JPWO2009069304A1 - Lens sheet composite - Google Patents

Abstract

A lens sheet composite comprising a diffuser plate 3 and a lens sheet 2 bonded together by minute adhesive portions 4a distributed over the entire surface, wherein the lens sheet 2 includes diffusing particles 5. 1 is provided. The lens sheet composite of the present invention does not bend or distort even when the thermal expansion coefficients are different, and uniform optical performance can be obtained. It is suitable for a backlight for a liquid crystal display device in which it is difficult to see.

Description

  The present invention relates to a lens sheet composite comprising a lens sheet disposed on the surface side of a backlight of a liquid crystal display device or the like and a diffusion plate, and in particular, handling and assembly workability are good, and the lens structure of the lens sheet is broken. The present invention relates to a lens sheet composite in which uniform optical performance can be obtained even when the thermal expansion coefficient of the diffuser plate and the lens sheet is different, and further, the difference in brightness between the linear light source and the gap between them is difficult to visually recognize. .

  In recent years, liquid crystal display devices have been used in various fields, and various performances are required depending on the respective applications. For office automation equipment, personal computers, word processors, etc., there are strong demands for weight reduction, thinning, high definition, and power saving. Furthermore, for liquid crystal display devices, a wider field of view, wider screen, and higher brightness are required. The demand is getting stronger.

In order to meet these requirements, the directivity of light is changed, that is, a film or sheet (hereinafter simply referred to as a lens) having a condensing function in order to change the direction of light in an unnecessary direction and condense it in front of the observer. The use of sheet) is common.
When this lens sheet is attached to the diffusion plate using an adhesive, the difference in refractive index between the diffusion plate and the adhesive layer or between the adhesive layer and the lens sheet is small, so that the diffusion sheet or the like is changed from the diffusion plate to the lens sheet. Since the emitted light is not collected effectively, the front brightness may hardly increase, and if the lens sheet and the diffusion plate have different coefficients of thermal expansion, they will be bent and distorted, resulting in uniform optical performance. Since there was a problem that it could not be obtained, the assembly was completed simply by superimposing without using an adhesive or the like.
However, in this case, the lens sheet, the diffusion plate, and other members must be handled at the same time so that they are not scattered during assembly, that is, handling and assembly workability are poor, and the cost for assembling the device is low. It was the cause of up.

  In addition, the lens sheet may sway during assembly or when the finished product after assembly is transported simply by overlapping, in this case, the lens surface is rubbed with another optical sheet at this time, The lens structure may be broken and the predetermined optical performance may not be exhibited, or the broken lens structure may become powdery and adhere to other optical sheets to hinder the performance. In order to avoid such a situation, PET having a relatively high strength is often used as a material. However, the degree of freedom in designing the lens sheet is impaired by that amount, and in designing a high-performance lens sheet. It was an obstacle.

Furthermore, in recent years, point light sources such as LEDs have also been used, but a linear cathode ray tube is frequently used, and in order to homogenize the light from the linear light source, it passes through a diffusion plate having a light diffusion function. A planar light source is used. If light is diffused and homogenized to such an extent that the location where the light source is present cannot be visually recognized, the amount of transmitted light is impaired and the light utilization efficiency is deteriorated.
Therefore, in order to increase the light use efficiency and prevent the presence of the light source from being visible, a diffusion sheet with an adjusted light diffusivity is used in the upper or lower part of the lens sheet or both above and below (for example, , See Patent Document 1).
However, in this case, the number of parts increases, and handling properties and assembly workability deteriorate.
JP 2007-3908 A (FIGS. 10 and 13)

  The present invention solves the above-mentioned conventional problems, has good handleability and assembling workability, does not break the lens structure, and can obtain uniform optical performance even when the thermal expansion coefficient is different between optical sheets. It is an object of the present invention to obtain a lens sheet composite in which the existence location of is difficult to visually recognize.

  The present invention has been made in order to achieve the above object, and is a lens sheet composite in which a diffusion plate and a lens sheet are bonded together with minute adhesion portions distributed over the entire surface, wherein the lens sheet contains diffusion particles. The content of the lens sheet composite is characterized by comprising.

  In the invention according to claim 2 of the present invention, the lens sheet has a thickness obtained by removing the lens structure from the lens sheet, and a haze measured by JIS K7136 on a sheet having flat surfaces is 18.0 to 78.0%. The lens sheet composite according to claim 1, comprising:

  The invention according to claim 3 of the present invention is the lens sheet composite according to claim 1 or 2, wherein the diffuser plate has a haze of 11.0 to 95.1% measured according to JIS K7136. The body is the content.

  In the invention according to claim 4 of the present invention, the ratio (B) / (A) of the haze (B) of the lens sheet to the haze (A) of the diffusion plate is from 0.19 to 2.22, and the haze (A) The haze (B) value is 380 or more, and the lens sheet composite according to claim 3 is contained.

  The invention according to claim 5 of the present invention is characterized in that the shape of the adhesive applied to the back surface of the lens sheet is a convex lens shape or a spherical shape. The content is a complex.

The invention according to claim 6 of the present invention is characterized in that the difference in linear expansion coefficient between the diffusion plate and the lens sheet is 5.9 × 10 ⁻⁵ / ° C. or less. The content is the lens sheet composite according to Item 1.

  The invention according to claim 7 of the present invention includes the lens sheet composite according to claim 6, wherein the material of the diffusion plate and the lens sheet is the same.

In the lens sheet composite of the present invention, a diffusion sheet and a lens sheet containing diffusion particles (hereinafter sometimes simply referred to as a lens sheet) are bonded together with minute adhesive portions distributed over the entire surface. Since the lens sheet can be handled integrally, the handling and assembling workability are excellent, and since the lens sheet is fixed to the diffusion plate and does not swing, the lens sheet is formed using a material with low hardness, for example. However, the lens structure is not broken by friction with other optical sheets, and therefore, a lens sheet with high optical performance can be used even if the strength is slightly weak. In addition, since the bonding is partially performed at a fine adhesion portion, and the diffusion particles are included in the lens sheet, the adhesion portion is hidden by the diffusion particles and is hardly noticeable. Even if the thermal expansion coefficient of the diffuser plate and the lens sheet are different, the difference in linear expansion coefficient is absorbed by the partial adhesive part, and the occurrence of bending and distortion is prevented. Optical performance not inferior to the case can be exhibited.
Furthermore, it is possible to provide a high-quality backlight with high brightness of the front surface, in which the difference in brightness between the linear light source and the gap, that is, the location where the linear light source exists is difficult to visually recognize.

When the diffusing particles are blended so that the haze of the lens sheet is 18.0 to 78.0%, coupled with the light diffusing effect of the diffusing plate, the linear light source and the gap between the linear light source and the gap between them are not affected. It is possible to make it difficult to visually recognize the difference in brightness.
Since the lens sheet bends light incident parallel to its normal to a predetermined angle, the haze cannot be measured directly by the method defined in JIS K7136. Thus, the haze is measured for a sheet having a thickness excluding the lens structure from the lens sheet and flat on both sides.

When the diffusing particles are blended in the diffusing plate so that the haze is 11.0 to 95.1%, the diffusing plate functions in the same manner as a normal diffusing plate, and the brightness difference of the backlight is reduced.
In particular, when the haze ratio of the diffuser plate to the lens sheet is 1: 1.19 to 2.22, coupled with the light diffusion effect of the lens sheet, the difference in brightness of the backlight is sufficiently eliminated, and the position of the light source It is possible to maintain the brightness of the entire screen without blocking unnecessary light.

If the difference in linear expansion coefficient between the diffusion plate and the lens sheet is 5.9 × 10 ⁻⁵ / ° C. or less, even if the diffusion plate and the lens sheet expand and contract due to temperature change, the difference in linear expansion coefficient is absorbed by the adhesive part. Therefore, almost no bending or distortion occurs. In particular, since the linear expansion coefficient is the same when the material of the diffusion plate and the lens sheet is the same, no bending or distortion due to a temperature change occurs.

FIG. 1 is a conceptual diagram showing an example of a lens sheet composite of the present invention. FIG. 2 is a conceptual diagram showing another example of the lens sheet composite of the present invention. FIG. 3 is a conceptual diagram showing still another example of the lens sheet composite of the present invention. FIG. 4 is a conceptual diagram of the adhesive surface of the lens sheet used in Example 1. FIG. 5 is a conceptual diagram of the adhesive surface of the lens sheet used in Example 3. FIG. 6 is a conceptual diagram of the adhesive surface of the lens sheet used in Example 4. FIG. 7 is a conceptual diagram of the adhesive surface of the lens sheet used in Example 7. FIG. 8 is a conceptual cross-sectional view showing an example of a protrusion in the present invention. FIG. 9 is a conceptual cross-sectional view showing another example of the protrusion in the present invention. FIG. 10 is a conceptual cross-sectional view showing still another example of the protrusion in the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lens sheet complex 2 Lens sheet 3 Diffusion plate 4 Adhesive 4a Adhesive part 5 Diffusing particle 6 Protrusion

  As shown in FIG. 1, the lens sheet composite 1 of the present invention is formed by bonding the diffusion plate 3 and the lens sheet 2 with the minute adhesive portions 4a of the adhesive 4 distributed over the entire surface. The lens sheet composite 1 is characterized in that the lens sheet 2 includes diffusion particles 5.

