KR20110123183A - Backlight unit and liquid crystal display device having the same - Google Patents

Abstract

PURPOSE: A backlight unit and liquid crystal display apparatus are provided to improve the reliability of product by preventing faulty products which are created by a light diffusion pattern. CONSTITUTION: A light source(170b) generates light. A light guide plate(150) includes a light reception unit. The light reception unit receives light which is generated from the light source. A reflection board(180) is located at the bottom of the light guide board. The light guide board reflects the light received in the light guide plate to the bottom of the light guide plate. An adhesion pattern(200) is attached at the light guide board and the reflection board.

Description

Backlight unit and liquid crystal display device having the same {Backlight Unit and Liquid crystal display device having the same}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight unit, and more particularly, to a backlight unit and a liquid crystal display device having the same, which can be easily manufactured and reduce manufacturing costs.

Recently, an information processing device has various forms and various functions, and processes information at a higher speed. The information processed in the information processing apparatus has an electrical signal format. Therefore, in order for the user to visually check the information processed by the information processing apparatus, display apparatuses displaying the information as an image are required.

One of the display devices, a liquid crystal display device, displays an image using liquid crystal. The liquid crystal display device has advantages of thinner, lighter weight, lower power consumption, and lower driving voltage than other display devices.

The liquid crystal display generally includes a liquid crystal display panel that displays an image using a light transmittance of a liquid crystal, and a backlight unit (BLU) disposed on a rear surface of the liquid crystal display panel to provide light to the liquid crystal display panel. Include. In this case, the backlight unit includes a direct type backlight unit and an edge type backlight unit.

The direct type backlight unit includes a plurality of light sources disposed in parallel below the liquid crystal display panel, and directly radiates the light generated from the light sources to the liquid crystal display panel.

On the other hand, the edge type backlight unit includes a light source for generating light, a light guide plate disposed to face side surfaces of the light source, and a light guide plate guiding the light generated by the light source to an upper portion, and a lower portion of the light in the light guide plate. And a reflecting plate for reflecting light directed toward the liquid crystal display panel.

The light guide plate receives light emitted from the light source using a transparent polycarbonate (PC) or acrylic panel, and uniformly distributes the light over the entire area through a pattern having a predetermined area and shape deposited on the acrylic surface. Play a role. The reflective plate reflects the light exiting from the lower portion of the light guide plate and returns the light to the light guide plate.

Light scattering patterns of various shapes, such as hemispherical, square, triangular and hexagonal, are formed on the lower surface of the light guide plate. The light scattering pattern is formed by a printing method using a mask on which a light scattering pattern is formed using a separate ink, injection molding using a patterned mold, or heating using a stamp mold having a light scattering pattern pattern. It is possible to use a variety of methods, such as by manufacturing a product by using a mold, marking the laser beam oscillated from the laser device on the light guide plate, or forming the light guide pattern portion using ultrasonic waves.

On the other hand, the method using a laser of the light scattering pattern forming method has a long processing time, yield reduction and mass production quality deterioration, it is difficult to secure the light scattering pattern shape reproducibility. In addition, the injection molding method has a disadvantage in that it is difficult to mold the mold due to the precision of machining and the injection difficulty is high, resulting in lowered yield, lowered mass production quality, and limited to small and medium models. Printing methods have the disadvantages of light efficiency limitations due to absorption, complexity of the manufacturing process and light scattering patterns in high temperature driving.

Therefore, when the light scattering pattern is formed on the lower part of the light guide plate using this method, the cost increases, and the reliability deterioration such as the mass production quality decreases.

According to the present invention, a pressure-sensitive adhesive pattern is applied to a reflective plate disposed under the light guide plate to meet predetermined conditions, thereby destroying total reflection conditions of the light guide plate, thereby irradiating uniform light onto the liquid crystal display panel without forming a light scattering pattern under the light guide plate. It is an object of the present invention to provide a unit and a liquid crystal display device having the same.

In addition, the present invention provides a backlight unit and a liquid crystal display device having the same, which does not form a light scattering pattern on a light guide plate, thereby reducing a process of manufacturing the light scattering pattern and reducing a manufacturing cost according to the light scattering pattern. Has its purpose.

In addition, an object of the present invention is to provide a backlight unit and a liquid crystal display device having the same, which may improve reliability of a product by preventing a light scattering pattern from forming a light scattering pattern on the light guide plate.

