KR20050000656A - Apparatus and method for driving of lamp - Google Patents

Abstract

PURPOSE: A lamp driving apparatus and a lamp driving method are provided to prevent noises by minimizing interferences caused due to electric fields emitted from lamps. CONSTITUTION: A lamp driving apparatus comprises a plurality of AC converting circuits for converting voltages output from an external source into high voltage AC waveforms; a phase synchronization unit for synchronizing phases of high voltage AC waveforms supplied from the AC converting circuits such that the phases have a first phase; a plurality of phase delay units(1081 to 108m) for delaying the first phase to a second phase different from the first phase; a plurality of first lamps driven by the high voltage AC waveforms having the first phase; and a plurality of second lamps interposed between the first lamps such that the second lamps are operated by the high voltage waveforms having a second phase.

Description

Lamp driving device and driving method {APPARATUS AND METHOD FOR DRIVING OF LAMP}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lamp driving device of a liquid crystal display device, and more particularly, to a driving device and a driving method of a lamp to minimize wave interference caused by electric field emission of a plurality of lamps to prevent wave noise.

In general, liquid crystal displays (hereinafter referred to as "LCDs") have tended to be increasingly wider in application due to features such as light weight, thinness, and low power consumption. According to this trend, LCDs are used for office automation equipment, audio / video equipment, and the like. On the other hand, the LCD is controlled to display the desired image on the screen by adjusting the transmission amount of the light beam according to the image signal applied to the plurality of control switches arranged in a matrix form.

Since the LCD is not a self-luminous display device, a light source such as a back light unit is required.

Halogen Cathode Fluorescent Tubes (hereinafter referred to as "HCFLs") or Cold Cathode Fluorescent Tubes are used as light sources used in the backlight unit. Among the light sources, CCFL is a light source tube using the cold emission (electron emission caused by a strong electric field applied to the surface of the cathode), and is easy to generate low heat, high brightness, long life, and full color. These CCFLs include a light guide type, a direct type type, a reflecting plate type, and the like, and a light source tube suitable for the type of LCD is adopted.

This CCFL is driven by a high-pressure AC waveform. That is, a high-voltage AC waveform for driving the CCFL is obtained by converting the DC power supplied from the DC power supply unit into an AC waveform by the inverter and then boosting it by the transformer.

Specifically, the driving apparatus of the lamp according to the related art receives a plurality of CCFLs (Lamp1 to Lampn) for generating light and a voltage from a voltage source (Vcc) and converts them into AC waveforms as shown in FIG. 1. A plurality of inverters 201 to 20n for driving CCFLs (Lamp1 to Lampn) are provided.

The first electrode terminal of each of the plurality of CCFLs (Lamp1 to Lampn) is connected to each of the plurality of inverters 201 to 20n, and the second electrode terminal is connected to the ground voltage source GND. Each of the plurality of CCFLs (Lamp1 to Lampn) emits light by a high-pressure AC waveform supplied from each of the plurality of inverters 201 to 20n.

Each of the plurality of inverters 201 to 20n receives a voltage from a voltage source Vcc and converts it into an AC waveform, and boosts the converted AC waveform to a high voltage AC waveform for driving a plurality of CCFLs (Lamp1 to Lampn). By supplying each of the plurality of CCFLs (Lamp1 to Lampn), an electric field is generated in the plurality of CCFLs (Lamp1 to Lampn) to generate light.

To this end, each of the plurality of inverters 201 to 20n is an inverter integrated circuit (hereinafter referred to as "IC") that receives a voltage from the voltage source Vcc and converts it into an AC waveform using a switching element. To 2n), transformers 41 to 4n for boosting the AC waveform supplied from the inverter ICs 21 to 2n and supplying them to the CCFLs (Lamp1 to Lampn), and pulse width modulation for controlling the switching of the switching elements (Pulse Width). Modulation (hereinafter referred to as "PWM") controllers 61 to 6n.

Each of the inverter ICs 21 to 2n converts the voltage supplied from the voltage source Vcc into an AC waveform using a switching element switched by the PWM control signal from the PWM controllers 61 to 6n. The AC waveform, which is the output waveform of the inverter ICs 21 to 2n, is supplied to the transformers 41 to 4n.

Each of the transformers 41 to 4n boosts the AC waveform supplied from the inverter ICs 21 to 2n to a high voltage AC waveform for driving the CCFLs Lamp1 to Lampn. For this purpose, the primary windings of the transformers 41 to 4n are connected to the inverter ICs 21 to 2n, and the secondary windings are connected to the first electrode terminals of the CCFLs (Lamp1 to Lampn).

