KR20160080857A - Back light unit and liquid crystal display device having the same - Google Patents

Abstract

The present invention provides a backlight unit which comprises: a light source; a plurality of optical sheets installed between the light source and a liquid crystal panel; a light guide plate installed between the light source and the optical sheets to convert light from the light source and irradiate the converted light to the optical sheets; a lower cover installed below the light guide plate; and a light guide plate holder interposed between an edge portion of the light guide plate and an internal edge portion of the lower cover. Therefore, the backlight unit can maintain a gap caused by expansion of the light guide plate even under a high temperature environment.

Description

BACKLIGHT UNIT AND LIQUID CRYSTAL DISPLAY DEVICE HAVING THE SAME [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display, and more particularly, to a backlight unit capable of controlling the flow and expansion of a light guide plate of a backlight unit and a liquid crystal display including the same.

BACKGROUND ART In general, a liquid crystal display (LCD) displays a desired image by adjusting the light transmittance of liquid crystal cells arranged in a matrix according to image signal information. Thereby forming an image on the panel.

The liquid crystal display device using such a principle has a tendency of widening its application range due to features such as light weight, thinness and low power consumption driving. In accordance with this trend, liquid crystal display devices are used in office automation equipment, audio / video equipment, and the like. In such a liquid crystal display device, a light transmission amount is adjusted according to a signal applied to a plurality of control switches arranged in a matrix form to display a desired image on a screen.

2. Description of the Related Art In recent years, liquid crystal display devices have been extensively applied to computer monitors, televisions, display devices of vehicle navigator systems, and portable display devices such as notebook computers and cellular phones.

Since most of the liquid crystal display devices described above are non-emissive type display devices that display an image by adjusting the amount of a light source coming from the outside, a backlight including a separate light source for irradiating light to the liquid crystal display panel We need a unit.

A conventional liquid crystal display device having such a backlight unit will be described with reference to FIGS. 1 to 5. FIG.

1 is a schematic plan view of a liquid crystal display device having a backlight unit according to the related art.

2 is an assembled cross-sectional view of a liquid crystal display device having a backlight unit according to the related art.

Fig. 3 is an enlarged plan view of the "A" portion of Fig. 1, and is a plan view of a liquid crystal display device having a backlight unit according to the related art.

4 is a schematic perspective view of a light guide plate holder of a liquid crystal display device having a backlight unit according to the related art.

5 is a schematic plan view of a liquid crystal display device having a backlight unit according to the related art, in which the light guide plate holder is pushed in a state in which the light guide plate is expanded.

1 and 2, a liquid crystal display device having a backlight unit according to the related art includes a liquid crystal panel 80 in which an image is implemented, a backlight unit (not shown) for supplying light to the liquid crystal panel 80, A panel guide 70 which surrounds and supports the liquid crystal panel 80 and a backlight unit (not shown), and a lower cover 70 which is coupled to the panel guide 70 and accommodates the backlight unit (not shown) 10).

Although not shown in the drawing, the liquid crystal panel 80 includes a color filter array substrate (not shown), a TFT array substrate (not shown), and a liquid crystal layer (not shown) interposed therebetween.

In the liquid crystal panel 80, liquid crystal cells constituting pixel units are arranged in a matrix form, and the liquid crystal cells adjust image transmittance according to image signal information transmitted in a driver driving circuit (not shown) to form an image.

The backlight unit (not shown) includes a light source unit 20 for generating light, a light guide plate 50 for providing light generated from the light source unit 20 to the front surface of the liquid crystal panel 80, A reflective sheet 40 disposed on the back surface of the light guide plate 50 to improve the efficiency of light by reflecting light emitted to the rear side, and a reflective sheet 40 stacked on the entire surface of the light guide plate 50 to scatter light emitted from the light guide plate 50 And a plurality of optical sheets (60).

The light source unit 20 includes a plurality of light emitting devices 21 and a substrate 23 on which the light emitting devices 21 are mounted.

The plurality of optical sheets 60 are configured to diffuse and condense the light incident from the light guide plate 50 and include a diffusion sheet (not shown), a prism sheet (not shown), and a protective sheet (not shown) .

The light guide plate 50 is disposed on one side of the light source unit 20 and disposed on the back surface of the liquid crystal panel 80 so that the light generated from the light source unit 20 is incident on the back surface of the liquid crystal panel 80 .

In addition, the panel guide 70 is formed in a rectangular frame shape that surrounds the side surface of the light guide plate 50, and is formed of a plastic material such as a PC material or a metal material.

