KR101522242B1 - Optical sheet and liquid crystal display including the same - Google Patents

Abstract

An optical sheet capable of increasing a viewing angle of a liquid crystal display by increasing light distribution characteristics and a liquid crystal display including the same are provided. The optical sheet is formed such that a first light-condensing film having a first prism pattern having a first refractive index and a second prism pattern having a second refractive index are formed so as to overlap and correspond to the first prism pattern, And a second light-condensing film repeatedly formed by grouping at least two prisms formed at different angles of vertices.

Description

TECHNICAL FIELD [0001] The present invention relates to an optical sheet and a liquid crystal display (LCD)

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical sheet, and more particularly to an optical sheet capable of widening a viewing angle of a liquid crystal display by changing the internal pattern structure of the optical sheet and a liquid crystal display including the same.

Of flat panel display devices, liquid crystal display devices are widely used today because they have advantages of miniaturization, light weight, thinness, and low power driving. Particularly, a liquid crystal display device using a thin film transistor can realize high quality, large size, and coloring of a display screen, and recently it has been used variously in various fields as well as a notebook PC and a monitor.

A typical liquid crystal display device is a device that visually converts a change in optical properties such as birefringence characteristics of a liquid crystal cell that emits light by applying a voltage to a specific molecular array of a liquid crystal to convert it into another molecular array, Is a light-receiving type display device that displays information using modulation of light by a light source.

Since such a liquid crystal display device is a light receiving type device, it includes a backlight unit for providing light to express an image, and the backlight unit is divided into a direct type and an edge type according to the arrangement of the light sources .

Further, the backlight unit of the liquid crystal display device includes an optical sheet made of a prism sheet or the like in order to improve optical characteristics of light emitted from the light source, for example, luminance uniformity and front luminance.

FIG. 1 is an exploded perspective view of a conventional liquid crystal display, FIG. 2 is a sectional view taken along a line II-II 'in FIG. 1, and FIG. 3 is an enlarged view of a portion A in FIG.

Referring to the drawings, a liquid crystal display device 1 includes a liquid crystal panel 10 and a backlight unit 20.

The liquid crystal panel 10 displays an image according to an external operation signal and a control signal. The liquid crystal panel 10 includes an array substrate 11 and a color filter substrate 13 opposed thereto and a liquid crystal layer (not shown) interposed between the two substrates, and these are the same as known configurations.

The backlight unit 20 is disposed on the back surface of the liquid crystal panel 10 and irradiates light to the back surface of the liquid crystal panel 10. [ The backlight unit 20 includes an optical sheet 21, a light source 25, a light guide plate 23, and a reflective sheet 27.

As the light source 25, a point light source such as a light emitting diode (LED) is used. A plurality of the light sources 25 may be arranged on at least one side of the light guide plate 23. Also, a cold cathode fluorescent lamp or an external electrode fluorescent lamp may be used as the light source 25.

The light guide plate 23 guides the light emitted from the light source 25 and exits toward the back surface of the liquid crystal panel 10. [ The light guide plate 23 may be made of a transparent resin such as polymethyl methacrylate (PMMA) or polycarbonate.

On the upper surface of the light guide plate 23, a plurality of patterns are formed in the longitudinal direction of the light guide plate 23, for example, in a direction perpendicular to the arrangement direction of the light sources 25. This pattern allows the light incident on the side surface of the light guide plate 23, that is, the light incidence surface, to diffuse and exit to the upper surface of the light guide plate 23, that is, the light exiting surface. In addition, a plurality of patterns are formed on the upper surface of the light guide plate 23, so that they can be used in combination with the optical sheet 21 to be described later.

The reflective sheet 27 is disposed opposite to the back surface of the light guide plate 23 and reflects light leaking to the back surface of the light guide plate 23 and enters the light guide plate 23 again. The reflective sheet 27 may be formed by coating silver (Ag) on base materials such as SUS, BRASS, aluminum, and PET, or by coating titanium (Ti) to prevent damage due to heat absorption.

The optical sheet 21 is disposed between the light guide plate 23 and the liquid crystal panel 10 to condense the light emitted from the light exit surface of the light guide plate 23 and output it to the liquid crystal panel 10.

