KR101054901B1 - LED drive device - Google Patents

Abstract

The present invention is a first transformer for transforming the voltage input to the primary side to provide to the secondary side, a first switching element connected in parallel to the secondary side of the first transformer, turned on or off by a first control signal, A second switching element connected between the secondary side of the first transformer and the ground and turned on or off by an inverted signal of the first control signal, a plurality of light emitting diodes connected in series and connected to the secondary side of the first transformer A first light emitting diode group, a second transformer for transforming a voltage input to the primary side and providing the secondary to a secondary side, and a third connected in parallel with the secondary side of the second transformer and turned on or off by a second control signal Switching element, a fourth switching element connected between the secondary side of the second transformer and ground, turned on or off by the inverted signal of the second control signal And a second group of light emitting diodes, in which a plurality of light emitting diodes are connected in series and connected to a secondary side of the second transformer, wherein the primary side of the first transformer and the primary side of the second transformer are connected in series, and a closed loop. Provided is a light emitting diode driving apparatus.

LED, liquid crystal display, transformer

Description

Light-emitting diode driving device {Apparatus for driving Light Emitting Diode}

An embodiment relates to a light emitting diode driving apparatus.

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 luminance 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, such a light emitting diode has a problem in that a current is concentrated at an instant and visual noise or audio noise is generated.

The LED driving apparatus according to the embodiment can effectively distribute the current provided to the LED.

The LED driving apparatus according to an embodiment may be connected in parallel to a first transformer and a secondary side of the first transformer for converting a voltage input to the primary side and providing the secondary side, and turned on or off by a first control signal. The first switching element is connected between the secondary side of the first transformer and the ground, the second switching element turned on or off by the inverted signal of the first control signal, a plurality of light emitting diodes are connected in series A first group of light emitting diodes connected to the secondary side of the first transformer, a second transformer for transforming the voltage input to the primary side to provide to the secondary side, connected in parallel to the secondary side of the second transformer, the second control signal A third switching element turned on or off by a third switching element, connected between the secondary side of the second transformer and ground, and turned on by an inversion signal of the second control signal And a second group of light emitting diodes connected to each other or turned off and a plurality of light emitting diodes connected in series and connected to the secondary side of the second transformer, wherein the primary side of the first transformer and the first of the second transformer are connected. The vehicle side is connected in series and a closed loop is formed.

The LED driving apparatus according to another embodiment may be connected in parallel to a first transformer and a secondary side of the first transformer for converting a voltage input to the primary side and providing the secondary side, and turned on or off by a first control signal. The first switching device is connected between the secondary side of the first transformer and the ground, the second switching device turned on or off by the inverted signal of the first control signal, a plurality of light emitting diodes are connected in series A first group of light emitting diodes connected to a secondary side of a first transformer, a second transformer for transforming a voltage input to the primary side and providing the secondary side, and connected in parallel to a secondary side of the second transformer, by a second control signal A third switching element, which is turned on or off, is connected between the secondary side of the second transformer and ground and is turned by an inverted signal of the second control signal Or a fourth switching element that is turned off or turned off, a second group of light emitting diodes connected in series and connected to the secondary side of the second transformer, and a third transformer for transforming a voltage input to the primary side and providing the voltage to the secondary side A fifth switching element connected in parallel to the secondary side of the third transformer, the fifth switching element turned on or off by a third control signal, connected between the secondary side of the third transformer and ground, and inverting the third control signal. A sixth switching element turned on or off by a signal and a plurality of light emitting diodes connected in series and connected to a secondary side of the third transformer; The primary side of the second transformer and the primary side of the third transformer are connected in series and a closed loop is formed.

The LED driving apparatus according to the embodiments includes a separate switching element for each LED group, and by applying a control signal of a different phase to each switching element, it is possible to effectively distribute the current provided to the light emitting diode, Visual noise and audio noise can be suppressed.

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 LED driving apparatus according to an embodiment of the present invention.

As shown in FIG. 1, the LED driving apparatus according to an exemplary embodiment of the present invention includes a first transformer 120, a first LED group 130, a first switching element Q1, and a second switching element Q2. ), The second transformer 220, the second light emitting diode group 230, the third switching element Q3, the fourth switching element Q4, the third transformer 320, and the third light emitting diode group 330. It may be configured to include a fifth switching element Q5 and a sixth switching element Q6.

