KR101299360B1 - Led driving circuit for regulating the drive currents of a plurality of led - Google Patents

Abstract

PURPOSE: An LED lighting driver circuit controls current driving characteristics of each current channel by individually installing ground resistors on each current channel of an AC direct type LED driver circuit, randomly setting a voltage value at the individual ground resistor, and controlling a switching element of a previous channel based on a set threshold voltage value of each ground resistor. CONSTITUTION: An LED lighting driver circuit having a current supply control function by LED includes a power unit (110) including a power supply unit which receives external AC power and a rectifier circuit of AC power applied through the power supply unit; an LED lighting unit (120) which includes a first LED located at the shortest distance from a connection point with the power unit to an n-th LED located at the longest distance from the power unit, and in which the first LED is connected to the power unit and the LEDs are connected to each other in series; multiple switching circuit units (130) connected to an output terminal of the LED, forming a current supply channel for the corresponding LED and individually including a ground resistor; and a switching circuit control unit (140) individually connected to the switching circuit unit and turning off the previous switching circuit unit relatively adjacent to the power unit when a voltage value at the ground resistor exceeds a set threshold voltage value.

Description

LED driving circuit for regulating the drive currents of a plurality of LEDs

The present invention relates to an LED lighting driving circuit having a current supply control function for each LED. In particular, the ground resistance is individually installed in each current channel of the AC direct type LED driving circuit, and the voltage value applied to the individual ground resistance is arbitrarily set. The LED lighting driving circuit has a current supply control function for each LED that can freely adjust the current driving characteristics of each current channel by controlling on / off of the switching element of the previous channel based on the set threshold voltage value of each ground resistance. It is about.

LED (Light Emitting Diode) is a current driving device, and can be operated normally if a constant current is supplied stably. In particular, LEDs requiring high power have a large driving current (typically, 350 mA or more), so that the LED itself generates a lot of heat, and therefore, the deterioration rate of brightness is larger than that of LEDs at low power. This is directly linked to the lifetime of the LED and is very important in the lighting market.

Initially, LED lighting is implemented as a buck type of a switched mode power supply (SMPS), and recently, an AC direct driving method of LED lighting, which dramatically reduces the number of reactive components, has been proposed and implemented.

In the AC direct driving method of LED lighting, AC power is directly applied to the heat of the LED, and a number of LEDs suitable for the voltage value of the AC power that changes in time is selected, and then the current source is arranged in parallel so that only the selected LED is turned on. That's the way. This is essentially by placing multiple current sources between the intermediate nodes of the LEDs in series and ground, thereby actively controlling the number of LEDs that are turned on to match the magnitude of the input AC voltage.

The AC direct LED lighting driving circuit is conceptually described. An AC direct LED lighting driving circuit includes an AC power supply, a power supply unit including a dimmer and a rectifier, an operation control unit, a plurality of LEDs, and a current source corresponding to the number of such LEDs. It is composed of a drive unit including a. The operation control unit receives the full-wave rectified AC voltage generated from the power supply unit, and controls the lighting and blinking of the corresponding current source when the input AC voltage reaches a preset value.

1 is a view showing an example of a conventional AC direct type LED driving circuit, Figure 2 is a view showing a current waveform of the AC direct type LED driving circuit according to FIG.

As described above, the AC direct type LED driving circuit of FIG. 1 includes an AC power source 11, a power supply unit 10 including a dimmer 12, and a rectifier rectifier 13, and a plurality of LEDs 21 to 26. And a current source 30 connected to the lighting unit 20 and the LED output terminal of the LED lighting unit 20.

Here, AC direct type LED driving circuit operates in the order of OPA1, OPA2, OPA3 when the VAC voltage increases when the condition of V1 <V2 <V3 is satisfied, and OPA3, OPA2, OPA1 when the VAC voltage decreases. And thus the current control is in the form of FIG. 2.

That is, FIG. 2 shows a current waveform according to voltage when the AC direct type LED driving circuit according to FIG. 1 is driven. In this case, since the condition of V3> V2> V1 must be satisfied, the current waveform has a stepped shape with an increased center. It becomes a waveform.

However, this is an obstacle when designing an AC direct type LED driving circuit to have a current value of a different shape or size according to the use. In other words, when designing the AC direct type LED driving circuit, it is limited by the condition of 'V3> V2> V1'.

