KR101802579B1 - 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 that is composed of at least two planes of the polygonal shape, the apex of the prism T, connected to the low viscosity of the second side R _n, T, and R _n in a cross section of the prism is within the surface plane above through the nd1, R _n the normal to the lower surface of the base film to the point passing through the R _m, T is within, or T, and R _n and the other plane in the T and coplanar base film wherein the normal to the bottom surface is ndn, R _m of the base ndm the normal to the lower surface of the film, each of the first surface and the normal line nd1 forms through the containing θ _L1, T Day 2 of the surface The plane and the normal nd1 An inclination angle? _Rm is an angle formed by one plane of the second surface including angles θ _Rn and R _m consisting of one plane and the normal line ndn of the second plane including angles θ _R1 and R _n and the normal ndm An optical sheet satisfying Equation (1) and Equation (2) is provided, and a liquid crystal display including the optical sheet 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 two or more planes of a polygonal shape, wherein a vertex of the prism is T, a bottom point of the second surface is R _n , T and R _n the normal to the lower surface of the base film to the first point in the inside of the second side plane, and either in the T and the same plane, or T, and R _n and the other plane passing through the R _m, T nd1, R _n for connecting the A normal to the lower surface of the base film passing through R _m is ndn, a normal to the lower surface of the base film passing through R _m is ndm, and an angle formed by the first surface and the normal nd 1 is θ _L1 , T Among the second faces, If the normal nd1 is the angle is θ _R1, R _n is the first angle formed by a plane and the normal line ndn of the second surface including the one plane and the normal line ndm of the second surface including a θ _Rn, R _m forms When the engraving angle is? _Rm , the following equations 1 and 2 can be satisfied:

<Formula 1>

θ _R1 ≤ θ _L1 ≤ θ _Rn

(only, θ _R1 ≠ θ _L1 ≠ θ _Rn )

<Formula 2>

θ _R1 ≤ θ _Rm <θ _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 the light exit angle of the light guide plate.
8 is a perspective view of a light guide plate according to an embodiment of the present invention.
Fig. 9 shows the optical profile (x axis: light emission angle, y axis: relative intensity) 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 this specification, the inclination angles,? _Rn and? _Ln are all defined as angles formed outside the prism, and? _R1 and? _L1 are both defined as the angles formed inside the prism.

In the present specification, the term "tilt angle" in the second aspect means an angle formed by the normal to the lower surface of the base film of the prism passing through any point on the second surface of the prism and the plane including the point.

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.

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 two or more planes of a polygonal shape, wherein a vertex of the prism is T, a bottom point of the second surface is R _n , T and R _n the normal to the lower surface of the base film to the first point in the inside of the second side plane, and either in the T and the same plane, or T, and R _n and the other plane passing through the R _m, T nd1, R _n for connecting the A normal to the lower surface of the base film passing through R _m is ndn, a normal to the lower surface of the base film passing through R _m is ndm, and an angle formed by the first surface and the normal nd 1 is θ _L1 , T Among the second faces, If the normal nd1 is the angle is θ _R1, R _n is the first angle formed by a plane and the normal line ndn of the second surface including the one plane and the normal line ndm of the second surface including a θ _Rn, R _m forms When the engraving angle is? _Rm , the following equations 1 and 2 can be satisfied:

<Formula 1>

θ _R1 ≤ θ _L1 ≤ θ _Rn

(only, θ _R1 ≠ θ _L1 ≠ θ _Rn )

<Formula 2>

θ _R1 ≤ θ _Rm <θ _Rn

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.

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, Cyclic olefin (COP) based resin, acrylonitrile-butadiene-styrene copolymer resin, polyacrylonitrile-butadiene-styrene copolymer resin, 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 reflects the light from the first surface 121a and reflects the light to the base film 110. The second surface 121b may be formed of two or more planes of a polygonal shape. 2 shows a configuration in which the first plane 121b ', the second plane 121b' 'and the third plane 121b' ', which are the three planes of the second plane 121b are connected to each other, And two or more planes 121b may be 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 the first and in the second plane of the face (121b) T, and R _n and the lower surface (110a) of the other plane the second plane (121b "), the base film 110, which passes through the point R _m, T in the linking 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, the two first side (121a) and the normal nd1 is the angle angle of the first plane (121b ') and the normal nd1 of the second surface (121b) including a θ _L1, T forming agent comprising a θ _R1, R _n "each composed of a ( ') and the normal ndn second plane (121b of the second surface (121b) including a θ _Rn, R _m 2, a third plane 121b)," the surface (121b) a) with the normal line ndm the angle (Hereinafter, also referred to as "inclination angle") is? _Rm , Equation 2-1 can be satisfied:

