KR20070099086A - Reflective polarizer film and display apparatus having the same - Google Patents

Abstract

A reflective polarizing film and a display device having the same are provided to increase luminance and luminance uniformity of a display screen by comprising a first reinforcing layer on a reflective polarizing layer and optical lenses on the surface of the first reinforcing layer. A reflective polarizing film(430) comprises the followings: a reflective polarizing layer(432) for transmitting the light vibrating in a first direction and reflecting the light vibrating in a second direction vertical to the first direction; a first reinforcing layer(434) formed on the upper side of the reflective polarizing layer and provided with convex optical lenses having a diameter of 30~60mum and the height occupying 30~50% of the diameter; and a second reinforcing layer(436) formed under the reflective polarizing layer to prevent the reflective polarizing layer from being wrinkled.

Description

Reflective polarizing film and a display device having the same {REFLECTIVE POLARIZER FILM AND DISPLAY APPARATUS HAVING THE SAME}

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

FIG. 2 is a cross-sectional view illustrating a combined cross section of the backlight assembly illustrated in FIG. 1.

FIG. 3 is an enlarged view enlarging an area A shown in FIG. 2.

4 is an enlarged view illustrating an enlarged area B of FIG. 3.

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

100: backlight assembly 200: storage container

300 lamp 410 diffuser plate

420: Diffusion sheet 430: Reflective polarizing film

500: mold frame 800: display unit

900: top chassis 1000: display device

The present invention relates to a reflective polarizing film and a display device having the same, and more particularly, to a reflective polarizing film for improving luminance characteristics and a display device having the same.

In general, the liquid crystal display (Liquid Crystal Display) is a flat panel display device that displays an image using a liquid crystal (Liquid Crystal), is thinner and lighter than other flat panel display devices, and has a low driving voltage and low power consumption It has advantages and is used extensively throughout the industry.

The liquid crystal display device includes a liquid crystal panel including a thin film transistor (TFT) substrate, a color filter substrate facing the TFT substrate, and a liquid crystal layer interposed between the two substrates to change light transmittance. do. In addition, since the liquid crystal display device is a non-light emitting device that does not emit light by the liquid crystal panel for displaying an image, it requires a backlight assembly for supplying light to the liquid crystal panel.

In general, the backlight assembly is classified into an edge type and a direct type. The edge type is a method in which a lamp is positioned on the side of the transparent light guide plate and the light is multiplexed by using one side of the light guide plate to emit light to the liquid crystal display panel. In the direct type, lamps are positioned directly under the liquid crystal display panel, and diffuser plates are disposed on the lamps to diffuse light generated from the lamps.

Meanwhile, the backlight assembly further includes optical sheets such as a diffusion sheet, two prism sheets, and a reflective polarizing film on an emission surface of the light guide plate or the diffusion plate in order to secure the advantages of improving the brightness of the output light and the viewing angle of the output light. do. Looking at the functions of each of the optical sheets, the diffusion sheet diffuses light to make the luminance of the display screen uniform. The prism sheet focuses light in the front direction to increase the brightness. Reflective polarizing film is recycled by passing P wave and reflecting S wave through polarization separation function. Accordingly, the brightness of the display screen is increased.

On the other hand, since the optical sheets account for a large portion of the manufacturing cost of the display device, recently, optical members are being developed that can reduce the number of sheets used by integrating the functions of different optical sheets.

Accordingly, the technical problem of the present invention is focused on such a conventional point, the object of the present invention is to provide a reflective polarizing film for improving the brightness characteristics of the display screen.

Another object of the present invention is to provide a display device having the above-mentioned reflective polarizing film.

In order to realize the above object of the present invention, the reflective polarizing film according to the embodiment includes a reflective polarizing layer and a first reinforcing layer. The reflective polarizing layer transmits light oscillating in a first direction and reflects light oscillating in a second direction perpendicular to the first direction. The first reinforcement layer is formed on the reflective polarization layer, and convex optical lenses are formed.

In accordance with another aspect of the present invention, a display device includes a display panel for displaying an image, a lamp unit for providing light to the display panel, and a reflective polarizing film disposed on the lamp unit. And a storage container accommodating the display panel, the lamp unit, and the reflective polarizing film. In this case, the reflective polarizing film includes a reflective polarizing layer for selectively reflecting and transmitting the light, and a reinforcing layer formed on the reflective polarizing layer and having convex optical lenses.

