WO2014168387A1

WO2014168387A1 - Inverse prism-type optical element

Info

Publication number: WO2014168387A1
Application number: PCT/KR2014/002975
Authority: WO
Inventors: 고재호; 이정민; 이동철; 김영일; 민지홍
Original assignee: 주식회사 엘엠에스
Priority date: 2013-04-10
Filing date: 2014-04-07
Publication date: 2014-10-16
Also published as: KR20140122444A

Abstract

The present invention relates to an inverse prism-type optical element, and more specifically, to an inverse prism-type optical element having improved reliability and durability. The present invention comprises: a damage-preventing protective sheet comprising a non-smooth pattern having a random cross-sectional shape; and an inverse prism sheet comprising a plurality of prism patterns formed on top of the damage-preventing protective sheet and protruding in the direction of the damage-preventing protective sheet. The damage-preventing protective sheet eliminates damage due to contact between a light guide plate and the inverse prism sheet, thereby resolving the problems of scratching the light guide plate or damaging the peaks of the prism sheet of the optical element due to pressing during assembly or use.

Description

Inverse prism type optical element

The present invention relates to an inverted prism type optical element, and more particularly, to an inverted prism type optical element with improved reliability and durability.

In general, a liquid crystal display (LCD) requires a backlight unit that provides uniform light to the entire screen, unlike a conventional CRT.

1 is an exploded perspective view showing a conventional backlight unit, Figure 2 is a cross-sectional view showing a backlight unit provided with a conventional anti-prism sheet.

As shown in FIG. 1, a conventional backlight unit is disposed under a light source 1, a reflector 2 reflecting light emitted from the light source 1, and a light guide plate 3. It is composed of a reflective sheet (4) to increase the efficiency of use of light by reflecting again. Here, the reflecting plate 2 reflects the light emitted from the light source 1 toward the light guide plate 3, and is disposed on one side of the light guide plate 3.

In addition, a diffusion sheet 5 for uniformly diffusing light is disposed on the light guide plate 3 in the backlight unit, and prism sheets 6 and 7 for condensing scattered light on the diffusion sheet 5. Is placed. Here, each prism sheet 6, 7 has a prism pattern 8, 9 comprising a plurality of prisms projecting upwards.

The upper and lower prism sheets 6 and 7 are arranged so that the extending directions of the prism patterns 8 and 9 are perpendicular to each other to condense light.

However, the conventional backlight unit as described above requires two prism sheets 6 and 7 as shown in FIG. 1, which increases manufacturing costs and increases the number of processes and limits the thickness of the backlight unit. have.

On the other hand, in order to solve the above problems, as shown in Figure 2, the reverse prism sheet 10 has been recently developed.

The inverted prism sheet 10 is implemented in a form in which the prism pattern 12 protrudes downwardly, that is, in a direction toward the light guide plate 3.

In the reverse prism sheet 10, the light incident from the light guide plate 3 is totally reflected on the inner side of the prism 11 and is emitted upward. Accordingly, there is an advantage in terms of thickness and manufacturing cost than using two prism sheets.

However, the inverted prism sheet 10 as described above also has a problem. As the protruding prism pattern 12 faces the light guide plate 3, the inverted prism sheet 10 faces the light guide plate 3. The case where the apex contacts the light guide plate 3 occurs. As a result, scratches may occur on the light guide plate 3 or the vertices of the prism pattern 12 may be damaged. Due to such a problem, the optical properties of the entire device are changed, resulting in device defects, and as a result, the reliability and durability of the device are deteriorated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is to provide an inverted prism type optical device capable of improving reliability, durability, and optical defects.

Features of the reverse prism type optical element according to the present invention for solving the above problems, the damage prevention protective sheet and a damage prevention protective sheet formed on top of the damage prevention protective sheet including a non-flat pattern of a random cross-sectional shape It is composed of an inverted prism sheet including a plurality of prism patterns protruding in the sheet direction.