The lens sheet 2 used in the present invention has a lens surface provided with a three-dimensional pattern (hereinafter referred to as a lens pattern) having a condensing function on one surface and an adhesive surface on the other surface.
The lens pattern provided on the lens surface is not particularly limited as long as it has a condensing function. For example, usable lens patterns include a large number of triangular prisms having a triangular cross section and adjacent bases, and the top ridges are substantially parallel. Prism arranged in such a way; convex lenticular lens in which a plurality of semi-cylindrical or semi-elliptical cylinders having a semi-circular or semi-elliptical cross section and adjacent bases are arranged substantially parallel to each other; pyramid type quadrangular pyramid Examples thereof include a pattern in which a three-dimensional shape selected from a cubic corner-like triangular pyramid and a hemispherical object is provided on a plane.
Note that a large liquid crystal display device needs to be visible from the left and right sides of the screen, such as when viewing a single screen with a large number of people, but rarely observes the screen from above and below. Therefore, in this type of lens sheet composite 1, it is preferable that the light emitted from the screen is diffused in the left-right direction and condensed in the up-down direction. When a prism lens sheet or a lenticular lens sheet that focuses light only in the direction is used and the lens sheet composite 1 using the lens sheet 2 is installed on the screen, the length direction of the prism or lenticular lens is set with respect to the screen. It is preferable to adjust it horizontally.

  The shape of the adhesive surface is not particularly limited as long as it does not excessively interfere with the light condensing function of the lens surface, but a flat surface without unevenness, an uneven surface with many cylindrical protrusions protruding, and many linear protrusions with a rectangular cross section The provided uneven surface can be exemplified, and a three-dimensional pattern similar to the lens pattern can be provided as long as the condensing function of the lens surface is not canceled.

  The thickness of the lens sheet 2 is not particularly limited, and can be the same thickness as that of a normal lens sheet. Specifically, the thickness is usually about 50 to 500 μm.

In the present invention, the lens sheet 2 includes diffusing particles 5. As the usable diffusing particles 5, all the diffusing particles 5 conventionally used for diffusing plates, diffusing sheets and the like can be used, but it is preferable to select a type having a high total light transmittance and a large haze.
Specifically, examples of the inorganic particles include aluminum silicate, calcium silicate, silica, alumina, calcium carbonate, and the like. Examples of the organic particles include cross-linked polyacrylate and silicon resin.
The average particle diameter of the diffusion particles 5 is preferably 0.5 μm to 25 μm. Even if the average particle size is less than 0.5 μm or more than 25 μm, the diffusion function tends to be lowered.

The diffusion particles 5 have a haze of the lens sheet 2 of preferably 18.0 to 78.0%, more preferably 20.0 to 60.0%, still more preferably 30.0 to 40.0%. The amount is blended into the transparent resin. If the haze is less than 18.0%, a slight dark portion generated in the bonded portion 4a may be seen, and if it exceeds 78.0%, the front luminance may be lowered and the screen may become dark.
Since the specific amount of the diffusing particles 5 varies depending on the transparency, the particle size, the refractive index, the refractive index of the transparent resin constituting the lens sheet 2, the thickness of the lens sheet 2, and the like. For example, when silica particles having an average particle size of 0.5 μm are used as the diffusing particles 5, the transparent resin constituting the lens sheet 2 is polycarbonate, and the thickness of the lens sheet 2 is 120 μm, the amount is 0.1 to 100 g of the transparent resin. About 5 to 1.5 g is blended.

  Usually, the haze is measured by a method defined in JIS K7136. However, since the lens sheet 2 bends light incident in parallel with the normal to a predetermined angle, the haze can be directly measured by this method. Can not. Therefore, in the present invention, using the same material as the lens sheet 2, a sheet having a thickness obtained by removing the lens structure from the lens sheet 2 and flat on both sides is prepared, and the haze of this sheet is set according to JIS K7136. The value was determined as the haze of the lens sheet 2. Thereby, even if the adhesion part 4a is arrange | positioned in the thinnest part (part corresponded to the bottom part of a lens pattern) of the lens sheet 2, the dark part which generate | occur | produces in the adhesion part 4a can fully be hidden.

  The lens sheet 2 can be prepared by a normal method. That is, the diffusion particles 5 are dispersed in the transparent resin in the same manner as in the case of preparing a normal diffusion sheet obtained by blending the diffusion particles 5 with a transparent resin, and a normal lens sheet is prepared using this resin. A lens sheet used in the present invention by a method similar to the above, for example, a method in which a resin is extruded between a metal roll and a rubber roll on which a lens pattern is engraved, and the lens pattern is transferred between the metal roll and the rubber roll. Can be created.

The diffusion plate 3 used in the present invention has a light incident surface on which light from a backlight is irradiated and an adhesive surface to which the lens sheet 2 is adhered.
The diffusing plate 3 in the present invention may be a translucent translucent plate-like member that does not warp or bend due to its own weight, and examples thereof include an acrylic or polycarbonate plate in which the diffusing particles 5 are dispersed and blended. However, in the present invention, since the lens sheet 2 has a part of the dispersing action, the amount of the diffusing particles 5 can be smaller than that of a normally used diffusing plate, and the total amount of light is increased by that amount. Brightness also increases.

  If the haze of the diffusion plate 3 is extremely low and only the lens sheet 2 has a diffusing action for eliminating the difference in brightness due to the backlight being seen through, the translucency of the lens sheet 2 is significantly reduced. On the other hand, the transmissivity of the entire lens sheet composite 1 is lowered and the front luminance tends to be lowered, so that the haze of the diffusion plate 3 is 11.0 to 95.1%, and more preferably 30.0 to 90. It is preferable to mix the diffusing particles 5 so as to be 0%, particularly 50.0 to 85.0%, and lower the haze of the lens sheet 2 by that amount to be within the above range. When the haze of the diffusing plate 3 exceeds 95.1%, the haze of the diffusing plate is sufficient to eliminate the difference in brightness of the backlight alone, and the lens sheet 2 is sufficient to eliminate the dark portion generated alone in the bonding portion 4a. Since the hazes of the lens sheets overlap, the transmissivity of the entire lens sheet composite 1 tends to decrease and the front luminance tends to decrease.

  The ratio (B) / (A) of the haze (B) of the lens sheet 2 to the haze (A) of the diffusion plate 3 is preferably 0.19 to 2.22, more preferably 0.20 to 0.81, and still more preferably. Is adjusted to 0.40 to 0.50, and the haze (A) × haze (B) value is preferably 380 or more, more preferably 850 or more, the lens sheet composite 1 As a whole, the difference in brightness of the backlight can be effectively eliminated, the dark part generated in the adhesive part 4a can be hidden by the lens sheet 2, and the light transmittance is not lowered so much to increase the front luminance. Can do. The upper limit of the value of haze (A) x haze (B) is preferably about 7000 from the viewpoint of making it difficult to visually recognize the difference in brightness and ensuring light transmittance.

  In the present invention, the lens sheet 2 and the diffusing plate 3 are bonded to each other at a minute bonding portion 4a. The specific bonding method is not particularly limited as long as the area of each bonding portion 4a is small. For example, as shown in FIG. 1, a so-called spray that sprays a fine spherical bonding component with a spray. A method of using glue, a method of using a so-called curtain spray that sprays hot melt adhesive into a thin thread, a method of attaching a lens-like adhesive by dot printing, as shown in FIG. 2, and a method of using as shown in FIG. A method of providing fine protrusions 6 on the adhesion surface of the lens sheet 2 and applying and bonding an adhesive on the entire surface of the diffusion plate 3, and conversely, providing fine protrusions 6 on the adhesion surface of the diffusion plate 3. The method of apply | coating an adhesive agent to the whole surface of the lens sheet 2 can be illustrated.

  In addition, when providing the protrusion 6 on the bonding surface of the lens sheet 2 or the diffusion plate 3, the shape is not particularly limited as long as an appropriate interval is provided between the lens sheet 2 and the diffusion plate 3 and the bonding portion 4a can be made minute. For example, a cylindrical shape, a prismatic shape, or a hemispherical shape as shown in FIG. 8 can be exemplified, and a prismatic shape (triangular shape) as shown in FIG. 9 or a cross-sectional view as shown in FIG. A rib-shaped projection 6 that is trapezoidal and extends linearly on the lens sheet 2 or the diffusion plate 3 can also be employed.

  In this case, if the peripheral surface of the protrusion 6 is at a deep angle that is nearly perpendicular to the bonding surface, the light incident here is unlikely to be emitted in front of the lens sheet 2, that is, the front luminance is unlikely to increase. Therefore, it is preferable that the peripheral surface of the protrusion 6 be at a shallow angle near the horizontal with respect to the bonding surface. Preferable examples include prism-shaped or coma-shaped protrusions having a large vertex angle, preferably 120 ° or more.

  In the present invention, the specific size of each bonding portion 4a is not particularly limited. In addition, since it is preferable that it is a grade hidden by the diffusion particle 5 contained in the diffusion plate 3, about 0.5 μm to 25 μm, which is the same size as the diffusion particle 5, is considered to be theoretically preferable. There is a limit to the dispersion technology and resin molding technology, and practically it can be used even if it is 10 μm to 100 μm, and the length is limited when it is bonded in a linear shape with a thickness of 100 μm or less. It has been confirmed experimentally.

  In the present invention, the ratio of the total area of the adhesive portion 4a to the total area of the lens sheet composite 1 is not particularly limited, but is preferably 3 to 50%, more preferably 5 to 40%, and particularly preferably 10 to 30%. is there. If the total area is less than 3%, although depending on the type of adhesive, the adhesion between the lens sheet 2 and the diffusion plate 3 is not sufficient, the handling property and assembly workability deteriorate, and the thermal expansion coefficient. If there is a difference between them, the optical performance tends to be uneven due to bending and distortion. Further, if it exceeds 50%, the front luminance tends to be low.

