KR101871550B1 - Optical sheet and liquid crystal display comprising the same - Google Patents

Abstract

And a prism portion including a base film and a plurality of prisms formed on a lower surface of the base film, wherein the prism portion is a light incidence surface, and the prism includes a first surface and a second surface formed adjacent to the first surface and wherein the second surface is the second surface including a curved surface, and wherein the prism is connected to, the apex of the prism T, the second R _n, T and R the trough of the surface _n in the cross section of the prism the one arbitrary point present between the T and R _n R _m, the normal to the lower surface of the base film to the normal to the lower surface of the base film through a T through the nd1, R _n ndn , the normal to the lower surface of the base film through the R _m ndm, angle θ the angle of the first surface and the normal nd1 forming the tangent and normal nd1 of the of the second surface θ _L1, T forming _R1 , the tangent and normal of _Rn in the second surface When it ndn this angle is θ _Rn, the second tangent and normal ndm the forming engraving inclination angle at the R _m of the plane θ _Rm forms, optical, including that of the optical sheet, and this satisfies the equation 1 and equation 2 A display device is provided.

Description

TECHNICAL FIELD [0001] The present invention relates to an optical sheet and a liquid crystal display including the optical sheet.

The present invention relates to an optical sheet and a liquid crystal display device including the same.

A liquid crystal display device is operated by emitting light from a backlight unit through a liquid crystal panel. BACKGROUND ART In recent years, an inverted prism sheet having a prism on a light incident surface has been used for a liquid crystal display device. The reverse prism sheet can increase the luminance by condensing light.

The viewer generally watches the screen of the liquid crystal display device from the front. However, the viewer can view the screen of the liquid crystal display device on the side. Therefore, the liquid crystal display device including the reverse prism sheet should have a wide viewing angle as well as a light condensing. However, there is a loss of luminance when the viewing angle is widened. In recent years, attempts have been made to change the prism shape of the reverse prism sheet in order to minimize the loss of luminance and widen the viewing angle.

The background art of the present invention is disclosed in Japanese Laid-Open Patent Application No. 2013-190779.

An object of the present invention is to provide an optical sheet in which a prism is formed on a light-entering surface and a viewing angle can be widened.

Another problem to be solved by the present invention is to provide an optical sheet in which a prism is formed on a light-entering surface, a viewing angle is widened, and a light-condensing efficiency is not reduced, thereby eliminating luminance loss.

Another problem to be solved by the present invention is to provide an optical sheet capable of widening a viewing angle and preventing condensation efficiency from being reduced, thereby reducing luminance loss, even if a prism is formed on a light incidence surface and a polarizing plate is laminated.

Another object of the present invention is to provide a liquid crystal display device including the optical sheet.

The optical sheet of the present invention includes a base film and a prism portion including a plurality of prisms formed on a lower surface of the base film, wherein the prism portion is a light incident surface, and the prism is adjacent to the first surface and the first surface Wherein the second surface comprises a curved surface and the prism has a vertex of T and a bottom point of R _n , T and R _n in the cross section of the prism, the normal line to the second arbitrary point present between the T and R _n of the second surface that connects to the lower surface of the base film through the R _m, T on the lower surface of the base film through the nd1, R _n to the on normal ndn, normal to the lower surface of the base film through the R _m ndm, the first surface and the normal nd1 is the angle is θ _L1, the second tangent and normal nd1 of the T of the face forming angle θ _R1, tangent at R _n of the second surface When each of the normal make up the ndn _Rn is θ, and the second tangent and normal to the forming engraving ndm inclination angle at the side of the R _m to said θ _Rm, can satisfy the following formula 1 and formula 2:

<Formula 1>

θ _R1 ≤ θ _L1 ≤ θ _Rn

(only, θ _R1 ≠ θ _L1 ≠ θ _Rn)

<Formula 2>

? _R1 <? _Rm <? _Rn

The liquid crystal display of the present invention may include the optical sheet.

The present invention provides an optical sheet in which a prism is formed on a light incidence surface and a viewing angle is widened.

The present invention provides an optical sheet in which a prism is formed on a light incidence surface, a viewing angle is widened, and a light collection efficiency is not reduced.

The present invention provides an optical sheet which has a prism formed on a light-entering surface, and a viewing angle is widened even if a polarizing plate is laminated, and the light-condensing efficiency is not reduced.

The present invention provides a liquid crystal display device including the optical sheet.

1 is a perspective view of an optical sheet according to an embodiment of the present invention.
Fig. 2 is a partial cross-sectional view of I-II in the optical sheet of Fig. 1;
3 is a schematic view of an optical path in a prism in an optical sheet according to an embodiment of the present invention.
4 is an enlarged cross-sectional view of a prism of an optical sheet according to another embodiment of the present invention.
5 is an enlarged cross-sectional view of a prism of an optical sheet according to another embodiment of the present invention.
6 is a schematic perspective view of a liquid crystal display device according to an embodiment of the present invention.
7 is a conceptual diagram of an angle of incidence of the light guide plate.
8 is a perspective view of a light guide plate according to an embodiment of the present invention.
9 shows the light profile according to the light exit angle from the light guide plate.
10 shows the relative luminance value (y axis) along the viewing angle (x axis) when the optical sheet according to Example 1 and Comparative Example 1 is applied.

