KR20100010848A - Optical sheet with reduced defect visibility and filter comprising the same, and image displaying device having the sheet or the filter - Google Patents

Abstract

PURPOSE: An optical sheet with reduced defect visibility and an image display device having a sheet or filter are provided to improve image quality and productivity and increase optical transmission rate and resolution. CONSTITUTION: An optical transmission part(210) comprises plural recesses at image light source or observer end which is separately placed. Plural external light absorbers(220) have a light absorbing material filled at a groove. A depressed part(200a) is opened at one side of partial groove in which external light absorber is not filled.

Description

 Optical sheet with reduced defect visibility and filter comprising the same, and image displaying device having the sheet or the filter

The present invention relates to an optical sheet, a filter including the same, and an image display device including the optical sheet or the filter, and more particularly, poor visibility of white lines and defects is reduced, thereby improving image quality and production yield. The present invention relates to an optical sheet capable of increasing the resolution by improving light transmittance and suppressing a decrease in contrast ratio of an image due to external light, a filter having the same, and an image display device including the optical sheet or the filter.

Recently, many kinds of image display devices have been developed and put into practical use. Such image display devices are, for example, liquid crystal image display devices (LCDs), plasma display panels (PDPs), electroluminescent displays (FEDs), and cathode ray tube image display devices. (CRT), fluorescent display tubes, field emission display panels. Such image display devices display color images by implementing three primary colors of red, blue, and green in principle.

In addition, these image display apparatuses include a panel assembly for forming an image, and a filter for shielding electromagnetic waves, near infrared rays, and / or orange light emitted from the panel assembly, and having a function such as surface reflection prevention and / or color correction. Since these filters are mounted on the front of the panel assembly, the light transmission must also be satisfied at the same time.

However, such a filter has a problem of lowering the brightness of an image display device by absorbing and / or reflecting light emitted from the panel assembly. In addition, in the image display apparatus, in an external bright condition, that is, a bright room condition, external ambient light may pass through a filter into the panel assembly. In this case, superimposition of the image light emitted in the panel assembly and the external environmental light introduced through the filter from the outside occurs, which results in a low contrast ratio under bright room conditions, resulting in poor display capability of the image display device. There is a problem.

In order to solve these problems, a conventional optical sheet generally has a structure in which a wedge-shaped external light absorbing part including a light absorbing material is disposed at a predetermined interval, and the external light absorbing part absorbs external ambient light. By this, the contrast ratio of the image can be improved.

In general, the external light absorbing portion is formed by filling a light absorbing material into each of the plurality of groove portions formed in the light transmitting portion. It is common for such grooves not to be completely filled with the light absorbing material but a part of them to form the depression of the optical sheet. In this case, the filling ratio of the light absorbing material filling the grooves is not usually uniform. For this reason, the depths between the recesses (that is, the portions of the grooves of the light transmitting portion that are not filled with the external light absorbing portions) respectively positioned on two adjacent light absorbing portions among the plurality of external light absorbing portions are frequently different from each other. . Therefore, when an image display apparatus employing such an optical sheet is used, there is a problem in that a white line is recognized from the screen and the viewer perceives that image quality is poor.

An object of the present invention is to provide an optical sheet capable of reducing defect visibility such as white lines and defects, thereby improving image quality and production yield.

Another object of the present invention is to provide an optical sheet capable of improving contrast ratio in bright conditions.

Still another object of the present invention is to provide a filter including the optical sheet.

Still another object of the present invention is to provide an image display apparatus having the optical sheet or the filter, which can reduce defect visibility such as white lines and defects, thereby improving image quality and improving resolution.

The present invention to solve the above problems,

A light transmitting portion having a plurality of groove portions spaced apart from each other and formed at an image light source side or an observer side end portion; And

A plurality of external light absorbing parts filled in the groove part and including a light absorbing material;

At least a portion of the groove portion in which the external light absorbing portion is not filled forms a depression in which one side is opened,

The difference Δd between the maximum depths of each of the two recesses adjacent to each other among the depressions always provides the optical sheet satisfying the following condition.

