KR100829693B1 - Reflection sheet, back light uint using thereof and liquid crystal display using thereof - Google Patents

Abstract

A reflection sheet, a backlight unit using the same, and an LCD using the same are provided to prevent a path of reflected light from being concentrated in a specific direction by diffusedly reflecting the light by using a reflection layer and metal particles included in the reflection layer, thereby preventing a bright line and accordingly improving image quality. A reflection sheet(115) comprises a base layer(200), and a reflection layer(210) disposed in front of the base layer. The reflection sheet desirably includes a light blocking layer(230). The reflection layer includes plural metal particles(220) where reflectivity of light of 550nm wavelength is more than 50%. At least one of the plural metal particles is a plate shape. At least one of the plural metal particles is a bead shape. The reflection layer further comprises an inorganic particle of a bead shape. The metal particle is at least one particle selected from a group comprising Cr, Ag, Au, Cu, Pd, Ir, Rh, Pt, Al, Ni, Ti, W, Be, Si or Fe.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflective sheet, a backlight unit using the same and a liquid crystal display using the same,

1 is a view for explaining a liquid crystal display device according to an embodiment of the present invention;

2 is a view for explaining the structure of the reflection sheet in more detail;

3A to 3C are diagrams for explaining the function of the reflective layer.

4 is a view for explaining another example of the reflection sheet;

5 is a view for explaining another example of the reflection sheet;

6 is a view for explaining another example of the reflection sheet;

Description of the Related Art

100: liquid crystal display panel 101: thin film transistor substrate

102: color filter substrate 110: backlight unit

111: optical sheet 111a: diffusion sheet

111b: prism sheet 111c: protective sheet

112: light source 113: light source housing

114: light guide plate 115: reflective sheet

The present invention relates to a reflective sheet, a backlight unit using the same, and a liquid crystal display using the same.

In general, a liquid crystal display (LCD) is a display device that displays a desired image by adjusting the light transmittance of a plurality of pixels arranged in a matrix in accordance with image information.

Since the liquid crystal display device displays an image by adjusting the amount of light coming from the outside, a separate light source for illuminating the liquid crystal display device, that is, a backlight unit is inevitably required.

In addition, the backlight unit includes a reflective sheet that reflects light emitted to the rear of the light guide plate.

The conventional reflective sheet has a problem of low reflection efficiency. As a result, the light efficiency of the conventional backlight unit is lowered and the efficiency of the conventional liquid crystal display device is lowered.

An object of the present invention is to provide a reflective sheet improved in reflection efficiency by including metal particles in a reflective layer included in a reflective sheet, a backlight unit using the reflective sheet, and a liquid crystal display using the same.

A reflective sheet according to an embodiment of the present invention includes a base layer and a reflective layer disposed on a front surface of the base layer and including a plurality of metal particles.

Further, at least one of the plurality of metal particles is in a plate form.

At least one of the plurality of metal particles is in the form of a bead.

Further, the reflective layer further includes inorganic particles in the form of beads.

The metal particles are at least one particle selected from the group consisting of Cr, Ag, Au, Cu, Pd, Ir, Rh, Pt, Al, Ni, Ti, W, Be, Si or Fe.

Further, the metal particles are metal particles having a reflectance of 50% or more of light having a wavelength of 550 nm.

Further, a shielding layer for shielding light emitted from the base layer from being emitted to the outside is further disposed on the back surface of the base layer.

Also, the backlight unit according to an embodiment of the present invention includes a light source and a reflective sheet for reflecting the light emitted from the light source, wherein the reflective sheet is disposed on the front surface of the base layer and the base layer, As shown in Fig.

Further, at least one of the plurality of metal particles is in a plate form.

At least one of the plurality of metal particles is in the form of a bead.

Further, the reflective layer further includes inorganic particles in the form of beads.

The metal particles are at least one particle selected from the group consisting of Cr, Ag, Au, Cu, Pd, Ir, Rh, Pt, Al, Ni, Ti, W, Be, Si or Fe.

Further, the metal particles are metal particles having a reflectance of 50% or more of light having a wavelength of 550 nm.

Further, a shielding layer for shielding light emitted from the base layer from being emitted to the outside is further disposed on the back surface of the base layer.

According to another aspect of the present invention, there is provided a liquid crystal display comprising a liquid crystal display panel, a light source disposed under the liquid crystal display panel, and a reflective sheet disposed under the light source, And a reflective layer disposed on the front surface and including a plurality of metal particles.

Further, at least one of the plurality of metal particles is in a plate form.

At least one of the plurality of metal particles is in the form of a bead.

Further, the reflective layer further includes inorganic particles in the form of beads.

The metal particles are at least one particle selected from the group consisting of Cr, Ag, Au, Cu, Pd, Ir, Rh, Pt, Al, Ni, Ti, W, Be, Si or Fe.

