KR20160147135A - Optical sheet and liquid crystal display comprising the same - Google Patents

Abstract

The present invention relates to an optical sheet and a liquid crystal display device including the same. The optical sheet comprises a base film and a plurality of prisms which are formed on a bottom surface of the base film. Each of the prisms includes a first surface and a second surface which is adjacent to the first surface. The second surface includes planar and curved surfaces. The prism satisfies formula 1: _R1 <= _L1 <= _Rn, wherein _R1 _L1 _Rn, and formula 2: _R1 < _Rm < _Rn, when in a cross section of the prism, an apex of the prism is T, a bottom point of the second surface is R_n, an arbitrary point of the curved surface of the second surface connecting the apex T and the bottom point R_n is R_m, a slope angle at the apex T of the first surface is _L1, a slope angle at the apex T of the second surface is _R1, a slope angle at the point R_m is _Rm, and a slope angle at the bottom point R_n is _Rn.

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 plane and a curved surface, wherein the prism has a vertex of T at a cross section of the prism, a bottom point of the second surface is R _n , T and R _n 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 to any point existing in the surface of the second surface through the R _m, T connect the ndn, the normal to the lower surface of the base film through the R _m ndm, the angle of the first surface and the normal nd1 forming θ _L1, wherein the angle forming the tangent and normal nd1 in of the second side T θ _R1, in R _n of the second surface This angle is the tangent and normal ndn forming θ _Rn, 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 an enlarged sectional view of a prism in an optical sheet according to another embodiment of the present invention.
7 is an enlarged cross-sectional view of a prism in an optical sheet according to another embodiment of the present invention.
8 is a schematic perspective view of a liquid crystal display device according to an embodiment of the present invention.
9 is a conceptual diagram of the light exit angle of the light guide plate.
10 is a perspective view of a light guide plate according to an embodiment of the present invention.
Fig. 11 shows the optical profile (x axis: light emission angle, y axis) according to the light exit angle from the light guide plate.

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" in this specification are defined with reference to the drawings, wherein "upper" may be changed to "lower", "lower" What is referred to as "on" may include not only superposition, but also intervening other structures 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" bottom point " means the point at which the first or second surface of the prism meets or closest to 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, the X axis is a light exit direction from a light source, and the X axis, Y axis, and 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 this range, the optical sheet can prevent rainbow stains from being visible.

Though the thickness of the base film 110 is not limited, it 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. However, a primer layer may be formed on the lower surface of the base film to improve the formation of the prism portion on the base film.

The prism portion 120 may include a plurality of prisms 121. The prisms 121 are arranged in the same direction as the light exit direction 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.

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

The second surface 121b may reflect light from the first surface 121a and reflect it to the base film 110. [ The second surface 121b may be in the form of one or more planes and one or more curved surfaces connected to each other.

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 said R _m any point existing in the second surface (121b) of the curved surface (121b ") of the prism to connect and, nd1 the normal to the lower surface (110a) of the base film 110 through the T, The normal to the lower surface 110a of the base film 110 passing through R _n is ndn and the normal to the lower surface 110a of the base film 110 passing through R _m is ndm, angle with the normal line nd1 the forming these angles are each tangent and normal nd1 of from T θ _L1, the second face (121b) forming the tangent and normal ndn in R _n of θ _R1, the second face (121b) forming θ (which may be referred to as a "tilt angle") _Rn, the second face (121b) of the R _m tangent and normal to each ndm the forming at a time to as θ _Rm, it can satisfy the following formula 1 and formula 2 (where, R _m and R _n is T and the different A):

<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 has a concave shape when viewed from the inside of the prism. θ _R1 ≠ θ _L1 ≠ θ _Rn means that θ _R1, θ _L1 , θ _Rn are excluded.

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.

