KR101688562B1 - Liquid crystal display device - Google Patents

Abstract

A liquid crystal display device according to an embodiment of the present invention includes a cover bottom formed to penetrate the back surface from the top surface and having a plurality of holes for discharging humming noise generated in the liquid crystal display device to the back surface, A liquid crystal panel that displays an image by adjusting the amount of light transmitted from the backlight unit according to an input video signal, and at least one reinforcing bar disposed on the backside of the cover bottom to reinforce the rigidity of the cover bottom.

Description

[0001] LIQUID CRYSTAL DISPLAY DEVICE [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display, and more particularly, to a liquid crystal display capable of improving the structure of a cover bottom to reduce front humming noise due to driving.

In the information society, the importance of display devices as visual information delivery media is further emphasized. Recently, various kinds of flat panel display devices have been developed and applied to portable information devices and IT products.

 Among the flat panel display devices, liquid crystal display devices (LCDs) are suitable for portable devices due to advantages such as light weight, thin shape, and low power consumption driving, and are applied to various fields such as notebook computers, monitors, spacecrafts and aircrafts.

1 is a view showing a conventional liquid crystal display device.

Referring to FIG. 1, a liquid crystal display according to the related art displays an image by adjusting a light transmittance of each liquid crystal cell according to an input image signal. The liquid crystal display device includes a liquid crystal panel 10 in which liquid crystal cells are arranged in a matrix form, a backlight unit 30 including a backlight 30 for supplying light to the liquid crystal panel 10, And a driving circuit 60 for driving the backlight 30. The liquid crystal display device includes a support main 32 and a cover bottom 20. The liquid crystal panel 10 and the backlight unit are mounted on the cover main 20 and mounted on the cover main 20.

The liquid crystal panel 10 includes a lower substrate including a plurality of gate lines GL1 to GLn, a plurality of data lines DL1 to DLm and a thin film transistor (TFT) .

Liquid crystal cells are defined by intersection of a plurality of gate lines and a plurality of data lines formed on the lower substrate, and pixel electrodes and common electrodes for applying an electric field are formed in each liquid crystal cell. Each of the liquid crystal cells is switched through the thin film transistor. The liquid crystal panel 10 is connected to a gate driver for supplying a scan signal to the gate line and a data driver for supplying a video signal to the data line.

The driving circuit 60 includes a power source for supplying power for driving the liquid crystal panel 10 and an inverter for driving the backlight 30.

Since the liquid crystal panel 10 is formed of a light receiving element having no light emitting element, a separate light source must be provided. The liquid crystal display device includes a backlight 30 for generating light to be supplied to the liquid crystal panel 10, a diffusion plate 40 for diffusing light from the backlight 30, And a backlight unit constituted by a plurality of optical sheets 50 for improving the efficiency of light supplied to the panel 10.

The backlight 30 may be a cold cathode fluorescent lamp (CCFL), an electro fluorescent lamp (EEFL), or a light emitting diode (LED) An external electrode fluorescent lamp is applied as a backlight.

The backlight unit is divided into a direct-type type and an edge type according to the form in which the backlight 30 is disposed. In the edge type, a backlight 30 is disposed in a lateral direction of the liquid crystal panel 10, and the light from the backlight 30 is irradiated to the liquid crystal panel 10 through a light guide plate (not shown) There is an advantage in slimming down.

In the direct type system, a plurality of backlights 30 are disposed on the back surface of the liquid crystal panel 10, and the light generated by the plurality of backlights 30 is directly irradiated onto the entire surface of the liquid crystal panel 10, The light efficiency is high. Since the direct type liquid crystal panel 10 generates light through a plurality of backlights 30, the liquid crystal panel 10 can be illuminated with a high luminance light and is applied to a liquid crystal display device having a large screen.

The cover bottom 20 has a predetermined space therein and the plurality of backlight 30, the diffuser plate 40, the optical sheet 50 and the liquid crystal panel 10 described above are seated on the support main body 32, And is mounted in the inner space of the bottom 20.

2, a reinforcing bar 70 is disposed on the back surface of the cover bottom 20 so that the liquid crystal display device can be used as a liquid crystal display device. Thereby preventing occurrence of a problem of warping or turning.

3 is a cross-sectional view showing a part of the liquid crystal display according to the related art taken along the line A-A 'in FIG.

3, a plurality of backlights 30, a diffusion plate 40, an optical sheet 50, and a liquid crystal panel 10 are mounted in a modular form in the inner space of the cover bottom 20, . Therefore, the liquid crystal display device is structurally prevented from efficiently dispersing humming noise generated therein.

The backlight 30 generates resonance noise and humming noise according to the internal resonance according to the driving frequency at the time of driving. The humming noise caused by the driving of the backlight 30 acts as an obstacle to the user's viewing of the video and audio .