The reflective sheet 40 is disposed under the light guide plate 50 and reflects part of the light emitted to the lower portion of the light guide plate 50 to the inside of the light guide plate 50 to increase the light efficiency, So that the entire light emitting surface has a uniform luminance distribution.

The lower cover 10 is in the form of a rectangular box with an open top and includes components such as the optical sheet 60, the light guide plate 50, and the reflective sheet 40, which are wrapped by the panel guide 70 Is housed inside the lower cover (10).

3, a light guide plate holder 30 is disposed on the inner edge of the lower cover 10 so that a side portion of the light guide plate 50 is seated and can be supported without any flow.

4, the LGP holder 30 includes a side portion 31, a resilient supporting portion 33 extending to both sides from the side portion and contacting the side portions of the LGP 50, And a bottom portion 35 on which the lower surface of the base portion 35 is seated. At this time, as shown in FIG. 5, the elastic support portion 33 prevents the light guide plate 50 from flowing while being pressed by the light guide plate when inflated. The light guide plate holder 30 is made of a material having an elastic restoring force, for example, a rubber material.

The lower cover 10 in which the liquid crystal panel 80 and the backlight unit (not shown) are housed is coupled with the panel guide 70 surrounding the liquid crystal panel 80 to form a liquid crystal display (not shown) do.

However, the light guide plate holder of the liquid crystal display device according to the related art has a contradictory relation that the flow gap reduction due to vibration and the light guide plate expansion gap in a high temperature environment must be ensured.

Particularly, in the case of the narrow bezel model, it is difficult to apply the conventional LGP holder in a narrow space.

Therefore, the conventional light guide plate holder merely serves as a guide in assembling, and the flow control for securing the expansion gap of the light guide plate is insufficient.

Further, since the shape of the conventional LGP holder takes up a lot of space, it can be said that it is difficult to apply to a narrow bezel model.

Further, in the case of the conventional light guide plate holder, it is difficult to minimize the size of the holder because the area for dispersing the force of the light guide plate is small in order to secure the flow gap of the light guide plate at two points per unit.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a backlight unit capable of effectively controlling the flow in the X and Y directions even under vibrational shock and ensuring an expansion gap even in a high temperature environment and a liquid crystal display device having the backlight unit.

According to one aspect of the present invention, there is provided a liquid crystal display comprising: a light source; a plurality of optical sheets provided between the light source and the liquid crystal panel; and a plurality of optical sheets provided between the light source and the optical sheets, And a light guide plate holder interposed between an edge portion of the light guide plate and an inner edge portion of the lower cover to provide a backlight unit including the light guide plate, .

In this backlight unit, the light guide plate holder may include a bending support and first and second wave elastic portions extending from both ends of the bending support.

In such a backlight unit, the first and second wave elastic portions of the light guide plate holder may be in contact with both sides of the light guide plate contacting with each other.

According to another aspect of the present invention, there is provided a liquid crystal display comprising: a liquid crystal panel; a light source for providing light to the liquid crystal panel; a plurality of optical sheets provided between the light source and the liquid crystal panel; A light guide plate for converting light from the light source to irradiate the light to the optical sheets, a lower cover provided below the light guide plate, and a light guide plate holder interposed between an edge portion of the light guide plate and an inner corner portion of the lower cover It is possible to provide a liquid crystal display device provided with a unit.

In the liquid crystal display device having such a backlight unit, the light guide plate holder may include a bending support member and first and second wave elastic members extending from both ends of the bending support member.

In the liquid crystal display device having such a backlight unit, the first and second wave elastic portions of the light guide plate holder can be brought into contact with both sides of the light guide plate contacting with each other.

The backlight unit and the liquid crystal display device having the same according to the present invention are provided with a light guide plate holder having a wave elasticity part between the inner edge of the lower cover and the edge of the light guide plate, And the gap due to the expansion of the light guide plate can be maintained under high temperature environment conditions.

In particular, the light guide plate holder can effectively control the flow in both the X and Y directions on both sides of the light guide plate contacting with each other by the wave elastic portions provided at both ends of the bending support, .

Since the light guide plate holder of the present invention easily assemble the light guide plate to the inner edge portion of the lower cover through the wave elastic portions provided at both ends of the bending support plate, it is possible to prevent the flow and secure the expansion gap, It can be effectively applied.