The first transformer 120 transforms the voltage input to the primary side to provide the secondary side, and the first LED group 130 includes a plurality of LEDs connected in series, and the secondary side of the first transformer 120. It is connected to the power supply voltage Vout.

On the other hand, since the first switching element Q1 is connected in parallel to the secondary side of the first transformer 120 and turned on or off by the first control signal Gate1, it is preferable that the current can flow in both directions. Silicon controlled rectifier (SCR).

In addition, the second switching element Q2 is connected between the secondary side of the first transformer 120 and the ground GND, and turned on or off by an inverted signal of the first control signal Gate1, and the MOS transistor ( Metal Oxide Semiconductor Field Effect Transistors (MOS FETs) or Bipolar Junction Transistors (BJTs). Here, the inverter I1 is for inverting the first control signal Gate1.

The second switching element Q2 is turned off while the first switching element Q1 is turned on, and the second switching element Q2 is turned on while the first switching element Q1 is turned off.

The second transformer 220 transforms the voltage input to the primary side to provide the secondary side, and the second LED group 230 includes a plurality of LEDs connected in series, and the secondary side of the second transformer 220. It is connected to the power supply voltage Vout.

On the other hand, since the third switching element (Q3) is connected in parallel to the secondary side of the second transformer 220, is turned on or off by the second control signal Gate2, it is preferable that the current can flow in both directions, Silicon controlled rectifier (SCR).

In addition, the fourth switching element Q4 is connected between the secondary side of the second transformer 220 and the ground GND, and is turned on or off by the inverted signal of the second control signal Gate2, and the MOS transistor Metal Oxide Semiconductor Field Effect Transistors (MOS FETs) or Bipolar Junction Transistors (BJTs). Here, the inverter I2 is for inverting the second control signal Gate2.

The fourth switching element Q4 is turned off while the third switching element Q3 is turned on, and the fourth switching element Q4 is turned on while the third switching element Q3 is turned off.

The third transformer 320 transforms the voltage input to the primary side and provides the voltage to the secondary side. The third LED group 330 is connected to a plurality of LEDs in series, and the second side of the third transformer 320 is connected to the secondary side. It is connected to the power supply voltage Vout.

On the other hand, since the fifth switching element Q5 is connected in parallel to the secondary side of the third transformer, turned on or off by the third control signal Gate3, it is preferable to be able to flow a current in both directions, so that the silicon controlled rectification It may be composed of a silicon controlled rectifier (SCR).

In addition, the sixth switching element Q6 is connected between the secondary side of the third transformer 320 and the ground GND, and is turned on or off by the inverted signal of the third control signal Gate3, and the MOS transistor ( Metal Oxide Semiconductor Field Effect Transistors (MOS FETs) or Bipolar Junction Transistors (BJTs). Here, the inverter I3 is for inverting the third control signal Gate3.

The sixth switching element Q6 is turned off while the fifth switching element Q5 is turned on, and the sixth switching element Q6 is turned on while the fifth switching element Q5 is turned off.

Here, the primary side of the first transformer 120, the primary side of the second transformer 220 and the primary side of the third transformer 320 are connected in series, a closed loop is formed, and the first control signal Gate1. The phase of, the phase of the second control signal Gate2 and the phase of the third control signal Gate3 are different from each other.

In another exemplary embodiment, a light emitting diode driving apparatus includes a first transformer 120, a first light emitting diode group 130, a first switching element Q1, a second switching element Q2, and a second transformer 220. ), A second LED group 230, a third switching element Q3, and a fourth switching element Q4.

Of course, the primary side of the first transformer 120 and the primary side of the second transformer 220 are connected in series, a closed loop is formed, and the phase of the first control signal Gate1 and the second control signal Gate2 The phases are different.

In addition, the LED driving apparatus according to another embodiment of the present invention is the first transformer 120, the first LED group 130, the first switching element (Q1), the second switching element (Q2), 2 transformer 220, second LED group 230, third switching element Q3, fourth switching element Q4, third transformer 320, third LED group 330, fifth switching It may be configured to include an element Q5, a sixth switching element Q6, a fourth transformer, a fourth LED group, a seventh switching element, and an eighth switching element.