The optical sheet 21 includes a condensing pattern 31 and 33 having a double structure composed of materials having different refractive indexes and a supporting layer 35 disposed on the condensing patterns 31 and 33.

The first and second prism patterns 31 and 33 are composed of a first prism pattern 31 and a second prism pattern 33 having different refractive indices and the first prism pattern 31 and the second prism pattern 33 are formed in the same direction And a plurality of linear prisms formed in parallel to each other. The light a emitted from the light guide plate 23 by the linear prism is refracted at least twice while passing through the linear prisms of the first prism pattern 31 and the second prism pattern 33 and is totally reflected and emitted.

Here, the outgoing angle of the light a emitted from the optical sheet 21, that is, the total reflection angle? 2 by the light-collecting patterns 31 and 33 is calculated from the light- ), The refractive indices n1 and n2 of the first prism pattern 31 and the second prism pattern 33 and the vertex angles alpha, beta and gamma of the linear prisms constituting the second prism pattern 33 Can be defined as the following equation.

[Mathematical Expression]

However, in the conventional optical sheet 21, since the total reflection angle 2 of the light a is substantially equal to the normal direction Y of the optical sheet 21, the optical sheet 21 The light a emitted through the liquid crystal panel 10 is incident on the back surface of the liquid crystal panel 10 substantially perpendicularly.

Accordingly, in the conventional liquid crystal display device 1, the viewing angle is narrowed by the light a in the vertical direction provided from the optical sheet 21. This is because the user can see the liquid crystal display device 1 in a different direction The color reversal or the difference in contrast is visually displayed on the screen, thereby causing inconvenience to the user.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical sheet capable of widening a viewing angle of a liquid crystal display device by changing the shape of a prism pattern of an optical sheet to adjust a total reflection angle and a liquid crystal display device including the same.

According to an aspect of the present invention, there is provided an optical sheet comprising: a first prism pattern having a first prism pattern having a first refractive index; a second prism pattern having a second refractive index; And the second prism pattern includes a second light-condensing film repeatedly formed by grouping at least two prisms formed at different angles of corresponding vertices.

According to an aspect of the present invention, there is provided a liquid crystal display device including: a liquid crystal panel; a light source disposed along at least one side of the light guide plate to emit light to the light entrance surface of the light guide plate; And an optical sheet arranged to collect the light emitted from the light source through the light guide plate and to provide the light to the back surface of the liquid crystal panel.

According to the optical sheet of the present invention and the liquid crystal display device including the optical sheet, the prism pattern of the light converging film is repeatedly formed by grouping at least two or more prisms formed at different angles of vertices corresponding to each other, The characteristics can be increased. The viewing angle of the liquid crystal display device can be widened according to the increase of the distribution characteristic of the light.

1 is an exploded perspective view of a conventional liquid crystal display device.
Fig. 2 is a cross-sectional view of Fig. 1 taken along line II-II '.
3 is an enlarged view of a portion A in Fig.
4 is a perspective view of an optical sheet according to the first embodiment of the present invention.
5 is a cross-sectional view of the optical sheet of Fig. 4 taken along line V-V '.
6 is a perspective view of an optical sheet according to a second embodiment of the present invention.
FIG. 7 is a cross-sectional view of the optical sheet of FIG. 6 taken along line VII-VII '.
8 is a graph showing light distribution characteristics of a liquid crystal display device according to the optical sheet of the present invention.
9 is a view showing a manufacturing process of an optical sheet according to the present invention.

Hereinafter, an optical sheet and a liquid crystal display device including the optical sheet according to the present invention will be described in detail with reference to the accompanying drawings. The remaining components of the liquid crystal display device except for the optical sheet according to the present invention are substantially the same as those described above with reference to FIG. 1, and therefore, the description will be made with reference to FIG.

4 is a perspective view of an optical sheet according to the first embodiment of the present invention.

1 and 4, an optical sheet 100 according to a first embodiment of the present invention includes a first light-collecting film 110 and a second light-collecting film 120 having different refractive indices, And a support film 130 positioned on the upper surface of the substrate 120.

The optical sheet 100 may be disposed between the light guide plate 23 and the liquid crystal panel 10 to condense the light provided from the light source 25 through the light guide plate 23 onto the back surface of the liquid crystal panel 10 and emit the light.

