KR20100048448A - Prism sheet - Google Patents

Abstract

PURPOSE: By magnifying the angle which disperses the incident light by using the pattern layer in which the lenticular pattern is mixed or lays eggs it broadens the viewing angle and the optical film can rise the masking property. CONSTITUTION: A pattern layer(200) has the configured surface in which a plurality of lenticular patterns is formed into the continuous phase. In the pattern layer, the lenticular pattern(202) in which two lenticular patterns is overlapped of form and single lenticular pattern(201) is mixed. As to the base material layer, the thickness is about 400μm to 10. The base material layer(100) the sheet which is to the transparent resin which is used for the prism sheet or the prism film.

Description

Optical film having a structured surface

The present invention relates to an optical film having a structured surface.

The backlight unit (BLU), which is widely used in liquid crystal displays, uses light sources such as Cold Cathode Fluorescent Lamps (CCFLs) to sequentially pass through the light guide plate, the light diffusion plate, and the prism sheet to the liquid crystal panel. To reach. The light emitted from the light source is transmitted to the front surface of the liquid crystal panel in a planar shape through the light guide plate, and the light source passed through the light guide plate can obtain a uniform light intensity across the entire screen through the light diffusion plate. The optical path control function is performed to convert the light beams in various directions through the diffusion sheet into the viewing angle range suitable for the viewer to recognize the image. In addition, the lower portion of the light guide plate is provided with a reflecting plate for increasing the use efficiency of the light source by allowing the light that is not delivered to the liquid crystal panel to be reflected back out of the path and used.

In addition, many kinds of plates or films are used so that the maximum amount of light generated from the light source can reach the liquid crystal device.

The light diffusion plate forms a uniformity of luminance of the light emitted from the light source lamp, and at the same time, serves to conceal the bright lines of the lamp. In addition, it serves as a support for the above various optical films. To this end, various light diffusing agents are added to the light diffusing plate, which causes light diffraction, scattering, reflection, and the like, and causes a diffusion effect.

In order to collect a large amount of light from the light diffusion plate to the front, a variety of materials including a light diffusion film, a prism film should be mounted. This multi-layered material raises the cost and lowers productivity. have.

On the other hand, the prism sheet plays an important role in improving luminance by controlling the light path so that light outside the viewing axis range is within the viewing axis range.

The prism sheet has a structure formed by repeating a plurality of three-dimensional patterns. For example, the three-dimensional pattern of a triangular cross-section is repeated to form a valley and a peak, so that the prism mountain can maximize the condensing effect to increase the front brightness. have.

However, as the front luminance is increased, the half-angle angle is relatively narrowed, and there is a problem in that the viewing angle characteristic is deteriorated, such as a cut-off phenomenon in which the luminance is suddenly lowered at a specific viewing angle. In addition, a bright line is visible due to the pattern, and a protective film was additionally used to conceal and compensate for the viewing angle.

In view of such a situation, Korean Patent Laid-Open Publication No. 2006-665871 discloses a backlight assembly capable of obtaining high luminance characteristics by forming a random microlens array on one surface of a prism sheet.

A perspective view of a prism sheet used herein is illustrated in FIG. 1, wherein the prism sheet includes a lens surface (ie, a pattern layer) on which a microlens array in which microlenses 21 are randomly arranged is formed on a substrate layer 10. In addition, the light incident on the lens surface is refracted in various directions, so that it is possible to obtain even optical characteristics over a wide range and to secure wide viewing angle characteristics. It is also described that when a lens is arranged in lenses having different sizes, a moire phenomenon, which is an optical phenomenon in which a pattern like a ripple is formed on a screen when two or more sheets of the same sheet are stacked, is described. .

However, when the micro lenses are randomly arranged, there may be a problem in that the bright lines are not sufficiently covered because the lenses and the lenses are spaced apart from each other, and there is also a problem that the luminance and the viewing angle are not sufficient.

The present invention is to provide an optical film that is excellent in the concealment against the bright line and wide viewing angle by forming a plurality of lenticular structure but a lenticular pattern of a single lenticular pattern and two lenticular patterns overlapping It is.

An object of the present invention is to provide an optical film having excellent concealability against bright lines and a wider viewing angle and improved brightness.

