KR100940762B1 - Light diffusion sheet for rear projection type screen and rear projection type screen using the same - Google Patents

Abstract

The present invention is a light-transmissive substrate; A binder resin layer coated on at least one surface of the substrate by dispersing a binder resin, a curing agent, and a coloring agent in an organic solvent; And a plurality of light transmissive beads fixed to the binder resin layer by applying pressure to the light diffusing sheet for a rear projection screen having a protrusion of the beads exposed from the surface of the binder resin layer, and a rear projection screen using the same. In this regard, when viewed from the front of the viewer side, the light source of the projector is not visible, and the brightness is high and the viewing angle is greatly improved.

Description

Light diffusion sheet for rear projection type screen and rear projection type screen using the same

1 is a diagram illustrating a basic configuration of a projection TV.

2 is a diagram illustrating a structure of a light diffusion sheet of the present invention.

<Brief description of symbols used in the drawings>

11 screen 12 mirror 13 projector

21 Bead 22 Projection of Bead 23 Binder Resin Layer

24: description

The present invention relates to a light diffusing sheet for a rear projection screen and a rear projection screen using the same, and more particularly, to a rear projection screen used for a rear projection display and the like and a rear projection display particularly suitable for a large screen using the same. It relates to a projection screen.

Image projection systems of products such as projection televisions or video projectors, as illustrated in FIG. 1, are image displays such as specially made small cathode ray tubes (CRTs) or liquid crystal displays (LCDs). An image display system in which an image is generated by the projector 13 using a means, and the image is reflected on the mirror 12 to be enlarged and projected on the screen 11, which is a large screen capable of satisfying recent consumer needs. The demand is increasing day by day from the advantage that can be obtained.

Such image projection systems include a front projection type projector called a front type and a rear projection type projector called a rear type according to a method of projecting an image onto a screen as is well known. The light is projected forward along the projection axis towards the screen at which an image is formed on the surface and perceived by the observer in front of the screen.

A conventional rear projection type screen has a diffusion panel on a transparent panel and a spherical lens is adhered thereon by an adhesive resin as shown in Japanese Patent Laid-Open No. 2-77736. In addition, Japanese Patent Laid-Open No. 7-5570 shows a screen sheet material having a bead layer formed of a binder, transparent beads, or colored beads on either side of a substrate made of a material having light transparency. Meanwhile, Korean Patent Publication No. 2001-0042275 discloses an invention having a substrate layer and a light transparent layer having a predetermined thickness on one side of the substrate layer and arranged to partially penetrate the light-transparent beads into the light transparent layer.

The screen according to the related art has a problem in that the light source of the screen is visible due to excessive light transmission, causing the viewer to feel glare. In addition, in order to make the light source visible when the screen is viewed from the viewer side, and to make the light source invisible, a black dye or pigment is mixed and coated with an adhesive or adhesive for fixing the beads, or a separate Fresnel lens should be disposed. At this time, when dye is mixed excessively, it becomes a factor which reduces brightness.

The present invention improves the problems of the prior art as described above, the light source of the projector is not visible when viewed from the front of the viewer side, the light diffusion sheet used in the rear projection type display having high brightness and greatly improved viewing angle, rear projection type using the same Its purpose is to provide a screen and rear projection type system.

In order to achieve the above technical problem, the present invention is a light-transmitting substrate; A binder resin layer coated on at least one surface of the substrate by dispersing a binder resin, a curing agent, and a coloring agent in an organic solvent; And a plurality of light transmissive beads fixed to the binder resin layer by applying pressure, and having a projection of the beads exposed from the surface of the binder resin layer.

In order to achieve the above another technical problem, the present invention provides a rear projection screen using the light diffusion sheet.

In order to achieve the above another technical problem, the present invention provides a rear projection type system using a cathode ray tube or a liquid crystal display as an image generating device in the rear projection type screen.

Hereinafter, the present invention will be described in more detail.

As illustrated in FIG. 2, the light diffusion sheet of the present invention is coated with a binder resin, a curing agent, and a coloring agent dispersed in an organic solvent on a substrate 24 to form a binder resin layer 23, and a plurality of light-permeable beads ( 21) is pressed onto the binder resin layer using a roller to fix the binder resin layer to the binder resin layer, and has a protrusion 22 of the bead having a height t on the surface of the binder resin layer 23. .

The plurality of light-permeable beads 21 include inorganic beads and organic beads, and examples of inorganic beads include silica, zirconia, and glass, and examples of organic beads include acrylic resins, urethane resins, and vinyl chloride resins. . In this case, it is particularly preferable to use glass beads having a refractive index of 1.92 in terms of light transmittance. The particle diameter of the beads 21 is approximately 1 to 200 mu m, preferably 20 to 200 mu m, more preferably 20 to 150 mu m. At this time, when it exceeds the range of the particle diameter of the said beads, a viewing angle worsens, and when it is smaller than the said range, since brightness falls, it is not preferable. The content of the beads is preferably 100 to 1000 parts by weight based on 100 parts by weight of the binder resin. At this time, less than 100 parts by weight is not enough bead evenly applied, if more than 1000 parts by weight is not preferable because the beads are formed in a multi-layer.