A prism pattern composed of a plurality of prisms may be formed on each of the first and second light-condensing films 110 and 120. The prism patterns formed on the first and second light-condensing films 110 and 120 may overlap each other. Here, the plurality of prisms constituting the prism pattern of each light converging film may have a triangular shape in its vertical section.

The prism pattern formed on the first light-condensing film 110 and the prism pattern formed on the second light-condensing film 120 may be formed in parallel with each other in the same direction. For example, the prism patterns formed on the first and second light-condensing films 110 and 120 may be formed in a direction parallel to the arrangement direction of the light sources 25 disposed on one side of the light guide plate 23.

A pattern may be formed on the upper surface of the light guide plate 23 and a pattern on the upper surface of the light guide plate 23 may be formed in a direction crossing the prism patterns formed on the first light focusing film 110 and the second light focusing film 120 . In other words, the pattern formed on the upper surface of the light guide plate 23 may be formed in a direction perpendicular to the direction in which the light source 25 is disposed.

The prism pattern of the first light-condensing film 110 and the prism pattern of the second light-condensing film 120 may have different refractive indices. For example, the refractive index of the prism pattern of the first light-condensing film 110 may be lower than the refractive index of the prism pattern of the second light-condensing film 120.

The prism pattern of the first light collecting film 110 may have a refractive index of about 1.3 to 1.9 and the prism pattern of the second light focusing film 120 may have a refractive index of about 1.5 to 2.0, May be approximately 0.1 to 0.2.

On the other hand, at least two or more prisms are bundled to form one group, and the group is repeated to form a prism pattern. For example, the group of the first prism 121 and the second prism 123 may be repeated to form a prism pattern.

Each of the first prism 121 and the second prism 123 of the second light-converging film 120 may have a triangular shape having three vertices. The three vertexes of the first prism 121 and the second prism 123 have different vertexes corresponding to each other, that is, angles (? 1,? 2,? 1,? 2,? 1,? 2) .

More specifically, the first vertex of the first prism 121 is formed at an angle? 1 of about 45 to 50 °, and the corresponding first vertex of the second prism 123 is about 60 to 65 2 of the angle? 2.

The first vertex angles? 1 and? 2 of the first prism 121 and the second prism 123 are set such that the prism of each prism and the prism of the first light-condensing film 110 adjacent thereto, .

The second vertex of the first prism 121 is formed at an angle beta 1 of about 60 to 65 degrees and the corresponding second vertex of the second prism 123 is formed at an angle beta 2 ).

The second vertex angles beta 1 and beta 2 of the first prism 121 and the second prism 123 are set such that the prism of each prism and the prism of the first light condensing film 110 adjacent thereto and the back surface of the supporting film 130 .

The third vertex of the first prism 121 and the third vertex of the second prism 123 may be formed to have angles? 1 and? 2 of approximately 65 to 70 degrees.

The third vertex angles gamma 1 and gamma 2 of the first prism 121 and the second prism 123 may be angles formed by the respective prisms and the two prisms of the first condensing film 110 adjacent thereto.

In this way, in the second light-condensing film 120 of the optical sheet 100 according to the present embodiment, at least two vertexes of the first prism 121 and the second prism 123, The light from the light guide plate 23 is guided by the first prism 121 and the second prism 123 of the second light focusing film 120 at a predetermined angle from the vertical direction of the optical sheet 100 It can be slanted. This will be described in more detail with reference to later drawings.

The support film 130 may be positioned on the upper surface of the second light collecting film 120 to support the first light focusing film 110 and the second light focusing film 120. The support film 130 may be formed of a transparent material having a predetermined thickness, and the thickness thereof may be one of 100um, 125um, 188um, and 259um.

The optical sheet 100 composed of the first light focusing film 110, the second light focusing film 120 and the support film 130 may be positioned between the light guide plate 23 and the liquid crystal panel 10, 23, the path of the light emitted from the light source 25 can be changed to the direction of the liquid crystal panel 10 and emitted.

Since the refractive indexes of the prism patterns formed on the first and second light-condensing films 110 and 120 of the optical sheet 100 are different from each other, the light emitted from the light- And can be refracted at least twice and condensed.