Korean Patent No. 10-1175934 (2012.08.16), "Light Emitting Diode Driving Circuit and AC Direct Light Emitting Diode Lighting Device Using the Same" Korean Patent Registration No. 10-1157670 (2012.06.12), “Method of Controlling the Operation of Switching Power Converter by Eliminating Redundancy of Transistors”

The present invention separately installs the grounding resistors in each current channel of the AC direct type LED driving circuit and arbitrarily sets the voltage value applied to the individual grounding resistors, while simultaneously switching the switching elements of the previous channel based on the set threshold voltage values of the respective grounding resistors. It is an object of the present invention to provide an LED lighting driving circuit having a current supply control function for each LED, which can freely adjust the current driving characteristics of each current channel through an on / off control method.

In order to achieve the above object, an LED lighting driving circuit having a current supply control function for each LED according to the present invention includes a power supply unit to which external AC power is supplied and a rectifier circuit of AC power applied through the power supply unit. The first LED is connected to the power supply unit, including the power supply unit and the nth LED located at the longest distance from the power supply unit, including the first LED located at the shortest distance from the connection point with the power supply unit. A plurality of switching circuits individually connected to an LED lighting unit, an output terminal of each LED forming the LED lighting unit to form a current supply channel for the corresponding LEDs, and each of which has a grounding resistance; When the voltage value applied to the resistance exceeds a preset threshold voltage value, the power supply is relatively close to the power supply. A is configured to include a switching circuit control section for previously off the switching circuit portion.

The power supply unit may further include a dimmer connected to the power supply unit to receive an AC voltage and to apply an output voltage to the rectifier circuit.
The switching circuit unit may include a switching element connected to the LED output terminal of the LED lighting unit and a first comparator for comparing the reference voltage for the LED of the LED lighting unit with a voltage value applied to the ground resistance. The switching circuit controller is connected to an output line of the switching element in parallel to input a voltage value applied to the ground resistance, and compares the input voltage value of the ground resistance with a preset threshold voltage value of the ground resistance. And an inverting buffer connected to an output terminal of the second comparator, a first switch connected in series to a connection line between the output terminal of the first comparator and the switching element, and a second switch connected in parallel to the connection line between the first switch and the switching element. The first switch and the second switch including the second switch is the output of the second comparator or inverting buffer It is characterized in that the on / off by the output signal.

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The switching element may be a field effect transistor (MOS FET) having a drain connected to an LED output terminal of the LED driver, a source connected to the ground resistor, and a gate connected to the comparator.

The switching circuit unit may be connected to all LED output terminals of the LED lighting unit individually or to an LED output terminal located farthest from the power supply unit of each LED group for each LED group formed by connecting two or more LEDs in series. It is done.

According to the present invention, the ground resistance is individually installed in each current channel of the AC direct type LED driving circuit, and the voltage value applied to the individual ground resistance is arbitrarily set, while switching the previous channel based on the set threshold voltage value of each ground resistance. By controlling the device on and off, the current driving characteristics of each current channel can be freely adjusted.

1 is a view showing an example of a conventional AC direct type LED driving circuit
2 is a view showing a current waveform of the AC direct type LED driving circuit according to FIG.
3 is a view showing the LED lighting driving circuit having a current supply control function for each LED according to an embodiment of the present invention
4 is a view showing the current waveform of the LED lighting driving circuit having the LED-specific current supply control function according to FIG.

Hereinafter, with reference to the accompanying drawings will be described in detail an LED lighting driving circuit having a current supply control function for each LED according to an embodiment of the present invention.

3 is a view showing an LED lighting driving circuit having a current supply control function for each LED according to an embodiment of the present invention.

As shown, the LED lighting driving circuit 100 (hereinafter referred to as "LED lighting driving circuit") having the LED-specific current supply control function according to the present invention, the power supply unit 110, LED lighting unit 120, switching circuit unit ( 130, the switching circuit controller 140 is configured.