The present invention is not limited to the above embodiments and various changes and modifications may be made by those skilled in the art without departing from the scope of the present invention. The present invention may be embodied in many different forms and is not limited to the embodiments described herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and the same or similar components are denoted by the same reference numerals throughout the specification.

The terms "upper" and "lower" are defined with reference to the drawings, Quot; or "on" may include not only superimposition but also interposition of another structure in the middle. On the other hand, what is referred to as "directly on" or "directly above"

As used herein, the term "aspect ratio" means a ratio (maximum height / maximum width) of a maximum height to a maximum width of an optical pattern (e.g., a prism, a lenticular lens pattern, or a micro lens pattern).

As used herein, the term "radius of curvature" means a radius of a virtual circle having the curved surface as a part in an optical pattern having a curved surface.

In the present specification, the term " peak " means the point at the lowermost portion of the prism when calculated from the base film, and "low point " means the point at which the first or second surface of the prism meets the base film.

As used herein, "(meth) acrylic" means acrylic and / or methacrylic.

In the present specification, the "plane retardation (Re)" is represented by the following formula A:

<Formula A>

Re = (nx - ny) xd

(In the above formula A, nx and ny are the refractive indexes in the slow axis direction and the fast axis direction of the optical element at a wavelength of 550 nm, respectively, and d is the thickness (unit: nm) of the optical element concerned.

In the present specification, "1/2 viewing angle" means the absolute value of the viewing angle in the left direction, which is 1/2 of the front luminance value, when the front surface of the liquid crystal display device is 0 °, the right direction is + And the sum of the absolute values of the viewing angles in the right direction FWHM (Full Width at Half Maximum).

In this specification, the inclination angles,? _R1 ,? _L1 ,? _Rn , and? _Ln are both defined as angles smaller than 90 degrees.

In the drawings of the present specification, the x-axis is the light exit direction from the light source, and the x-axis, the y-axis, and the z-axis are orthogonal to each other.

Hereinafter, an optical sheet according to an embodiment of the present invention will be described with reference to FIGS. 1 to 3. FIG. 1 is a perspective view of an optical sheet according to an embodiment of the present invention. Fig. 2 is a partial cross-sectional view of I-II in the optical sheet of Fig. 1; 3 is a schematic view of a light path in a prism in an optical sheet according to an embodiment of the present invention.

Referring to FIG. 1, the optical sheet 100 according to the present embodiment may include a base film 110 and a prism portion 120. The upper surface of the base film 100 is a light exit surface, and the prism portion 120 is a light incidence surface. The prism portion 120 includes a surface to which light from the light guide plate (not shown in Fig. 1) is incident. In the optical sheet 100, the prism portion 120 is formed on the light incident surface, so that the light condensing efficiency can be increased.

The base film 110 supports the optical sheet 100 and can emit light incident from the prism portion 120.

The base film 110 may have a retardation (Re) in the plane direction of 0 nm or more. In one embodiment, the base film may be an isotropic film having a retardation (Re) in the plane direction of 0 nm to 3 nm. In another embodiment, the base film may be a phase difference film having a retardation in the plane direction (Re) of 3,000 nm or more, specifically 5,000 nm or more, more specifically 10,100 nm to 15,000 nm. In the retardation range, the optical sheet can prevent rainbow stains from being visible.

The thickness of the base film 110 is not limited, but may be 30 탆 to 300 탆, specifically 50 탆 to 150 탆. In the above range, it can be used in a liquid crystal display device. The base film 110 may be formed of an optically transparent, optically transparent thermoplastic resin or a composition comprising it. Specifically, the thermoplastic resin is selected from the group consisting of a polyester resin including a polyethylene terephthalate (PET) resin and a polyethylene naphthalate resin, a cellulose resin including a triacetylcellulose (TAC) resin, a polyacetal resin, Non-cyclic polyolefin resins including carbonic acid resin, carbonate resin, styrene resin, vinyl resin, polyphenylene ether resin, polyethylene and polypropylene, cycloolefin (COP) resin, acrylonitrile-butadiene- A polyether sulfone resin, a polyphenylene sulfide resin, a fluorine resin, and a (meth) acrylic resin.

The prism portion 120 is formed on the lower surface of the base film 110, and allows light incident from the light guide plate or the like to be emitted to the base film 110. The upper surface of the prism portion 120 is a flat surface and is bonded to the lower surface of the base film 110. The prism portion 120 is formed integrally with the base film 110. In the present specification, the term "prism portion" means a plurality of prisms arranged in one direction. In this specification, "integrally formed" means that no adhesive layer or adhesive layer is interposed between the prism portion and the base film.