Generally, the permissible value of the humming noise according to the driving of the liquid crystal display device is different depending on the front and back. The front humming noise is required to be 19 dB or less and the rear humming noise is required to be 23 dB or less have.

Referring to FIG. 4, the measurement of the humming noise was performed on five samples of the liquid crystal display according to the related art. As a result, it can be confirmed that the back humming noise satisfies the requirements of 23 dB or less .

However, in the case of the front humming noise, when the dimming of 20% to 40% is applied at the driving frequency of 100 Hz (PAL system), the requirement of 19 dB or less can not be satisfied.

In particular, in the case of a liquid crystal display device having a large screen, the number of backlights 30 increases in proportion to the size of the liquid crystal panel. In this case, the humming noise due to the resonance of the backlight is further increased (particularly, the front humming noise is increased). Accordingly, in the case of a large-screen liquid crystal display device, the front humming noise exceeding the allowable standard of 19 dB is further increased with an increase in the number of backlights 30, thereby hindering the user's viewing of video and audio.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a liquid crystal display capable of improving the structure of a cover bottom and a reinforcing bar to reduce front humming noise due to driving.

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SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a liquid crystal display device capable of improving the quality of a user's visual and audio viewing.

A liquid crystal display device according to an embodiment of the present invention includes a cover bottom formed to penetrate the back surface from the top surface and having a plurality of holes for discharging humming noise generated in the liquid crystal display device to the back surface, A liquid crystal panel that displays an image by adjusting the amount of light transmitted from the backlight unit according to an input video signal, and at least one reinforcing bar disposed on the backside of the cover bottom to reinforce the rigidity of the cover bottom.

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The reinforcing bar of the liquid crystal display according to the embodiment of the present invention is disposed at a position corresponding to a plurality of holes formed in the cover bottom.

The reinforcing bar of the liquid crystal display device according to the embodiment of the present invention is formed in the shape of a bar having a cross section of "Π" or "Μ", and is symmetrical to the left and right with respect to the center of the bottom surface of the cover bottom Respectively.

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The reinforcing bar of the liquid crystal display device according to the embodiment of the present invention includes a plurality of holes for discharging the humming noise generated inside the liquid crystal display device to the back surface of the liquid crystal display device.

The plurality of holes formed in the reinforcing bars of the liquid crystal display device according to the embodiment of the present invention are formed in a "" shape on the left side and the right side of the reinforcing bar.

The liquid crystal display device according to the embodiment of the present invention improves the structure of the cover bottom and the reinforcing bar, thereby reducing the front humming noise due to driving.

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The liquid crystal display according to the embodiment of the present invention includes a plurality of first holes formed in the back surface of the cover bottom and a plurality of second holes formed in the left and right wall surfaces of the reinforcing bar, The front humming noise of the apparatus can be reduced.

The liquid crystal display device according to the embodiment of the present invention can improve the quality of the user's video and audio viewing by improving the front humming noise.

1 is a perspective view showing a conventional liquid crystal display device.
2 is a plan view showing a rear surface of a liquid crystal display device according to the related art.
FIG. 3 is a cross-sectional view showing a part of the liquid crystal display according to the related art cut along the line AA 'in FIG. 2;
4 is a diagram showing measurement results of front and rear humming noises of a liquid crystal display according to a related art.
5 is a perspective view illustrating a liquid crystal display device according to an embodiment of the present invention.
6 and 7 are plan views showing a back surface of a liquid crystal display device according to an embodiment of the present invention.
8 is a cross-sectional view showing a part of the liquid crystal display device according to the embodiment of the present invention taken along line BB 'of FIG. 7;
9 is a perspective view showing a cover bottom and a reinforcing bar of a liquid crystal display device according to an embodiment of the present invention.
10 is a diagram showing measurement results of front and rear humming noises of a liquid crystal display device according to an embodiment of the present invention.

Hereinafter, a driving apparatus and a driving method of a liquid crystal display according to an embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 5 is a perspective view showing a liquid crystal display device according to an embodiment of the present invention, and FIGS. 6 and 7 are plan views showing a back surface of a liquid crystal display device according to an embodiment of the present invention.

5 to 7, a liquid crystal display 100 including a cover bottom 120 according to an embodiment of the present invention includes a liquid crystal panel 110, a liquid crystal panel 110 for supplying light to the liquid crystal panel 110, A backlight unit, and a driving circuit 160 for driving the liquid crystal panel 110 and the backlight 130.

The liquid crystal display device 100 includes a support main 132 and a cover bottom 120. The liquid crystal panel 110 and the backlight unit are mounted on the support main 132 and mounted on the cover bottom 120. [ do.

The liquid crystal panel 110 includes a lower substrate including n gate lines G1 through Gn and m data lines D1 through Dm and a thin film transistor .