2, the second surface 121b of the prism 121 includes a plane 121b 'and a curved surface 121b' ', which are connected to each other. Therefore, the optical sheet has a large effect of improving the viewing angle FIG. 2 shows the second surface in which one plane and one curved surface are connected. However, if the first surface and the second surface satisfy Formula 1 and Formula 2, the second surface or two or more planes, A second side to which more than one curved surface is connected may also be included in the scope of the present invention.

The plane 121b 'is formed closer to the apex T of the prism than the curved surface 121b ", and the second surface 121b can satisfy the following equation 3 in its cross-section:

<Formula 3>

? _{Rm1b '&} lt _{;? Rm1b} ?

(In the formula 3, θ _{Rm1b 'is} R _m1b' inclination angle at, θ _{Rm1b "is} R _m1b" inclination angle at, R _{m1b 'is} an arbitrary point of the second side plane, R _{m1b "is} the second R _{m1b '} and R _{m1b "} are different from each other. This shows a case where the second surface 121b has a concave shape when viewed from the inside of the prism. Therefore, the optical sheet may have a large effect of improving the viewing angle.

The curved surface 121b "may be 50% or more but less than 100%, specifically 70% to 95% of the total area of the second surface 121b. 'May be more than 0% but not more than 50%, specifically 5% to 30% of the total area of the second surface 121b. In the above range, the workability is easy and the light diffusion control effect can be obtained. Preferably, the area ratio of the second surface 121b to the curved surface 121b &quot; relative to the plane 121b 'may be greater than 1, for example between 2 and 30, for example between 2 and 20.

The curved surface 121b "in its cross-section can satisfy Equation 4 below:

<Formula 4>

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

(In the formula 4, θ _Rm1 is the inclination angle of the R _m1, θ _Rm2 the inclination angle at the R _m2, θ _Rm3 the inclination angle at the R _m3, θ _R1, θ _Rn are as defined in the formula (1), respectively, T is apex of the prism, _n R is low in the second plane, R _m1, R _{m2, m3} is R being located adjacent T in any order of the point, R _m1, R _{m2, m3} R of each of the curved surface). In this case, the curved surface 121b "increases in inclination angle from the point on the curved surface 121b" closest to T to the point on curved surface 121b " And the curved surface 121b "is a concave curved surface when viewed. The curved surface 121b "may have a radius of curvature of 200 占 퐉 or less, specifically 50 占 퐉 to 100 占 퐉. In this range, a viewing angle improving effect may be obtained.

2, the plane 121b 'is shown as one plane, but the plane 121b' may be a polygonal plane having a plurality of planes.

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 further 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.

1 also shows the case where the first surface 121a and the second surface 121b have different shapes and the first surface 121a has the same shape as the second surface 121b. .

Further, although not shown in FIG. 1, a polarizer may be further laminated on the upper surface of the base film 110. An adhesive layer, an adhesive layer, and a barrier layer having adhesiveness may further be formed between the polarizer and the base film 110. [ A protective film or the like may be laminated on one surface or both surfaces of the polarizer.

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.

The second surface 122b of the prism 122 includes a plane 122b 'and a curved surface 122b ", which are connected to each other. The curved surface 122b " Is substantially the same as the prism according to an embodiment of the present invention except that it is formed adjacent to the apex T.

The curved surface 122b "is formed closer to the apex T of the prism than the plane 122b ', and the second surface 122b can satisfy the following equation 5 in its cross-section:

&Lt; EMI ID =

θ _{Rm2b "} <θ _{Rm2b '}

(In the formula 5, θ _Rm2b inclination angle at _"is R _m2b", θ _{Rm2b 'is} R _m2b' inclination angle at, R _{m2b "is} any point, R _{m2b 'of} the curved surface of the second side is the second Any point in the plane of the plane, R _{m2b "} and R _{m2b '} are different points). This shows a case where the second surface 121b has a concave shape when viewed from the inside of the prism. Therefore, the optical sheet may have a large effect of improving the viewing angle.

