KR101107689B1 - Driving apparatus and method for lamp of liquid crystal display - Google Patents

Abstract

The present invention relates to a lamp driving device and a method of a liquid crystal display device capable of detecting a lamp failure by detecting an induced voltage of the lamp. The lamp driving device of the liquid crystal display device according to the present invention comprises a first electrode and a second electrode. A plurality of lamps having a plurality of lamps, a first inverter for commonly supplying an AC waveform having a high voltage having a first phase to the first electrode, and a high voltage having a second phase different from the first phase to the second electrode A second inverter for commonly supplying an AC waveform of a plurality of conductors, a plurality of conductors directly wound around a glass tube outer periphery of each lamp so as to be as close as possible to the first electrode, and detecting an induced voltage induced in the respective lamps A logic line that is connected to the plurality of conductors through a signal line and logically calculates a feedback signal corresponding to the induced voltage supplied from the plurality of conductors. And a shut-off gate, a comparator for comparing a result of the logic operation with a reference voltage, a shutdown signal generator for generating a shutdown signal, and controlling the first and second inverters, and according to the shutdown signal. And a control unit for shutting down the first and second inverters.

According to this configuration, the present invention operates only at the time of abnormality of the lamps regardless of the initial lighting voltage of all the lamps, and can improve the reliability of the liquid crystal display by shutting down the inverter even when at least one lamp is abnormally operated.

Description

Lamp driving device and method of liquid crystal display device {DRIVING APPARATUS AND METHOD FOR LAMP OF LIQUID CRYSTAL DISPLAY}

1 is a view showing a lamp driving device of a general liquid crystal display.

2 is a diagram illustrating a lamp driving device of a liquid crystal display according to an exemplary embodiment of the present invention.

3 is a schematic view of a liquid crystal display according to an exemplary embodiment of the present invention.

4 is a diagram illustrating a shutdown signal generator of the first embodiment shown in FIG. 2.

FIG. 5 is a diagram illustrating a shutdown signal generator of the second embodiment shown in FIG. 2. FIG.

FIG. 6 is a diagram illustrating a shutdown signal generator of the third embodiment shown in FIG. 2. FIG.

FIG. 7 is a diagram illustrating a shutdown signal generator of the fourth embodiment shown in FIG. 2. FIG.

FIG. 8 shows another type of conductor shown in FIG. 2; FIG.

FIG. 9 shows another type of conductor shown in FIG. 2; FIG.

<Explanation of Signs of Major Parts of Drawings>

10a to 10n, 110a to 110n: lamp 20, 120, 130: inverter

22a to 22n, 122, 132: transformer 28: detector

24a to 24m, 124, 134: switching circuits 26, 126: control unit                 

118a to 118n: conductor 128: shutdown signal generator

190: AND gate 192: comparator

200: lamp housing 210: diffuser plate

220: optical sheet 230: liquid crystal panel

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to a lamp driving device and a method of a liquid crystal display device capable of detecting a lamp failure by detecting an induced voltage of a lamp.

In general, liquid crystal displays (hereinafter referred to as "LCDs") have tended to be gradually widened due to their 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 displays a desired image by adjusting the transmission amount of the light beam according to the image signal.

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

As a light source used in the backlight unit, a halogen cathode fluorescent lamp (Halogen Cathode Fluorescent tube) or a cold cathode tube (cold cathode) (hereinafter referred to as "CCFL") is used. Among the light sources, CCFL is a light source tube using the cold emission (electron emission caused by the strong electric field applied to the cathode surface), and it 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.

Such a light source is classified into an internal electrode fluorescent lamp having electrodes formed inside the discharge tube and an external electrode fluorescent lamp having electrodes formed outside the discharge tube. These fluorescent lamps are driven by a high pressure AC waveform. That is, the high-voltage AC waveform for driving the fluorescent lamps 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.

Referring to FIG. 1, a lamp driving apparatus of a general LCD includes n lamps 10a to 10n (where n is a positive integer) and n lamps 10a to 10n having first and second electrodes. Inverters 20 are provided to supply high-pressure AC waveforms to each of them.

The first electrode of each of the n lamps 10a to 10n is electrically connected to the inverter 20, and the second electrode is commonly connected to the base power source. The n lamps 10a to 10n are housed inside the lamp housing, not shown. The n lamps 10a to 10n are turned on by the high-voltage AC waveform supplied from the inverter 20 to irradiate light to the liquid crystal panel stacked on the lamp housing.