In addition, a mixture of beads having various particle diameters rather than beads having a single particle diameter is effective to widen the effect of light diffusion, widen the viewing angle, and make the light source invisible. This is because the number of beads per unit area of the substrate 24 can be increased by filling the voids between the beads having the larger particle diameters with the beads having the smaller particle diameters.

When two kinds of beads having different particle diameters are mixed and used, beads having a large particle diameter (for example, beads having a particle diameter of 50 to 60 µm) and beads having a small particle diameter (for example, particle diameters of 10 to Beads of 50 μm) can be used in a 1: 0.002 to 1: 0.5 mixing weight ratio. In addition, in the case of mixing and using three kinds of beads having different particle diameters, the beads have 1 to 1 beads having a small particle diameter (for example, beads having a particle diameter of 10 to 50 µm) with respect to 100 parts by weight of the total weight of the beads. 50 parts by weight, beads having a medium particle diameter (eg beads having a particle diameter of 50 to 60 μm) 45 to 98 parts by weight, and beads having a large particle diameter (eg beads having a particle diameter of 75 to 106 μm) It is preferable to mix and use to 1 to 50 parts by weight.

In addition, the protrusion 22 of the bead is exposed to the surface instead of being located inside the binder resin layer 23 when pressing the light-transmitting beads 21 on the binder resin layer 23 using a roller. It means a portion of the bead formed. The length from the surface of the binder resin layer to the uppermost end of the protrusion of the bead is called the protrusion height t. In the present invention, the height of the protrusion of the beads, t is preferably 5 to 100 ㎛. At this time, if the height is more than 100 ㎛ sufficient adhesion is not made, if less than 5 ㎛ is not preferable because of insufficient light diffusion. In addition, when the force of the roller is so strongly pressed through the bead-coated binder resin layer and the beads come into direct contact with the substrate, the present inventors cannot achieve the desired product. The pressure range of the roller is preferably 0.05 to 6 kgf.

The binder resin layer 23 of the present invention is formed by dispersing a binder resin, a curing agent, and a coloring agent in single or two or more organic solvents and coating them on at least one side of the substrate. In this case, as the binder resin, a transparent plastic resin, for example, an acrylic resin or a urethane resin may be used in the present invention.

In addition, the colorant serves to improve the contrast of the projected image by absorbing the incident external light and reducing the amount of reflection of the external light, and dyes or pigments are used. In particular, black dyes or pigments are used as the colorant, and carbon black is preferably used as an example. The content of the colorant is 1 to 10 parts by weight, preferably 1.5 to 5.5 parts by weight based on 100 parts by weight of the binder resin. If the content is less than 1 part by weight, the added effect is not expressed, and if the content is greater than 10 parts by weight, the brightness of the light diffusion sheet decreases, which is not preferable.

The curing agent added when the binder resin 23 layer is formed includes an aromatic or aliphatic isocyanate-based curing agent, and the content thereof is 5 to 40 parts by weight based on 100 parts by weight of the binder resin. The binder resin is cured by reacting with a curing agent after the resin layer coating and bead embedding process. At this time, the curing reaction may be made by light or heat.

An example of the organic solvent is MEK (Methylethylketone), the content of which is 10 to 60 parts by weight based on 100 parts by weight of the binder resin.

The method of forming the binder resin layer 23 on the substrate may be adopted without particular limitation as long as it is a method commonly known in the art, and may be, for example, a mayer bar coating method according to the material and shape of the substrate film. Air knife coating method, gravure (gravure) coating method, reverse roll coating method, spray coating method or braid roll coating method can be used arbitrarily selected. At this time, the coating thickness is appropriately 10 to 100 ㎛. If the coating thickness is too thin, it is difficult to fix the beads disposed in the resin layer, and the light source is easy to see, and if the coating thickness is too thick, the luminance is small, which is not preferable.

As the substrate 24 of the present invention, a material having light transparency such as plastic film such as acrylic, polyester, polycarbonate polystyrene, glass, glass fiber, ceramic fiber, fiber cloth, synthetic paper is used, and in particular, the image emitted from the lens of the projector In order to increase the beam transmittance and the brightness of the screen, it may be formed of glass, and may be formed of a transparent acrylic plate in order to be light in weight and inexpensive. Although the thickness of a base material is not specifically limited, 10-1,000 micrometers is preferable in consideration of said transmittance | permeability, brightness | luminance, a weight, etc.

In addition, an acrylic or urethane adhesive may be coated on the opposite side of the substrate 24, or the adhesive tape may be adhered to a desired transparent substrate to be used as a rear projection screen.

The rear projection system employs the projection screen, an image generating device of a high definition cathode ray tube or a liquid crystal display, and a mirror to reflect an image generated from the cathode ray tube or the liquid crystal display to a mirror or to enlarge an image formed on a liquid crystal display panel. It can be configured in such a way that the projection on the screen.