The prism portion 120 may include a plurality of prisms 121. The prism 121 is arranged in the same direction as the light exit direction (X-axis direction in Fig. 1) from the light source (not shown in Fig. 1).

The prism 121 may include a first surface and a second surface, and the prism may satisfy Equation 1 and Equation 2 below. Therefore, the optical sheet according to the present embodiment can widen the viewing angle without loss of brightness. Hereinafter, the prism according to the present embodiment will be described in more detail with reference to FIGS. 2 and 3. FIG.

Referring to FIG. 2, the prism 121 includes a first surface 121a and a second surface 121b.

The first surface 121a is formed adjacent to the second surface 121b.

When the optical sheet 100 is used in a liquid crystal display device including a one-side edge type light source, the first surface 121a may be an incoming surface, and the second surface 121b may be a reflecting surface . When the optical sheet 100 is used in a liquid crystal display device including a both-side edge type light source, the first surface 121a may be a light incidence surface and the reflection surface, and the second surface 121b may be a light incidence surface and a reflection surface . Hereinafter, it is assumed that the first surface 121a is a light incidence surface and the second surface 121b is a reflection surface. When a double-sided edge light source is used, the first and second surfaces may serve as an incidence surface and a reflection surface, including the curved surface described below.

The first surface 121a may be a single plane. However, since the first surface 121a has a plurality of planes in the form of a polygonal surface, light can be incident on the optical sheet at various angles. Therefore, the light collection efficiency can be further increased, and the viewing angle can be further widened.

The second surface 121b reflects light from the first surface 121a and reflects the light onto the base film 110, and the second surface 121b may include a curved surface. 2 shows a prism in which the second surface 121b is a curved surface. However, if the prism satisfies the following equations (1) and (2), the second surface 121b may include a shape in which two or more curved surfaces are connected, or a combination of curved surfaces and planes.

2, the prism 121 is in a cross section of the prism 121, the apex of the prism 121 is T, the low viscosity of the second face (121b) of the prism 121, R _n, T, and R _n a second surface (121b) of the passage the nd1, R _n the normal to the lower surface (110a) of the base film 110 to any point passing through the R _m, T present between the T and R _n for connecting the the bottom face normal to ndm, the first surface (121a) on the lower surface (110a) of the base film 110 to pass the normal line ndn, R _m for (110a) of the base film 110 and the normal line nd1 that forming angle θ _L1, the second face (121b) of each of the tangent and normal to each nd1 the forming of the T is the tangential and normal ndn in R _n of θ _R1, the second face (121b) forming the θ _Rn, the 2 (which may be referred to as a "tilt angle") side (121b) of the R _m and the normal to the tangent of each ndm the forms in the θ _Rm when called, it may satisfy the following formula 1 and formula 2:

<Formula 1>

θ _R1 ≤ θ _L1 ≤ θ _Rn

(only, θ _R1 ≠ θ _L1 ≠ θ _Rn)

<Formula 2>

? _R1 <? _Rm <? _Rn

This shows a case where the second surface 121b of the prism 121 forms a concave curved surface when viewed from the inside of the prism.

Therefore, the optical sheet 100 can have a half viewing angle of 30 ° or more, specifically 30 ° to 45 ° with respect to the light entering 50% or more of the light output angle of 50 ° to 85 ° out of the total light output angle . In the above range, the viewing angle improving effect can be seen.

Referring to Figure 3, from the first surface (121a) of the prism 121, a second surface (121b) of each of R _m, R _{m ',} R _{m "light} LR _m, LR _{m reach',} LR _m" may broaden the optical sheet has a viewing angle by the direction of light honeycombs according to R _m, R _{m ',} where the R _{m "of} each moving in different directions, a second surface (121b). in addition, by satisfying the above formula 2 R ' _m , R' _{m '} , and R' _{m "} in the reflective surface when the conventional second surface is flat (indicated by a dotted line) LR ' _m , LR' _{m '} , and LR' _{m "} are directed in the same direction, the condensing efficiency is increased, but the viewing angle becomes narrower than that of the prism of this embodiment.

The prism 121 satisfies the above-described formula (2), whereby the second surface 121b of the prism 121 may include a curved surface. The radius of curvature of the curved surface may be 200 占 퐉 or less, specifically 50 占 퐉 to 100 占 퐉. In the above range, there may be an effect of improving the viewing angle. However, depending on the manufacturing and / or processing conditions of the prism of the prism 121, the second surface may include a plane. For example, 95% or more and less than 100% of the second side is a curved surface, and more than 0% and 5% or less may be a flat surface.