0.01 µm ≤ | Δd | ≤ 1 μm

According to one embodiment of the invention, the optical sheet, when measured by ASTM D1003, has a haze value (% H) in the range of 5 to 25%.

According to another embodiment of the invention, the width of the external light absorbing portion is in the range of 10 to 40㎛, the maximum depth of the depression is in the range of 0.1 to 20㎛.

According to another embodiment of the invention, the height of the external light absorbing portion is in the range of 50 to 200㎛, the maximum depth of the depression is in the range of 0.1 to 20㎛.

According to another embodiment of the present invention, the shape of the cross section in the thickness direction of the external light absorbing portion is triangular, square or trapezoidal.

According to another embodiment of the present invention, the external light absorbing portion is arranged in a stripe shape, a matrix shape, or a wave shape.

According to another embodiment of the present invention, the optical sheet is a contrast ratio improving sheet.

In addition, the present invention to solve the above problems,

Provided are a filter for an image display device including an optical sheet and a filter base according to any one of the above embodiments.

According to an embodiment of the present invention, the filter base includes an antireflection film, a hard coating layer, an electromagnetic wave shielding film, or a combination thereof.

According to another embodiment of the present invention, the image display device filter further includes a color correction film disposed on the image light source side surface of the optical sheet.

In addition, the present invention to solve the above problems,

An image display device having a filter for an optical sheet or an image display device according to any one of the above embodiments is provided.

According to the present invention, an optical sheet capable of reducing defect visibility such as white lines and defects and improving image quality and production yield can be provided.

In addition, according to the present invention, an optical sheet capable of improving contrast ratio in bright room conditions may be provided.

In addition, according to the present invention, a filter including the optical sheet may be provided.

In addition, according to the present invention, by providing the optical sheet or the filter can be provided an image display device that can reduce the poor visibility of white lines and defects, such that the image quality is improved and the resolution can be improved.

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

1 is an exploded perspective view of an image display apparatus equipped with a filter including an optical sheet according to an embodiment of the present invention, and FIG. 2A is an exploded cross-sectional view of a filter including an optical sheet according to an embodiment of the present invention. 2B is an exploded cross-sectional view of a filter having an optical sheet according to another embodiment of the present invention.

Referring to FIG. 1, an image display device 1 including an optical sheet according to an embodiment of the present invention includes a case 10, a cover 50 covering an upper portion of the case 10, and the case 10. A driving circuit board 20 accommodated therein, a panel assembly 30 for forming an image, and a filter 40.

The visible image formed in the panel assembly 30 by the electrical signal applied from the driving circuit board 20 is emitted to the outside through the filter 40.

This filter 40, as shown in Figures 2a and 2b, includes a color correction film 100, an optical sheet 200, and a filter base (FB), the filter base (FB) is electromagnetic waves It comprises a shielding film 300, hard coating layer 400, and the anti-reflection film (500).

The color correction film 100 typically includes, for example, a neon light blocking dye, but may also include a near infrared absorbing compound or a dye.

The optical sheet 200 includes a base film 230, a light transmitting unit 210, and an external light absorbing unit 220, and is disposed below the color correction film 100. The optical sheet 200 having such a configuration includes, for example, a contrast ratio improving sheet, but the present invention is not limited thereto. Here, the contrast ratio improvement sheet is a broad concept which collectively refers to the sheet used for the purpose of raising the contrast ratio of an image display apparatus.

The light transmitting portion 210 is a portion that transmits the light emitted from the panel assembly 30 of FIG. 1. The light transmitting part 210 may be formed of a curable resin. Specifically, the light transmitting portion 210 may be used an acrylate resin or the like cured by ionizing radiation or thermal energy.

