KR20080000359A - Back light unit and liquid crystal display using the same - Google Patents

Abstract

A backlight unit and an LCD using the same are provided to prevent bending of optical sheets by installing a net between lamps and optical sheets. A bottom cover(54) receives light sources, and has an opened upper surface. A net(60) is separated from the light sources over the light sources, and have both ends fixed to upper ends of sidewalls of the bottom cover to cross the opened surface of the bottom cover. At least one optical sheet(56) is disposed on the net. The net includes a first support line crossing the opened surface of the bottom cover along a first direction, and a second support line crossing the opened surface of the bottom cover along a second direction crossing the first direction.

Description

Back light unit and liquid crystal display using the same

1 is a perspective view showing a liquid crystal display device employing a conventional direct type backlight unit.

FIG. 2 is a cross-sectional view illustrating a deflection phenomenon of the optical sheets illustrated in FIG. 1. FIG.

3 is a cross-sectional view of the backlight unit illustrated in FIG. 1.

4 is a perspective view showing a backlight unit according to a first embodiment of the present invention;

FIG. 5 is a cross-sectional view illustrating the backlight unit of FIG. 4. FIG.

6 to 9 show other embodiments of the net shown in FIG. 4.

10 is a perspective view of a liquid crystal display according to a second exemplary embodiment of the present invention.

<Description of Symbols for Main Parts of Drawings>

50 lamps 52 reflector

54 bottom cover 56 optical sheets

58: liquid crystal display panels 60, 70, 72, 74, 76, 80: net

The present invention relates to a backlight unit, and more particularly to a backlight unit to prevent sagging of optical sheets without a diffuser plate. In addition, the present invention relates to a liquid crystal display device that can be reduced in weight and thickness by using the backlight unit.

In general, the liquid crystal display device has a trend that the application range is gradually widened due to the characteristics such as light weight, thin, low power consumption. In accordance with this trend, liquid crystal displays are used in office automation equipment, audio / video equipment, and the like. In such a liquid crystal display, a light transmittance is adjusted according to a signal applied to a plurality of control switches arranged in a matrix to display a desired image on a screen.

The liquid crystal display device includes a liquid crystal display module, a driving circuit unit and a case for driving the liquid crystal display module. Since the liquid crystal display module is not a self-luminous display device, a separate light source such as a backlight unit is required.

The backlight unit includes a direct type and an edge type according to the position of the light source. The edge type backlight unit installs a light source at one edge of the liquid crystal display module and irradiates the liquid crystal display panel with light incident from the light source through the light guide plate and the plurality of optical sheets. The direct type backlight unit arranges a plurality of light sources directly under the liquid crystal display, and irradiates the liquid crystal display panel with light incident from the light sources through the diffusion plate and the plurality of optical sheets.

Referring to FIG. 1, the conventional direct type backlight unit includes a liquid crystal display panel 22, a diffusion plate 18, and optical sheets 20 disposed between the liquid crystal display panel 22 and a plurality of lamps 12. ), A bottom cover 16 for receiving a plurality of lamps 12, and a reflecting plate 14 on the inner bottom of the bottom cover 16.

In order to apply a voltage to the lamps 12, the electrode lead wire 10 protruding from both ends of the lamps 12 is connected to the lamp driving circuit (or inverter) through a connector (not shown).

The diffuser plate 18 diffuses the light incident from the lamps 12. The diffusion plate 18 includes a plurality of beads in polymethylmethacrylate (PMMA) and scatters the light incident from the lamps 12 using the beads.

The optical sheets 20 include a diffusion sheet for diffusing light incident from the diffusion plate 18 and prism sheets for advancing light in a direction perpendicular to the display surface of the liquid crystal display panel 22.

The bottom cover 16 accommodates lamps 12 in its inner space and attaches a reflector 14 to the bottom under the lamps 12.

The direct type backlight unit has an advantage of irradiating high luminance light to the liquid crystal display panel 22. Since the direct type backlight unit is installed under the liquid crystal display panel 22 in a state where the lamps 12 are spaced at predetermined intervals, the brightness of the direct backlight unit is significantly different between the positions of the lamps 12 and the lamps 12. . The diffuser plate 18 uses the distance difference from the lamps 12 and the scattering of light to reduce the bright line appearing between the location of the lamps 12 and the location between the lamps 12. The diffuser plate 18 may not only exhibit bright lines due to the lamps 12, but also may be manufactured in a thick plate shape and may be made of a thin and easily bent material as shown in FIG. 2 by supporting the optical sheets 20 from below. The optical sheets 20 are prevented from being struck by their own weight.

