diode is connected to the node between the first capacitor and the second diode, And the third diode is connected between a node between the second capacitor and the second diode and the LED unit so that the voltage output from the rectifying circuit unit is stored in the charge storage circuit unit And the voltage is supplied to the LED unit by emitting a stored charge when the voltage becomes lower than the voltage LED lighting device including a circuit for reducing the Kerr phenomenon.

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