Preferably, the damage prevention protective sheet may include the non-flat pattern on at least one of the upper surface and the lower surface.

Preferably, the plurality of prism patterns provided in the inverse prism sheet may be formed in parallel with the vertices of the prism.

Preferably, the damage protection protective sheet may have a haze in the range of 1 to 35%.

Preferably, the non-flat pattern included in the damage prevention protective sheet may be formed as a surface having a plurality of fine protrusions.

Preferably, the height of the fine protrusions of the non-flat pattern may be 1 to 20㎛.

Preferably, the diameter of the fine protrusions of the non-flat pattern may be 1 to 40㎛.

Preferably, the non-flat pattern included in the damage prevention protective sheet may be formed as a surface having a plurality of fine grooves.

Preferably, the depth of the fine groove of the non-flat pattern may be 1 to 20㎛.

Preferably, the diameter of the fine groove of the non-flat pattern may be 1 to 40㎛.

Preferably, the non-flat pattern included in the damage prevention protective sheet may be formed as a surface having a plurality of convex partitions.

Preferably, the width of the divided area of the non-flat pattern may be 10 to 100㎛.

Preferably, the reverse prism sheet may be configured by being bonded by a protective sheet for preventing damage and an adhesive layer.

In the reverse prism type optical device according to the present invention, a damage preventing protective sheet is disposed between the light guide plate and the reverse prism sheet to remove damage caused by contact between the light guide plate and the reverse prism sheet.

By arranging the damage preventing protective sheet as in the present invention between the light guide plate and the reverse prism sheet, it is possible to solve the problem that scratches occur on the light guide plate of the optical element or the vertices of the reverse prism sheet are damaged due to the pressing during assembly or use. Therefore, the reliability and durability of the entire device can be improved.

1 is an exploded perspective view showing a conventional backlight unit;

2 is a cross-sectional view showing a backlight unit provided with a conventional anti-prism sheet;

3 is an exploded perspective view showing the configuration of a backlight unit including an inverted prism type optical device according to an embodiment of the present invention;

4 is a cross-sectional view showing the configuration of an inverted prism type optical device according to an embodiment of the present invention;

5 to 7 are plan views showing upper surface patterns of a damage preventing protective sheet disposed between the reverse prism sheet and the light guide plate in the reverse prism type optical element of the present invention;

8 to 9 are schematic diagrams showing convex partition patterns formed on the anti-prism type protective sheet;

10 is a cross-sectional view showing a configuration in which a separate adhesive layer is further included in an inverse prism type optical element; And

FIG. 11 is a cross-sectional view illustrating a configuration in which a separate adhesive layer is further included between the inverse prism type optical element and the light guide plate.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings. In the description of this embodiment, the same name and the same reference numerals are used for the same configuration and additional description thereof will be omitted.

In the following description, an inverted prism type optical device according to an embodiment of the present invention will be described with an example applied to a backlight unit of a liquid crystal display. However, the present invention is not necessarily limited thereto, and may be used as an optical element alone, or may be a backlight unit applied to other apparatuses other than the liquid crystal display device. Any device may be applicable.

3 is an exploded perspective view showing the configuration of a backlight unit according to an embodiment of the present invention, Figure 4 is a cross-sectional view showing the configuration of an inverted prism type optical device according to an embodiment of the present invention.

Referring to FIG. 3, the backlight unit includes a light source 1, a reflecting plate 2, a light guide plate 3, and an inverted prism type optical element, wherein the inverted prism type optical element is an inverted prism sheet 110 and a damage preventing device. A protective sheet 140 is included.

The light source 1 is a kind of lamp and generates light in response to the driving power source.

The light source 1 may be formed of, for example, a cold Cathode Fluorescent Lamp (CCFL) having an elongated cylindrical shape. In contrast, the light source 1 may be formed of an external electrode fluorescent lamp (EEFL) having electrodes formed on outer surfaces of both ends. In addition, the light source 1 may include a plurality of light emitting diodes (LEDs).