However, since the diffusion plate 18 is thick and has a large weight, the diffusion plate 18 acts as a component that hinders the weight reduction of the liquid crystal display device, and the manufacturing cost of the diffusion plate 18 increases the manufacturing cost of the liquid crystal display device. In addition, the diffusion plate 18 may be convexly curved by heat generation of the lamps 12, and the deformation of the diffusion plate 18 may significantly reduce the plane uniformity of the light incident on the liquid crystal display panel 22 as shown in FIG. 3. It lowers the display quality of a liquid crystal display device.

Accordingly, it is an object of the present invention to provide a backlight unit to prevent sagging of optical sheets without a diffuser plate.

Another object of the present invention is to provide a liquid crystal display device which can be made lighter and thinner by using the backlight unit.

In order to achieve the above object, the backlight unit according to an embodiment of the present invention comprises a plurality of light sources; A bottom cover accommodating the light sources and having an open top surface; A net intersecting an opening surface of the bottom cover at both ends of the bottom of the bottom cover so as to be spaced apart from the light sources above the light sources; And at least one optical sheet disposed on the net.

According to another embodiment of the present invention, a backlight unit includes a plurality of light sources; A bottom cover accommodating the light sources and having an open top surface; A first net fixed at both ends of the bottom sidewalls of the bottom cover so as to be spaced apart from the light sources above the light sources and crossing the opening surface of the bottom cover; A plurality of optical sheets disposed on the net; And a second net forming an air diffusion layer on the surface between the optical sheets across the surface between the optical sheets.

Each of the first and second nets may include: a first support string crossing the opening surface of the bottom cover along a first direction; And a second support string crossing the opening surface of the bottom cover in a second direction crossing the first direction.

Each of the first and second nets has a plurality of support lines that cross the opening surface of the bottom cover side by side in either direction.

Each of the support lines is formed of a transparent or opaque metal or plastic having a thickness between 0.1 mm and 2 mm.

Liquid crystal display device according to an embodiment of the present invention; And a plurality of light sources, a bottom cover in which the light sources are accommodated, and an upper surface of the light source, and both ends of which are fixed to upper ends of sidewalls of the bottom cover so as to be spaced apart from the light sources. And a backlight unit for irradiating light to the liquid crystal display panel, including a net and at least one optical sheet disposed on the net.

According to another exemplary embodiment of the present invention, a liquid crystal display device includes a liquid crystal display panel; And a plurality of light sources, a bottom cover in which the light sources are accommodated, and an upper surface of the bottom cover, wherein both ends are fixed to upper ends of sidewalls of the bottom cover so as to be spaced apart from the light sources above the light sources and cross the opening surface of the bottom cover. 1 net, a plurality of optical sheets disposed on the net, and a second net to form an air diffusion layer on the surfaces between the optical sheets across the surfaces between the optical sheets. And a backlight unit to irradiate.

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

4 to 10, preferred embodiments of the present invention will be described.

4 and 5, the liquid crystal display according to the first exemplary embodiment of the present invention includes a liquid crystal display panel 58 and a plurality of lamps 50 irradiating light under the liquid crystal display panel 58. And a bottom cover 54 accommodating the lamps 50 and having a reflector plate 52 attached to the bottom under the lamps 50, and diffusing light from the lamps 50 or the liquid crystal display panel 58. One or more optical sheets 56 that bend the path of light perpendicular to the display surface of the sensor, and are positioned between the lamps 50 and the optical sheets 56 to support the optical sheets 56. A net is provided. In such a liquid crystal display, a diffusion plate that previously supports optical sheets is removed.

The liquid crystal display panel 58 includes a spacer (not shown) for injecting liquid crystal between the upper substrate and the lower substrate and for maintaining a constant gap between the upper substrate and the lower substrate. A color filter, a common electrode, a black matrix, and the like, which are not shown, are formed on the upper substrate of the liquid crystal display panel 58. In addition, signal lines such as data lines and gate lines (not shown) are formed on the lower substrate of the liquid crystal display panel 58, and thin film transistors (“TFTs” hereinafter) are formed at intersections of the data lines and the gate lines. ) Is formed. The TFT switches the data signal to be transmitted from the data line toward the liquid crystal cell in response to the scan signal (gate pulse) from the gate line. The pixel electrode is formed in the pixel region between the data line and the gate line.

The lamps 50 may be discharge tube lamps such as cold cathode fluorescent lamps (CCFLs) or external electrode fluorescent lamps (EEFLs), or light emitting diodes (LEDs) or the like. It is composed of a combination. To apply a voltage to these lamps 50 both electrodes of the lamps 50 are electrically connected to the inverter via a connector.

