KR20100111506A - Led power supply unit - Google Patents

Abstract

PURPOSE: An LED power supply device is provided to obtain directivity of the light and to reduce the power consumption by supplying the LED with the constant current using a constant current generation circuit. CONSTITUTION: A power unit(110) supplies an LED lighting unit(120) with the power. The power unit comprises a constant current unit(114) and a capacitor(C1) for sustaining the DC voltage constant. A constant current unit rectifies the alternating current power into DC voltage using a bridge diode. The capacitor removes the alternating component present in the DC component.

Description

LED Power Supply Unit {LED POWER SUPPLY UNIT}

The present invention relates to an LED control device, and more specifically, to drive the LED with a constant current generating circuit portion, LED power supply that can secure the disadvantages of conventional fluorescent lamps and bar-type lighting, such as power saving, eco-friendliness, lighting life It is about.

Recently, there has been extraordinary interest in eco-friendly and carbon dioxide emissions, energy saving, and the like. In particular, in order to reduce the use of coal fuel, which emits large amounts of carbon dioxide, it is concentrating on developing alternative energy such as solar power, wind power, and grain fuel.

Among existing luminaires used in homes, offices, and factories, filament lighting devices generate heat by heat, and the product itself generates a lot of heat and its life is very short due to oxidation of the filament. In addition, many conventional fluorescent lamp products using fluorescent materials also have a short lifespan, and the fluorescent materials pollute the atmosphere when disposed.

Neon signs are also short-lived, expensive to manufacture and replace, and the gas in the tube contains mercury, which pollutes the environment. In addition, the above lighting devices have the disadvantage of high power consumption.

Therefore, in order to use LED lighting in addition to the existing lighting devices such as incandescent lamps and fluorescent lamps, LED modules for lighting are used in many areas, for example, at home other than products related to places such as traffic lights, street lighting landscape lights, and vehicle lights. It is used in flashlights, stand lights and indirect lighting for some specific purposes.

1 shows a circuit of a conventional lighting LED module, and generates various DC power sources from a switching mode power supply (SMPS) 1 to drive a load circuit.

Such a conventional lighting LED module device has a compensating circuit (2) in the driving constant power source because the voltage fluctuates depending on the connection method due to the characteristics of the LED on the load side, and a high capacity compensation filter (capacity bank (3) in front of the load block. However, since the LED is an individual device and the characteristics of each LED device are different, the fundamental problem is not solved. This cannot be solved by including a problem such as an error in device characteristics generated in the production of LED devices.

The SMPS is to level the AC power by rectifying the DC power through the rectifier diode and then to make the required DC power through the chopping oscillation. Over will result in a drastic change in the power source. In addition, many components such as semiconductor switching elements are required in the power conversion circuit, which causes a cost increase.

In addition, in the LED module that is the load, when the current intensity drops below a certain percentage of the nominal current intensity at the driving voltage of one input power source, the relation between the current intensity and the LED light output for illumination, which is the driving load, becomes more non-linear. The light efficiency of the LED module is not optimized at all. In other words, the lighting LED device is accompanied by a high temperature due to a rapid current change, the device is destroyed, or a sudden change in the light output appears as a failure of the device. This problem develops to the failure of the LED load due to the uneven load power, and the life of the LED components is also drastically reduced.

In addition, the lighting LED module is generally composed of a high-brightness light emitting diode, the semiconductor light emitting device is generally known to change the emission intensity over time or temperature change if the optimal driving power is not received. For example, it is known that the light output decreases with the deterioration of the semiconductor light emitting device as time passes, and even if the drive power is supplied to produce a constant light output, If any one of the abnormalities occurs, the temperature rises with deterioration of the semiconductor light emitting device, and the life is shortened. Also, if the temperature increases, the threshold current increases in the LED lamp for lighting and the same light emission output is obtained. This becomes necessary problem.