The minute adhesion portion 4a as described above also functions as a diffusing particle and helps to eliminate a slight difference in brightness due to the backlight. Further, when the shape of the adhesive (including the adhesive, the same applies hereinafter) applied to the adhesive surface is formed into a convex lens shape or a spherical shape, the light emitted from the diffusion plate 3 is collected by this adhesive, so the lens sheet The front luminance of the composite 1 is increased.
The method for making the shape of the adhesive convex lens or spherical is not particularly limited. For example, butyl rubber, SBS rubber or the like is used as the adhesive, and this is sprayed with spray glue to make it spherical as shown in FIG. A polypropylene-polyethylene adhesive is used as an agent, and sprayed by curtain spray to form a lenticular lens having a substantially semicircular cross-sectional shape. The adhesive attached by dot printing by adjusting the shape of the printing machine head. There is a method of making the shape into a convex lens shape as shown in FIG.

  Although depending on the type of adhesive used, even if the shape of the adhesive at the time of application is a convex lens shape or a spherical shape, if these are pressed in order to improve the adhesion between the lens sheet 2 and the diffusion plate 3, adhesion will occur. Since the shape of the agent is broken and the final product may not be a convex lens shape or a spherical shape, use a hard or elastic adhesive that does not break the shape by pressing, or do not press the diffusion plate It is preferable to place the lens sheet 2 on the surface 3.

  The material of the lens sheet 2 and the diffusion plate 3 is not particularly limited as long as it is a transparent polymer material, and can be selected from ordinary optical transparent resins. Specific examples thereof include polyolefins such as acrylic resin, polycarbonate, polystyrene, polyvinyl chloride, polypropylene, and polymethylpentene, cyclic polyolefin, polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyamide resins, poly Examples include arylate and polyimide. In addition to the thermoplastic resin, an ultraviolet curable resin can also be used.

The difference in linear expansion coefficient between the diffusion plate 3 and the lens sheet 2 is preferably 5.9 × 10 ⁻⁵ / ° C. or less, more preferably 1.0 × 10 ⁻⁵ / ° C. or less. Within this range, for example, even if there is a temperature change when the power of the liquid crystal display device is turned on / off, the difference in linear expansion is absorbed by the adhesive, so the lens sheet composite in which these are bonded together 1 hardly bends. In particular, if the diffuser plate 3 and the lens sheet 2 are made of the same material and the difference between these linear expansion coefficients is eliminated, no bending or distortion due to temperature change occurs.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

Example 1
Silica particles having an average particle size of 0.5 μm to 2 μm are blended with polycarbonate in an amount of 0.12 g per 100 g of polycarbonate, and this is extruded between a cooling roll having a prism lens pattern engraved on the surface and a rubber roll to sandwich the lens sheet. Created. The thickness of the lens sheet excluding the lens structure was 120 μm, and the lens structure (prism) was an isosceles triangle having a vertical angle of 90 ° and a base of 50 μm. Note that the haze of a flat sheet having a thickness of 120 μm made of the same material was 18%.
With the adhesive surface (surface without the lens pattern) of the lens sheet above, spray glue (Tokyu Hands, trade name: Hands Select Spray glue, butyl rubber adhesive) was sprayed as an adhesive. This was laminated on a diffusion plate made of polycarbonate (PC) (trade name: Panlite Sheet PC9391, Haze: 89.9%, manufactured by Teijin Chemicals Ltd.) to obtain a lens sheet composite of Example 1. The sprayed adhesive had a spherical shape with a diameter of 10 to 30 μm (average of about 20 μm), and the total area of the bonded portion was about 10% of the entire lens sheet composite.
The conceptual diagram of the adhesion surface of the lens sheet sprayed with the spray paste is shown in FIG.

Example 2
A lens sheet composite of Example 2 was obtained in the same manner as Example 1 except that another spray paste (trade name: Davy Bond, SBS rubber adhesive, manufactured by Diabond Co., Ltd.) was used as the adhesive. The sprayed adhesive had a spherical shape with a diameter of 5 to 50 μm (average of about 20 μm), and the total area of the bonded portion was about 3% of the entire lens sheet composite.

Example 3
A lens sheet composite of Example 3 was obtained in the same manner as in Example 1 except that curtain spray (trade name: Morescommelt TN-621, PP-PE adhesive) manufactured by Matsumura Oil Co., Ltd. was used as the adhesive. The sprayed adhesive was in the form of a thread having a width of 50 to 100 μm (average height of about 40 μm), and the total area of the bonded portion was about 35% of the entire lens sheet composite.
FIG. 5 shows a conceptual diagram of the adhesive surface of the lens sheet on which curtain spray is sprayed.

Example 4
The lens sheet composite of Example 4 was used in the same manner as in Example 1 except that a UV curable adhesive (manufactured by Jujo Chemical Co., Ltd., trade name: Reicure-GA) was used as the adhesive and was applied in a convex lens shape by dot printing. The body. The applied adhesive was in the form of dots having a diameter of 80 μm (height of about 3 μm), and the total area of the bonded portions was about 10% of the entire lens sheet composite.
FIG. 6 shows a conceptual diagram of the adhesion surface of the lens sheet to which the UV curable adhesive is applied.

Example 5
The lens sheet composite of Example 5 was obtained in the same manner as in Example 4 except that the number of dots to be printed was increased and the total area of the adhesive portion was about 25% of the entire lens sheet composite.

Example 6
The lens sheet was formed in the same manner as in Example 1 except that the resin was extruded and pinched between a cooling roll with a prism lens pattern engraved on the surface and a cooling roll with a female die with a hemispherical protrusion. Created. This lens sheet has a thickness of 120 μm except for the lens structure of the lens surface and the hemispherical protrusion of the adhesive surface. The hemispherical projection has a circular bottom with a diameter of 50 μm and a height of 25 μm. The arrangement of the protrusions is substantially the same as the arrangement of the dots in Example 4 (see FIG. 6), and is provided every 200 μm in the vertical and horizontal directions.
A double-sided adhesive paste (manufactured by Sekisui Chemical Co., Ltd., trade name: double tack tape, adhesive layer thickness: 5 μm) was used as an adhesive, and this was adhered to the entire upper surface of the diffusion plate. The lens sheet was placed on the lens sheet, and lightly pressed from above the lens sheet to bring the diffuser plate and the lens sheet into close contact with each other, thereby obtaining the lens sheet composite of Example 6.

Example 7
Except that the resin was extruded between a cooling roll with a prism lens pattern engraved on its surface and a cooling roll with a linear projection female mold engraved, the same operation as in Example 6 was carried out. The lens sheet composite of Example 7 was prepared. On the adhesive surface of the lens sheet used in this example, a linear protrusion having a prismatic shape (triangular shape) having a base (frontage) of 50 μm in cross-sectional view and an apex angle of 120 ° is provided in parallel every 200 μm. However, the rest is the same as the lens sheet of Example 6.
FIG. 7 shows a conceptual diagram of the adhesion surface of the lens sheet provided with a triangular linear protrusion.

Examples 8-10
As a straight protrusion, a prismatic shape (Example 8) having a bottom (frontage) of 50 μm in cross-sectional view and a vertex angle of 150 ° (Example 8), a trapezoidal shape having a base (frontage) of 40 μm, a top side of 20 μm, and a height of 10 μm (Example) 9) A lens sheet composite was prepared in the same manner as in Example 7 except that the trapezoidal shape (Example 10) was 20 μm at the bottom (frontage), 10 μm at the top, and 6 μm in height in cross-sectional view.

Examples 11-19
A lens sheet was prepared in the same manner as in Example 1 except that the amount of silica particles blended in the polycarbonate was changed so that the haze became the value shown in Table 1.
On the other hand, silica particles having an average particle size of 0.5 μm to 2 μm were blended with polycarbonate, and a 1 mm thick plate was prepared from this resin, which was used as a diffusion plate. The amount of silica particles was adjusted so that the haze became the value shown in Table 1.
The lens sheet and diffusion plate prepared as described above were bonded together in the same manner as in Example 1 to obtain lens sheet composites of Examples 11-19.

Example 20
1.0 g of crosslinked acrylic particles having an average particle size of 2 μm to 10 μm are blended with polycarbonate per 100 g of polycarbonate, and a cooling roll with prism lens patterns carved on the surface and female molds of convex parts are randomly carved. A lens sheet was prepared by extruding between the cooling rolls and pinching. The thickness of the lens sheet excluding the lens structure and the convex portion on the back surface is 100 μm, and the lens structure (prism) is an isosceles triangle having a top angle of 90 ° and a base of 50 μm and formed on the back surface. The shape of the random convex portion was a circular convex lens shape having a bottom diameter of 90 μm and a height of 20 μm, and the total area of the bottom surface was about 3% of the sheet area. The haze of a flat sheet made of the same material and having a thickness of 100 μm was 43%.
A double-sided adhesive paste (double tack tape described above) having an adhesive layer thickness of 5 μm was used as an adhesive, and this was adhered to the entire upper surface of the same diffusion plate as in Example 1. A lens sheet composite of Example 20 was obtained by placing the above lens sheet thereon and lightly pressing it from above the lens sheet to partially adhere the diffuser plate and the lens sheet. The total area of the bonded portion was about 2.5% of the entire lens sheet composite.

Examples 21-23
Except for the lens structure and the convex part on the back surface, the thickness of the lens sheet was 175 μm (Example 21), 200 μm (Example 22), and 280 μm (Example 23). 23 lens sheet composites were obtained. In addition, the hazes of the flat sheets made of the same material and having thicknesses of 175 μm, 200 μm, and 280 μm were 60%, 64.5%, and 75%, respectively.

Examples 24-26
The lens sheet composites of Examples 24-26 are the same as Example 21 except that the height of the convex portion on the back surface is 21 μm (Example 24), 18 μm (Example 25), and 15 μm (Example 26). did.

Example 27
Example 20 The same as Example 20, except that the amount of crosslinked acrylic particles in the lens sheet material was 0.5 g per 100 g of polycarbonate, and the thickness of the lens sheet excluding the lens part and the convex part on the back surface was 110 μm. 27 lens sheet composites were obtained. In addition, the haze of a flat sheet having a thickness of 110 μm made of the same material was 32%.

