KR20100058157A - Inverter circuit for liquid crystal display backlight - Google Patents

Abstract

PURPOSE: An inverter circuit for an LCD backlight is provided to control an output current of a lamp by supplying a driving pulse corresponding to a compensation current to an output current deviation controller. CONSTITUTION: First and second transformers(102,104) comprise a first winding and a second winding. An output current deviation controller(106) is electrically connected to the output terminal of the first and second transformers. The output current deviation controller controls the output current of the lamp by comparing the output signals of the first and second transformers. A driving pulse supply unit(108) is electrically connected to the first winding of the first and second transformers and the output current deviation controller. The driving pulse supply unit supplies the driving pulse corresponding to the compensation current to the output current deviation controller.

Description

Inverter circuit for liquid crystal display backlight

An embodiment relates to an inverter circuit for an LCD backlight.

In general, an LCD backlight inverter circuit converts an input DC voltage into an AC voltage to turn on a backlight of a liquid crystal display, and boosts the converted AC voltage to several hundred volts to supply an appropriate driving power for the backlight.

At this time, the LCD backlight inverter circuit used a transformer having two outputs as two inputs.

In the conventional LCD backlight inverter circuit, there is a problem that a deviation of the output current occurs when driving the lamp.

Therefore, in recent years, an improved inverter circuit for LCD backlight that can eliminate variations in output current when driving a lamp has been continuously studied.

The LCD backlight inverter circuit according to the embodiment can eliminate the variation of the output current when driving the lamp.

An inverter backlight circuit for an LCD according to an embodiment is electrically connected to a first transformer and a second transformer for driving lamps including a primary winding and a secondary winding, and an output terminal of the first transformer and the second transformer. And an output current deviation control unit for comparing the output signals of the first transformer and the second transformer with each other and equally supplying the output current to the lamps, and the first winding of the first transformer and the second transformer. It is electrically connected to the primary winding and the output current deviation controller, respectively, to supply the converted AC voltage to the first transformer and the second transformer, respectively, and to output the compensation current to the compensation current to the output current deviation controller. And a driving pulse supply unit for supplying a corresponding driving pulse.

The LCD backlight inverter circuit according to the embodiment has the effect of eliminating the deviation of the output current when driving the lamp.

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

<Examples>

1 is a view showing an inverter circuit for an LCD backlight according to an embodiment of the present invention.

Referring to FIG. 1, the inverter backlight circuit 100 for an LCD backlight according to an embodiment of the present invention may include a first transformer 102, a second transformer 104, an output current deviation controller 106, and a driving pulse. Supply unit 108 and the like.

The first and second transformers 102 and 104 are provided to drive the lamps 101 including a first secondary winding and a second secondary winding.

Here, the primary winding may be an input winding and the secondary winding may be an output winding.

At this time, the lamps 101 may be at least one of a Cold Cathode Fluorescent Lamp (CCFL) or an Exterior Electrode Fluorescent Lamp (EEFL).

The output current deviation adjusting unit 106 is electrically connected to the output terminals of the first transformer 102 and the second transformer 104, and output signals of the first transformer 102 and the second transformer 104. Are compared to each other and provided to match the output current to the lamps 101 equally.

In this case, the output current deviation adjusting unit 106 may include a first output current deviation adjusting unit 106a and a second output current deviation adjusting unit 106b.

In more detail, the first output current deviation adjusting unit 106a may include a first comparator 106a1, a first switching element TR1, a first smoothing capacitor C1, and the like.

The first comparator 106a1 may be electrically connected to the output terminal of the first transformer 102 and include at least one terminal.

That is, at least one terminal may be a negative terminal and a grounded positive terminal.

In this case, the first comparator 106a1 may be a first inverting OP-AMP.

The first switching element TR1 may be electrically connected to the output terminal of the first comparator 106a1, and may be provided so that one end thereof is grounded. The first smoothing capacitor C1 may include the other end and the first end of the first switching element TR1. 1 may be provided to be electrically connected to the output terminal of the transformer 102 and the lamps 101.

In addition, the second output current deviation adjusting unit 106b may include a second comparator 106b1, a second switching element TR1, a second smoothing capacitor C2, and the like.

The second comparator 106b1 may be electrically connected to the output terminal of the second transformer 104, electrically connected in parallel with the first comparator 106a1, and may include at least one terminal.

That is, at least one terminal may be a negative terminal and a grounded positive terminal.

In this case, the second comparator 106b1 may be a second inverting OP-AMP.

The second switching element TR2 is electrically connected to the output terminal of the second comparator 106b1, and may be provided so that one end thereof is grounded, and the second smoothing capacitor C2 is formed on the other end of the second switching element TR2 and the second switching element TR2. 2 may be electrically connected to the output terminal of the transformer 104 and the lamps 101.