The reflecting plate 2 reflects the light generated by the light source 1 toward the light guide plate 3.

Light incident from the light source 1 toward the light guide plate 3 causes total reflection inside the light guide plate 3, and light incident on the surface of the light guide plate 3 at an angle of incidence smaller than the critical angle is transmitted without being totally reflected. . Light emitted to the upper side of the light guide plate 3 travels toward the reverse prism sheet 110.

The light guide plate 3 may be formed of, for example, polymethyl methacrylate (PMMA) or polycarbonate (PC) material.

The inverse prism sheet 110 includes a base film 130 and a prism pattern 120 formed of a transparent material such as polyester (PET), and the prism pattern 120 is formed on a lower surface of the base film 130. It may be formed using a UV curable resin or a heat curable resin. That is, the prism pattern 120 may be formed by applying a curable resin on the lower surface of the base film 130, pressing the stamp with a predetermined pattern, and curing the curable resin using UV or heat. .

The prism pattern 120 included in the anti-prism sheet 110 includes a plurality of prisms that protrude in the direction of the light guide plate 3.

The pitch of the prism pattern 120 included in the inverse prism sheet 110 may be 10 to 50 μm. The pitch of the prism panel 120 refers to the distance between the vertices of two adjacent prisms.

The prisms of the prism pattern 120 are configured to be parallel to the edge of the light guide plate 3 adjacent to the light source 1.

A plurality of prisms of the prism pattern 120 is preferably formed parallel to each other.

The damage prevention protective sheet 140 is disposed between the light guide plate 3 and the reverse prism sheet 110. That is, the damage prevention protective sheet 140 is disposed above the light guide plate 3 and disposed below the reverse prism sheet 110.

The damage prevention protective sheet 140 transmits the light emitted from the light guide plate 3 to the reverse prism sheet 110 while preventing the damage of the prism pattern 120.

The damage prevention protective sheet 140 may include a base film formed of a transparent material such as polyester (PET) and a non-flat pattern having a random cross-sectional shape formed on the surface of the base film. The non-flat pattern may be included in at least one of the upper and lower surfaces of the damage prevention protective sheet 140.

The non-flat pattern may be formed on the surface of the damage prevention protective sheet 140 by using a UV curable resin or a heat curable resin. That is, it may be formed in such a way that after applying the curable resin on the surface of the base film is pressed with a stamp having a predetermined pattern and curable the curable resin using UV or heat.

Damage prevention protective sheet 140 may have a haze in the range of 1 to 35%. Here, the turbidity is the degree of blur that appears when light passes through the sample, the sample in the present invention refers to the protective sheet 140 for preventing damage. Turbidity is expressed as the ratio of Diffuse Transmittance (DT) divided by Total Transmittance (TT) and calculated as follows.

Haze = (DT / TT) x 100 (unit,%)

Here, the diffuse transmitted light (DT) is the amount of light scattered in the light transmitted through the sample (lux) and the total transmitted light (DT) is the amount of all the light transmitted through the sample. On the other hand, parallel transmission light (Parallel Transmittance (PT)) is the amount of transmitted light without causing scattering in the transmitted light PT may be represented as TT-DT.

Damage prevention protective sheet 140 forms a non-flat pattern on the upper surface to reduce the contact area between the prism pattern 120 vertex included in the anti-prism sheet 110 and the damage prevention protective sheet 140, Wet Out Optical defects such as) can be reduced. Here, the wet out is a phenomenon that occurs when the change of the refractive index is removed when two sheet surfaces are in optical contact with each other and light is transferred from one sheet to the next sheet. It means a phenomenon that is recognized as an abnormal or defective part.

The non-flat pattern included in the damage prevention protective sheet 140 may be formed as a surface having a plurality of fine protrusions. The protrusion height of the fine protrusions is preferably 1 to 20 μm, and the diameter of the fine protrusions is preferably 1 to 40 μm.