In addition, the light transmitting unit 210 is preferably transparent, which means not only completely transparent but also to the extent that it can be recognized as transparent in the art. The light transmitting part 210 generally has a shape complementary to the shape of the external light absorbing part 220 to be described later, but the present invention is not limited thereto. That is, the light transmitting portion 210 is formed with groove portions g ₂₁₀ spaced apart from each other at predetermined intervals, and the groove portion g ₂₁₀ is filled with a light absorbing material to form an external light absorbing portion 220 which will be described later. do. This groove (g ₂₁₀₎ and the external light absorption unit 220 may be formed on one end, that is the image light source-side end of the light transmission portion 210 and (see Figure 2a, Figure 2b, and Figure 3), a viewer-side end It may be formed (not shown). It is preferable that the refractive index of the light transmitting unit 210 is 1.3 to 1.8. If the refractive index is less than 1.3, it is not preferable because it is difficult to manufacture, and if it exceeds 1.8, the transmittance of the light transmitting unit 210 is significantly decreased and the contrast ratio is also reduced, which is not preferable because the overall resolution is reduced. In the present embodiment, the optical sheet 200 is manufactured in a state in which a part of the groove g ₂₁₀ is empty without a light absorbing material being completely filled in the groove g ₂₁₀ of the light transmitting part 210. Hereinafter, the unfilled space of the groove part g ₂₁₀ will be referred to as the recessed part 200a of the optical sheet 200. However, the present invention is not limited thereto. For example, the recess 200a may be formed by pressing and compressing the elastic wiping blade when the groove g ₂₁₀ is filled with the light absorbing material, g ₂₁₀ ) may be formed by completely filling the light absorbing material, and then additionally compressing the filled light absorbing material by wiping or the like, and may be formed by curing or drying the external light absorbing part with a shrinkable resin. It may be. Specifically, the recessed portion 200a is formed in at least a portion of the groove portion g ₂₁₀ , as shown in FIGS. 2A and 2B, and is defined by the light transmitting portion 210 and the external light absorbing portion 220. One side is open. By forming the recess 200a as described above, the optical sheet 200 may improve the light transmittance while suppressing the decrease in the external light absorption rate, which will be described later.

In the present invention, the difference Δd between the maximum depths of each of the two recesses adjacent to each other among the plurality of recesses 200a always satisfies the following condition.

0.01 µm ≤ | Δd | ≤ 1 μm

Δd is d _{a + 1} -d _a , d _a -d _a-1 , or d _a-1 -d _a-2 .

When Δd is less than 0.01 μm, there is an advantage that the depth difference between the recesses 200a decreases, so that the optical sheet 200 has a uniform appearance. 200) There is a problem that a process defect due to its own defect or mixing of foreign matters is easily observed. On the other hand, when Δd exceeds 1 μm, the corresponding depression 200a is recognized as a white line. For example, d _a -d _a-1 and d _a-1 -d _a-2 are less than or equal to 1 μm, and d _{a + 1} -d _a is greater than 1 μm, corresponding to d _{a + 1} The depression 200a of the position is recognized as a white line. Here, "white line" means that white lines or dots or the like are observed on a specific portion of the optical sheet (for example, a depression in the form of a stripe). By adjusting Δd in this manner, both the bad visibility and the white line visibility are reduced, and on the one hand, as the defective rate is reduced, the production yield can be increased and on the other hand, the image quality can be improved.

As described above, the external light absorbing part 220 is formed by filling a thermoplastic resin, a thermosetting resin or an ultraviolet curable resin, and a light absorbing material in the groove part g ₂₁₀ formed in the light transmitting part 210, thereby absorbing external ambient light. It is to maintain the high resolution by improving the contrast ratio in the bright room condition. 2A illustrates a case in which one end face of the external light absorbing unit 220 has a quadrangle shape, and FIG. 2B illustrates a case in which one end face of the external light absorbing unit 220 has a trapezoidal shape.

When the curable resin is used when forming the external light absorbing part 220, the same or similar material as that of the light transmitting part 210 may be used as the curable resin.

The light absorbing material may include, for example, a black inorganic material, a black organic material, a blackened metal, and a mixture of two or more thereof. In the case of blackened metal, since the electrical resistance is low, when it is included in the external light absorbing unit 220, the electrical resistance can be controlled by adjusting the content of the metal powder or the thickness of the metal thin film, so that the external light absorbing unit 220 shields electromagnetic waves. You can also perform a function. Typically, the external light absorbing unit 220 may be formed of an ultraviolet curable resin containing carbon. The refractive index of the external light absorbing unit 220 is preferably in the range of 1.3 to 1.8, similar to the light transmitting unit 210.