Further, the metal particles are metal particles having a reflectance of 50% or more of light having a wavelength of 550 nm.

Further, a shield layer is disposed on the back surface of the base layer to shield light emitted from the base layer from being emitted to the outside.

Hereinafter, a reflective sheet according to an embodiment of the present invention, a backlight unit using the reflective sheet, and a liquid crystal display using the same will be described in detail with reference to the accompanying drawings.

1 is a view for explaining a liquid crystal display according to an embodiment of the present invention. Here, FIG. 1 illustrates an edge type in which the light source 112 is disposed on the side of the light guide plate 114, and the position of the light source 112 is not limited to FIG.

Referring to FIG. 1, a liquid crystal display includes a liquid crystal display panel (Liquid Crystal Panel) 100 and a backlight unit (110).

The liquid crystal display panel 100 includes a thin film transistor substrate 101 and a color filter substrate 102 disposed against the thin film transistor substrate 101. The color filter substrate 102 and the thin film transistor substrate 101 (Not shown).

Here, the liquid crystal can be sealed after being injected between the thin film transistor substrate 101 and the color filter substrate 102.

The liquid crystal display panel 100 may further include a front polarizer (not shown) attached to the front surface of the color filter substrate 102 and may include a rear polarizer (not shown) attached to the rear surface of the thin film transistor substrate 101, As shown in FIG.

In this liquid crystal display panel 100, liquid crystal cells constituting pixel units are arranged in a matrix form, and the light transmittance of liquid crystal cells is adjusted according to a video signal supplied from a driving circuit (not shown) An image can be displayed by selectively transmitting light provided from the backlight unit 110 disposed on the back surface of the display panel 100. [

The backlight unit 110 preferably includes a light guide plate 114, a reflective sheet 115, a light source 112, a light source housing 113, and an optical sheet 111. In this backlight unit 110, the light guide plate 114 may be omitted depending on the position where the light source 112 is disposed. For example, the light guide plate 114 may be omitted in the case of the direct type in which light is directly emitted from the lower portion of the liquid crystal display panel 100 to the liquid crystal display panel 100.

The light source 112 is disposed below the liquid crystal display panel 100 and emits a predetermined light. The light source 112 may be a cold cathode fluorescent lamp (CCFL), an external electrode fluorescent lamp (EEFL), a light emitting diode (LED), or the like. In order to emit light, a plurality of light sources may be provided.

The light guide plate 114 is disposed in parallel with the liquid crystal display panel 100 on the back surface of the liquid crystal display panel 100 and converts the light emitted from the light source 112 into a surface light source. It is preferable that the thickness of the light guide plate 114 becomes gradually smaller toward the light-receiving portion than the light-incident portion where the light from the light source 112 is incident. It is also preferable that a prism-like pattern is formed on the back surface. The prism-shaped pattern functions to further enhance the brightness of light emitted from the light guide plate 114 to the liquid crystal display panel 100. [

Here, the light guide plate 114 shown in FIG. 1 is a kind of structure applied to a small-sized monitor such as a notebook computer, and the light guide plate 114 in the present invention is not limited to the structure shown in FIG.

The optical sheet 111 prevents the shape of the light source 112 from being displayed on the display surface of the liquid crystal display panel 100 and allows the light source 112 to operate as a light source having a uniform uniform brightness distribution. The optical sheet 111 may include a diffusion sheet 111a and a prism sheet 111b to improve the light scattering effect generated by the light source 112. [ In addition, a protective sheet 111c may be disposed on the front surface of the prism sheet 111b.

The reflective sheet 115 is disposed under the light source 112. For example, in the case of an edge type, the light guide plate 114 is disposed in parallel with the light guide plate 114 at the back surface thereof to reflect light emitted to the rear of the light guide plate 114. The structure of the reflective sheet 115 will be described in more detail with reference to FIG. 2 attached hereto.

2 is a view for explaining the structure of the reflection sheet in more detail.

2, the reflection sheet 115 includes a base layer 200 and a reflection layer 210 disposed on the entire surface of the base layer 200. Referring to FIG. In addition, the reflective sheet 115 may further include a shielding layer 230. A shielding layer 230 is disposed on the back surface of the base layer 200 and shields light emitted from the base layer 200 from being emitted to the outside.

The base layer 200 provides a space in which the reflective layer 210 is to be formed. The base layer 200 may be made of a material having optical transparency, for example, polyethylene terephthalate (PET).

The reflective layer 210 can reduce light loss by reflecting the light emitted from the light source 112 in the direction of the liquid crystal display panel 100 again. The reflective layer 210 includes a plurality of metal particles 220. Here, the metal particles 220 may be metal particles having a relatively high reflectance. Preferably, the metal particles 220 are at least one particle selected from the group consisting of Cr, Ag, Au, Cu, Pd, Ir, Rh, Pt, Al, Ni, Ti, W, have.

