KR20060019706A - Backlight assembly and display apparatus having the same - Google Patents

Abstract

Disclosed are a backlight assembly capable of light and short and a display device having the same. In the backlight assembly, a plurality of lamps are connected in parallel to each other, and receives light from a drive voltage to generate light. The inverter includes one or more piezoelectric transformers, and the piezoelectric transformer converts an input voltage provided from the outside into the driving voltage using a piezoelectric phenomenon and provides the first and second ends of each of the plurality of lamps. Therefore, the overall thickness and size of the backlight assembly and the display device can be reduced.

Description

BACKLIGHT ASSEMBLY AND DISPLAY APPARATUS HAVING THE SAME}

1 is an exploded perspective view of a backlight assembly according to an embodiment of the present invention.

FIG. 2 is a perspective view specifically showing the piezoelectric transformer shown in FIG. 1.

FIG. 3 is a circuit diagram of the piezoelectric transformer shown in FIG. 2.

4 is an output waveform diagram of the piezoelectric transformer shown in FIG. 3.

5 is a plan view of an inverter according to another embodiment of the present invention.

FIG. 6 is an output waveform diagram of the piezoelectric transformer shown in FIG. 5.

7 is an exploded perspective view of a display device according to still another embodiment of the present invention.

* Description of the symbols for the main parts of the drawings *

100: backlight assembly 200: multiple lamps

300: storage container 330, 340: first and second mold pieces

400: diffuser plate 410: light collecting sheet

600: Inverter 700: Top Chassis

800: display unit 810: liquid crystal display panel

900: display device

The present invention relates to a backlight assembly and a display device having the same. More particularly, the present invention relates to a backlight assembly and a display device having the same.

In general, a liquid crystal display device, which is one of display devices, includes a liquid crystal display panel for displaying an image using light and a backlight assembly provided under the liquid crystal display panel to provide light to the liquid crystal display panel.

The backlight assembly includes a lamp for generating light. In this case, a cold cathode fluorescent lamp (CCFL) having a tubular shape is mainly used. The backlight assembly is classified into an edge type and a direct type according to the position of the lamp.

The edge type has a structure in which one or two lamps are provided on the side of the light guide plate, and light generated from the lamp is guided to the liquid crystal display panel by the light guide plate. The direct type has a structure in which a plurality of lamps and a diffusion plate are provided below the liquid crystal display panel, and the light emitted from the plurality of lamps is diffused by the diffusion plate and then provided to the liquid crystal display panel.

The edge type is applied to a small and medium sized liquid crystal display device which requires a relatively small amount of light because the number of lamps is one or two, whereas the drop type requires a relatively large amount of light because the number of lamps is larger than that of the edge type. It is applied to a large liquid crystal display device.                         

On the other hand, the backlight assembly further includes an inverter having a transformer for receiving a low voltage AC power from the outside to boost to a high voltage AC power. Here, the high voltage output from the transformer is a driving voltage for driving the lamp.

In general, a transformer applied to an inverter is a magnetic transformer, and a high voltage AC power source is obtained by converting electrical energy into magnetic energy and then reducing it back to electrical energy. However, since the high voltage of the magnetic transformer is proportional to the number of turns of the coil and the thickness of the coil, there is a limit in reducing the size and thickness of the inverter made of the magnetic transformer. In particular, when the magnetic transformer is adopted, it is difficult to implement a light and simple liquid crystal display device.

Accordingly, it is an object of the present invention to provide a backlight assembly capable of light and small reduction.

Another object of the present invention is to provide a display device having the above-described backlight assembly.

According to an aspect of the present invention, a backlight assembly generates light in response to a driving voltage, and converts an input voltage provided from the outside into the driving voltage by using a plurality of lamps connected in parallel and a piezoelectric phenomenon to convert the driving voltage into each of the plurality of lamps. An inverter consisting of one or more piezoelectric transformers serving the first and second ends.

