KR20110008437A - Apparatus for supplying power of light emitting diode - Google Patents

Abstract

PURPOSE: A power supplying apparatus for a light emitting diode is provided to add a voltage, which is obtained from a smoothing operation with respect to a current charging an inductor, and another voltage, which is separately extracted alternating current component from a current charging the inductor, and supply the added voltage as an output voltage. CONSTITUTION: A current supplying part(100) supplies a current by being charged from an input voltage. A switching part(200) controls the charging time and the current supplying time of the current supplying part. A first transferring part(300) transfers a current from the current supplying part to a first smoothing part(400). The first smoothing part offers the voltage which is charged with the current delivered with the first conveying section and supplies a smoothed voltage.

Description

Power supply for light emitting diodes {Apparatus for supplying Power of Light Emitting Diode}

Embodiments relate to a power supply for a light emitting diode.

In general, a liquid crystal display device includes two display plates with an electric field applying electrode and a liquid crystal layer having dielectric anisotropy disposed therebetween. A voltage is applied to the field applying electrode to generate an electric field in the liquid crystal layer, and the voltage is changed to adjust the intensity of the electric field to adjust the transmittance of light passing through the liquid crystal layer to display a desired image.

Since the liquid crystal display does not emit light by itself, a separate light source called a backlight is required, and the backlight includes a light emitting diode (LED), a cold cathode fluorescent lamp (CCFL), and an external electrode. Fluorescent lamps (EEFL) and the like are used.

The above-described cold cathode fluorescent lamps or external electrode fluorescent lamps consume a lot of power and may deteriorate characteristics of the liquid crystal display due to heat generation. In addition, since the cold cathode fluorescent lamp or the external electrode fluorescent lamp described above is usually manufactured in a rod shape, it is weak to shock, has a high risk of breakage, and the brightness is different for each lamp position because the temperature is not constant according to the lamp position. May deteriorate color reproducibility.

On the other hand, since the light emitting diode is a semiconductor element, it has a long lifetime, fast lighting speed, low power consumption, and excellent color reproducibility. In addition, it is resistant to impact and is advantageous for miniaturization and thinning.

Therefore, backlights using light emitting diodes are being installed in medium and large liquid crystal display devices such as computer monitors and TVs as well as small liquid crystal display devices such as mobile phones.

A large number of light emitting diodes are employed in the backlight, and a DC-DC converter is used to supply power to the plurality of light emitting diodes.

However, the conventional light emitting diode DC-DC converter has a problem that the peak current applied to electronic devices such as an inductor, a diode, a capacitor, and a MOS transistor constituting the DC-DC converter is high due to a high boost ratio.

The LED power supply device according to the embodiment may smooth the current provided by charging the inductor and the AC component separately extracted from the current provided by charging the inductor, and then smooth and provide the output voltage.

In one embodiment, a power supply for a light emitting diode includes: a current providing unit charged with an input voltage to provide a current, a switching unit adjusting a charging time and a current providing time of the current providing unit, and the current providing unit A first transfer unit for delivering a provided current and suppressing the current from flowing back to the current providing unit or back to the switching unit, and a first charged to provide a smoothed voltage by the current delivered by the first transfer unit A smoothing unit, a second transfer unit which transfers the smoothed voltage provided by the first smoothing unit and suppresses the current caused by the smoothed voltage from flowing back to the first peaceful unit, among the currents provided by the current providing unit An alternating current transfer unit for transmitting only an alternating current, the smoothed voltage transmitted by the second transfer unit and the bridge A third transfer unit which transfers an alternating current delivered by the transfer unit and suppresses the current caused by the smoothed voltage or the AC current from flowing back into the AC transfer unit, and a smoothed voltage transferred by the third transfer unit; And a second smoothing unit charged with the alternating current to provide a smoothed voltage.

According to embodiments, a power supply for a light emitting diode according to embodiments of the present invention adds a voltage obtained by smoothing a current provided by being charged to an inductor and a separately extracted AC component from a current provided by being charged by the inductor, and then smoothes and provides the output voltage as an output voltage. There is an effect that can effectively reduce the peak current applied to the electronic elements constituting the power supply.

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

1 is a circuit diagram of a power supply for a light emitting diode according to an embodiment of the present invention.

Power supply device for a light emitting diode according to an embodiment of the present invention, the current providing unit 100, the switching unit 200, the first transfer unit 300, the first smoothing unit 400, the second transfer unit 500 ), An AC transmission unit 600, a third transmission unit 700, and a second smoothing unit 800 may be configured.