In one embodiment of the invention there is provided a patterned layer having a structured surface and composed of a transparent polymer composition; In an optical film comprising a flat surface of a pattern layer and an adjacent substrate layer, the pattern layer has a structured surface in which a plurality of lenticular patterns are formed in a continuous phase, wherein a single lenticular pattern and two lenticular patterns overlap Lenticular patterns are mixed, and the lenticular pattern in which two lenticular patterns overlap is drawn by drawing an imaginary circle along the cross-section along the vertex of each lenticular pattern, which is adjacent to the base layer. The radius of any of the lenticular patterns formed is R1, the radius of the lenticular pattern adjacent thereto is R2, and the line between the 1/2 diameter points where each pattern is formed adjacent to the base layer is L. In this regard, R1, R2, and L provide optical films satisfying the following Expressions 1 and 2.

Equation 1

5 μm <R1 or R2 <80 μm

Equation 2

R1-R2 | 〈L <(R1 + R2)

In the optical film according to an embodiment of the present invention, the lenticular pattern of the form in which two lenticular patterns are overlapped is formed by drawing a virtual circle along a cross section of an apex and tangentially adjacent the substrate layer. The inclination angle θ with the base layer may satisfy the following Equation 3.

Expression 3

90 ° <θ <180 °

In the optical film according to an embodiment of the present invention, R1 and R2 may be the same or different from each other.

In the optical film according to the embodiment of the present invention, the lenticular pattern of the form in which the two lenticular patterns overlap each other may be formed at a ratio of 50 to 95% of the total pattern layer area.

According to the exemplary embodiment of the present invention, by partially arranging the lenticular patterns in which two lenticular patterns are superposed on the pattern layer, it is possible to provide an optical film having improved concealment against bright lines and a wide viewing angle.

In addition, it is possible to provide an optical film that has no problem in exposing the function of the prism sheet by satisfactory brightness as well as the concealment of the bright line and the improvement of the viewing angle.

As a result, in the backlight optical sheet assembly, a protective film added for the concealment of the prism sheet and compensation of the viewing angle may be omitted, and thus the cost increase due to the use of the additional optical film may be suppressed and productivity may be improved.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

Typically an optical film comprising an optical structural surface consists of a base layer and a pattern layer, the pattern layer having a structured surface and of transparent polymer composition. In particular, the structuring generally has a structure in which a bone and a peak are repeated by forming a plurality of three-dimensional patterns repeatedly.

2 is a perspective view of an optical film according to the present invention, FIG. 3 is a sectional view, and FIG. 4 is a partially enlarged sectional view.

As shown in Figures 2 to 4, the optical film according to one embodiment of the present invention is composed of a base layer 100 and a pattern layer 200, the pattern layer is a single lenticular pattern 201 and two The lenticular pattern 202 has a structured surface in which two lenticular patterns overlap. In particular, in the pattern layer 200 of the optical film of the present invention, the lenticular pattern 202 in which two lenticular patterns overlap each other is formed by drawing an imaginary circle along a cross section of an axial point of each lenticular pattern. The radius of one lenticular pattern formed adjacent to the base material layer is set to R1, the radius of the lenticular pattern adjacent to this base material is set to R2, and a line is connected between the 1/2 diameter points formed adjacent to the base material layer. When L is R1, R2 and L are formed to satisfy the following equations (1) and (2).

Equation 1

5 μm <R1 or R2 <80 μm

Equation 2

R1-R2 | 〈L <(R1 + R2)

If the value of R1 or R2 is less than 5 μm, the degree of luminance improvement may be insignificant, and if it is larger than 80 μm, it may be disadvantageous in terms of appearance.

When the L value is less than the absolute value of R1-R2, the two hemispheres overlap and the degree of luminance improvement decreases. When the L value is larger than the sum of R1 and R2, the hiding ability may be deteriorated.

As shown in FIGS. 2 to 4, when the single lenticular pattern 201 and the two lenticular patterns have a structured surface in which the lenticular pattern 202 is overlapped, the incident light into the lens pattern is Compared with the case where only a single lenticular pattern is used, the angle of dispersion or scattering becomes wider, thereby improving concealability while widening the viewing angle. In addition, the luminance can be improved by exhibiting a unique light condensing function of the lenticular pattern.