According to the reflective polarizing film and the display device having the same, the luminance and the luminance uniformity of the display screen can be improved by forming optical lenses for diffusing and condensing light in the reinforcing layer formed on the reflective polarizing layer.

Hereinafter, with reference to the accompanying drawings, it will be described in detail the present invention.

1 is an exploded perspective view illustrating a display device according to an exemplary embodiment of the present invention, and FIG. 2 is a cross-sectional view illustrating a combined cross section of the backlight assembly illustrated in FIG. 1.

1 and 2, a liquid crystal display device 1000 according to an exemplary embodiment of the present invention may include a backlight assembly 100 for supplying light, a display unit 800 for displaying an image using the light, and a display unit. A top chassis 900 for fixing 800.

The backlight assembly 100 includes a storage container 200, a lamp 300, an optical member 400, and a mold frame 500.

The storage container 200 is formed of a bottom portion 210 and four side portions 220 extending vertically from the bottom portion 210, whereby a storage space is formed to accommodate the lamp 300. The side portion 220 of the storage container 200 is bent while having a predetermined area thereon to support the optical member 400 disposed thereon. The storage container 200 is made of, for example, a metal material having low deformation and excellent strength.

A plurality of lamps 300 are arranged to be parallel to each other on the same plane. The lamps 300 generate light in response to driving power applied from the outside. For example, the lamps 300 may be formed of a cold cathode fluorescent lamp 300 (CFL) having an elongated cylindrical shape. The lamps 300 are preferably arranged at equal intervals for uniformity of brightness of the backlight assembly 100, and the number of lamps 300 may vary depending on the required brightness characteristics. In addition, the electrode 300 may be formed of an external electrode fluorescent lamp (EEEL) having external electrodes formed at both ends of the lamps 300.

The optical member 400 is disposed above the lamps 300 so as to improve brightness characteristics of light generated from the lamps 300 and is supported by the side portion 220 of the storage container 200. The optical member 400 includes a diffusion plate 410 disposed on the lamps 300, a diffusion sheet 420 and a reflective polarizing film 430 disposed on the diffusion plate 410.

The diffusion plate 410 first diffuses the light generated from the lamps 300 to improve luminance uniformity of the light. The diffusion plate 410 has a plate shape having a predetermined thickness to prevent bending in the downward direction in which the lamps 300 are formed. The diffusion plate 410 is made of a transparent material for transmitting light, and includes a diffusion agent for diffusing light. The diffusion plate 410 is made of, for example, a poly methyl methacrylate (PMMA) material.

The diffusion sheet 420 diffuses light provided from the diffusion plate 410 to make the luminance of the display screen more uniform. Meanwhile, an optical sheet having various functions may be further added to the upper and lower portions of the diffusion sheet 420 according to the luminance characteristics required for the backlight assembly 100. In addition, the diffusion sheet 420 may be omitted.

The reflective polarizing film 430 is an optical member that improves light efficiency by selectively transmitting and reflecting light passing through the diffusion sheet 420. However, in the reflective polarizing film 430 according to the present invention, since convex optical lenses 435 are formed on a surface of the reflective polarizing film 430 facing the liquid crystal display panel 810, light that is selectively transmitted is collected in the direction of the liquid crystal display panel 810. And spreading function. The reflective polarizing film 430 will be described later in detail with reference to FIGS. 3 to 4.

The mold frame 500 is coupled to the storage container 200 to surround the side portion 220 of the storage container 200. In addition, the mold frame 500 fixes the edge of the optical member 400 supported by the storage container 200. The mold frame 500 is made of, for example, a polymer material that is easy to manufacture using a mold.

Meanwhile, the backlight assembly 100 further includes a reflective sheet 600 disposed under the lamps 300. The reflective sheet 600 reflects the light provided in the downward direction from the lamps 300 in the upward direction. To this end, the reflective sheet 600 is made of a material having a high light reflectance. For example, the reflective sheet 600 is made of polyethylene terephthalate (PET) material or polycarbonate (PC) material.

The display unit 800 includes a liquid crystal display panel 810 for displaying an image and a driving circuit unit 820 for driving the liquid crystal display panel 810.

The liquid crystal display panel 810 is injected between the array substrate 812 for displaying pixels, the color filter substrate 814 facing the array substrate 812, and the array substrate 812 and the color filter substrate 814. The liquid crystal layer 816 is included.

The array substrate 812 is a TFT substrate in which thin film transistors (hereinafter referred to as TFTs) as switching elements are formed in a matrix form. A data line and a gate line are respectively connected to the source terminal and the gate terminal of the TFTs, and a pixel electrode made of a transparent conductive material is connected to the drain terminal.

