KR20090003759A - Light guide plate, back light unit therewith and liquid crystal display device - Google Patents

Abstract

A backlight unit according to an embodiment of the present invention, a case; A light source for generating light; And a light guide plate disposed on the case, the light guide plate having a light incident surface on which light generated by the light source is incident on one side thereof, and at least one diffused lens disposed on the light incident surface of the light guide plate to correspond to the light source.

Description

Light guide plate, backlight unit having same, and liquid crystal display device having same {Light guide plate, back light unit therewith and liquid crystal display device}

The present invention relates to a light guide plate, a backlight unit having the same, and a liquid crystal display device having the backlight unit. In detail, an inclined surface is formed on at least one side of the side ends to change the optical path to extend the optical path. A light guide plate having a furnace extension, a backlight unit having such a light guide plate, and a liquid crystal display device having the backlight unit are provided.

BACKGROUND ART As a backlight unit for illumination of a display panel such as a liquid crystal panel, an LED backlight unit using an LED (light emitting diode) is known. The LED backlight unit uses three types of LEDs that generate monochromatic light of red (R), green (G), and blue (B) as a set to produce white light by mixing monochromatic light emitted from each LED. There is a type (hereinafter, referred to as "RGB-LED backlight unit").

Since the RGB-LED backlight unit is a principle of mixing three types of monochromatic light and obtaining white light, it is necessary to secure a mixing distance of a predetermined length to the light incident surface layer of the LED of the monochromatic light source in order to mix monochromatic light.

In the case of a general RGB-LED backlight unit, the LED is placed on the side of the light incident surface of the light guide plate and arranged so that the light from the LED is incident on the end face of the light guide plate, and the high power LED is arranged and diffused below the diffuser plate. And a direct method of diffusing light in the vertical direction by the plate.

However, in order to secure the mixing distance, the edge light method increases the size of the backlight unit in order to arrange the LED light source outward from the edge of the light guide plate or to increase the mixing distance in the light guide plate, and the light does not reach the center of the display device sufficiently. However, there are problems that are not suitable for relatively large displays. In addition, in the direct method, in order to secure a mixing distance, the LED light source has to be spaced apart from the diffusion plate and the like, and as a result, the thickness of the backlight unit becomes thick.

1 and 2 are schematic exploded perspective views of a general edge type LED backlight unit and a plan view showing a path of light from the LED to the light guide plate in the case of such a general edge type LED backlight unit.

As such a general RGB-LED backlight unit, the light guide plate 2 is disposed inside the case 5, and a plurality of high-performance LEDs 6R, 6G, and 6B arranged at regular intervals on the metal PCB 7 are disposed in the light guide plate ( It is a structure arranged to face the light-receiving part arranged in the side end part of 2). Each light generated in the plurality of LED assemblies 6R, 6G, 6B mounted on the metal PCB 7 is developed at a predetermined angle a and enters the light guide plate to proceed. In this case, a dark portion appears in a section B in which light generated by an arbitrary LED assembly is not mixed with light generated by an adjacent LED assembly, and in an LED assembly that generates three colors, that is, red, green, and blue light, respectively. The distance L of the section where the light is completely mixed becomes long. Therefore, there is a problem in that the side size of the backlight unit becomes larger as the mixing distance of the light becomes longer.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a light guide plate that can generate high quality light by sufficiently mixing the light generated by the individual LED light sources while making it compact without increasing the size of the backlight unit. A backlight unit having a light guide plate and a liquid crystal display device are provided.

A backlight unit according to an embodiment of the present invention for achieving the above object, a case; A light source for generating light; And a light guide plate disposed on the case, the light guide plate having a light incident surface on which light generated by the light source is incident on one side thereof, and at least one diffused lens disposed on the light incident surface of the light guide plate to correspond to the light source.

Here, the light source is a plurality of LED assemblies.

On the other hand, a plurality of the LED assembly generates red, green, blue light respectively.

Optionally, a plurality of said LED assemblies generate white light.

On the other hand, the diffusion lens is a concave lens formed concave on the light incident surface of the light guide plate.

In particular, the inner side of the concave lens is an elliptical pillar shape.

On the other hand, the upper member and the lower member for closing the upper end and the lower end of the concave lens may be further provided.

In addition, the light source is disposed outside the diffusion lens.

Optionally, the light source may be disposed inside the diffusion lens.

Meanwhile, the light guide plate according to the embodiment of the present invention is a light guide plate having a light incident surface on which light is incident on at least one side of the side ends, and includes one or more diffused lenses disposed on the light incident surface of the light guide plate.

Here, the diffusion lens is a concave lens formed concave on the light incident surface of the light guide plate.

In addition, the inner side of the concave lens is an elliptical pillar shape.

In addition, the upper member and the lower member for closing the upper end and the lower end of the concave lens is further provided.

A liquid crystal display according to an embodiment of the present invention, a case; A light source for generating light; A light guide plate disposed in the case and having a light incident surface on which one side of the light generated by the light source is incident; And a liquid crystal panel disposed on an upper side of the light guide plate to display a screen, wherein one or more diffusion lenses are formed on the light incident surface of the light guide plate to correspond to the light source.