In one embodiment, the second side of the prism may include an area that satisfies Equation 3: Thus, the prism may have a large effect of improving the viewing angle:

<Formula 3>

? _Rm1 <? _Rm2

(In the formula 3, θ _Rm1 is R _m1 tilt angle, θ _Rm2 the inclination angle at the R _m2, R _m1, R _m2 are arbitrary point, R _m1 that exists between T and R _n each T than R _m2 of the Lt; / RTI &gt;

The prism is a prism having at least 90%, particularly 95% to 100%, such as 90% to 98% of the total length of one end face of the second face, . Within this range, there may be a light diffusion effect.

In one embodiment, the second surface of the prism satisfies Equation 3-1, and the inclination angle increases from T to R _n , which may result in a greater effect of improving the viewing angle:

<Formula 3-1>

? _R ? ₁ <? _Rm1 <? _Rm2 <? _Rm3 <? _Rn

(In the above formula 3-1, θ is the inclination angle of from _Rm1 R _m1, θ is the inclination angle of the _Rm2 from R _m2, θ _Rm3 are the same as defined in the inclination angle at the R _m3, θ _R1, θ _Rn is the equation 1, respectively, T is T as a low viscosity, the order of R _m1, R _m2, R _m3 is T and R _n any point existing between, R _m1, R _m2, R _m3 each in the surface apex, R _n is the second prism Lt; / RTI &gt;

The prism 121 may have a? _Rn -? _R1 of 1 ° to 20 °, specifically 3 ° to 15 °, more specifically 5 ° to 10 °. In the above range, the viewing angle may be improved without lowering the light collection efficiency.

The prism 121 may have theta _L1 of 25 DEG to 40 DEG, specifically, 31 DEG to 37 DEG. The prism 121 may have an angle &amp;thetas; _R1 of 15 DEG to 35 DEG, specifically, 23 DEG to 33 DEG. The prism 121 may have an angle θ _Rn of 25 ° to 45 °, specifically, 33 ° to 42 °. In the above range, the light converging efficiency is not lowered, and the viewing angle can be improved.

The aspect ratio of the prism 121 may be 0.6 or more, specifically 0.7 to 0.8. In the above range, the viewing angle may be improved without lowering the light collection efficiency.

The height H1 of the prism 121 may be 3 占 퐉 to 25 占 퐉, specifically, 7 占 퐉 to 14 占 퐉. The prism 121 may have a width P1 of 5 占 퐉 to 30 占 퐉, specifically, 5 占 퐉 to 18 占 퐉. In the above range, the viewing angle may be improved without lowering the light collection efficiency.

Prism may be a width of 40% to 60% (P1) of 121, a minimum distance between the prism (121) between the low R _n of normal nd1 and the prism 121 of the base film 110, which passes through the vertex T of. In this range, the optical loss can be minimized.

The prism 121 may be formed of the same or a different kind of material for the base film 110, or may be formed of a composition including an ultraviolet curable unsaturated compound, an initiator, and the like. As an example, the ultraviolet curable unsaturated compound may be at least one selected from the group consisting of epoxy (meth) acrylate, urethane (meth) acrylate, phenylphenol ethoxylated (meth) acrylate, trimethylolpropane ethoxylated (Meth) acrylate, phenoxybenzyl (meth) acrylate, phenylphenoxyethyl (meth) acrylate, ethoxylated thiodiphenyl di But are not necessarily limited thereto. The initiator may be a photopolymerization initiator, such as a ketone-based, phosphine oxide-based, or the like, but is not limited thereto.

Although not shown in FIG. 1, the prism 121 may include a light diffusing agent. Accordingly, the prism 121 can enhance the effect of improving the viewing angle by increasing the light diffusion effect. Although not shown in FIG. 1, a planar portion may be formed between the prism 121 and the adjacent prism 121. 1, the prism 121 and the neighboring prism 121 have the same height and width, but may be different from each other.

The optical sheet according to an embodiment of the present invention can be manufactured by a conventional method. For example, in an optical sheet according to an embodiment of the present invention, a resin for forming a prism is coated on a pulling roll having an engraved pattern of the same type as that of the prism according to an embodiment of the present invention, .

Hereinafter, an optical sheet according to another embodiment of the present invention will be described with reference to FIG. 4 is an enlarged cross-sectional view of a prism of an optical sheet according to another embodiment of the present invention.

An optical sheet according to another embodiment of the present invention includes a base film and a prism portion, and the prism portion may include a plurality of prisms of FIG. Is substantially the same as the optical sheet according to an embodiment of the present invention except that it includes the prism of Fig. 4 instead of the prism of Fig. Hereinafter, only the prism of FIG. 4 will be described.

Referring to FIG. 4, the prism 122 includes a first surface 122a and a second surface 121b, and the second surface 121b may satisfy Equation 1 and Equation 2 above. The first surface 122a may be a light incidence surface, and the second surface 121b may be a reflection surface.