<Formula 1>

θ _R1 ≤ θ _L1 ≤ θ _Rn

(only, θ _R1 ≠ θ _L1 ≠ θ _Rn)

<Formula 2-1>

? _R1 <? _Rm <? _Rn

This is the case where the second surface 121b of the prism 121 is concave when viewed from the inside of the prism. θ _R1 ≠ θ _L1 ≠ θ _Rn means that θ _R1, θ _L1 , θ _Rn are excluded. In the present specification, the term " point in a plane "means a point existing only in a plane except a point on a plane edge.

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.

Is formed adjacent to the apex T of the prism in the order of the first plane 121b ', the second plane 121b &quot;, and the third plane 121b "' in the prism 121, ', The second plane 121b'', and the third plane 121b'''. That is, the inclination angle measured from the plane forming the second surface increases from T to R _n on the second surface.

In one embodiment, the second surface 121b of the prism 121 may satisfy the following equation 3 in its cross section: Therefore, the prism may have a large effect of improving the viewing angle:

<Formula 3>

? _Rm1 <? _Rm2

(In the formula 3, θ _Rm1 is the inclination angle of the R _m1, θ _Rm2 is within the tilt angle, R _m1, R _m2 is present between the T and R _n and the second of the different surface planes each from R _m2, R _m1 is located adjacent to T than R _m2 ).

In one embodiment, the second surface of the prism satisfies Equation 3-1 on the cross section, 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>

θ _R1 <and and and <θ _{Rm1 <Rm2} θ <θ _Rm3 <and and and <θR _n

(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 low at the surface apex, R _n is the second prism, R _m1, R _m2, R _m3 is T and R _n is within any jeomyigo second different planes of the face existing between, R _m1, respectively, R _m2 , R _m3 ).

This means that when viewed from the inside of the prism, the second surface is concave.

The prism 121 may have the angle? _Rn -? _R1 of 1 to 20 degrees, specifically 3 to 15 degrees, more specifically 4 to 10 degrees. 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. .

1 shows a case where the second surface is formed by three planes 121b ', 121b'', and 121b'''. However, the second surface may consist of two planes, where R _m is T, and the prism can satisfy the following equations 1 and 2-2:

<Formula 1>

θ _R1 ≤ θ _L1 ≤ θ _Rn

(only, θ _R1 ≠ θ _L1 ≠ θ _Rn)

<Formula 2-2>

? _R1 =? _Rm <? _Rn

(In the above equations (1) and (2-2),? _R1 ,? _L1 ,? _Rn ,? _Rm are as defined in Equations (1) and (2-1).

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 be formed between the polarizer and the base film 110. A protective film or the like may be laminated on one side or both sides 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. 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 tangent of the of T the normal to the lower surface (110a) of the base film 110, ndn, the normal to the lower surface (110a) of the base film 110 through the L _m ndm, the first surface (122a) with the normal line of each nd1 the forms this angle is the tangent and normal ndn in L _n of θ _L1, the first surface (122a) forming the tangent and normal ndm of from L _m θ _Ln, the first surface (122a) forming each of (Hereinafter referred to as "tilt angle") is? _Lm , the following equation 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 radius of curvature of the first surface 122a 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 122, the first surface 122a may include a plane. For example, 95% or more and less than 100% of the total area of the first surface 122a is a curved surface, and more than 0% and 5% or less may be a flat surface.

In one embodiment, the first surface of the prism may include an area that satisfies the following equation 5 in its cross section: 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).

The prism 122 is formed such that the area of the first surface 122a that satisfies the formula 5 satisfies 90% or more of the total 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 expression 5-1 in its cross section, 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)).

This shows the case where the first surface 123a of the prism 123 is a convex surface when viewed from the inside of the prism. At this time, the radius of curvature of the first surface may be 200 占 퐉 or less, specifically 50 占 퐉 to 200 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 123, the first surface may include a plane. For example, 95% or more and less than 100% of the total area of the first surface is a curved surface, and more than 0% and 5% or less may be a flat surface.