Meanwhile, in the optical film according to the exemplary embodiment of the present invention, the lenticular pattern 201 and / or the lenticular pattern 202 in which the two lenticular patterns are superimposed along the cross section along the vertex axis An inclination angle θ with the base layer formed by drawing an imaginary circle and drawing a tangent line on the adjacent surface of the base layer may satisfy the following expression (3).

Expression 3

90 ° <θ <180 °

If the θ value is less than 90 °, the degree of brightness enhancement may be degraded due to unnecessary light scattering, and may be disadvantageous in terms of viewing angle.

In the optical film according to one embodiment of the present invention, R1 and R2 may be the same or different from each other. In other cases, when the two or more optical films according to the present invention are laminated and used, a pattern such as a ripple pattern is formed on the screen. It is advantageous in that it can prevent the moire phenomenon which is an optical phenomenon which arises, and may be advantageous in brightness improvement in the same case.

Also preferably, in the pattern layer 200 of the present invention, the lenticular pattern 202 in which two lenticular patterns overlap each other is formed at 50 to 95% of the area of the entire pattern layer, thereby improving luminance, supplementing viewing angle, and hiding power. It may be advantageous in terms of reinforcement.

On the other hand, the transparent polymer composition constituting the prism layer is not particularly limited, and conventionally known resins used for a prism sheet or a prism film can be used. For example, the composition may include a mixture of a monomer or oligomer for ultraviolet polymerization and a photoinitiator.

In addition, in the optical film having the optical structure surface of the present invention, the base layer may have a thickness of about 10 to 400 μm, and any base layer may be used as long as it is a sheet made of a transparent resin used for a conventional prism sheet or a prism film. . As an example, a polyethylene terephthalate film, a polycarbonate film, a polypropylene film, a polyethylene film, a polystyrene film, a polyepoxy film, etc. are mentioned.

Although the present invention has been described with reference to the accompanying drawings, the present invention is not limited thereto, and those skilled in the art to which the present invention pertains may change the present invention without departing from the technical spirit of the present invention. Do.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the scope of the present invention is not limited to these Examples.

Comparative Example 1

Using a polyethylene terephthalate film as a base layer, 80 parts by weight of low refractive acrylate, 15 parts by weight of 2-phenylethyl methacrylate, 3 parts by weight of 1,6-hexanediol acrylate, and 2 parts by weight of BAPO-based photoinitiator. An optical film in which a prism layer was formed to have a structured surface having a random microlens array pattern arranged as shown in FIG.

At this time, the diameter of the lens was adjusted so that the number of lenses of the micro lens array is 34 per square 300㎛.

&Lt; Example 1 >

In manufacturing the optical film in the same manner as in Comparative Example 1, as shown in FIGS. 2 to 4, a portion of the pattern layer is formed as a lenticular pattern 202 having two patterns overlapping to form a single lenticular pattern ( 201) and an optical film including a pattern layer having a mixture of lenticular patterns 202 having two patterns overlapped.

In this case, in the lenticular pattern 202 having the two patterns overlapped, R1 and R2 were both 60 μm, and L was 115 μm.

At this time, θ was set to 95 °.

In addition, the lenticular pattern 202 having two lenticular patterns overlapped was set to 50 to 80% of the total pattern layer area.

<Examples 2 to 16>

As shown in Table 1, R1, R2, and L, and two lenticular patterns in the same manner as in Example 1 except that the pattern layer was formed while adjusting the area where the lenticular pattern of the overlapping form is distributed An optical film was produced.

<Comparative Examples 2 to 5>

As shown in Table 1, except that the pattern layer was formed while adjusting R1, R2 and L, an optical film was prepared in the same manner as in Example 1.

R1 (㎛) R2 (㎛) L (μm) θ (°) Area ratio of the lenticular pattern having the form where two lenticular patterns overlap Example 1 60 60 115 95 70 Example 2 60 60 110 105 70 Example 3 60 60 115 105 70 Example 4 60 60 110 95 70 Example 5 30 30 55 95 50 Example 6 30 30 50 105 50 Example 7 30 30 55 105 50 Example 8 30 30 50 95 50 Example 9 40 70 105 95 80 Example 10 40 70 100 105 80 Example 11 40 70 105 105 80 Example 12 40 70 100 95 80 Example 13 20 70 85 95 60 Example 14 20 70 80 105 60 Example 15 20 70 85 105 60 Example 16 20 70 80 95 60 Comparative Example 1 30 30 75 85 0 Comparative Example 2 3 3 10 85 0 Comparative Example 3 20 40 80 75 0 Comparative Example 4 90 90 190 80 0 Comparative Example 5 20 80 120 70 0

For each optical film obtained according to the above Examples and Comparative Examples, the viewing angle, concealability, and luminance were measured, and the results are shown in Table 2 below.