In other words, the light emitted from the light source 25 to the upper surface of the light guide plate 23 may be refracted while being incident on the prism pattern of the first light-condensing film 110 having a refractive index higher than that of the air layer. The light may be refracted and focused while being incident on the prism pattern of the second light-condensing film 120 having a refractive index higher than that of the prism pattern of the first light-condensing film 110. The light refracted by the prism pattern of the second light-condensing film 120 may be totally reflected on the inclined surface of the prism pattern and incident on the back surface of the liquid crystal panel 10.

5 is a cross-sectional view of the optical sheet of Fig. 4 taken along line V-V '.

Referring to FIGS. 4 and 5, the second light-converging film 120 may include a prism pattern composed of a plurality of prisms formed by repeatedly grouping at least two prisms as described above.

In other words, the first prism 121 and the second prism 123 form a group of the second light-condensing film 120, and the group is repeatedly formed to form a prism pattern. In the drawing, one first prism 121 and one second prism 123 are formed as one group, but the present invention is not limited thereto. For example, a plurality of first prisms 121 and a plurality of second prisms 123 may be repeatedly formed as one group, and the order of repeating the prisms in the group is not limited.

As described above, the corresponding vertexes of the first prism 121 and the second prism 123 may be formed to have different angles? 1,? 2,? 1,? 2,? 1,? 2, respectively. Accordingly, the angle? 2 'at which the light (a) is totally reflected on the opposed surface of the first prism 121 and the angle? 2' on which the light (b) is totally reflected on the opposed surface of the second prism 123 are different .

Here, the opposed surface of the first prism 121 is an inclined surface formed by a line connecting the second vertex and the third vertex of the first prism 121, and the opposed surface of the second prism 123 is the second prism 123 And the second vertex of the second vertex may be a slope formed by a line connecting the second vertex and the third vertex.

The first light a emitted from the light guide plate 23 passes through the air layer between the light guide plate 23 and the optical sheet 100 and passes through the first light focusing film 110 of the optical sheet 100, That is, the first incidence angle? 1, through the lower surface of the prism pattern formed on the first light-condensing film 110. The incident angle?

The first light a incident on the first condensing film 110 may be refracted once on the incident surface of the first condensing film 110 and proceed inside the prism pattern of the first condensing film 110.

The first light a traveling in the prism pattern of the first light converging film 110 is further refracted at the incident surface of the first prism 121 of the second light converging film 120, Lt; / RTI > Here, the incident surface of the first prism 121 may be an inclined surface formed by a line connecting the first vertex and the third vertex of the first prism 121.

The first light a propagated in the first prism 121 may be totally reflected at a predetermined angle, that is, the first total angle of? 1 'on the opposed surface of the first prism 121. The totalized first light a can be emitted to the outside of the optical sheet 100 through the support film 130. [ Here, the first light 'a' may be outputted obliquely from the normal direction Y of the optical sheet 100 in accordance with the first total square angle '1'.

In other words, the first light 'a' is totally reflected on the opposite surface of the first prism 121, and is separated from the normal direction Y of the optical sheet 100 by the first total angle of theta 1 ' The light can be totally reflected in the direction in which the light is emitted.

The second light b emitted from the light guide plate 23 passes through the air layer between the light guide plate 23 and the optical sheet 100 to be incident on the incident surface of the first light focusing film 110 of the optical sheet 100 2 incidence angle [theta] 2.

The second light b incident on the first light focusing film 110 may be refracted once on the incident surface of the first light focusing film 110 and proceed inside the prism pattern of the first light focusing film 110.

The second light b traveling to the inside of the prism pattern of the first light converging film 110 is further refracted at the incident surface of the second prism 123 of the second light converging film 120, Lt; / RTI > Here, the incident surface of the second prism 123 may be an inclined surface formed by a line connecting the first vertex and the third vertex of the second prism 123.

The second light b traveling in the second prism 123 may be totally reflected by the second total reflection angle? 2 'on the opposite surface of the second prism 123. The totalized second light b can be emitted to the outside of the optical sheet 100 through the support film 130. Here, the second light 'b' may be outputted obliquely from the normal direction Y of the optical sheet 100 in accordance with the second total reflection angle θ2 '. For example, the second light' b ' 2 'from the normal direction Y of the first and second reflection mirrors 100 and 100, and may be outputted obliquely.