The curved surface 122b "increases in inclination angle from the point on the curved surface 122b" closest to T to the point on curved surface 122b "farthest from T. This is because when viewed from the inside of prism 122 And the curved surface 122b "is a concave curved surface. The radius of curvature of the curved surface 122b "may be 200 占 퐉 or less, specifically 50 占 퐉 to 100 占 퐉. In this range, a viewing angle improving effect may be obtained.

4, the plane 122b 'is shown as one plane, but the plane 122b' may be a polygonal plane having a plurality of planes.

The curved surface 122b "may be between 50% and less than 100%, particularly between 70% and 95% of the total area of the second surface 122b. 'May be more than 0% but not more than 50%, specifically, 5% to 30% of the total area of the second surface 122b. In this range, the workability is easy and the light diffusion control effect can be obtained.

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.

The 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.

The second surface 123b of the prism 123 includes a first plane 123b'a, a second plane 123b'b and a curved surface 123b ", and the curved surface 123b & 'a) and the second plane 123b'b.

And the second surface 123b is formed adjacent to the apex T of the prism in the order of the first plane 123b'a, the curved surface 123b ", and the second plane 123b'b, 6 can be satisfied:

&Lt; EMI ID =

? _{Rm3b'a &} lt _{;? Rm3b} ? _& lt _{;? Rm3b'b}

(In the formula 6, θ is the inclination angle of the _{Rm3b'a m3b'a} R, θ _{Rm3b "is} R _m3b" inclination angle at, θ is the inclination angle _Rm3b'b, R _m3b'a in R _m3b'b is the first _Rm3b'b is an arbitrary point in the second plane of the second surface, _{Rm3b "} is an arbitrary point in the curved surface of the second surface, _Rm3b'a , R _m3b'b , _{Rm3b "} are different). This shows a case where the second surface 121b has a concave shape when viewed from the inside of the prism. Therefore, the optical sheet may have a large effect of improving the viewing angle.

The curved surface 123b "may be a concave curved surface when viewed from the inside of the prism 123. The curved surface 123b" may have a curvature radius of 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.

Although the first plane 123b'a and the second plane 123b'b are shown as one plane in FIG. 5, the first plane 123b'a and the second plane 123b'b are formed in a plurality of planes Or may be a polygonal plane. The inclination angles in the first plane 123b'a and the second plane 123b'b are different from each other.

The curved surface 123b "may be 50% or more but less than 100%, particularly 70% to 95% of the total area of the second surface 123b. In this range, there may be a light diffusion effect. The total area of the second surface 123b'a and the second plane 123b'b may be greater than 0% and less than 50%, specifically 5% to 30% of the total area of the second surface 123b. , The workability is easy, and the light diffusion control effect can be obtained.

Although the first plane 123b'a and the second plane 123b'b are shown as one plane in FIG. 5, the first plane 123b'a and the second plane 123b'b are each a plurality of It may be a planar polygonal plane.

Hereinafter, an optical sheet according to another embodiment of the present invention will be described with reference to FIG. 6 is an enlarged sectional view of a prism in an optical sheet according to another embodiment of the present invention.

The 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. 6 instead of the prism of Fig. Hereinafter, only the prism of Fig. 6 will be described.

Referring to FIG. 6, the prism 124 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.

6, the first surface (122a) is a bottom of the apex of the prism 124 in a cross section of the prism 124 is T, the first surface (122a) of the prism (122) L _n, T and L _Let L _{m be} an arbitrary point existing between T and L _n in the first surface ₁₂₂ a of the prism connecting _n , and let nd 1 and L be a normal to the lower surface 110 a of the base film 110 passing through T. _n of the 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) passing through the The angle formed by the tangent line at L ₁ and the normal line nd 1 is θ _L1 , the angle formed by the tangent line at L _n in the first surface 122 a and the normal line ndn is θ _Ln , the tangent at L _m in the first surface ₁₂₂ a And the angle formed by the normal line ndm (hereinafter referred to as "tilt angle") is? _Lm , the following Equation 7 can be satisfied:

Equation (7)

? _L1 <? _Lm <? _Ln

By satisfying the above expression (7), 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. The curvature radius of the concave curved surface may be the same as or different from the curvature radius of the curved surface 121b "of the second surface 121b of the prism 124. [

In one embodiment, the first surface of the prism may include, in its cross-section, an area that satisfies the following equation (8): As a result, the effect of improving the viewing angle may be large.