Specific evaluation methods are as follows.

(1) luminance

Luminance was measured using Topcon's BM-7, and the values were removed except for the reflective sheet and diffuser in the backlight unit (BLU, 24 inches). ", And the brightness of each Example and the comparative example was evaluated by the relative value when the brightness of the optical sheet combination containing the comparative example 1 is set to 100."

(2) viewing angle

Viewing angle was measured using Topcon's BM-7, and the value was removed from the back light unit (BLU, 24 inch) except for the reflection sheet and diffuser sheet. Combination, the viewing angle of the position having half the luminance value relative to the front (viewing angle = 0 DEG position) luminance according to each optical sheet combination was measured.

(3) concealability

The concealability was measured using Topcon's BM-7, and the value was removed except for the reflective sheet and diffuser plate in the backlight unit (BLU, 24 inch). By using the step point measurement method in the vertical direction of the BLU according to each optical sheet combination, and measuring the concealability of the optical film by the ratio of the fluctuation value of the luminance to the maximum value of the measured luminance value. Specifically, the equation is as follows.

Concealability (%) = (wave width of luminance) / (maximum measured luminance value) * 100

= (Maximum of Wave of Luminance-Min of Wave of Luminance) / (Maximum measured luminance value) * 100

division Viewing angle (°) Concealable Luminance (%) Example 1 50 28 115 Example 2 51 26 112 Example 3 54 27 110 Example 4 50 29 118 Example 5 51 32 110 Example 6 52 33 108 Example 7 54 31 106 Example 8 50 29 113 Example 9 52 31 107 Example 10 53 32 105 Example 11 51 30 104 Example 12 50 32 109 Example 13 54 29 105 Example 14 51 28 103 Example 15 52 30 102 Example 16 53 27 107 Comparative Example 1 49 35 100 Comparative Example 2 53 38 75 Comparative Example 3 47 42 83 Comparative Example 4 45 56 95 Comparative Example 5 51 48 88

From the results of Table 2, it can be seen that the hiding power, viewing angle and brightness of the optical film provided by the present invention is excellent.

1 is a perspective view of a conventional prism sheet.

2 is a perspective view of a prism sheet according to an embodiment of the present invention.

3 is a cross-sectional view of the prism sheet according to an embodiment of the present invention.

Claims (4)

A patterned layer having a structured surface and composed of a transparent polymer composition; An optical film comprising a base layer adjacent to a flat surface of a pattern layer, The pattern layer has a structured surface in which a plurality of lenticular patterns are formed in succession, and a single lenticular pattern and a lenticular pattern in which two lenticular patterns are superimposed are mixed, and two lenticular patterns overlap. The lenticular pattern in the shape of the shape is drawn by a virtual circle along the cross section of the axial point of each lenticular pattern, and the radius of any one lenticular pattern formed adjacent to the base layer is set to R1, and adjacent to this. It is assumed that the radius of the lenticular pattern is R2, and when L is the line connecting each half diameter point formed adjacent to the base layer, R1, R2 and L satisfy the following equations (1) and (2). An optical film characterized by the above-mentioned. Equation 1 5 μm <R1 or R2 <80 μm Equation 2 R1-R2 | 〈L <(R1 + R2) The lenticular pattern of claim 1, wherein two lenticular patterns overlap each other, and an inclination angle θ with a base layer formed by drawing a virtual circle along a vertex-axis cross section and tangentially adjacent to the base layer is formed. The optical film which satisfy | fills following Formula 3. Expression 3 90 ° <θ <180 ° The optical film of claim 1, wherein R1 and R2 are the same as or different from each other. The optical film according to claim 1, wherein the lenticular pattern in which the two lenticular patterns overlap each other is formed at a ratio of 50 to 95% of the total pattern layer area.

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