According to another aspect of the present invention, a display apparatus includes a display panel displaying an image using light, and a backlight assembly provided under the display panel to provide the light to the display panel.

The backlight assembly generates light in response to a driving voltage, and converts a plurality of lamps connected in parallel, an accommodating container accommodating the plurality of lamps and the display panel, and an input voltage provided from the outside using a piezoelectric phenomenon as the driving voltage. And an inverter provided on the rear surface of the storage container, wherein the inverter comprises one or more piezoelectric transformers which are converted to and provided to the first and second ends of each of the plurality of lamps.

According to such a backlight assembly and a display device having the same, an inverter for driving a plurality of lamps connected in parallel includes one or more piezoelectric transformers, thereby reducing the overall size and thickness of the backlight assembly, and as a result, the light and small size of the display device is reduced. It is possible to paint.

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

1 is an exploded perspective view showing in detail the backlight assembly according to an embodiment of the present invention.

Referring to FIG. 1, a backlight assembly 100 according to an embodiment of the present invention includes a plurality of lamps 200 generating light, a diffuser plate 400 disposed on the plurality of lamps 200, and the It includes a plurality of lamps 200 and the storage container 300 for receiving the diffusion plate 400.

The lamps 200 are disposed parallel to each other on the same plane and connected in parallel to each other to generate light. Each of the lamps 200 may include, for example, a cold cathode fluorescent lamp (CCFL) having a tubular shape. The backlight assembly 100 further includes a lamp holder 210 for fixing the lamps 200. Both ends of each of the lamps 200 are fitted into and fixed to the lamp holder 210. For example, two lamps adjacent to each other are coupled to the lamp holder 210. The plurality of lamps 200 coupled to the lamp holders 210 are stored in the storage container 300.

The storage container 300 includes a bottom portion 310 and a side portion 320 extending from the bottom portion 310 to form an accommodation space. The storage container 300 is made of, for example, a metal material.

The diffusion plate 400 has a rectangular plate shape having a predetermined thickness and is disposed above the lamps 200 to diffuse the light emitted from the lamps 200 to improve luminance uniformity. The diffusion plate 400 is supported by the support member 500.

Each of the support members 500 is coupled to the bottom 310 of the storage container 300 and has at least one lamp fixing part 510 for fixing each of the lamps 200. The lamp fixing part 510 has an opening 512 into which the lamp 200 is inserted. Each of the support members 500 further includes a diffusion plate support part 520 for supporting the diffusion plate 400. The diffusion plate support part 520 protrudes higher than the lamp fixing part 510 to contact the bottom surface of the diffusion plate 400.

The backlight assembly 100 further includes a light collecting sheet 410 disposed on the diffusion plate 400. The light collecting sheet 410 collects light emitted through the diffusion plate 400 in the front direction to improve front brightness of the light. Two or more light collecting sheets 410 may be formed. In addition, although not shown, the backlight assembly 100 further includes a diffusion sheet provided on the upper or lower portion of the light collecting sheet 410. The diffusion sheet diffuses the light passing therethrough to further improve luminance uniformity.

In addition, the backlight assembly 100 further includes first and second mold pieces 330 and 340 disposed corresponding to both end regions of the lamps 200. The first and second mold pieces 330 and 340 cover both ends of the lamps 200 and are coupled to the storage container 300. The first and second mold pieces 330 and 340 shield both ends of the lamps 200 having lower luminance than other regions to prevent uneven brightness of light emitted from the backlight assembly 100. In addition, the first and second mold pieces 330 and 340 support the diffusion plate 400 disposed thereon to guide the position of the diffusion plate 400.

The backlight assembly 100 further includes an inverter 600 disposed on a rear surface of the storage container 300 and generating first and second driving voltages for driving the lamps 200.