1 is a schematic plan view of a liquid crystal display device having a backlight unit according to the related art.
2 is an assembled cross-sectional view of a liquid crystal display device having a backlight unit according to the related art.
Fig. 3 is an enlarged plan view of the "A" portion of Fig. 1, and is a plan view of a liquid crystal display device having a backlight unit according to the related art.
4 is a schematic perspective view of a light guide plate holder of a liquid crystal display device having a backlight unit according to the related art.
5 is a schematic plan view of a liquid crystal display device having a backlight unit according to the related art, in which the light guide plate holder is pushed in a state in which the light guide plate is expanded.
6 is an exploded perspective view of a liquid crystal display device having a backlight unit according to the present invention.
7 is a schematic plan view of a liquid crystal display device having a backlight unit according to the present invention, and is a plan view schematically showing a state in which a light guide plate holder is inserted between a light guide plate and a lower cover.
FIG. 8 is an enlarged plan view of a light guide plate holder inserted between a light guide plate and a lower cover of a liquid crystal display device having a backlight unit according to the present invention.
9 is an assembled cross-sectional view of a liquid crystal display device having a backlight unit according to the present invention.
10 is a schematic perspective view of a light guide plate holder of a liquid crystal display device having a backlight unit according to the present invention.
11 is a schematic enlarged plan view of a liquid crystal display device having a backlight unit according to the present invention, and is a plan view schematically showing a state in which a wave elastic part of a light guide plate holder in a state in which a light guide plate is expanded is pressed.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. It should be noted that, in adding reference numerals to the constituent elements of the drawings, the same constituent elements are denoted by the same reference numerals whenever possible, even if they are shown in different drawings. In the following description of the embodiments of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

In describing the components of the invention, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are intended to distinguish the constituent elements from other constituent elements, and the terms do not limit the nature, order or order of the constituent elements. When a component is described as being "connected", "coupled", or "connected" to another component, the component may be directly connected to or connected to the other component, It should be understood that an element may be "connected," "coupled," or "connected." In the same context, when an element is described as being formed on an "upper" or "lower" side of another element, the element may be formed either directly or indirectly through another element As will be understood by those skilled in the art.

6 is an exploded perspective view of a liquid crystal display device having a backlight unit according to the present invention.

7 is a schematic plan view of a liquid crystal display device having a backlight unit according to the present invention, and is a plan view schematically showing a state in which a light guide plate holder is inserted between a light guide plate and a lower cover.

FIG. 8 is an enlarged plan view of a light guide plate holder inserted between a light guide plate and a lower cover of a liquid crystal display device having a backlight unit according to the present invention.

9 is an assembled cross-sectional view of a liquid crystal display device having a backlight unit according to the present invention.

6, a liquid crystal display 100 according to the present invention includes a liquid crystal panel 180, a backlight unit (not shown) for supplying light to the liquid crystal panel 180, A panel guide 170 that surrounds the backlight unit 180 and a backlight unit (not shown), and a lower cover 110 that is coupled to the panel guide 170 and accommodates the backlight unit.

Although not shown in the figure, the liquid crystal panel 180 includes a color filter array substrate (not shown), a TFT array substrate (not shown), and a liquid crystal layer (not shown) interposed therebetween. Although not shown in the figure, the liquid crystal panel 180 is a front polarizing plate (not shown) attached to the front surface of the color filter array substrate and the back surface of the TFT array substrate so that light transmitted through the liquid crystal panel 180 is cross- And a rear polarizer (not shown).

In this liquid crystal panel 180, liquid crystal cells constituting pixel units are arranged in a matrix form, and the liquid crystal cells adjust the light transmittance according to the image signal information transmitted from the driver driving circuit 183 to form an image.

A plurality of gate lines and a plurality of data lines are formed in a matrix form in the TFT array substrate (not shown). Thin film transistors (TFTs) are formed at intersections of the gate lines and the data lines, Is formed. The signal voltage transferred from the driver driving circuit 183 is applied between the pixel electrode and a common electrode (not shown) of a color filter array substrate (not shown) to be described later, and the liquid crystal between the pixel electrode and the common electrode And the light transmittance is determined according to the signal voltage.

Although not shown in the figure, the color filter array substrate (not shown) includes a color filter and a common electrode in which red, green, and blue or cyan, magenta, and yellow are repeatedly formed with a black matrix as a boundary. The common electrode is made of a transparent conductive material such as ITO (Indium Tin Oxide) or IZO (Indium Zinc Oxide).

A driving driver 183 for driving unit pixels formed on the liquid crystal panel and a flexible printed circuit board (FPCB) 185 connected at one end to the liquid crystal panel are formed on one side of the liquid crystal panel 180 ).