<Formula 8>

? _Lm1 <? _Lm2

(In the formula 8, θ _Lm1 is the inclination angle of the L _m1, θ _Lm2 is the inclination angle of the L _m2, L _m1, L _m2 are arbitrary point present between the T and L _n, respectively, L _m1 is T than L _m2 Lt; / RTI &gt;

The prism 124 is formed such that the area of the first surface 122a that satisfies the formula 8 satisfies 90% or more of the entire area of the first surface 122a, specifically 95% to 100%, more specifically 90% to 95% . Within this range, there may be a light diffusion effect.

In one embodiment, the first surface of the prism satisfies the following formula (8-1) in the cross section, and the inclination angle increases from T to L _n , and as a result, the effect of improving the viewing angle may be greater:

<Formula 8-1>

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

(In the above formula 8-1, 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 equation 7, 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. 7 is an enlarged cross-sectional view of a prism in an optical sheet according to another embodiment of the present invention.

The 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. 7 instead of the prism of Fig. Hereinafter, only the prism of Fig. 7 will be described.

7, the prism 125 includes a first surface 123a and a second surface 121b, and the first surface 123a may satisfy Equation 9:

Equation (9)

θ _L1 > θ _Lm > θ _Ln

(In the above equation 9,? _L1 ,? _Lm ,? _Ln are respectively as defined in the above-mentioned formula 7).

This shows a case where the first surface 123a of the prism is a convex surface when viewed from inside the prism. The curvature radius of the convex curved surface may be the same as or different from the curvature radius of the curved surface 121b "of the second surface 121b of the prism 125. [

In one embodiment, the first side of the prism may include an area that satisfies Equation 10 in its cross-section: As a result, the effect of improving the viewing angle may be large:

<Formula 10>

? _Lm1 >? _Lm2

(In the above Equation 10 _{,? Lm1} and? _Lm2 are as defined in the above-mentioned Equation 8).

The prism 125 is formed such that the area of the first surface 123a that satisfies the formula 10 is 90% or more, specifically 95% to 100%, for example, 90% to 95% of the entire area of the first surface 123a. . Within this range, there may be a light diffusion effect.

In one embodiment, the first surface of the prism satisfies the following expression 10-1 in its cross-section, and the inclination angle decreases from T to L _n , and as a result, the viewing angle may be improved:

<Formula 10-1>

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

(In Formula 10-1 _{,? L1 ,? Lm1 ,? Lm2 ,? Lm3,? Ln} are as defined in Formula 8-1).

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 device according to an embodiment of the present invention will be described with reference to FIG. 8 is a schematic perspective view of a liquid crystal display device according to an embodiment of the present invention.

8, 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. 8 illustrates a case where the light source 1010 is disposed only on 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 one 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.

8, 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 prevents light emitted from the light guide plate 1020 from being scattered and allows most of light to be emitted at a light exit angle of 50 ° to 85 °, specifically 60 ° to 80 °, . 9, when it is assumed that a direction perpendicular to the light exit surface of the light guide plate 1020 (L2 in Fig. 9) (the front surface of the liquid crystal display device) is 0 deg., L2 and light exit The angle? Referring to FIG. 11, 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.

10, 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 may be a light exit surface, the side surface of the base layer 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. Fig. 10 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. 10 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. 8, the liquid crystal display 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.

Example 1: Production of optical sheet

Ultrasonic hardening resin was coated on the pull roll formed with a prismatic pattern. 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.