 The base film 230 is disposed on one surface of the light transmitting portion 210, that is, on the surface opposite to the recessed portion 200a. The base film 230 serves to support the light transmission unit 210 in which the external light absorbing unit 220 is disposed. Specifically, the base film 230 is polyethersulphone (PES), polyacrylate (PAR, polyacrylate), polyether imide (PEI, polyetherimide), polyethylene naphthalate (PEN, polyethyelene naphthalate), polyethylene terephthalate (PET, polyethyleneterephthalate), polyphenylene sulfide (PPS), polyallylate, polyimide, polycarbonate (PC), cellulose tri acetate (TAC), cellulose acetate propionate (cellulose acetate propionate (CAP)) may be formed of one or more substances selected from the group consisting of: Preferably, it may be polycarbonate (PC), polyethylene terephthalate (PET, polyethyeleneterephthalate), cellulose tri acetate (TAC), or polyethylene naphthalate (PEN, polyethyelene naphthalate). In addition, the base film 230 may be formed of a material having a refractive index that is the same as or similar to that of the light transmitting unit 210.

In addition, the optical sheet 200 according to the present embodiment further includes a protective film 240 on one surface of the light transmitting unit 210, that is, the surface opposite to the base film 230, as shown in FIG. 3 to be described later. can do. The protective film 240 serves to protect the optical sheet 200 until the optical sheet 200 is mounted on the filter 40, which is separated from the optical sheet 200 when the filter 40 is assembled. It is common. However, the present invention is not limited thereto.

On the other hand, the depression 200a is preferably filled with the pressure-sensitive adhesive layer and / or color correction film 100 when the filter 40 is assembled, but the present invention is not limited thereto. When the recess 200a is filled with the pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer is preferably formed of a material having the same or similar refractive index as that of the light transmitting part 210.

The optical sheet having the above configuration, when measured by ASTM D1003, has a haze value (% H) in the range of 5 to 25%.

2A and 2B, the filter base FB is disposed on one surface of the optical sheet 200 and includes an electromagnetic wave shielding film 300, a hard coating layer 400, and an antireflection film 500. It is not limited. The stacking order of these 300, 400, and 500 in the filter base FB may be variously changed, and a material having two or more functions may be mixed in one layer to form a layer.

The electromagnetic wave shielding film 300 is responsible for shielding electromagnetic waves. The electromagnetic wave shielding film 300 may have various configurations such as a conductive mesh layer, a metal thin film, a high refractive index transparent thin film, or a structure in which two or more of them are stacked. 2A and 2B, the electromagnetic shielding film 300 is illustrated as being composed of a single layer. However, the present invention is not limited thereto, and may be formed of a multilayer including at least two layers.

The hard coating layer 400 has scratch resistance to prevent the electromagnetic wave shielding film 300 or the anti-reflection film 500 described later from being damaged due to contact with an external material. The hard coating layer 400 may be tempered glass itself, or may be a material including a polymer as a binder. In addition, the hard coating layer 400 may include an acrylic, urethane, epoxy, or siloxane polymer, or may include an ultraviolet curable resin such as an oligomer. In addition, a silica-based filler may be added to the hard coat layer 400 to improve the hardness.

The anti-reflection film 500 is responsible for minimizing eye fatigue of image display device users who watch for a long time by adjusting the transmittance of visible light. By arranging the antireflection film 500 in this way to adjust the visible light transmittance, in addition to the selective absorption effect of the visible light, it is possible to obtain an effect of improving the color reproduction range such as contrast ratio. 2A and 2B, the anti-reflection film 500 is illustrated as being composed of a single layer. However, the present invention is not limited thereto, and may be formed of a multilayer including at least two layers.

The anti-reflection film 500 has a visible light incident from the outside and reflected from the surface of the anti-reflection film 500, and then the visible light reflected from the interface between the anti-reflection film 500 and the hard coating layer 400 is reversed. The antireflection effect is obtained by the principle of phase disappearance and interference phenomenon.