Each of the PWM controllers 61 to 6n receives feedback of a luminance control signal (not shown) or a tube current flowing through the CCFLs (Lamp1 to Lampn) to control the switching of the switching elements of the inverter ICs 21 to 2n.

Such a lamp driving apparatus according to the prior art drives a plurality of CCFLs (Lamp1 to Lampn) by a high-pressure AC waveform supplied from the transformers 41 to 4n to the plurality of CCFLs (Lamp1 to Lampn). That is, each of the plurality of CCFLs (Lamp1 to Lampn) is driven by a high-pressure AC waveform supplied from different transformers 41 to 4n. Accordingly, the high-voltage AC waveforms supplied to each of the plurality of CCFLs (Lamp1 to Lampn) have different phases (X, X ', Y, Y', Z, Z ') as shown in FIGS. Can have In other words, the phases of the high-pressure AC waveform supplied from the transformers 41 to 4n are different for each of the positions of the plurality of CCFLs (Lamp1 to Lampn). Therefore, the shape of the electric field emitted from each of the CCFLs (Lamp1 to Lampn) is different for each position of the plurality of CCFLs (Lamp1 to Lampn). Therefore, the driving apparatus of the lamp according to the prior art has a different amount of emission or shape of the electric field for each position of a plurality of CCFLs (Lamp1 to Lampn), so that a wave noise phenomenon occurs.

Accordingly, it is an object of the present invention to provide a driving apparatus and a driving method of a lamp to minimize the interference caused by the electric field emission of a plurality of lamps to prevent wave noise phenomenon.

1 is a block diagram showing a driving device of a general lamp.

2 and 3 are waveform diagrams showing the electric field superimposition emitted when driving a plurality of CCFLs shown in FIG.

Figure 4 is a block diagram showing a driving device of the lamp according to an embodiment of the present invention.

FIG. 5 is a waveform diagram showing a phase difference of a high-voltage AC waveform supplied to each of the plurality of CCFLs shown in FIG. 4. FIG.

FIG. 6 is a waveform diagram illustrating superposition of electric fields emitted when driving a plurality of CCFLs shown in FIG. 4. FIG.

7 is a block diagram showing a driving device for a lamp according to another embodiment of the present invention.

FIG. 8 is a waveform diagram showing a phase difference of a high-voltage AC waveform supplied to each of the plurality of CCFLs shown in FIG. 4.

<Description of Symbols for Main Parts of Drawings>

21 to 2n, 102: inverter IC 41 to 4n, 104: transformer

61 to 6n, 106: PWM controller 201 to 20n, 120: inverter

108: phase retarder

In order to achieve the above object, the driving device of the lamp according to an embodiment of the present invention is a plurality of AC conversion circuit for converting a voltage supplied from the outside into a high-voltage AC waveform, and the plurality of AC conversion circuit is supplied from each A phase synchronizer for synchronizing phases of the high-voltage AC waveforms with each other to have a first phase, a plurality of phase retarders for delaying the first phase to a second phase different from the first phase, and having the first phase And a plurality of first lamps driven by the high-voltage alternating current waveform, and a plurality of second lamps disposed between the plurality of first lamps and driven by the high-pressure alternating current waveform having the second phase. Characterized in that.

In the driving device of the lamp, the first phase and the second phase are characterized by having a phase difference of 90 degrees.

In the driving device of the lamp, the first phase and the second phase are characterized by having a phase difference of 270 degrees.

In the driving device of the lamp, each of the plurality of AC conversion circuits uses a switching element to convert a voltage supplied from the outside into an AC waveform, and converts the AC waveform from the switching circuit into the AC voltage of the high voltage. And a switching controller for controlling the switching of the switch element.

According to an embodiment of the present invention, a method of driving a lamp may include converting a voltage supplied from an external source into a high-voltage AC waveform, and synchronizing each phase of the high-voltage AC waveform with a first phase by using a phase synchronizer. Delaying the first phase to a second phase different from the first phase by using a phase retarder, and supplying the high voltage AC waveform having the first phase to a plurality of first lamps. Driving the plurality of second lamps by driving the plurality of first lamps and simultaneously supplying the high voltage AC waveform having the second phase to the plurality of second lamps disposed between the plurality of first lamps. It characterized in that it comprises a step of.

In the driving method of the lamp, the first phase and the second phase are characterized in that the phase difference of 90 degrees.