Referring to FIG. 4, the prism 122 includes a first surface 122a and a second surface 121b, and the second surface 121b may satisfy Equation 1 and Equation 2 above. Then, the first surface (122a) is that the low viscosity of the apex of the prism 122 is T, the first surface (122a) of the prism (122) connected to L _n, T and L _n in the cross section of the prism 122 Let L _{m be} an arbitrary point existing between T and L _n of the first surface 122 a of the prism and let nd 1 and L _n be a normal to the lower surface 110 a of the base film 110 passing through T of at L ₁ base film ndn the normal to the lower surface (110a) of 110, ndm the normal to the lower surface (110a) of the base film 110 through the L _m, the first surface (122a) The angle formed by the tangent line and the normal line nd1 is θ _L1 , the angle formed by the tangent line at L _n in the first surface 122a and the normal line ndn is θ _Ln , the tangent at L _m in the first surface 122a is the normal line ndm (Hereinafter may be referred to as "inclination angle") is? _Lm , the following expression 4 can be satisfied:

<Formula 4>

? _L1 <? _Lm <? _Ln

By satisfying the expression (4), the optical sheet may have an effect of improving the viewing angle. This shows the case where the first surface of the prism is a concave surface when viewed from the inside of the prism. At this time, the first surface may have the same or different radius of curvature as the second surface.

In one embodiment, the first side of the prism may include a region that satisfies Equation 5 below: As a result, the effect of improving the viewing angle may be large.

&Lt; EMI ID =

? _Lm1 <? _Lm2

(In the formula 5, θ _Lm1 is the inclination angle of the L _m1, θ _Lm2 is the inclination angle of the L _m2, L _m1, L _m2 is an arbitrary point, L _m1 existing between L ₁ and L _n each is more L _m2 T).

In the prism, the area of the first surface that satisfies the above-mentioned formula 5 is 90% or more, specifically 95% to 100%, for example, 90% to 95% of the total length of one end face of the first surface, . Within this range, there may be a light diffusion effect.

In one embodiment, the first surface of the prism satisfies Equation 5-1, and the inclination angle increases from T to L _n , which may result in a greater effect of improving the viewing angle:

<Formula 5-1>

? _L ? 1 <? _Lm1 <? _Lm2 <? _Lm3 <? _Ln

(In the above formula 5-1, θ is the inclination angle of the L _{m1 Lm1, Lm2} is the inclination angle θ of the L _{m2, Lm3} θ is the inclination angle of the L _{m3, L1} θ, θ _Ln are as defined in formula 4, respectively, T is a T to a low point, the order of L _m1, L _m2, L _m3 is an arbitrary point present between the T and L _n, respectively, L _m1, L _m2, L _m3 at the surface apex, L _n is the first of the prism Lt; / RTI &gt;

At this time,? _L1 may be 15 ° to 37 °, specifically 23 ° to 37 °. At this time,? _Ln may be 25 ° to 45 °, specifically 33 ° to 42 °. In the above range, the light converging efficiency may not be lowered and the viewing angle may be improved.

Hereinafter, an optical sheet according to another embodiment of the present invention will be described with reference to FIG. 5 is an enlarged cross-sectional view of a prism in an optical sheet according to another embodiment of the present invention.

An optical sheet according to another embodiment of the present invention includes a base film and a prism portion, and the prism portion may include a plurality of prisms of FIG. Is substantially the same as the optical sheet according to an embodiment of the present invention except that it includes the prism of Fig. 5 instead of the prism of Fig. Hereinafter, only the prism of FIG. 5 will be described.

5, in the prism 123, the first surface 123a of the prism 123 may satisfy the following equation 6:

&Lt; EMI ID =

θ _L1 > θ _Lm > θ _Ln

(In the above Equation 6,? _L1 ,? _Lm ,? _Ln are as defined in Equation (4) above).

This shows a case where the first surface 123a of the prism is a convex surface when viewed from inside the prism. At this time, the first surface may have the same or different radius of curvature as the second surface.

In one embodiment, the first side of the prism may include an area that satisfies Equation (7): As a result, the effect of improving the viewing angle may be large.

Equation (7)

? _Lm1 >? _Lm2

(In the above equation 7 _{,? Lm1} and? _Lm2 are as defined in the above-mentioned 5).

In the prism, the area of the first surface that satisfies the above expression 7 is 90% or more, specifically 95% to 100%, for example, 90% to 95% of the total length of one end face of the first surface, . Within this range, there may be a light diffusion effect.

In one embodiment, the first surface of the prism satisfies Equation 7-1, and the inclination angle decreases from T to L _n , which may result in a viewing angle improving effect:

<Formula 7-1>

? _L1 >? _Lm1 >? _Lm2 >? _Lm3 >? _Ln

(In Formula 7-1 _{,? L1 ,? Lm1 ,? Lm2 ,? Lm3,? Ln} are as defined in 5-1).