In order to sufficiently ensure the reflection efficiency of the reflection layer 210, it is more advantageous that the metal particles 220 included in the reflection layer 210 are particles of metal having a reflectance of 50% or more of light having a wavelength of 550 nm.

The reflective layer 210 may be formed by various methods such as a vacuum deposition method such as a sputtering method and an E-Beam method, a direct printing method, a screen printing method, a spray printing method, have. An example of a method for manufacturing the reflective layer 210 will be described below.

First, metal particles 220 are provided. For example, plate-shaped metal particles or bead-shaped metal particles are provided.

Then, the prepared metal particles 200 are mixed with a binder, a curing agent, a solvent or the like. Here, at least one of a thermosetting binder and a photocurable binder may be used as the binder. In addition, an anti-UV additive, an anti-scratch additive, etc. may be further mixed together with a binder, a curing agent, a solvent and the like. It is also possible that the resin material is further mixed.

Thereafter, the mixed material is applied to the entire surface of the base layer 200 by screen printing.

Thereafter, when the drying or baking process is performed, the solvent or the like is evaporated to form the reflective layer 210 including the metal particles 220.

At least one of the plurality of metal particles 220 included in the reflective layer 210 may be in the form of a plate. The function of the reflective layer 210 will be described in more detail with reference to FIGS. 3A to 3C.

3A to 3C are views for explaining the function of the reflective layer.

3A shows a case where the metal particles 220 are not included in the reflective layer 210. FIG.

3A, when light is incident on the reflective layer 210 from a light guide plate (not shown), incident light is reflected in a certain direction. As a result, the reflection efficiency of light incident in a specific direction can be lowered. Then, the light efficiency of the backlight unit is lowered, and the efficiency of the liquid crystal display device may be lowered.

Next, it is assumed that a plurality of light sources 112 are disposed on the back surface of the liquid crystal display panel 100, unlike the case of FIG. 1, as in the case of FIG. 3B. Here, in Fig. 3B, an example of the direct lower type will be described.

3A, if the metal particles 220 are not included in the reflective layer 210, the traveling direction of the light reflected by the reflective layer 210 is constant, and accordingly, The light from the light source 112 can be concentrated to a certain position on the liquid crystal display panel 100.

3B, the luminance of the image at the position 300 on the liquid crystal display panel 100 which does not correspond to the light source 112 is lower than the luminance of the liquid crystal display panel 100 corresponding to the light source 112. [ Is lower than the luminance of the image at the position on the image plane. Accordingly, a phenomenon in which a band (hereinafter referred to as a " bright line ") appears on the liquid crystal display panel 100 occurs. Then, the image quality of the image displayed on the liquid crystal display panel 100 deteriorates.

In contrast, when the reflective layer 210 includes a plurality of metal particles 220 as in the exemplary embodiment of the present invention, incident light may be incident on the reflective layer 210 and the reflective layer 210 And the reflection efficiency of the light incident in almost all directions is sufficiently ensured, whereby the reduction in the reflection efficiency can be prevented.

In addition, when the reflective layer 210 includes a plurality of metal particles 220, the incident light is irregularly reflected by the reflective layer 210 and the metal particles 220 included in the reflective layer 210 as in the case of FIG. 3C It is possible to prevent the traveling path of the reflected light from being concentrated in a specific direction. 3B, even when a plurality of light sources 112 are arranged on the rear surface of the liquid crystal display panel 100 as in the case of FIG. 3B, The image quality of the image displayed on the panel is prevented from deteriorating, thereby improving the image quality of the image.

Also, if the distribution of the metal particles 220 included in the reflection layer 210 is irregular, the reflection efficiency and the image quality of the image can be further improved.

As described above, the metal particles 220 included in the reflective layer 210 are formed of a metal material, preferably Cr, Ag, Au, Cu, Pd, Ir, Rh, Pt, , W, Be, Si, or Fe, reflection efficiency of light by the reflective layer 210 and the metal particles 220 can be further improved.

In addition, since the metal particles 220 included in the reflection layer 210 are particles of metal having a reflectance of 50% or more of light having a wavelength of 550 nm, the reflection efficiency of light by the reflection layer 210 and the metal particles 220 can be further improved have.

Next, Fig. 4 is a view for explaining another example of the reflection sheet. Here, in FIG. 4, the description of the contents described in detail above will be omitted.

Referring to FIG. 4, the shape of the metal particles 400 included in the reflection layer 210 may be a distorted plate shape. For example, in the manufacturing process of the reflective layer 210, the shape of the plate-shaped metal particles 400 may be uniformed by the pressure applied when the plate-shaped metal particles 400 are mixed with the binder or the like. Alternatively, when preparing plate-shaped metal particles, the shape of the metal particles may be uniform due to the applied pressure.