That is, in the optical sheet 100 according to the first embodiment of the present invention, at least two prisms adjacent to each other in the second light-condensing film 120 may be grouped into a prism pattern so that the group is repeated . At this time, since the vertexes of the prisms forming the group are formed at different angles, the light provided to the optical sheet 100 is reflected at the opposite total reflection angle on the opposite surface of the second light-condensing film 120, The light distribution characteristic of the light source 100 can be increased. Thus, when the light distribution characteristic of the optical sheet 100 is increased, the viewing angle of the liquid crystal display device can be widened.

FIG. 6 is a perspective view of an optical sheet according to a second embodiment of the present invention, and FIG. 7 is a cross-sectional view of the optical sheet of FIG. 6 taken along line VII-VII '.

In the present embodiment, the second light-converging film 220 is formed in accordance with the first embodiment of the present invention described above with reference to FIG. 4, except that at least three prisms include a prism pattern formed repeatedly in one group Is the same as that of the optical sheet 100. [

1 and 6, the optical sheet 200 according to the present embodiment includes a first light-collecting film 210, a second light-collecting film 220, and a second light-collecting film 220 having different refractive indices And a support film 230 for supporting and supporting them. Here, the refractive index of the first light-collecting film 210 may be lower than that of the second light-collecting film 220, and the difference between the two refractive indices may be about 0.1 to 0.2.

The first light-condensing film 210 and the second light-condensing film 220 may have a prism pattern formed of a plurality of prisms on the surfaces corresponding to each other, and the prism patterns of the two films may overlap each other. The prism pattern of the first light-condensing film 210 and the prism pattern of the second light-condensing film 220 may be formed in parallel with each other in the same direction.

The prism pattern of the second light collecting film 220 includes at least three prisms adjacent to each other, for example, a first prism 221, a second prism 223, and a third prism 225, Can be formed repeatedly. Although the first prism 221, the second prism 223, and the third prism 225 are formed as a group in the drawing, the present invention is not limited thereto. For example, a plurality of first prisms 221, second prisms 223, and third prisms 225 may be repeatedly formed as a group, and the order of repeating the prisms in the group is not limited.

Each of the first prism 221, the second prism 223 and the third prism 225 of the second light collecting film 220 may be formed in a triangular shape having three vertexes. The three vertexes of the first prism 221, the second prism 223 and the third prism 225 have vertex angles? 1 to? 3,? 1 to? 3, and? 1 to? 3, .

More specifically, the first vertex of the first prism 221 is formed at an angle? 1 of approximately 45 to 50 °, and the corresponding first vertex of the second prism 223 is approximately 50 to 55 And the first vertex of the third prism 225 corresponding to the first prism 225 may be formed at an angle [alpha] 3 of about 60 to 65 [deg.].

The first vertex angles? 1 to? 3 of the first prism 221, the second prism 223 and the third prism 225 correspond to the respective prisms and the prism of the first light- May be an angle formed with the back surface of the film (230).

The second vertex of the first prism 221 is formed at an angle beta 1 of about 60 to 65 degrees and the second vertex of the corresponding second prism 223 is formed at an angle beta 2 And the second vertex of the third prism 225 corresponding to the second prism 225 may be formed at an angle beta 3 of about 45 to 50 degrees.

The second vertex angles beta 1 to beta 3 of the first prism 221, the second prism 223 and the third prism 225 are set such that the prisms of the prism and the prism of the first light- May be an angle formed with the back surface of the film (230).

The third vertex of the first prism 221, the third vertex of the second prism 223 and the third vertex of the third prism 225 corresponding to each other have angles? 1 to? 3 of about 65 to 70 degrees As shown in Fig.

The third vertex angles gamma 1 through gamma 3 of the first prism 221, the second prism 223 and the third prism 225 are set such that the two prisms of the prism and the first condensing film 210 adjacent thereto, .