And a liquid crystal cell (Clc, pixel region) formed for each region defined by the intersection of the n gate lines (G1 through Gn) and the m data lines (D1 through Dm) formed on the lower substrate, A pixel electrode and a common electrode for applying an electric field are formed.

Each of the liquid crystal cells Clc includes a thin film transistor TFT and a storage capacitor Cst formed at intersections of the gate lines G1 to Gn and the data lines D1 to Dm, Are switched through the thin film transistor.

The liquid crystal panel 110 is connected to a gate driver for supplying a scan signal to the gate line and a data driver for supplying a video signal to the data line. The thin film transistor TFT includes gate lines G1 to Gn, And supplies analog data signals from the data lines D1 to Dm to the liquid crystal cell Clc in response to a scan signal supplied through the data lines D1 to Dm.

The driving circuit 160 includes a power source for supplying power for driving the liquid crystal panel 110 and an inverter for driving the backlight 130.

The backlight unit includes a plurality of backlights 130 for generating light to be supplied to the liquid crystal panel 110, a diffusion plate 140 for diffusing light from the backlight 130, And a plurality of optical sheets 150 for improving the efficiency of light supplied to the light guide plate 110.

Here, the backlight 130 may be a cold cathode fluorescent lamp (CCFL), an electro fluorescent lamp (EEFL), a light emitting diode (LED) An external electrode fluorescent lamp (EEFL) is applied to the organic light emitting diode 130.

The cover bottom 120 is formed to have a bottom surface and a side wall surface extending from the bottom surface, and a predetermined space is provided in the inside. The plurality of backlights 130, the diffusion plate 140, the optical sheet 150 and the liquid crystal panel 110 described above are mounted on the support main body 132 in the inner space of the cover bottom 120.

7, the liquid crystal display device 110 according to the embodiment of the present invention may have a structure in which a reinforcing bar (not shown) is formed on the back surface of the cover bottom 120, (170) is arranged to prevent the liquid crystal display device (100) from being bent or broken.

FIG. 8 is a cross-sectional view showing a part of the liquid crystal display device according to the embodiment of the present invention taken along line BB 'of FIG. 7, and FIG. 9 is a view showing a cover bottom and a reinforcing bar of the liquid crystal display device according to an embodiment of the present invention. It is a perspective view.

8 and 9, the reinforcing bar 170 may be formed in the shape of a bar having a cross section of "Π" or "M", and the left and right sides of the reinforcing bar 170 A plurality of second holes 172 to be described later are formed. 8 and 9, the reinforcement bar 170 having a cross section of the " M "shape is shown as an example.

A plurality of first holes 122 are formed in the cover bottom 120 to discharge humming noise caused by resonance of the plurality of backlights 130 to the back surface of the liquid crystal display device 100.

The plurality of first holes 122 are formed to penetrate the back surface from the upper surface of the cover bottom 120 so as to be symmetrical to the left and right sides with respect to the center of the cover bottom 120 as shown in FIG. .

5 and 6, the plurality of first holes 122 are formed to be symmetrical with respect to a predetermined position of the cover bottom 120 in two rows, but the positions where the plurality of first holes 122 are formed And may be formed at an appropriate position where the humming noise can be discharged to the back surface of the liquid crystal display device 100. However, in order to prevent the user from perceiving the plurality of first holes 122, the plurality of first holes 122 may correspond to the positions where the reinforcing bars 170 are disposed, .

The number of the plurality of first holes 122 and the ratio of the number of the first holes 122 to the total area of the cover bottom 120 is not limited but affects the rigidity of the cover bottom 120 The plurality of first holes 122 may be formed.

In an embodiment of the present invention, fifteen first holes 122 are formed on the left and right sides of the cover bottom 120 so as not to affect the rigidity of the cover bottom 120, . The plurality of first holes 122 are formed so that the total area of the cover bottom 120 is 15% to 20% of the area where the reinforcing bar 170 is disposed.

In order to reduce the front humming noise, the humming noise generated in the liquid crystal display device 100 is smoothly transmitted to the back surface of the liquid crystal display device 100 through the plurality of first holes 122 formed in the cover bottom 120 Be discharged.

8 and 9, in order to allow the humming noise discharged through the first hole 122 to be discharged to the back surface of the liquid crystal display device 100, the left side of the reinforcing bar 170 And a plurality of second holes 172 are formed on the right side.

The plurality of second holes 172 formed in the reinforcing bar 170 may correspond to the plurality of first holes 122 formed in the cover bottom 120. For example, Eight second holes 172 each having a size of 2.5 x 30 mm are formed on the left side and the right side of the first electrode 170, respectively.

