KR20100138634A - Apparatus for driving light emitting diode - Google Patents

Abstract

PURPOSE: A light emitting diode driving device is provided to equally control a current applied to a light emitting diode by comprising a current mirror as a PNP bipolar junction transistor or PMOS transistor. CONSTITUTION: A plurality of light emitting diodes are serially connected to a first light emitting diode group(1120). A first current provider(1110) provides a current to a first light emitting diode group. A plurality of light emitting diodes are serially connected to a second light emitting diode group(1220). A second current provider(1210) provides a current to the second light emitting diode group. A third current provider(1310) provides a current to a third light emitting diode group(1320).

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, there is a problem in that the currents provided to each of the light emitting diodes cannot be controlled identically.

The LED driving apparatus according to the embodiment can equally control the current provided to each of the LEDs.

In one embodiment, a LED driving apparatus includes a first LED group to which a plurality of LEDs are connected in series, a first current providing unit to supply current to the first LED group, and a plurality of LEDs to be connected in series A second light emitting diode group and a second current providing unit for supplying the same current as the first current providing unit to the second light emitting diode group.

In another embodiment, a light emitting diode driving apparatus includes a first light emitting diode group to which a plurality of light emitting diodes are connected in series, a first current providing unit to supply current to the first light emitting diode group, and a plurality of light emitting diodes to be connected in series. A second light emitting diode group, a second current providing unit providing the same current as the first current providing unit to the second light emitting diode group, a third light emitting diode group in which a plurality of light emitting diodes are connected in series, and the first current providing unit And a third current providing unit configured to provide a current equal to the third LED group.

In the LED driving apparatus according to the exemplary embodiment, a current mirror circuit may be configured of a PNP bipolar junction transistor or a PMOS transistor, thereby controlling the current provided to each LED.

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.

In the LED driving apparatus according to the exemplary embodiment of the present invention, as shown in FIG. 1, the first LED group 1120, the first current providing unit 1110, the first current sensing unit 1130, and the second emission Diode group 1220, second current providing unit 1210, second current sensing unit 1230, third LED group 1320, third current providing unit 1310 and third current sensing unit 1330 It may be configured to include.

The first LED group 1120 is connected to a plurality of LEDs in series, the first current providing unit 1110 provides a current to the first LED group 1120, and the first current sensing unit 1130. Senses a current flowing in the first LED group 1120, and specifically, may be configured as a resistor R1.

In the second LED group 1220, a plurality of LEDs are connected in series, and the second current providing unit 1210 transmits the same current as the first current providing unit 1110 to the second LED group 1220. In addition, the second current sensing unit 1230 senses a current flowing in the second LED group 1220, and specifically, may include a resistor R2.

In the third LED group 1320, a plurality of LEDs are connected in series, and the third current providing unit 1310 transmits the same current as the first current providing unit 1110 to the third LED group 1320. The third current sensing unit 1330 may sense a current flowing in the third LED group 1320, and specifically, may include a resistor R3.

Here, the first current providing unit 1110 may include a first PNP bipolar junction transistor in which an emitter is connected to a power supply voltage, a base and a collector are connected, and a collector is connected to the first LED group 1120. And a second current providing unit 1210 having an emitter connected to a power supply voltage, a base connected to a base of the first PNP bipolar junction transistor Q1, and a collector connected to the second light emitting diode. And a second PNP bipolar junction transistor Q2 connected to the group 1220, wherein the third current providing unit 1310 includes an emitter connected to a power supply voltage and a base connected to the first PNP bipolar junction transistor Q1. And a third PNP bipolar junction transistor Q3 coupled to the base of the collector and coupled to the third LED group 1320.

The LED driving apparatus according to an exemplary embodiment of the present invention includes a current mirror as a first PNP bipolar junction transistor Q1, a second PNP bipolar junction transistor Q2, and a third PNP bipolar junction transistor Q3. mirror), the magnitude of the impedance of the load connected to the first current providing unit 1110, the magnitude of the impedance of the load connected to the second current providing unit 1210 and the third current providing unit 1310. The first current providing unit 1110, the second current providing unit 1210, and the third current providing unit 1310 may provide the same current regardless of the magnitude of the impedance of the load to be connected.

The LED driving apparatus according to an embodiment of the present invention includes a first current providing unit 1110, a first LED group 1120, a first current sensing unit 1130, a second current providing unit 1210, and a second current providing unit 1120. The second LED group 1220 and the second current sensing unit 1230 may be configured to include the first current providing unit 1110, the first LED group 1120, and the first current sensing unit 1130. ), The second current providing unit 1210, the second light emitting diode group 1220, the second current sensing unit 1230, the third current providing unit 1310, the third light emitting diode group 1320, and the third current The sensing unit 1330, the fourth current providing unit, the fourth LED group, and the fourth current sensing unit may also be configured.