In this way, in the second light-converging film 220 of the optical sheet 20 according to the present embodiment, at least two vertices corresponding to the first prism 221 to the third prism 225 forming the group are formed to have different angles The light provided from the light guide plate 23 can be outputted obliquely at a predetermined angle from the normal direction Y of the optical sheet 200 in the vertical direction. At this time, the light provided from the light guide plate 23 is refracted at least twice in the interior of the optical sheet 200, that is, in the prism patterns of the first and second light-condensing films 210 and 220, And can be emitted to the outside through the inclined surface of the prism pattern of the film 220.

6 and 7, the first light a emitted from the light guide plate 23 passes through the air layer between the light guide plate 23 and the optical sheet 200, 1 incident on the incident surface of the light collecting film 210, that is, the lower portion of the prism pattern formed on the first light collecting film 210.

The first light a incident on the first light collecting film 210 may be refracted once on the incident surface of the first light collecting film 210 and proceed inside the prism pattern of the first light focusing film 210.

The first light a propagated to the inside of the prism pattern of the first light focusing film 210 is further refracted at the incident surface of the first prism 221 of the second light focusing film 220 and is refracted into the first prism 221 Can proceed. Here, the incident surface of the first prism 221 may be an inclined surface formed by a line connecting the first vertex and the third vertex of the first prism 221.

The first light a traveling in the first prism 221 may be totally reflected by the first total angle of incidence? 1 'on the opposed surface of the first prism 221. The totalized first light a can be emitted to the outside of the optical sheet 200 through the support film 230. Here, the opposite surface of the first prism 221 may be an inclined surface formed by a line connecting the second vertex and the third vertex of the first prism 221.

On the other hand, the first light 'a' may be outputted obliquely from the normal Y of the optical sheet 200 according to the first total angle of incidence 1 ' Can be totally reflected in a direction separated by an angle of the first total angle of incidence (? 1 ') from the light source (Y), and can be outputted obliquely.

The second light b and the third light c emitted from the light guide plate 23 are transmitted through the air layer between the light guide plate 23 and the optical sheet 200 through the first light focusing film 210 at a second incident angle? 2 and a third incident angle? 3.

The second light beam b and the third light beam c incident on the first light focusing film 210 are respectively refracted once on the incident surface of the first light focusing film 210, It can proceed inside the pattern.

The second light b traveling to the inside of the prism pattern of the first light collecting film 210 is further refracted at the incident surface of the second prism 223 of the prism pattern of the second light converging film 220, ). ≪ / RTI > The third light c traveling to the inside of the prism pattern of the first light focusing film 210 is further refracted at the incident surface of the third prism 225 of the prism pattern of the second light focusing film 220, (Not shown).

The incident surface of each of the second prism 223 and the third prism 225 is inclined to the inclined surface connecting the first vertex and the third vertex of the second prism 223 and the first vertex of the third prism 225, And may be a slope connecting the vertexes.

The second light b propagating in the second prism 223 is totally reflected by the second total reflection angle? 2 'from the opposite surface of the second prism 223 to the optical sheet 200 And the like. The third light c traveling to the inside of the third prism 225 is totally reflected by the third total square angle 3 'from the opposite surface of the third prism 225, (Not shown). The opposing surfaces of the second prism 223 and the third prism 225 are inclined surfaces connecting the second vertex and the third vertex of the second prism 223 and the second vertex of the third prism 225, And may be a slope connecting the third vertices.

On the other hand, the second light 'b' may be totally reflected in a direction away from the normal Y of the optical sheet 200 by an angle corresponding to the second total reflection angle? 2 ', and may be outputted obliquely. The third light c may be totally reflected in a direction away from the normal Y of the optical sheet 200 by an angle of the third total angle of view? 3 ', and may be outputted obliquely.

Here, the second total reflection angle? 2 'of the second light (b) may be substantially the same as the normal direction Y of the optical sheet 200 in the vertical direction. Accordingly, the optical sheet 200 according to the present embodiment can increase optical characteristics in the vertical direction of the optical sheet 200 by the second prism 223 of the second light-condensing film 220.

That is, in the optical sheet 200 according to the second embodiment of the present invention, at least three prisms adjacent to each other in the second light-condensing film 220 are grouped into a group, and a prism pattern is formed so that the groups are repeated . At this time, the angle formed by the vertexes of the three prisms constituting the group are different from each other, so that the light provided to the optical sheet 200 is reflected at the opposite total reflection angle on the opposite surface of the second light-condensing film 220 The light distribution characteristic of the optical sheet 200 can be increased, and thus the viewing angle of the liquid crystal display device can be widened.