As shown in the following Table 1, the prism patterns of the engraved prisms are formed in such a manner that the light incidence surface is flat, the reflection surface is connected to one plane and one curved surface, and the curved surface is formed closer to the apex of the flat contrast prism pattern ). The radius of curvature of the reflective surface is 100 占 퐉, and the reflective surface has an area ratio of curved surface to planar surface of 7: 3. The inclination angle at an arbitrary point in the plane is 36.4 DEG, and the inclination angle at the point adjacent to the vertex of the prism pattern in the curved surface is 33.8 DEG. The reflecting surface has a concave shape when viewed from the inside of the prism pattern.

Example 2: Production of optical sheet

In Example 1, an optical sheet was produced in the same manner, except that an intaglio prismatic pattern having a concave curved light-incoming surface having the specifications of the following Table 1 was used in place of the prismatic pattern having a planar light-incidence plane.

Example 3: Production of optical sheet

In Example 1, an optical sheet was produced in the same manner, except that an intaglio prismatic pattern having a convex surface with a light-incoming surface having the specifications of the following Table 1 was used in place of the prismatic pattern having a planar light-incidence plane.

Comparative Example 1: Production of optical sheet

Ultrasonic hardening resin was coated on the pull roll formed with a prismatic pattern. 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.

As shown in Table 1 below, a prism pattern having a negative angle is a triangular prism pattern in which both the light incidence surface and the reflection surface are flat.

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

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 Prism width
(탆) 13 13 13 13 Prism height
(탆)  10  10  10  10 Incidence plane plane Concave surface Convex surface plane Curvature radius of light-entering surface
(탆) - 100 100 - Reflective surface One plane and one surface connected One plane and one surface connected One plane and one surface connected One plane Curvature radius of curved surface in reflective surface (탆) 100 100 100 - Surfaces of total reflection surface: Surface area ratio 7: 3 7: 3 7: 3 - The inclination angle at the point adjacent to the vertex of the curved surface of the reflecting surface
(°) 33.8 33.8 33.8 33.0 The inclination angle (占 in the plane of the reflecting surface) 36.4 36.4 36.4 33.0 θ _L1 (°) 33.0 29.6 36.4  33.0 θ _Ln (°) 33.0 36.4 29.6  33.0 θ _R1 (°) 29.6 29.6 29.6  33.0 θ _Rn (°) 36.4 36.4 36.4  33.0 the relationship of? _L1 ,? _R1 , and? _Rn ? _R1 <? _L1 <? _Rn ? _R1 =? _L1 <? _Rn θ _R1 < θ _L1
=? _Rn ? _R1 =? _L1 =? _Rn The relationship of? _R1 ,? _Rm ,? _Rn ? _R1 <? _Rm <? _Rn ? _R1 <? _Rm <? _Rn ? _R1 <? _Rm <? _{Rn R1} = θ _m θ = θR _Rn the relationship of? _L1 ,? _Lm ,? _Ln ? _L1 =? _Lm =? _Ln ? _L1 <? _Lm <? _Ln θ _L1 > θ _Lm > θ _Ln ? _L1 =? _Lm =? _Ln 1/2 Viewing Angle
(°)   35.9  36.1  33.8 27.3

As shown in Table 1, the optical sheet according to the present embodiment did not decrease the light-condensing efficiency and thus had a high optical efficiency and a wider viewing angle of 1/2, thereby improving the viewing angle.

On the other hand, as shown in Table 1, Comparative Example 1 in which the light incidence surface and the reflection surface are both planar and has a triangular cross section has a narrow viewing angle compared to 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 (19)