In the driving method of the lamp, the first phase and the second phase are characterized in that they have a phase difference of 270 degrees.

In the method of driving the lamp, the step of converting the voltage supplied from the outside into a high voltage AC waveform includes converting a voltage supplied from the outside into an AC waveform using a switch element of a switching circuit, and using the transformer using the AC And converting a waveform into the high voltage alternating current waveform, and controlling the switching of the switch element using a switching controller.

Other objects and features of the present invention in addition to the above object will be apparent from the description of the embodiments with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described with reference to FIGS. 4 to 8.

Referring to FIG. 4, a driving apparatus for a lamp according to an exemplary embodiment of the present invention receives a plurality of CCFLs (Lamp1 to Lampn) for generating light and voltages from a voltage source (Vcc) and converts them into high-voltage AC waveforms. A plurality of inverters 1201 to 120n for driving CCFLs (Lamp1 to Lampn) and a high voltage AC waveform supplied from each of the plurality of inverters 1201 to 120n are synchronized to each of the plurality of CCFLs (Lamp1 to Lampn). A plurality of phase delay units 130 for supplying and a plurality of phase delay units for delaying the phase of the high-voltage AC waveform supplied to the even-numbered CCFLs (Lamp2, Lamp4 to Lampn) among the output terminals of the phase synchronizer 130 by 90 degrees. Phase retarders 1081 to 108m (wherein m is n / 2).

The first electrode terminal of each of the plurality of CCFLs (Lamp1 to Lampn) is connected to each of the plurality of inverters 1201 to 120n, and the second electrode terminal is connected to the ground voltage source GND. Each of the plurality of CCFLs (Lamp1 to Lampn) emits light by a high-pressure AC waveform supplied from each of the plurality of inverters 1201 to 120n. In this case, the high-frequency AC waveform having the first phase is supplied to the odd-numbered CCFLs (Lamp1, Lamp3 to Lampn-1) of the plurality of CCFLs (Lamp1 to Lampn), and the plurality of CCFLs (Lamp1 to Lampn). Among the even-numbered CCFLs (Lamp2, Lamp4 to Lampn), the AC waveform of the high voltage having the second phase having a phase difference of 90 degrees with the first phase is supplied.

Each of the plurality of inverters 1201 to 120n receives a voltage from a voltage source Vcc and converts it into an AC waveform, and boosts the converted AC waveform to a high voltage AC waveform for driving a plurality of CCFLs (Lamp1 to Lampn). By supplying each of the plurality of CCFLs (Lamp1 to Lampn), an electric field is generated in the plurality of CCFLs (Lamp1 to Lampn) to generate light.

To this end, each of the plurality of inverters 1201 to 120n is an inverter integrated circuit (hereinafter referred to as "IC") 1021 that receives a voltage from the voltage source Vcc and converts it into an AC waveform using a switching element. To 102n), transformers 1041 to 104n for boosting the AC waveform supplied from the inverter ICs 1021 to 102n and supplying them to the CCFLs (Lamp1 to Lampn), and pulse width modulation for controlling the switching of the switching elements. Modulation (hereinafter referred to as " PWM ") controllers 1061 to 106n.

Each of the inverter ICs 1021 to 102n converts the voltage supplied from the voltage source Vcc into an AC waveform by using a switching element switched by the PWM control signal from the PWM controllers 1061 to 106n. The AC waveform, which is the output waveform of the inverter ICs 1021 to 102n, is supplied to the transformers 1041 to 104n.

Each of the transformers 1041 to 104n boosts the AC waveform supplied from the inverter ICs 1021 to 102n to a high voltage AC waveform for driving the CCFLs (Lamp1 to Lampn). To this end, the primary winding of each of the transformers 1041 to 104n is connected to the inverter ICs 1021 to 102n, and the secondary winding is connected to the phase synchronizer 130.

Each of the PWM controllers 1061 to 106n receives feedback from a luminance control signal (not shown) or a tube current flowing through the CCFLs (Lamp1 to Lampn) to control switching of the switching elements of the inverter ICs 1021 to 102n.

The phase synchronizer 130 is connected to a plurality of input terminals connected to output lines of each of the transformers 1041 to 104n and to first electrode terminals of each of a plurality of CCFLs (Lamp1 to Lampn). The phase synchronizer 130 synchronizes the phases of the high-voltage AC waveforms supplied from the output lines of the transformers 1041 to 104n to be supplied to the first electrode terminals of each of the plurality of CCFLs (Lamp1 to Lampn). do.