Of course, the primary side of the first transformer 120, the primary side of the second transformer 220, the primary side of the third transformer 320 and the primary side of the fourth transformer are connected in series, a closed loop is formed, The phase of the first control signal Gate1, the phase of the second control signal Gate2, the phase of the third control signal Gate3 and the phase of the fourth control signal are different from each other.

The LED driving apparatus according to the embodiments of the present invention includes a separate switching element for each LED group, and applies a control signal having a different phase to each switching element, thereby effectively distributing a current provided to the LED. Therefore, visual noise and audio noise can be suppressed.

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 LED driving apparatus according to an embodiment of the present invention.

Description of the Related Art [0002]

120: the first transformer

220: second transformer

320: third transformer

Claims (19)

A first transformer for transforming a voltage input to the primary side and providing the voltage to the secondary side; A first switching element connected in parallel to a secondary side of the first transformer and including a silicon controlled rectifier (SCR) to be turned on or off by a first control signal; A second switching element connected between the secondary side of the first transformer and ground and turned on or off by an inverted signal of the first control signal; A first light emitting diode group having a plurality of light emitting diodes connected in series and connected to a secondary side of the first transformer; A second transformer for transforming a voltage input to the primary side and providing the voltage to the secondary side; A silicon controlled rectifier (SCR) connected in parallel to a secondary side of the second transformer and turned on or off by a second control signal having a phase different from that of the first control signal; A third switching element; A fourth switching element connected between the secondary side of the second transformer and ground and turned on or off by an inverted signal of the second control signal; And A plurality of light emitting diodes connected in series and including a second light emitting diode group connected to a secondary side of the second transformer, The primary side of the first transformer and the primary side of the second transformer is connected in series, the light emitting diode drive device is formed. delete delete The method of claim 1, The second switching device includes a MOS transistor (Metal Oxide Semiconductor Field Effect Transistor; MOS FET). The method of claim 1, The second switching device includes a bipolar junction transistor (BJT). delete The method of claim 1, The fourth switching device includes a MOS transistor (Metal Oxide Semiconductor Field Effect Transistor; MOS FET). The method of claim 1, The fourth switching device includes a bipolar junction transistor (BJT). A first transformer for transforming a voltage input to the primary side and providing the voltage to the secondary side; A first switching element connected in parallel to a secondary side of the first transformer and including a silicon controlled rectifier (SCR) to be turned on or off by a first control signal; A second switching element connected between the secondary side of the first transformer and ground and turned on or off by an inverted signal of the first control signal; A first light emitting diode group having a plurality of light emitting diodes connected in series and connected to a secondary side of the first transformer; A second transformer for transforming a voltage input to the primary side and providing the voltage to the secondary side; A silicon controlled rectifier (SCR) connected in parallel to a secondary side of the second transformer and turned on or off by a second control signal having a phase different from that of the first control signal; A third switching element; A fourth switching element connected between the secondary side of the second transformer and ground and turned on or off by an inverted signal of the second control signal; A second light emitting diode group having a plurality of light emitting diodes connected in series and connected to a secondary side of the second transformer; A third transformer for transforming a voltage input to the primary side and providing the voltage to the secondary side; Silicon controlled rectifying element (Silicon) is connected in parallel to the secondary side of the third transformer, and turned on or off by a third control signal having a phase different from the phase of the first control signal and the phase of the second control signal. A fifth switching element including a controlled rectifier (SCR); A sixth switching element connected between the secondary side of the third transformer and ground and turned on or off by an inverted signal of the third control signal; And A plurality of light emitting diodes connected in series and including a third light emitting diode group connected to a secondary side of the third transformer, The primary side of the first transformer, the primary side of the second transformer and the primary side of the third transformer are connected in series, a light emitting diode driving device is formed. delete delete 10. The method of claim 9, The second switching device includes a MOS transistor (Metal Oxide Semiconductor Field Effect Transistor; MOS FET). 10. The method of claim 9, The second switching device includes a bipolar junction transistor (BJT). delete 10. The method of claim 9, The fourth switching device includes a MOS transistor (Metal Oxide Semiconductor Field Effect Transistor; MOS FET). 10. The method of claim 9, The fourth switching device includes a bipolar junction transistor (BJT). delete 10. The method of claim 9, The sixth switching device includes a MOS transistor (Metal Oxide Semiconductor Field Effect Transistor; MOS FET). 10. The method of claim 9, The sixth switching device includes a bipolar junction transistor (BJT).

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