As the anti-reflection film 500, a mixture of indium tin oxide (ITO) and silicon oxide (SiO ₃ ), a mixture of nickel chromate (NiCr) and silicon oxide (SiO ₂ ), and the like may be cured and adhered. In addition, a special fluorine resin of titanium oxide or low refractive index may be used as the antireflection film 500.

Hereinafter, specific configurations and effects of the light transmitting unit 210, the external light absorbing unit 220, and the recess 200a will be described in detail with reference to the accompanying drawings.

3 is an enlarged cross-sectional view of the optical sheet of FIG. 2A and illustrates a state before the optical sheet is mounted on the filter, and FIG. 4 is an enlarged view of portion A of FIG. Note that in Figures 3 and 4 the protective film was not removed.

The same reference numerals as in the above-described drawings indicate the same member or parts of the same member.

The external light absorbing part 220 may include a thermoplastic or thermosetting resin in a roll molding method, a heat press method using a thermoplastic resin, or a light transmitting part 210 to which a groove g ₂₁₀ having a shape opposite to the pattern of the external light absorbing part 220 is transferred. It may be formed by an injection molding method of filling and molding. In addition, when the ultraviolet curable resin constituting the light transmitting unit 210 has an antireflection function, an electromagnetic shielding function, a color correction function, or a combination thereof, the optical sheet 200 may additionally perform these functions. have.

3 and 4, the optical sheet 200 according to the present embodiment includes a light transmitting unit 210, an external light absorbing unit 220, a base film 230, and a protective film 240. Here, the protective film 240 may be omitted by selection. FIG. 2A is a diagram illustrating a filter 40 equipped with the optical sheet 200 from which the protective film 240 is removed.

The relative arrangement of the light transmitting unit 210, the external light absorbing unit 220, the base film 230, and the protective film 240 is as described above.

The external light absorbing part 220 may be arranged in various shapes such as a stripe shape, a matrix shape, or a wave shape. In addition, the plurality of external light absorbing units 220 may be spaced apart from each other to allow light to pass therebetween. In addition, in FIG. 3, the external light absorbing unit 220 is illustrated as one end surface of a rectangular shape, but the present invention is not limited thereto. The shape of the one end surface may be various shapes such as triangle, trapezoid, or pentagon.

As described above with reference to FIGS. 2A and 2B, the external light absorbing part 220 and the recessed part 200a are sequentially formed in the groove part g ₂₁₀ of the light transmitting part 210. That is, most of the groove g ₂₁₀ is filled with the light absorbing material to form the external light absorbing part 220, and the remaining part not filled with the light absorbing material constitutes the depression 200a. Although the recessed part 200a is formed in the shape of one end in the width direction in the shape of U, the present invention is not limited thereto. When the optical sheet is combined with the color correction film 100 or the like to form the filter 40, the recess 200a is filled with an adhesive layer (not shown) having a refractive index equal to or similar to that of the light transmitting unit 210.

In the present invention, the maximum depth of the depression 200a (d _{a +1} , d _a , d _a-1 , d _a-2 are important, which means that the depth (d _{a + 1} , d _a , d _a-1 , d _a-2 ) have more influence on the white line formation than the depth of the other parts. Specifically, when the difference Δd between the maximum depths of two neighboring depressions is within a range of 0.01 μm to 1 μm, both defect and white line visibility may be reduced.

In the present invention, the maximum depth d _imax of the interface between the depression 200a and the light transmitting portion 210 is also important, which is the depth of the portion where the depth d _imax is different (for example, d _a-1 This is because the light transmittance affects more than). To exemplarily illustrate this, a case in which the light L ₁ and the light L ₂ are incident to the optical sheet 200 from the image light source side will be described with reference to FIG. 4. Herein, when the light L ₁ is assumed that the recess 200a is not formed, the rightmost light of the image light source that may be transmitted to the light transmitting part 210 positioned on the left side of the external light absorbing part 220 on the accompanying drawings. When the depression 200a is formed as in the present invention, the light L ₂ is the rightmost side of the image light source that can be transmitted to the light transmission unit 210 positioned on the left side of the external light absorbing unit 220 in the drawing. Means light. In this case, when the depression 200a is formed, the light between the light L ₁ and the light L ₂ is further transmitted through the light transmitting portion 210 as compared with the case where the depression 200a is not formed. This, in turn, increases the light transmittance of the optical sheet 200 and increases the luminance of the image display device employing the optical sheet 200.