In the color filter substrate 814, RGB pixels for realizing color are formed in a thin film form. The common electrode made of a transparent conductive material is formed on the color filter substrate 814.

In the liquid crystal display panel 810 having such a configuration, when power is applied to the gate terminal of the TFT and the TFT is turned on, an electric field is formed between the pixel electrode and the common electrode. The electric field changes the arrangement of the liquid crystal molecules of the liquid crystal layer 816 interposed between the array substrate 812 and the color filter substrate 814, and the light supplied from the backlight assembly 100 according to the arrangement change of the liquid crystal molecules. The transmittance is changed to display an image of a desired gray scale.

The driving circuit unit 820 may include a data printed circuit board 822 for supplying a data driving signal to the liquid crystal display panel 810, a gate printed circuit board 824 for supplying a gate driving signal to the liquid crystal display panel 810, and data. A data driving circuit film 826 connecting the printed circuit board 822 to the liquid crystal display panel 810 and a gate driving circuit film 828 connecting the gate printed circuit board 824 to the liquid crystal display panel 810. do.

The data driving circuit film 826 and the gate driving circuit film 828 are formed of, for example, a tape carrier package (TCP) or a chip on film (COF). Meanwhile, the gate printed circuit board 824 may be removed by forming separate signal wires on the liquid crystal display panel 810 and the gate driving circuit film 828.

The top chassis 900 is coupled to the storage container 200 to fix the edge of the liquid crystal display panel 810. In this case, the data printed circuit board 822 is bent by the data driving circuit film 826 and fixed to the bottom portion 210 or the side portion 220 of the storage container 200. The top chassis 900 is made of, for example, a metal having little deformation and excellent strength.

FIG. 3 is an enlarged view enlarging an area A shown in FIG. 2.

Referring to FIG. 3, the reflective polarizing film 430 includes a reflective polarizing layer 432, a first reinforcing layer 434, and a second reinforcing layer 436. The reflective polarization layer 432 selectively reflects and transmits light through a polarization separation function. As an example, the reflective polarizing layer 432 is a structure in which a plurality of films are alternately stacked with the same refractive index on the X-axis and different on the Y-axis. Reflect light on the axis. For example, the reflective polarization layer 61 transmits P waves among the components of light and continuously reflects S waves.

For example, the reflective polarization layer 432 may be formed of 3M Dual Brightness Enhancement Film (DBEF). Since the reflective polarization layer 432 is formed to have a thickness of approximately 130 μm, a support part for preventing the reflection of the reflective polarization layer 432 is required. Accordingly, the first reinforcement layer 434 and the first reinforcement layer 434 which can prevent the reflection of the reflective polarizing film 430 by increasing the overall thickness of the reflective polarizing film 430 on the upper and lower portions of the reflective polarizing layer 432. 2 reinforcement layer 436 is formed. The first reinforcement layer and the second reinforcement layer 434 and 436 may be formed of, for example, a transparent polycarbonate material.

Each of the first reinforcement layer 434 and the second reinforcement layer 436 may be formed to have a thickness of 50% to 150% of the thickness of the reflective polarization layer 432.

 In addition, the first reinforcement layer 434 and the second reinforcement layer 436 may be adhered to the reflective polarization layer 432 using a thermosetting resin or a UV curable resin having a refractive index of 1.4 to 1.6.

The first reinforcement layer 434 includes a first surface adhered to an upper surface of the reflective polarization layer 432 and a second surface opposite to the first surface. Convex optical lenses 435 are formed on the second surface. The optical lenses 435 may be formed simultaneously with the first reinforcing layer 436 by extruding the second surface of the first reinforcing layer 436 when the first reinforcing layer 436 is formed. In addition, the optical lenses 435 may be formed by coating an acrylic resin on the first reinforcing layer 434 having a flat surface and then extruding the acrylic resin.

The optical lens 435 is formed to have a diameter of 30 to 60㎛. More preferably, the optical lens 435 is formed to have a diameter of 50㎛. In addition, the optical lens 435 is formed to have a height corresponding to 30 to 50% of the diameter.

On the other hand, when the optical lens 435 is formed of a polycarbonate material, the optical lens 435 has a refractive index of approximately 1.57. When the optical lens 434 is formed of an acrylic resin, the optical lens 434 has a refractive index of approximately 1.49. The first reinforcement layer 434 is formed to have a haze value of 60% or more by the plurality of optical lenses 435.