According to an embodiment of the present invention, a backlight unit includes a light guide plate including a light source for generating light, a light incident part through which light generated from the light source is incident, and a lower part of the light guide plate, which is positioned below the light guide plate and is incident on the light guide plate. And a plurality of adhesive patterns applied to the light guide plate and the reflective plate to reflect the light emitted from the light guide plate, and the light guide plate and the reflective plate are attached at a predetermined interval, wherein the plurality of adhesive patterns have a refractive index similar to that of the light guide plate. It consists of.

An LCD according to an exemplary embodiment of the present invention includes a liquid crystal display panel for displaying an image, a light source for irradiating light to the liquid crystal display panel, a light guide plate including a light incident part to which light generated from the light source is incident, and And a plurality of adhesive patterns disposed below the light guide plate to reflect light emitted from the light guide plate to the bottom of the light guide plate, and a plurality of adhesive patterns applied on the reflective plate at specific intervals to attach the light guide plate and the reflective plate. The adhesive pattern of is made of a light transmitting polymer adhesive material having a refractive index similar to that of the light guide plate.

The backlight unit and the liquid crystal display having the same according to the present invention apply an adhesive pattern having a refractive index similar to the refractive index of the light guide plate to a predetermined condition on a reflective plate disposed below the light guide plate, and attach the light guide plate and the reflective plate through the adhesive pattern. By using the pressure-sensitive adhesive, the light generated from the light source can be uniformly irradiated onto the liquid crystal display panel.

In addition, the backlight unit and the liquid crystal display having the same according to the present invention can simplify the manufacturing process by eliminating the process of forming the light scattering pattern by not forming the light scattering pattern on the light guide plate, and reduce the manufacturing cost according to the light scattering pattern. Can be saved.

In addition, the backlight unit and the liquid crystal display device having the same according to the present invention do not form a light scattering pattern on the light guide plate, thereby preventing defects due to the light scattering pattern, thereby improving the reliability of the product.

1 is an exploded perspective view illustrating a liquid crystal display according to an exemplary embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along the line II ′ of FIG. 1.
3 is a plan view illustrating a pressure-sensitive adhesive pattern applied on the reflector of FIG. 2 according to the first embodiment.
4 is a plan view illustrating a pressure-sensitive adhesive pattern applied on the reflector of FIG. 2 according to the second embodiment.
FIG. 5 is experimental data comparing luminance of a liquid crystal display including a pressure-sensitive adhesive pattern and a conventional liquid crystal display having a light scattering pattern formed on a light guide plate by using a printing and laser method.

Hereinafter, embodiments according to the present invention will be described with reference to the accompanying drawings.

1 is an exploded perspective view illustrating a liquid crystal display according to an exemplary embodiment of the present invention.

As shown in FIG. 1, a liquid crystal display according to an exemplary embodiment of the present invention includes a liquid crystal display panel 100 displaying an image and a backlight unit providing light to the liquid crystal display panel 100 displaying the image. 130 and a top case 190 for fixing the liquid crystal display panel 100 to the backlight unit 130.

The liquid crystal display panel 100 is positioned above the backlight unit 130 and displays an image by using light supplied from the backlight unit 130. The liquid crystal display panel 100 is electrically connected to the gate driver 110 and the data driver 120 attached to one side and the other side.

The liquid crystal display panel 100 may include a first substrate 101, a second substrate 103 coupled to the first substrate 101, and a liquid crystal layer formed between the two substrates 101 and 103. Not).

The first substrate 101 includes a plurality of pixels in a matrix form, and each of the plurality of pixels is insulated from a gate line extending in a first direction and a gate line extending in a second direction perpendicular to the first direction. And an intersecting data line and a pixel electrode. A thin film transistor (TFT) is formed in each pixel and is connected to the gate line, the data line, and the pixel electrode.

R, G, and B pixels, which are color filters, are formed on the second substrate 103 by a thin film process, and a common electrode facing the pixel electrode is formed. Therefore, the liquid crystal layer is arranged by voltages applied to the pixel electrode and the common electrode, thereby adjusting the transmittance of light provided from the backlight unit 130.

The gate driver 110 may be attached to one of the short sides of the first substrate 101, and the data driver 120 may have one long axis that is orthogonal to the gate driver 110. It is attached to the face. In this case, the gate driver 110 and the data driver 120 may be composed of a plurality of gate driver ICs integrated into one chip.

The backlight unit 130 may include a light source 170b for generating light, a light guide plate 150 for guiding the light incident from the light source 170b, and outputting the light in a specific direction, and the light source 170b and the light guide plate 150. It includes a storage container 160 for receiving.