The inverter 20 generates m alternating waveforms in response to a control signal (where m is a positive integer of n / 2) and alternating currents from the respective switching circuits 24a to 24m. N transformers 22a to 22n for converting the waveform into a high voltage alternating current waveform and supplying them to the first electrodes of the lamps 10a to 10n, and to the second electrodes of the lamps 10a to 10n connected in common. The detector 28 which is connected to detect the tube current of the lamp and the driving of the m switching circuits 24a to 24m and controls the m switching circuits 24a to 24m according to the feedback signal from the detector 28. A control unit 26 for shutting down is provided.

Each of the m switching circuits 24a to 24m converts a direct current supplied from the outside into an AC waveform in response to a control signal from the control unit 26 and supplies it to the n transformers 22a to 22n. At this time, one switching circuit 24 supplies an AC waveform to two transformers.

Each of the n transformers 22a to 22n boosts an AC waveform supplied from each switching circuit 24a to 24m to a high voltage AC waveform, and the boosted high voltage AC waveform is a first electrode of each lamp 10a to 10n. To feed.

The detector 28 detects the tube current of the lamp supplied through the feedback signal line 16 commonly connected to the first electrodes of the lamps 10a to 10n and supplies it to the controller 26.

The control unit 26 generates a switching control signal to control the switching of each switching circuit 24a to 24m. Then, the control unit 26 varies the switching of each switching circuit 24a to 24m or shuts down the switching circuits 24a to 24m according to the feedback signal supplied from the detection unit 28.                         

Since the lamp driving apparatus of the general liquid crystal display device has to have transformers 18a to 18n equal to the number of lamps in order to light up the plurality of lamps 10a to 10n, the cost of the inverter 20 increases. . In addition, since the lamp driving apparatus of the general liquid crystal display detects the tube current of the lamp through the second electrode of the lamp which is commonly connected, it is possible to detect when any of the plurality of lamps 10a to 10n is defective. none.

Accordingly, the present invention is to provide a lamp driving device and method of the liquid crystal display device to detect the failure of the lamp by detecting the induced voltage of the lamp to solve the above problems.

The lamp driving apparatus of the liquid crystal display according to the embodiment of the present invention for achieving the above object is a plurality of lamps having a first and a second electrode, and a high-pressure alternating current having a first phase on the first electrode A first inverter for supplying a waveform in common, a second inverter for supplying a high voltage alternating current waveform having a second phase different from the first phase to the second electrode, and attached to the respective lamps A plurality of conductors for detecting induced voltages induced in the lamps, a shutdown signal generator for generating a shutdown signal according to a feedback signal corresponding to the induced voltages supplied from the plurality of conductors, and the first and the first And controlling a second inverter and shutting down the first and second inverters according to the shutdown signal.

A lamp driving method of a liquid crystal display according to an exemplary embodiment of the present invention may include generating a first high-voltage AC waveform having a first phase by using a first inverter, and different from the first phase by using a second inverter. Generating a second high-voltage alternating current waveform having a second phase, lighting a plurality of lamps connected in parallel using the first and second high-voltage alternating current waveforms, and a plurality of lamps attached to the respective lamps Generating a shutdown signal in response to a feedback signal corresponding to an induced voltage induced in a conductor of; and shutting down the first and second inverters in accordance with the shutdown signal.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings and embodiments.

2 is a diagram illustrating a lamp driving device of a liquid crystal display according to an exemplary embodiment of the present invention.

Referring to FIG. 2, a liquid crystal display (hereinafter referred to as “LCD”) according to an exemplary embodiment of the present invention includes n lamps having first and second electrodes, where n is a positive integer. 110a to 110n, a first inverter 120 for commonly supplying a high voltage alternating current waveform to the first electrode, a second inverter 130 for supplying a high voltage alternating current waveform to the second electrode in common; N conductors 118a to 118n attached to each of the plurality of lamps 110a to 110n to detect an induced voltage induced from each of the lamps 110a to 110n, and from n conductors 118a to 118n. The shutdown signal generator 128 generates a shutdown signal SDS according to the feedback signal, and controls the first and second inverters 120 and 130, and the first and second inverters 120 according to the shutdown signal SDS. And a control unit 126 for shutting down 130.

The first electrodes of the n lamps 110a to 110n are electrically connected in parallel to the first connector 112 to receive a high voltage AC waveform from the first inverter 120. The second electrodes of the n lamps 110a to 110n are electrically connected in parallel to the second connector 114 to receive a high-voltage AC waveform from the second inverter 130. The n lamps 110a to 110n have a high voltage having an AC waveform having a first phase from the first inverter 120 and a second phase having a second phase different from the first phase from the second inverter 130. When the AC waveform is supplied and turned on, light is radiated to a liquid crystal panel (not shown). At this time, the first phase and the second phase have a phase difference of 180 degrees.