The second reinforcement layer 436 includes a third surface adhered to the lower surface of the reflective polarization layer 432 and a fourth surface opposite to the third surface.

The fourth surface may be formed flat, or a concave-convex pattern 437 having a diameter of 10 to 30 μm may be formed. When the concave-convex pattern 437 is formed on the fourth surface, close contact with the diffusion sheet 420 may be prevented and scratches due to the collision with the diffusion sheet 420 may be reduced. The uneven pattern 437 may be formed to have a haze value of light passing through the second reinforcement layer 436 at least 10%.

More specifically, the haze value of the reflective polarizing film 430 including the first reinforcing layer 434 and the second reinforcing layer 436 is preferably 60% to 90%. More preferably, the reflective polarizing film 430 has a haze value of 80% to 90%.

When the uneven pattern 437 is formed on the fourth surface, the light provided from the diffusion sheet 420 is thirdly diffused by the uneven pattern 437. Subsequently, the light transmitted through the second reinforcing layer 436 is transmitted by the reflective polarization layer 432, and the P wave of the light component is transmitted and the S wave is reflected. The reflected S wave is re-reflected at the fourth surface and separated into P wave and S wave again. The P wave thus formed passes through the reflective polarization layer 432, and the S wave is reflected. Since this process is repeated continuously, it is possible to reduce the light loss.

Light passing through the reflective polarization layer 432 and reaching the first reinforcement layer 434 is diffused and collected by the optical lens 435. The first reinforcement layer 434 includes convex optical lenses 435 formed at a uniform density. Each optical lens 435 is easy to scatter light because its surface is curved. As a result, the light is effectively diffused, so that the luminance of the light emitted on the display screen can be made more uniform.

In addition, the optical lens 435 protruding toward the liquid crystal display panel condenses the light provided from the reflective polarization layer 432 toward the liquid crystal display panel.

4 is an enlarged view illustrating an enlarged area B of FIG. 3.

Referring to FIG. 4, light incident on the first reinforcement layer 434 is refracted at the surface of the optical lens 435 to be focused in a vertical direction toward the liquid crystal display panel. In this way, by applying the reflective polarizing film 430 having the diffusion and condensing functions, the luminance and the uniformity of the display screen can be improved. Accordingly, the use of various optical sheets, which have been conventionally used for the light condensing and diffusing functions, can be reduced, thereby reducing the manufacturing cost of the liquid crystal display device.

According to such a reflective polarizing film and a display device having the same, a first reinforcing layer for supporting the reflective polarizing layer is formed on the reflective polarizing layer for selectively transmitting and reflecting light, and the light is diffused on the surface of the first reinforcing layer. And by forming optical lenses for condensing, it is possible to improve the brightness and the uniformity of brightness of the display screen. As a result, the number of sheets of optical sheets used for condensing or diffusing light in a conventional display device can be reduced, thereby reducing manufacturing costs.

Although described above with reference to the embodiments, those skilled in the art can be variously modified and changed within the scope of the invention without departing from the spirit and scope of the invention described in the claims below. I can understand.

Claims (8)

A reflective polarizing layer for transmitting the light oscillating in the first direction and reflecting the light oscillating in the second direction perpendicular to the first direction; And And a first reinforcing layer formed on the reflective polarizing layer and having convex optical lenses formed thereon. The reflective polarizing film of claim 1, wherein the optical lens has a diameter of 30 to 60 μm. The reflective polarizing film of claim 2, wherein the height of the optical lens is 30 to 50% of a diameter. The reflective polarizing film of claim 3, further comprising a second reinforcing layer formed under the reflective polarizing layer and preventing the reflection of the reflective polarizing layer. The reflective polarizing film of claim 4, wherein each of the first and second reinforcing layers has a thickness of 50 to 150% of the thickness of the reflective polarizing layer. The reflective polarizing film of claim 4, wherein a plurality of uneven patterns are formed on a lower surface of the second reinforcement layer. The reflective polarizing film of claim 1, wherein the reflective polarizing layer is DBEF (DUAL BRIGHTNESS ENHANCEMENT FILM). A display panel displaying an image; A lamp unit providing light to the display panel; A reflective polarizing film disposed on the lamp unit and including a reflective polarizing layer selectively reflecting and transmitting the light and a reinforcing layer formed on the reflective polarizing layer and having convex optical lenses; And And a storage container accommodating the display panel, the lamp unit, and the reflective polarizing film.

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