KR20100066061A - Apparatus for supplying power of light emitting diode - Google Patents

Abstract

PURPOSE: An apparatus for supplying power of a light emitting diode is provided to linearly control the brightness of a light emitting diode by individually controlling a plurality of light emitting diodes. CONSTITUTION: In an apparatus for supplying power of a light emitting diode, a voltage rectifying unit(100) rectifies an AC voltage into a DC voltage. A voltage converter(200) converts the rectified voltage into a predetermined voltage. At least one light emitting diode(LD1-LD5) is turned on by the voltage provided from the voltage converter. At least one switching element(Q11-Q15) is respectively or alternatively parallel-connected to more than one light emitting diode.

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.

However, a plurality of light emitting diodes are used for such a backlight, and since the plurality of light emitting diodes cannot be individually controlled, there is a problem in that the brightness of the light emitting diodes cannot be adjusted linearly.

The LED power supply device according to the embodiment may linearly adjust the brightness of the LEDs by individually controlling a plurality of LEDs.

In one embodiment, a power supply for a light emitting diode includes a voltage rectifying unit rectifying an input AC voltage into a DC voltage, a voltage converting unit converting the rectified voltage into a predetermined voltage, and a voltage provided by the voltage converting unit. And at least one light emitting diode turned on by the at least one light emitting diode and at least one switching element connected to each of the at least one light emitting diode in parallel or alternately.

The power supply for LEDs according to the embodiments has the effect of linearly adjusting the brightness of the LEDs by individually controlling at least one LED.

In addition, the power supply device for a light emitting diode according to the embodiment is disposed on any one of the at least one light emitting diode, a red light emitting diode or a blue light emitting diode or a green light emitting diode and the above-described plurality of light emitting diodes individually controlled to the light emitting diode There is an effect that can effectively adjust the color of the.

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.

The power supply device for a light emitting diode according to an exemplary embodiment of the present invention may include a voltage rectifying unit 100, a voltage converting unit 200, at least one light emitting diode, and at least one switching element.

Meanwhile, as shown in FIG. 1, the voltage rectifying unit 100 rectifies the AC voltage AC inputted by arranging four diodes D1 to D4 to DC voltage.

In addition, the voltage converter 200 converts the voltage rectified by the voltage rectifier 100 into a predetermined voltage, and the voltage converter 200 includes an inductor L1, a MOS transistor Q1, a diode D5, Resistor R1. In detail, the voltage converter 200 converts the voltage rectified by the voltage rectifier 100 in proportion to a duty ratio of the control pulse signal P1 applied to the MOS transistor Q1 to convert at least one voltage into one or more voltages. Provide to the light emitting diode.

Meanwhile, the at least one light emitting diode is turned on by the voltage provided by the voltage converter 200. Here, at least one light emitting diode may be configured by connecting five first to fifth light emitting diodes LD1 to LD5 in series, as shown in FIG. 1, and adjusting the number of light emitting diodes as necessary. .

In addition, at least one switching element is connected to each of the at least one light emitting diode in parallel, and as shown in FIG. 1, the first to fifth switching elements are respectively connected to the five first to fifth light emitting diodes LD1 to LD5. Q11 to Q15 are connected in parallel. Here, the first to fifth switching elements Q11 to Q15 may include a bipolar junction transistor (BJT) or a MOS transistor Metal Oxide Semiconductor Field Effect Transistor; MOSFET).

When the first to fifth switching elements Q11 to Q15 are turned on, no voltage is transmitted to the first to fifth light emitting diodes LD1 to LD5 to which the first to fifth switching elements Q11 to Q15 are connected. , It is turned off. That is, when the first switching element Q11 is turned on, the first light emitting diode LD1 connected to the first switching element Q11 is turned off. Thus, at least one light emitting diode can be controlled individually.

In the power supply device for a light emitting diode according to an embodiment of the present invention, since at least one light emitting diode can be individually controlled by connecting a switching element to the light emitting diode in parallel, the brightness of the light emitting diode can be linearly adjusted.

Meanwhile, any one of the first to fifth light emitting diodes LD1 to LD5 to which the first to fifth switching elements Q11 to Q15 are connected may be a blue light emitting diode, a green light emitting diode, or a red light emitting diode. That is, the first light emitting diode LD1 is disposed as a blue light emitting diode, the third light emitting diode LD3 is disposed as a green light emitting diode, or the fifth light emitting diode LD5 is disposed as a red light emitting diode.

In the power supply for a light emitting diode according to an embodiment of the present invention by placing a blue light emitting diode or a green light emitting diode or a red light emitting diode in any one of the at least one light emitting diode, by controlling at least one light emitting diode individually, The color of the light emitting diode can be adjusted effectively.

A power supply for a light emitting diode according to another embodiment of the present invention will be described with reference to FIG. 2, and the same points as those of the light emitting diode power supply according to an embodiment of the present invention will be omitted. Explain only about.

In a power supply for a light emitting diode according to another embodiment of the present invention, switching elements are alternately connected in parallel to at least one light emitting diode.

That is, as shown in FIG. 2, switching elements Q22 and Q24 are connected in parallel to each of the even-numbered light emitting diodes LD2 and LD4. If necessary, switching elements may be connected in parallel to every three light emitting diodes, and switching elements may be connected in parallel to every four light emitting diodes.

Meanwhile, any one of the light emitting diodes LD2 and LD4 to which the switching elements Q22 and Q24 are connected is a blue light emitting diode, a green light emitting diode, or a red light emitting diode.

The power supply device for a light emitting diode according to another embodiment of the present invention can be easily configured by alternately connecting switching elements to at least one light emitting diode in parallel, and can linearly adjust the brightness of the light emitting diode.

In addition, a power supply for a light emitting diode according to another embodiment of the present invention also effectively adjusts the color of the light emitting diode by arranging a blue light emitting diode, a green light emitting diode or a red light emitting diode on any one of the light emitting diodes to which the switching element is connected. Can be.

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, it will be apparent to those skilled in the art that many changes and modifications to 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.

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

<Description of Signs of Major Parts of Drawings>

100: voltage rectifier 200: voltage converter

Claims (6)

A voltage rectifier for rectifying the input AC voltage into a DC voltage; A voltage converter converting the rectified voltage into a predetermined voltage; At least one light emitting diode turned on by a voltage provided by the voltage converter; And And at least one switching element connected to each of the at least one light emitting diode in parallel or alternately. The method of claim 1, The at least one switching element includes a bipolar junction transistor (BJT). The method of claim 1, The at least one switching element includes a MOS transistor (Metal Oxide Semiconductor Field Effect Transistor; MOSFET). The method of claim 1, Any one of the at least one light emitting diode comprises a red light emitting diode. The method of claim 1, Any one of the at least one light emitting diode includes a blue light emitting diode power supply. The method of claim 1, Any one of the at least one light emitting diode comprises a green light emitting diode.

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