Each of the n conductors 118a through 118n is attached to the outside of the glass tube of the lamps 110a through 110n in a circular shape to correspond to an induced voltage (or induced current) induced when driving the lamps 110a through 110n. The feedback signal is supplied to the shutdown signal generator 128 through the feedback signal line 116. At this time, each of the n conductors 118a to 118n is attached to be as close as possible to the first electrode of each of the lamps 110a to 110n. The n conductors 118a to 118n may be any one of indium-tin-oxide (ITO), indium-zinc-oxide (IZO), and indium-tin-zinc-oxide (ITZO). Each of the n conductors 118a through 118n is attached to the lamps 110a through 110n so that each of the lamps 110a through 110n is driven without the influence of parasitic capacitors generated between adjacent lamps 110a through 110n. The induced voltage generated can be detected.

The first inverter 120 converts the first switching circuit 124 to generate an AC waveform in response to a control signal from the controller 126 and the AC waveform from the first switching circuit 124 to a high voltage AC waveform. And a first transformer 122 for supplying to the first connector 112.

The first switching circuit 124 converts a direct current supplied from the outside into an AC waveform in response to a control signal from the controller 126 and supplies it to the first transformer 122.

The first transformer 122 boosts the AC waveform supplied from the first switching circuit 124 to a high pressure AC waveform, and supplies the boosted high pressure AC waveform to the first connector 112.

The second inverter 130 converts the second switching circuit 134 to generate an AC waveform in response to a control signal from the control unit 126 and the AC waveform from the second switching circuit 134 to a high voltage AC waveform. And a second transformer 132 for supplying to the second connector 114.

The second switching circuit 134 converts a direct current supplied from the outside into an AC waveform in response to a control signal from the controller 126 and supplies it to the second transformer 132.

The second transformer 132 boosts the AC waveform supplied from the second switching circuit 134 to a high pressure AC waveform, and supplies the boosted high pressure AC waveform to the second connector 114.

The shutdown signal generator 128 generates a shutdown signal SDS by performing a logic operation on feedback signals supplied from the n conductors 118a to 118n, and supplies the generated shutdown signal SDS to the controller 126. In other words, the shutdown signal generator 128 has no feedback signal supplied from at least one of the n conductors 118a through 118n due to abnormal driving of at least one of the n lamps 110a through 110n. In this case, a shutdown signal SDS is generated to shut down the first and second inverters 120 and 130.

The controller 126 generates a switching control signal to control the switching of the first and second switching circuits 124 and 134. The controller 126 shuts down the first and second switching circuits 124 and 134 according to the shutdown signal SDS supplied from the shutdown signal generator 128. The controller 126 may be installed in any one of the first and second inverters 120 and 130.

As described above, the lamp driving apparatus and method of the liquid crystal display according to the exemplary embodiment of the present invention drive the n lamps 110a to 110n in parallel by using the first and second inverters 120 and 130 and all of them. The induced voltages induced by the conductors 118a through 118n attached to the lamps 110a through 110n are individually fed back, and the first and second inverters 120 and 130 are shut down according to the feedback signals.

3 is a cross-sectional view schematically illustrating a liquid crystal display according to an exemplary embodiment of the present invention.

Referring to FIG. 3 and FIG. 2, the liquid crystal display according to the exemplary embodiment of the present invention may include a lamp housing 200 accommodating n lamps 110a through 110n to which conductors 118a through 118n are attached, and a lamp housing. A diffusion plate 210 covering the 200, a plurality of optical sheets 220 stacked on the diffusion plate 210, and a liquid crystal panel 230 disposed on the optical sheet 220.

In the liquid crystal display according to the exemplary embodiment of the present invention, as described above, the n lamps 110a to 110n are formed by a high-voltage AC waveform having different phases supplied from the first and second inverters 120 and 130. ) In parallel to generate light, and the light emitted from the n lamps 110a to 110n is irradiated onto the liquid crystal panel 230 via the diffusion plate 210 and the optical sheet 220.

As described above, the liquid crystal display according to the exemplary embodiment of the present invention drives the n lamps 110a through 110n in parallel by using the first and second inverters 120 and 130 and all the lamps 110a through 110n. The induced voltages induced in the conductors 118a to 118n attached thereto are individually fed back, and the first and second inverters 120 and 130 are shut down according to the feedback signal.

4 is a diagram illustrating a shutdown signal generator 128 of the first embodiment shown in FIG. 2.

Referring to FIG. 4 and FIG. 2, the shutdown signal generator 128 according to the first embodiment performs an AND operation on the feedback signals corresponding to the induced voltages supplied from the n conductors 118a to 118n to generate a shutdown signal SDS. It consists of an AND gate that occurs.