Optical sheet 200 of the present invention, by forming a groove (g ₂₁₀₎ in the light transmission portion 210, as described above, and filling a light-absorbing material only some of the groove (g _210), the external light absorption unit 220 Since the filling process of the light-absorbing material is made easier, not only the manufacturing cost is reduced compared to the prior art, but also the light-absorbing material remains on the light transmitting part 210 around the groove part g ₂₁₀ during filling. The problems of the prior art can also be improved.

In addition, the maximum depth (d _{a +1} ,) of the depression 200a, d _a , d _a-1 , and d _a-2 have a value in the range of 0.1 to 20 μm when the width W ₂₂₀ of the external light absorbing unit 220 is in the range of 10 to 40 μm.

Here, the width W _{220 of the} external light absorbing unit 220 refers to the width of the end portion of the image light source in the present embodiment, and when the shape of the external light absorbing unit 220 is trapezoidal as shown in FIG. 2B. The width W ₂₂₀ refers to the width of the end portion of the image light source side of the external light absorbing part 220, that is, the maximum width.

In addition, the maximum depth (d _{a +1} ,) of the depression 200a, d _a , d _a-1 , and d _a-2 have a value in the range of 0.1 to 20 μm when the height h ₂₂₀ of the external light absorbing unit 220 is in the range of 50 to 200 μm.

Although not shown here, the optical sheet 200 according to the present embodiment may further include a prism portion disposed on one surface of the base film 230, that is, the surface opposite to the light transmitting portion 210. The prism portion may be formed of the same or similar material as that of the light transmitting portion 210. By providing the prism portion as described above, the optical sheet 200 has improved external light absorption without large change in transmittance, thereby increasing the contrast ratio and improving the resolution.

An optical sheet or a filter having the above-described configuration may be provided in the image display apparatus, thereby reducing defect visibility such as white lines and defects of the image display apparatus, thereby improving image quality and increasing contrast ratio. Can be achieved.

Hereinafter, the present invention will be described in more detail with reference to preferred embodiments, but the present invention is not limited thereto.

Example 1

A molding roll was formed in which a plurality of protrusions having a square cross-sectional shape were formed on the surface. Then, a low refractive index acrylic curing resin mixture liquid (Sartomer) on one surface between the optical PET film (Toyobo) having a thickness of 188㎛ constituting the forming roll and the base film 230 by using a pattern roll equipment equipped with an ultraviolet device. , CN-981) 100g (refractive index: 1.48) was added slowly to cure. This obtained the light transmission part 210 of refractive index 1.48 by which the protrusion part on the said molding roll was transferred in the groove shape. In the transferred groove shape, a carbon dispersion (refractive index: 1.49) prepared by mixing 2 g of carbon black with 100 g of acrylic curing resin (Sartomer, CN-985) and scattering a Dr. blade made of soft plastic A plurality of external light absorbing parts 220 having a refractive index of 1.49 were formed by wiping the wafers to evenly fill the grooves to form a plurality of depressions having an average maximum depth of 3 μm in the grooves. In this case, by performing wiping while oscillating the soft doctor blade at 3 to 20 rpm, the difference Δd between any two neighboring depressions among the formed depressions is always 0.01 to 1 μm. Adjusted to fall within the range. Thereafter, curing was performed with ultraviolet rays to obtain an optical sheet 200 having depressions as shown in FIG. 3. Here, the pitch of the light transmitting portion 210 was 74㎛, the height and width of the external light absorbing portion 220 were 102㎛ and 24㎛, respectively, and the thickness of the light transmitting portion 210 was 150㎛. Here, the pitch of the light transmitting portion 210 means the distance between the points corresponding to each other in the light transmitting portion 210 of the two adjacent portions partitioned by the external light absorbing portion 220.

Comparative Example 1

By repeating the wiping operation with the doctor blade three times, in any two neighboring depressions among the plurality of depressions, the difference Δd between their respective maximum depths is always adjusted to be smaller than 0.01 μm. Except that, an optical sheet was manufactured in the same manner as in Example 1.