At least one of the three prisms of the second light-condensing film 220 may totally reflect light in the vertical direction of the optical sheet 200, thereby increasing the optical characteristics in the vertical direction.

8 is a graph showing light distribution characteristics of a liquid crystal display device according to the optical sheet of the present invention. In the graph, the x-axis represents the viewing angle, and the y-axis represents the luminance value.

Referring to FIG. 8, it can be seen that the liquid crystal display device to which the optical sheets 100 and 200 according to the present invention shown in FIGS. 4 to 7 are applied increases the light distribution characteristic as compared with the conventional liquid crystal display device. Accordingly, a liquid crystal display device to which the optical sheets 100 and 200 according to the present invention are applied can have a wider viewing angle than a conventional liquid crystal display device.

9 is a view showing a manufacturing process of an optical sheet according to the present invention.

Hereinafter, a method of manufacturing an optical sheet according to the present invention will be described with reference to the drawings. For convenience of explanation, a method of manufacturing an optical sheet according to an embodiment of the present invention shown in FIG. 4 will be described.

Referring to Fig. 9, the apparatus for manufacturing the optical sheet 100 may include a cortical bottom, a pattern forming portion, and a curing portion.

The intellectual subdivision may include a first numerical bottom portion 220 and a second numerical bottom portion 270. The pattern forming unit may include a first pattern forming unit 230 and a second pattern forming unit 250. The curing unit may include a first curing unit 240, a second curing unit 260, and a third curing unit 280.

First, the support film 130 of the optical sheet 100 may be provided to the first male cadastral base 220 through the roller 210. The resin layer 220 may be formed by dropping the first resin 221 on the support film 130 to a predetermined thickness.

The supporting film 130 having the resin layer formed thereon can be moved to the first pattern forming part 230 by the roller 210. [ The first pattern forming unit 230 may form the first prism 121 of the second light condensing film 120 by pressing the resin layer using a mold roller. Here, the first pattern forming part 230 may leave the resin layer in the remaining area except the area where the first prism 121 is formed on the support film 130. [

The support film 130 on which the first prism 121 is formed is moved to the first curing unit 240 and the first prism 121 is first cured by ultraviolet light emitted from the first curing unit 240 have. At this time, a predetermined mask (not shown) may be used to harden only the first prism 121 of the resin layer or the entire resin layer may be lightly cured.

After the first prism 121 is cured, the support film 130 is moved to the second pattern forming part 250 by the roller 210, and the second pattern forming part 250 is moved The second prism 123 can be formed on the resin layer except for the first prism 121. In this case, Accordingly, the second light-condensing film 120 may be formed on the support film 130.

As described above, the second light-condensing film 120 includes a prism pattern formed by repeating groups of first prisms 121 and second prisms 123 having different angles of corresponding vertices can do.

The support film 130 having the prismatic pattern formed thereon is moved to the second cured portion 260 and the second cured portion 260 is irradiated with ultraviolet light irradiated from the second cured portion 260, ) Can be cured.

When the prism pattern of the second light-condensing film 120 is cured, the support film 130 on which the second light-condensing film 120 is formed can be moved to the second water- The second water dots 270 may be formed in the region between the first prism 121 and the second prism 123 in the valley region of the prism pattern of the second light- The first condensing film 110 having a plurality of prisms can be formed.

The plurality of prisms of the first light condensing film 110 are cured by the ultraviolet light irradiated from the third curing unit 280 and the first light condensing film 110, the second light condensing film 120, and the supporting film 130 ) Can be completed.

The distribution characteristics of light emitted through the optical sheet 100 can be increased by the first prism 121 and the second prism 123 formed on the second light-condensing film 120 of the optical sheet 100, The viewing angle of the liquid crystal display device in which the optical sheet 100 is used can be widened.

While a number of embodiments have been described in detail above, it should be construed as being illustrative of preferred embodiments rather than limiting the scope of the invention. Therefore, the invention should not be construed as limited to the embodiments described, but should be determined by equivalents to the appended claims and the claims.