The inverter 600 includes a plurality of piezoelectric transformers 610 connected in parallel. The plurality of piezoelectric transformers 610 boost the low-voltage AC power applied from the outside to high-voltage AC power to issue the first and second driving voltages. The first and second driving voltages generated from the inverter 600 are applied to the respective lamps 200 by the first and second lamp wires 601 and 602. Specifically, one end of each lamp 200 is connected to the inverter 600 through a first lamp wire 601 to receive the first driving voltage, and the other end of each lamp 200 is a second lamp wire ( It is connected to the inverter 600 through 602 to receive the second driving voltage. Here, the number of the plurality of piezoelectric transformers 610 is less than or equal to the number of the plurality of lamps 200.

Each of the piezoelectric transformers 610 is an intermediate existence of a ignition element and a filter to which the piezoelectric effect is applied. The piezoelectric transformers 610 have a function of combining the two, and the electrical energy is converted into mechanical energy and then reduced back into electrical energy. The process obtains high voltage AC power. Unlike the general magnetic transformer using magnetic flux, each of the piezoelectric transformers 610 applies a piezoelectric phenomenon and a resonance phenomenon of a piezoelectric ceramic element, which is a dielectric, so that the structure is simple and easy to manufacture. In addition, it is possible to reduce the size and the overall size of the inverter 600 can be reduced. In general, the thickness of the magnetic transformer is 7 ~ 10mm, while the thickness of the piezoelectric transformer 610 as an example of the present invention is 3mm.

FIG. 2 is a perspective view showing in detail the piezoelectric transformer shown in FIG. 1, FIG. 3 is an equivalent circuit diagram of the inverter and the lamp shown in FIG. 1, and FIG. 4 is an output waveform diagram of the piezoelectric transformer shown in FIG. 3.

Referring to FIG. 2, the piezoelectric transformer 610 may include a piezoelectric ceramic element having a predetermined thickness, first and second input electrodes 612 and 613 provided on upper and lower surfaces of the piezoelectric ceramic element 611, respectively. The output electrode 614 is provided on one side of the piezoelectric ceramic element 611.

The first and second input electrodes 612 and 613 are connected to the first and second terminals of the power supply 620 to receive the low voltage AC power from the power supply 620. Thereafter, the piezoelectric ceramic element 611 is excited and vibrated by the piezoelectric effect. In this case, the mechanical stress is moved in the polarization direction A of the piezoelectric ceramic element 611, and as a result, the output electrode 614 is connected to the voltages applied to the first and second input electrodes 612 and 613. A high voltage AC power source having the same frequency is output.

The output electrode 614 is electrically connected to the first end 201 of the lamp 200. Therefore, the high voltage AC power output from the piezoelectric transformer 610 is provided to the first end 201 of the lamp 200. Meanwhile, the ground voltage VSS is applied to the second end 202 of the lamp 200.

As shown in FIG. 4, the second driving voltage Vcold provided to the second end 202 of the lamp 200 is a bias voltage for maintaining a predetermined voltage level, and the first end of the lamp 200. The first driving voltage Vhot provided to the 201 is a sinusoidal AC voltage swinging on the basis of the second driving voltage Vcold. The lamp 200 generates light in response to the voltage difference between the first and second driving voltages Vhot and Vcold. As an example of the present invention, the bias voltage is a ground voltage VSS.

Meanwhile, referring to FIG. 3, in one embodiment of the present invention, the power supply unit 620 has a full bridge structure. The power supply unit 620 includes first, second, third and fourth switching elements Tr1, Tr2, Tr3, and Tr4. The first and second switching elements Tr1 and Tr2 are connected to the first input electrode 612 of the piezoelectric transformer 610 through a resonant filter inductor 630, and the third and fourth switching elements ( Tr3 and Tr4 are connected to the second input electrode 613.

The second input electrode 613 is connected to an output terminal of the third switching element Tr3, and a bias voltage having a ground level or a DC level of the input voltage Vin is input to the second input electrode 613. . On the other hand, a sine wave swinging on the first input electrode 612 with a positive or negative value based on the bias voltage due to resonance by the inductor 630 during the time when the first switching element Tr1 is turned on. AC voltage is applied.