The light source 170b may be configured of a plurality of light emitting diodes (LEDs) in the form of point light sources, and are disposed at one or both edges of the light guide plate 150 to generate light. The plurality of light emitting diodes (LEDs) are arranged to have a predetermined distance on the printed circuit board 170a disposed at the edge of the light guide plate 150.

The light source 170b and the printed circuit board 170a form a light source array 170.

The light source array 170 may be located at both edges of the light guide plate 150 and at one or more edges thereof.

The storage container 160 includes a bottom case 160b and a mold frame 160a.

The bottom case 160b includes a bottom surface and four sidewalls extending from the bottom surface. Four sidewalls of the bottom case 160b serve to guide the storage positions of the mold frame 160a and the light guide plate 150. In this case, the bottom case 160b and the mold frame 160a may be coupled to each other by hook fastening or the like.

The backlight unit 130 further includes a reflective plate 180 provided between the bottom surface of the bottom case 160b and the rear surface of the light guide plate 150. In addition, the backlight unit 130 further includes a plurality of optical sheets 140 disposed on the emission surface of the light guide plate 150.

The plurality of optical sheets 140 may improve the optical characteristics of the light emitted through the exit surface of the light guide plate 150 and may include a diffusion sheet, a prism sheet, and a protective sheet.

The light guide plate 150 should have high light refractive index and high light transmittance in order to minimize total reflection of light and absorption loss in the material. The light guide plate 150 has elasticity while having a specific hardness, and is easily bent when external force is applied. Once removed, material properties that are easily restored are required.

As the resin having all of these properties, a material of high transparency silicone or polyurethane series may be used. When not using a separate hardness supplement method, a polyurethane-based material that can sufficiently satisfy the required hardness by itself is used as the material of the light guide plate 150.

In this case, the light guide plate 150 is in a state in which no light scattering pattern is formed.

The reflective plate 180 is disposed to face the lower surface of the light guide plate 150 and is accommodated in the storage container 160. The reflective plate 180 reflects the light emitted to the lower portion of the light guide plate 150 among the light incident on the light guide plate 150. As such, the light reflected by the reflector 180 is reincident into the light guide plate 150.

The light guide plate 150 and the reflective plate 180 are attached to each other through an adhesive pattern (not shown). The adhesive pattern is applied to the upper surface of the reflective plate 180 in a predetermined pattern form and attached to the light guide plate 15. The adhesive pattern breaks the total reflection condition of the light guide plate 150 to emit light to the exit surface of the light guide plate 150.

The adhesive pattern positioned between the light guide plate 150 and the reflecting plate 180 is a light-transmitting polymer adhesive having a refractive index greater than or similar to that of the light guide plate 150, and removes the air layer between the two mediums. It destroys the total reflection condition that occurs when the light proceeds and serves to transmit the light to the reflecting plate 180.

Light transmitted through the reflective plate 180 is diffusely reflected to be emitted to the exit surface of the light guide plate 150.

FIG. 2 is a cross-sectional view taken along the line II ′ of FIG. 1.

As illustrated in FIGS. 1 and 2, an adhesive pattern 200 is formed between the light guide plate 150 and the reflecting plate 180. The adhesive pattern 200 is applied on the reflective plate 180 at various shapes and intervals and attached to the lower part of the light guide plate 150.

The adhesive pattern 200 serves to remove the air layer between the light guide plate 150 and the reflecting plate 180 and has a refractive index similar to or the same as that of the light guide plate 150. Therefore, total reflection does not occur at the portion where the adhesive pattern 200 is positioned, and light passing through the light guide plate 150 and the adhesive pattern 200 is transmitted to the reflecting plate 180 and is diffusely reflected from the reflecting plate 180. The light guide plate 150 is emitted to the upper surface.

For example, in the portion A where the adhesive pattern 200 is not formed, the light generated by the light source 170b is totally reflected and proceeds inside the light guide plate 150. The light generated from the light source 170b in the portion B on which the adhesive pattern 200 is formed passes through the light guide plate 150 and the adhesive pattern 200 and proceeds to the reflecting plate 180 and the reflecting plate 180. Diffuse reflection is emitted to the upper surface of the light guide plate 150.

This is a total reflection condition generated when the adhesive pattern 200 has a refractive index similar to or the same as that of the light guide plate 150 and removes an air layer between the light guide plate 150 and the reflecting plate 180 to advance light from a dense medium to a small medium. Because it destroys.