And a prism portion including a base film and a plurality of prisms formed on a lower surface of the base film,
The prism portion is a light incidence surface,
Wherein the prism includes a first surface and a second surface formed adjacent to the first surface,
Wherein the second surface comprises a plane and a curved surface,
Wherein the prism has a vertex of the prism as T, a low point of the second surface as R _n , an arbitrary point existing in the curved surface of the second surface connecting T and R _n as R _m , the normal to the lower surface of the base film to 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 through the ndn, R _m ndm An angle formed by the first surface and the normal line nd1 is θ _L1 , an angle formed by the tangent line at T and the normal line nd1 of the second surface is θ _R1 , an angle formed by the tangent line at R _n and the normal line ndn the θ _Rn, wherein the first one of the tangential and normal ndm the forming of the imprinted inclination angle θ R _m of the second surface when said _Rm, satisfy the following formula 1 and formula 2, the optical sheet:
<Formula 1>
θ _R1 ≤ θ _L1 ≤ θ _Rn
(only, θ _R1 ≠ θ _L1 ≠ θ _Rn )
<Formula 2>
? _R1 <? _Rm <? _Rn . A base film and a plurality of prisms formed on a lower surface of the base film, wherein the prism includes a first surface and a second surface formed adjacent to the first surface, and the second surface is a flat surface and a curved surface under,
Wherein an angle of view of 1/2 or more is 30 degrees or more with respect to light that is 50% or more of the light outgoing angle of 50 to 85 out of the total light outgoing angles. 3. The apparatus of claim 2, wherein the prism In the cross section of the prism, a vertex of the prism is T, a low point of the second surface is R _n , and an arbitrary point existing in the curved surface among the second surfaces connecting T and R _n is R _m , T wherein the normal to the lower surface of the base film to the normal to the lower surface of the base film to the normal to the lower surface of the base film through the nd1, R _n through the ndn, R _m ndm, passing An angle formed by the first surface and the normal line nd1 is θ _L1 , an angle formed by the tangent line at T and the normal line nd1 in the second surface is θ _R1 , an angle formed by the tangent at the line R _n and the normal line ndn is θ _Rn , And an inclination angle formed by a tangent line at R _m and a normal line ndm in the second surface is θ _Rm , the following formula 1 and formula 2 are satisfied:
<Formula 1>
θ _R1 ≤ θ _L1 ≤ θ _Rn
(only, θ _R1 ≠ θ _L1 ≠ θ _Rn )
<Formula 2>
? _R1 <? _Rm <? _Rn . The optical sheet according to any one of claims 1 to 3, wherein the curved surface is a concave curved surface when viewed from inside the prism. The optical sheet according to any one of claims 1 to 3, wherein the curved surface of the total area of the second surface is 50% or more and less than 100% and the plane is more than 0% and 50% or less. The optical sheet according to claim 1 or 3, wherein the prism has an angle? _Rn -? _R1 of 1 to 20 degrees. The optical sheet according to any one of claims 1 to 3, 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 °. The optical sheet according to claim 1 or 3, wherein the prism has an aspect ratio of 0.6 or more. The optical sheet according to claim 1 or 3, wherein the first surface is planar. The optical sheet according to claim 9, wherein the light incidence surface comprises a plurality of planes in the form of a polygonal surface. The optical sheet according to claim 1 or 3, wherein the first surface is a curved surface. 12. The method of claim 11, wherein when said first side of the trough L _n, would gradually from T to L _n larger the inclination angle, the optical sheet. 12. The method of claim 11, wherein when said first face of a bottom _n L, in which it gets smaller at the inclination angle T to L _n, the optical sheet. The optical sheet according to claim 1 or 3, wherein the first surface is a light incidence surface and the second surface is a reflective surface. The optical sheet according to claim 1 or 3, wherein the first surface has the same shape as the second surface. The optical sheet according to claim 1 or 3, wherein a polarizer is further laminated on the upper surface of the base film. A light source, a light guide plate formed adjacent to the light source, and an optical sheet according to claim 1 or 2 formed on an upper surface of the light guide plate,
Wherein the light guide plate and the prism of the optical sheet are opposed to each other. 18. The liquid crystal display device according to claim 17, wherein the light guide plate emits light having 50% or more of the total light exit angle at a light exit angle of 50 to 85 degrees. The liquid crystal display according to claim 18, wherein the liquid crystal display device has a half viewing angle of 30 to 45 degrees.

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