Examples 28-30
Except for the lens structure and the convex portion on the back surface, the thickness of the lens sheet was 175 μm (Example 28), 200 μm (Example 29), and 280 μm (Example 30). 30 lens sheet composites were obtained. Note that the hazes of flat sheets made of the same material and having thicknesses of 175 μm, 200 μm, and 280 μm were 41%, 44%, and 53%, respectively.

Example 31
The lens sheet composite of Example 31 in the same manner as in Example 20, except that a double-sided adhesive paste (product name: double tack tape, manufactured by Sekisui Chemical Co., Ltd.) having an adhesive layer thickness of 10 μm was used as the adhesive. It was. The total area of the adhesion part was about 2.8% of the whole lens sheet composite.

Examples 32-34
The shape of the convex portion provided on the back surface is a square having a bottom surface of 100 μm, and the height is 20 μm (Example 32), 18 μm (Example 33), and 15 μm (Example 34). In the same manner as in Example 20, lens sheet composites of Examples 32-34 were obtained. In addition, the total area of the bottom face of the convex part was 3.9% of the sheet area, and the total area of the adhesion part was 3% of the entire lens sheet composite.

Examples 35-37
The lens sheet composites of Examples 35 to 37 were obtained in the same manner as in Examples 32 to 34 except that double-sided adhesive paste having the adhesive layer thickness of 10 μm was used as the adhesive. The total area of the bonded portion was 3.5% of the entire lens sheet composite.

Comparative Example 1
The diffuser plate used in Example 1 was used alone as Comparative Example 1.

Comparative Example 2
A lens sheet laminate in which a lens sheet (product name: GTL-6000, manufactured by Goyo Paper Industries Co., Ltd.) that does not contain diffusing particles on the diffusion plate used in Example 1 is simply stacked without using an adhesive. Obtained as Comparative Example 2.

Comparative Example 3
Comparative Example 3 was obtained by obtaining a lens sheet laminated body which was just superposed in the same manner as Comparative Example 2 except that the same lens sheet used in Example 1 was used as the lens sheet.

Comparative Example 4
Double-sided adhesive paste (made by Sekisui Chemical Co., Ltd., trade name: double tack tape, thickness of adhesive layer) on the entire back side of a lens sheet (product of Goyo Paper Industries Co., Ltd., trade name: GTL-6000) that does not contain diffusing particles : 5 μm) was affixed, placed on the diffusion plate used in Example 1, and lightly pressed from the upper side to be brought into intimate contact, thereby obtaining Comparative Example 4.

Comparative Example 5
Comparative Example 5 was obtained in the same manner as Comparative Example 4 except that the same lens sheet used in Example 1 was used as the lens sheet.

Comparative Example 6
Other than adjusting the amount of the silica particles so that the haze of the diffusion plate becomes the value shown in Table 3, using a lens sheet (trade name: GTL-6000, manufactured by Goyo Paper Industries Co., Ltd.) that does not contain diffusion particles, A lens sheet composite was prepared in the same manner as in Examples 11-19.

Comparative Example 7
A lens sheet composite was prepared in the same manner as in Examples 11 to 19, except that the amount of silica particles was adjusted so that the haze of the lens sheet was the value shown in Table 3, and a diffusion plate containing no diffusion particles was used. did.

About the diffusion sheet (Comparative Example 1), the lens sheet laminate (Comparative Examples 2 and 3), and the lens sheet composite (Comparative Examples 4 to 7) of Examples 1 to 37 and Comparative Examples 1 to 7 Optical characteristics (front brightness, presence / absence of light / dark difference, presence / absence of glare) and handleability were measured by the following methods. The results are shown in Tables 1 to 3.
In addition, the structure of the backlight used for the measurement of an optical characteristic is as follows.
A backlight for a 32-inch television having a length of 400 mm and a width of 705 mm, in which 16 horizontally long cathode-ray tubes were arranged at equal intervals in the vertical direction, was turned on. A reflective plate was disposed below the linear light source in the backlight cavity, and the lens sheet composite of the example or the diffusion plate of the comparative example, the lens sheet laminate, and the lens sheet composite were installed on the upper side. The lens sheet composites of these examples, the lens sheet laminates of the comparative examples, and the lens sheet composites have the lens surface as the emission surface side, and the major axis direction of the prism on the lens surface is made to coincide with the major axis direction of the cathode ray tube. installed.

3. Measurement of front luminance Luminance meter Minolta CA-1500 (manufactured by Konica Minolta Co., Ltd.) measurement area at a distance of 500 mm above the surface on which the lens sheet composite, lens sheet laminate, and diffusion plate (Comparative Example 1) are installed. The luminance at these center points was measured as 8 cm ² .

Glare:
The glare that enters the viewer's eyes directly from each direction due to reflection, refraction, and the like from the light source was visually determined according to the following criteria.
○: Glittering is not visible and the light is exiting gently.
X: Glitter is visible and may be visible after passing through the liquid crystal panel.

Light / dark difference:
The light-dark difference between the linear light source and the gap was visually determined according to the following criteria.
(Double-circle): A light-dark difference is not recognized at all.
○: Almost no difference in brightness is recognized.
Δ: A slight difference in brightness is recognized.
X: A contrast difference is clearly recognized.

Handleability:
The lens sheet composite or the lens sheet laminate was swung 10 times by hand, and whether or not the lens sheet and the diffusion plate were separated was visually determined according to the following criteria.
○: Separation could not be confirmed even after rocking.
X: Separation was confirmed during or after rocking.

Examples 38-43
As resins constituting the diffusion plate, polyethylene (PE) (Example 38), polypropylene (PP) (Example 39), polymethylmethacrylic acid (PMMA) (Example 40), nylon 6 (Example 41), polyethylene A lens sheet composite was prepared in the same manner as in Example 1 except that terephthalate (PET) (Example 42) and polyethylene naphthalate (PEN) (Example 43) were used.

About Example 1 and Examples 38-43, the reliability test after bonding was done. Table 4 shows the lens sheet material, linear expansion coefficient, and test results. From the results of Table 4, it can be seen that when the difference in linear expansion coefficient between the diffuser plate and the lens sheet is 5.9 × 10 ⁻⁵ / ° C. or less, separation due to temperature change hardly occurs, that is, bending and distortion hardly occur.

Reliability test:
In the reliability test, an operation of raising the temperature from −40 ° C. to + 80 ° C. and cooling it to −40 ° C. is repeated 100 times, and whether or not the lens sheet and the diffusion plate are separated is visually determined according to the following criteria. Was done. The determination was performed twice after 10 times and after 100 times.
○: Separation could not be confirmed after the test.
X: Separation was confirmed during or after the test.

  As described above, the lens sheet composite of the present invention is a lens sheet composite in which a diffusion plate and a lens sheet are bonded to each other with minute adhesive portions distributed over the entire surface, and the lens sheet includes diffusion particles. As a result, the optical performance is not inferior to the case where the diffusion plate and the lens sheet are overlapped without using an adhesive, and the handling and assembly workability can be greatly improved. Since the optical performance is not deteriorated because the light source does not break, and the brightness difference between the linear light source and the gap is difficult to see without impairing the front luminance, it is useful as a lens sheet composite for a liquid crystal display device. .

The present invention was made to achieve the above object, and is a lens sheet composite comprising a diffuser plate and a lens sheet bonded together with minute adhesion portions distributed over the entire surface ,
The lens sheet viewed contains diffusing particles,
The ratio (B) / (A) of the haze (B) of the lens sheet to the haze (A) of the diffusion plate is 0.19 to 2.22, and the value of haze (A) × haze (B) is The content of the lens sheet composite is 380 or more . .
However, the haze (A) of the diffuser plate is a value measured according to JIS K7136, and the haze (B) of the lens sheet is a thickness obtained by removing the lens structure from the lens sheet, and the sheet having both sides flat is JIS. It is a value measured by K7136.

Invention relating to claim 2 of the present invention, a lens sheet, the lens sheet composite according to claim 1, f noise (B) is characterized by comprising the material to be 18.0 to 78.0% Content.

The invention according to claim 3 of the present invention is characterized in that the diffusion plate is made of a material having a haze (A) of 11.0 to 95.1%. The content is a complex.

Invention according to claim 4 of the present invention, the shape of the adhesives to the contents of the lens sheet composite according to any one of claims 1 to 3, characterized in that a convex lens or spherical.

Invention relating to aspect 5 of the present invention, any one of claims 1 to 4 difference of the diffusion plate and the lens sheet coefficient of linear expansion is equal to or is 5.9 × 10 ^-5 / ℃ or less The content is the lens sheet composite according to Item 1.

The invention according to claim 6 of the present invention includes the lens sheet composite according to claim 5 , wherein the material of the diffusion plate and the lens sheet is the same.

In the lens sheet composite of the present invention, a diffusion sheet and a lens sheet containing diffusion particles (hereinafter sometimes simply referred to as a lens sheet) are bonded together with minute adhesive portions distributed over the entire surface. Since the lens sheet can be handled integrally, the handling and assembling workability are excellent, and since the lens sheet is fixed to the diffusion plate and does not swing, the lens sheet is formed using a material with low hardness, for example. However, the lens structure is not broken by friction with other optical sheets, and therefore, a lens sheet with high optical performance can be used even if the strength is slightly weak. In addition, since the bonding is partially performed at a fine adhesion portion, and the diffusion particles are included in the lens sheet, the adhesion portion is hidden by the diffusion particles and is hardly noticeable. Even if the thermal expansion coefficient of the diffuser plate and the lens sheet are different, the difference in linear expansion coefficient is absorbed by the partial adhesive part, and the occurrence of bending and distortion is prevented. Optical performance not inferior to the case can be exhibited.
Furthermore, it is possible to provide a high-quality backlight with high brightness of the front surface, in which the difference in brightness between the linear light source and the gap, that is, the location where the linear light source exists is difficult to visually recognize.
Further, the ratio of the haze (B) of the lens sheet to the haze (A) of the diffuser is 1: 1.19 to 2.22, and the value of haze (A) × haze (B) is 380 or more. Combined with the light diffusion effect of the lens sheet, the brightness difference of the backlight is sufficiently eliminated to make it difficult to visually recognize the position of the light source, and the brightness of the entire screen is maintained without blocking unnecessary light. Can do.