On the other hand, the current providing unit 100 is charged by the input voltage (Vi) to provide a current, it may be specifically configured as an inductor (L).

In addition, the switching unit 200 adjusts the charging time and the current providing time of the current providing unit 100, and specifically, a metal oxide semiconductor field effect transistor (MOS FET) or a bipolar junction transistor (Bipolar Junction Transistor); BJT).

On the other hand, the first transfer unit 300 transfers the current provided by the current providing unit 100 and suppresses the current flowing back to the current providing unit 100 or back to the switching unit 200, specifically It may be composed of a diode (D1).

In addition, the first smoothing unit 400 may be charged by a current transmitted by the first transfer unit 300 to provide a smoothed voltage, and may be specifically configured as a capacitor C1.

On the other hand, the second transfer unit 500 transmits the smoothed voltage provided by the first smoothing unit and suppresses the current caused by the smoothed voltage from flowing back to the first peacemaker, specifically, to the diode D2. Can be configured.

In addition, the AC transfer unit 600 transfers only an AC current among the currents provided by the current providing unit 100, and specifically, may be configured as a capacitor C2.

Meanwhile, the third transfer unit 700 transmits the smoothed voltage delivered by the second transfer unit 500 and the alternating current delivered by the alternating current transfer unit 600, and the current or the alternating current caused by the smoothed voltage. The current is suppressed from flowing back to the AC transfer unit 600, and specifically, may be configured as the diode D3.

In addition, the second smoothing unit 800 is charged by the smoothing voltage transferred by the third transfer unit 700 and the alternating current to provide a smoothed voltage Vo, specifically, as a capacitor CO. Can be configured.

In the LED power supply device according to the exemplary embodiment of the present invention, energy is charged in the current providing unit 100 by a voltage Vi input while the switching unit 200 is turned off, and the switching unit 200 Current is provided by the current providing unit 100 while the current is provided by the first smoothing unit 400 by smoothing the current provided by the current providing unit 100 and the current providing unit 100. Electronic components constituting the power supply device for the light emitting diode according to an embodiment of the present invention by adding the extracted AC component only from the current provided by the second smoothing unit smoothed and provided as the output voltage Vo For example, it is possible to effectively reduce the peak current applied to the inductor, capacitor, diode, MOS transistor, and the like.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments.

Rather, those skilled in the art will appreciate that many modifications and variations of the present invention are possible without departing from the spirit and scope of the appended claims.

Accordingly, all such suitable changes and modifications and equivalents should be considered to be within the scope of the present invention.

1 is a circuit diagram of a power supply for a light emitting diode according to an embodiment of the present invention.

<Description of Signs of Major Parts of Drawings>

100: current providing unit 200: switching unit

300: first transfer unit 400: first smoothing unit

500: second transfer unit 600: AC transfer unit

700: third delivery unit 800: second smoothing unit

Claims (10)

A current providing unit charged with an input voltage to provide a current; A switching unit adjusting a charging time and a current providing time of the current providing unit; A first transfer unit transferring a current provided by the current providing unit and suppressing the current from flowing back to the current providing unit or back to the switching unit; A first smoothing unit charged with a current delivered by the first transfer unit to provide a smoothed voltage; A second transfer unit which transfers the smoothed voltage provided by the first smoothing unit and suppresses the current caused by the smoothed voltage from flowing back to the first peacemaker; An alternating current transfer unit for transferring only an alternating current among currents provided by the current providing unit; A third transmission that transfers the smoothed voltage delivered by the second transfer section and the alternating current delivered by the alternating current transfer section, and suppresses the current caused by the smoothed voltage or the alternating current from flowing back into the alternating current transfer section. part; And And a second smoothing unit configured to provide a smoothed voltage transferred by the third transfer unit and a smoothed voltage by the alternating current. The method of claim 1, The current supply unit includes a power supply for a light emitting diode comprising an inductor. The method of claim 1, The switching unit includes a metal oxide semiconductor field effect transistor (MOS FET) power supply for a light emitting diode. The method of claim 1, The switching unit includes a bipolar junction transistor (BJT) power supply for a light emitting diode. The method of claim 1, The first power supply unit for a light emitting diode comprising a diode. The method of claim 1, The first smoothing unit includes a capacitor. The method of claim 1, The second power supply unit for a light emitting diode comprising a diode. The method of claim 1, The AC transfer unit is a power supply for a light emitting diode comprising a capacitor. The method of claim 1, The third power supply unit for a light emitting diode comprising a diode. The method of claim 1, The second smoothing unit includes a capacitor.

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