At this time,? _L1 may be 25 ° to 45 °, specifically 33 ° to 42 °. At this time,? _Ln may be 15 ° to 37 °, specifically 23 ° to 37 °.

Hereinafter, a liquid crystal display according to an embodiment of the present invention will be described with reference to FIG. 6 is a schematic perspective view of a liquid crystal display device according to an embodiment of the present invention.

6, a liquid crystal display 1000 according to the present embodiment includes a light source 1010, a light guide plate 1020, an optical sheet 1030, and a reflective sheet 1040, And may include an optical sheet according to embodiments of the present invention. Therefore, in the liquid crystal display device according to the present embodiment, a half viewing angle is 30 degrees or more, for example, 30 degrees to 45 degrees, for light entering the light outgoing angle of 50 to 85 degrees and 50 percent or more of the total light outgoing angles . Within this range, the luminance reduction can be minimized.

Hereinafter, the light source 1010 and the reflective sheet 1040 will be described.

The light source 1010 generates light and may be disposed on the side of the light guide plate 1020, that is, opposite to the light incident surface of the light guide plate 1020. As the light source 1010, various light sources such as a linear light source lamp, a surface light source lamp, a CCFL, or an LED may be used. A light source cover is further formed outside the light source 1010 to protect the light source. 6 illustrates a case where the light source 1010 is disposed on only one side of the light guide plate 1020. However, the light source may be disposed on the other side of the light guide plate 1020 (the side opposite to the side face).

The reflective sheet 1040 is formed on the lower surface of the light guide plate 1020 and can reflect the light emitted from the light source 1010 and reflect it to the light guide plate 1020 to increase the light efficiency.

Hereinafter, the light guide plate 1020 will be described.

6, the light guide plate 1020 is disposed on a side surface of the light source 1010 and internally reflects light incident from the light source 1010 to be emitted to the optical sheet 1030.

The light guide plate 1020 allows light emitted from the light guide plate 1020 to be scattered and light of 50% or more emitted at a light output angle of 50 to 85 degrees, specifically 60 to 80 degrees, . Referring to FIG. 7, the above-mentioned "light outgoing angle" is defined as a direction perpendicular to the light exit surface of the light guide plate 1020 (L2 in FIG. 7) (front surface of the liquid crystal display device) The angle? Referring to FIG. 9, it can be confirmed that at least 50% of the total light outgoing angles among the light emitted from the light guide plate 1020 are emitted at a light outgoing angle of 50 ° to 85 °, specifically 60 ° to 80 °.

The light guide plate 1020 has a light incident surface facing the light source 1010, a light exit surface orthogonal to the light incident surface and facing the prism of the optical sheet 1030.

Hereinafter, the light guide plate according to the present embodiment will be described in detail with reference to FIG.

8, the light guide plate 1020 according to the present embodiment may include a base layer 1021, a lenticular lens pattern 1022, and a micro lens pattern 1023. [

The base layer 1021 can be formed between the lenticular lens pattern 1022 and the microlens pattern 1023 to support the lenticular lens pattern 1022 and the microlens pattern 1023. [ The upper surface of the base layer 1021 may be a light exit surface, the side surface of the base layer 1021 may be a light incidence surface, and the lower surface of the base layer 1021 may be a surface from which light enters from the micro lens pattern.

The base layer 1021 may have a thickness of 200 탆 to 1000 탆, specifically 300 탆 to 600 탆. And can be used in an optical display device in the above range.

The base layer 1021 may comprise a film formed of an optically transparent resin. Specifically, the resin may include at least one of polycarbonate, polymethyl (meth) acrylate (PMMA), polystyrene, a copolymer resin of methyl methacrylate and styrene (MS resin).

The lenticular lens pattern 1022 is formed on the upper surface of the base layer so as to emit light incident from the base layer and prevent the light from scattering, thereby increasing the brightness. 8 shows a light guide plate in which a lenticular lens pattern is formed by a first optical pattern, but the first optical pattern may include an optical pattern in which a curved surface is formed at the top. For example, the first optical pattern may include an optical pattern whose cross-section is a prism pattern and whose top is curved.

The lenticular lens pattern 1022 may have an aspect ratio of 0.10 to 0.50 and a radius of curvature of 5 占 퐉 to 200 占 퐉, specifically 10 占 퐉 to 150 占 퐉. In the above range, light can be diffused and diffused with respect to the incident light, and the viewing angle in the vertical direction can be narrowed, so that the visual feeling and the brightness can be increased.

The lenticular lens pattern 1022 may have a maximum width P2 of 5 占 퐉 to 100 占 퐉 and a maximum height H2 of 1 占 퐉 to 50 占 퐉. In the above range, the light efficiency can be enhanced, and light can be also diffused and diffused to the incident light.

The lenticular lens pattern 1022 may be formed of the same or different optical transparent resin as the base layer.