The backlight unit (not shown) includes a light source 120 for generating light, a light guide plate 140 for providing light generated from the light source 120 to the front surface of the liquid crystal panel 180, And a plurality of optical sheets 140 stacked on the entire surface of the light guide plate 140 and scattering light emitted from the light guide plate 140. [ (160).

Here, the light source unit 120 may be a cold cathode fluorescent lamp (CCFL), an external electrode fluorescent lamp (EEFL), or a light emitting diode (LED) Here, the case of applying a light emitting diode element (light emitting element) is taken as an example. The light source unit 120 includes a light emitting device 121 and a printed circuit board 123 on which the light emitting device 121 is mounted. The light emitting device 121 is a side viewing type device and the light emitting device 121 outputs light toward the light incident surface (not shown) of the light guide plate 140.

The printed circuit board 123 is a flexible circuit board having excellent warpage, and a circuit (not shown) is formed therein to supply external power to the light emitting device 121 through the circuit.

The plurality of optical sheets 160 are for diffusing and condensing the light incident from the light guide plate 160. Although not shown in the figure, the optical sheets 160 may include a diffusion sheet (not shown), a prism sheet (not shown) (Not shown). In some cases, it may be provided with two diffusion sheets and two prism sheets. At this time, the diffusion sheet is composed of a base plate and a bead coating layer formed on the base plate. The diffusion sheet diffuses the light from the light source 120 and supplies the light to the liquid crystal panel 180. Two or three sheets of the diffusion sheet may be used in a superimposed manner. The prism sheet (not shown) has a triangular columnar prism formed on the upper surface thereof with a predetermined arrangement. The prism sheet (not shown) condenses light diffused in the diffusion sheet in a direction perpendicular to the plane of the upper liquid crystal panel 180. Normally, two prism sheets (not shown) are used, and a micro prism formed on each prism sheet (not shown) has a predetermined angle.

Accordingly, most of the light passing through the prism sheet proceeds vertically to provide a uniform luminance distribution. A protective sheet (not shown) located at the uppermost position protects the prism sheet (not shown), which is vulnerable to scratches.

The light guide plate 140 includes a light incidence surface (not shown) on which light is incident from the light emitting device 121, a light exit surface (not shown) extending from the light incidence surface and facing the liquid crystal panel 180, And a back surface on which a dot pattern (not shown) is formed such that light emitted from the light emitting device 121 to the light-entering surface progresses to the light-emitting surface.

The light guide plate 140 is disposed on one side of the light emitting device 121 and disposed on the back surface of the liquid crystal panel 180 so that the light generated from the light emitting device 121 is incident on the back surface of the liquid crystal panel 180 . The light guide plate 140 converts the light emitted from the light emitting device 121 disposed adjacent to one side of the light guide plate 140, that is, the light incident surface, into a plane light and transmits the light to the liquid crystal panel 180 And uniformly transmitted.

As the material of the light guide plate 140, a PMMA (polymethyl methacrylate) having a high strength and a good transmittance without being easily deformed or broken can be used. The light guide plate 140 may be a wedge having a lower surface inclined and a flat upper surface, or a plate type having a lower surface and an upper surface parallel to each other.

In the case of a liquid crystal display device applied to a small-sized product such as a notebook PC or a mobile phone, a wedge-shaped light guide plate 140 may be used, and the light source 140 may be provided on the thick side wall.

The panel guide 170 is formed in a rectangular frame that surrounds the side surface of the light guide plate 140 and is formed of a plastic material such as a PC material or a metal material. At this time, the panel guide 170 also functions to cover the optical sheet 160 and the light guide plate 140, in addition to supporting the liquid crystal panel 180.

The reflective sheet 130 is disposed below the light guide plate 140 and reflects a part of the light emitted to the lower portion of the light guide plate 140 to the inside of the light guide plate 140 to increase the light efficiency, So that the entire light emitting surface has a uniform luminance distribution.

The lower cover 110 includes a light guide plate 140 wrapped by the panel guide 170 and a backlight unit including an optical sheet 160 and a reflective sheet 130, Time components are housed.

10 is a schematic perspective view of a light guide plate holder of a liquid crystal display device having a backlight unit according to the present invention.

10, a light guide plate holder 150 is inserted between the inner side edge of the lower cover 110 and the outer side edge of the light guide plate so that the flow of the light guide plate 140, that is, , And controls the flow and expansion in the rightward direction, that is, in the X and Y directions. The light guide plate holder 150 includes a bending support 151 and first and second wave elastic members 153 extending from both ends of the bending support 151. The first and second wave elastic portions 153 of the light guide plate holder 150 are in contact with the inner edge portions of the lower cover 110 in a state of being in contact with both side portions which are in contact with the respective corner portions of the light guide plate 140, Respectively.