According to the backlight unit, the light guide plate, and the liquid crystal display device according to the present invention, the mixing distance of the light generated from the LED assembly is shortened, so that the size of the backlight unit or the liquid crystal display device can be kept compact. In addition, it is possible to prevent bright lines or dark lines while maintaining the size of the backlight unit and the liquid crystal display device having a compact size. In addition, high quality light uniformity can be achieved while constructing the device in a compact size.

On the other hand, by forming the diffusing lens as a concave lens, it is possible to engraved the light guide plate, thereby making it easy to manufacture the diffusing lens and to prevent interference with other components. In addition, the light guide plate according to the present invention has an effect of reducing the cost by using less light guide plate material.

Hereinafter, with reference to the accompanying drawings will be described in more detail the LED backlight unit according to a preferred embodiment of the present invention.

3 is a partially exploded perspective view of a liquid crystal display device having a liquid crystal panel mounted on an edge type backlight unit according to the present invention, FIG. 4 is a schematic plan view of the backlight unit shown in FIG. 3, and FIG. 5 is a light guide plate according to the present invention. Perspective view.

Referring to FIG. 3, the liquid crystal display device 100 includes a light guide plate 120 disposed to face the rear surface of the liquid crystal panel 110, and an optical sheet interposed between the liquid crystal panel 110 and the light guide plate 120. 3), a light source unit disposed on the side of the light guide plate 120, and a case 150 surrounding the light guide plate.

The light guide plate 120 is preferably formed of a synthetic resin having a light transmitting property. Meanwhile, as shown in FIG. 3, the case 150 and the light guide plate 120 mounted inside the case 150 may be edge type in which the thickness thereof gradually decreases toward the other end face facing the one end face. have. Although not shown, a plurality of patterns may be formed on the rear surface of the light guide plate 120 to diffuse the emitted light. However, the structure of the light guide plate of the present invention is not necessarily limited to the edge type and may be a light guide plate having a uniform thickness. In addition, the backlight unit according to the present invention is not limited to a light source disposed only on one side of the light guide plate, and includes a case where the light source is disposed on a plurality of side surfaces of the light guide plate.

One side of the case 150 is open so that one side of the light guide plate 120 mounted in the case 150 is derived through the one side. The exposed side of the light guide plate becomes a light incident surface 121 (see FIGS. 6 and 7) through which light is incident.

The upper surface of the light guide plate is an emission surface from which light is emitted and the optical sheet 130 is disposed on the front surface of the light emitting plate, and the liquid crystal panel 110 is disposed in close contact with the front surface of the optical sheet 130.

The light source unit includes a plurality of LED assemblies 160R, 160G, and 160B on a metal plate 170 having a thin plate shape, and the LED assemblies are disposed at regular intervals from each other. Although only five LED assemblies are shown in FIGS. 3-7, this is exemplary and the number of LED assemblies can be adjusted as needed. As shown in FIG. 4, a plurality of diffusion lenses 190 are formed on one side of the light guide plate 120 exposed to the side surface of the case 150. The diffusion lens 190 is disposed corresponding to the LED assembly 160R, 160G, 160B.

Here, the LED assembly 160R, 160G, 160B is disposed outside the diffusion lens 190. However, although not shown, the LED assembly 160R, 160G, 160B may be disposed inside the diffusion lens 190 and surrounded by an inner surface of the diffusion lens.

4 and 5, one or more diffusion lenses 190 formed on one side of the light guide plate 120, that is, the light incident surface, are formed in a concave lens shape formed on the light incident surface of the light guide plate. In addition, the inner side of the concave lens is an elliptical pillar shape. More specifically, the inner side surface of the concave lens is preferably a shape corresponding to half of the elliptical pillar shape when viewed from the image side. Here, the ratio of the length of the long axis and the short axis of the ellipse may be variously adjusted.

Meanwhile, an upper end portion and a lower end portion of the diffusion lens 190 having a concave lens shape may have an open structure. Optionally, as shown in FIG. 5, upper and lower members 190b and lower members 190a closing the upper and lower ends are formed at upper and lower ends of the diffusion lens 190 which are concave lenses. Here, the upper member and the lower member are integrally formed of the same material as the material of the light guide plate 120.

Meanwhile, the LED assemblies are R, G, and B LED assemblies 160R, 160G, and 160B respectively forming red, green, and blue. However, the color of the LED assembly is not limited thereto, and may be, for example, an LED assembly in which each LED assembly itself forms white light.

6 is a schematic enlarged plan view illustrating a path in which light of the LED assembly proceeds in the light guide plate of the backlight unit according to the present invention, and FIG. 7 is mixed while the light of the LED assembly proceeds in the light guide plate of the backlight unit according to the present invention. A schematic plan view illustrating the route.