When the diffusing particles are blended in the diffusing plate so that the haze is 11.0 to 95.1%, the diffusing plate functions in the same manner as a normal diffusing plate, and the brightness difference of the backlight is reduced .

  The present invention relates to a lens sheet composite comprising a lens sheet disposed on the surface side of a backlight of a liquid crystal display device or the like and a diffusion plate, and in particular, handling and assembly workability are good, and the lens structure of the lens sheet is broken. The present invention relates to a lens sheet composite in which uniform optical performance can be obtained even when the thermal expansion coefficient of the diffuser plate and the lens sheet is different, and further, the difference in brightness between the linear light source and the gap between them is difficult to visually recognize. .

  In recent years, liquid crystal display devices have been used in various fields, and various performances are required depending on the respective applications. OA equipment, personal computers, word processors, etc. have strong demands for weight reduction, thinning, high definition, and power saving, and liquid crystal display devices have a wider field of view, wider screen, and higher brightness. The demand is getting stronger.

In order to meet these requirements, the directivity of light is changed, that is, a film or sheet (hereinafter simply referred to as a lens) having a condensing function in order to change the direction of light in an unnecessary direction and condense it in front of the observer. The use of sheet) is common.
When this lens sheet is attached to the diffusion plate using an adhesive, the difference in refractive index between the diffusion plate and the adhesive layer or between the adhesive layer and the lens sheet is small, so that the diffusion sheet or the like is changed from the diffusion plate to the lens sheet. Since the emitted light is not collected effectively, the front brightness may hardly increase, and if the lens sheet and the diffusion plate have different coefficients of thermal expansion, they will be bent and distorted, resulting in uniform optical performance. Since there was a problem that it could not be obtained, the assembly was completed simply by superimposing without using an adhesive or the like.
However, in this case, the lens sheet, the diffusion plate, and other members must be handled at the same time so that they are not scattered during assembly, that is, handling and assembly workability are poor, and the cost for assembling the device is low. It was the cause of up.

  In addition, the lens sheet may sway during assembly or when the finished product after assembly is transported simply by overlapping, in this case, the lens surface is rubbed with another optical sheet at this time, The lens structure may be broken and the predetermined optical performance may not be exhibited, or the broken lens structure may become powdery and adhere to other optical sheets to hinder the performance. In order to avoid such a situation, PET having a relatively high strength is often used as a material. However, the degree of freedom in designing the lens sheet is impaired by that amount, and in designing a high-performance lens sheet. It was an obstacle.

Furthermore, in recent years, point light sources such as LEDs have also been used, but a linear cathode ray tube is frequently used, and in order to homogenize the light from the linear light source, it passes through a diffusion plate having a light diffusion function. A planar light source is used. If light is diffused and homogenized to such an extent that the location where the light source is present cannot be visually recognized, the amount of transmitted light is impaired and the light utilization efficiency is deteriorated.
Therefore, in order to increase the light use efficiency and prevent the presence of the light source from being visible, a diffusion sheet with an adjusted light diffusivity is used in the upper or lower part of the lens sheet or both above and below (for example, , See Patent Document 1).
However, in this case, the number of parts increases, and handling properties and assembly workability deteriorate.
JP 2007-3908 A (FIGS. 10 and 13)

  The present invention solves the above-mentioned conventional problems, has good handleability and assembling workability, does not break the lens structure, and can obtain uniform optical performance even when the thermal expansion coefficient is different between optical sheets. It is an object of the present invention to obtain a lens sheet composite in which the existence location of is difficult to visually recognize.

The present invention was made to achieve the above object, and is a lens sheet composite comprising a diffuser plate and a lens sheet bonded together with minute adhesion portions distributed over the entire surface,
The lens sheet includes diffusing particles, and the haze (B) is 18.0 to 78.0%.
The diffusion plate has a haze (A) of 11.0 to 95.1%,
The ratio (B) / (A) of the haze (B) of the lens sheet to the haze (A) of the diffusion plate is 0.19 to 2.22, and the value of haze (A) × haze (B) is The lens sheet composite is characterized by being 850 to 7000 .
However, the haze (A) of the diffuser plate is a value measured according to JIS K7136, and the haze (B) of the lens sheet is a thickness obtained by removing the lens structure from the lens sheet, and the sheet having both sides flat is JIS. It is a value measured by K7136.

The invention according to claim 2 of the present invention includes the lens sheet composite according to claim 1, wherein the adhesive has a convex lens shape or a spherical shape.

Invention relating to Claim 3 of the present invention, a lens sheet according to claim 1 or 2 difference of the diffusion plate and the lens sheet coefficient of linear expansion is equal to or is 5.9 × 10 ^-5 / ℃ or less The content is a complex.

The invention according to claim 4 of the present invention includes the lens sheet composite according to claim 3 , wherein the material of the diffusion plate and the lens sheet is the same.

In the lens sheet composite of the present invention, a diffusion sheet and a lens sheet containing diffusion particles (hereinafter sometimes simply referred to as a lens sheet) are bonded together with minute adhesive portions distributed over the entire surface. Since the lens sheet can be handled integrally, the handling and assembling workability are excellent, and since the lens sheet is fixed to the diffusion plate and does not swing, the lens sheet is formed using a material with low hardness, for example. However, the lens structure is not broken by friction with other optical sheets, and therefore, a lens sheet with high optical performance can be used even if the strength is slightly weak. In addition, since the bonding is partially performed at a fine adhesion portion, and the diffusion particles are included in the lens sheet, the adhesion portion is hidden by the diffusion particles and is hardly noticeable. Even if the thermal expansion coefficient of the diffuser plate and the lens sheet are different, the difference in linear expansion coefficient is absorbed by the partial adhesive part, and the occurrence of bending and distortion is prevented. Optical performance not inferior to the case can be exhibited.
Furthermore, it is possible to provide a high-quality backlight with high brightness of the front surface, in which the difference in brightness between the linear light source and the gap, that is, the location where the linear light source exists is difficult to visually recognize.
Further, the haze (B) of the lens sheet is set to 18.0 to 78.0%, the haze of the diffusion plate is set to 11.0 to 95.1%, and the haze (B) of the lens sheet and the haze (A) of the diffusion plate are set. And the ratio of 0.19 to 2.22 and haze (A) × haze (B) of 850 to 7000 , combined with the light diffusion effect of the lens sheet, the backlight It is possible to sufficiently eliminate the brightness difference and make it difficult to visually recognize the position of the light source, and to keep the brightness of the entire screen without blocking unnecessary light.

Since the lens sheet bends the light incident parallel to the normal to a predetermined angle, the haze of the lens sheet cannot be directly measured by the method defined in JIS K7136. The haze is measured for a sheet made of the above material and having a thickness obtained by removing the lens structure from the lens sheet and flat on both sides.

If the difference in linear expansion coefficient between the diffusion plate and the lens sheet is 5.9 × 10 ⁻⁵ / ° C. or less, even if the diffusion plate and the lens sheet expand and contract due to temperature change, the difference in linear expansion coefficient is absorbed by the adhesive part. Therefore, almost no bending or distortion occurs. In particular, since the linear expansion coefficient is the same when the material of the diffusion plate and the lens sheet is the same, no bending or distortion due to a temperature change occurs.

FIG. 1 is a conceptual diagram showing an example of a lens sheet composite of the present invention. FIG. 2 is a conceptual diagram showing another example of the lens sheet composite of the present invention. FIG. 3 is a conceptual diagram showing still another example of the lens sheet composite of the present invention. FIG. 4 is a conceptual diagram of the adhesive surface of the lens sheet used in Example 1. FIG. 5 is a conceptual diagram of the adhesive surface of the lens sheet used in Example 3. FIG. 6 is a conceptual diagram of the adhesive surface of the lens sheet used in Example 4. FIG. 7 is a conceptual diagram of the adhesive surface of the lens sheet used in Example 7. FIG. 8 is a conceptual cross-sectional view showing an example of a protrusion in the present invention. FIG. 9 is a conceptual cross-sectional view showing another example of the protrusion in the present invention. FIG. 10 is a conceptual cross-sectional view showing still another example of the protrusion in the present invention.

DESCRIPTION OF SYMBOLS 1 Lens sheet complex 2 Lens sheet 3 Diffusion plate 4 Adhesive 4a Adhesive part 5 Diffusing particle 6 Protrusion

As shown in FIG. 1, the lens sheet composite 1 of the present invention is formed by bonding the diffusion plate 3 and the lens sheet 2 with the minute adhesive portions 4a of the adhesive 4 distributed over the entire surface. a lens sheet composite 1, the lens sheet 2 is viewed contains diffusing particles 5, and a haze (B) is 18.0 to 78.0%, the diffusion plate has a haze (a) 11.0 The ratio (B) / (A) of the haze (B) of the lens sheet to the haze (A) of the diffusion plate is 0.19 to 2.22, and haze (A). X The value of haze (B) is 850 to 7000 .
However, the haze (A) of the diffuser plate is a value measured according to JIS K7136, and the haze (B) of the lens sheet is a thickness obtained by removing the lens structure from the lens sheet, and the sheet having both sides flat is JIS. It is a value measured by K7136.