100, 200: optical sheet 110, 210: first condensing film
120, 220: second condensing film 121, 221: first prism
123, 223: second prism 225: third prism
130, 230: Support film

Claims (16)

A first light-condensing film provided with a first prism pattern having a first refractive index; And
A second prism pattern having a second refractive index higher than the first refractive index is overlapped with the first prism pattern so that the second prism pattern overlaps at least two prisms in a group, And a second light-converging film having different angles of vertexes corresponding to each other,
And the second light-condensing film is located on the opposite side of the light incidence surface of the first light-condensing film. The method according to claim 1,
The second prism pattern may include a first prism and a second prism,
Wherein the first prism and the second prism have different angles of at least two vertices corresponding to each other. 3. The method of claim 2,
Wherein an angle of the first vertex of the first prism is 45 to 50 degrees and an angle of the first vertex of the second prism corresponding to the first vertex of the first prism is 60 to 65 degrees. 3. The method of claim 2,
Wherein an angle of a second vertex of the first prism is 60 to 65 degrees and an angle of a second vertex of the second prism corresponding to a second vertex of the first prism is 45 to 50 degrees. 3. The method of claim 2,
The light provided from the outside is totally reflected in a direction away from the normal line in the vertical direction by a first total reflection angle on the opposed surface of the first prism and reflected by the second total reflection angle from the normal direction on the opposed surface of the second prism . The method according to claim 1,
The second prism pattern is formed by repeating a group consisting of a first prism, a second prism, and a third prism,
Wherein the first prism, the second prism, and the third prism have different angles of at least two vertices corresponding to each other. The method according to claim 6,
Wherein the angle of the first vertex of the first prism is 45 to 50 degrees and the angle of the first vertex of the second prism corresponding to the first vertex of the first prism is 50 to 55 degrees, Wherein the angle of the first vertex and the angle of the first vertex of the third prism corresponding to the first vertex of the second prism is 60 to 65 degrees. The method according to claim 6,
Wherein the angle of the second vertex of the first prism is 60 to 65 degrees and the angle of the second vertex of the second prism corresponding to the second vertex of the first prism is 55 to 60 degrees, Wherein an angle of the second vertex of the third prism and a second vertex of the third prism corresponding to the second vertex of the second prism is 45 to 50 degrees. The method according to claim 6,
The light provided from the outside is totally reflected in a direction away from the normal line in the vertical direction by the first total reflection angle on the opposed surface of the first prism and is reflected by the second total reflection angle And is totally reflected in a direction away from the normal normal line by a third total reflection angle at an opposite surface of the third prism. The method according to claim 1,
Wherein the first prism pattern and the second prism pattern have the same height. The method according to claim 1,
And a support film disposed on the second light-condensing film and supporting the first light-condensing film and the second light-condensing film. A liquid crystal panel;
A light source disposed along at least one side of the light guide plate and emitting light to the light incident side of the light guide plate; And
And an optical sheet disposed between the light guide plate and the liquid crystal panel for condensing the light emitted from the light source through the light guide plate and providing the light to the back surface of the liquid crystal panel,
In the optical sheet,
A first light-condensing film provided with a first prism pattern having a first refractive index; And
A second prism pattern having a second refractive index higher than the first refractive index is overlapped with the first prism pattern so that the second prism pattern overlaps at least two prisms in a group, Converging film having different angles of vertexes corresponding to each other,
And the second light-condensing film is located on the opposite side of the light incidence surface of the first light-condensing film. 13. The method of claim 12,
Wherein the light guide plate includes a pattern on an upper surface thereof,
Wherein the pattern of the light guide plate and the first prism pattern and the second prism pattern of the optical sheet are different directions. 13. The method of claim 12,
Wherein the second prism pattern of the optical sheet has a first prism and a second prism repeated in a group,
Wherein the first prism and the second prism have different angles of at least two vertices corresponding to each other. 13. The method of claim 12,
Wherein the second prism pattern of the optical sheet is composed of a first prism, a second prism, and a third prism,
Wherein the first prism, the second prism, and the third prism have different angles of at least two vertices corresponding to each other. 13. The method of claim 12,
Wherein the first prism pattern and the second prism pattern have the same height.

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