Referring to FIG. 6, for example, the LED assembly 160R forming a red color among the LED assemblies may include an LED chip R emitting red light on a base 162, and the LED chip R may cover an LED cover. It is a structure covered by 164. The LED assembly 160R is disposed corresponding to the diffusion lens 190 formed on the light incident surface 121 of the light guide plate 120. In addition, the LED assembly 160R is in close contact with the light incident surface 121 of the light guide plate. Optionally, the LED assembly 160R may be spaced apart from the light incident surface 121 by a predetermined distance.

Meanwhile, as shown in FIG. 6, the light generated by the LED assembly 160R passes through a space formed by the inner curved surface of the diffusion lens 190 and enters the surface of the diffusion lens 190. At this time, in the space, the light develops while maintaining the angle x, but the light passes through the surface of the diffusion lens 190 and is larger than the angle x due to the difference in refractive index between the space and the light guide plate material. It will be developed at the angle of y. That is, as the light passes through the surface of the diffusion lens 190, the angle of light becomes larger so that the light is dispersed in the lateral direction. For example, although the angle x of light in space is about 60 degrees, the angle y of light increases about 120 degrees while passing through the diffusion lens 190.

When the light diffusion phenomenon in the individual LED assembly is observed for the entire backlight unit, the light proceeds as shown in FIG. 7.

Referring to FIG. 7, the light formed in the individual LED assemblies 160R, 160G, and 160B is diffused at larger angles and proceeds to the inside of the light guide plate 120. Therefore, the light is distributed laterally based on the traveling direction so that the area of overlapping portions (shown as diagonal lines in FIG. 7) between adjacent light traveling paths becomes smaller than the backlight unit of the general case shown in FIG. The dark section is reduced so that the bright line in the vicinity of the light source is reduced.

In addition, since the traveling path of the light passing through the diffusion lens 190 is further dispersed in the lateral direction, the adjacent light and the traveling path overlap earlier, so that the mixing distance l of the light is the backlight in the general case shown in FIG. 2. This is much smaller than the mixing distance L of the unit.

In the case of the backlight unit having the diffusing lens 190 according to the exemplary embodiment of the present invention, the mixing distance is shortened by about 70% or more compared with the conventional case without the diffusing lens.

Therefore, according to the light guide plate, the backlight unit, and the liquid crystal display device according to the present invention, the device itself can be configured more compactly.

The present invention can be used in the field of planar light sources, in particular in the field of technology requiring a backlight as the back lighting.

Although the present invention has been described with reference to the embodiments shown in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

1 is a partially exploded perspective view of a liquid crystal panel mounted on a general edge type backlight unit.

FIG. 2 is a plan view schematically illustrating a path in which light travels from each LED to the light guide plate in the general edge type backlight unit illustrated in FIG. 1.

3 is a partially exploded perspective view of a structure in which a liquid crystal panel is mounted on an edge type backlight unit according to the present invention.

4 is a schematic plan view of the backlight unit illustrated in FIG. 3.

5 is a perspective view of a light guide plate according to the present invention.

FIG. 6 is a schematic enlarged plan view illustrating a path in which light of the LED assembly travels in the light guide plate of the backlight unit according to the present invention. FIG.

FIG. 7 is a schematic plan view illustrating a path in which light of the LED assembly is mixed while traveling in the light guide plate of the backlight unit according to the present invention.

<Description of the symbols for the main parts of the drawings>

100: liquid crystal display 110: liquid crystal panel

120: light guide plate 130: optical sheet

150: case 160R, 160G, 160B: LED assembly

162: base 164: LED cover

190: diffused lens 121: light incident surface

Claims (14)

A case; A light source for generating light; A light guide plate disposed in the case and having a light incident surface on which one side of the light generated by the light source is incident; And at least one diffuser lens disposed on the light incident surface of the light guide plate to correspond to the light source. The method of claim 1, The light source is a backlight unit, characterized in that a plurality of LED assemblies. The method of claim 2, A plurality of the LED assembly is a backlight unit, characterized in that for generating red, green, blue light respectively. The method of claim 2 And a plurality of said LED assemblies generate white light. The method of claim 1, And the diffusion lens is a concave lens formed concave on a light incident surface of the light guide plate. The method of claim 5, wherein And an inner side surface of the concave lens has an elliptic pillar shape. The method of claim 6, And an upper member and a lower member for closing the upper end and the lower end of the concave lens. The method of claim 1, And the light source is disposed outside the diffusion lens. The method of claim 1, And the light source is disposed inside the diffusion lens. A light guide plate having a light incident surface on which light is incident on at least one side of the side ends, A light guide plate comprising one or more diffusion lenses disposed on the light incident surface of the light guide plate. The method of claim 10, The diffusing lens is a light guide plate, characterized in that the concave lens formed concave on the light incident surface of the light guide plate. The method of claim 11, The inner side surface of the concave lens is an light guide plate, characterized in that the elliptical column shape. The method of claim 12, And an upper member and a lower member for closing the upper end and the lower end of the concave lens. A case; A light source for generating light; A light guide plate disposed in the case and having a light incident surface on which one side of the light generated by the light source is incident; A liquid crystal panel disposed on an upper side of the light guide plate to display a screen; And at least one diffusion lens disposed on the light incident surface of the light guide plate to correspond to the light source.

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