Accordingly, since the light guide plate holder of the present invention can easily prevent the flow and secure the expansion gap by simply assembling the light guide plate to the inner edge portion of the lower cover through the wave elastic portions provided at both ends of the bending support, the narrow bezel model It can be effectively applied.

11 is a schematic enlarged plan view of a liquid crystal display device having a backlight unit according to the present invention, and is a plan view schematically showing a state in which a wave elastic part of a light guide plate holder in a state in which a light guide plate is expanded is pressed.

As shown in FIG. 11, the first and second wave elastic portions 153 are pressed when the light guide plate 140a expands under high-temperature environmental conditions, thereby securing a constant expansion gap. That is, when the light guide plate 140a is expanded in one direction under a high-temperature environmental condition, the first and second wave elastic force portions 153 of the light guide plate holder 150 are pressed and stretched to the left and right sides, , The wave form of the two-wave elastic part 153 is released and its width is narrowed, so that a constant gap with respect to the expansion of the light guide plate 140 is secured.

Accordingly, the light guide plate 140 is more tightly adhered to the side edge portions of the lower cover 110, thereby preventing the light guide plate 140 from flowing. In this case, the light guide plate holder 150 including the first and second wave elastic force parts 153 is made of a rubber material or a plastic material having elasticity, but it is not limited thereto, .

The light guide plate holder 150 is sandwiched between the inner side edge of the lower cover 110 and the outer side edge of the light guide plate in a state in which the light guide plate 140 is disposed inside the lower cover 110 And then the light guide plate 140 is assembled into the lower cover 110 by applying a predetermined pressure.

As described above, the backlight unit and the liquid crystal display device having the same according to the present invention include the light guide plate holder having the wave elasticity portion in the bending support between the inner edge of the lower cover and the edge portion of the light guide plate, The flow gap can be reduced to prevent the gap, and the gap due to the expansion of the light guide plate can be maintained under the high temperature environment.

Particularly, the light guide plate holder can effectively control the flow in the upper, lower, left and right directions, that is, the X and Y directions, both sides of the light guide plate contacting with each other by the wave elastic portions provided at both ends of the bending support And the expansion gap of the light guide plate can be secured even in a high temperature environment.

Since the light guide plate holder of the present invention easily assemble the light guide plate to the inner edge portion of the lower cover through the wave elastic portions provided at both ends of the bending support plate, it is possible to prevent the flow and secure the expansion gap, It can be effectively applied.

Although the embodiments have been described with reference to the drawings, the present invention is not limited thereto.

It is to be understood that the terms "comprises", "comprising", or "having" as used in the foregoing description mean that the constituent element can be implanted unless specifically stated to the contrary, But should be construed as further including other elements. All terms, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, unless otherwise defined. Commonly used terms, such as predefined terms, should be interpreted to be consistent with the contextual meanings of the related art, and are not to be construed as ideal or overly formal, unless expressly defined to the contrary.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

100: liquid crystal display device 110: lower cover
140: light guide plate 150: light guide plate holder
151: bending support 153: wave elastic part

Claims (6)

Light source;
A plurality of optical sheets provided between the light source and the liquid crystal panel;
A light guide plate provided between the light source and the optical sheets to convert light from the light source and irradiate the light onto the optical sheets;
A lower cover provided below the light guide plate; And
And a light guide plate holder interposed between an edge of the light guide plate and an inner edge of the lower cover. The backlight unit according to claim 1, wherein the light guide plate holder includes a bending support and first and second wave elastic portions extending from both ends of the bending support. The backlight unit according to claim 1, wherein the first and second wave elastic portions of the light guide plate holder are in contact with both side surfaces of the light guide plate contacting with each other. A liquid crystal panel;
A light source for providing light to the liquid crystal panel;
A plurality of optical sheets provided between the light source and the liquid crystal panel;
A light guide plate provided between the light source and the optical sheets to convert light from the light source and irradiate the light onto the optical sheets;
A lower cover provided below the light guide plate; And
And a backlight unit including a light guide plate holder interposed between an edge of the light guide plate and an inner edge of the lower cover. The liquid crystal display device according to claim 4, wherein the light guide plate holder includes a bending support and a backlight unit including first and second wave elastic portions extended from both ends of the bending support. The liquid crystal display of claim 4, wherein the first and second wave elastic portions of the light guide plate holder are in contact with both side surfaces of the light guide plate adjacent to each other.

Images