The lens sheet 2 used in the present invention has a lens surface provided with a three-dimensional pattern (hereinafter referred to as a lens pattern) having a condensing function on one surface and an adhesive surface on the other surface.
The lens pattern provided on the lens surface is not particularly limited as long as it has a condensing function. For example, usable lens patterns include a large number of triangular prisms having a triangular cross section and adjacent bases, and the top ridges are substantially parallel. Prism arranged in such a way; convex lenticular lens in which a plurality of semi-cylindrical or semi-elliptical cylinders whose cross-sections are semicircular or semi-elliptical and whose bases are adjacent to each other are arranged substantially in parallel; pyramid type quadrangular pyramid Examples thereof include a pattern in which a three-dimensional shape selected from a cubic corner-like triangular pyramid and a hemispherical object is provided on a plane.
Note that a large liquid crystal display device needs to be visible from the left and right sides of the screen, such as when viewing a single screen with a large number of people, but rarely observes the screen from above and below. Therefore, in this type of lens sheet composite 1, it is preferable that the light emitted from the screen is diffused in the left-right direction and condensed in the up-down direction. When a prism lens sheet or a lenticular lens sheet that focuses light only in the direction is used and the lens sheet composite 1 using the lens sheet 2 is installed on the screen, the length direction of the prism or lenticular lens is set with respect to the screen. It is preferable to adjust it horizontally.

  The shape of the adhesive surface is not particularly limited as long as it does not excessively interfere with the light condensing function of the lens surface, but a flat surface without unevenness, an uneven surface with many cylindrical protrusions protruding, and many linear protrusions with a rectangular cross section The provided uneven surface can be exemplified, and a three-dimensional pattern similar to the lens pattern can be provided as long as the condensing function of the lens surface is not canceled.

  The thickness of the lens sheet 2 is not particularly limited, and can be the same thickness as that of a normal lens sheet. Specifically, the thickness is usually about 50 to 500 μm.

In the present invention, the lens sheet 2 includes diffusing particles 5. As the usable diffusing particles 5, all the diffusing particles 5 conventionally used for diffusing plates, diffusing sheets and the like can be used, but it is preferable to select a type having a high total light transmittance and a large haze.
Specifically, examples of the inorganic particles include aluminum silicate, calcium silicate, silica, alumina, calcium carbonate, and the like. Examples of the organic particles include cross-linked polyacrylate and silicon resin.
The average particle diameter of the diffusion particles 5 is preferably 0.5 μm to 25 μm. Even if the average particle size is less than 0.5 μm or more than 25 μm, the diffusion function tends to be lowered.

Diffusing particles 5 has a haze of the lens sheet 2, 1 8.0 to 78.0%, the good Mashiku 20.0 to 60.0%, more preferably to the extent that becomes 30.0 to 40.0% The amount is blended into the transparent resin. If the haze is less than 18.0%, a slight dark portion generated in the bonded portion 4a may be seen, and if it exceeds 78.0%, the front luminance may be lowered and the screen may become dark.
Since the specific amount of the diffusing particles 5 varies depending on the transparency, the particle size, the refractive index, the refractive index of the transparent resin constituting the lens sheet 2, the thickness of the lens sheet 2, and the like. For example, when silica particles having an average particle size of 0.5 μm are used as the diffusing particles 5, the transparent resin constituting the lens sheet 2 is polycarbonate, and the thickness of the lens sheet 2 is 120 μm, the amount is 0.1 to 100 g of the transparent resin. About 5 to 1.5 g is blended.

  Usually, the haze is measured by a method defined in JIS K7136. However, since the lens sheet 2 bends light incident in parallel with the normal to a predetermined angle, the haze can be directly measured by this method. Can not. Therefore, in the present invention, using the same material as the lens sheet 2, a sheet having a thickness obtained by removing the lens structure from the lens sheet 2 and flat on both sides is prepared, and the haze of this sheet is set according to JIS K7136. The value was determined as the haze of the lens sheet 2. Thereby, even if the adhesion part 4a is arrange | positioned in the thinnest part (part corresponded to the bottom part of a lens pattern) of the lens sheet 2, the dark part which generate | occur | produces in the adhesion part 4a can fully be hidden.

  The lens sheet 2 can be prepared by a normal method. That is, the diffusion particles 5 are dispersed in the transparent resin in the same manner as in the case of preparing a normal diffusion sheet obtained by blending the diffusion particles 5 with a transparent resin, and a normal lens sheet is prepared using this resin. A lens sheet used in the present invention by a method similar to the above, for example, a method in which a resin is extruded between a metal roll and a rubber roll on which a lens pattern is engraved, and the lens pattern is transferred between the metal roll and the rubber roll. Can be created.

The diffusion plate 3 used in the present invention has a light incident surface on which light from a backlight is irradiated and an adhesive surface to which the lens sheet 2 is adhered.
The diffusing plate 3 in the present invention may be a translucent translucent plate-like member that does not warp or bend due to its own weight, and examples thereof include an acrylic or polycarbonate plate in which the diffusing particles 5 are dispersed and blended. However, in the present invention, since the lens sheet 2 has a part of the dispersing action, the amount of the diffusing particles 5 can be smaller than that of a normally used diffusing plate, and the total amount of light is increased by that amount. Brightness also increases.

If the haze of the diffusion plate 3 is extremely low and only the lens sheet 2 has a diffusing action for eliminating the difference in brightness due to the backlight being seen through, the translucency of the lens sheet 2 is significantly reduced. On the other hand, the transmissivity of the entire lens sheet composite 1 is lowered and the front luminance tends to be lowered, so that the haze of the diffusion plate 3 is 11.0 to 95.1%, preferably 30.0 to 90. . 0%, particularly preferably blended diffusing particles 5 so that 50.0 to 85.0%, decrease the haze of the correspondingly lens sheet 2 shall be the range described above. When the haze of the diffusing plate 3 exceeds 95.1%, the haze of the diffusing plate is sufficient to eliminate the difference in brightness of the backlight alone, and the lens sheet 2 is sufficient to eliminate the dark portion generated alone in the bonding portion 4a. Since the hazes of the lens sheets overlap, the transmissivity of the entire lens sheet composite 1 tends to decrease, and the front luminance tends to decrease.

The ratio (B) / (A) is 0 haze of the diffusion plate 3 haze of the lens sheet 2 for (A) (B). 19~2.22 , the good Mashiku 0.20 to 0.81, more preferably was adjusted to 0.40 to 0.50, by adjusting so that the value of haze (a) × haze (B) is 8 50 or more, a brightness difference of the backlight in the entire lens sheet composite 1 While being able to eliminate effectively, the dark part which generate | occur | produces in the adhesion part 4a with the lens sheet 2 can be hidden, Furthermore, the transmissivity does not fall so much and front brightness can be raised. The upper limit of the value of haze (A) x haze (B) is preferably about 7000 from the viewpoint of making it difficult to visually recognize the difference in brightness and ensuring light transmittance.

  In the present invention, the lens sheet 2 and the diffusing plate 3 are bonded to each other at a minute bonding portion 4a. The specific bonding method is not particularly limited as long as the area of each bonding portion 4a is small. For example, as shown in FIG. 1, a so-called spray that sprays a fine spherical bonding component with a spray. A method of using glue, a method of using a so-called curtain spray that sprays hot melt adhesive into a thin thread, a method of attaching a lens-like adhesive by dot printing, as shown in FIG. 2, and a method of using as shown in FIG. A method of providing fine protrusions 6 on the adhesion surface of the lens sheet 2 and applying and bonding an adhesive on the entire surface of the diffusion plate 3, and conversely, providing fine protrusions 6 on the adhesion surface of the diffusion plate 3. The method of apply | coating an adhesive agent to the whole surface of the lens sheet 2 can be illustrated.

  In addition, when providing the protrusion 6 on the bonding surface of the lens sheet 2 or the diffusion plate 3, the shape is not particularly limited as long as an appropriate interval is provided between the lens sheet 2 and the diffusion plate 3 and the bonding portion 4a can be made minute. For example, a cylindrical shape, a prismatic shape, or a hemispherical shape as shown in FIG. 8 can be exemplified, and a prismatic shape (triangular shape) as shown in FIG. 9 or a cross-sectional view as shown in FIG. A rib-shaped projection 6 that is trapezoidal and extends linearly on the lens sheet 2 or the diffusion plate 3 can also be employed.

  In this case, if the peripheral surface of the protrusion 6 is at a deep angle that is nearly perpendicular to the bonding surface, the light incident here is unlikely to be emitted in front of the lens sheet 2, that is, the front luminance is unlikely to increase. Therefore, it is preferable that the peripheral surface of the protrusion 6 be at a shallow angle near the horizontal with respect to the bonding surface. Preferable examples include prism-shaped or coma-shaped protrusions having a large vertex angle, preferably 120 ° or more.

  In the present invention, the specific size of each bonding portion 4a is not particularly limited. In addition, since it is preferable that it is a grade hidden by the diffusion particle 5 contained in the diffusion plate 3, about 0.5 μm to 25 μm, which is the same size as the diffusion particle 5, is considered to be theoretically preferable. There is a limit to the dispersion technology and resin molding technology, and practically it can be used even if it is 10 μm to 100 μm, and the length is limited when it is bonded in a linear shape with a thickness of 100 μm or less. It has been confirmed experimentally.

  In the present invention, the ratio of the total area of the adhesive portion 4a to the total area of the lens sheet composite 1 is not particularly limited, but is preferably 3 to 50%, more preferably 5 to 40%, and particularly preferably 10 to 30%. is there. If the total area is less than 3%, although depending on the type of adhesive, the adhesion between the lens sheet 2 and the diffusion plate 3 is not sufficient, the handling property and assembly workability deteriorate, and the thermal expansion coefficient. If there is a difference between them, the optical performance tends to be uneven due to bending and distortion. Further, if it exceeds 50%, the front luminance tends to be low.