<Example 1>

After dissolving the binder resin, the dye and the curing agent in a solvent with the following composition, it is coated on the surface of the substrate, and a plurality of light-permeable beads are pressed to a pressure of 0.05 to 6 kgf by using a roller on the binder resin layer inside the binder resin layer At the same time, the light diffusion sheet was prepared such that the height of the protrusion of the beads was 40 μm on the surface of the resin layer. The screen was manufactured using this light-diffusion sheet.

<Binder resin layer>

Binder Resin: Acridict AA-960-50, Aekyung Chemical Co., Ltd., 100 parts by weight

Curing agent: Brunnock DN-950, 35 parts by weight of Aekyung Chemical Co., Ltd.

Dye: Carbon Black 3.5 parts by weight

<Bead>

1 bead: glass beads 50 to 60 ㎛ 100 parts by weight

Second Bead: 10 parts by weight of glass beads 10-50 μm

Third bead: glass beads 75 to 106 ㎛ 10 parts by weight

<Example 2>

Example 2 was added to the screen according to the same apparatus and method as described in Example 1, except that 1.5 parts by weight of dye was added based on 100 parts by weight of the binder resin and only the first bead was used as the beads. Prepared.

<Example 3>                     

Example 3 is based on the same apparatus and method as described in Example 1 except that 5.5 parts by weight of dye is added based on 100 parts by weight of the binder resin and only the first bead is used as the beads. Prepared.

<Example 4>

Example 4 manufactured the screen according to the same apparatus and method as described in Example 1, except that 1.5 parts by weight of dye was added based on 100 parts by weight of the binder resin in preparing the resin layer.

Comparative Example 1

Comparative Example 1 is the same apparatus as described in Example 1, except that the beads are pressed onto the binder resin layer at a pressure of 7 to 10 kgf using a roller so that the beads are completely contained in the binder resin layer so that no protrusions are formed. The screen was prepared according to the method.

Comparative Example 2

Comparative Example 2 was the same apparatus as described in Example 3 except that the beads were pressed onto the binder resin layer at a pressure of 7 to 10 kgf using a roller so that the beads were completely contained in the binder resin layer so that no protrusions were formed. The screen was prepared according to the method.

In the screen prepared according to Example 1-4 and Comparative Example 1-2, the brightness and viewing angle were measured according to the following method.

<Measuring luminance and viewing angle>                     

  * Luminometer: BM-7 Luminance Colorimeter (TOPCON)

  1. Prepare a light source of constant intensity under dark conditions

2. Place the specimen in front of the prepared light source

3. Place the luminance meter on the front of the specimen

4. Focus

5. Measurement of Normal Brightness in Specimen

6. Measure the position of the luminance meter by angle

TABLE 1

Presence of light source on screen projection

Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Presence of light radish radish radish radish U U

TABLE 2

Luminance

division Luminance (cd / m ² ) Viewing Angle Luminance (%) normal Normal + 30 degrees (Normal +30 degree luminance) / (normal luminance) Example 1 49.28 26.71 54.27 Example 2 33.98 18.45 54.30 Example 3 29.29 15.18 51.83 Example 4 31.94 21.55 67.55 Comparative Example 1 34.95 13.76 39.37 Comparative Example 2 62.14 15.54 25.01

The results of Tables 1 and 2 show that the light sources are not visible when projecting the screen, as compared with Comparative Examples 1 to 2 in which the height of the protrusion of the beads is 40 µm, compared to Comparative Examples 1 to 2, in which the beads are buried to the substrate. A large value was shown in the viewing angle luminance value.

 The present invention improves the problems of the prior art as described above, the light source of the projector is not visible when viewed from the front of the viewer side, the light diffusion sheet used in the rear projection display and the like with high brightness and greatly improved viewing angle and rear projection type using the same The purpose is to provide a screen.

Although the present invention has been described with reference to one embodiment, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible.

Claims (11)

Light transmissive substrates; A binder resin layer having a thickness of 10 to 100 µm obtained by coating a composition prepared by dispersing a binder resin, a curing agent, and a coloring agent in an organic solvent on at least one side of the substrate; And A plurality of light-permeable beads fixed in the binder resin layer by applying pressure, having a particle diameter of 20 to 200 μm, and having a content of 100 to 1000 parts by weight based on 100 parts by weight of the binder resin; Including, A light diffusing sheet for a rear projection screen having a projecting portion of the bead exposed from the surface of the binder resin layer at a height of 5 to 100 µm. The light diffusion sheet for a rear projection screen according to claim 1, wherein the content of the colorant is 1 to 10 parts by weight based on 100 parts by weight of the binder resin. The light diffusion sheet for a rear projection screen according to claim 1, wherein the colorant is carbon black. delete delete delete The light diffusing sheet for a rear projection screen according to claim 1, wherein the beads consist of two or more kinds of beads having different particle diameters. The light diffusing sheet for a rear projection screen according to claim 1, wherein the beads are inorganic or organic beads. delete A rear projection screen using the light diffusing sheet of any one of claims 1, 2, 3, 7, and 8. A rear projection type system using a cathode ray tube or a liquid crystal display as an image generating device in the rear projection type screen of claim 10.

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