Here, the fourth current providing unit includes a fourth PNP bipolar junction transistor having an emitter connected to a power supply voltage, a base connected to a base of the first PNP bipolar junction transistor Q1, and a collector connected to a fourth LED group. It includes.

A light emitting diode driving apparatus according to another embodiment of the present invention will be described with reference to FIG.

Here, the first current providing unit 2110 includes a first PMOS transistor having a source connected to a power supply voltage, a gate and a drain connected, and a drain connected to the first LED group 2120. And a second current providing part 2210 having a source connected to a power supply voltage, a gate connected to a gate of the first PMOS transistor M1, and a drain connected to the second LED group 2220. And a second PMOS transistor M2 connected to the third current providing unit 2310, a source of which is connected to a power supply voltage, a gate of which is connected to a gate of the first PMOS transistor M1, and a drain of the third PMOS transistor M2. The third PMOS transistor M3 is connected to the LED group 2320.

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.

2 is a circuit diagram of a LED driving apparatus according to another embodiment of the present invention.

<Description of Signs of Major Parts of Drawings>

1110: first current providing unit 1120: first light emitting diode group

1210: second current providing unit 1220: second LED group

1310: third current providing unit 1320: third LED group

Claims (16)

A first light emitting diode group in which a plurality of light emitting diodes are connected in series; A first current providing unit providing a current to the first LED group; A second light emitting diode group in which a plurality of light emitting diodes are connected in series; And And a second current providing unit configured to supply the same current to the second LED group as the first current providing unit. The method of claim 1, The first current providing unit includes a first PNP bipolar junction transistor having an emitter connected to a power supply voltage, a base and a collector connected, and the collector connected to the first LED group, and the second current providing unit And a second PNP bipolar junction transistor having an emitter connected to the power supply voltage, a base connected to a base of the first PNP bipolar junction transistor, and a collector connected to the second LED group. The method of claim 1, The first current providing unit includes a first PMOS transistor having a source connected to a power supply voltage, a gate and a drain connected, and the drain connected to the first LED group, and the second current providing unit having a source connected to the power supply. And a second PMOS transistor connected to a voltage, a gate connected to a gate of the first PMOS transistor, and a drain connected to the second LED group. The method of claim 1, And a first current sensing unit configured to sense a current flowing through the first LED group. The method of claim 4, wherein The first current sensing unit includes a resistor. The method of claim 1, And a second current sensing unit configured to sense a current flowing through the second LED group. The method of claim 6, The second current sensing unit includes a resistor. A first light emitting diode group in which a plurality of light emitting diodes are connected in series; A first current providing unit providing a current to the first LED group; A second light emitting diode group in which a plurality of light emitting diodes are connected in series; A second current providing unit configured to provide a current equal to the first current providing unit to the second LED group; A third light emitting diode group in which a plurality of light emitting diodes are connected in series; And And a third current providing unit configured to supply the same current to the third LED group as the first current providing unit. The method of claim 8, The first current providing unit includes a first PNP bipolar junction transistor having an emitter connected to a power supply voltage, a base and a collector connected, and the collector connected to the first LED group, and the second current providing unit A second PNP bipolar junction transistor having an emitter connected to the power supply voltage, a base connected to a base of the first PNP bipolar junction transistor, and a collector connected to the second LED group, wherein the third current The providing part includes a third PNP bipolar junction transistor having an emitter connected to the power supply voltage, a base connected to a base of the first PNP bipolar junction transistor, and a collector connected to the third LED group. Device. The method of claim 8, The first current providing unit includes a first PMOS transistor having a source connected to a power supply voltage, a gate and a drain connected, and the drain connected to the first LED group, and the second current providing unit having a source connected to the power supply. A second PMOS transistor connected to a voltage, a gate connected to a gate of the first MOS transistor, and a drain connected to the second LED group, wherein the third current providing unit is connected to a source voltage And a third PMOS transistor having a gate connected to the gate of the first PMOS transistor and a drain connected to the third LED group. The method of claim 8, And a first current sensing unit configured to sense a current flowing through the first LED group. The method of claim 11, The first current sensing unit includes a resistor. The method of claim 8, And a second current sensing unit configured to sense a current flowing through the second LED group. The method of claim 13, The second current sensing unit includes a resistor. The method of claim 8, And a third current sensing unit configured to sense a current flowing through the third LED group. The method of claim 15, The third current sensing unit includes a resistor.

Images