5 is a plan view of an inverter according to another embodiment of the present invention, and FIG. 6 is an output waveform diagram of the piezoelectric transformer shown in FIG. 5.

Referring to FIG. 5, an inverter 600 according to another embodiment of the present invention includes a plurality of piezoelectric transformers 650. Each of the piezoelectric transformers 550 includes a piezoelectric ceramic element 651 having a predetermined thickness, first and second input electrodes 652 and 653 provided on upper and lower surfaces of the piezoelectric ceramic element 651, respectively. First and second output electrodes 654 and 655 are provided on both sides of the piezoelectric ceramic element 651, respectively.

The first and second input electrodes 652 and 653 are connected to first and second terminals of the power supply unit 660, respectively, to receive the low voltage AC power from the power supply unit 660. Thereafter, the piezoelectric ceramic element 651 is excited by the piezoelectric effect and vibrates. As a result, a high voltage AC power source having the same frequency as the voltages applied to the first and second input electrodes 652 and 653 is output to the first and second output electrodes 654 and 655.

The first output electrode 654 is electrically connected to the first end 201 of the lamp 200, and the second output electrode 655 is electrically connected to the second end 202 of the lamp 200. Connected. Therefore, the high voltage AC power output from the piezoelectric transformer 650 is provided to the first and second ends 201 of the lamp 200.

As shown in FIG. 6, the first driving voltage Vhot provided to the first end 201 of the lamp 200 is a sinusoidal wave swinging with a predetermined frequency, and the second end of the lamp 200. The second driving voltage VSS provided to 202 swings with a phase inverted with the first driving voltage Vhot. Therefore, the lamp 200 generates light in response to the voltage difference between the first and second driving voltages Vhot and Vcold.

Referring back to FIG. 5, the inverter 600 further includes a controller 670 for controlling the driving of the power supply unit 660.

The piezoelectric transformer 650 shown in FIGS. 2 to 6 is a Lawson-type transformer, manufactured by Lawson in 1956. However, in the present invention, the piezoelectric transformer 650 is not limited to the Lawson-type structure, and for example, a multilayer piezoelectric transformer may be employed. Description of the structure of the stacked piezoelectric transformer is omitted.

7 is an exploded perspective view of a display device according to still another embodiment of the present invention. However, the same reference numerals are given to the same components as those illustrated in FIG. 1 among the components illustrated in FIG. 7, and detailed description thereof will be omitted.

Referring to FIG. 7, the display device 900 according to another exemplary embodiment of the present invention may include a display unit 800 for displaying an image using light and a lower portion of the display unit 800. And a backlight assembly 100 for supplying the light to 800.

The display unit 800 includes a liquid crystal display panel 810 for displaying an image, data and gate printed circuit boards 820 and 830 for providing a driving signal for driving the liquid crystal display panel 810. Each of the data and gate printed circuit boards 820 and 830 is electrically connected to the liquid crystal display panel 810 through a data and gate tape carrier package (hereinafter, referred to as TCP) 840 and 850. . Each of the data and gate TCPs 840 and 850 includes data and gate driving chips 842 for applying driving signals provided from the data and gate printed circuit boards 820 and 830 to the liquid crystal display panel 810 at an appropriate timing. 852 is mounted.

The gate printed circuit board 830 may be removed by electrically connecting the gate TCP 850 and the data printed circuit board 820.

The liquid crystal display panel 810 includes a thin film transistor (TFT) substrate 812, a color filter substrate 814 coupled to the TFT substrate 812, and the TFT substrate 812. And a liquid crystal layer 816 interposed between the color filter substrate 814.

The TFT substrate 812 is a transparent glass substrate on which a switching element TFT (not shown) is formed in a matrix form. Data and gate lines are respectively connected to the source and gate terminals of the TFTs, and a pixel electrode (not shown) made of a transparent conductive material is connected to the drain terminal.