In this case, the first switching element TR1 and the second switching element TR2 may be at least one of a bipolar junction transistor (BJT) and a metal-oxide semiconductor field effect transistor (MOSFET).

The driving pulse supply 108 is electrically connected to the first primary winding of the first transformer 102 and the first secondary winding of the second transformer 104 and the output current deviation adjuster 106, respectively, so that the first transformer It may be provided to supply the converted AC voltage to the transformer 102 and the second transformer 104, respectively.

In addition, the driving pulse supply unit 108 may be provided to supply a driving pulse corresponding to the compensation current to the output current deviation control unit 106 to drive the lamps 101 constantly.

In this case, the driving pulse supply unit 108 may include a DC-AC converter 108a and a compensation current supply unit 108b.

That is, the DC-AC converter 108a may be provided to convert the DC voltage into the AC voltage and supply the first transformer 102 and the second transformer 104, and the compensation current supply means 108b is output. The current deviation adjusting unit 106 may be provided to supply a driving pulse corresponding to the compensation current.

As described above, the operating state of the LCD backlight inverter circuit 100 according to an embodiment of the present invention will be described.

First, the output currents Io (M) and Io (S) output by being boosted by the first and second transformers 102 and 104 by receiving the AC voltage converted by the driving pulse supply unit 108 are first. And 2 output current deviation adjusting units 106a and 106b.

At this time, the first and second comparators 106a1 and 106b1 compare the amounts of the output currents Io (M) and Io (S) with the reference output currents, and compare the amounts of the first and second switching elements TR1 and TR2. By selectively turning on operation, the compensation current supplied from the compensation current supply means 108b is stored in the first and second smoothing capacitors C1 and C2 so that the same output current can be supplied to the lamps 101. do.

Therefore, the LCD backlight inverter circuit 100 according to an embodiment of the present invention can eliminate the variation of the output current when driving the lamp.

Those skilled in the art to which the present invention pertains will understand that the present invention can be implemented in other specific forms without changing the technical spirit or essential features. Therefore, it should be understood that the above-described embodiments are to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than the foregoing description, It is intended that all changes and modifications derived from the equivalent concept be included within the scope of the present invention.

1 is a view showing an inverter circuit for an LCD backlight according to an embodiment of the present invention.

Description of the main parts of the drawing

100 inverter circuit for LCD backlight 102 first transformer

104: second transformer 106: output current deviation adjusting unit

106a: first output current deviation adjusting unit 106a1: first comparator

106b: second output current deviation adjusting unit 106b1: second comparator

108: driving pulse supply unit 108a: DC-AC converter

108b: compensation current supply means

Claims (6)

A first transformer and a second transformer for driving lamps including a primary winding and a secondary winding; An output electrically connected to an output terminal of the first transformer and the second transformer, and comparing output signals of the first transformer and the second transformer with each other to equally supply an output current to the lamps Current deviation control unit; And AC voltage converted to the first transformer and the second transformer by being electrically connected to the primary winding of the first transformer, the primary winding of the second transformer, and the output current deviation adjusting unit, respectively. And a driving pulse supply unit supplying driving pulses corresponding to a compensation current to the output current deviation adjusting unit to supply the respective lamps and driving the lamps constantly. The method of claim 1, The output current deviation adjusting unit, A first comparator electrically connected to an output terminal of the first transformer and including at least one terminal; A first switching element electrically connected to an output terminal of the first comparator and having one end grounded; A first smoothing capacitor electrically connected to the other end of the first switching element, the output end of the first transformer, and the lamps; A second comparator electrically connected to an output terminal of the second transformer and electrically connected in parallel with the first comparator, and including at least one; A second switching element electrically connected to an output terminal of the second comparator and having one end grounded; And And a second smoothing capacitor electrically connected to the other end of the second switching element, the output end of the second transformer, and the lamps. 3. The method of claim 2, And the first comparator and the second comparator include a first inverting OP-AMP and a second inverting OP-AMP. 3. The method of claim 2, And the first switching element and the second switching element include at least one of a bipolar junction transistor (BJT) and a metal-oxide semiconductor field effect transistor (MOSFET). The method of claim 1, The driving pulse supply unit, A DC-AC converter converting a DC voltage into an AC voltage and supplying the first transformer and the second transformer; And And a compensation current supply means for supplying a driving pulse corresponding to the compensation current to the output current deviation control unit. The method of claim 1, And the lamps include at least one of a Cold Cathode Fluorescent Lamp (CCFL) or an Exterior Electrode Fluorescent Lamp (EEFL).

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