Each of the plurality of phase delayers 1801 to 108m has an even second (2n) output terminal among the output terminals of the phase synchronizer 130 and the even second CCFL (Lamp2, Lamp4 to Lampn) among the plurality of CCFLs (Lamp1 to Lampn). It is connected between each 1st electrode terminal. Each of the plurality of phase retarders 1801 to 108n delays the phase of the high-voltage AC waveform output through the even-numbered output terminal of the phase synchronizer 130 by 90 degrees. The 90-degree (Sin (wt + π / 2rad)) delayed high-voltage AC waveforms output from each of the plurality of phase retarders 1081 to 108m are the even-numbered CCFLs (Lamp2 and Lamp4) among the plurality of CCFLs (Lamp1 to Lampn). To Lampn).

As described above, the driving device and the driving method of the lamp according to the embodiment of the present invention synchronize the phases of the high-voltage AC waveforms supplied from each of the plurality of inverters 1201 to 120n by using the synchronous phase unit 130. As shown in FIG. 5, the high-frequency AC waveforms synchronized with each other are supplied to the odd-numbered CCFLs (Lamp1, Lamp3 to Lampn-1) among the plurality of CCFLs (Lamp1 to Lampn), and the plurality of phase delays 1081 to 108 m) is used to delay the phase of the high-voltage AC waveform output from the phase synchronizer 130 by 90 degrees (Sin (wt + Π / 2rad)) to obtain the even-numbered CCFL (Lamp2, Lamp4) among the plurality of CCFLs (Lamp1 to Lampn). In this way, a high-voltage alternating current waveform and a superior CCFL (Lamp2, Lamp4 to Lampn) supplied to the odd-numbered CCFLs (Lamp1, Lamp3 to Lampn-1) among the plurality of CCFLs (Lamp1 to Lampn) are supplied. Are shown in FIG. 6. By having a 90-degree phase difference (X, Y) as described above, it is possible to minimize the overlap of the electric field emitted when driving the plurality of CCFL (Lamp1 to Lampn), thus, the electric field emitted when driving a plurality of CCFL (Lamp1 to Lampn) Minimize wave noise caused by overlapping

Meanwhile, in the driving apparatus and the driving method of the lamp according to another embodiment of the present invention, each of the plurality of phase retarders 1081 to 108n is an odd number among the output terminals of the phase synchronizer 130 as shown in FIG. 7. It is connected between the output terminal and the odd CCFLs (Lamp1, Lamp3 to Lampn-1) of the plurality of CCFLs (Lamp1 to Lampn), and the high voltage output from the odd output terminal among the output terminals of the phase synchronizer 130. The phase of the AC waveform is delayed by 90 degrees and is supplied to each of the odd CCFLs (Lamp1, Lamp3 to Lampn-1) among the plurality of CCFLs (Lamp1 to Lampn).

As such, the high-voltage alternating current waveform supplied to the even-numbered CCFLs (Lamp2, Lamp4 to Lampn) among the plurality of CCFLs (Lamp1 to Lampn) and the high-pressure alternating current supplied to the odd-numbered CCFLs (Lamp1, Lamp3 to Lampn-1) Since the waveform has a phase difference of 90 degrees, it is possible to minimize the superposition of the electric field emitted when driving the plurality of CCFLs (Lamp1 to Lampn). Accordingly, wave noise due to superposition of electric fields emitted when a plurality of CCFLs (Lamp1 to Lampn) are driven may be minimized.

On the other hand, in the driving device and driving method of the lamp according to another embodiment of the present invention, each of the plurality of phase retarders 1081 to 108m is a high voltage output from the phase synchronizer 130 as shown in FIG. The phase of the AC waveform is delayed by 270 degrees and supplied to the even-numbered CCFLs (Lamp2, Lamp4 to Lampn) of the plurality of CCFLs (Lamp1 to Lampn). Accordingly, the high-voltage AC waveform output from the phase synchronizer 130 is supplied to the odd CCFLs Lamp1 and Lamp3 to Lampn-1 among the plurality of CCFLs Lamp1 to Lampn, and the plurality of phase delays 1081 to AC waveform of high voltage delayed by 270 degrees by 108m) is supplied to the odd CCFLs (Lamp1, Lamp3 to Lampn-1).