For this reason, the light provided to the light incident part of the light guide plate 150 passes through the reflective plate 180 through the adhesive pattern 200, is diffusely reflected on the reflective plate 180, and is emitted to the outside.

In this case, the adhesive pattern 200 is a light-transmissive polymer adhesive material that can transmit light, and is made of a material that removes the air layer between the two media of the light guide plate 150 and the reflective plate 180 such as an adhesive, an adhesive, and a photocuring agent. Can be.

The light transmissive polymer adhesive material includes cyanoacrylate, polyethylene terephthalate, polyacrylate, polyurethane, epoxy, silicone resin and photocurable resin. In addition, the light transmitting polymer adhesive material may include any one or more components of a thickener, a curing accelerator and a plasticizer.

The liquid crystal display according to the present invention, which attaches the light guide plate 150 and the reflective plate 180 by applying an adhesive pattern 200 on the reflective plate 180, uses a light guide plate 150 using an injection method, a printing method, and a laser. Compared to the existing liquid crystal display device having the light scattering pattern formed on the surface, it is easier to manufacture and the manufacturing cost can be reduced.

In addition, the liquid crystal display according to the present invention may increase light output efficiency due to diffuse reflection of the reflector 180 using the adhesive pattern 200 and minimize the loss of light generated from the light source 170b.

The shape and shape of the adhesive pattern 200 may be variously modified depending on conditions.

3 is a plan view illustrating a pressure-sensitive adhesive pattern applied on the reflector of FIG. 2 according to the first embodiment.

As illustrated in FIGS. 2 and 3, a plurality of adhesive patterns 200 spaced at regular intervals are coated on the reflecting plate 180. The plurality of adhesive patterns 200 have the same shape and the same spacing. As the adhesive pattern 200 is coated on the reflective plate 180, an air layer is removed at a portion where the adhesive pattern 200 is disposed between the light guide plate 150 positioned on the reflective plate 180 and the reflective plate 180. do.

The air layer is removed between the light guide plate 150 and the reflecting plate 180 at the portion where the adhesive pattern 200 is applied, so that the light generated from the light source (170b of FIG. 2) is applied to the light guide plate 150 and the adhesive pattern 200. Through the reflecting plate 180 is diffusely reflected.

When the adhesive pattern 200 is applied on the reflective plate 180 at the same shape and at the same interval, a luminance difference may occur at a portion away from the light incident portion of the light guide plate 150 and the light incident portion of the light guide plate 150. have.

Therefore, in order to minimize the luminance difference, as shown in FIG. 4, the adhesion pattern 300 applied on the reflecting plate 280 is moved away from the light incidence portion of the light guide plate 150 in FIG. 2. The interval can be adjusted differently. In other words, as the distance from the light incident portion of the light guide plate 150 increases, the distance between the adhesive patterns 300 applied on the reflective plate 280 may be densely adjusted.

When the light sources (170b of FIG. 2) are respectively provided at both side surfaces of the light guide plate 150, the light guide plate 150 is applied onto the reflective plate 280 toward the center of the light guide plate 150 at both light incident portions of the light guide plate 150. The space | interval of the adhesion pattern 300 becomes dense.

The adhesive pattern 300 may be applied on the reflective plate 280 in a circular shape as well as a circular shape. When the adhesive pattern 300 is in the form of a line, the distance between the lines may be densely adjusted as it moves away from the light incident part of the light guide plate 150.

The adhesive pattern 300 replaces the light scattering pattern formed on the light guide plate by using a printing method, a laser method, or the like, and may be set to correspond to a condition corresponding to the light scattering pattern formed on the existing light guide plate.

FIG. 5 is experimental data comparing luminance of a liquid crystal display including a pressure-sensitive adhesive pattern and a conventional liquid crystal display having a light scattering pattern formed on a light guide plate by using a printing and laser method.

As shown in FIG. 5, the experimental data is a graph showing the results of measuring luminance of four portions in the liquid crystal display according to the present invention and the conventional liquid crystal display.

Luminance (nit) measured in the liquid crystal display according to the present invention coated with a plurality of adhesive patterns on the reflecting plate is measured by the conventional liquid crystal display device in which a light scattering pattern is formed on the light guide plate using a laser and a printing method. nit).

Therefore, the liquid crystal display according to the present invention can realize the luminance in the conventional liquid crystal display device or higher by applying a plurality of adhesive patterns on the reflecting plate even without forming any light scattering pattern on the light guide plate.