The microlens pattern 1023 is formed on the lower surface of the substrate layer, and can collect light emitted from the side surface of the light guide plate and emit light. 8 shows a light guide plate in which a microlens pattern is formed as a second optical pattern, but the second optical pattern may include a prism pattern having a cross section of n (n is an integer of 3 to 10) prisms, a lenticular lens pattern, and the like .

The microlens pattern 1023 may have an aspect ratio of 0.01 to 0.20, specifically 0.01 to 0.10. In this range, it is possible to increase the light collection efficiency of the outgoing light from the light guide plate.

The microlens pattern 1023 may have a width P3 of 10 mu m to 100 mu m and a height of 1 mu m to 10 mu m. In the above range, a condensing effect may be obtained when the prism sheet is used.

The microlens pattern 1023 may be formed of the same or different optical transparent resin as the base layer 1021. [

The base layer 1021, the lenticular lens pattern 1022, and the microlens pattern 1023 may be integrally formed. Means that the adhesive layer is not interposed between the substrate layer, the lenticular lens pattern, and the microlens pattern and is not independently separated. To this end, the light guide plate may be manufactured by forming a microlens pattern on the other surface of the base layer on which a lenticular lens pattern is extruded on one side by laser machining or the like. Extrusion and laser processing may be performed by conventional methods known to those skilled in the art.

Although not shown in FIG. 6, the liquid crystal display device may further include a polarizing plate, a liquid crystal panel, a window sheet, and the like.

Hereinafter, the configuration and operation of the present invention will be described in more detail with reference to preferred embodiments of the present invention. However, the following examples are provided to aid understanding of the present invention, and the scope of the present invention is not limited to the following examples.

Examples 1 to 3: Preparation of optical sheet

An ultraviolet ray curable resin was coated on a pull roll formed with a prismatic pattern having an intricate shape having the specifications shown in Table 1 below. One side of a polyethylene terephthalate (PET) film (thickness: 125 탆) was brought into contact with the obtained coating, and a light quantity of 200 mJ was irradiated at UV wavelength to prepare a prism sheet having a prism on one side of the PET film.

Comparative Example 1 to Comparative Example 2: Production of optical sheet

An ultraviolet ray curable resin was coated on a pull roll formed with a prismatic pattern having an intricate shape having the specifications shown in Table 1 below. One side of a polyethylene terephthalate (PET) film (thickness: 125 탆) was brought into contact with the obtained coating, and a light quantity of 200 mJ was irradiated at UV wavelength to prepare a prism sheet having a prism on one side of the PET film.

The following properties of the liquid crystal display devices prepared in Examples and Comparative Examples were evaluated, and the results are shown in Table 1 and FIG.

1. Fabrication of Light Guide Plate: A lenticular lens pattern (width: 21 mu m, height: 5.5 mu m, aspect ratio: 0.26, radius of curvature: 12 mu m) was formed on the top surface of a polycarbonate (PC) plate A micro-lens pattern (width: 30 탆, height: 2 탆, aspect ratio: 0.067) manufactured by a punching method was formed to manufacture a light guide plate.

2. Liquid crystal display assembly: A light guide plate and an optical sheet were stacked so that the lenticular lens pattern of the light guide plate and the prism of the embodiment and the comparative example were opposed to each other. A liquid crystal display device including a one-sided edge type LED light source was manufactured using an LED light source. The light emitted from the light guide plate showed an optical profile according to Fig. The viewing angle was measured using EZCONTRAST X88RC (EZXL-176R-F422A4, ELDIM). A full width at half maximum (FWHM) of 1/2 of the front luminance value was obtained based on the front face.

Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Prism width
(탆) 13 13 13 13 13 Height of prism (탆) 10 10 10 10 10 Incidence plane plane Concave surface Convex surface plane plane Reflective surface Concave surface Concave surface Concave surface plane Convex surface Curvature radius of reflecting surface
(탆) 100 100 100 - 100 θ _L1 (°) 33.0 29.6 36.4  33.0  33.0 θ _Ln (°) 33.0 36.4 29.6  33.0  33.0 θ _R1 (°) 29.6 29.6 29.6  33.0  36.4 θ _Rn (°) 36.4 36.4 36.4  33.0  29.6 the relationship of? _L1 ,? _R1 , and? _Rn ? _R1 <? _L1 <? _Rn ? _R1 =? _L1 <? _Rn ? _{R1 <} ? _L1
=? _Rn ? _R1 =? _L1 =? _Rn θ _R1 > θ _L1 > θ _Rn The relationship of? _R1 ,? _Rm ,? _Rn ? _R1 <? _Rm <? _Rn ? _R1 <? _Rm <? _Rn ? _R1 <? _Rm <? _{Rn R1} = θ _m θ = θR _Rn θ _R1 > θ _Rm > θ _Rn the relationship of? _L1 ,? _Lm ,? _Ln ? _L1 =? _Lm =? _Ln ? _L1 <? _Lm <? _Ln θ _L1 > θ _Lm > θ _Ln ? _L1 =? _Lm =? _Ln ? _L1 =? _Lm =? _Ln 1/2 Viewing Angle
(°)  40.4 44.2 39.1 27.3 18.6

As shown in Table 1 and FIG. 10, the optical sheet according to the present example did not decrease the light condensing efficiency, and the optical efficiency was high, and the viewing angle was increased by 1/2.