FIG. 5 is a diagram illustrating the shutdown signal generator 128 of the second embodiment shown in FIG. 2.

5, the shutdown signal generator 128 according to the second embodiment performs an AND operation on the feedback signal corresponding to the induced voltages supplied from the n conductors 118a to 118n, and outputs an AND. Gate 190 and a comparator 192 for generating a shutdown signal SDS by comparing the output signal Vo from the AND gate 190 with the reference voltage Vref.

FIG. 6 is a diagram illustrating a shutdown signal generator 128 of the third embodiment shown in FIG. 2.

6, the shutdown signal generator 128 of the third embodiment uses a multiplexer MUX to shut down signals according to feedback signals corresponding to induced voltages supplied from the n conductors 118a to 118n. (SDS) is generated and supplied to the controller 126.

FIG. 7 is a diagram illustrating the shutdown signal generator 128 of the fourth embodiment shown in FIG. 2.

Referring to FIG. 7 and FIG. 2, the shutdown signal generator 128 of the fourth embodiment compares the feedback signals corresponding to the induced voltages supplied from each of the n conductors 118a to 118n by using a plurality of comparators. The shutdown signal SDS is generated according to the difference between the feedback signals and supplied to the controller 126.

8 is a view showing another type of conductor shown in FIG.

Referring to FIG. 8 in conjunction with FIG. 2, each of the n conductors 118a-118n is attached in the form of a strip to the outside of the glass tube of all lamps 110a-110n. At this time, each of the strip-shaped conductors 118a to 118n is attached to be as close as possible to the first electrodes of the lamps 110a to 110n.

9 is a view showing another type of conductor shown in FIG.

Referring to FIG. 9 in conjunction with FIG. 2, each of the n conductors 118a-118n is wound to surround the outside of the glass tube of all lamps 110a-110n. At this time, each of the conductors 118a to 118n wound outside the glass tube is wound to be as close as possible to the first electrode of the lamps 110a to 110n.

On the other hand, the present invention described above is not limited to the above-described embodiment and the accompanying drawings, it is possible that various substitutions, modifications and changes within the scope without departing from the technical spirit of the present invention It will be apparent to those skilled in the art.

The lamp driving apparatus and method of the liquid crystal display according to the exemplary embodiment of the present invention as described above have the following effects.

First, the present invention operates only at the time of abnormality of the lamps regardless of the initial lighting voltage of all the lamps, and can improve the reliability of the liquid crystal display by shutting down the inverter even when at least one lamp is abnormally operated.

Second, the present invention can detect the driving state of all lamps by using an individual feedback scheme.

Third, the present invention can reduce the cost of the inverter by driving n lamps in parallel.

Claims (15)

A plurality of lamps having first and second electrodes, A first inverter for commonly supplying a high voltage alternating current waveform having a first phase to the first electrode; A second inverter for commonly supplying a high voltage AC waveform having a second phase different from the first phase to the second electrode; A plurality of conductors which are directly wound on the outer circumference of the glass tube of the lamps so as to be adjacent to the first electrode to detect the induced voltage induced in the lamps; A logic product gate connected to the plurality of conductors through a feedback signal line and performing a logic operation on a feedback signal corresponding to the induced voltage supplied from the plurality of conductors, and a comparator comparing the result of the logic operation with a reference voltage. A shutdown signal generator for generating a shutdown signal; And a controller which controls the first and second inverters and shuts down the first and second inverters according to the shutdown signal. delete delete The method of claim 1, Each of the first and second inverters, A switching circuit for generating an AC waveform in response to the control from the controller; And a transformer for converting the AC waveform from the switching circuit into the high voltage AC waveform. delete delete delete delete The method of claim 1, A lamp housing accommodating the plurality of lamps; A diffusion plate covering the lamp housing; A plurality of optical sheets stacked on the diffusion plate; And a liquid crystal panel disposed on the optical sheet. Generating a first high-voltage alternating current waveform having a first phase by using a first inverter; Generating a second high voltage alternating current waveform having a second phase different from the first phase by using a second inverter; Lighting the plurality of lamps connected in parallel using the first and second high-voltage AC waveforms; Performing a logical AND operation on a feedback signal corresponding to an induced voltage induced in a plurality of conductors directly wound on the outer circumference of each glass tube so as to be as close as possible to the first electrode; Generating a shutdown signal by comparing the result of the AND operation with a reference voltage; And shutting down the first and second inverters according to the shutdown signal. 11. The method of claim 10, Generating the AC waveform of the first and second high pressure, Generating an AC waveform, And converting the alternating current waveform into the high voltage alternating current waveform. delete delete delete delete

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