The minute adhesion portion 4a as described above also functions as a diffusing particle and helps to eliminate a slight difference in brightness due to the backlight. Further, when the shape of the adhesive (including the adhesive, the same applies hereinafter) applied to the adhesive surface is formed into a convex lens shape or a spherical shape, the light emitted from the diffusion plate 3 is collected by this adhesive, so the lens sheet The front luminance of the composite 1 is increased.
The method for making the shape of the adhesive convex lens or spherical is not particularly limited. For example, butyl rubber, SBS rubber or the like is used as the adhesive, and this is sprayed with spray glue to make it spherical as shown in FIG. A polypropylene-polyethylene adhesive is used as an agent, and sprayed by curtain spray to form a lenticular lens having a substantially semicircular cross-sectional shape. The adhesive attached by dot printing by adjusting the shape of the printing machine head. There is a method of making the shape into a convex lens shape as shown in FIG.

  Although depending on the type of adhesive used, even if the shape of the adhesive at the time of application is a convex lens shape or a spherical shape, if these are pressed in order to improve the adhesion between the lens sheet 2 and the diffusion plate 3, adhesion will occur. Since the shape of the agent may be broken and the final product may not be a convex lens shape or a spherical shape, use a hard or elastic adhesive that does not break the shape by pressing, or do not press the diffusion plate It is preferable to place the lens sheet 2 on the surface 3.

  The material of the lens sheet 2 and the diffusion plate 3 is not particularly limited as long as it is a transparent polymer material, and can be selected from ordinary optical transparent resins. Specific examples thereof include polyolefins such as acrylic resin, polycarbonate, polystyrene, polyvinyl chloride, polypropylene, and polymethylpentene, cyclic polyolefin, polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyamide resins, poly Examples include arylate and polyimide. In addition to the thermoplastic resin, an ultraviolet curable resin can also be used.

The difference in linear expansion coefficient between the diffusion plate 3 and the lens sheet 2 is preferably 5.9 × 10 ⁻⁵ / ° C. or less, more preferably 1.0 × 10 ⁻⁵ / ° C. or less. Within this range, for example, even if there is a temperature change when the power of the liquid crystal display device is turned on / off, the difference in linear expansion is absorbed by the adhesive, so the lens sheet composite in which these are bonded together 1 hardly bends. In particular, if the diffuser plate 3 and the lens sheet 2 are made of the same material and the difference between these linear expansion coefficients is eliminated, no bending or distortion due to temperature change occurs.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

Example 1
Silica particles having an average particle size of 0.5 μm to 2 μm are blended with polycarbonate in an amount of 0.12 g per 100 g of polycarbonate, and this is extruded between a cooling roll having a prism lens pattern engraved on the surface and a rubber roll to sandwich the lens sheet. Created. The thickness of the lens sheet excluding the lens structure was 120 μm, and the lens structure (prism) was an isosceles triangle having a vertical angle of 90 ° and a base of 50 μm. Note that the haze of a flat sheet having a thickness of 120 μm made of the same material was 18%.
With the adhesive surface (surface without the lens pattern) of the lens sheet above, spray glue (Tokyu Hands, trade name: Hands Select Spray glue, butyl rubber adhesive) was sprayed as an adhesive. This was laminated on a diffusion plate made of polycarbonate (PC) (trade name: Panlite Sheet PC9391, Haze: 89.9%, manufactured by Teijin Chemicals Ltd.) to obtain a lens sheet composite of Example 1. The sprayed adhesive had a spherical shape with a diameter of 10 to 30 μm (average of about 20 μm), and the total area of the bonded portion was about 10% of the entire lens sheet composite.
The conceptual diagram of the adhesion surface of the lens sheet sprayed with the spray paste is shown in FIG.

Example 2
A lens sheet composite of Example 2 was obtained in the same manner as Example 1 except that another spray paste (trade name: Davy Bond, SBS rubber adhesive, manufactured by Diabond Co., Ltd.) was used as the adhesive. The sprayed adhesive had a spherical shape with a diameter of 5 to 50 μm (average of about 20 μm), and the total area of the bonded portion was about 3% of the entire lens sheet composite.

Example 3
A lens sheet composite of Example 3 was obtained in the same manner as in Example 1 except that curtain spray (trade name: Morescommelt TN-621, PP-PE adhesive) manufactured by Matsumura Oil Co., Ltd. was used as the adhesive. The sprayed adhesive was in the form of a thread having a width of 50 to 100 μm (average height of about 40 μm), and the total area of the bonded portion was about 35% of the entire lens sheet composite.
FIG. 5 shows a conceptual diagram of the adhesive surface of the lens sheet on which curtain spray is sprayed.

Example 4
The lens sheet composite of Example 4 was used in the same manner as in Example 1 except that a UV curable adhesive (manufactured by Jujo Chemical Co., Ltd., trade name: Reicure-GA) was used as the adhesive and was applied in a convex lens shape by dot printing. The body. The applied adhesive was in the form of dots having a diameter of 80 μm (height of about 3 μm), and the total area of the bonded portions was about 10% of the entire lens sheet composite.
FIG. 6 shows a conceptual diagram of the adhesion surface of the lens sheet to which the UV curable adhesive is applied.

Example 5
The lens sheet composite of Example 5 was obtained in the same manner as in Example 4 except that the number of dots to be printed was increased and the total area of the adhesive portion was about 25% of the entire lens sheet composite.

Example 6
The lens sheet was formed in the same manner as in Example 1 except that the resin was extruded and pinched between a cooling roll with a prism lens pattern engraved on the surface and a cooling roll with a female die with a hemispherical protrusion. Created. This lens sheet has a thickness of 120 μm except for the lens structure of the lens surface and the hemispherical protrusion of the adhesive surface. The hemispherical projection has a circular bottom with a diameter of 50 μm and a height of 25 μm. The arrangement of the protrusions is substantially the same as the arrangement of the dots in Example 4 (see FIG. 6), and is provided every 200 μm in the vertical and horizontal directions.
A double-sided adhesive paste (manufactured by Sekisui Chemical Co., Ltd., trade name: double tack tape, adhesive layer thickness: 5 μm) was used as an adhesive, and this was adhered to the entire upper surface of the diffusion plate. The lens sheet was placed on the lens sheet, and lightly pressed from above the lens sheet to bring the diffuser plate and the lens sheet into close contact with each other, thereby obtaining the lens sheet composite of Example 6.

Example 7
Except that the resin was extruded between a cooling roll with a prism lens pattern engraved on its surface and a cooling roll with a linear projection female mold engraved, the same operation as in Example 6 was carried out. The lens sheet composite of Example 7 was prepared. On the adhesive surface of the lens sheet used in this example, a linear protrusion having a prismatic shape (triangular shape) having a base (frontage) of 50 μm in cross-sectional view and an apex angle of 120 ° is provided in parallel every 200 μm. However, the rest is the same as the lens sheet of Example 6.
FIG. 7 shows a conceptual diagram of the adhesion surface of the lens sheet provided with a triangular linear protrusion.

Examples 8-10
As a straight protrusion, a prismatic shape (Example 8) having a bottom (frontage) of 50 μm in cross-sectional view and a vertex angle of 150 ° (Example 8), a trapezoidal shape having a base (frontage) of 40 μm, a top side of 20 μm, and a height of 10 μm (Example) 9) A lens sheet composite was prepared in the same manner as in Example 7 except that the trapezoidal shape (Example 10) was 20 μm at the bottom (frontage), 10 μm at the top, and 6 μm in height in cross-sectional view.

Example 11-1 7
A lens sheet was prepared in the same manner as in Example 1 except that the amount of silica particles blended in the polycarbonate was changed so that the haze became the value shown in Table 1.
On the other hand, silica particles having an average particle size of 0.5 μm to 2 μm were blended with polycarbonate, and a 1 mm thick plate was prepared from this resin, which was used as a diffusion plate. The amount of silica particles was adjusted so that the haze became the value shown in Table 1.
The lens sheet and diffusion plate prepared as described above were bonded together in the same manner as in Example 1 to obtain the lens sheet composites of Examples 11 to 17 .

Example 18
1.0 g of crosslinked acrylic particles having an average particle size of 2 μm to 10 μm are blended with polycarbonate per 100 g of polycarbonate, and a cooling roll with prism lens patterns carved on the surface and female molds of convex parts are randomly carved. A lens sheet was prepared by extruding between the cooling rolls and pinching. The thickness of the lens sheet excluding the lens structure and the convex portion on the back surface is 100 μm, and the lens structure (prism) is an isosceles triangle having a top angle of 90 ° and a base of 50 μm and formed on the back surface. The shape of the random convex portion was a circular convex lens shape having a bottom diameter of 90 μm and a height of 20 μm, and the total area of the bottom surface was about 3% of the sheet area. The haze of a flat sheet made of the same material and having a thickness of 100 μm was 43%.
A double-sided adhesive paste (double tack tape described above) having an adhesive layer thickness of 5 μm was used as an adhesive, and this was adhered to the entire upper surface of the same diffusion plate as in Example 1. A lens sheet composite of Example 18 was obtained by placing the above lens sheet thereon and lightly pressing it from above the lens sheet to partially adhere the diffuser plate and the lens sheet. The total area of the bonded portion was about 2.5% of the entire lens sheet composite.

Examples 19-21
Lens structure and the back side of the thickness of the lens sheet excluding the convex portion 175 .mu.m (Example 19), 200 [mu] m (Example 20), 280 .mu.m (Example 21) and the other is the same way in Example 19 to Example 18 21 lens sheet composites were obtained. In addition, the hazes of the flat sheets made of the same material and having thicknesses of 175 μm, 200 μm, and 280 μm were 60%, 64.5%, and 75%, respectively.