The power supply unit 110 includes a power supply unit 111 and a rectification circuit 112. The power supply unit 110 may further include a dimmer 113. The power supply unit 111 is connected to an external AC power source (AC power source, hereinafter referred to as an 'AC power source') to receive the AC power source, and the rectifier circuit 112 receives AC power supplied through the power source unit 111 Rectify. The dimmer 113 is connected in series to the connection line between the power supply unit 111 and the rectification circuit 112 and receives the AC voltage from the power supply unit 111 and then applies the output voltage to the rectification circuit 112. Here, the dimmer 113 may be selected from any one of ordinary dimmers, and therefore, a detailed description thereof will be omitted in the present embodiment.

The LED lighting unit 120 includes a plurality of LEDs 120-1 to 126, that is, the first LED 121 and the first LED 121 positioned at the shortest distance from the connection point with the power supply unit 110. First, the sixth LED 126 is positioned at the longest distance from the power supply 110. In this embodiment, the LED lighting unit 120 has a form in which six LEDs are included from the first LED 121 to the sixth LED 126, but the present invention is not limited thereto. May be formed in various numbers within a range satisfying a condition including two or more LEDs.

The first LED 121 is electrically connected to the power supply unit 110, and all of the LEDs 121 to 126 included in the first LED 121 and the lighting unit 120 are connected to each other in series.

The switching circuit unit 130 is connected to an output terminal of the LEDs 121 to 126 forming the LED lighting unit 120, and each of these switching circuit units 130 forms a current supply channel for the corresponding LEDs 121 to 1206. In addition, each of the switching circuits 130 includes a grounding resistor 133 separately. In the present exemplary embodiment, two LEDs form a group so that the switching circuit unit 130 is connected to an output terminal of the LED relatively far from the power unit of each group, but the present invention is not limited thereto. The 130 may be individually connected to the output terminals of all LEDs 121 to 126 of the LED lighting unit 120 or may be connected to the LED output terminals relatively far from the power units of each group for each group formed of three or more LEDs. Can be.

The switching circuit unit 130 includes a switching element 131 and a first comparator 132, and the switching element 131 is connected to the LED output terminal of the LED driver 120 and is connected to the ground resistor 133. The first comparator 132 compares the reference voltage in the LED lighting driving circuit 100 with the voltage of the ground resistor 133. In addition, the switching element 131 may include a first current path connected to the LEDs 121 to 126 of the LED driver 120 and a second current path connected to the ground resistor 133 according to the output of the first comparator 132. Switch to either side.

In this embodiment, the switching element 131 has a field effect transistor having a drain connected to the LED output terminal of the LED lighting unit 120, a source connected to the ground resistor 133, and a gate connected to the first comparator 132. MOS FET), but the present invention is not limited thereto.

The switching circuit control unit 140 is connected to the switching circuit unit 130 separately, and when the voltage value applied to the ground resistor 13 exceeds a preset threshold voltage value, the switching circuit control unit 130 relatively close to the power supply unit 110 may be used. Turn it off.

Referring to the drawings, when the voltage value applied to the ground resistance R3 of the switching circuit controller 140 connected to the switching circuit unit 130 of the sixth LED output terminal 126 exceeds the preset threshold voltage value, the fourth LED 124 is connected. The switching circuit unit 130 connected to the output terminal of is turned off. In addition, the switching circuit controller 140 connected to the switching circuit unit 130 of the output terminal of the fourth LED 124 is connected to the output terminal of the second LED 124 when the voltage value applied to the ground resistance R2 exceeds a preset threshold voltage value. Off the switched circuit unit 130.

The switching circuit controller 140 includes a second comparator 141, an inverting buffer 142, a first switch 143, and a second switch 144.

The second comparator 141 is connected in parallel to the output line of the switching element 131 and the voltage value applied to the ground resistor 133 is input. Accordingly, the second comparator 141 receives the voltage of the ground resistor 133 input thereto. The value is compared with a predetermined threshold voltage value of the ground resistor 133 and outputs a control signal for turning off the first and second switches 143 and 144 according to the comparison result.

The inverting buffer 142 is connected to the output terminal of the second comparator 141, and the inverting buffer 142 turns on the first and second switches 143 and 144 according to the output signal of the second comparator 141. Outputs a control signal.

The first switch 143 is connected in series to the connection line between the output terminal of the first comparator 132 and the switching element 131.

The second switch 144 is connected in parallel to the connection line between the first switch 143 and the first switch 143 and the switching element 131.

Accordingly, the first switch 143 and the second switch 144 are turned on / off by the output signal of the second comparator 141 or the inverting buffer 142.