In one embodiment, the first surface of the prism may include a region that satisfies Equation 7 in its cross section: 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 equation 5).

The prism 123 is formed such that the area of the first surface 123a that satisfies the formula 7 satisfies 90% or more of the total area of the first surface 123a, 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 7-1 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 7-1>

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

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

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, the prism pattern of a negative angle can be a polygonal surface in which the light incidence plane is plane and the reflection plane is connected to three planes. The first plane, the second plane, and the third plane, respectively, when the three planes constituting the reflective surface are referred to as a first plane, a second plane, and a third plane, respectively. The inclination angle in the first plane (θ _Rm1), the tilt angle in the second plane (θ _Rm2), the inclination angle (θ _Rm3) in the third plane is shown in Table 1 below. The reflecting surface shows a concave shape when viewed from the inside of the prism.

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 (탆) of the light- - 100 200         - Reflective surface Polygon face with three planes connected Polygon face with three planes connected Polygon face with three planes connected One plane ? _Rm1 (?) 30.8 30.8 30.8 33.0 θ _Rm2 (°) 33.1 33.1 33.1 33.0 ? _Rm3 (?) 35.3 35.3 35.3 33.0 θ _L1 (°) 33.0   30.8  33.7  33.0 θ _Ln (°) 33.0   35.3   30.3  33.0 θ _R1 (°)  30.8   30.8   30.8  33.0 θ _Rn (°)  35.3   35.3   35.3  33.0 the relationship of? _L1 ,? _R1 , and? _Rn ? _R1 <? _L1 <? _Rn ? _R1 =? _L1 <? _Rn ? _R1 <? _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
(°)   38.5  40.3  37.6 27.3

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

On the other hand, as shown in Table 1, 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.

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 three or more planes of a polygonal shape,
The apex of the prism in the cross section of the prism T, the first is within the second plane to a bottom of the second side connected to the R _n, T, and R _n plane or the T and the same plane, or T, and R _n and other a point in the plane R _m, 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 the normal to the lower surface ndm, the second to the first surface and the normal line nd1 is the angle angle of the second surface one plane and the normal line nd1 of containing θ _L1, T forms include θ _R1, R _n the second side each comprising a single plane and the normal line ndn of when it is imprinted inclination angle of a plane and a normal line ndm of the second surface including a θ _Rn, R _m forming θ _Rm, satisfies the following formula 1 and formula 2 Lt; RTI ID = 0.0 &gt; of:
<Formula 1>
θ _R1 ≤ θ _L1 ≤ θ _Rn
(only, θ _R1 ≠ θ _L1 ≠ θ _Rn)
<Formula 2>
θ _R1 ≤ θ _Rm <θ _Rn
Wherein the first surface is either a single plane or wherein it increases the inclination angle toward the first side of the trough L _n at T when the said L _n, the optical sheet. The optical sheet as claimed in claim 1, wherein the optical sheet has a half viewing angle of 30 ° or more with respect to light that is 50% or more of the total light output angle at a light output angle of 50 to 85 °. delete 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 the inclination angle of the R _m1, θ _Rm2 the inclination angle at the R _m2, R _m1, R _m2 is present between the T and R _n, and is within the second of the different flat surfaces, respectively, R _m1 is being positioned adjacent the T than R _m2). The optical sheet according to claim 4, wherein the second surface has a larger tilt 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 °. The optical sheet according to claim 1, wherein the prism has an aspect ratio of 0.6 or more. delete delete delete delete delete The optical sheet according to claim 1, wherein the first surface is a light incidence surface and the second surface is a reflective surface.  The optical sheet according to claim 1, wherein the first surface has the same shape as the second surface. The optical sheet according to claim 1, wherein a polarizer is further laminated on an upper surface of the base film. A light source, a light guide plate formed adjacent to the light source, and first, second, fourth, fifth, sixth, seventh, eighth, and 14th elements formed on the upper surface of the light guide plate. , The optical sheet according to any one of claims 15 to 16,
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 device according to claim 18, wherein the liquid crystal display device has a half viewing angle of 30 to 45 degrees.

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