When the change or change in the light emission output accompanied by the instantaneous power change or temperature change according to the elapsed time of the semiconductor light emitting device occurs, the light intensity or color unevenness may occur in the case of a display or a light emitting diode.

An object of the present invention for solving this problem is to provide an LED power supply that can supply a stable current to the LED (light-emitting diode) using a constant current generating circuit portion,

LED power supply apparatus according to an embodiment of the present invention for achieving this object is a plurality of LED light emitting unit connected in series and in parallel, a power supply for supplying power to the LED light emitting unit and a constant current to the LED light emitting unit It may be configured to include a constant current generating circuit unit connected in series with the power supply unit to supply.

The constant current generating circuit unit is composed of a plurality of switching elements to control the value of the current through the internal resistance value according to the load capacity of the LED light emitting unit, and form a negative feedback with two transistors, respectively, conduction by the emitter resistance and the base resistance It is characterized in that it is configured to be biased.

When the AC power source is used, the power supply unit may include a rectifier for converting an AC voltage into a DC voltage and a smoothing capacitor for maintaining a constant DC voltage of the rectifier.

Therefore, according to the LED power supply of the present invention, by supplying a constant current to the LED, the power consumption can be reduced to about 50% compared to the existing fluorescent lamp, long life of 35,000 ~ 50,000 hours, clear visibility due to the straightness of light, There is an environmentally friendly effect that does not use harmful substances such as mercury, fluorescent materials, reducing the damage caused by the ultraviolet rays are not emitted.

And, energy saving and long life, there is an effect that can be produced environmentally friendly lighting equipment.

The terms or words used in this specification and claims are not to be construed as limiting in their usual or dictionary meanings, and the inventors may properly define the concept of terms in order to best explain their invention in the best way possible. It should be interpreted as meaning and concept corresponding to the technical idea of the present invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

2 is a block diagram of an LED power supply device according to an embodiment of the present invention, the LED power supply device 100 includes a power supply unit 110, LED light emitting unit 120 and the constant current generating circuit unit 130 do.

When the AC power source 110 is used to supply the DC voltage for driving the LED light emitting unit 120, the power supply unit 110, the rectifier 114 for converting the AC voltage into a DC voltage, and the DC voltage constant It can be configured as a smoothing capacitor (C1) to keep it, but may be omitted when using a DC power source.

3 is a block diagram of an LED power supply device according to another embodiment of the present invention, and shows a configuration diagram when a DC voltage is used as the power supply unit 110.

Therefore, the same structure is demonstrated using the same code | symbol.

The rectifier 114 rectifies and outputs a commercial AC power using a bridge diode and outputs the DC voltage. The DC voltage is smoothed by the smoothing capacitor C1 to the LED light emitting unit 120 and the constant current generating circuit unit 130. Is approved.

The smoothing capacitor C1 is composed of an electrolytic capacitor and is used to stabilize the DC power supply by removing the AC component present in the DC component.

That is, the smoothing capacitor C1 receives the DC power output from the rectifying unit 114 as shown in FIG. 2 and reduces the pulse flow remaining in the DC voltage, so that the LED driver 120 emits light stably without flickering. Be sure to

The LED light emitting unit 120 is composed of a plurality of LEDs combined in series and in parallel, and receives a constant current by the rectifying unit 110 and the constant current generating circuit unit 130 to emit a constant light. In addition, the LED light emitting unit 120 may adjust the brightness of the light by the addition or subtraction of the LED connected in series or in parallel.

The constant current generation circuit unit 130 includes a plurality of semiconductor switching elements and resistors to control the value of the current through the internal resistance value according to the load capacity of the LED light emitting unit 120.

Specifically, the constant current generating circuit unit 130 forms negative feedback with two transistors TR1 and TR2, and is electrically connected by the resistor R1 (hereinafter referred to as emitter resistor) and the resistor R2 (hereinafter referred to as base resistor). Configured to bias as much as possible.

2 and 3, the voltage of the smoothing capacitor C1 minus the voltage applied to the LED light emitting unit 120 is applied to the constant current generating circuit unit 130.