As another example, the non-flat pattern included in the damage prevention protective sheet 140 may be formed as a surface having a plurality of fine grooves. The depth of the fine groove is preferably 1 to 20㎛, the diameter of the fine groove is preferably 1 to 40㎛.

The micro-projections and the micro-grooves generally have a circular shape in planar projection, but may have various shapes such as ellipses or polygons, and may have different shapes and sizes. The diameter when the planar projection shape of the fine projection and the microgroove is not a circle is defined as the maximum value of the distances between two points on the edge of the planar projection shape.

As another example, the non-flat pattern included in the damage prevention protective sheet 140 may be formed as a wave-shaped surface or a surface having a plurality of convex partitions. It is preferable that the width | variety of the said division area is 10-100 micrometers.

The width of the divided area is defined as the maximum value of the distances between two points on the edge of each divided area in planar projection.

5 to 7 are plan views showing shapes in which a non-flat pattern is formed on an upper surface of the damage preventing protective sheet 140 of the present invention.

FIG. 5 illustrates a non-flat pattern having a plurality of fine protrusions, wherein the protection sheet 140 for preventing damage has a turbidity of 7%, and FIG. 6 illustrates a non-flat pattern in which a plurality of fine grooves are formed to have a turbidity of 13%. will be. 7 is a non-flat pattern having a large number of divided regions, which has a turbidity of 7%. The divided regions may be formed in various shapes as shown in the schematic diagrams of FIGS. 8 and 9. Specifically, the shape of each partition may be circular or elliptical, and may have a shape such as a rhombus or a polygon. If the non-planar pattern is formed of such a divided region, the flat region is reduced than the fine protrusion of FIG. 5 and the fine groove of FIG. 6, thereby further reducing the contact area between the vertices of the prism pattern 120, thereby reducing the wet-out phenomenon. Can be further reduced.

Here, turbidity may vary according to surface roughness and surface waviness.

In addition, the damage protection protective sheet 140 may include a non-flat pattern on the upper surface and the lower surface of the damage prevention protective sheet 140. That is, the anti-corruption protection sheet 140 may include a non-flat pattern on both sides. By including a non-flat pattern on both sides of the damage prevention protective sheet 140 as described above, the diffusion function can be adjusted, the damage prevention protective sheet 140 and the anti-prism sheet 110 and the damage prevention protective sheet 140 and the light guide plate Optical defects can be reduced by reducing the contact area with (3).

The non-flat pattern formed on the upper and lower surfaces of the damage prevention protective sheet 140 may be different. That is, the non-flat patterns formed on the upper and lower surfaces may be independently selected from the above-described patterns.

Alternatively, the upper surface and the lower surface of the damage prevention protective sheet 140 may be formed in the same non-flat pattern. When formed with the same non-flat pattern, the size and position of the fine protrusions, the fine grooves and the convex partitions may be variously adjusted.

Next, a case where the reverse prism sheet 110 and the damage prevention protective sheet 140 are bonded to each other will be described.

10 is a cross-sectional view illustrating a configuration in which an additional adhesive layer 150 is further included in an inverted prism type optical device.

As shown, the reverse prism type optical element may include a reverse prism sheet 110, a damage preventing protective sheet 140, and an adhesive layer 150.

The adhesive layer 150 may be configured to be included between the reverse prism sheet 110 and the anti-damage protection sheet 140, the anti-prism sheet 110 by the adhesive layer 150 is a damage prevention protective sheet ( 140). In this case, when the non-flat pattern is formed only on the lower surface of the damage prevention protective sheet 140, the adhesive layer 150 may be formed on the upper surface of the damage prevention protective sheet 140.

However, when the anti-prism sheet 110 is bonded with the damage prevention protective sheet 140, the prism pattern 120 is formed by forming a prism pattern 120 with a material having an adhesive property without including an additional adhesive layer 150. The apex of the may be configured to be bonded to the upper surface of the protective sheet for preventing damage (140).