As described above, the liquid crystal display device of the present invention does not form a light scattering pattern on the light guide plate, but applies a pressure-sensitive adhesive pattern on the reflecting plate to form a light scattering pattern on the light guide plate using a printing method or a laser method. Compared to the device, the manufacturing process is easier and mass production is possible.

In addition, the manufacturing cost can be reduced compared to a conventional liquid crystal display device in which a light scattering pattern is formed on a light guide plate using a printing method, a laser method, or the like.

In addition, in the liquid crystal display according to the present invention, the adhesive pattern removes the air layer between the light guide plate and the reflecting plate so that the light generated from the light source is transmitted through the light guide plate and the adhesive pattern to the reflecting plate to improve the diffuse reflection output efficiency of the reflecting plate. It is possible to minimize the loss of light generated in the.

Although the present invention has been described with reference to the embodiments illustrated 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.

100 liquid crystal display panel 101 first substrate
103: second substrate 110: gate driver
120: data driver 130: backlight unit
140: optical sheet 150: light guide plate
160: storage container 160a: mold frame
160b: bottom case 170: light source array
170a: printed circuit board 170b: light source
180, 280: Reflective plate 190: Top case
200, 300: Adhesive pattern

Claims (14)

A light source for generating light;
A light guide plate including a light incident part to which light generated from the light source is incident;
A reflection plate positioned under the light guide plate and reflecting light emitted from the light guide plate under the light incident to the light guide plate; And
And a plurality of adhesive patterns applied on the reflective plate at specific intervals to attach the light guide plate and the reflective plate.
The plurality of adhesive patterns is a backlight unit, characterized in that consisting of a light-transmitting polymer adhesive material having a refractive index similar to the light guide plate. The method according to claim 1,
The plurality of pressure-sensitive adhesive pattern is a backlight unit, characterized in that the shape and spacing is adjusted so as to have a tighter gap away from the light incident portion of the light guide plate. The method according to claim 1,
The plurality of adhesive patterns may remove the air layer between the light guide plate and the reflecting plate to destroy the total reflection conditions generated when the light generated from the light source proceeds from the dense medium to the medium. The method according to claim 1,
And the light provided to the light incident part of the light guide plate is diffusely reflected by the reflective plate through the light guide plate and the adhesive pattern at a portion where the adhesive pattern is formed. The method according to claim 1,
The adhesive pattern is a light-transmissive polymer adhesive material, the backlight unit, characterized in that composed of any one of an adhesive, an adhesive, and a photocuring agent. The method of claim 5,
The light transmissive polymer adhesive material includes a cyanoacrylate, polyethylene terephthalate, polyacrylate, polyurethane, epoxy, silicone resin, and photocurable resin. The method of claim 6,
The light transmitting polymer adhesive material comprises a component of any one or more of a thickener, a curing accelerator and a plasticizer. A liquid crystal display panel displaying an image;
A light source for irradiating light onto the liquid crystal display panel;
A light guide plate including a light incident part to which light generated from the light source is incident;
A reflection plate positioned under the light guide plate and reflecting light emitted from the light guide plate under the light incident to the light guide plate; And
And a plurality of adhesive patterns applied on the reflective plate at specific intervals to attach the light guide plate and the reflective plate.
And the plurality of adhesive patterns are made of a light transmitting polymer adhesive material having a refractive index similar to that of the light guide plate. The method of claim 8,
The plurality of adhesive patterns are characterized in that the shape and spacing of the plurality of adhesive patterns are adjusted to have a tighter gap as the distance from the light incident portion of the light guide plate. The method of claim 8,
The adhesive pattern removes the air layer between the light guide plate and the reflecting plate to destroy the total reflection conditions generated when the light generated from the light source proceeds from the dense medium to the medium. The method of claim 8,
And the light provided to the light incident part of the light guide plate is diffusely reflected through the light guide plate and the reflective pattern through the light guide plate and the adhesive pattern at a portion where the adhesive pattern is formed. The method of claim 8,
The adhesive pattern is a translucent polymer adhesive material, the liquid crystal display device, characterized in that composed of any one of an adhesive, an adhesive, and a photocuring agent. The method of claim 12,
The light transmissive polymer adhesive material may include cyanoacrylate, polyethylene terephthalate, polyacrylate, polyurethane, epoxy, silicone resin, and photocurable resin. The method of claim 13,
The light-transmitting polymer adhesive material comprises a component of any one or more of a thickener, a curing accelerator and a plasticizer.

Images