The color filter substrate 814 is a substrate on which an RGB pixel (not shown) which is a color pixel and a common electrode (not shown) made of a transparent conductive material are formed.

When power is applied to the gate terminal of the TFT and the TFT is turned on, an electric field is formed between the pixel electrode and the common electrode. The arrangement of the liquid crystal 816 interposed between the TFT substrate 812 and the color filter substrate 814 is changed by this electric field. As the arrangement of the liquid crystal 816 changes, the transmittance of the light supplied from the backlight assembly 100 is changed to display an image having a desired gray scale.

The display device 900 is coupled to face the edge of the liquid crystal display panel 810 so as to be opposed to the storage container 300 to fix the liquid crystal display panel 810 to the storage container 300. And further includes 700. The top chassis 700 prevents the liquid crystal display panel 810 from being damaged by an external impact, and prevents the liquid crystal display panel 810 from being separated from the storage container 300.

1 to 7 illustrate only a structure in which the lamps 200 employed in the backlight assembly 100 are cold cathode fluorescent lamps. However, the piezoelectric transformer 610 proposed in the present invention may be sufficiently applied to a backlight employing not only a cold cathode fluorescent lamp but also an external electrode fluorescent lamp (not shown).

According to such a backlight assembly and a display device having the same, an inverter for driving a plurality of lamps connected in parallel is provided with a plurality of piezoelectric transformers that can be formed relatively thinner than magnetic transformers, thereby reducing the overall size and thickness of the backlight assembly. It is possible to reduce, and as a result, the light and small size of the display device is possible.

Although described with reference to the embodiments above, those skilled in the art will understand that the present invention can be variously modified and changed without departing from the spirit and scope of the invention as set forth in the claims below. Could be.

Claims (9)

A plurality of lamps generating light in response to the driving voltage and connected in parallel; And And an inverter composed of at least one piezoelectric transformer converting an input voltage provided from the outside into a driving voltage using a piezoelectric phenomenon and providing the plurality of lamps to each of the plurality of lamps. The piezoelectric transformer of claim 1, wherein each of the piezoelectric transformers comprises: Piezoelectric elements; First and second input electrodes provided on upper and lower surfaces of the piezoelectric element, respectively, to receive the input voltage from the outside; And And an output electrode provided on one surface of the piezoelectric element to output a first driving voltage among the driving voltages. The method of claim 2, wherein the one or more piezoelectric transformers output a second driving voltage to maintain a predetermined voltage level among the driving voltages, and provide the second driving voltage to a first end of each of the plurality of lamps. The first driving voltage is an AC voltage swinging on the basis of the second driving voltage, and is provided to the second end of each of the plurality of lamps. The piezoelectric transformer of claim 1, wherein each of the piezoelectric transformers comprises: Piezoelectric elements; First and second input electrodes provided on upper and lower surfaces of the piezoelectric element to receive the input voltage from the outside; And And first and second output electrodes provided on both surfaces of the piezoelectric element to output the driving voltage, respectively. The method of claim 4, wherein the driving voltage includes first and second driving voltages which are AC voltages swinging with phases inverted from each other. And the first and second driving voltages are provided to first and second ends of each of the plurality of lamps, respectively. The backlight assembly of claim 1, wherein each of the plurality of lamps is a cold cathode fluorescent lamp. The backlight assembly of claim 1, wherein the number of piezoelectric transformers is equal to or less than the number of lamps. A display panel displaying an image using light; And A backlight assembly provided under the display panel to provide the light to the display panel; The backlight assembly, A plurality of lamps generating light in response to the driving voltage and connected in parallel; A storage container accommodating the plurality of lamps and the display panel; And And an inverter made of at least one piezoelectric transformer converting an input voltage provided from the outside into a driving voltage by using a piezoelectric phenomenon and providing the first and second ends of the plurality of lamps, respectively. The display device of claim 8, wherein the inverter is disposed on a rear surface of the storage container.

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