Examples 22-24
21μm height of the rear surface of the convex portion (Example 22), 18 [mu] m (Example 23), 15 [mu] m and a lens sheet composite (Example 24) and the other in the same manner as in Example 19 Examples 22 to 24 did.

Example 25
Example 18 is the same as Example 18 except that the amount of crosslinked acrylic particles in the lens sheet material is 0.5 g per 100 g of polycarbonate, and the thickness of the lens sheet excluding the lens part and the convex part on the back surface is 110 μm. 25 lens sheet composites were obtained. In addition, the haze of a flat sheet having a thickness of 110 μm made of the same material was 32%.

Examples 26-28
Lens structure and the back side of the thickness of the lens sheet excluding the convex portion 175 .mu.m (Example 26), 200 [mu] m (Example 27), 280 .mu.m (Example 28) and the other Example 25 and Examples 26 to similarly 28 lens sheet composites were obtained. Note that the hazes of flat sheets made of the same material and having thicknesses of 175 μm, 200 μm, and 280 μm were 41%, 44%, and 53%, respectively.

Example 29
The lens sheet composite of Example 29 in the same manner as in Example 18 except that a double-sided adhesive paste (product name: double tack tape manufactured by Sekisui Chemical Co., Ltd.) having an adhesive layer thickness of 10 μm was used as the adhesive. It was. The total area of the adhesion part was about 2.8% of the whole lens sheet composite.

Examples 30-32
The shape of the convex portion provided on the back surface is a square having a bottom surface of 100 μm, and the height is 20 μm (Example 30 ), 18 μm (Example 31 ), and 15 μm (Example 32 ). In the same manner as in Example 18 , the lens sheet composites of Examples 30 to 32 were obtained. In addition, the total area of the bottom face of the convex part was 3.9% of the sheet area, and the total area of the adhesion part was 3% of the entire lens sheet composite.

Examples 33-35
The lens sheet composites of Examples 33 to 35 were obtained in the same manner as in Examples 30 to 32 except that a double-sided adhesive paste (double tack tape described above) having an adhesive layer thickness of 10 μm was used as the adhesive. The total area of the bonded portion was 3.5% of the entire lens sheet composite.

Comparative Example 1
The diffuser plate used in Example 1 was used alone as Comparative Example 1.

Comparative Example 2
A lens sheet laminate in which a lens sheet (product name: GTL-6000, manufactured by Goyo Paper Industries Co., Ltd.) that does not contain diffusing particles on the diffusion plate used in Example 1 is simply stacked without using an adhesive. Obtained as Comparative Example 2.

Comparative Example 3
Comparative Example 3 was obtained by obtaining a lens sheet laminated body which was just superposed in the same manner as Comparative Example 2 except that the same lens sheet used in Example 1 was used as the lens sheet.

Comparative Example 4
Double-sided adhesive paste (made by Sekisui Chemical Co., Ltd., trade name: double tack tape, thickness of adhesive layer) on the entire back side of a lens sheet (product of Goyo Paper Industries Co., Ltd., trade name: GTL-6000) that does not contain diffusing particles : 5 μm) was affixed, placed on the diffusion plate used in Example 1, and lightly pressed from the upper side to be brought into intimate contact, thereby obtaining Comparative Example 4.

Comparative Example 5
Comparative Example 5 was obtained in the same manner as Comparative Example 4 except that the same lens sheet used in Example 1 was used as the lens sheet.

Comparative Example 6
Other than adjusting the amount of the silica particles so that the haze of the diffusion plate becomes the value shown in Table 3, using a lens sheet (trade name: GTL-6000, manufactured by Goyo Paper Industries Co., Ltd.) that does not contain diffusion particles, creating the lens sheet composite in the same manner as in example 11-17.

Comparative Example 7
A lens sheet composite was prepared in the same manner as in Examples 11 to 17 except that the amount of silica particles was adjusted so that the haze of the lens sheet became the value shown in Table 3, and a diffusion plate containing no diffusion particles was used. did.

Comparative Examples 8 and 9
A lens sheet composite was prepared in the same manner as in Comparative Example 7, except that the amount of silica particles was adjusted so that the haze of the diffusion plate was the value shown in Table 3.

About the diffusion sheet (Comparative Example 1), the lens sheet laminate (Comparative Examples 2 and 3), and the lens sheet composite (Comparative Examples 4 to 9 ) of Examples 1 to 35 and Comparative Examples 1 to 9 Optical characteristics (front brightness, presence / absence of light / dark difference, presence / absence of glare) and handleability were measured by the following methods. The results are shown in Tables 1 to 3.
In addition, the structure of the backlight used for the measurement of an optical characteristic is as follows.
A backlight for a 32-inch television having a length of 400 mm and a width of 705 mm, in which 16 horizontally long cathode-ray tubes were arranged at equal intervals in the vertical direction, was turned on. A reflective plate was disposed below the linear light source in the backlight cavity, and the lens sheet composite of the example or the diffusion plate of the comparative example, the lens sheet laminate, and the lens sheet composite were installed on the upper side. The lens sheet composites of these examples, the lens sheet laminates of the comparative examples, and the lens sheet composites have the lens surface as the emission surface side, and the major axis direction of the prism on the lens surface is matched with the major axis direction of the cathode ray tube. installed.

3. Measurement of front luminance Luminance meter Minolta CA-1500 (manufactured by Konica Minolta Co., Ltd.) measurement area at a distance of 500 mm above the surface on which the lens sheet composite, lens sheet laminate, and diffusion plate (Comparative Example 1) are installed. The luminance at these center points was measured as 8 cm ² .

Glare:
The glare that enters the viewer's eyes directly from each direction due to reflection, refraction, etc. from the light source was visually determined according to the following criteria.
○: Glittering is not visible and the light is exiting gently.
X: Glitter is visible and may be visible after passing through the liquid crystal panel.

Light / dark difference:
The light-dark difference between the linear light source and the gap was visually determined according to the following criteria.
(Double-circle): A light-dark difference is not recognized at all.
○: Almost no difference in brightness is recognized.
Δ: A slight difference in brightness is recognized.
X: A contrast difference is clearly recognized.

Handleability:
The lens sheet composite or the lens sheet laminate was swung 10 times by hand, and whether or not the lens sheet and the diffusion plate were separated was visually determined according to the following criteria.
○: Separation could not be confirmed even after rocking.
X: Separation was confirmed during or after rocking.

Examples 36-41
As resins constituting the diffusion plate, polyethylene (PE) (Example 36 ), polypropylene (PP) (Example 37 ), polymethylmethacrylic acid (PMMA) (Example 38 ), nylon 6 (Example 39 ), polyethylene A lens sheet composite was prepared in the same manner as in Example 1 except that terephthalate (PET) (Example 40 ) and polyethylene naphthalate (PEN) (Example 41 ) were used.

For Example 1 and Examples 36-41 were subjected to a reliability test after bonding. Table 4 shows the lens sheet material, linear expansion coefficient, and test results. From the results of Table 4, it can be seen that when the difference in linear expansion coefficient between the diffuser plate and the lens sheet is 5.9 × 10 ⁻⁵ / ° C. or less, separation due to temperature change hardly occurs, that is, bending and distortion hardly occur.

Reliability test:
In the reliability test, an operation of raising the temperature from −40 ° C. to + 80 ° C. and cooling it to −40 ° C. is repeated 100 times, and whether or not the lens sheet and the diffusion plate are separated is visually determined according to the following criteria. Was done. The determination was performed twice after 10 times and after 100 times.
○: Separation could not be confirmed after the test.
X: Separation was confirmed during or after the test.

As described above, the lens sheet composite of the present invention is a lens sheet composite in which a diffusion plate and a lens sheet are bonded to each other with minute adhesive portions distributed over the entire surface, and the lens sheet includes diffusion particles. Furthermore, the haze (A) of the diffuser plate and the haze (B) of the lens sheet are set to a specific range, and the ratio (B) / (A) and the product (A) × (B) of both are specified. With this range , the optical performance is not inferior to the case where the diffusion plate and the lens sheet are overlapped without using an adhesive, and handling and assembly workability can be greatly improved. In addition, since the lens structure is not broken, the optical performance is not deteriorated, and further, it is difficult to visually recognize the difference in brightness between the linear light source and the gap without impairing the front luminance. Therefore, as a lens sheet composite for a liquid crystal display device Useful.

Claims (7)

  A lens sheet composite comprising a diffusion plate and a lens sheet bonded to each other with minute adhesion portions distributed over the entire surface, wherein the lens sheet includes diffusion particles.   The lens sheet is made of a material having a thickness obtained by removing the lens structure from the lens sheet and having a haze measured by JIS K7136 with respect to a flat sheet on both sides, which is 18.0 to 78.0%. Item 12. The lens sheet composite according to Item 1.   The lens sheet composite according to claim 1 or 2, wherein the diffuser plate has a haze of 11.0 to 95.1% measured according to JIS K7136.   The ratio (B) / (A) of the haze (B) of the lens sheet to the haze (A) of the diffusion plate is 0.19 to 2.22, and the value of haze (A) × haze (B) is 380 or more. The lens sheet composite according to claim 3, wherein the lens sheet composite is provided.   The lens sheet composite according to any one of claims 1 to 4, wherein the shape of the adhesive applied to the back surface of the lens sheet is a convex lens shape or a spherical shape. 6. The lens sheet composite according to claim 1, wherein a difference in linear expansion coefficient between the diffusion plate and the lens sheet is 5.9 × 10 ⁻⁵ / ° C. or less.   The lens sheet composite according to claim 6, wherein the material of the diffusion plate and the lens sheet is the same.

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