The optical sheets 56 include a diffusion sheet for diffusing light incident from the lamps 50 and at least one prism sheet for advancing light in a direction perpendicular to the display surface of the liquid crystal display panel 58.

The net 60 crosses the top opening surface of the bottom cover 54 in a single direction or in several directions, and both ends thereof are fixed to the bottom cover 54. As an example, the net 60 has a first support line 60a which is fixed at both ends to the left and right walls of the bottom cover 54 and is stretched along the transverse direction parallel to the lamps 50 as shown in FIG. 4, Both ends of the upper and lower sidewalls of the bottom cover 54 are fixed to include a second support line 60b that is pulled taut along the longitudinal direction orthogonal to the first support line 60a. That is, the net 60 is spaced apart from the lamps 50 on the lamps 50 in a net structure at predetermined intervals.

The net 60 may be provided with at least one layer so that the thin optical sheets 56 may be stacked without sagging. The net 60 supports the optical sheets 56 from below without affecting the light traveling from the lamps 12 toward the liquid crystal display panel 58 to prevent sagging of the optical sheets 56. Play a role. To this end, each of the support lines 60a and 60b of the net 60 is formed of a transparent or opaque metal or plastic having a thickness of between 0.1 mm and 2 mm.

The liquid crystal display device according to the embodiment of the present invention can reduce the weight and slimness of the liquid crystal display device by removing the conventional diffusion plate and installing the net 60 supporting the optical sheets 56 instead of the diffusion plate. Since there is no thermal deformation of the diffusion plate, it is possible to prevent luminance unevenness due to the deformation of the diffusion plate, thereby increasing the luminance plane uniformity of the display image. In addition, in the liquid crystal display according to the exemplary embodiment of the present invention, manufacturing cost may be reduced by removing a conventional expensive diffusion plate.

The net 60 may be manufactured in various forms as shown in FIGS. 6 to 9.

Referring to FIG. 6, the support lines of the net 70 may be fixed to the bottom cover 54 in a longitudinal direction parallel to the lamp 50, in a longitudinal direction and a diagonal direction crossing the lamp 50.

Referring to FIG. 7, the first support line 72a and the second support line 72b of the net 72 are fixed to four corners of the bottom cover 54, and they intersect at the central portion of the bottom cover 54. do.

Referring to FIG. 8, the net 74 is fixed to the bottom cover 54 only in the transverse direction parallel to the lamp 50.

9, the net 76 is fixed to the bottom cover 54 only in the longitudinal direction orthogonal to the lamp 50.

10 illustrates a liquid crystal display according to another exemplary embodiment of the present invention. In FIG. 10, components substantially the same as those of the above-described embodiments of FIGS. 4 and 5 will be denoted by the same reference numerals and detailed description thereof will be omitted.

Referring to FIG. 10, a liquid crystal display according to an exemplary embodiment of the present invention includes a plurality of lamps 50 arranged in parallel with the liquid crystal display panel 58 and irradiating light to the liquid crystal display panel 58. A bottom cover 54 disposed on the rear surface of the lamps 50 to receive the lamps 50 and to which a reflecting plate 52 is attached to the bottom, and diffuse light from the lamps 50 or to the liquid crystal display panel 58. Optical sheets 56 for advancing light perpendicular to the display surface of the &lt; RTI ID = 0.0 &gt;), &lt; / RTI &gt; and a first net positioned between the lamps 50 and the optical sheets 56 to support the optical sheets 56. 60 and a second net 80 provided between the optical sheets 56.

The second net 80 is installed between the optical sheets 56 to prevent sagging of the optical sheets 56. The second net 80 is located between the optical sheets 56 to secure the space between the optical sheets 56 as the air diffusion layer, thereby increasing the light diffusivity. The second net 80 is made of a mesh structure, the mesh shape can be modified in various forms as shown in Figs. The second net 80 is formed of a string or a narrow support so as not to affect the progress of the light emitted from the lamps 50. To this end, the second net 80 is formed of a transparent or opaque metal or plastic having a thickness of 0.1mm ~ 2mm.