The constant current generating circuit unit 130 is a circuit used as a constant current source after negative feedback to two transistors. When the transistor TR1 is biased by the base resistor R2 and is conducting, a voltage is applied to the emitter resistor R1. When the emitter is caught, TR2 conducts and the base current of TR1 is classified, so that the negative feedback of TR1 decreases and it becomes a constant current source through which current flows constantly.

Specifically, when TR2 is turned on, a voltage V _{B _ sat} of about 0.7V is applied between the base and the emitter of TR2. Since the voltage between the base and emitter of TR2 and the voltage across resistor R1 are the same, current IR1 flows through resistor R1 as shown in [Equation 1].

On the other hand, since the voltage between the collector and emitter of transistor TR2 is equal to the sum of the voltage between the base and emitter of transistor TR1 and the voltage between the base and emitter of transistor TR2, the voltage between the collector and emitter of transistor TR2 can be represented by 2V _BEsat . Therefore, the current flowing through the resistor R2 can be expressed as shown in [Equation 2].

In Equation 2, VC1 denotes a voltage applied to the smoothing capacitor C1 and VLED denotes a voltage applied to both ends of the LED light emitting unit 120. When the current amplification ratios of the transistors TR1 and TR2 are significantly greater than 1, the current flowing through the LED light emitting unit 120 may be represented by the sum of the currents flowing through the resistor R1 and the resistor R2. By appropriately selecting the resistance values of the resistor R1 and the resistor R2, the current flowing through the LED light emitting unit 120 can be distributed at a ratio appropriate for the transistor TR1 and the transistor TR2.

In the constant current generation circuit unit 130 of the present invention, even when the voltage of the smoothing capacitor C1 fluctuates, the two switching elements share the current appropriately, so that the constant current flows in the LED light emitting unit 120 at all times. Therefore, according to the present invention, even when AC voltage, which is an input power source, fluctuates, a constant current flows through the LED light emitting unit 120 to maintain a constant light intensity.

That is, the magnitude of the constant current of the entire circuit is determined by the values of the base resistor R2 and the emitter resistor R _E. Such a constant current generating circuit portion is suitable for charging a Ni-Cd battery or driving an LED lamp operating in a wide voltage range.

3 shows an example of using a DC power supply as another embodiment of the present invention. In the embodiment of FIG. 2, a DC power source such as a battery is used instead of an AC power source, a rectifying unit, and a smoothing capacitor C1 to make a DC voltage, and the operation of the LED light emitting unit 120 and the constant current generating circuit unit 130 of FIG. 2. The principle is the same as that of FIG.

While the invention has been described in detail with respect to the embodiments described, it will be apparent to those skilled in the art that various modifications and variations are possible within the spirit of the invention, and such modifications and variations belong to the appended claims.

1 is a view showing a conventional conventional LED module for lighting,

2 is a block diagram of an LED power supply device according to an embodiment of the present invention;

And,

3 is a block diagram of an LED power supply according to another embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

100: LED power supply 110: power supply

120: LED light emitting unit 130: constant current control unit

Claims (4)

LED light emitting unit; A power supply unit for supplying power to the LED light emitting unit; And A constant current generating circuit unit connected in series with the power supply unit to supply a constant current to the LED light emitting unit; LED power supply configured to include. The method of claim 1, The constant current generating circuit portion LED power supply, characterized in that composed of a plurality of switching elements to control the value of the current through the internal resistance value in accordance with the load capacity of the LED light emitting unit. 3. The method of claim 2, The constant current generating circuit portion The LED lighting device is configured to form a negative feedback with two transistors (TR1, TR2) and to be biased by a base resistor (R2) and an emitter resistor (R1), respectively. The method of claim 1, The power supply unit Rectifier for converting AC voltage to DC voltage; And A smoothing capacitor for maintaining a constant DC voltage of the rectifying unit; LED power supply, characterized in that configured to include.

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