If the metal particles 400 included in the reflection layer 210 have a distorted shape, irregular reflection of the incident light can be further induced.

In addition, when the size of the metal particles 400 included in the reflective layer 210 is different from each other, irregular reflection of the incident light can be further induced.

5 is a view for explaining another example of the reflection sheet. Here, in FIG. 5, the description of the contents described in detail above will be omitted.

5, it is preferable that the reflective layer 210 further includes bead-shaped metal particles 500a and 500b in addition to plate-shaped metal particles 220a and 220b.

In addition, the reflective layer 210 may further include bead-shaped inorganic particles 510a, 510b, and 510c.

If the reflective layer 210 further includes bead-shaped metal particles 500a and 500b or bead-shaped inorganic particles 510a, 510b, and 510c in addition to plate-shaped metal particles 220a and 220b, The diffuse reflection of light can be further induced.

Next, Fig. 6 is a view for explaining another example of the reflection sheet. 6, the description of the contents described in detail above will be omitted.

6, the base layer 600 has a rugged front surface, and a reflective layer 610 may be disposed on the rugged front surface.

When the reflective layer 610 is disposed on the entire surface of the rugged base layer 600, irregular reflection of the incident light can be further induced.

As described above, it is to be understood that the technical structure of the present invention can be embodied in other specific forms without departing from the spirit and essential characteristics of the present invention.

It should be understood, therefore, that the embodiments described above are to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than the foregoing description, And all changes or modifications derived from equivalents thereof should be construed as being included within the scope of the present invention.

A reflective sheet according to an embodiment of the present invention, a backlight unit using the same, and a liquid crystal display using the reflective sheet according to an embodiment of the present invention include a reflective layer that includes a plurality of metal particles to increase reflection efficiency of the reflective sheet, The efficiency of the apparatus is increased.

In addition, since at least one of the plurality of metal particles is metal particles in a plate form, the reflection efficiency of the reflection sheet is improved, and the image quality of the image displayed on the liquid crystal display panel is improved.

Claims (21)

The base layer A reflective layer disposed on the front surface of the base layer, the reflective layer including a plurality of metal particles having a reflectance of 50% . The method according to claim 1, Wherein at least one of the plurality of metal particles is in the form of a plate. The method according to claim 1, Wherein at least one of the plurality of metal particles is in the form of a bead. The method according to claim 1, Wherein the reflective layer further comprises inorganic particles in the form of beads. The method according to claim 1, Wherein the metal particles are at least one particle selected from the group consisting of Cr, Ag, Au, Cu, Pd, Ir, Rh, Pt, Al, Ni, Ti, W, Be, Si or Fe. delete The method according to claim 1, And a shield layer for shielding light emitted from the base layer from being emitted to the outside is further disposed on a back surface of the base layer. A light source, And a reflective sheet for reflecting light emitted from the light source, The reflective sheet The base layer A reflective layer disposed on the front surface of the base layer, the reflective layer including a plurality of metal particles having a reflectance of 50% . 9. The method of claim 8, Wherein at least one of the plurality of metal particles is in the form of a plate. 9. The method of claim 8, Wherein at least one of the plurality of metal particles is in the form of a bead. 9. The method of claim 8, Wherein the reflective layer further comprises bead-shaped inorganic particles. 9. The method of claim 8, Wherein the metal particles are at least one particle selected from the group consisting of Cr, Ag, Au, Cu, Pd, Ir, Rh, Pt, Al, Ni, Ti, W, Be, Si or Fe. delete 9. The method of claim 8, And a shielding layer that shields light emitted from the base layer from being emitted to the outside is further disposed on a back surface of the base layer. A liquid crystal display panel; A light source disposed under the liquid crystal display panel; And And a reflective sheet for reflecting light emitted from the light source, Lt; / RTI > The reflective sheet The base layer A reflective layer disposed on the front surface of the base layer, the reflective layer including a plurality of metal particles having a reflectance of 50% And the liquid crystal display device. 16. The method of claim 15, Wherein at least one of the plurality of metal particles is in the form of a plate. 16. The method of claim 15, Wherein at least one of the plurality of metal particles is in the form of a bead. 16. The method of claim 15, Wherein the reflective layer further comprises bead-shaped inorganic particles. 16. The method of claim 15, Wherein the metal particles are at least one particle selected from the group consisting of Cr, Ag, Au, Cu, Pd, Ir, Rh, Pt, Al, Ni, Ti, W, Be, Si or Fe. delete 16. The method of claim 15, And a shielding layer that shields light emitted from the base layer from being emitted to the outside is further disposed on a back surface of the base layer.

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