As described above, the backlight unit according to the present invention can prevent the sagging of the optical sheets due to the support of the net by installing a thin, almost occupied net between the lamps and the optical sheets instead of removing the diffuser plate. Of course, there is no degradation of the surface uniformity of light due to the deformation of the diffusion plate. The liquid crystal display device according to the present invention can not only be lightened and thinned by using the backlight unit, but also the surface uniformity of the display image can be improved and the display quality can be improved. Furthermore, the backlight unit and the liquid crystal display device according to the embodiment of the present invention can reduce the manufacturing cost of the expensive diffusion plate in the manufacturing cost, it is possible to reduce the manufacturing cost, it is possible to increase the diffusion of light by forming an air diffusion layer between the optical sheets. .

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the 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 (22)

A plurality of light sources; A bottom cover accommodating the light sources and having an open top surface; A net intersecting an opening surface of the bottom cover at both ends of the bottom of the bottom cover so as to be spaced apart from the light sources above the light sources; And And at least one optical sheet disposed on the net. The method of claim 1, The net, A first support string crossing the opening surface of the bottom cover along a first direction; And a second support string crossing the opening surface of the bottom cover along a second direction crossing the first direction. The method of claim 2, Each of the support lines is a backlight unit, characterized in that formed of a transparent or opaque metal or plastic having a thickness of 0.1mm ~ 2mm. The method of claim 1, The net, And a plurality of support lines crossing the opening surface of the bottom cover side by side in one direction. The method of claim 4, wherein Each of the support lines is a backlight unit, characterized in that formed of a transparent or opaque metal or plastic having a thickness of 0.1mm ~ 2mm. The method of claim 1, The optical sheet, One or more diffusion sheets for diffusing the light; And at least one prism sheet for bending the path of the light. A plurality of light sources; A bottom cover accommodating the light sources and having an open top surface; A first net fixed at both ends of the bottom sidewalls of the bottom cover so as to be spaced apart from the light sources above the light sources and crossing the opening surface of the bottom cover; A plurality of optical sheets disposed on the net; And And a second net for forming an air diffusion layer on a surface between the optical sheets across the surfaces between the optical sheets. The method of claim 7, wherein Each of the first and second nets, A first support string crossing the opening surface of the bottom cover along a first direction; And a second support string crossing the opening surface of the bottom cover along a second direction crossing the first direction. The method of claim 8, Each of the support lines is a backlight unit, characterized in that formed of a transparent or opaque metal or plastic having a thickness of 0.1mm ~ 2mm. The method of claim 7, wherein Each of the first and second nets And a plurality of support lines crossing the opening surface of the bottom cover side by side in one direction. The method of claim 10, Each of the support lines is a backlight unit, characterized in that formed of a transparent or opaque metal or plastic having a thickness of 0.1mm ~ 2mm. A liquid crystal display panel; And A plurality of light sources, a bottom cover in which the light sources are accommodated, and an upper surface of the bottom cover; a net having both ends fixed to upper ends of sidewalls of the bottom cover so as to be spaced apart from the light sources above the light sources; And a backlight unit for irradiating light to the liquid crystal display panel, the backlight unit including one or more optical sheets disposed on the net. The method of claim 12, The net, A first support string crossing the opening surface of the bottom cover along a first direction; And a second support string crossing the opening surface of the bottom cover in a second direction crossing the first direction. The method of claim 13, Wherein each of the support lines is formed of a transparent or opaque metal or plastic having a thickness between 0.1 mm and 2 mm. The method of claim 12, The net, And a plurality of support lines crossing the opening surface of the bottom cover side by side in one direction. The method of claim 15, Wherein each of the support lines is formed of a transparent or opaque metal or plastic having a thickness between 0.1 mm and 2 mm. The method of claim 12, The optical sheet, One or more diffusion sheets for diffusing the light; And at least one prism sheet for bending the traveling path of the light. A liquid crystal display panel; And A plurality of light sources, a bottom cover in which the light sources are received and the top surface is opened, the first end is fixed to the top of the side walls of the bottom cover so as to be spaced apart from the light sources above the light sources to cross the opening surface of the bottom cover A net, a plurality of optical sheets disposed on the net, and a second net which forms an air diffusion layer on the surfaces between the optical sheets across the surfaces between the optical sheets. And a backlight unit. The method of claim 18, Each of the first and second nets, A first support string crossing the opening surface of the bottom cover along a first direction; And a second support string crossing the opening surface of the bottom cover in a second direction crossing the first direction. The method of claim 19, Wherein each of the support lines is formed of a transparent or opaque metal or plastic having a thickness between 0.1 mm and 2 mm. The method of claim 18, Each of the first and second nets And a plurality of support lines crossing the opening surface of the bottom cover side by side in one direction. The method of claim 21, Wherein each of the support lines is formed of a transparent or opaque metal or plastic having a thickness between 0.1 mm and 2 mm.

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