When the non-flat pattern is formed on the upper surface of the damage prevention protective sheet 140, the prism pattern 120 formed of an adhesive material may be bonded to the non-flat pattern.

When the non-flat pattern is formed on the upper surface of the protection sheet 140 for preventing damage, the non-flat pattern may be formed of an adhesive material instead of the prism pattern 120.

Next, a case where the damage prevention protective sheet 140 is bonded to the light guide plate 3 will be described.

FIG. 11 is a cross-sectional view illustrating a configuration in which a separate adhesive layer 160 is further included between the damage prevention protective sheet 140 and the light guide plate 3.

As shown, the adhesive layer 160 may be included between the lower portion of the protection sheet 140 for preventing damage of the reverse prism type optical element and the upper part of the light guide plate 3, and is reversed by the adhesive layer 160. The damage prevention protective sheet 140 of the prism type optical element may be bonded to the light guide plate 3.

The adhesive layer 160 may be formed on the upper surface of the light guide plate 3.

On the other hand, when the non-flat pattern is formed on the lower surface of the damage prevention protective sheet 140, it may be bonded by forming a non-flat pattern of the lower surface with a material having adhesiveness without using a separate adhesive layer 160. .

Although the reverse prism sheet 110 is formed by being bonded to the damage preventing protective sheet 140 or the damage preventing protective sheet 140 is formed by being bonded to the light guide plate 3, the reverse prism sheet 110 is described. ) And the damage prevention protective sheet 140 and the light guide plate 3 may be formed in one configuration by being bonded by the above-described adhesive method.

As described above, the preferred embodiments of the present invention have been described, and the fact that the present invention can be embodied in other specific forms in addition to the above-described embodiments without departing from the spirit or scope thereof has ordinary skill in the art. It is obvious to them. Therefore, the above-described embodiments are to be considered as illustrative and not restrictive, and thus, the invention is not limited to the above description, but may vary within the scope of the appended claims and their equivalents.

Claims

Damage prevention protective sheet including a non-flat pattern of a random cross-sectional shape; And

An inverted prism sheet formed on the damage preventing protective sheet and including a plurality of prism patterns protruding in the direction of the damage preventing protective sheet;

Inverted prism type optical element comprising a.
The method of claim 1,

The damage prevention protective sheet,

Inverse prism type optical element comprising the non-flat pattern on at least one of the upper surface and the lower surface.
The method of claim 1,

The plurality of prismatic patterns provided in the inverted prism sheet, wherein the vertices of the prism are formed in parallel with each other, the inverse prism type optical element.
The method of claim 1,

The damage preventing protective sheet has a haze in the range of 1 to 35%.
The method of claim 1,

The non-flat pattern included in the damage prevention protective sheet is formed of a surface having a plurality of fine protrusions, the inverse prism type optical element.
The method of claim 5,

The height of the fine projection of the non-flat pattern is inverse prism type optical element, characterized in that 1 to 20㎛.
The method of claim 5,

Inverse prism type optical element, characterized in that the diameter of the fine projection of the non-flat pattern is 1 to 40㎛.
The method of claim 1,

The non-flat pattern included in the damage prevention protective sheet is formed of a surface having a plurality of fine grooves inverse prism type optical element.
The method of claim 8,

Inverse prism type optical element, characterized in that the depth of the fine groove of the non-flat pattern is 1 to 20㎛.
The method of claim 5,

Inverse prism type optical element, characterized in that the diameter of the fine groove of the non-flat pattern is 1 to 40㎛.
The method of claim 1,

The non-flat pattern included in the damage preventing protective sheet is formed of a surface having a plurality of convex partitions, the inverse prism type optical element.
The method of claim 5,

Inverse prism type optical element, characterized in that the width of the divided region of the non-flat pattern is 10 to 100㎛.
The method of claim 1,

The reverse prism sheet is inverted prism type optical element, characterized in that the adhesive sheet by the damage prevention protective sheet and the adhesive layer.