A plurality of first holes 122 are formed in the cover bottom 120 and a plurality of first holes 122 are formed on the left and right sides of the reinforcing bars 170 so as to correspond to the plurality of first holes 122. [ By forming the two holes 172, the humming noise generated inside the liquid crystal display device can be discharged toward the back surface of the liquid crystal display device 100, thereby reducing the front humming noise. In addition, the first holes 122 may be formed so as to correspond to the positions where the reinforcing bars 170 are disposed, so that the first holes 122 may not be recognized from the outside.

In the drawings for explaining the present invention, the plurality of first holes 122 formed in the cover bottom 120 have a shape of "O", and the plurality of first holes 122 formed in the reinforcing bar 170 And the second hole 172 has a "" shape.

However, there is no limitation on the shape of the plurality of first holes 122 and the plurality of second holes 172. In addition to the shape of "" and the shape of "" The plurality of first holes 122 and the plurality of second holes 172 may be formed to have a predetermined shape capable of smoothly discharging the generated humming noise toward the back surface of the liquid crystal display device.

Although the liquid crystal display device to which the reinforcing bar 170 is applied is described as an example in the above description, the liquid crystal display device to which the reinforcing bar 170 is not applied is not limited to the cover bottom 120 The effect of reducing the front humming noise can be obtained.

As described above, the permissible value of the humming noise due to the driving of the liquid crystal display device is required to be 19 dB or less in the case of the front humming noise and 23 dB or less in the case of the rear humming noise.

In order to realize a high brightness (e.g., 600 [nits]), the number of the backlight 130 increases as the liquid crystal display device applies the large screen. In general, 30 backlights 130 are applied.

In the present invention, when the cover bottom 120 in which the plurality of first holes 122 are formed and the reinforcing bar 170 in which the plurality of second holes 172 are formed are applied to the liquid crystal display device 100, Experiments were conducted to see if the noise satisfied the tolerance. Here, experiments were conducted on five samples of the liquid crystal display device including 30 backlights 130, and the results are shown in FIG.

As shown in FIG. 4, when humming noise is measured on five samples of a liquid crystal display device according to the related art, as shown in FIG. 10, a 100 Hz (PAL) It can be confirmed that the front humming noise does not satisfy the requirement of 19 dB or less when the dimming of 20% to 40% is applied to the frequency.

On the other hand, as shown in FIG. 10, in the case of applying the present invention according to the embodiment, when the dimming of 20% to 80% is applied at the driving frequencies of 100 Hz and 120 Hz in all five samples, the front humming noise is 19 dB or less It is possible to confirm that the requirement is satisfied.

In addition, although the humming noise generated inside was discharged to the back surface of the liquid crystal display device 100, when the dimming of 20% to 80% was applied at the driving frequencies of 100 Hz and 120 Hz in all five samples, the rear humming noise was 23 dB or less It can be confirmed that the requirements of

Therefore, the humming noise generated in the liquid crystal display device through the cover bottom 120 including the plurality of first holes 122 can be discharged to the back surface, thereby reducing the front humming noise of the liquid crystal display device, and the rear humming noise The requirement of 23 dB or less can be satisfied. By improving the front humming noise, the user can improve the quality of the video and audio viewing.

It will be understood by those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

100: liquid crystal display device 110: liquid crystal panel
120: cover bottom 122: first hole
130: Backlight 132: Support Main
140: diffusion plate 150: optical sheet
160: drive circuit 170: rigid bar
172: second hole

Claims (9)

A cover bottom formed to penetrate the back surface from an upper surface and including a plurality of first holes for discharging humming noise generated inside the liquid crystal display device to the back surface;
A backlight unit mounted on the cover bottom;
A liquid crystal panel for displaying an image by adjusting a transmission amount of light supplied from the backlight unit according to an input video signal; And
And at least one reinforcement bar disposed on a back surface of the cover bottom to reinforce the rigidity of the cover bottom,
And the reinforcing bar is disposed at a position corresponding to the plurality of first holes. The method according to claim 1,
Wherein the plurality of first holes
Wherein the cover bottom is symmetrically disposed on the left and right sides with respect to the center of the bottom surface of the cover bottom. The method according to claim 1,
And each of the plurality of first holes has a shape of "? &Quot; delete delete The method according to claim 1,
The reinforcing bar
Wherein the liquid crystal display device has a bar shape having a cross section of a "?"Shape or a" M "shape, and is arranged symmetrically on the left and right sides with respect to a central portion of the bottom surface of the cover bottom. The method according to claim 1,
The reinforcing bar
And a plurality of second holes for discharging the humming noise generated in the liquid crystal display device to a back surface of the liquid crystal display device. 8. The method of claim 7,
Wherein the plurality of second holes
Is formed in a "?" Shape on the left side surface and the right side surface of the reinforcing bars. 8. The method of claim 7,
And each of the plurality of second holes is formed to have a size of 2.5 x 30 mm.

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