As such, the high-voltage AC waveforms supplied to the odd-numbered CCFLs (Lamp1, Lamp3 to Lampn-1) among the plurality of CCFLs (Lamp1 to Lampn) and the high-pressure alternating current supplied to the even-numbered CCFLs (Lamp2, Lamp4 to Lampn) Since the waveform has a phase difference of 270 degrees, it is possible to minimize the overlap of the electric field emitted when driving the plurality of CCFLs (Lamp1 to Lampn). Accordingly, wave noise due to superposition of electric fields emitted when a plurality of CCFLs (Lamp1 to Lampn) are driven may be minimized.

Also, in the lamp driving apparatus and the driving method according to another embodiment of the present invention, each of the plurality of phase retarders 1081 to 108m delays the phase of the high-voltage AC waveform output from the phase synchronizer 130 by 270 degrees. The first CCFLs (Lamp1, Lamp3 to Lampn-1) of the plurality of CCFLs (Lamp1 to Lampn) are supplied. Accordingly, the high-voltage AC waveform output from the phase synchronizer 130 is supplied to the even-numbered CCFLs (Lamp2, Lamp4 to Lampn) of the plurality of CCFLs (Lamp1 to Lampn), and the plurality of phase delays (1081 to 108m). Is supplied to the high-frequency AC waveform base CCFLs (Lamp1, Lamp3 to Lampn-1) delayed by 270 degrees.

As such, the high-voltage alternating current waveform supplied to the even-numbered CCFLs (Lamp2, Lamp4 to Lampn) among the plurality of CCFLs (Lamp1 to Lampn) and the high-pressure alternating current supplied to the odd-numbered CCFLs (Lamp1, Lamp3 to Lampn-1) Since the waveform has a phase difference of 270 degrees, the superposition of the electric field emitted when driving the plurality of CCFLs (Lamp1 to Lampn) can be minimized. Thus, the wave due to the superposition of the electric field emitted when the multiple CCFLs (Lamp1 to Lampn) is driven. Noise can be minimized.

As described above, the driving device and the driving method of the lamp according to the embodiment of the present invention by using a phase synchronizer to synchronize the high-voltage AC waveform supplied from the plurality of inverters to the first phase, using a plurality of phase delays Delaying the first phase by 90 degrees or 270 degrees to generate a high-pressure alternating current waveform having a second phase, and supplying a high-pressure alternating current waveform having a first phase to the odd-numbered lamps among the plurality of lamps; The high-pressure AC waveform having a is supplied to the even lamps. Accordingly, in the present invention, since the high-voltage AC waveforms supplied to each of the adjacent lamps have a phase difference of 90 degrees or 270 degrees, it is possible to minimize wave overlap by minimizing the overlap of electric fields emitted when driving a plurality of lamps.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (8)

A plurality of AC conversion circuits for converting an externally supplied voltage into a high-voltage AC waveform, A phase synchronizer for synchronizing the phases of the high-voltage AC waveforms supplied from each of the plurality of AC conversion circuits with each other to have a first phase; A plurality of phase retarders for delaying the first phase to a second phase different from the first phase, A plurality of first lamps driven by the high voltage alternating current waveform having the first phase, And a plurality of second lamps disposed between the plurality of first lamps and driven by the high voltage alternating current waveform having the second phase. The method of claim 1, And the first phase and the second phase have a 90 degree phase difference. The method of claim 1, And the first phase and the second phase have a phase difference of 270 degrees. The method of claim 1, Each of the plurality of AC conversion circuits, A switching circuit for converting a voltage supplied from the outside into an AC waveform using a switch element, A transformer for converting the alternating current waveform from the switching circuit into the high voltage alternating current waveform; And a switching controller for controlling the switching of the switch element. Converting a voltage supplied from the outside into a high voltage AC waveform, Synchronizing phases of the high-voltage AC waveforms with each other to have a first phase by using a phase synchronizer; Delaying the first phase to a second phase different from the first phase using a phase retarder, The high voltage AC waveform having the second phase is supplied to the plurality of first lamps by supplying the high voltage AC waveform having the first phase to the plurality of first lamps while driving the plurality of first lamps. And driving the plurality of second lamps by supplying a plurality of second lamps disposed between the plurality of lamps. The method of claim 5, wherein And the first phase and the second phase have a 90 degree phase difference. The method of claim 5, wherein And the first phase and the second phase have a 270 degree phase difference. The method of claim 5, wherein The step of converting the voltage supplied from the outside into a high voltage AC waveform, Converting a voltage supplied from the outside into an AC waveform using a switch element of a switching circuit, Converting the AC waveform to the high voltage AC waveform using a transformer; And controlling the switching of the switch element by using a switching control unit.