On the other hand, as shown in Table 1 and FIG. 10, the viewing angle of Comparative Example 1 including a prism whose plane of incidence and reflection surfaces were triangular in cross section was narrower than that of the present invention. In Comparative Example 2 in which the reflective surface did not satisfy Formula 2 of the present invention as a convex surface, the viewing angle was narrower than that of the present invention.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (18)

A base film and a plurality of prisms formed on a lower surface of the base film, wherein the prism portion is a light incident surface,
Wherein the prism includes a first surface and a second surface formed adjacent to the first surface,
Wherein the second surface comprises a curved surface,
The prism may be any point that in a cross section of the prism, is present between the apex of the prism T, the low viscosity of the second side R _n, T, and R _n and the second T, and R _n of the plane connecting the the R _m, the lower portion of the base film to the normal to the lower surface of the base film through the nd1, R _n the normal to the lower surface of the base film through a T through the ndn, R _m ndm the normal to the surface, the first surface and the normal nd1 is the angle is θ _L1, the second tangent of the angle in the θ _R1, R _n of the second face is tangential and normal nd1 of the T forms one plane and with the optical sheet to the normal line of ndn each meet the θ _Rn, and the second when the tangential and normal ndm the forming engraving inclination angle at the R _m of the surface to that θ _Rm, formula 1 and formula 2 forms,
<Formula 1>
θ _R1 ≤ θ _L1 ≤ θ _Rn
(only, θ _R1 ≠ θ _L1 ≠ θ _Rn)
<Formula 2>
? _R1 <? _Rm <? _Rn ,
Wherein the prism has an aspect ratio of 0.6 to 0.8,
And the second surface has a radius of curvature of 200 mu m or less. The optical sheet as claimed in claim 1, wherein the optical sheet has a half viewing angle of 30 degrees or more with respect to light that is 50% or more of the light output angle of 50 to 85 degrees out of the total light output angle. delete 2. The optical sheet according to claim 1, wherein the second surface is a curved surface, and the curved surface satisfies the above-mentioned formula (1) and formula (2). The optical sheet as claimed in claim 1, wherein the second surface comprises a region satisfying the following formula (3):
<Formula 3>
? _Rm1 <? _Rm2
(In the formula 3, θ _Rm1 is R _m1 tilt angle, θ _Rm2 the inclination angle at the R _m2, R _m1, R _m2 are arbitrary point, R _m1 that exists between T and R _n each T than R _m2 of the Lt; / RTI &gt; The optical sheet as claimed in claim 5, wherein the second surface has a larger inclination angle from T to R _n . The optical sheet according to claim 1, wherein the prism has an angle? _Rn -? _R1 of 1 to 20 degrees. The optical sheet according to claim 1, wherein the angle θ _L1 is 25 ° to 40 °, the angle θ _R1 is 15 ° to 35 °, and the angle θ _Rn is 25 ° to 45 °. delete The optical sheet of claim 1, wherein the first surface is planar. The optical sheet according to claim 10, wherein the first surface comprises a plurality of planes in the form of a polygonal surface. The optical sheet according to claim 1, wherein the first surface is a curved surface. The method of claim 12, wherein the first to L _n that the trough of the surface, gradually increasing the inclination angle from T to L _n,
The tilt angle is ndm the normal to the lower surface of the base film through the arbitrary point L _m, L _m existing in the claim between 1 if T and L _n for connecting the T and L _n, said first Is defined by an angle formed by a tangent at L _m and a normal ndm in the plane. 13. The method of claim 12, when the low viscosity of the first side to be called L _n, the smaller the inclination angle toward the L _n in T,
The tilt angle is ndm the normal to the lower surface of the base film through the arbitrary point L _m, L _m existing in the claim between 1 if T and L _n for connecting the T and L _n, said first Is defined by an angle formed by a tangent at L _m and a normal ndm in the plane. The optical sheet according to claim 1, wherein the first surface is a light incidence surface and the second surface is a reflective surface. A light source, a light guide plate formed adjacent to the light source, and an optical sheet according to any one of claims 1, 2, 4, 8, 10 to 15 formed on the upper surface of the light guide plate and,
Wherein the light guide plate and the prism of the optical sheet are opposed to each other. The liquid crystal display device according to claim 16, wherein the light guide plate emits light of 50% or more at a light output angle of 50 to 85 degrees. The liquid crystal display device according to claim 17, wherein the liquid crystal display device has a half viewing angle of 30 to 45 degrees.

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