By the configuration of the switching circuit controller 140 as described above, the currents I ₁ , I ₂ , and I ₃ of each current channel have values of V1 / R1, V2 / R2, and V3 / R3, respectively. In the LED driving circuit, the current driving characteristics of each current channel of the LED lighting driving circuit 100 may be freely adjusted regardless of whether the LED driving circuit is restricted due to the conditions of V3>V2> V1. This can also be confirmed through FIG. 4.

Figure 4 is a view showing the current waveform of the LED lighting driving circuit having a current supply control function according to the LED according to Figure 3, LED lighting driving circuit so as to clearly contrast with the step-shaped current waveform of the conventional AC direct type LED driving circuit according to FIG. This corresponds to an example in which the current driving characteristic of the furnace 100 by the current channel is designed in an extreme form.

As can be seen from the description of the embodiment with reference to FIGS. 3 and 4 described above, the LED lighting driving circuit having the LED-specific current supply control function according to the present invention, the ground resistance to each current channel of the AC direct type LED driving circuit It is possible to freely control the current driving characteristics of each current channel by individually installing and arbitrarily setting the voltage value applied to the individual ground resistors, and controlling the switching elements of the previous channel on / off based on the set threshold voltage value of each ground resistor. Make it adjustable.

What has been described above is only one embodiment for implementing the LED lighting driving circuit having the LED-specific current supply control function according to the present invention, the present invention is not limited to the above-described embodiment, in the following claims As claimed, any person having ordinary skill in the art without departing from the gist of the present invention will have the technical spirit of the present invention to the extent that various modifications can be made.

100: LED driving circuit 110: power supply
111: power supply unit 112: rectifier circuit
113: dimmer 120: LED lighting part
121 ~ 126: LED 130: switching circuit
131: switching element 132: first comparator
133: grounding resistance 140: switching circuit
131: switching element 132: comparator
133: ground resistance 140: switching circuit control
141: second comparator 142: inverting buffer
143: first switch 144: second switch

Claims (5)

A power supply unit including a power supply unit to which an external AC power is supplied and a rectification circuit of an AC power supply to be applied through the power supply unit;
An LED lighting unit including an n-th LED located at a longest distance from a power source, the first LED being located at a shortest distance from a connection point with the power source unit, the first LED being connected to the power source unit and each LED being connected in series;
A plurality of switching circuit units connected to an output terminal of the LED forming the LED lighting unit to form a current supply channel for the LED, and each having a ground resistance;
And a switching circuit control unit which is individually connected to the switching circuit unit and turns off the previous switching circuit unit relatively close to the power supply unit when the voltage value applied to the ground resistance exceeds a preset threshold voltage value. LED lighting driving circuit. The method of claim 1,
And the power supply unit further includes a dimmer connected to the power supply unit to receive an AC voltage and to apply an output voltage to the rectifier circuit. 3. The method according to claim 1 or 2,
The switching circuit unit includes a switching element connected to the LED output terminal of the LED lighting unit and connected to the ground resistance and a first comparator for comparing a reference voltage for the LED of the LED lighting unit with a voltage value applied to the ground resistance,
The switching circuit controller is connected to an output line of the switching element in parallel and a voltage value applied to the ground resistance is input, and a second comparator for comparing the voltage value of the input ground resistance with a predetermined threshold voltage value of the ground resistance; An inverting buffer connected to the output terminal of the second comparator and a first switch connected in series to the connection line between the output terminal of the first comparator and the switching element and a second switch connected in parallel to the connection line between the first switch and the switching element LED lighting driving circuit having a current supply control function for each LED, characterized in that the first switch and the second switch is turned on / off by the output signal of the second comparator or inverting buffer. The method of claim 3, wherein
The switching element is a field effect transistor (MOS FET) characterized in that the drain is connected to the LED output terminal of the LED lighting unit, the source is connected to the ground resistor, the gate is connected to the first comparator (MOS FET) LED lighting driving circuit having a. 3. The method according to claim 1 or 2,
The switching circuit unit may be connected to all LED output terminals of the LED lighting unit individually or to the LED output terminal located farthest from the power unit of each LED group for each LED group formed by two or more LEDs connected in series. LED lighting driving circuit having a current supply control function for each LED.

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