Comparative Example 2

By maintaining the vibration speed of the doctor blade to less than 3 rpm during the wiping operation using the doctor blade, the difference (Δd) between their respective maximum depths in any two neighboring depressions among the plurality of depressions is 1 ~. An optical sheet was manufactured in the same manner as in Example 1, except that it was adjusted to fall in the range of 3 μm.

Evaluation example

As a result of evaluating the prepared optical sheet, white line and defect occurrence by visual observation, and haze value (% H) measured by ASTM D1003 are shown in Table 1 below. (Circle) when white line or defect was observed visually, and (x) when it was not observed visually.

TABLE 1

Analysis item Example 1 Comparative Example 1 Comparative Example 2 White line × × ○ Bad × ○ × Haze value (% H) 13 3 32

Referring to Table 1, in the case of Example 1 belonging to the present invention, neither white lines nor defects were observed, whereas in Comparative Example 1, the depth of the depressions was uniformly formed so that white lines were not observed but defects, etc. Defects were clearly observed. In addition, in the case of Comparative Example 2, no defect was observed, but the white line was clearly observed in a large amount due to the rapid change in the depth of the depression. In addition, it can be seen from the results of Table 1 that there is an appropriate range of haze values (% H) in which both whiteline visibility and poor visibility are reduced.

In the above described a preferred embodiment according to the present invention with reference to the drawings, but this is only exemplary, those skilled in the art can understand that various modifications and equivalent other embodiments are possible from this. There will be. Therefore, the protection scope of the present invention should be defined by the appended claims.

1 is an exploded perspective view showing a schematic configuration of an image display device equipped with a filter including an optical sheet according to an embodiment of the present invention.

2A is an exploded cross-sectional view of a filter having an optical sheet according to an embodiment of the present invention, and FIG. 2B is an exploded cross-sectional view of a filter having an optical sheet according to another embodiment of the present invention.

3 is an enlarged cross-sectional view of the optical sheet of FIG. 2A and illustrates a state before the optical sheet is mounted on the filter.

4 is an enlarged view illustrating a portion A of FIG. 3.

<Explanation of symbols for the main parts of the drawings>

1: image display device 10: case

20: drive circuit board 30: panel assembly

40: filter 50: cover

100: color correction film 200: optical sheet

200a: depression 210: light transmission unit

220: outside light absorbing portion d: depth of the depression

230: base film 240: protective film

300: electromagnetic wave shielding film 400: hard coating layer

500: antireflection film FB: filter base

g ₂₁₀ : groove

Claims (9)

A light transmitting portion having a plurality of groove portions disposed to be spaced apart from each other and formed at an image light source side or an observer side end portion; And A plurality of external light absorbing parts filled in the groove part and including a light absorbing material; At least a portion of the groove portion in which the external light absorbing portion is not filled forms a depression in which one side is opened, The difference (Δd) between the maximum depths of each of the two recesses adjacent to each other among the depressions always satisfies the following condition. 0.01 µm ≤ | Δd | ≤ 1 μm The method of claim 1, Optical sheet, characterized by haze value (% H) in the range of 5-25%, as measured by ASTM D1003. The method of claim 1, The width of the external light absorbing portion is in the range of 10 to 40㎛, the maximum depth of the depression is an optical sheet, characterized in that in the range of 0.1 to 20㎛. The method of claim 1, The height of the external light absorbing portion is in the range of 50 to 200㎛, the maximum depth of the depression is an optical sheet, characterized in that in the range of 0.1 to 20㎛. The method of claim 1, Optical sheet, characterized in that the shape of the cross section in the thickness direction of the external light absorbing portion is triangular, square or trapezoidal. The method of claim 1, And the external light absorbing portion is arranged in a stripe shape, a matrix shape, or a wave shape. The method of claim 1, And the optical sheet is a contrast ratio improving sheet. A filter for an image display device, comprising the optical sheet according to any one of claims 1 to 7, and a filter base. An image display device comprising the optical sheet according to any one of claims 1 to 7.

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